4!»Mii^f-t i);>A. .*i.' .S*i ^fe •'"Vf^M m :h';s,:' ;."■?■ 1- *-"ljte-'^ -a^-i. ■ ^*;v '•«? K^iWfc^ ^<;, :.L-t ■•>;,»*■ iV ac?^^ \ S U P P " ]L E M E N T TO THE THIRD EDITION OF THE EMCYCLOPJEDI^ BRITAMjYICA, OR, A DICTIONARY OF ARTS. SCIENCES, AND MISCELLANEOUS LITERATURE. IN TWO VOLUMES. lUuftrated with Fifty Copperplates. By GEORGE GLEIG, LL.D. F.R.S. Edin. NON IGNORO, QUiE BONA SINT, FIERI MELIORA POSSE DOCTRINA, ET QU*: HON OPTIMA, ALIQUO MODO ACOI TAMEN, ET CORRIGI POSSE. ClCERO. VOL. I. THE SECOND EDITION, WITH IMPROVEMENTS. PRINTED FOR THOMSON BONAR, PARLIAMENT^^QUARE: BY yOHN BtOffN, ANCHOR CLOSE, EDINBURGH. 1803. [CnteteO In StutjonCTU iijsn.] SIB, TO THE KIJVG. AT proceeds frqm no vain confidence in my pwn abilities^ that I presume to solicit for this Work the Protection of a Monarch, who is not more exalted in station^ than he is distinguished^ among the Poten- tates of the Earthy by his 'Taste in Literature^ and his Patronage of Science and the Arts, In conducting to its conclusion the Encyclopedia Britannica, / am conscious only of having been uni- formly influenced by a sincere desire to do fustice to those Principles of Religion, Morality^ and Social Order, of which the Maintenance constitutes the Glory of Your Majesty's Reign, and will, I trust, record Tour Name to the latest Posterity, as the Guardian of the Laws and Liberties of Europe, Iv DEDICATION. T'he French Encyclope'die has been accused^ and justly accujed, of having disseminated^ far and wide^ the seeds of Anarchy and Atheism. If the Encyclo- pjediaBritannica shall, in any degree, counteract the tendency of that pestiferous Work, even these two Vo- lumes will not be wholly unworthy of Tour Majesty's Patronage ; and the Approbation of my Sovereign, added to the consciousness of my own upright intentions ^ will, to me, be an ample reward for the many years of labour which I have employed on them, and on the Volumes to which they are Supplementary . I am, SIR, Your Majesty's Most faithful Subject, And most devoted Servant^ STimiiiG, \ Dee. 10. 1800.J GEORGE GLEIG, SUPPLEMENT TO THE Encyclopaedia Britannica. ^^^^^^^^»^*»»^^n?t^j,-l»* •''■^^^^ I ABE ! Atacifcui A BACISCUS, in architefture, the fame with A- ■ II jfx BACUS; (o'c 'whxch, ki Encyclopttdia. Aberration. ABATIS, or Abattis, is, in military language, ' the name of a kind of retrenchment made of felled trees. When the emergency is fudden, the trees are merely ; laid lengthwife befide each other, with their branches I pointed towards the enemy, to prevent his approach, whilft the trunks ferve as a breaftwork before thofe by whom the abatis is raifed. When the abatis is meant for the defence of a pafs or entrance, the boughs of the trees are generally ftripped of their leaves and pointed; the trunks are planted in the ground; and the boughs are interwoven with each other. It is needlefs to add, that the clofer the trees are laid or planted together, the more fecure is the defence which they afford ; and if, when they are planted, a fmall ditch be dug towards the enemy, and the earth thrown up properly againll the lower part of the aba 's, it will be very difficult to pafs it if well defended. — Simes's Mililary Guide. ABBREVIATION of fractions, in arithmetic and algebra, is the reducing of them to lower terms ; which is done by dividing the numerator and denomi- nator by fome number or quantity which will divide both without leaving a remainder of either. ABERRATION, in optics (in Encycl.), refers the reader to the article Optics, n" 17, 136, 173. It fliould have referred him to Optics, n^ 17, and 251 — ^BFRKATiON of the V'tfual Ray, Is a phenomenon, of which, though fome account of it has been given in the Encyclopaedia (fee Aberration, in aftronomy ; and the article Astronomy, no 337.), one of the moft can- did of our correfpondents requires a fuller explanation. If fuch an explanation be requifite to him, it muft be much more fo to many others; and we know not where to find, or how to devife, one which would be more fa- tisfactory, or more familiar, than the following by Dr Hutton. " This effeft (fay ne) may be explained and fami- liarized by the motion of a line parallel to itfelf, much after the manner that the compoUtion and refolution of forces are explained. If light have a progreffive mo- tion, let the proportion of its velocity to that of the fljteU. earth in her orbit be as the line BC to the line AC; "g- '• then, by the compofition of thefe two motions, the par- ticle of light will feem to deferibe the line B A or DC, *^ SuppL. Voi,. I. Part I. Ahfcif^. A B S inftead of its real courfe BC ; and will appear in the Aterratian direftion AB or CD, iflftead of its true direftion CB. So that if AB reprefent a tube, carried with a parallel motion by an obferve r along the line AC, in the time that a particle of light would move over the fpace BC, the different places of the tube being AB, ab, cd, CD; and when the eye, or end of the tube, is at A, let a particle of light enter the other end at B ; then when the tube is at ab, the particle of light will be at e ex- aftly in the axis of the tube ; and when the tube Is at cd, the particle of light will arrive at/, ftill In the axis of the tube; and, laftly, when the tube arrives at CD, the particle of light will arrive at the eye or point C, and confequently will appear to come in the dlreiftlon DC of the tube, inftea ' the true direftlon BC : and fo on, one particle fuc -.ding another, and formliig a continued ftream or ray of light in the apparent direc- tion DC. So that the apparent angle made by the ray of light with the line AE Is the angle DCE, inftead of the true angle BCE ; and the difference BCD, or ABC, Is the quantity of the aberration." Abehration of the Planets, Is equal to their geocen- tric motion, or, in other words, to the fpace which each appears to move as feen from the earth, during the time that light employs In paffing from the planet to the eye of tlif obferver. Thus the fun's aberration in longitude Is conftantly 20", that being the fpace aftu- ally moved by the earth, but apparently by the fun in 8 minutes and 7 feconds, the time In which light paffes from the fun to the earth. If then the diftance of any planet from the earth be known, the time which light employs in paffing from the planet to the earth mud likewife be known ; for as the dlllance of the fun is to the diftance of the planet, fo is 8 minutes and 7 feconds to that time; and the planet's geocentric motion in that time Is Its aberration, whether It be in longitude, lati- tude, right afcenfion, or declination. See Astrono- my in this Supp'ement. ABOAB, ceffes levied. In India, under different de- nominations, beyond the ilandard rent. ABSCISS, Adscisse, or Abfdjfa, is a part cutoff from a ftraight line, and terminated at fome certain point by an ordinate to a curve ; as AP (tig. 2.), or BP (fig- 3-) The abfclfs may commence either at the vertex of the curve, or at any other fixed point ; and it may be taken either upon the axis or upon the dia- A meter Plate 14^ A B S [ 2 1 ACT Abforptinn, meter of tlie curve, or upon any oilier line diawn in a Abfurdmn giyg,, pofition. Hence there are on the fame given line ' or tliametcv an infinite number of variable abfcifies, ter- minated all at one end by the fame fixed point. In the common parabola (fig. 4.), each ordinate PQ^has bnt one abfcifs AP. In the ellipfe or circle (fig. 2.), the ordinate has two abfciiTes lying on the oppofite fides of it. In general, to each ordinate a line of the fecond kind, or a curve of the firll kind, may have two abfciffes; a line of the third order, three; a line of the fourth order, four; and fo on. ABSORPTION, in Anatomy and Physiology, has been tnirici'^jiuly explained nnder thefe articles in the lincyclopadla ; bnt there is another abforbing power poffefled by different fubllances, which is worthy of at- tention, becaufc it is only by our knowledge of it that we can adapt our clothing to the various climates of the earth. The power to which we allude is that of diffe- rent fubllances ; fuch as wool, cotton, filk, and linen, to abforb or attraft moifture from the atmofphere. On this fubjeft the reader will find fome very inllruftive ex- periments detailed (in Encycl. ), where perhaps he may not have looked for them, under the title Flanel. ABSURDUM, a term made ufe of by mathemati- cians when they dtmoiiftrate any truth, by fliowing that its contrary is impofllble, or involves an abfurdity. Thus Euclid dcmonllrates the truth of the fourth pro- pofition of the firft book of his Elements, by fhowing that its contrary implies this obvious abfurdity — " that two llraight lines may inclofe a fpace." This mode of demonftration is called rsduB'w ad at- fttrdum, and is every whit as conclufive as the direft method; becaufe the contrary of every falfehood muft be truth, and of every truth, falfehood. The young geometrician, however, does not, we be- lieve, feel himfclf fo perfeiSly fatisfied with a demon- llration of this kind, as with thofe which, proceeding from a few felfevident truths, conduits him direftly, by necefiary confequences, to the truth of the propofi- tion to be proved. The reafon is, that he has not yet learned to dillinguilh accurately between the words falfe zr\A Impofflili , different 2tw\ contrary, 'hldiny diffe- rent affertions may be made relating to the fame thing, and -yet be all true or all falfe ; but it is impoffible to make two afiertions diieiSlly contrary to each other, of which' the one fhall not be true and the other falfe. Thus, " fnow is white," " fnow is cold," are different affertions relating to the fame thing, and both true; as, •' fnow is black," " fnow is red," are both falfe : but let it be remembered, that of the firll and fecond, and of the third and fourth of thefe affertions, neither is di- rettly contrary to the other ; nor is any one of them, abftraftly confidered, ImpoJJlble, or fueh as a blind man, who had never felt nor heard of fnow, might not believe upon ordinary teilimony. But were all the men in Europe to tell a native of the interior parts of Africa that fnow is a thing at once nx'hite and not white, cold and not cold, the woolly-headed favage would know as well as the moll fagacious philofopher, that of thefe contrary affertions the one mujl be true and the other muft he falfe. Jull fu it is with relpeft to Euclid's fourth propofition. Had he proved its truth by (howing that its contrary involves this piopofition, that " the diagonal of a fquare is commenfurate with its fide," the fliilful geometrician would indeed have admitted the demonilration, becaufe Adion. he knows well that the diagonal of a fquare is not com- Accelerate menfurate with its fide ; but the tyro in geometry would have been no wifer than before. He knew from the beginning, that the propofition and its contrary cannot both be true ; but which of them is true, and whicli falfe, fuch a demonftration could not have taught him, becaufe he is ignorant of the incommenfurahility cf the diagonal and fide of a fquare. No man, how- ever, is ignorant, tliat two llraight lines cannot inclofe a fpace ; and fince Euclid (hows that the contrary of his propofition implies this abfurdity, no man of com- mon fenfe can entertain a doubt but that the propofi- tion itfelf mull be true. ACCELERATED motios.1 See(Encycl.) Ac- ACCELERATING force, j cELERAnoN; and Mechanics, Seit. VI. — and (this Supplement) Dy- namics. ACTION is a term which has been fufficiently ex- plained in the Encyclopaedia; but fince that article was written, queftions have been agitated refpeftiiig agents, agency, and aBion, which, as tliey have employed fome of t^ie moll eminent philofopher^ of the age, and are connedled with the deareft interefts of man, are cer- tainly entitled to notice in this place. It is the opinion of Dr Reid, and we have adopted it (fee Metaphysics, n° 109, &c. Encycl.), that no being can be an agent, or perform an aSion, in the pro- per fenfe of the v.'ord, which does not poffefs, in fome degree, the powers of will and underftanding. If this opinion be jull, it is obvious, that what are called the powers of nature, iuch as impulfe, attraSion, rcJ>ii//ion, elajlicity, &c. are not, ftridlly fpeaking, ^t/wfrj or caufes, but the effedls of the agency of fome aftive and intel- ligent being ; and that phyjical caufcs, to make ufe of common language, are nothing more than laius or rules, according to which thc^fffn/ produces the effcft. This doflrine has been controverted by a writer whofe acutenefs is equalled only by his virtues ; and. we fliall confider fome of his objeflions to it in another place (fee Cause) : but a queftion of a different kind tails under our prefent confideration ; and perhaps the anfwer which we muil give to it, may go far to remove the objeftions to which we allude. Can an agent operate where, either by itfelf or by an inftrument, it is not prefent ? We think not ; be- caufe agency, or the exertion of power, muft be the agency of fomething. The conftitution of the human mind compels us to attribute every adtion to fome be- ing; but if a being could aft in one place from which it is abfent, it might do the hune in a fecond, in a third, and in all places; and thus we (hould have aftion with- out an agent : for to be abfent from all places is a phrafe of the fame import as not to exift But if a living and intelligent being cannot adl but where it is either im- mediately or inllrumentally prefent, much lefs furely can we attribute events of any kind to the agency of an ab- fent and inanimated body. Yet it has been faid, that " we have every reafon, which the nature of the lui;|e£l and of our own faculties can admit of, to believe, that there are among things inanimate fuch relations, that they may be mutually caufes or principles of change to one another, without any exertion oi poiver, or any o- peration of an agent, ftriftly fo called. Such relations, for aught that we know, may take place among bodies at great diftances from one another, as well as among bodies ACT [ 3 ] A E R bodies really or ft'cmiiigly in aftual coiit,nv,1 ; and they ' may vary both in degree and in kind, according to t!ic diilances between the bodies." That any thiiij ihonld be a caufe or principle of change to another, vvitiiout the exertion of/)owf/-or tlie operation of an aoent, appears to us a palpable contra- diclion ; and we could as eafily conceive any two fides of a trianc'c to be not fjreater than the third (iJe, as re- concile fuch a pvopolition lc> tliat faculty of our minds by which we diiUnirniih truth from falfehood. When we fee one body the apparent caufe of change in ano- ther body, we cannot poiTibly entertain a doubt of the exerilon of poiacr; but whether that power be in the body apparently producing the change, or in a diftinft agent, is a qucllion to which an anfwer will not fo readily be found. Tliat it is in a diftiuft agent, we are ftrongly inclined to believe, not only by the received doftrine concerning the Inertiaof matter, which, though it has been frequently controverted, we have never feen difproved, but much more by cont'idering the import of an obfervation frequently introduced to prove the diredl contrary of our belief. " We cannot be charged (fays the writer whom we have jull quoted) with maintaining the abfurdity, that there may be an effedl without a caufe, when we refer the fall of a ftone to the ground, and the ebbing and flowing of the fea, to the injiuence of the earth on the rtone, and of the fun and moon on the ocean, according to the principle of general gravitation." We admit the truth of this obfervation, provided the influence of the fun and moon on tiie ocean be poffible; but, to us at leaft, it appears impoffible, and is certain- ly inconceiveable. The influence of the fun and moon can here mean nothing but the aS'mn or operation of the fun and moon; but if thefe two bodies be inanimate, they cannot a£l at all, in the proper fenfe of the word ; and whatever they be, it is obvious that they cannot acl immitUalcly on an objetl at fuch a diitance from them as the earth and the ocean. L' they be the agents, they muft operate by an inllrument, as we do when moving obiefts to which our hands cannot reach ; but as it has been fliewn elfewhere (lee Metaphysics, n° 199. and Optics, n" 6?. Encycl.), that neither air nor a;ther, nor any other material inllrument which has yet been thought of, is fufficient to account for the phenomena of attraftion and repulfion, it is furely much more ra- tional to conclude, that the ebbing and flowing of the fea are produced, not by the influence of the, fun and moon, but by the power of fome dillindl agent or agents. What thofe agents are, we pretend not to fay. If the Supreme Being himfelf be the immediate author of every change which takes place in the corporeal world, it is obvious that he acls by fi.Ked rules, of which many are apparent to the moft heedlefs obferver, whilft the difcovery of others is referved for the reward oftheju- dicious application of the faculties which he has given us. If he employs inferior agents to carry on the great operations of nature, it is fnrely not difficult to con- ceive that the powers of thofe agents which were de- rived from him, may by him be rellrained within cer- tain limits, and their exercife regulated by determined laws, in fuch a manner as to make them produce the greatell benefit to the whole creation. Nor let it be thought an objeftion to this theory, that the changes which take place among bodies at great diftanccs from Adli.-.n each other, vary botii in degree and in kind accordino- II to the diilances; tor this variation, which weackiiow- i' ^"''"^y', ledge to be a taft, appears to us wholly unaccountable upon any other hypothefis than that which attributes the difTtrent changes to agents diflinft from the bodies themfelves. Did we perceive all the particles of mat- ter, at all difiances, tending towards each other by u fixed law, we might be led to confider mutual attrac- tion as an eJfent'nU property of that fubllance, and think no more ot inquiring into its caufe, than we think of inquiring into the caufe of cxtenfion. But when we find that the fame particles, which at one dillance fccm to attrac^l each other, are at a different dillance kept afuiider by a power of repulfion, which no force, with which we are acquainted, is able to overcome, we can- not attribute the principle or ctuife of thefe changes to brute matter, but mull refer it to fome other agent exerting power according to a fixed law. It is '-lie fafiiion at prefcnt to defpife all metaphyfi- cal inquiries as abftrufe and nfelefs: and on this account we doiibt not but fome of our readers will turn away from this difquifition with afFedled difguft, vvhilll the petulant and unthinking chemift, proud of poflefling the feerets of his fcience, will deem it fuperfluous to inquire after any other natural agents than thofe of which he has been accullomed to talk. But with the utmolt re- fpeft for the difcoveries made by modern chemifts, which we acknowledge to be both numerous and im- portant, we beg leave to obferve, that though thefe gentlemen have brought to light many events and ope- rations of nature formerly unknown, and have fiiown that thofe operations are carried on by efl;abli(hed laws, none of them can fay with certainty that he has difco- vered a fingle agent. The moft enlightened of them indeed pretend not to have difcovered in one depart- \ ment of fcience more than Newton difcovered in ano- ther ; for they well know that agents and agency can- not be fubjeifted to any kind of phyfical experiments. Our very notions of thefe things are derived wholly from our own confcioufiiefs and re'fleftion ; and when it is confidercd what dreadful confequcnces have in an- other country refulted from that pretended philcfophy which excludes the agency of mind from the univerfe, it is furely time to iriquire whether our confcioufnefs and refleftion do not lead us to refer re.il agency to mind alone. Let this be our apology both to the real and to the afi"ei£led enemies of metaphyfics for endea- vouring to draw their attention to the prefent queftion. It is a queftion of the utmoft importance, as well to fcience as to religion : and if the laws of human thought decide it, as we have endeavoured to (how that they do, -we may without liefitation affirm, that the impious phi- lofophy of France can never gain ground but among men incapable of patient thinking. ADAMAS, a name given, in aftrology, to the moon. jEOLUS, in mechanics, a fmall machine invented by Mr Tidd for refrefliing or changing the air in rooms when it becomes too hot or otherwife unfit for refpira- tion. The aeolus is fo contrived as to fupply the place of a fquare of glafs in the window, where it works, with very little noife, like the fails of a wind-mill or a fmoke-jack. AEROLOGY is a branch of fcience which was de- A 2 detailed A F G [4 Afghans tailed in the Encyclopedia at fiifScient length, and ac- '~'^'™"" cordinjr to the prlnciplis which were then generally ad- mitted by cheitiilh. .Subl'equent experiments, however, liave flioivn, that iome ot thole principles are erroneous, and of coiirie tiiat Iome of the opinions advanced in the article Aerology are inconfiftent with fafts. Thefe opinions mud be corrected ; but inllead of fwelling this volume with a new article Aerology, we apprehend that it will be more acceptable to our fcientific readers to refer them for thofc corredlions to the article Chr- MISTRV in this Supplement. AFGHANS, are a people in India who inhabit a province of Cabu u or Cabulistan (fee Encycl.), and have always been conncfteJ with the kingdoms ot Per- fia and HJndoftan. They boaft of being defcended of Saul the firlt king of Ifrael ; of whofe advancement to the royal dijjnity they give an account which deviates not very widely from the truth. Tliey fay indeed, that their great anccftor was raifed from the rank of a fhep- htrd, not for any princely qualities which he poffeffed, but becaufe his llature was cxadlly equal to the length of a rod which the angel Gabriel had given to the pro- phet Samuel as the nieafure of the ftature of him whom God had deftined to fill the throne of Ifrael. Saul, whofe dtlcent, according to fome of them, was of Judah, and according to olheisof Benjamin, had, they fay, two fons, BtRKiAand Irmia, who fer- ■ved David, and was belovjd by hlmi. The fons of Berkia and Irmia were Afghan and Usbec, who, Curing the reigns of David and Solomon, diftinguifhed thimfelves, the one for his corporeal ftrength, and the ether fur liis learning. So great indeed was the ftrength of Afghan, that we are told it flruck terror even into demons and genii. This hero ufed frequently to make excurfions to the mountains, where his progeny, after his death, eflablifh- ed themfelves, lived in a ftate of independence, built forts, and exterminated infidels. When the fele£t of creatures (the appellation which this people give to Mahomet) appeared upon earth, his fame reached the Jlfghans, who fought him in multitudes under their leaders Kbalid and Aldul Refpid, fons of JValid ; and the prophet honouring them with this reception — " Come, O Muluc, or Kings !" they affumed the title of Melic, whii h they retain to this day. The hiftory, from which this abftraft is taken, gives a long and unintertfting detail of the exploits of the Afghans, and of their zeal in overthrowing the temples of idols. It boafts of the following monarchs of their T3ce who have fat upon the throne of Debli : Sultan ' JiEHLOLE, Afghan LoDi, Suhan S'-candfr, Sultan Irbabim, Shir Shah, Ielaf^ Shah, Adil Shah SuR.. It alfo numbers the following kings of Gaur defccndedof the Afghan chiefs : SoLAIM/^N Shah Gur- zanif Beyazid Shak, and Kutb Shah ; befides whom, their nation, we are told, has produced many conquerors of provinces. The Afghans are fometimes called Solai- mani, either becaufe they were formerly the fubjefts of Solomon king of Ifrael, or becaufe they inhabit the mountains of Solomon. They are llkewife called Pa TANS, a name derived from the BinJi verb Pailna " to ruih," which was given to them by one of the Sultans whom they ferved, in confequence of the alacrity with which they had attacked and conquered his enemies. The province which, they occupy at prefent was for. ] A F G I merly called Roh ; and hence is derived the name of the Afghani Rohdias. The city which was eflablifhed in it by the *""" Afghans was called by them Pufhiver or Pa'fher, and is now the name of the v\ hole diltritt. The feds of the Afghans are very numerous ; of which the principal are, Liodi, Lnhouni, Sur, Sertvatii, Tufufxihi, Bang'i/b, Di/axaui, Kheit'i, Yafin, Kail, and Belnjt. They are MuJ'ulmans, partly ot the Sunni, and partly of the Shiii perfuafion. Though they are great boafters, as we have feen, of the antiquity of their origin, and the reputation of their race, other Mufidmans rcjeft their claim, and confider them as of modern, and even of bafe, extraftion. This is probably a calumny ; for it feems inconfiftent ■with their attention to the purity of their dcfcent — an attention which would hardly be paid by a people not convinced of their own antiquity. They are divided into four chifles. The firft is \.he pure cLifs, confifting of thofe whofe fathers and mothers were Afghans. The ftcond clafs confifts of thofe whofe fathers were Afghans and mothers of another nation. The third clafs contains thofe whofe mothers v/ere Afghans and fathers of ano- ther nation. The fourth clafs is compofed of the chil- dren of women whofe mothers were Afghans and fathers and hufbands of a different nation. Perfons who do not belong to one of thelc clafTes are not called Afghans. This people have at all times dllb"ngul/hed themfclvei by their courage, both fmgly and unitedly, as princi- pals and auxiliaries. They have conquered for their own princes and for foreigners, and have always beea confidered as the main ftrength of the army in which they ferved. As they have been applauded tor virtues, they have alfo been reproached for vices, having fome- times been guilty of treachery, and of adtiiig the bafe part even ot afftiffius. Such is the account of the Afghans publiflicd in the fecond volume of the A fiatic Kefearches. It was tranf- lated from a Pcrlian abridgment of a book written in the Pulhto language, and called The Secrets of the Af~ ghans, and communicated by Henry Vanfittart, Efq; to Sir William Jones, then prefident of the Aliatic So- ciety. Their claim to a defcent from Saul king of li- rael, whom they call Melic Talut, is probably of not a very ancient date ; for the introduftion of the angel Gabriel with his rod, gives to the whole ftory the air of one of thofe many fictions which Mahomet borrowed from the later rabbins. Sir William Jones, however, though he furely gave no credit to this fable, feems to have had no doubt but the Afghans are defcendants of Ifrael. " We learn (fays he) from Esdras, that the ten tribes, after a wandering journey, came to a coun- try called Arfarelh, where we may fuppofe they fet- tled : now the Afghans are faid by the beft Perfian hif- torians to be defcended from the Jems. They hava traditions among themfelves of fuch a defcent ; and it is even afferted, that their families are diftinguifhed by the names of Jeiuj/b tribes, although fince their con- verfion to JJlam, they ftudioufly conceal their origin from all whom they admit not to then fecrets. Tha Pufhio language, of which I have feen a didionary, has a manifell refemblance to the Chaldakk; and a confi- derable dillrift under their dominion is called Ha-i,areth or Haaaret, which might cafdy have been changed into the word ufed by Esdras. 1 ftrongly recommend an inquiry into the literature and hiftory of the Afghans." It Llbategnl II A L M [ It is to co-operate with this accomplidied fcholar tliat we have iiilertcd into our Worli this fhort account ■(jf that fingular people ; and it is with pleafure that, upon the authority of Mr Vimfittart, we can add, that a very particular account of the Afghans has been writ- ten by the late Hafiz Rahmat Khan, a chief of the Rohillahs, from which fuch of our readers as are orien- tal fcliolars may derive much curious information. ALBATEGNI, an Arabic prince of Batan in Me- fopotamia, was a celebrated aflronomer, about the year ofChrilf S8o, as appears by his obfctvations. He is alio called Miihumnui! ben Geier yllbalam, Mahomet the Jon of Geber, and Muhamedes Arailttifis. He made af- tronomical obfervations at Antioch, and at Racah or Arafta, a town of Chaldea, which fonie authors call a town of Syria or of Mefopotamia. He is highly fpo- ken of by Dr Halley, as ilr aJmirandi acumiiiis, ac in admin'tflrand'u olfervnlionilus cxeratai'ijfimus. Finding that the tables of Ptolemy were imperfedt, he computed new ones, which were long ufed as the beft among the Arabs : thefe were adapted to the me- ridian of Aradla or Racah. Albategni compofed in Arabic a work under the title of The Science of the Stars, comprifing all parts of aftronomy, according to Lis own oblervations and thofe of Plolemy. This work, tranflated into I^atin by Plato of Tibur, was publifhtd at Nuremberg in 1537, with fome additions and de- monllrations of Regiomontanus ; and the fame was re- printed at Bologna in 1645, with this author's notes. Dr Halley delefted many faults in thefe editions. — Phi/. Tranf. for 1693, N''204. In this work Albategni gives the motion of the fun's apogee fince Ptolemy's time, as well as the motion of the ftars, which he makes one degree in 70 years. Pie made the hingitude of the full ftar of Aries to be j8° 2' ; and the obliquity of the ecliptic 23° 35'. hnA up- on Albatcgni's obfervations were founded the Aiphon- fine tables ot the moon's motions ; as is obfervcd by Nic. Muler, in the Tab. Frijicie, p. 248. ALDERAIMIN, a ftar of the third magnitude, in the right flioulder of the conftcllation Cepheus. ALFRAGAN, Alfergani, or Fnrgani, a cele- lirated Arabic aflronomer,who flourifned about the year 800. He was fo called from the place of his nativity, Fergan, in Sogdiana, now called Maracanda, or Samar- cand, anciently a part of Badf ria. He is alfo called Ahmed (or Muhciiuncd) lenCothair, or Kalir, He wrote the Elements of Aftronomy in %o chapters or feftions. In this work the author chiefly follows Pto- kmy, ufing the fame hypolhefrs, and the fame terms, and frequently tiling him. Of Alfragan's work there are three Latin tranflations, of which the laft and beft was made by GoHue, proftfTor of mathematics and oriental languages in the univerfity of Leyden. This tranfiation, which was publifhed in 1669, after the death of Golius, is accompanied with liic Arabic text, and with many learned notes on the firft nine chapters, which wonld undoubtedly have been carried to the end, had the tranflator lived to complete his plan. ALGORAB, a fixed ftar of the third magnitude, in the right wing of the conftcllation Corvus. ALHAZEN, an Arabian aftronomer, who flourifti- ed in Spain about the begiiming of the 12th century. See .''1 STKONOM Y, n*'-' 6. Encycl. ALMAMONi was a philofopher and aflronomer, 5 ] A L O who, in the beginning of the 9th century, afcended the Alnramon, throne of the caliphs of Bagdat. He was the fon of -Alnc- Harun Al-Ra(hid, and grandfon of Almaiifor. His *■ name is otherwife written Mamon, Almaon, Umamun, Alamoun, or Al-Maimon. Having been educated with great care, and with a love for the liberal fciences, he applied himfelf to cultivate and encourage them in his own country. For this purpofe he rcquefted the Greek emperors to fupply him with fuch books on phllofophy as they had among them ; and he coUefted fltilful inter- preters to tranflate them into trhe Arabic language. He alfo encouraged his fubjefts to ftudy thein ; fre- quenting the meetings of the learned, and afilfting at their exercifes and deliberations. He caufed Ptolemy's Almagcft to be tranflated in 827, by Ifaac Ben-honain, and Thabet Ben-korah, according to Herbtlot, hut, ac- cording to others, by Scrgiuf, and Alhazen the fon of Jofeph. In his reign, and doubtlefs by his encourage- ment, an aftronomer of Bagdat, named Habafti, com- pofed three fets of aftronomical tables. Alniamon himfelf made many aftronomical obferva- tions, and determined the obliquity of the ecliptic to be then 23° 35' (or 23^33' in fome manufcripts), but Voflius fays 23° 5 1' or 23° 34'. He alfo caufed fl fctble a fiip- ' port, that Ifould tluow down the- largcll with a fingle kick of my foot. The h.orjes on the wctl make their »|uivcrs ot" tlio trunk of this tree when young, whence is derived the name given it by the planters." It becomes not us, fitting in our chambrr, to contro- vert a faft in natural hlllory, of the reality of which we never had an opportunity of judging ; nor would il be proper, on account of our own fecpticifm, to luppreis the narrative of a traveller, who correfts the narratives of former travellers in terms which nothing (hould have diftatcd but the confcioufncfs of his own invariable ve- racity. Yet we hope to be pardoned for exprefling our furprife that, in any part cf the world, trees fliould be found in great numbers 25 or 30 feet high, and (hoot- ing out many branches, which have yet fo loofe a hold of tlie ground, that the largtil of them may be thrown down by the fingle kick of a man's foot.' The reader's furprife will probably equal our's, when he is informed that the author faw one of thefe trees of which the trunk was ten feet four inche^ in circumference, whilil its blanches cvcrfhadowed a fpace of more than 100 feet in diameter ! I'his tree he affures that he could have kicked over. The country, according to his ac- count, is not exempted from (lorms. He is himfclf a French philofopher. What a pity then is it that he did not explain to thofe, who have not had the benefit of being enlightened in that fchool, upon what principle of mechanics or ftatics the tree could refill the violence of the elements till it arrived at fo enormous a fiz.e ? ALPHONSUS X. king of Leon and Caftile (fee Encycl.) This prince underftood ailronomy, philolo- phyv and hiltory, as if he liad been only a roan of let- ters ; and compofed books upon the motions of the heavens, and on the hillory of Spain, which are highly commended. "What can be more furprifing (lays Mariana), than that a prince, educated in a camp, and nar.dlliig arms from his childhood, fliould have luch a knowLdge of the ftars, of philofophy, and the tranfac- tions of the world, as men of leiiure can fcarcely ac- quire in their retirements? There are extant fome books of Alphonfus on the motions of the ftars, and the hif- tory of Spain, written with great fl as in fig. i. Nor is it unlikely that fuch a fituation of ftones as Is repre- feiited in fig. z. would not unfrcquently occur by acci- dent to raafons. This could hardly fail of exciting a little attention and refieftion. It was a pretty obvious refleftion, that the (lones A and C, by overhanging, leaned sgainil the intermediate ftone B, and gave it fome fupport, and that B cannot get down without thrufling afide A and C, or the piers which fupport them. This was an approach to the theory of an arch; and If this be combined with the obfervation of fig. i. we get the difpofulon reprcfented in fig. 3. having a perpendicular joint In the middle, and \\\t prhic'ipU of the arch is completed. Obferve that this Is quite diffe- rent from the principle of the arrangement in fig. 1. In that figure the ftones aft as wedges, and one cannot get down without thrufling the rell afide; the fame principle obtains in fig. 4. confilllng of five arch ftones ; but in fig. 3. the Hones B and C fupport each other by their mutual preffure (independent of their own weight), arlfing from the tendency of each lateral pair to fall outwards from the pier. This is the principle of the arch, and woiald fupport the key-Hone of fig. 4. although each of its joints were perpendicular, by rea- fon of the great friction arifing from the horizontal thruft exerted by the adjoining Hones. This was a moft Important dlfcoveiy in the art of building ; for now a building of any width may be roofed with flone. We are difpofed to give the Greeks the merit of this difcovcry ; for we obferve arches in the moll ancient buildings of Greece, fuch as the temple of the fun at Athens, and of Apollo at Dldymos ; not indeed as roofs to any apartment, nor as parts of the ornamental defign, but concealed in the walls, covering drains or other neceffary openings ; and we have not found any real arches in any monuments of ancient Perfia or E- gypt. Sir John Chardin fpeaks of numerous and ex- tenfrve fubterranean paffages at Tchllminar, built of the moft exqulfite mafonry, the joints fo exaft, and the ftones fo beautifully dreffed, that they look like one continued piece of polifhed marble : but he nowhere fays that they are arched; a circuniftance which we Ar.h. think he would not have omitted — no arched door ' v —^ or window is to be ften. Indeed one of the tombs is faid to be arch-roofed, but it is all of one folld rock. No trace of an arch is to be feen in the ruins of ancient Egypt ; even a wide room is covered with a fingle block of ftone. In the pyramids, indeed, there are two galleries, whofe roofs confift of many pieces; but their conftructloij puts it beyond doubt that the builder did not know what an arch was : for it Is co- vered in the manner reprefented in fig. 5. where every piojecting piece Is piore than balanced behind, fo that the whole awkward mafs could have ftood on two pil- lars. The Greeks therefore fcem entitled to the honour of the invention. The arched dome, however, feemsto have arifcn in Etruria, and originated In ail probability from the employment of the augurs, whofe bufine'fs it was to obferve the flight of birds. Their ftatlons for this purpofe were templi, fo called a tcmplando, " on the fuminits of hills." To Ihelter fuch a perfon from the weather, and at the fame time allow him a full profpcft of the country around him, no building was fi) proper as a dome fet on columns; which accordingly Is the figure of a temple in the moft ancient monuments of that coun- try. We do not recolleft a building of this kind in Greece except that called the Lanlbfrn of Da>wjlhenes, which Is of very late date, whereas they abounded in Italy. In the later monuments and coins of Italy or of Rome, we commonly find the Etrufcan dome and the Grecian temple combined \- and the famous pantheon was of this form, even In its moft ancient ftatc. It does not appear that the arch was confidercd as a part of the onmnienlal archltcdure of the Greeks during the time of their independency. It Is even doubtful whether it was employed in roofing their temples. In none of the ancient buildings where the roof Is "-one, can there be feen any rubblfii of the vault, or mark of p, the fpring of the arch. It is not unfrequcnt, however. It was nfcd after the Roman conquefts, and may be feen In Athens *' ''''" ""'/ Delos, Palmyra, Balbek, and other places. It is very "^.^''j*'^" frequent in the magnificent buildings of P..ome ; fuch dudls.''"'' as the Collfeum, the baths of Dioclefian, and the tri- umphal arches, where its form is evidently made the objeft of attention. But its chief employment was In bridges and aquediifts ; and It is in thofe works that Its Immenfe utility is the moft confplcuous : For by this happy contrivance a canal or a road may be carried acrofs any ftream, where it would he almoft impofiible to erect piers fufficiently near to each other for carry, ing lintels. Arches have been executed i ^50 feet wide, and their execution demonllrates that they may be made four times as wide. As fuch ftupendous arches are the greateft perform- niffia°ty ances of the mafonic art, fo they are the moft difficul: of conftruc- and delicate. When we refleft on the immenfe quan-""B"- tity of materials thus fufpended in the air, and compare this with the fmall cohefion which the firmeft cement can give to a building, we fliall be convinced that It is not by the force of the cement that they are kept to- gether : they Hand faft only In confequence ot the proper balance of all their parts. Therefore, in order to ereft them with a well-founded confidence of their durability, this balance ftiould be well underftood and jiidlcioufly employed. We doubt not but that this was underftood in fome degree by the engineers of antiqui- ty.. ARC [ i6 1 ARC A:i-h. ty i but they have left us none of their knowledj^e. Iccii the magnificent vaultings of the temple of Mars the They muft have had a great deal of mechanical know. Avenger, and the temple of Peace at Rome, the tliruft3 Arch. ,.1-11 "4 It du'e before they could ercft the magnificent and beau- of which are withilood by two mafles of folid wall, niv'c't^es tiful buildings whofe ruins ftill enchant the world ; but which join the iide walls of the temple at right angles. -of the Die. they kept it among themfelves. We know tiiat the njfiaca. Dionyfiacs of Ionia were a great corporation of archi- tefts and engineers, who undertook, and even monopo- lized, the building of temples, iladiums, and theatres, nrecifely as the fraternity of mafons in the middle ages monopolized the building of cathedrals and conventual • churches. Indeed the Dionyfiacs refcmblcd the myili- cal fraternity now called free mafons in*many important particulars. They allowed no ilrangers to inlcrtere in and extend i'ldewife to a great ditlance. It was evident that the walls of the temple could not yn'eld to the pref- fure of the vaulting without pufliing thefe immejife but- trefles along their foundations. He therefore placed four buttrcfles to aid his piers. They are almoll folid maflcs of ftone, extending at lead 90 feet from the piers to the north and to the fouth, forming as it were the fide walls of the crofs. They effeflually fecured them from the thruils of the two great arclies of the nave their employment; they recognlfed eacli other by figns which fupport the dome ; but there was no fuch pro- and tokens; they profefTed certain myfterious doctrines, vifioii agair.ft the pulh of the great north and fouth under the tuition and tutelage of Bacchus, to whom arches. Anthcmius trulled for this to the half dome, they built a magnincent temple at Teos, where they ce- which covered the feniicircular eaft end of the church, lebratedhismyfteries asfolemn feftivals; and they called and occupied the whole eailern arch of the great dome, all other men profane, becaufo not admitted to thefe But when the dome was liniflicd, and had ftood a few niyfteries. But their chief myfteries and mod inipor- months, it pufhcd the two eaftcrn piers with their but- ' ■ . • ' > > trefTes from the perpendicular, making them lean to the cdllward, and the dome and hall dome fell in. Il'idorus, W'ho fucceeded to the charge on the death of Anthe- raius, ftrengthened the piers on the call fide, by filling up fome hollows, and again raifed the dome. But tant fecrcts feem to be their mechanical and mathema- tical fciences, or all that academical knowledge which forms the regular education of a civil engineer. We know that the temples of the gods and the theatres re quired an immenfe apparatus of machinery for the cele- 1% The art of blli'tiiiii^ arches un- derftood in bration of fome of their myfteries ; and that the Dio- things gave way before it was clofcd ; and while they iiyfiacs contrafted for thofe jobs, even at far diftant were building in one part it was falling in in another, places, where they had not the privilege of building the The pillars and walls of the eaftern femicircular end edifice which was to contain them. This is the moft were much ihattered by this time. Ifidorus feeing that likely way of explaining the very fmall quantity of m.e- they could give no refinance to the pufli which was fo chanical knowledge that is to be met with in the wri- evidently direfted that way, erefted fome clumfy but- tings of the ancients. Even Vitruvius does not appear trcfies on the eaft wall of the fquare which furroundei to have been of the fraternity, and fpeaks of the Greek the whole Greek crofs, and was roofed in with it, form- architefts in terms of refpeft next to veneration. The ing a fort of cloifter round the whole. Thefe buttrefTes, CoIUgium Murarioium, or incorporation of mafons at fpanning over this cloifter, leaned againft the piers of Rome, does not feem to have fliared the fecrets of the the dome, and thus oppofed the thrufts of the great Dionyfiacs. north and fouth arches. The dome was now turned The art of building arches has been moft afiiduoufly for the third time, and many contrivances were adopted cultivated by the aflbciated builders of the middle ages for making it extremely light. It was made ofFenfively of the Chriftian church, both Saracens and Chriftlans, flat ; and, except the ribs, it was roofed with pumice the middle 3'"^ '^"^y ^^^™ t° \\ii\e. indulged in it with fondnefs : ftone ; but, notwithftanding thefe precautions, the ages they multiplied and combined arches without end, arches fettled fo as to alarm the architedls, and they placing them in every poflible fituation. made all fure by filling up the whole from top to bottonx Having ftudied this branch of the art of building with arcades in three ftoiies. I'he loweft arcade was very with fo much attention, they were able to ereft the lofty, lupported by four noble marble columns, and thus moft magnificent buildings with materials which a prefervcd, in fome meafuie, the church in the form of 1^ Greek or Roman architeA could have made little or a Greek crofs. The ftory above formed a gallery for Better than no ufe of. There is infinitely more fcientific (liill dlf- the women, and had fix columns in front, fo that they l>y t'i= played in a Gothic cathedral than in all the buildings did not bear fair on thofe below The third ftory was Greeks and ^£ Q^eece and Rome. Indeed thefe laft exhibit very a dead wall filling up the arch, and pierced with three little knowledge of the mutual balance of arches, and rows of fmall ill-fhaped windows. In this un workman- are full of grofs blunders in this refpedt ; nor could like ftiape it has ftood till now, and is the oldeft church they have refifted the fhock of time fo long, had they in the world; but it is an ugly mifhapen mafs, more re- not been almoft folid maffes of ftone, with no more ca- fenabling an overgrown potter's kiln, furrounded with vity than was indifpenfably ncceffary. furnaces pieced and patched, than a magnificent temple, Anthemius and Ifidorus, whom the Emperor Jufti- We have been thus particular in our account of it, be- nian had felefted as the moft eminent architefts of caufe this hiftory of the building (hows that the ancient 14 Befea* of the chur h of St of St Sophia Qreece for building the celebrated church of St Sophia architects had acquired no diftindl notions of the aflion tL I" " at Conftantinople, feem to have known very little of of arches. Almoft any mafon of our time would know. tinople. :>ple; this matter. Anthemius had boafted to Juftinian, that that as the fouth arch would pulh the pier to the eaft- he would outdo the magnificence of the Roman pan- ward, while the eaft arch puftied it to the fouthward, theon, for he would hang a greater dome than it aloft the buttrefs which was to withftand thefe thrufts muft in the air. Accordingly he attempted to raife it on not be placed on the fouth fide of the pier, but on the the heads of four piers, diftant from each other about fouth-eaft fide, or that there muft be an eaftern as well J 15 feet, and about the fame height. He had probably as a fouthern buttrefs. No fuch blunders are to be feen Such as an never foun in a Gothi church. \ i6 ARC [ I in « Gothfc calliedral. Some of them appear, to a care- lefs fpeftator, to be very maffive and clumfy ; but when jiidlcioufly examined, they will be found very bold and light, being pierced in every direftion by arcades, and the walls are divided into cells like a honeycomb, fo that they are very lliff, while they are very light. About the middle, or rather towards the end, of lad century, when the Newtonian mathematics opened the road to true mechanical fcience, the conflrnftion of archescngroffed the attentionof the firllmalhematicians. DrHookc'sThc tirft hint of a principle that we have met with is principle of Dr Hooke's affcrtion, that the figure into which a ciiain arches ^^ rope, perfedly flexible, will arrange itfelf when fuf- pended from two hooks, is, when inverted, the proper form for an arch compnfed of ftonesof uniform weight This he affirmed on the fame principle which is made ufe of in the Encyclopaedia Britannica in the article Roof, § 25. viz. that the figure wliicli a flexible fef- toon of heavy bodies alTumes, when fufpended from two points, is, when inverted, the proper form for an arch of the fame bodies, touching each other in the fame points ; becaufe the forces with which they mutually prefs on each other in this laft cafe, are equal and op- pofite to the forces with which they pull at each other in the cafe of fufpenfion. This principle is ftriftly jull, and may be extended to every cafe which can be propofed. We recofieft fee- ing it propofed, in very general terras, in the St James's Chronicle in 1759, when plans were forming for Black- friar's Bridge in London ; and fince it is perhaps equal, in practical utility, to the moft elaborate inveftigations of the mathematicians, our readers will not be difpleafed with a more particular account of it in this place. Eipllmed, Let ABC (fig. 6.) be a parcel of magnets of any fizc and fliape, and let us fuppofe that they adhere with great force by any points of contaft. They will com pofe fuch a flexible feiloon as we have been fpeaking of, if fufpended from the points A and C. If this fi- gure be inverted, preferving the fame points of contaft, they will remain in equilibrio. It will indeed be that kind of equilibrium which will admit of no difturbance, and which may be called a tottering equilibrium. If the form be altered in the fmallell degree, by varying the points of contaft (which indeed are puints in the^^ur; of equilibration), the magnets will no more recover their former pofition than a needle, which we had made to Hand on its point, will regain its perpendicular pofition after it has been difturbed. But if we fuppofe planes de,fg, hi, &c. drawn, that the points of mutual contaft a, b, c, each bifefting the angle formed by the lines that unite the adjoining con- latts (fg, for example, bifefting the angle formed by a b, be), and if we fuppofe that the pieces are changed for others of the fame weights, b\it having flat fides, which meet in the planes de,fg, hi, &c. it is evident that we fhall have an arch of equilibration, and^that the arch will have fome liability, or will bear a little change of form without tumbling down : for it is plain that the equilibrium of the original feftoon obtained only in the points a, b, c, of contaft, where the preffures were perpendicular to the touching furfaces; therefore if the curve a, b, c, ftill paffes through the touching furfaces perpendicularly, the conditions that are required for equilibrium fl;ill obtain The cafe is quite fimilar to that of the (lability of a body relling on a horizontal SuppL. Vol. I. Part I. Ar.'S. 7 ] ARC plane. If the perpendicular through the centre of gra- vity fails within the bale of the bbdy, it will not only *" ftand, but will require fome force to purti it over. In the original felloon, if a fmall weight be added in any part, it will change the form of the curve of equilibra. tion a little, by changing the points of mutual contaft. This new curve will gradually feparate from the former curve as it recedes from A or C. In like manner, when the fciloon is fet up as an arch, if a fmall weight be laid on any part of it, it will bring the whole to the ground, becaufe the (hifting of the points of contaft will be juft the contrary to what it fliould be to fuit the new curve of equilibration. But if the fame weight be laid on the fame part of the arch now conftruftcd with flat joints, it will be fuftained, if the new curve of equilibration IHII palfes through the touching furfaces. Thefe conclufions, which are very obvioufly dedu- cible from the principle of the teftoon, (hew us, without any further dilcuflion, that the longer the joints are, the greater will be the (lability of the arch, or that it will require a greater force to break it down. There- fore it is of the greatcll importance to have the arch ftones as long as economy will permit; and this was the great ufe of the ribs and other apparent ornaments in the Gothic architefture. The great projeftionsof thofe ribs augmented their ftiffnefs, and enabled them to fup- port the unadorned copartments of the roof, compofed of very fmall Hones, fcldom above fix inches thick. Many old bridges are dill remaining, which are ftrength- ened in the fame way by ribs. Having thus explained, in a very familiar manner, the liability of an arch, we proceed to give the fame popular account of the general application of the prin- ciple. _ _ ,8 Suppofe it to be required to afcertain the form of an And ap. arch which fliall have the fpan AB (fig. 7.), and theplied. height F 8, and which (hall have a road-way of the di- menfionsCDE above it. Let the figure ACDEB be inverted, fo as to form a figure KedeV). Let a chaia of uniform thicknefs be fulpended from the points A and B, and let it be of fuch a length that its lower point will hang at, or rather a little below, f, corre- fponding to F. Divide AB into a number of equal parts, in the points 1, 2, 3, &c. and draw vertical lines, cutting the chain in the correfponding points 1, 2, 3, Sec. Now take pieces of another chain, and hang them on at the points 1,2,^, &c. of the chain A/B. This will alter the form of the curve. Cut or trim thefe pieces of chain, till their lower ends all coincide with the inverted road-way eil e. The greater lengths that are hung on in the vicinity of A and B will pull down thefe points of the chain, and caufe the middle pointy (which is lefs loaded) to rife a little, and will bring it near to its proper height. It is plain that this procefs will produce an arch of perfeft equilibration ; but fome farther confiderations are neceflfary for making it exaftly fuit our purpofe. It is an arch of equilibration for a bridge, that is fo loaded that the weight of the arch-dones is to the weight of the matter with which the haunches and crown are loaded, as the weight of the chain A/B is to the fum of the weights of all the little bits of chaia very nearly. But this proportion is not known before- hand ; we mud therefore proceed in the following man- ner : Adapt to the curve produced in this way a thick- C neff ARC [ i8 ] ARC Arch. '9 . The chief defea of the curve found ac- cording Vt this prin- ciple. ticTsof theareh-ftones as great as are tlioiiglit fnflicient to enfurc (lability ; then compute the weight of the arch ftones, and the weight of the gravel or rubbifh with ■which the haunches are to be filled up to the rOad-way. Jf the proportion of thefc two weights be the fame with the proportion of the weights of chain, we may reft fa- tisfied with the curve now found ; but if different, we can calily calculate how much mull be added equal to, or taken from, each appended bit of chain, in order to make the two proportions equal. Having altered the appended pieces accordingly, we (hall get a new curve, which may perhaps require a very fmall trimming of the bi's of chain to make them (it the road-way. 'ihis curve will be iniinitely near to the curve wanted. We have praftifed this method for an arch of 62 feet fpan and it feet height, the arch-llones of which were only two feet nine inches long. It was to be loaded with gravel and fhivers. We made a previous computation, on the fuppofition that the arch was to be nearly elliptical. The didance between the points J, 2, 3, &c. were adjufted, fo as to determine the pro- portion of the weights of chain agreeable to the fuppo- fition. The .curve differed coniiderably from an ellipfe, making a confiderable angle with the vertlcles at the fprirg of the arch. The real proportion of the weights of chain, when all was trimmed fo as to fuit the road- way, was confiderably different from what was expect- ed. It was adjulled. The adjuRment made very little change in the curve. It would not have changed it two inches in any part of the real arch. When the procefs was completed, we conllruilcd the curve ma- thematically. It did not differ fenfibly from this mecha- nical con(lrui£lion. This was vei-y agreeable informa- tion ; for it (hewed us that the firft curve, formed by about two hours labour, on a fuppofition confiderably different from the truth, would have been fufficiently exaft for the purpofc, being in no place three inches from the accurate curve, and therefore far within the joints of the intended arch-llones. Therefore this pro- cefs, which any intelligent mafon, though ignorant of mathematical fcience, may go through with little trouble, will give a very proper form for an arch fub- jeCl to any conditions. The chief defeft of the curve found in this way is a want of elegance, becaufe it does not fpring at right angles to the horizontal line ; but this is the cafe with all curves of equilibration, as we fhall fee by and by. It is not material: for, in the very neighbourhood of the piers, we may give it any form we pleafe, becaufe the mafonry is folid in that place ; nay, we apprehend that a deviation from the curve of equilibration is proper. The conflruflion of that curve fuppofcs that the pref- fure on every part of the arch is vertical ; but gravel, rarth, and rubbilh, exert fomewhat of a hydroilatical prefTure laterally in the ail of fettling, and retain it afterwards. This will require fome more curvature at the haunches of an arch to balance it ; but what this lateral prefTure may be, cannot be deduced with confi- dence from any experiments that we have feen. We are inclined to think that if, inllead of dividing the ho- rizontal line AB in the points i, 2, 3, &c. we divide the chain itfclf into equal parts, the curve will ap- proach nearer to the proper form After this familiar ftatement of the general principle, it is now time to confider the theory founded on it more in detail. This theory aims at fuch an adjuft- Arch, ment of the pofition of the arcii-dones to the load on ——v— ' every part of the arch, that all (hall remain in cquili-.j-, ^^° brio, although the joints be perfcAly polifhed, and with- founded ok out any cement. The whole may be reduced to two tliis i>rin. problems. The firft is to determine the vertical pref-'^T''* fure or load on every point of a line of a given form, which will put that line in equilibrio. The fecond is to determine the form of a curve which (liall be in equi- librio when loaded in its different points, according to any given law. The whole theory is deducible from § 2J. of the ar- tide Roof. The fundamental propofition in that fec- tion dates the proportions between the various prelfures or thrulls which are exerted at the angles of an aflem- blage of beams or other pieces of folid heavy matter, 1 freely moveable about thofe angles, as fo m.any joints, ( but retaining th^ir pofition by the equilibrium of thofe >' prelTures. It is there demondrated, " that the thruft '■ at any angle, if edijnated in a horizontal direflion, is the fame throughout, and may be reprefcnted by any ho- rizontal lineBT.fig.S. ( Roofs, fig. 10 Pl.CCCCXL)s and that if a vertical line Ql^S be drawn through T, the thruft exerted at any angle D by the piece CD, in its own direction, will then be reprefcnted by BR, drawn parallel to CD ; and in like manner, that the thruft in the direiftion ED is reprefcnted by BS, &c.; and, ladly, that the vertical thrulls or loads, at each angle B, C, D, by which all thefe others prefTures are excited, are reprei^ented by the portions QC, CR, RS, of the vertical intercepted by thofe lines ; that is, all thefe preffures are t9 the uniform horizontal thrud as the lines which rtprefent them are to BT. The hori- zontal thrud, therefore, is a very proper unit, with which we may compare all the others. Its magnitude is eafily deduced from the fame propofition ; for QS is the fum of all the vertical preflures of the angles, and therefore reprefents the weight of the whole affem- blage. Therefore as QS is to BT, fo is the weight of the whole to the horizontal thrud. n , To accommodate this theory to the conftruftion of ^""n"""^ a curvilineal arch vault, let us fird fuppofe the vault to'''''"i^ *°''*' be polygonal, compofed of the cords of the elementary ..jy',, ^f ^„ arches. Let AVE (fig. 9.) be a curvilineal arch, ofarch vaultj, which V is the vertex, and VX the vertical axis, which i we fhall confider as the axis or abfcilTa of the curve, while any horizontal line, fuch as HK, is an ordinate to the curve. About any point C of the curve as a centre defcribe a circle BED, cutting the curve in B and D. Draw the equal cords CB, CD. Draw alfo the horizontal line CF, cutting the circle in F. De- fcribe a circle BCDQ__paffing through B, C, D- Its centre O will let in a line COQ_^ which bifedls the angle BCD ; and C d, which touches this circle in C, will bifedl the angle bCd, formed by the equal cords BC, CD. Draw CLP perpendicular to c b, and DP perpendicular to CD, meeting CL in P. Tbrougli L draw the tangent GLM, meeting CD in G, and the vertical line CM in M. Draw the tangent F a, cutting the cords BC, CD, in b and d, and the tangent to the circle BCDQjn c. Ladly, draw <^/ N parallel to be. From what is demondrated in § 27. of lie article Roof, it appears, that if BC, CD be two pieces of an equilibrated heavy polygon, and if CF reprefent the ho- rizontal thruft in every angle of the polygon, C d and Cb ARC [ Arch. C b will fcverally rcprcfciit the thruHs exerted by the — V— 'piecL's DC, BC, and that Id, or CN, will reprefciit the weiiJ-ht lying on the angle liCD, by which tlujfe thrufts are balanced. As the reader may not have the article Roof at hand, this equilibrium may be recalled to his remem- brance in the following manner : Produce c/C to o, io that Co may be equal to C./. Draw bn to the verti- cal parallel to dV>, and join no. It Is evident that inoC is a parallelogram, and that «C ( = ^(/) := CN. Now the thrufi. or fupport of the piece BC is exerted I'n-the direftion Ct, while that of DC is exerted in the diretUon Co. Thefe two thrulls are equivalent to the thruft In the diagonal Cn ; and It is with this com- pound ihruft tliat the load or vertical prelTure CN Is in immeiliate equilibrium. Becaufe iCL, NCF, are right angles, and FCL is common to both, the aiigks 3CF and MCL are equal. Therefore the right angled triangles iCF and MCL are finiilar. And fmce CF is equal to CL, cb is equal to CM. It Is evident that tlie triangles GCM and ^CN are fimilar. Therefore CG : C ^/ = CiNI : CN, CbXCJ -Qb:Cn. Therefore we have CN = —gQ- . But becaufe CDP and CLG are right angles, and therefore C([Uil, and the angle GCP Is common to the two tri- angles GCL, PCD, and CD Is equal to CL, we have CbxCd CG equal to CP. Therefore CN = ^p . Alfo, fince CDP Is a right angle, DP meets the diameter in (3 , the oppofite point of the circumference, and the angle DQC is equal to DCd, or DC^ (becaufe bCd is bifefted by the tangent), that is, to PCQ^ (becaufe the right angles ^CP, cDO are equal, and cDP Is common). Therefore PQ_^Is equal to PC ; and If PO be drawn perpendicular to CQ__, it will bifeCl It, and O is the centre of the circle BCDQB. Now let the points B and D continually approach to C (by diminifhlng the radius of the fmall circle), and ultimately coincide with It. It is evident that the circle BCDQ__is ultimately the equlcurve circle, and that PC ultimately coincides with OC, the radius of curvature. Alfo C b XC d becomes ultimately C c'. Therefore CN, the vertical load on any point of a Ct'' curve of equilibration, is =: Rad. Curv. It Is farther evident, that CF is to Cc as radius to the fecant of the elevation of the tangent above the ho- rizon. Therefore we have the load on any point of .,, , .• 1 . Sec' Elev. the curve always proportional to — Rad. Curv. This load on every elementary arch of the wall Is commonly a quantity of folld matter Incumbent on that element of the curve, and prefiing it vertically; and it may be conceived as made up of a number of heavy lines Handing vertically on it. Thus, if the element 'Ee of the curve were lying horizontally, a little parallelo- gram RE(?r Handing perpendicularly on It, would re- prefent its load. But as this element E e has a floping pofition, it is plain that, in order to have the fame quantity of heavy matter prefiing it vertically, the height of the parallelogram muil be Increafed till it meets in s p, the line R t drawn parallel to the tangent EG. It is evident that the angle REp is equal to the Aich, «1 19 ] ARC angle AEG. Therefore we have ER : Ep := Rad. : Sec. Elev. ' If therefore the arch is kept in equillbrio by the ver- tical prellurc of a wall, we mud have the height of the wall above any point proportional to - ^!iI^-1^.1l. Rad. of Curv. Cor. I. If OS be drawn perpendicular to the verti- Corollaries, cal CS, CS will be half the vertical cord of the equl- curve circle. I'he angle OCS is equal to ^rCF, that Is, to the angle of elevation. Therefore 1 : .Sec. Elev. = CS : CO, and the fecant of elevation may be expref. . , , CO . C05 fed by -p^, and its cube by -^^rj. Thereforethe height f 11 • .- 1 . C03 CO' or wall is proportional to _-_ — _ — , or to ^, or CS^XCO C S •* CO' Sec' of Elev. CS'XCS' °^ ° Vert. Cord of Curv. Cor. II. If we make the arch VC =: z, the abfcIflU VH = .v, the ordinate TrLC^zy, the radius ofculi CO = /-, and the 4 vertical cord CS = .r, the height of wall pref- fing on any point Is proportional to -^; or to -: — , or Therefore, when the equation of the curve «'+y' y f . . ^_ is given, and the height of wall on any one point of it is alfo given, we can determine it for any other point; for the equation of the curve will always give us the re- lation of z, X, and ji, and the value of r or s. This may be iUuftrated by an example or two. For this purpofc it will generally be moil convenient to affume the height above the vertex V for the unit of computation. The thicknefs of the arch at the crown is commonly deter- mined by other circumllances. At the vertex the tan- gent to the arch Is horizontal, and therefore the cube of the fecant Is unity or i. Call the height of wall, at the crown, H, and let the radius of curvature in that point be R, and Its half cord R (it being then coinci- dent with the radius), and the height on any other Z.5 point h. We have-jr- ; -^ = H : /i, and ^ = H X -r- R. ySr y^ R . i' R X — . The other formula gives h = Hx -^X — . Examp. I. Suppofe the arch to be a legment of afiuitrated circle, as in fig. 10. where AE is the diameter, and O by exam- the centre. In this arch the curvature is the fameP'^*- R z3 throughout, or — = i. Therefore A =: H X ^-, or y' = H X Cube Sec Elev. This gives a very fimple calculus. To the logarithm of H add thrice the logarithm of the fecant of elevation, The fum Is the logarithm of h. It gives alfo a very fimple conftruftlon. Draw the vertlcalCS, cutting the horizontal diameter In S. Draw ST, cutting the radius OC perpendicularly In T. Draw the horizontal line Ta, cutting the vertical In 2. Join %o. Make C«= V'y, and draw ux parallel to zo. Cc mud be made =: Car. The demonllration is evident. It is very eafy to fee that if CV is an arch of 60°, and Vu is -rjth of VC, the points v and c will be on a level ; for the fecant of CV is twice CO, and there- fore Cf is 8 times Vv, which is -yth of VH, C 2 The ARC [ 20 ] ARC Arch. Tlie dotted line r^i/ is drawn according to this ""~^'~~~' calculus or conftruftion. It falls confiderably below the horizontal line in the neighbourhood of c ;■ and then, pafling very obliquely through (, it rifes rapidly to an uniTieafurable lieight, becaiife the vertical line through A is its aiTymptote. This muft evidently be the cafe with ever\' ciiive which fprings at right angles with a horizontal line. It is plain that if ■uV be greater, all the other ordi- nates of the cinve vg cf, relling on tlie circumference AVE, will be greater in tlie fame proportion, and the curve will cut the horizontal line drawn through v in fonie point nearer to v than c is. Hence it appears that a circular arch cannot be put in eqnilibno by building on it up to a horizontal line, whatever be its fpan, or whatever be the thicknefs at the crown. We have feen that when this thicknefs is only ^Vth of the radius, an arch of 120 degrees will be too much loaded at the flanks. This thicknefs is much too fmall for a bridge, being only ^V'h of the fpan CM, whereas it fhould have been almoft double of this, to bear the in- equalities of weight that may occafionally be on it. When the crown is made ftill thinner, the outline is ftill more deprelTcd before it rifes again. There is there- fore a certain fpan, with a correfponding thicknefs at the crown, which will deviate leail of all from a hori- aontal line. This is an arch of about 54 degrees, the thicknefs at the crown being about one-fouith of the fpan, which is extravagantly great. It appears in ge- neral, therefore, that the circle is not a curve fuited to the purpofes of a bridge or an arcade, which requires an outline nearly horizontal. Examp. 2. Let the curve be a parabola AVE (fig. 11.), cf which V is the vertex, and DG the direftrix. Draw the diameters DCF, GVN, the tangents CK, VP, and the ordinates VF and CN. It is well known that GV .- is to DC as VP'- to CK% or as CN^ to CiO. Alfo 3 GV is the radius of the ofculating circle at V, and 3 DC is one-half of the vertical cord of the ofculating circle at C. Therefore CN' : CK^ (ory :i,^) = K:s, ' t -y * R and J = ^ R. But Cc, or A = H X -. . Therefore The convcrfe of the problem, namely, to find the Arch. form of the arch when the figure of the b.ick of it is ~"^ "^ given, is the moft ufual queftion of the two, at lead in-p^^ ^^. i^ cafes which are moll important and moft difficult. Of f,,rm of an thcfe perhaps bridges arc the cliief. Here the neceffi-arcli when ty of a road- way, of eafy and regular afcent, confines '^"^ ''S'"'* us to an outhne nearly horizontal, to which the curve"' ''* ^^''^ of the arch muft be adapted. This is the moft difficult problem of the two ; and we doubt whether it can be folved without employing infinite approximating fcrie- fes inftead of accurate values. Let ai)e (lig. 12.) be the intended outline or cx- tra^los of the arch AVE, and let 7)Q_be the common axis of both curves. From c and C, the correfponding points, draw the ordinates ch, CH. Let the thicknefs i)V at the top be a, the abfcifTa -uhhe = u, and VH =: X, and let the equal ordinates c h, CH be y, and the arch VC be 2. Then, by the general theorem, cC zr -. — , ;• being the radius of curvature. This, by tte common rules, is Z5 y X — X y This gives C = y-- ■X y yi X C ; where C is a conftant quantity, found by taking the real value of cC in V, the vertex of the curve. But it is evident that it is alfo = a + « u. Therefore a -{- x — u =: X X fluxion of ^. _ yx. .xc;=5 h = Hx R ^ — R = H X R H. Therefore Cr = TV. It follows from this inveftlgatlon, that the back or extrados of a parabolic arch of equilibration muft be parallel to the arch or foffit itfelf; or that the thicknefs of the arch, eftimated in a vertical direAion, muft be equal throughout ; or that the extrados is the fame pa- rabola with the fofiit or intrados. We have feleftcd thefe two examples merely for the fimplicity and perfpicuity of the folutions, which have been eifefted by means of elementary geometry only, inftead of employing the analytical value of the radius of the ofculatory circle, viz. — If we now fubftitute the true value of a (which is given, becaufe the extrados is fuppofed to be of a known form), exprctTed in terms of j/, the refulting equation will contain nothing but x and y, with their firft and fecond fluxions, and known quantities. From this equa- tion the relation of.x-andjmuft be found by fuchmethods as feem beft adapted to the equation of the extrados. Fortunately the protefs is more fimple and eafy in the moft common and ufeful cafe than we fhould ex- peft from this general rule. We mean the cafe where the extrados is a ftraight line, efpecially when this is horizontal. In this cafe u is equal to 0. Example. To find the form of the balanced arch AVE (fig. 13-)) having the horizontal line cv for its extrados. Keeping the fame notation, we have u =z 0, and C . . r* therefore a + x =— X fluxion of r-. y y C Aflume V = — ; then — = », and t- X fluxion of -r , _ ■" y , y y Cvv , , Cvv T,, r • . • =: — — , that IS a + x = — : — 1 heretore ax + xx yx — xy have involved us at leaft in the elements of fecond fluxions. We have alfo preferred fimplicity to ele- gance in the inveftigation, becaule we wifh to inftrudl the pra£lical enginee;, who may not be a proficient in the higher mathematics. -^, which would —C-u'-o; and by taking the fluents, we have 2a«+x* y2 a X + x^ p . Conlequently, = C and 9-=— I being =— 1. of this, we have y =z ^ C Taking the fluent X L {2 ax + 2 x» ARC [ " J^ i \/ 2ax + X-). But at the vertex, where x = o, 'we havey = v^ C X L (2a). The correfted fluent is therefore v = v' C X L — ' ,1 It only remains to find the conftant quantity C. This we readily obtain by felefting Come point of the cxtrados where the values of x and y are jjiven by par- ticular circumftaiices of the cafe. Thus, whcji the fpan 2 s and height li of the arch a rc gi ven, we liave quentlyv'C=: — j, and confe- Therefore the general value ofyzzs X / fl + « + \/2 ax_+_ XL 'a -\-h -\- >/ 2a Ij -J- h a As an example of the ufe of this formula, we fubjoin » table calculated by Dr Hutton of Woolwich for an arch, the fpan of which is i oo feet, and the height 40; whicli are nearly the dimenfions of the middle arch of Blackfriars Bridge in London. y X y X y K 6,000 21 10,381 ^6 2'.774 2 6.035 22 10,858 37 22,948 4 6,144 23 11,368 3« 24,190 6 6,324 24 1 1,911 39 25.505 8 6,580 2<, 12,489 40 26,894 10 6,914 26 13,106 4' 28,364 12 7.i.^o 27 13,761 42 29,919 r^ 7'37i 28 14.457 43 31.563 '4 7.Si34 29 15. '96 44 33.299 I? 8,i20 30 15,980' 45 35. '35 16 8,430 31 i6,8ii 46 37.'^75 17 ■ 8,766 32 17.693 47 39,126 18 9,168 33 18. 627 48 41.293 19 9.5 '7 34 19,617 49 43.581 20 9.934 .^5 20,665 50 46,000 The figure for this propofition is exaftly drawn ac- cording to thefe dimenfions, that the reader may judge of it as an objeft of fight. It is by no means deficient in gracefulnefs, and is abundantly roomy for the paffage of craft ; fo that no objedllon can be offered againft its ,, being adopted on account of its mechanical excellency . efefls of The reader will perhaps be furprifed that we have eCatcm made no mention of the celebrated Catenarian curve, »n curve, which is commonly faid to be the bell form for an arch ; but a little refleftlon will convince him, that although it is the only form for an arch confilting of ftones of equal weight, and touching each other only in fingle points, it cannot fuit an arch which mult be filled up in the haunches, in order to form a road-way. He will .be more furprifed to hear, atter this, that there is a certain thicknefs at the crown, which will put the Ca- tenaria in equilibrio, even with a horizontal road-way ; Arch, 17 theory ] ARC but this thicknefs is fo great as to make it unfit for a bridge, being fuch that the preffure at the vertex is *■ equal to the horizontal thruft. This would have been about 37 feet in the middle arch of Blackfriars Bridge. The only fituation, therefore, in which the Catenarian lorm would be proper, is an arcade carrying a lieight of dead Wall ; but in this fituition it would be very un- graceful. Without truubh'iig the reader with the in- velligation, it is fufficient to inform him that in a Ca- tenarian arch of equilibrati'jn the abfcilTa VH is to the abfciffd V h in the conltant ratio of the horizontal thrull to its exccfs above the prcflTure on- the vertex. This much will ferve, we hope, to give the reader alnutil'tj- of clear notion of this celebrated theory of the equilibrium'*'' '="'"- of arches, one of the moft delicate and important appli.'^''' .'5'^ cations 01 mathematical Icience. Volumes have been Oration, written on the fubjedt, and it Hill occupies the atten- tion of mechanicians. But we beg leave to fay, with great deference to the eminent perlons who have profe- cuted this theory, that their fpeculat ions have been of little fervice, and are little attended to by the pradi- tioner. Nay, we raay add, that Sir Chrillopher Wren, perhaps the moft accomplilhed archited that Europe has leen, fcems to have thought it of little value : for, among the fragments which have been prefcrvtd of his ftudies, there are to be feen fome imperfcd differtations on this very fubjedf , in which he takes no notice of this theory, and confiders the balance of arches in quite an- other way. Thefe are coUetied by th.e author of the account of Sir Chriftophcr Wren's family. This man's great fagacity, and his great experience in building, and, ftlU more his experience in the repairs of old and crazy fabrics, had (hewn him many things very inconfiftentr with this theory, which appears fo fpecious and fafe.' The general fads which occur in tlie failure of old arches are highly inftruttive, and deferve the moll care- ful attention of the engineer; for it is in this Hate that their defefts, and the procefs of nature in their dcllruc- tion, are moft diftindly fcen. We venture to alfirm,. that a very great majority of thefe fads are irreconcile- abie to the theory. The way in which circular arches commonly fail, is by the finking of the crown and the rifing of the flanks. It will be found by calculation, that in moft of the cafes it ought to have been jutl the contrary. But the deareft proof is, that arches very rarely fail where their load differs moll remarkably from that which this theory allov.'s. Semicircular arches have ftood the power of ages, as may be feen in the bridges of ancient Rome, ai:d in the numerous arcades which the ancient inhabitants have ereded. Now all arches which Ipring perpendicularly from tlie horizontal line, require, by this theory, a load of infinite height ; and, even to a confiderable diftance from the fpringino- of the arch, the load neccffary for the theoretical equili- briura is many times greater than what is ever laid on thofe parts ; yet a failure in the immediate neighbour- hood ol the fpring of an arch is a moil rare phenome- non, if it ever was obferved. Here is a moll remark- able deviation from the theory ; for, as is alreadv ob- ferved, the load is frequently not the fourth part of what the theory requires. Many other fads might be adduced which /hev» great deviations from the legitimate refults from the theory. We hope to be excufed, therefore, by the mathcmati- ciajis for doubting of the juftnefs of this theory. We dor ARC [2 do not tliink it erroneous, but dcfeflivc, leaving out circumftanccs which we apprehend to be of great im- \ti dtftfts. po"^"'^'-' i ^"^ "'"^ imagine that the dcfefts of the theory have arifen from the very anxiety of the mechanicians to make it perfei't. The arch-ilones are fuppofed to be perfeftly fmooth or pohlhed, and not to be connect- ed by any cement, and therefore to fullain each other merely by the equihbrium of their vertical preffnre. The theory enfures this equilibrium, and this only, leaving unnoticed any other caufcs of mutual aciion. The authors who have written on the fubjeft fay ex- prefsly, that an arch which thus fuftains itfclf muft be flronger than another which would not ; becaufe when, in imagination, we fuppofe both to acquire connexion by cement, the firft prcferves the influence of this con- nection unimpaired ; whereas in tlie other, part of the coheiiou is walled in coiniteraCting the tendency of fome parts to break ofl^ from the reil by their want of equilibrium. This is a very ipecious argument, and ■wouhi be juft, if the forces which are mutually exerted between the parts of the arch in its fettled ilate were merely vertical prelTures, or, where different, were in- confiderable in comparifon with thofe which are really attended to in the conftruftion. But this is by no means the cafe. The forms which the ufes for which arches are erefted oblige us to adopt, and the loads laid on the different points of the arch, frequently deviate conliderably from what are neceffary for the equilibrium of vertical preffures. The varying load on a bridge, when a great wagon paffes along it, fometimes bears a very feniible proportion to the weight of that point of the arch on which it rells. It is even very doubtful whether the preffures which are occa- fioned by the weight of the fluff employed for filling up the flanks really aft in a vertical direftion, and in the proportion which is fuppofed. We arc pretty certain that this is not the cafe with fand, gravel, fat mould, and many fubflances in very general ufe for this pur- pofe. When this is the cafe, the preffures fuflained by the different parts of the arch are often very iucon- fiflent with the theory — a part of the arch is over- loaded, and tends to fall in, but is prevented by the ce- ment. This part of the arch therefore afts on the re- moter parts by the intervention of the parts between, employing thofe intermediate parts as a kind of levers to break the arch in a remote part, jufl as a lintel would be broken. We apprehend that a mathematician would be puzzled how to explain the liability of an arch cut out of a folid and uniform mafs of rock. His theory conhders the mutual thrufls of the arch flones ao in the direftion of the tangents to the arch. Why fo ? be- caufe he fuppofes that all his polilhed joints are perpen- dicular to thofe tangents. But in the prefent cafe he has no exilling joints; and there feems to be nothing to direft his imagination in the affuraption of joints, which, however, are abfolutely neceffary for employing his theory, becaufe, without a fuppofition of this kind, there feems no conceiving anv mutual abutment of the arch ftones. Aflc a common, but intelligent, mafon what notion he forms of fuch an arch ? We apprehend that he will confider it as no arch, but as a lintel, which may be broken like a wooden lintel, and wdiich refills entirely by its cohefion. He will not readily conceive that, by cutting the under fide of a ftone lintel into an arched form, and thus taking away more than half of 29 2 ] ARC '^1 its fubflancc, he has changed its nature of a lintel, or Arch. given it any additional (Irength. Nor would there be any change made in the way in which Inch a inafs of flone would refill being broken down, if nothing were done hut forming the under fide into an arch. If the lintel he fo laid on the piers that it can be broken with- out its parts pufliing the piers afide (which will be t!ie cafe it it lies on the piers with horizontal joints), it w ill break like any other lintel; but if the joints are direcl- ed downwards, and converging to a point within tlie arch, the broken flone (fuppofe it broken at the crown by an overload in that part) cannot be prefl'ed down without forcing the piers outwards. Now, in this mode of afting, the mind cannot trace any thing of the fla- tical equilibrium that-we have proceeded on in the foregoing theory. The two parts of the broken lintel feem to pulh the piers afide in the fame manner that two rafters pufh outwards the walls of a houfe, when their feet are not held together by a tie-beam. If the piers cannot be pudied afide (as when the arch abuts on two folid rocks), nothing can prefs down the crown which does not crufli the flone. This conclufion will be ftriftly true if the arch is oF fuch a form that a fl:raight line drawn from the crown to the pier lies wholly within the folid mafonry. Thus if the vault confifl of two flraight flones, as in fig. r. or if it confill of feveral flones, as in fig. 14. difpofed in two flraight lines, no weight laid on the crown can deflroy it in any other way but by crufliing it to pow- der. But when flraight lines cannot be drawn from the When it i overloaded part to the firm abutments through the fo- f° ''^ ™" lid mafonry, and when the cohefion of the parts is notof jdj 5;^ able to withlland tlie tranfverfe flrains, we mufl call the der principles of equilibrium to our aid; and in order to employ them with fafety, we nuift confider how they are modified by the excitement of the cohering forces. The cohefion of the flones with each other by ce- ment or otherwife, has, in almofl every fituation, a bad effect. It enables an overload at the crown to break the arch near the haunches, caufing thofe parts to rife, and then to fpread outwards, jufl as a Manfarde or Kirb roof would do if the trufs beam which connefts the heads of the lower rafters were fawn through. This can be prevented only by loading that part more than is requifite for equilibrium. It would be prudent to do this to a certain degree, becaufe it is by this cohefion that the crown always becomes the weakell part of the arch, and fuffers more by any occafional load. We expect that it will be faid in anfwer to all this, that the cohefion given by the flrongefl cement that we can employ, nay, the cohefion of the flone itfelf, is a mere nothing in comparifon v\'ith the enormous thrulls that are in a Hate of continual exertion in the different parts of au arch. This is very true; but there is an- other force which produces the fame effett, and which increafes nearly in the proportion that thofe thruitsin- creafe, becaufe it arifes from them. This is the fridtion of the flones on each other. In dry freeflone this fric- tion confiderably exceeds one half of the mutual pref- fure. The refledling reader will fee that this produces the fame effeft, in the cafe under confideration, that cohefion would do ; for while the arch is in the aft of failing, the mutual preffure of the arch-flones is afting with full force, and thus produces a friftion more than adequate ARC [a adequate to all the effefts we have been ipeaking ■'of. , _ When thefe circumftances are confidered, we imagine that it will appear that an arch, when expofcd to a great overload on the crown (or indeed on any purt), divides, of itfcif, into a number of parts, each of which contains as many arch-ftones as can be pierced (fo to fpeak) by one ilraight line, and that it may then be confidered as nearly in the fame fituation with a poly- gonal arch of long (tones butting on each other like io many beams in a Norman roof (fee Roof, n° 49.), but without their braces and ties. It tends to break at all thofe angles ; and it is not fufficiently relifted there, becaufe the materials with which the flanks are filled up have fo little coliefion, that the angle feels no load except what is immediately above it ; whereas it fiiould be immediately loaded with all the weight which is dif- fufed over the adjoining fide of the polygon. This will be the cafe, even though the curvilineal arch be per- fectly equilibrated. We recolleft fome circumllances in the failure of a confiderable arch, which may be worth mentioning. It had been built of an exceedingly foft and friable ftone, and the arch (tones were too (hort. About a fortnight before it fell, chips were obferved to be dropping off from the joints of the archftones about ten feet on each fide of the middle, and alfo frorti another place on one fide of the arch, about twenty feet from its middle. The mafons in the neighbourhood prognolllcated its fpeedy downfal, and faid that it would feparatc in thofe places where the chips were breaking off. At length it fell ; but it firlt fplit in the middle, and about 15 or 16 feet on each fide, and alfo at the very fpringing of the arch. Immediately before the fall a fiiivering or crackling nolfe was heard, and a great man}' chips dropped down from the middle between the two places from whence they had dropped a fortnight before. The joints opened above at thofe new places above two inches, and in the middle of the arch the joints opened below, and in about five minutes after this the whole came down. Even this movement was plainly diitingulihable into two parts. The crown funk a little, and the haunches rofe very fenfibly, and in this (tate it hung for about half a minute. The arch (tones of the crown were hanging by their up- per corners. When thefe fplintered off, the whole fell down. We apprehend that the procedure of nature was fomewhat in this manner. Straight lines can be drawn within the arch-ftones from A (fig. i ;.) to B and D, and from thofe points to C and E. Each of the por- tions ED, DA, AB, EC, rcfid as if they were of one ftone, compofing a polygonal vault EDABC. When this is overloaded at A, A can defcend in no other way than by pufliing the angles B and D outwards, caufing the portions BC, DE, to turn round C and E. This motion mult raife the points B and D, and caufe the arch-ftones to prefs on each other at their inner joints i and r«' cient ; and the prefent condition of that noble briilge, mortar has let, but betore it has dried and acquired its which does not in any place ihow the fmalleft change utnioll hardnefs. Its bond is broken by this motion, of fliape, proves that he was not millaken. Looking and it is I'qneezed up, and never acquires its former on this work as the full, or at lead the fecond, fpeci- firmnefs. This is effeftually prevented by tlie preffure men of mafonic ingenuity that is to be feen in the exerted by the back of the invert, d arch, world, we imagine that our readers will be pleafcd with Above this counter arch is another niafs of courfed a particuUr account of its moll remarkable circura- rubble, and all is covered by a horizontal conrle of large j^3j,j,gj_ blocks of Portland ftone, buttuig againil the back of The fpan ha (fio-. i6.) of ihe middle arch is lOO the arch-ftone ZI and its correfponding one in the ad- feet, and its iieij;hrOV is 40, and the thickncfs KV joining arch. This courle conneds the feet of the two of the crown is lix feet feven inches. Its form is nearly arches, preferves the rubble-work irom too great com- 'j?iate'lll. elliptical; the part AVZ being an arch of a circle prcffion, and proteds it from u. ikiog water. Tl.is la(t whofe centre is C, and radius 56 feet, and the two la- circumltance is iniportant; for if the water which falls tcral portions A /■ B and Z a E being arches defcribed on the road- way is not carried iff in pipes, it foaks with a radius of ^ 5 feet nearly. The thicknels of the through the gravel or other rubbifh, rcfts on the mor- pier at rt * is 19" feet. The thicknefs of the arch in- tar, and keeps it continually wet and loft. It cannot creafes from the crown V to Y, where it is eight or efcape through the joints of g(/od n^afonry, and there- nine feet. All the arch-ftones have their joints direded fore fills up this part like a funnel, to the centres of their curvature. The joints are all Suppofing the adjoining arch fallen, and all tumbled 'jojTjrled, haviug a cubic foot of hard ftone let half way off that is not withheld by its fituation, there will ftiH into each. B)^this contrivance the joints cannot Aide, remain in the pier a mafs of about 3^02 tons. The nor can any weight laid on the crown ever b;eak the weight of the portion VY is about 2000 tons. The arch in that part, if the piers do not yield ; for a diredions of the thrults RY and YF are fuch, that it ftraight line from the middle of KV to the middle of would require a load of 4500 tons on VY to overturn the ioint YI is contained within the folid mafonry, and the pier round F. This exceeds VY by 2500 tons; a does not even come near the inner joints of the arch- weight incomparably greater than any that can ever be ftones. iherefore the whole rclifts like one (lone, and laid on it. can be broken only by cruthing it. The joint at Z is Such is the ingenious conftrudion of Mr Mylne. ft ■very nearly perpendicular to a line YF drawn to the evidently proceeds on the principles recommended outer edge of the foundation of the pier. By this it above ; principles which have occurred to his experience was intended to take off all tendency of the preffure on and fagacious mind during the courfe of his extenfive the joint rfZ to overfet the pier ; for if we fuppofe, ac- pradice. We have leen attempts by other engineers cording to the theory of equilibration, that this preffure to withftand the horizontal thrufts of the arch by- is neceffarily exerted perpendicularly to the joint, its means of counter arches inferted in the fame maimer diredion paffes through the fulcrum at F, round which as here, but extending much farther over the main arch; it is thought that the pier mull turn in the ad of over- but they did not appear to be well calculated for pro- fetting. This precaution was adopted in order to make ducing this effed. A comiter arch fpringing from any the arch quite independent of the adjoining arches ; lo point between Y and V has no tendency to hinder that that although any of them Ihould fall, this arch iliould point from rifing by the linking of the crown ; and run no riflt. {ach. a counter arch will not refill the precilely hori- Still farther to fecure the independence of the arch, zontal thruft fo well as the ftraight courfe of Mr iilylne. the following conftrudion was pradifed to unite it into _ _ _ . . .3* ' one mafs which ftiould rife altogether. All below the The great incorporation of architeds who built the 0"K'n o line fl^ is built of laro-e blocks of Portland ftone, dove- cathedrals of Europe departed entirely from the ftyles '", tailed with found oak. Four places in each courfe are of ancient Greece and Rome, and introduced another, interrupted by equal blocks of a hard ftone called Ken- in which arcades ijnade the prirtcipal part. Not finding /»/Z) rax, funk half way in each courfe. Thefe ad as in every place quarries from which blocks could be ioaeles breaking the courfes, and preventing them raifed in abundance of fuffic lent lize for forming the far- from Hiding laterally. projeding corniches of the Greek orders, they relin- The portion a Y of the arch is joggled like the up- quilhed thofe proportions, and adopted a ftyle of orna- nerpart. The interior part is filled up with large blocks ment which required no fuch projettions ; and having of Kentilh rag, forming a kind of courfed rubble-work, fubllituted arches for the horizontal architrave or li.itel, the courfes tending to the centres of the arch. The they were now able to ered buildings of vail extent under corner of each arch-ftone projeds over the one with fpacious openings, and all this with very fmall below it. By this form it takes fall hold of the rubble- pieces of ftone. The form which had been adopted for work behind it. Above this rubble there is conftrud- a Chriftian temple occafioned many interfedions of ed the inverted arch \ e G of Portland Hone. This arch vaultings, and multiplied the arches exceedingly. Con- fliares the preffure of the two adjoining arches, along ftant pradice gave opportunities of giving every pofliblc with the arch-ftones in Y a and in G b. Thus all tend variety of thefe interledions, and taught the art of ba- together to comprefs and keep down the rubble-work lancing arch againil arch in every variety of fituation. in the heart of this part of the pier. This is a very An art fo multifarious, and fo much out of the road ufeful precaution ; for it often happens, that when the of ordinary thought, cculd not but become an object centres of the arches are ftruck, before the piers are of fond ftudy to the architeds moll eminent for inge- nuity ARC [ nuity and invention. Becoming tluis the dupes of their own insfenuity, they were fond of difplaying it even when not neccflary. At lalt arches became their princi- pal ornament, and a wall or ceiling was not thought dreiT- ed out as it (hould be till filled full of mock arches, croffmg and butting on each other in every diredion. In this procefs in their ceilings they found that the pro- jefting mouldings, which we now call the Gothic trace- ry, formed the chief fupports of the roofs. The plane furfaces included between thofe ribs were commonly vaulted with very fnnall Hones, feldom exceeding fix or eight inches in thicknefs. This tracery therefore was not a random ornament. Every rib had a pofition and direftion that was not only proper, but even necelTarv. Habituated to this fcientific arrangement of the mould- ings, they did not deviate from it when they ornament- ed a fmooth furface with mock arches ; and in none of the highly ornamented ancient buildings will we find any falle pofitions. This is by no means the cafe in many of the modern imitations of Gothic architefturc, even by our bed architefts. Ignorant of the diredting principle, or not attending to it, in their ftucco work, they pleafe the unflondon weighs fcveral hundred tons, and is carried by a brick cone of eighteen inches tiiick, with perfetl fafety, as long as the bottom courfe is prevent- ed trom buriling outwards. The reafon is evident : The preffure on the top is propagated along the cone in the diredion of the flant ildc ; and, fo far from ha- ving any tendency to break it in any part, it tends ra. ther to prevent its being broken by any irregular prcf- lure from foreign caufes. „. For the fame reafons the odagonal pyramids, which Proper con- form the fpircs of Gothic architedurc, are abundantly '^''"'^"'" °^ firm, although very thin. The iides of the Ipire of^^^^^l] Sallfbury cathedral are not eight inches thick after the odagon is fully formed. It is proper, however, to di- D reft Arch. ARC [ 26 ] ARC rcA the joints to the axis of the pyramiil, a;id to make change, becaufi: the weight of eaoti courfe is fiiperaihled Ard •"""> the ctiuvfiiio- joints perpendicular to the flant fide, be- to that of the portion above it, to complete the prciTiire '^ caufe the projeifling moulding.; whicli run along the on the courfe belo\r. Through C draw the vertical angles are the abutments on which tlie whole pannel line BCG, meeting ", b, produced in C. We may take depends. A confiderable art is neceflary for fuppovting be to prefs the preffure of all that is above it, propa- thofe pannels or fides of the odlagon which fpriug from gated in this direftion to the joint KL. We may alio the angles of the fqnare tower. This is done by be- fuppofe the weight of the courfe HL united in I, and •'iiininiT a very narrow pointed arch on the fqnare tower ailing on the vertical. Let it be reprefented by b V, at a great .lillance below the top ; fo that the legs of If we form the panillclogram b FGC, the diagonal b G the arch bting very long, a ftvaight line may be drawn will reprefent the direftion and intenfity of the whole from the top of the keyilone of the arch through the preffure on the joint KL. Thus it appears that thi> wliolc archllones of the legs. By this difpofition the preffure is continually changing its ilircdion, and that thrufts arifipf from the weight of thefc four pannels arc the line, which will always coincide with it, m\ill be a made to meet on the maffive mafonry in the middle of curve concave downward. If this be precilely the the fides of the tower, at a great diftance below the curve of the dome, it will be an equilibrated vaulting ; fpringlniT of the fpire. This part, being loaded with but fo far from being the ftrongell form, it is the the "reat mafs of perpendicular wall, is fully able to weakeft, and it is the limit to an infinity of others, which ■withftand the horizontal thruft from the logs ot ihofe are all llrongcr than it. This will appear evident, it arches. In many fpires thefe thru.ls are ftill farther re- we fuppofe that b G does not coincide with the curve iifled by iron bars which crofs the tower, and are hook- A 3 B, but pail'es without it. As we luppole the arch- ed into pieces of brafs firmly bedded in the mafonry of Hones to be exceedingly thin from infide to outfule, it is, the fides. ^ plain that tliis dome cannot Hand, and that the weight ot Txarnplcs There is much nice balancing of this kind to be ob- the upper p.art will prefs it down, and fpring the vault- cf fuch con- ferved in the highly ornamented open fpires; fuch as ing outwards at the joint KL. But let us tuppofe, on ftrudtion. (i,ofg gf BrulFels, Mechlin, Antwerp, &c. We have the other hand, that b G falls within the curviliucal ele- not many of this fort in Britain. In thofe of great ment bTi. This evidently tends to pulh the arch-Hone magnitude, the judicious eye will difeover that parts, in.ward, towards the axis, and would caule it to llide in, which a common fpeftator would confider as mere or- fince the joints are fuppofed pcrfedlly fmooth and ilip- naments, are neceflary for completing the balance of the ping. But fince this takes place equally in every itone whole. Tall pinnacles, nay, even pillars carrying enta- of this courfe, they muil all abut on each other in the blatures and pinnacles, arc to be feen Handing on the vertical joints, fqueezing them firmly together. There- middle of the {lender leg of an arch. On examination, fore, refolving the thruft b G into two, one of which is we find that this is neceffary, to prevent the arch from perpendicular to the joint KL, and the other parallel to fpringintr upwards in that place by the preffure at the it, we fee that this lall thruH is witbilood by the verti- crown. The fteeple of the cathedral of Mechlin wasthe cal joints all around, and there remains only the thrufl moH elaborate piece of architcflure in this taHe in the in the direftion of the curve. Such a dome muH there- world, and was really a wonder ; but it was not calcu- fore be firmer than an equilibrated dome, and cannot lated to withHand a bombardment, which deHroyed it be fo eafily broken by overloading the upper part. jn I rng. When the curve is concave upwards, as in the lower Such frequent examples of irregular and whimfical part of the figure, the hue b C always falls below b B» buildings of this kind, fliow that great liberties may be and the point C below B. When the curve is concave taken with the principle of equilibration without riik, downwards, as in the Tipper part of the figure, 'b C if we take care to ficure the bafe from being tliruft paffcs above, or without b B. The curvature may be Butwards. This may always be done by hoops, which lo abrupt, that even b' G' fhall pafs without 'b B, and can be concealed in the mafonry ; whereas, in common the point G' is above B'. It is alfo evident that the arches, thefe ties would be vifible, and would offend the It is now time to attend to the principle of equili- brium, as it operates in a fimple circular dome, and to determine the thlcknefs of the vaulting when the curve is given, or the curve when the thlcknefs is given. Plate H. Therefore, let B 3 A (fig. 17.) be the curve which pro- •.Q duces the dome by revolving round the vertical axis .'il>. Srabihtyof We fhall fuppofe this curve to be drawn through the any elevation, however fmall ; nay, iince the fridion of a dome de- middle of all the arch- Hones, and that the courfing or two pieces of Hone is not iefs than half of their mutual vends on horizontal joints are every where perpendicular to the preffure, fuch a dome will Hand, although the tangent curve. We fhall fuppofe (as is always the cafe) that to the curve at the bottom (hould be horizontal, pro- the thlcknefs KL, HI, &c. of the arch-ftones is very vided that the horizontal thruH be double the weight fmall in comparifon with the dlmenfions of the arch, of the dome, which may eafily be the cafe if it do not If we confider any portion HA h of the dome, it is rife high. plain that it preffes on the courfe, of which HL is an Thus we fee that the ftabillty of a dome depends on Different arch-Hone, in a direftion bC perpendicular to the joint very different principles from that of a common arch, f''"™ '"*] HI, or in the direftion of the next fuperior element and is in general much greater. It differs alfo in ano-" ^ ""S A b oi the curve. As we proceed downwards, courfe af- ther very important circumHance, viz. that it may be ter eourfe, vye fee plainly ■ that this direflion mull open in the middle : for tha uppermoll courfe, by tend- tjig |iriiiciples force which thus binds the Hones of a horizontal courlu together, by puHiing them towards the axis, will be greater in flat domes than in thofe that are more con- vex ; that it will be Hill greater in a cone ; and greater Hill in a curve whofe convexity is turned inwards : tor in this lall cafe the line b G will devi.ite moH remark- ably from the curve. Such a dome will Hand (having polifhed joints) if the curve fprings from the bafe with Ai-clv ARC [27 ing eqmlly in every part to flicic in toward flic axis, /) ' proires all topfether in tiie vertical joints, and acts on the next covirfe like the key ftone of a common arch. Thcrefi-'rc an arch of equilibration, which is the weak- eft of all, mar be open in the middle, and carry at top another building-, fnch as a lanthern, if its weiglit ^o rot exceed that of the circular feg^ment of the dome that IS omitted. A greater load than this would indeed break the dome, by canling it to fpring up in fome of the lower courfes ; but this load may be increafed if the curve is flatter than the curve of equilibration : and any load whatever, which will not crufli the ilones to powder, may be fet on a truncate cone, or on a dome formed by a curve that is convex toward the axis; pro- vided always that the foundation be effeftually prevent- ed from living out, cither by a hoop, or by a fufiicient mafs of folid pier on wliich it is fet. We have mention- ed the many failures which happened to the dome of St Sophia in Conilanlijiople. We imagine that the thru It of the great dome, bending the eallern arch out- ward as foon as the pier began to yield, dcllroyed the half dome which was leaning on it, and thus, almolt in an inllant, took aWay the eallern abutment. We think that this might have been prevented without any change ] ARC and complete the parallelogram MONP, and draw ArA. OQjierpendicular lo the axis, and produce b¥, cutting '■""V" the ordinates I'n E and e. It is plain that MN is to MO as the weight of the arch HA^ to the thrntl ic which it exerts on the joint KL (this thruft being pro- pagated through the coiirfe HILK) ; and that MQ_, or Its equal ie, or ^ i/, may reprefcnt the weiffht of the halfAIi^ Let AD be called .v, and DB be called jr. Then ie == X, and eC =: y (bccaiife l/c is in the direftion of the element pi)- It is alio plain, that if we make y conflant, BC is the fecond fluxion of x, or BC = x, and ie and BE may be conlidered as equal, and taken indifcriminately for .v. We have alfo i5C = V x- + jr*. Let cJ be the depth or thicknefs HI of the arch-ftoues. Then (/ V .V -f- j'= will reprefent the traoe/liim HT^: and lince the circumference of each cmirfe incrj.tles in the proportion of the radius _)■, dy V x^ -)- j/^ will ex. prefs the whole courfe. If y be taken tc leprcfent the fum or aggregate of the quantities anuexec' to it, the formula will be analogous to the fluent of a .luxion, and 41 !.".-A^''T'i'_^'.?."! pJ1"A;-L'u1 t"'L'^''i^l';"„''"°?u^ //j-v/^^-l-/ win reprefent the whole r.ai>, and alfo the weight of the vaulting down to the joint HI. Theref ore we have this proportion y^t/j Vx»-|.y : Jy \/x^ +f=:ie:iF,=i(: C G, - ^d : CG, d y X v x' -I- _jr» with iron, as was praft'led by Mitliael Angelo in the vaiHy more ponderous dome of St Peter's at Rome, and by Sir Chrillophcr Wren in the cone and the inner [cellency dome of St Paul's at I^ondon. The weight of the lat- rhedomet;.r conliderably exceeds 3000 tons, and they occalion ■'''" a horizontal thrull which is nearly half this quantity, the elevation of the cone being about 60". This be- ' ing diilributed round the circumference, occalions a ftrain on the hoop = - — of the thruft, or nearly 23S tons. A fquare inch of the worft iron, if well forged, will carry 2; tons with perfeft fafety ; therefore a hoop of 7 inches broad and T^- inches thick will com- pletely fecure this circle from burfting outwards. It is, however, much moi-e completely fecured ; for befides a hoop at the bafe of very nearly thefe dimenfions, there are hoops in different courfes of the cone which bind it into one mafs, and caufe it to prefs on the piers in a di- reftion exadlly vertical. The only thrults v/hich the piers fuftain are thofe from the arches of the body of the church and the tranfepts. Thefe are moft judi- cioufly directed to the entering angles of the building, and are there refifted with infuperable force by the whole lengths of the walls, and by four folid mafles of mafon- ry in the corners. Whoever confiders with attention and judgment the plan of this cathedral, will fee that the thrulls of thefe arches, and of the dome, are incom- parably better balanced than in St Peter's church at Rome. But to return from this fort of digreffion. .eiiry of We have feen that if 3G, the thruft compounded of ; curves the thruft i C, exerted by all the courfes above HILK, aper f»r and if the force b F, or the weight of that courfe, be mes. everywhere coincident with b B, the element of the curve, we ftiall have an equilibrated dome ; if it falls within it, we have a dome which will bear a greater load ; and if it falls without it, the dome will break at the joint. We muft endeavour to get analytical expref- fions of thefe conditions. Therefore draw the ordinates ■tH", BDB'', Cr/C". Let the tangents at 6 and 3" meet the axis in M, and make MO, MP, each equal to = X : CG. Therefore CG /'^^K^'> + j),i If the curvature of the dome be precifely fuch as puts it in equilibrium, but without any mutual picfTure in the vertical joints, this value of OG muft be equal to CB, or to X, the point G coinciding with B. This condition will be exprefTedbythe equation — — "- •' J d y \/ x^ -f-j" =r X, or, more conveniently, by I dy v/k^ + J^ * But this form gives only a tottering equilibrium, inde- pendent of the frittion of the joints and the cohefion of the cement. An equilibrium, accompanied by fome firrft liability, produced by the mutual preffure of the verti- cal joints, may be exprefled by the formula . / " - X , dytJ x^ ■{■ y^ X , t , . , ■:P'-r, or by —.=.^^,=r=z= .^-f , where t is fome Jdy^x^+y^ X * variable pofitive quantity, which incrcafes when x iu- creafes. This laft equation will alfo exprefs the equi- librated dome, if / be a conftant quantity, becaufe irt this cafe — is =± 0. t Since a firm ftability requires that — — — "*"-•< f^y V^^' + y'' (hall be greater than .v, and CG muft be greater than CB ; Hence we learn, that figures of too great curvature, whofe fides defcend too rapidly, are improper. Alfo, 1> a fincc Arch. ARC fince (lability requires that we have [ 2S 1 A R tly'x V X' +y' greater than y^/jr V \'+ >■". we learn that the upper part of the dome mud not be made very heavy. This, by dimiiiifhing the proportion of A F to ^ C, diminifties the angle c I' G, and may fet the point G above B, which vill infallibly fpring the dome in that place. We fee here alfo, that the alj^^cbraic analyfis expreflcs that peculiarity of dome-vaulting, tliat the weight of the up- per part may even be fupprcded. The fluent of the equation dy y/jc- + y' __ x , _^ Jdy >y 7F+f x^ ' is moft eafily found. ItisL/(/j v/«' + ji- = L x + L. t, where L is the hyperbolic logarithm of the quan- tity annexed to it. If we confider y as conftant, and corred the fluent fo as to make it nothing at the vertex, it may be cxprefTcJ thus, "LJ J y v «'+.V' — La=Lx T • ■ T -r-L- • T /"'iV *"+J — L.y -f Jl. /. 1 his gives us Ly =— -^ Jdy v/£+7 and therefore/— a y This laft equation will eafily give us the depth of vaulting, or thicknefs d of the arch, when the curve is dome, whofe outline io an undulated curve, may be made abundantly firm, elpecially if the upper pait be convex and the lower concave outwards. The chief difficulty in the cafe of this analyfis arifes from the neceffity of exprefling the weight of the in- ciKrbent pait, nx J dyV^^ + j'- This requires the meafurL-mcnt of the conoidal lurfacc, which, in moil cafes, can be had only by approximation by means of infinite feriefes. We cannot expecl that the generality of practical builders are familiar with this branch of ina- thematics, and therefore will not engage in it here; but content ourfelves with giving fuch inllances as can be undcrftood by fuch as have that moderate mathematical knowledge v/hicli every man fhould poflefs wlio takes the name of engineer. The furface of any circular portion of a fphere Is ve- rv eafily had, being equal to the circle defcribed'with a radius equal to the chord of half the arch. This radius is evidently := v "■^ "^ y^- In order to difcover what portion of a hemifphere may be employed (for it is evident that we cannot em- ploy the whole) when the thicknefs of the vaulting is uniform, we may recur to tlie equation or formula dy X s^f x' — y- —fdy v/«^ -fj),\ Let a be the radius g iven. For its fluxion is _Z a t X ■\- at X nd j£_+_f fdy ^/x^ + f- will then be greater than x. This will give or 0,786, and the height will l-t 618. The arch from the vertex is about 31° 49'. Much more of the hemifphere cannot itand, even though aided by the cement, and by the friftion of the courfing joints. This laft circumftance, by giving connedtion to the upper parts, caufes the whole to prefs more vertically on the courfe below, and thus diminifhes the outward thruft ; but it at the fame tiine diminifties the mutual abutment of the vertical joints, which is a great caufe of firmnefs in the vault- ing. A Gothic dome, of which the upper part is a portion of a fphere not exceeding 45° from the vertex, and the lower part is concave outwards, will be very ilrong, and not ungraceful. But the public tafte has long rejefted this form, and Dome" oF feeins rather to feleA more elevated domes than this por-St Peter i tion of a fphere; becaufe a dome, when feen from a*' ""' fmall diftance, always appears flatter than it really is. The dome of St Peter's is nearly an ellipfoid externally, of which the longer axis is perpendicular to the horizon. It is very ingenioufiy conftruded. It fprings from the bafe perpendicularly, and is very thick in this part. After rifing about 50 feet, the vaulting feparates into two thin vaultings, which gradually feparate from each other. Thefe two ftiells are connettcd together by thin partitions, which are very ai-tincially dovetailed in both, and thus form a covering which is extremely ftiff^ while it is very light. Its great ftiff'nefs was neceffary for en- abling the crown of the dome to carry the elegant ftoac lanthern 43 *ri.1i. ARC [ 2 lantliern with fafcty. It is a wonderful performance, '~r—' and has not its equal in the world ; but it is an cnor- irious load in coiiiparifon with the dome of St Paul's, and th'S even indci)endent of the difference of fize. If they were of equal dinienfiDns, it would be at leall five times as heavy, iiiiJ is not fo firm by its gravity ; but as it is connefted in every part by iron bars (lodged in the folid niafonry, and well fecured from the weather by having lead melted all round them), it bids lair to lall for ages, if the foundations do not fail. If a circle be deferibed round a centre placed any- 'Jatcir. where in the tranfverle axis AC (fig. l8. N' i.) of an ellipfe, fo as to touch the ellipfe in the extremities B, b, of an ordinate, it will touch it internally, and the circu- lar arch V>ab will be wholly within the eUiptical arch 13 A b. Therefore, if an elliptical and a fpherical vault- ing fpring from the fame bafe, at the fame angle with the horizon, the fpherical vaulting will be withia the elliptical, will be flatter and lighter, and therefore the weight of the next courfe below will bear a greater pro- portion to tiie thruil in the direiSion of the curve ; therefore the fpherical vaulting will have more liability. On the contrary, and for fuiiilar reafons, an oblate el- liptical vaulting is preferable to a fpherical vaulting fpringing with the fame inclination to the horizon. (Fig. i8. N°2.). menfions Perfuaded, that what has been faid on the fubjeft belt convinces the reader that a vaulting perfeitly equilibra- „j_ ted throughout is by no means the betl form, provided that the bafe is fecured from feparatiiig, we think it un- neceffary to give the inveftigation of that form, which lias a coufiderable intricacy ; and (hall content ourftlves with merely giving its dimenfions. The thicknefs is fappofcd uniform. The numbers in the tirlt column of the table exprefs the portion of the axis counted from the vertex, and thofe of the fecond column are the lengths of the ordinates. 4* 44 AD DB AD DB AD DB 0,4 100 610,4 1080 2990 ( j6o .^+ 200 744 1 140 ' 3442 16:0 11,4 300 904 1200 3972 1640 26,6 4C0 I 100 1260 4432 1670 y2.4 500 '.iS^ .320 4952 1700 9''+ 6co 1 j22 1360 Sii^' 1720 146,8 ■700 1738 14CO 51S6 1740 2i^.4 8oo 1984 1440 62 14 1760 326,6 900 2270 1480 6714 1780 465,4 ICOO 2602 1520 7260 1800 The curve delineated in fig. 19. is formed according to thefe dimeufions, and appears dellitute of graceful- nefs ; becaufe its curvature changes abruptly at a little diftance from the vertex, fo that it has fome appearance of being made up of different curves pieced together. But it the middle be occupied by a lanthern of equal, or of fmaller weight, this defeft will ceafe, and the whole will be elegant, nearly refembling the exterior dome of St Paul's in Loudon, anta^es. It is not a fmall advantage of dome-vaulting that it -me- is lighter than any that can cover the fame area. If, ""S- moreover, it be fpherical, it will admit coufiderable va- rieties of figure, by combining different fpheres. Thus, a dome may begin from its bafe as a portion of a large 9 ] ARC liemifphere, and mny be broken off at any horizontal .Arch, courfe, and then a limilar or a greater portion of a fmal- v— ~ ler fphere may fpring from this courfe as a bafe. It alfo bears being inttrfedU'd by cylindrical vaultings in every direftion, and the interfedtions are exart circles, and always have a plealing effedt. It alfo fprings moll gracefully from the heads of fmall piers, or from the corners of rooms of any polygonal Ihape ; and the arches formed by its interfcdtions with the walls are always cir- cular and graceful, forming very handfome fpandrels in every pofition. For thefe reafons Sir Chrillopiier Wren employed it in all his vaultings, and he has exhibited many beautiful varieties in the tranfepts and the aiiles of St Paul's, which are highly worthy of the obferva- tion of architefts. Nothing can be more graceful than the vaultings at the ends of the north and fouth tran- fepts, efpecially as finilhed off in the fine infide view , publiflied by Gwynn and Wale. .^ We conclude this article with obferving, that theEflTeflsof conneftion of the parts, arifing from cement and from ".ll?"' ?'''^ friction, has a great effedt^on dome-vaulting. In the fii(»i;,ii d(HTt€vaulc- fame way as in common arclies and cylindrical vaulting, ire, it enables an overload on one place to break the dome in a diftant place. But the refiftance to this efiett is . much greater in dome-vaulting, becaufe it operates all round the overloaded part. Hence it happens that domes are much Icfs Ihattered by partial violence, fuch as the falling of a bomb or the like. Large holes may be bro- ken in them without much affedfing the rell ; but, on the other hand, it greatly diminillus the flrength which fiiould be derived from the mutual preffure in the verti- cal joints. Fridtion prevents the Aiding in of the arch Hones which produces this mutual prtflure in the verti- cal joints, except in the very lilglietl courfes, and even there It greatly diminilhes it. Thefe caufcs make a great change in the form which gives the greatell itrength ; and as their laws of adlion are but very im- perfectly underftood as yet, it is perhaps impoffible, in the prcfent If ate of our knowledge, to determine this form with tolerable precifion. We fee plainly, how. ever, that It allows a greater deviation from the bell form than the other kind of vaulting, and domes may be made to rife perpendicular to the horizon at the bafe, although of no great thicknefs; a thin^ wiiicli mult nut be attempted in a plane arch. The mimeide addition of flrength which may be derived from lioop- "ig, largely compenfates tor all defedts ; and there is hardly any bounds to the extent to which a very thia dome-vaulting may be carried, when it is hooped or framed in the directimi of the horizontal cou -fes. The roof of the Halle du Bled at Paris is but a foot thick, and its diameter is. more than 200, yet it appears to have abundant flrength. It is, on the whole, a noble fpecimen of architcdture. We mufl not conclude this article without taking rhelfm notice of that magiuTicent and elegant arch whichh.tibiclye.it. been eredted in call iron at WerciDouth, near Sunder; SunrterlanJ. land, in the county of Dm-ham. The inventor and ar. '^•'"''^'*'* chitedt is RoVv'L.iND Burdon, Efq; one of the repre. fentatives of that county in the prefeut Parliament. This arch is a fegment of g circle whofe diameter is about 444 feet. The fpan or cord of the arch is 236 feet, and its verfed fine or fpring is 34 feet. It fpring? at the elevation cf 60 feet from the furface of the ri. ARC [3: Arch. Ter at low water, fo that vefTcls of 200 or pcrhnp'; 300 ' ■ V ' ' tons blinieQ may pafs under it in tlio middle of the Ilrcam, and even 50 feet on each fide of it. The fweep of the arch confiih of a feries of frames of caft iron, which butt on each ether, in the fame man- ner as the voufToirs of a ilone arch. One of thefe frames or blocks (as we (hall call them in future) is re- Plate IV. prcfentcd in fig. 1. as feen in front. It is caft in one piece; and confifts of three pieces or arms BC, BC, BC, the middle one of which is two feet long, the upper be- in.g fomewhat more, and the lower fomewhat Icfs, be- caufe their extremities are bounded by the radius drawn from the centre of the arch. Thefe arms are four inches fquarc, and are connefted by other pieces KL, of fuch length that the whole length of the block is five feet in the dirtftion of the radius. Each arm has a flat groove on each fide, which is expreffed by the darker fhading, three inches broad and ihree-foniths of an inch deep. A feAion of this block, through the middle of KL, is reprefented by the light-fliaded part BBB, in which the grooves are more diftindly perceived. Thefe grooves are intended for receiving flat bars of malleable iron, ^viiich are employed for connefting the different blocks with each other. Fig. 2 repvelents two blocks united in this manner. For this purpofe each arm has two fquare bolt-holes. The ends of the arms being nicely trimmed off, fo that the three ends butt equally clofe on the ends of the next bloc4c ; and the bars of ham- itiered iron being alfo nicely fitted to their groove,", fo as to fill them completely, and have their bolt holes ex- adlly correfponding to tliofc in the blocks, they are put together in fuch a manner that the joints or meetings of the malleable bars may fall on the middle between the bolt-holes in the arms. Flat headed bolts of wrought iron are then put through, and keys or forelocks are driven thro' the bok-tails, and thus all is firmly wedged together, binding each arm between two bars of wrought iron. Thefe bars are of fuch length as to conned feve- ral blocks. '' In this manner a feries of about 125 blocks are joined together, fo as to form the precife curve that is in- tended. This feries may be called a rib, and it (lands in a vertical plane- The arch confifts of fix of thefe ribs, diftant from each other five feet. Thefe ribs are connefted together fo as to form an arch of 32 feet in breadth, in the following manner: Fig. 3. reprefei^s one of the bridles or crofs pieces which conned the difl'erent ribs, as it appears when viewed from below. It is a hollow pipe of caft iron, four inches in diameter, and has at each end two pro- jefting fhoulders, pierced with a bolt-hole near their ex- tremities, fo that the diftance between the bolt-holes in the fhoulders of one end is equal to the diftance between the holes in the arms of the blocks, or the holes in the wrought iron bars. In tlie middle of the upper and of the under fide of each end may be obferved a fquare pro- minence, more lightly (haded than the reft. Thefe pro- jeftions alfo advance a little beyond the flat of the ft^ioul- ders, forming between them a {h:i'.low notch, about an inch deep, which receives the iron of the arms, where they butt on each other, and tlius gives an additional ' firmnefs to the joint. The manner in which the arms are thus grafped by thefe notches in the bridles is more diftinftly feen in fig. 2. at the letter H in the middle of the upper rail. 1 ARC The rib having been all trimmed and put tonrethei', Arc} fo as to form the exaft curve, the bolts are ail taken *"~— v— ' out, and the horizontal bridles are then fet on in their places, and the bolts are again put in and made fall by the forelocks. The bolts now pafs through the fhoul- ders of the bridles, through the wrought iron bars, and through the cafl iron arm that is between them, and the forelocks bind all faft together. The manner in which this conneftion is completed is dillindtly feen in fig. 2. which fhews in perfpedlive a double block in front, and a fingle block behind it. The butting joints of the two front blocks are at the letters E, E, E ; the holes in the fhoulders of the horizontal crofs pieces arc ^'^■. ... 4! This conflrudion is beautifully fimple and very judi- its con- cious. A vaft addition of ftrength and of ftiffnefn isHrudiot procured by lodging the wrought iron bars in grooves. 'jP'.^ * formed in the caft iron rails; and for this purpofe itisof^'^ '"°'" great importance to make the wrought iron bars fill the grooves completely, and even to be fo tight as to re- quire the force ot the forelocks to draw them home to the bottom of the grooves. There can be no doubt but that this aich is able to witlifland an enormous pref- fiire, as long, as the abutments from which it fprings do not yield. Of this there is hardly any rifle, becaufe they are maffes of rock, faced with about four or five yards (In fome places only) of folid block mafonry. The mutual thrufts of the frames are all in the direftlon of the rails, fo that no part bears any tranfverfe tlrain. We can hardly conceive any force that can overcome the ftrength of thofe arms by prcffure or crufhing them. The manner in whiv.'h the frames are connected into one rib, effedlually fecures the butting joints from flipping; ^nd the accuracy with which the whole can be execu- ted, fecures us againft any warping or deviation of a rib from the vertical plane. But when we confider the prodigious fpan of thii arch, and refledl that it is only five feet thick, it fliould feem that the moll perfed equilibration Is indifpeiiiably neceffary. It Ij but like a film, and muft be fo fupple that an overload on any part mull have a great ten- dency to bend it, and to caufe it to rife in a diftant part ; and this eficft is increaled by the very firm- nefs with which the whole flicks together. Tiie over- loaded part afts on a diftant part, tending to break it with all the energy of a long lever. This can be prevented only by means of the ftifinefs of the diftant part. It Is very true, the arch cannot break in the ex- trados except by tearing afunder the wrought iron bars which conneft the blocks along the upper rail, and each of thefe requires more than a hundred tons to tear It afunder ; yet an overload of five tons on any rib at its middle will produce this flrain at twenty feet from the fides, fuppofing the fides held firm in their pofitlon. It were defirable therefore that fomething were done to fliffen the arch at the fides, by the manner of filling up the fpandrels, or fpace between the arch and the road- way. This Is filled up In a manner that is extremely Thougli light and pleafing to the eye, namely, by large cafl Iron"ne par circles, which touch the extrados of the arch and touch!"" '' ' the road-way. The road-way refts on them as on ^oytivsol' many hoops, while they reft on the back of the arch, ^rovem :• and alfo touch each other laterally. We cannot think that this contributes to the ftrength of the arch ; for thefe hoops will be eafily comprefTed at the points of contaft, . 4? PT>ATE L. I'l.ATK ir n.ATK TTI lULlXillC AXHI^rG-^'^ iM.ATR ^^■. 5 ARC r 3P ] ^ ^. ^ . •eh, contaft, afiJ, changing their fhape, will oppofe very ignorant and barbaro.is ?" This qiieftion has occupietl Archltec- litec- lijtig refiltance. We think that this part of the arch the attention of many ingenious men, who have attri- j might have been greatly (liffencd and ftrengthened, by bn'ed the Gothic ftjle of building, fome to neceffity, connefting it with the road-way by trufled frames, in and others to an imitation of the works ot nature. That, the fame way that a judicious carpenter would have fra- where materials are bad, l.irger edihces can be ereitcd med a roof. If a ftrong call iron pillar had been made in the Gothic than in the Grecian llyle, has been made to reft on the arch at about 20 feet from the inipolt, fiifficiently evident in the articles to which we have re- and been placed in the direftion of a radius, the top of ferred ; and that necefilty is tlie parent of invention, is this pillar might have been connefted by a di.igonal bar an adage which has been too long received to be now of wrought iron with the impoil of the aich, and with called in qneilion. But whence came the peculiarities the crown of the arch by another (tring or bar of the of the Gothic ornaments in building, the pointed arch,_ ' fame materials. Thefe two ties wo\dd canfe the radial and the double row of clullered pillars compofed of pillar to prefs ilrongly on the back of the arch, and flender iliafts, which, reaching from the ground almoll they mull be torn afunder before it cjuld bend in that to the roof of the building, are there Iprcad out in place in the fnialleft degree. Suppofing them of the all dircftions, forming the ribs or groins of a vaulted fame dinienfions as the bars in the arms, their pofition roof? would give them near ten times the force for refilling the The mod fatlsfaftory folutlon of this queftion which ftrain produced by an overload on the crown. we have feen, is in a memoir publiilied in the fourth vo- This beautiful arch contains only 260 tons of iron, lume of the Tranfattions of the Royal Society of lidin- of which about 51; are wrought iron. The fuperftruc- burgh, by Sir James Hall, Bart, with whole pcrmif- ture is of wood, planked over a-top. This lloor is co- lion the following abllraft is laid before our readers, vered with a coating of chalk and tar, on which is laid " Although the connedion between beauty and the materials for the carriage road, coniilling of marie, utility be Hill involved in fuch obfcurity, that we are lime (lone, and gravel, with fnot-ways of flag ftones at unable to decide concerning the univerfality of that the fides. The weight of the whole did not exceed a connedion, of one thing we are certain, that, in a thoufand tons ; whereas the lighteft Hone arch wiiich work intended to anfwer fome ufeful purpofe, what- could have been ercdled would have weighed fifteen ever vilibly counteradts that purpofe always occafions thoufand. It was turned on a very light but llifF leaf- deformity. Hence it is, that, even where ornament folding, moft judicioufly conftrncted for the prefervatiou is principally intended, the oilenlibly ufeful objeA o£, of its form, and for allowing an uninterrupted paflage the work, if it have any fuch, muft be provided for^ for the numerous fhijjs and fmall craft which frequent in the firft place, in preference to evi;ry other conllder- the bufy harbour of Sunderland. The mode of framing at ion. the arch was fo fimple and eafy, that it was put up in, " But in moft ufeful works, fome parts occur, the ten days! without an accident ; and when all was ft- fhape of which is quite indifferent witli refpeft to the nilhed, and the fcaffolding removed, the srch did not propofcd utility, and which, therefore, the artifl is at lenfibly change its form. The whole work was execu- liberty to execute as he pleafcs : a liberty which has ted in three years, and coR about L. 26,000. opened a wide field to the taite and invention of inge- ARCHI i'ECTURE is an art of fo much import- nious men of every age and country, who have turned ance, and capable of fo many embellilhmcnts, as to their attention to the compofition of ornaments; and have employed the attention and talents of men of whofe exertions have been more or lefs influenced by icience in almoft every age, and in every country, the (late of civilization in which they lived. It would. It is generally thought to have been carried to the feem, however, if we may judge by thofe various ef- utmoll perfeition among the Greeks and Romans ; forts, that little has been elfedted I>y mere human in- and it has been the aim of the moft eminent architects genuity ; fince we fee that recourfe h;is been had, al- «f modern times to imitate with fidelity the buildings of moll univerfally, to nature, the great and legitimate thofe accomplilbed nations. There is, however, another fource of beauty ; and that ornament has been attain- fpecies of architefture, which was introduced into Eu- ed by the imitation of objeds, to which flic has given rope in the middle ages, and is of fuch a nature as to a determinate and charaderillic form, ilrike every unprejudiced obfcrver with admiration and " Where the materials employed are themfelves pof. afloniftimeiit. The architednre to which wc allude feffed of variety and elegance, the attainment of this ob- has been called, perhaps with little propriety, jcd requires little or no alteration of their natural forms. Gothic ylRCHiTEcrvRS. It is that wiiich is to be view- Thus cups are made of fliells, of cocoa-nuts, orof ollrich ed in all our ancient cathedrals, and in other large build- eggs ; the charader and beauty of which depend upon, ings which have been ereded from the middle of the the natural form of the materials: and in the cafe of 1 2th to the beginning of the i6th centui-y. That fuch the bottles ufed by the Roman Catholic pilgrams, an edifices have been conftruded on principles of fcience, example occurs of an utenfil, in which the natural form has been fhewn elfewhere (fee Roof, Encycl. and Arch, has undergone little or no variation, fince it confifts of in this Suppl.) : but a queftion ftill prefcnts itfelf to the the hard- outward fkin of a gourd, of the fame fhape in inquilitive mind, " How came fuch ftrudures to be which it grew upon the plant (a). This laft clafs of. thought of by a people whom we are accuftoraed to call forms has been introduced, by imitation, into works compofed (a) " Even in this cafe, however, the natural form undergoes a certain degree of modification, by the device employed to produce the neck of the bottle. The fruit, while fmall and tender, Is furrounded with a llring, which remaining during its growth, prevents the part, thus bound, from fwelling with the reft.." ARC [ 32 ] ARC Arclu'ec- compofed of rtiapelefs niaterlals. Tims we have iilver equal to tliat between the rows, and each pod being Aidiltee. "" ""■ cups in the form of thofc made of (liells, and fruitdiflies railed above the ground to a height equal to tliree of t^^e- * of ftoneware in the form of baflcets. thofc intervals ; then a let of long and flexible rods of v— "* " As ilone is not naturally potTcfTcd of any peculiar willow being applied to each poll, let them be thiull fliape, and as the ufel'ul objeift propoled, by llrudfures into the ground at its bafe, and bound to it by two formed of it, may be accomplilhed in various ways, tyiugs, one near the ground, and another at two-thirds very great latitude is left to the invention of the artift. of its heiglit ; the rods being left loofe from this laft We ke, accordingly, that in every country where much point upwards, and free to be moved in any diredtion. rciinement has been introduced, great pains have been Let three rods be connc6ted with each fiutlide i-orner bellowed in ofiiamenting Hone buildings with figures poll, and five with each of the others, and Itt their po- reprcfenting various natural objefts ; whilll the build fition be fuch as to cover tlie infide of the pull, fo tiiat ing itfelf has been executed in imitation of a llrufture, when feen from between the rows the lower part of compofed of materials which naturally poflefs a deter- each poll fhall be concealed from the view, and prefcnt ninate and charafterlllic form. Such was the method the appearance of a bundle of rods (fig i.) Plate V, followed by the architefts of ancient Greece, who con- Things being thus difpofed, the flceleton of a thatch- llruSed temples, and other public edifices, in imitation ed roof may be formed by means of the ioofe ends of of a iniflic fabric, compofed of fquare beams, fupported the rods. A rod from one of the polls being fo bent upon round polls or llems of trees, and who derived the as to meet a fimilar one from, the poll immediately op- numerous ornaments of that beautiful llyle from circum- polite to it, in the middle of the fpace between them, fiances which would naturally take place in fuch a ftruc- let the two rods be made to crofs each other, and let ture. them be bound together at their crofling (tig. 2.), and " A faint and dillant refcmblance, however, of the we fliall have the exadl form of the Gothic arch The oriT-inal, has generally been found to anfwer all the end fame being done with each pair of oppofite polls, and a propofed by the imitation ; a refemblancc, which may fet of pointed arches being formed, let them be conneft- ionietlmes be traced in the general diftribution of the ed together by means of a llraight pole laid upon the edifice, fometimes in its minute parts, and not unfie- forks of the crofling rods, and bound to each of them, qucntlv in both. as in fig. 3 : then let a Ioofe rod be brought from eacti " But the forms of nature thus introduced have been of any two contiguous polls in the fame row, fo as to rreatly modified by thofe of mafonrv. For though form a pointed arch, fimilar to that juft defcribed, and ilone is by nature fliapelefs, yet, in the courfe of prac- nearly of the fame height. This being done with every tice, many peculiar forms have been long ellablilhed, two contiguous polls (fig. 4), and a new fet of pointed and currently employed, in working it ; fuch as flraight arches being thus produced. Handing oppoiite to each, lines, plain furfaces, fquare angles, and various mould- other in pairs, let each pair be bound by a horizontal ings ufed to foften the cffedl of abrupt terminations : pole lying on the oppofite forks, and crofling the Ion- all of which, originating in motives of mechanical con- gitudinal pole defcribed above. venience, and of fimplc ornament, had, in very early " Two of the rods of each corner poll, and three of times, been appropriated to mafonry, and conlidered as thofe of each of the others, being thus dilpofed of, we eflential in every finiflied work of ftone ; fo that, when have one of each corner poft and two of each middle' the imitation of nature was introduced, thefe mafonic poll Hill to employ, which is done as follows: A pair of forms Hill maintained their ground, and, being blended thefe unoccupied rods being brought from any two polls Tvith the forms of nature, the two clalfeS reciprocally which Hand diagonally to each other, and made to meet modified each other. in the middle, not as in the firll cafe crofling in aa " This combination of art with nature, of which we angle, but fide by fide, forming a femicircle, and join- fee the moll perfedl example in the Corinthian capital, ed together after the manner of a hoop ; and the fame produces what are called architeftonic forms, in which being done with every pair of diagonal polls (fig. 5.), the variety of nature, being fubjefted to the regularity the whole rods will have been employed. of art, the work acquires that peculiar charafter which, " In this manner a frame would be conltrufled fit to in a ijatural objedl, we confider as offenfive, under the fupport thatch or other covering; and fuch a one has nsmt o{ formu/i/y ; but which, in architecture, we ad- probably been often ufed. It would fcem, however, mire as a beauty, under the name of fymmetry : thus, that, for the fake of llrength, the number of rods has we reprobate the formality of an avenue, and praife the been increafed in each duller, by the introduflion, be- fymiretry of a colonnade. tween every two of tiiem, of an additional rod, which " Such is the nature of architeftonic imitation ; a rifing with them to the roof, ilill continues its middle .(device which probably originated in accident, but to pofition, as they fpread alunder, and meets the horizon- whi(,h architefture is indebted for its higheft attain- tal pole at an intermediate point. This is (liown in ments." " f'g- 6. which is drawn with its covering of thatch ; and. As the ftone edifices of ancient Greece were con- from the imitation of a dwelling fo conllrufted, we may ilrufted in imitation of a wooden fabric, compofed of eafily trace the three leading charafteriftics of Gothic fquare beams laid at right angles on round pofts or architefture, the pointed arch, the cluftercd column, ftems of trees, Sir James conceives that the Gothic fa- and the branching roof, as exhibited in fig- 7." hrics with pointed arches have been executed in imita- Upon the fame principles Sir James Hall, with much tion of a rullic dwelling, conftrufted in the following ingenuity, accounts for the peculiar forms of the Go- manner : Suppofe a fet of round pofts driven firmly in- thic door, the Gothic window, and the pointed fpire : to the ground in two oppofite rows, the interval be- but it is not our intention to fuperlede the neceflity of tween the neighbouring polls in the fame row being having recourfe to his memoir, but to excite the defire of Rgl lo- 2 n Fig.,? Fi^4. I Irchitec- lure II . .rithmctic, A R I [ 33 ] ART of our readers to perufe as well that paper as a larger metic, however, or togjjlic , lias been ufed by Vieta and Arithmetic work which he promifes on the fame fubjcft, and in others for the rules of computations in aigebia. " .. ■ ■ ■ ' ' . . .1 _ -11 .-J 1 .u -.._.-:_ Political ARifUMETic. See Political Aruhmetic, « Encycl. Sexagefimal Arithmetic. See Arithmetic (HiJI.) Encycl. TetraSic Arithmstic, is that in which only the fo'jr charafters O, F, 2, 3, are ufed. A treatifc of this kind of arithmetic is extant by Erhard or Echard Weigel. which we doubt not but they will find both entertain ment and inftruftion. We (hall conclude this article, therefore, with an experimental proof of the juftnefs of his hypothefis. In the greater part of our late attempts at Gothic architetlure, it is allowed by every man of tafte that we have failed. The failure is to be accounted for by the buildings having been conftrudled upon no confiftent But both this and binary arithmetic are little better principle, applicable to every part of them, but upon a than curiofities, efpecially wiiii regard to praftice ; as fervile copying of ancient edifices, of which the llruc- all numbers are much more compendioufly and conve- ture was little underftood by the copiers. Sir James Hall, niently exprefled by the common decuple fcale. however, by applying his theory to practice, has con- Univerfal .-^kithmstic, is the name given by New- ftrufted a building in this ftyle, which has far furpaflcd, ton to the fcience of algebra ; of which he left at Cam- he fays, his own expeftation, and has certainly gained bridge an excellenc treatife, being the text-book drawn the approbation of every man of tafte and fcience by up for the ufe of his lettures, while he was profefTor of whom we have had occafion to hear it mentioned. " A mathematics in that univerfity. fet of pofts of adi, about three inches in diameter, were ARITHMETICAL complement, of a loga- placed in two rows, four feet afunder, and at the inter, rithm, is what the logarithm wants of lO'ooooo, &c. val of four feet in the rows ; then a number of (lender and the eafieft way to find it is, beginning at the and tapering willow rods, ten feet in length, were ap- left hand, to fubtraft every figure from 9, and the la(t plied to the pofts, and, in the manner which we have from 10. defcribed, formed into a frame, which being covered ARTEDI (John), was born in the year 1705, lit with thatch, produced a very fubftantial roof, under the province of Angerinania, in Sweden. From na- which a perfon can walk with eafe. " This little ftrufture exhibits, in miniature, all the charafterillic features of the Gothic ftyle. It is in the form of a crofs, with a nave, a choir, and a north and fouth tranfept. The thatch, being fo difpofed on the frame as not to hide the rods of which it is compofed, they reprefent accurately the pointed and femicircular arches, and all the other peculiarities of a groined roof." ARCTUS, a name given by the Greeks to two con- ftellations of the northern hemifphere,.,.by the Latins called Ursa Major and Minor, and by us the Greater and l.ejfer Bear. Binary ARITHMETIC. See Binary Arithmetic, Encycl. Duodecimal Arithmetic, is that which proceeds from 12 to 12, or by a continual fubdivifion according to 12. This is greatly ufed by moft artificers in calculating the quantity of their work ; as bricklayers, carpenters, painters, tilers, &c. Harmonica! /Jrithmetic, is fo much of the dottrine of numbers as relates to the making the comparifons, reduftions, &c. of mufical intervals. Arithmetic of infinites, is the method of fumming up a feries of numbers, of whicli the number of terms is infinite. This method was firft invented by Dr Wal- lis, as appears by his treatile on that fubjeft ; where he (hows its ufes in geometry, in finding the areas of fuperficies, the contents of folids, &c. But the method of fluxions, which is a kind of univerfal arithmetic of infinities, performs all theie more eafily, as well as a great many other things, which the former will not reach. JLogiJlical Arithmetic, a name fonietimes employed for the arithmetic of fexagefimal fraitions, ufed in aftro- nomical computations. Shakerly, in his TabuU Bri- tannicte, has a table of logarithms adapted to fexagefi- mal fraftions, which he calls logljlital logarithms : and the expeditious arithmetic, obtained by means of them, ke calls logiflical arithmetic. The term /ogijlical arith- SuppL/ Vol. I. Part I. ture he inherited an ardent pallion fir all branches of natural hiftory, but he excelled moll in that branch of it which is termed itchlhyology. In 1724 he went to ftudy at the univerfity of Upfal, where fome years after- wards he gained the friendlhip of the immortal Linna;us, who narrates the principal events of his life in the fol- lowing animated terms. " In 1728 (fays Linnasus) I came from Lund to Upfal. I wiihed to devote myfelf to medicine. I in- quired who, at that univerfity, excelled moil for his knowledge : every one named Artedi. I was impa- tient to fee him. I found him pale, and in great di- ilrefs for the lofs of his father, with his thin hair ne- glefted. He refembled the portrait of Ray the natu- ralift. His judgment was ripe, his thoughts profound, his manners fimple, his virtues antique. The converfa- tion turned upon (tones, plants, animals. I was enchant- ed with his obfervations, equally ingenious and new ; for at the very firft he was not afraid to communicate them to me with the utmoft frankiiefs. I defircd his friendfiiip, he a(ked mine. From that moment we form- ed a triendfliip ; which we cultivated with the greateft ardour for ("even months at Upfal. I was his belt friend, and I never had any who was more dear to me. How fwect was that intimacy ! With what pleafure did we fee it increafe fiora day to day ! The difference, even of our charadlers, was ufeful to us. His mind was more fevere, more attentive ; he obferved more (lowly, and with greater care. A noble emulation animated us. As I defpaired of ever becoming as well inftrufted in chemittry as he, I abandoni-d it ; he alfo ceafed to ftu- dy botany with ttie fame ardour, to which I had devo- ted myfelf in a particular manner. We continued thus to ftudy different branches of fcience; and when one of us excelled the other, he acknowledged him for his mafter. We difputed the palm in ichthyology ; but foon I was forced to yield, and I abandoned that part of natural hiftory to him, as well as the amphibia. I fucceeded better than he in the knowledge of birds and E infefts. ART Arted!. infefts, and he no longer tried to excel in tliefe branch- We inarched together as equals in lithology, and the hiftory of quadrupeds. When one of us made an obfervation, lie communicated it to the other : fcarce a day paffed in which one did not learn from the other fome new and interefting particular. Thus emulation [ 34 1 ART this great ichthyclogift, who had ever delighted ia that element." ^ Of the works of this eminent naturalift there have been two editions, of which the former was pubhTned by Linnsus in 1 738, and the latter by Dr Walbaum of Lubeck, in tlie years 178?, 1789, and 1792. This excited our induftry, and mutual affiftance aided our ef- edition, which is by much the moft valuable, is in three forts. In fpite of the dlftance of our lodgings, we faw volumes 410 ; of which the firfl contains the hiHory of each other every day. At laft I fet out for Lapland ; the fcience of ichthyology, commencing feveral years he went to London. He bequeathed to me his manu- before the Chriftian era, and comir.g down to the pre- fcripts and his books. fent times. The fecond prefents to the reader the " In 17^5 I went to Leyden, where I found Ar- Philofophia Ichthyologtca of Artedi, improved by Wal- tedi. I recounted my adventures ; he comm.unicated his baum, who was benefited by the writings of iionro, to me. He was not rich, and therefore was unable to Camper, Kaetfeuter, and others. Here alfo are added Be at the expence of taking his degrees in phyfic. I recoinmended him to Seba, who engaged him to pubUfh his work on fifhes. Artedi went to join him at Am- fterdam. " Scarcely had I finilhed my Fundamtnta Botanica. I communicated it to him; he let me fee his Philofophia Jchthyalogica He propofed to finilTi as quickly as pof- fibk the work of Seba, and to put the laft hand to it. He fhowed me all his manufcripts which I had not feen. r was prefTed in point of time, and began to be impa- tables containing the fyftem of fifhes by Ray, Dale, Schaeffir, I^innjEus, Gowan, Scopola, Kltin, and Gro- novius. The third volume, which completes the col- ledlion of Artedi's works, contains the technical defini- tions of the fcience. After the generic and individual charafters come the names and Latin phrafes of Ar- tedi ; the fynonymes of the beft naturalifts ; the vulgar names in Er.glilh, German, Swedifh, Rullian, Danifli, Norwegian, Dutch, and Samoj cd ; the feafon and the countries where every kind is found, their varieties. tient as being detained fo long. Alas ! if I had known their defcription, and obfervations. The modern difco- this was the laft time I (hould fee him, how (hould I veries, even to our own times, are added ; fo that in have prolonged it ! this part is collected the obfervations of Gronovius> " Some days after, as he returned to fup with Seba, Brunich, Penant, Forfter, Kleki, Bloch, Gnieh'n, Haf- the niu-ht being dark, he fell into the canal. Nobody fclquill, Brouffonet, Lelke, Builh, Linnseus, and other perceived it, and he perifhed. Thus died, by water, great examiners of nature. Artedi. ASTRONOMY r fS a fcience which has been cultivated from the ear- lieft ages, and is converiant about the moft fublime objects of inquiry which can employ the mind of man. It has accordingly been treated at great length in the Encyclopaedia Britannica ; but, in the opinion of fome of the moft judicious readers of that work, the compiler of the fyftem whicli is there delivered has failed in liis attempt to give a perfpicuousand connefled view of the .' fcience in its prefent ilate of improvement. This dcfeft ^jedl of .^ .^ ^^^ j^^y ^^ remedy. Our objetl, therefore, in this ' fupplementary article, will be to bring into one point of view the phyfical fcience which may be derived from the confideration of the celeftial motions ; that is, to deduce from the general laws of thofe motions the in- ferences with refpecl to their fuppofed caufes, which conft-itute the phllofophy of the aftronomer. Tiie caufes of all phenomena are not only inferred from the phenomena, but are charaiTlerifed by them ; and we can form no notion of their nature but what we conceive as competent to the phenomena therafelves. The allronomical phenomena are affumed to be the mo- tions of the boilief, which we call the fun, the p/anets, the comeis, &c. The notion which we exprefs by the word loJy in the prefent cafe, is fuppofed to be the fame with that which we form of other objefts around us, to which we give the fame name ; fuch as ftones, fticks, the bodies of animals, &c. Therefore the notion which we have of the caufgs of the celeftial motions muft be the fame with that which we have of the caufes of motion in thofe more familiar bodies. All men feem to have Vlewphori. agreed in giving the name FoacEs, or moving forces, c^l ufe of to the caufes of thofe familiar motions. This is a fi.taeteim- gurative or metaphorical term, 'i'he true and otiginar meaning of it is, the exertion which we are confcious of making when we ourfelves put other bodies in motion. Force, when ufed without figure, always fignifies the exertion of a livii g and afting thing. We are more- interefted in thofe productions of motion than in any other, and our recoUedlions of them are more numerous. Hence it has happened that we ufe the fame term to, exp'.efs the caufe of bodily motion in general, and fay that a magnet has force, that a fpring has force, that a moving body has force. Our own force is always exerted by the intervention of our own body ; and we find that the lame exertion by which we move a ftone, enables us to move another man ; therefore we conceive his body to refcmble a ftone in this refpeft, and that it alfo requires the exer- tion of force to put it in motion. But when we refledt on our employment of force for producing motion in a body, we find ourfelves puzzled how to account for the motion of our own bodies. Here we perceive no in- tervening exertion but that of willing to do it ; yet w^ fi^nd that we cannot move it as we pleafe. We alfo find that a greater motion requires a greater exertion. It is therefore to this exertion that the reflefting man re« ftraiiis th>' term forci- ; and he acknowledges that every- other uie of it is metaphorical, and that it is a refem- blance ASTRO blance in the ultimate cfFeft alone which difpofcs us to employ the term in fuch cales : but we find no great inconvenience in the want of another term. We farther find, that our exertion is nccefTary, not only for producing motion where there was none be- fore, but alfo for producing any change of motion ; and accurate obfervation thews us, that the fame force is required for changing a motion by any given quan- tity, as for producing that quantity where there was none before. Laftly, we are confcious of exerting force when we refill the exerted force of another; and that an exertion, perfedfly fimilar to this, will prevent fome very familiar tendencies to motion in the bodies around us : thus an exertion is necefi'ary for carrying a weight, that is, for preventing the fall of that weight. All thefe refcmblances between the effefts of our for- cible exertions and the changes of motion which ac- company the meeting, and fometimes the mere vicinity of other bodies, juftify us in the ufe of this figurative languaire. The refemblance is found to be the more perfeft as we obferve it with more care, and, in Ihort, appears to be without except oi. Bodies are therefore faid to aS on each other, to rcj'ifi each other, to rejijl a change of motion, &c. Therefore, wherever we obferve a change of motion, we infer the exiftence and exertion of a changing force; and we infer the diredlion of that exertion from the di- redlion of the change ; and the quantity of the exer- tion, or intenfity of the force, from the quantity of the change. The ftudy of the caufes of the celeftial motions is therefore hardly different from the ftudy of the motions themfelves; lince the agency, the kind, and the degree of the moving force, are immediate inferences from the exiftence, ilie kind, and the quantity of the change of motion. Our 1' tion O""" notion of a moving power is that of a power ofamovinj! which produces motion, that is, a fuccefiive change of power. place. Continuation of the motion produced is there- fore involved in the very notion of the production of motion ; therefore the continued agency of the moving power, or of any power, is not neceflary for the conti- nuation of the motion. Motion is confidered as a ftate or condition of the body ; there is not any exertion of power therefore in the continuation of motion : But every change is indicative of a changing caufe ; and ■when the change is the fame, in all its circumftances, the caufe is neceffarily conceived to be the fame, or tqual. The condition of a body, in refpeft of motion, can differ from that of another equal body only in its di- redlion and in its velocity. If the dlrefiions are the fame, the difference of conditions can only be in the difference of velocity. One body has a determination, by which it would defcribe ten feet uniformly in a fe- cond, if nothing changed this determination; the other ^ has a determination, by which it would defcribe twenty Weafure of feet in a Iccond. Each of thefe determinations are fup- movmg pofed to be the effefts of forces afting fimilarly in every refpeft Therefore thefe determinations are the only meafures of thefe two forces; that is, moving forces are conceived by us as having the proportion of the veloci- ties which they produce in a body by afting in a man- nsr perfectly fimilar. 35 N O M Y. We can conceive a force afliiig equally or unequally. If we fuppofe it to a£l equally or uniformly, we fnp- pofe that in equal times it produces equal effedts ; that is, equal determinations, or equal changes of dctermina. tion. We have no other notion of equality or unifor- mity of adlion. Therefore it mull produce equal aug- mentations or diminutions of velocity ill equal times j theref jre it muft produce an un'ifennly accelerated or re- > tarded motion. Uniformly accelerated or nnarded mo- Arcciera. tion is, therefore, the mark ot uniform or unvaried ac-''- nii.iioii tion. In fuch a motion, the chansjes i-t velocitv are' "^"'^''^O' , , V , ,° . . . ,' unvaried proportional to tlie times trom the bcginni:-.g or the ac- jccion • tion; and if the motion has begun from reft, the whole acquired velocities are proportional to tiie times from the beginning of the motion. In this cafe, the fpaces delcribed are as the fquares of the times from the be- ginning of the motion ; and thus we arrive r.t an often- fible mark of the unvaried adlion of a moving force, viz. fpaces increafing in the duplicati ratio of the times: ■ for fpace and time are all that we can immediately ob- ferve in any motion that is continually varying ; the velocity or determination is only an inference, on the fuppofition that the motion continues unchanged for fome time, or that all action ceafcs for fome time. This abftrafl reafoning is perfedlly agreeable to every phenomenon that we can obferve with diftindlnefs. Thus we cannot, or at leaft we do not, conceive the weight of a body to vary i^s adlion during the fall. We confider this weight as the caule of the tall — as the moving force — and we conceive it to adl uniformly. And, in fadl, a body falling freely, dcfcribes fpaces which are proportional, not to the times, but to the fquares of the times, and the fall is a motion uniformly accelerated. In like manner, the motion ot a body riTing in the air, in oppofition to gravity, is uniformly retarded. ^ This kind of motion alfo gives us a certain meafure And pivcj of the acquired velocity, although there is not, in fadt, ■' . eafure any fpace obferved to be uniformly delcribed during '^'' any time whatever. in this motion we know that the final determination, produced by the accumulated or continued adlion of the unvaried force, is fuch that the body would defcribe uniformly twice the fpace which it has defcribed with the accelerated motion. And it is by tliis method that we obtain the fimplcfl meafure of any moving force, and can compare it with another. If we obferve that by the adlion of one force (known to be uniform by the fpaces being proportion- al to the fquares of the times) ten feet have been de- fcribed in a fecond, and that by ttie uniform adlion of another force eighty feet are defcribed in two feconds, we know that the lafl force is double of the fiifl : for in the fecond motion. So feet were defcribed in two fe- conds, and therefore 20 feet of this were defcribed in the firfl fecond (becaufe the motion is uniformly acce- lerated ; and at the end of a fecond, the firft body had a determination by which it would defcribe 20 feet uniformly in a fecond ; and the fecond body liad ac- quired a determination by which it would liave de- fcribed 40 feet uniformly in the next ftcoiid, had not the moving force continued to adl on it, and n.adc it really defcribe 60 feet with an accelerated motion. Becaufe halves have the fame proportions with the units of whicii ttiey are the halves, it is plain that we may take the fpaces, defcribed in equal times with mo £ 3 tiont qu red ve- locity. 36 ASTRO tions uniformly aecelernted, as meafures of the forces which have produced thile motions. The velocities 7 generated are, however, the bed meafures. Meafure of When the adlions of forces are not uniform, it is the velocity jj,Qfg difficult to learn what is the meafure of the velo- bv ad^ion ''''5' produced by their accumulated aftion. But it can tiot uni- he determined with equal accuracy; that is, we can de- form, termine wliat is the velocity which lunuld have been pro- duced by the uniform aftiou of the force during the fame time, and tlierefore we obtain a meafure of the force. Mathematicians are farther able to demonflrate, that if forces vary their continued aftion in any manner what- ever, the proportion of the fpaces defcribed by two bo- dies in equal times approaches nearer and nearer to the proportion of the fpaces which they would defcribe in thofe times by the uniform aftion of the forces, as the times themfelves are fmaller ; and therefore whenever we can point out the ultimate ratio of the fpaces de- fcribed in equal limes, thefe times being diminifhed without end, we obtain the ratio of the forces. Motions may be changed, not only in quantity, by acceleration or retardation, but alfo in direftion, by de- Hefting a body from its former direftion. When a ■plate VI. body, moving uniformly in the direftion AB (fig. i.), has its motion changed in the point B, and, inflead of defcribing BC uniformly in the next moment with the former velocity, defcribes BD uniformly in that mo- ment, it is plain that the motion BD will be the fame, whether the body had begun to move in A, or in F, or in G, or in B, provided only that its determination to move, or its velocity, be the fame in all thofe points. Complete the parallelogram BCDE. It is well known, that if one force aft on the body which would make it defcribe BC, and another which would make it defcribe Intenfity ■^^' ^^^ body will defcribe BD. Hence we learn, and direc- that when a body has the motion BC changed into the tion of de- motion BD, it has been afted on in the point B by a fleifting force which would have caufed a body at re II in B to defcribe BE. Thus we can difcover the intenfity and direftion of the tranfverfe force which produces any de- fleftion from the former direftion. In general, the force is that which would have produced in a body at reft that motion BE, which, when compounded with the former motion BC, produces the new motion BD. Thefe two principles, viz. ift, that forces are propor- tional to the velocities which they produce in the fame circumftances, and, zd, the compofition of motion or forces, will ferve for all the phyfical inveftigations in aflronomy. All the celeftial motions are curvilineal, and therefore are inftances of continual defleftion, and of the continual aftion of tranfverfe or deflefting forces. We muft therefore endeavour to obtain a general mea- fure of fuch continual deflefting forces. Meafure of Let two bodies A and a (fig. 2.) defcribe in the fame thefe forces time the arches AC, a c of two circles. They are de- obtained, flefted from the tangents AB, ab. Let us fuppofe that the direftion of the deflefting forces is known to be that of the chords AE, a e oi thefe circles. Let thefe be called the deflective chords. Draw CB, ch pa- rallel to AE, ae, and CD, cd parallel to AB, ab. Join AC, ac, CE, and c e. Tt is plain that the angle BAC is equal to the angle CEA in the alternate feg- ment. Therefore ACD is alfo equal to it ; and, be- caufe the angle CAD is common to the two triangles CAD and EAC, thefe two triangles are fimilar, and N O M Y. AD : AC = AC AE, and AD = ~. For fimi- A AE and b c z^ —. ae Therefore BC : i ^ = lar reafons a (/ = — , But AD and a , we have V" : v~=zp'' : P^, and therefore F :/ = / Xc : P' X C. T/ie centripetal forces in different points of an orhit are in the ratio com- pounded of the inverfe duplicate ratio of the perpendiculars dranvn to the tangents in thofe points from the centre of forces, and the inverje ratio of the dcfledive chords of the 17 equicurve circles. Law of We are now in a condition to determine the law of action of aftion of the centripetal force by which a planet is re- . r ' ' tained in its orbit round the fun, or the relation which ' fubfills between the intenfity of its aftion and the di- ftance of the planet from the fun : for we know the el- liptical figure of the orbit, and we can draw 3 tangent to it in any point, and a perpendicular from the iun to that tangent. Kepler's fecond law or obfervation of the planetary motions was, that each primary planet defcribed an ellipfe, having the fun in one focus. It is eafy to lliow, even without any knowledge of the geometrical properties of the ellipfe, what is the proportion of the intenfitics of the deflefting force at the aphelion and perihelion (fee fig. 4.) At thofe two points of the orbit, the motion of the planet is at right angles to the line joining it with the fun. Therefore, fince the areas defcribed in equal times are equal, the arches defcribed in equal times mull be inverfely at the dillanccs from the fun ; or the velocities mull be inverfely as the diilances from the fun. But the curvature in the aphelion and perihelion is the fame ; and therefore the diameters of the equi- curve circles in thofe points are equal. But thofe dia- meters are, in this particular cafe, what we called the defleftive chords. Therefore, calling the aphelion and perihelion diflances D and d, the velocities in the aphe- lion and perihelion V and -v, let the common defledlive chord be C. Then we have F :/ = V= X C : i)* X C, = V^ : XT', := d'^ : D'. That is, the forces which de- fleft the planet in the aphelion and perihelion are in- verfely as the fquares of the diflances from the fun. A N O M Y. perfon almofl ignorant of mathematics may fee the trutu of this by looking' into a table of natural verfcd fines. He will obfcrve, that the verfed fine of one degree is quadruple the verfed fine of half a degree, and fixteen times the ve; fed fine of a quarter of a degree ; in fhort, that the verfed fines of fmall arches are in the propor- tion of the fquares of the arches. Now fince the arches defcribed in equal times are inverfely as the diflances, their verfed fines are inverfely as the fquares of the di- flances. But thefe verfed fines are the fpaccs through which the centripetal forces at the aphelion and peri- helion defleft the planet from the tangent. There- fore, ?cc. Thus we have found, that in the aphelion and peri- helion the centripetal force afts with an intenfity that is proportional to the fquares of the diflances inverfely. As thefe are the extreme fituations of a planet, and as the proportion of the aphelion and perihelion diflances are conifiderably different in the different planets, and yet this law of a£lion is obferved in them all, it is rea- fonable to imagine that it holds true, not in thofe fitua- tions only, but in every intermediate fituation. But a conjefture, however probable, is not fufBcient, when we aim at accurate fcience, and it is neceffary to exa- mine whether tliis law of aftion is really obferved in every point of the elliptical orbit. „ For this purpofe it is neceffary to mention fome geo- Dem„n(jrj. metrical properties of the ellipfe. Therefore let ADBE ted with re- (fig. 4.) be the elliptical orbit of a planet or comet, '^P'^'^ '" '''* having the fun in the focus S. Let AB be the tranf-^*'' • verfe axi.s, and DE the conjugate axis, and C the centre. Let P be any point of the ellipfe. Draw PS through the focus. Draw the tangent PN, and SN from the focus, perpendicular to PN. Draw PQ^per|)endicular to PN, meeting the tranfverfe axis in Q. Draw QO parallel to PN, meeting PS in O. Alfo draw QR per- pendicular to PS. Bifea PO in T. It is demonftrated in the treatifes of conic feiflions, that PO is one half of the chord of the equicurve or ol- culating circle drawn through the point P. Therefore PO is one half of the defledfive chord of the planetary orbit. It is alfo demonftrated, that PR is one half of the parameter or latus re8um of the tranfverfe axis AB, or that it is the third proportional to AC and DC. Therefore PR or D r is of the fame conflant magni- tude, ill whatever part of the circumference the point P is taken. It is evident that the triangles NSP, RPQj and QPO, are all fimilar, by reafon of the parallels PN, QO, and the right angles SNP, PRQ, PQO. Therefore we have PR : Pt|^= PQj PO. Therefore PR : PO = PR= : PQ^N = SN' : SP^ Therefore PR X SP' = PO X SN'. But the htus reSum L is equal to twice PR, and the defleftive chord C is equal to twice PO. Therefore L X SP' = C X SN'. But we have feen, that when a curve is defcribed by nieans of a cen- tripetal force, fo that areas are defcribed proportional to the times, and therefore the velocities are reciprocal- ly proportional to the perpendiculars drawn from the centre of forces to the tangents, the forces are inverfely proportional to C X SN'. Therefore, in the elliptical motion of the planets, the forces are inverfely propor- tional to L X SP' ; and fince L is a conftant quantity, the centripetal forces are inverfely proportional to SP', or to the fquares of the diflances from the fun. Thus »9 ASTRO Thus it appears that, with refpeft to any individual planet, the centripetal force which continually defleds it from the tangent to its orbit diminilhes in the inverfc Obferveiin duplicate ratio of the diftance from the fun. The lame the motion thing is obferved to be very nearly true in the moon's •f'l^^""^"" motion round the earth, and in the motion of fuch fa- tellites of Jupiter and Saturn as defcrihe orbits which are fenfibly elliptical. It is nlfo obferved in the motion of the comets, at leaft in that which appeared in 1682 and in 1759. It was therefore very natural for Sir Ifaac Newton to examine whether the like diminution of force obtained in the adion of this force on different planets ; that is, whether the defleftlon of the earth from the tangent of its orbit was to the fimultaneous delleiflion of Jupiter as thf fquare of Jupiter's diftance from the fun to the fquaie of the earth's diftance. This was very probable, but by no means certain. Its probability is very great indeed, when we know that a comet moves fo in its or- bit that its defletlions in equal times are inverfely as the fquares of its dillances from the fiui, and that the comet palfes through the orbits of all the planets ; and when at the fame diftance from the fun as any one of them, it fuffers the fame deflexion with it. Newton therefore calculated the aflual fimultaneous defleftions of the different planets, and found them agreeable to . ,^? this law. But it was defirable to obtain a demonftra- And r)e- . . , . . r • • 1 mi • monftrated tion ot this important propolition m general terms. 1 nis in general was fupplled by Kepler's third general ol)fervation of teims. (},e motions, viz. that the fquares of the periodic times of the different planets 'were proportional to the cubes of their mean dijlances from the fun. The orbits of the planets are io nearly circular, that we may_ fuppofe them ex- adly fo in the prefcnt queflion, without any remark- able error. In this cafe, then, the defledlive chords are the diameters of the orbits (for DS is equal to AC), and are proportional to the diilances, which are their halves. The centripetal forces, being proportional to — , are proportional to —7, when d is the radius of the orbit, or the mean diftance from the fun. But the ve- locity in a circular orbit is as the circumference direflly, and as the time of a revolution inverfely. Therefore, . 'Z' r ■ inftead of •»% we may write *-r, and then the forces will be proportional to — , or to — ; that is, direftly as the ^ '^ t^d t^ diftances, and inverfely as the fquares of the times of re- volution. But, by Kepler's obfervation, f is propor- tional to d3. Therefore the centripetal forces are pro- portional to —7, or to -J-; ; that is, inverfely as the fquares of the mean diftar.ces from the fun. But fince the orbits of the planets are not accurate circles, this determination is but an approximation to the tiuth, and therefore infufficient for the foundation of fo important a propofition ; at any rate, it will not apply to the comets, whofe orbits are very far from be- ing circular. We muft obtain a more accurate demon- ftration. Therefore draw SD (fig. 4.) to the extremity of the conjugate axis, and bifeflr it in t. About S, with the radius SD, defcrihe the circle DFG. Let D J, D J be equal fmall arches of the ellipfe and the circle. Join N O M Y. 39 d S, J S. It is well known that DS Is h ilf of the chord of the equicurve circle at D, and therefore D/ is one fourth part ot it. It ha-, been demoiiftrated, that the velocity in any point D of a curve, delctibcd by means of a deflexbting force, is that which the force in that point would communicate to it by uniformly impelling it along the fourth part of the delleclive chord, that is, along D /. But if a body revolved round S in a circle DFG, its velocity in that circle would be that which the defledling force would communicate to it by uni- formly impelling it along one-fourth of the diameter, that is, along Tit. Therefore the planet, if pri.je6\ed in the direftion D J, with the velocity which it has in the point D of the ellipfe, would defcrihe the circle DFG by the art ion of the centripetal force. Farther, it would del'cribe it in tiie fame time that it defcribes the ellipfe ; for becaufe the velocities are equal, tiie areas DS^/, DS "f are defcibed in the fame time. But the bafes Y) d, D J being equal, thefe areas are as their heights Sn (or CD), and SD (or CA). But becaufe the diameter of the circle is equal to AB, the area of the whole ellipfe is to the area of tlie circle as CD is ta CA ; that is, as the area DS d to the area DS J de- fcribed in the fame time. Therefore the elliptical and circular areas are fimllar portions of the ellipfe and cir- cle ; and therefore the times of defcribing them are fi- milar portions of the whole revolutions in the ellipfe. and in the circle. Therefore thefe revolutions are per- formed in equal times. And thus it follows, that if all the planets and co- ' mets were projefted, when at their mean diftances from the fun, perpendicularly to the radii vetlores, they would defcribe circles round the fun, and the fquares of their periodic times would be proportional to the cubes of their mean diftances from the fun, as Kepler has ob- ferved ; and therefore the centripctid forces would be inverfely as the fquares of their diftances from the fun. „ They are not different forces therefore which retain All the pJa- the different planets in ttieir refpirclive orbits, but one"'^'' '^^*;''- force, aftingby the fame law upon them all. We mayrefpefliv^ either conceive it as an attraffive force, exerted by the orbit* by fun, or as a tendency m each planet; nay, nothin«-one and the hinders us from conceiving it as a force external, both'^*™' "' to fun and planets, impelling them towards the fun. It may be the impiilfe of a ftrcam of fluid moviu'T conti- nually towards the fun. Sir Ifaac Newton did not con- cern himfelf with this queftion, but contented himfelf with the difcovery of the law according to which its ac- tion was exerted. The fteps of this inveftigation fliew- ed him, that a body, projected in any direction what- ever, and with any velocity whatever, and fubjefted to the aClion of a force directed to the fun, and inverfely proportional to the fquaie of the diftance from the fun, will neceffarily defcribe a conic feftion, having the fun in the focus. This will be a parabola, if the velocity of projeftion be that whlcli the centripetal force in that place would communicate to the body by afting on it uniformly along a line equal to half its diftance from the fun. If the velocity be greater than this, the path will' be a hyperbola ; If the velocity be lefs than this, the path will be an elliptical orbit, in which the body will revolve for ever round the fun. The 3d Keplerean law is alfo obferved in the revolu- tion* of the fateliites of Jupiter, Saturu, and the lately sJifcovered; 40 ASTRONOMY. •lifcovered planet ; and we mud infci- from it, that they cal motion round the earth. At new moon, her ten- a: are retained in their orliits round their refpcitive pri- dency to the fun exceeds the earth's tendency to him, ""' «•''- mary planets, by forces whofc intenfity decreafes ac- and this excefs will diminifh her tendency to the earth, gf^^.""^ cording to the fame law of the diftanccs. Alfo the el- and her motion will be lefs incurvatcd, fo that fhe moon's liptioal motion of the moon round the earth, fiiews that will retire a little from the earth. At full moon, the tnotion the force by which (he is retained in her orbit varies in earth's tendency to the fun exceeds the moon's tendcn- the fame proportion of the diilances. But when we cy to him, and the earth will feparate a little from the compare the motion of a fatellite of Jupiter with that moon, fo that the relative orbit will again be lefs incur- of one of tl)e fatellitcs of the other two planets, we lind vated. In the quadratures, the impulfe on the moon Is that the proportion does not hold. We (hall find that, indeed equal to that on the earth, but not parallel, and at equal diftanccs from Jupiter and Saturn, the force tends to make the moon approach the earth, and increafe tcjward Jupiter is almoft thrice as great as the force to- the curvature of her orbit. In other fituations of the ward Saturn. We fliall alfo find that the force toward moon, this want of equality and parallelifm of the forces Jupiter is three hundred times greater than the force ading on the earth and moon, muft produce other dif- which retains the moon in its elliptical orbit round the turbances of the regular elliptical motion. earth, when afting at the fame dillance. Newton faw this at once ; and, to his great delight. Since a force direftcd to the fun, and inverfely as the he faw that the great deviations from regular motion, fquare of the diilance, is thus found to pervade all the which had been difcovered by Ptolemy and TychoBrahe, planetary orbits, it is highly improbable that it will not called the Annual Equation , the Variation, and the Evec- affcft the fecondary planets alfo. The moon accompa- tion, were fuch as moft obvioufly refulted from the re- nies the earth in its motion round the fun. It may ap- gular influence of the fun on the moon. The firft de- pear fufRcient for this purpofe, that the moon be re- viation from the regular elliptical motion is occafioned tained in its orbit by a force direfted to the earth. Were by the increafe of the fun's difturbing force as the earth the moon connefted with the earth by a rope or chain, approaches the perihelion ; and it enlarges the lunar or- this would be true ; for the earth could get no motion bit, by diminifhing the tendency to the earth, and in- without dragging the moon along with it : but it is creafes the periodic time. The fecond arifes from the quite otherwile with bodies moving in free fpace, with- direction of the difturbing force, by which it accelerates out any material connexions. When a body that is the moon's angular motion in the fecond and fourth moving uniformly in a ftraight line is accompanied by quadrants of her orbit, and retards it in the firft and another which defcribes around it areas proportional to third. The lall affedls the eccentricity of the orbit, by the times, the force which coniinually deflefts this fa- changing the ratio of the whole or compound tendency tellite is always direfted to the moving central body.' of the moon to the earth in her perigee and apogee. This is eafily feen ; for whatever be the mutual aftion This fuccefs incited him to an accurate examination of ,, of two bodies, and their relative motions in confequence the confequences of this influence. It is the boaft of May becat- fuMcaad to'-^f this aiSion, if the fame velocity be imprefled at once this difcovery of the law of the planetary defleflions, culited this folar on both bodies in the fame direilion, their mutual ac- that all its effefts may be calculated with the utmoft ^"'.i." P"'*" tions and relative motions will be the fame as they precifion. The part of the moon's defleftion toward would have been without this common impulfe. Thus the fun, which is neither equal nor parallel to the fimul- every thing is done in a fliip that is failing fteadily in taneous defleftion of the earth, may be feparated from the fame manner as if ftie were at reft. If therefore the the part which is equal and parallel to it, and it may moon be obferved to defcribe areas round the earth, be called the fun's difturbing force. Its proportion to which 2X^ precifeh proportional to the times, while the the moon's defleftion towards the earth may be accu- earth moves in an orbit round the fun, we muft infer that rately afcertaincd, and its inclination to the line of the the moon receives, in every inftant, an .impulfe the fame moon's motion in every point of her orbit may be point- in every refpeft with what the earth receives at the fame ed out. This being done, the accumulated effedl of inftant; or that the moon is afted on by a force paral- this difturbing force after any given time, however va- lel to the earth's diftance from the fun, and proportion- riable, both in direftion and intenfity during this time, al to the fquare of that diftance inverfely. Now this may be determined by the 39th and other propolitionsof is very nearly true of the lunar motions ; and we the firft book of the Mathematical Principles of Natural muft infer that the moon is fubjefted to this folar ac- Philofophy. And thus may the moon's motion, when The latel- Iitcs of" aU adtion. tion, or this tendency to the fun. The fame muft be affirmed of the fatellites of the other planets. But a force inverfely proportional to the fquare of the earth's diftance from the fun is not what the univer- fo difturbed, be determined and compared with her mo- tion really obferved. All this has been done by Sir Ifaac Newton vi-ith the moft aftonifhing addrefs and fagacity,yi/3 malheji Jacem (ality of the law requires: It muft be inverfely as the prefennle, partly in the Principia, and partly in his fquare of the moon's diftance from the fun; and it muft Lun^e Theoria. This invelligatlon, whether we con- iiot be parallel to the earth's diftance from the fun, but fider the complete originality of the whole procefs, or mud be direfted toward the fun ; and therefore, in the the ingenuity of the method, or the fagacity in feeing (juadratures, it muft converge to the earth's radius -oec- and clearly difcriminating the different circumftances of t'jr. Therefore, fince a force having the above men- the queltion, or the wonderful fertility of refource, or lioned conditions will allow the defcription of areas the new and moft refined mathematical principles and round the earth exaftly proportional to the times, a methods that he employed — muft ever be confideied as force afting on the moon, inverfely proportional to the the moft brilliant fpecimen of human invention and rea- Jquare of her diftance from the fun, and directed exaft- foning that ever was exhibited to the world. Jy to the fun, is incompatible with the accurate ellipti- In this inveftigation Newton not only determined the quantity, il* 4? The fecU' lar equa- ilance ASTRO quantity, the period, and the changes of thofe inequa- lities, which had been fo confiderable and remarkable as to be obferved by former altronomera, and this with an cxaftnefs far furpafTitig what could ever be attained by mere obfervation ; but he alfo pointed out feveral other periodical inequalities, which were too fmali, and too much implicated with the reft, ever to be difcovered or to be feparated from them. We do not fay that he completed the theory of the lunar motions; but he pointed out the methods of inveftigation, and he fur- nirtied all the means of profecuting it, by giving the world the elements of a new fpecies of mathematics, witliout which it would have been in vain to attempt it. Both this new mathematics, and the methods of apply- ing it to fuch queftions, have been affiduoufly ftudied and improved by the great mathematicians of this cen- tury ; and the lunar theory has been carried to fuch a degree of perfeftion, that we can compute her place in the heavens for any paft age without deviating above one minute of a degree from the aftual obfervation. There is one empirical equation of the moon's mo- tion which the comparifon of ancient and modern eclip- fes ohhges the aftronomers to employ, without being able to deduce it, like the reft, a priori, from the theory of an univerfal force inverfely proportional to the fquare of the diftance. It has therefore been confidered as a ftumbling block in the Newtonian philofophy. This tion of the jg ^^,1,3^ jg called the fecular equation of the moon's mean moons . rru .• • j j 1 r mean di- 'notion. 1 he mean motion is deduced from a compari- fon of diftant obfervations. The time between them, being divided by the number of intervening revolutions, gives the average time of one revolution, or the mean lunar period. When the ancient Chaldean obfervations are compared with thofe of Hipparchus, we obtain a certain period ; when thofe of Hipparchus are compa- red with fome in the 9th century, we obtain a period fomewhat (horter ; when the laft are compared with thofe of Tycho Brahe, we obtain one ftill ftiorter ; and when Brabe's are compared with thofe of our day, we obtain the fhorteft period of all — and thus the moon's mean motion appears to accelerate continually ; and the accelerations appear to be in the duplicate ratio of the times. The acceleration for the century which ended in 1700 is about 9 feconds of a degree ; that is to fay, the whole motion of the moon during the 17th centu- ry muft be increafed 9 feconds, in order to obtain its motion during the igth; and as much muft be taken from it, or added to the computed longitude, to obtain its motion during the i6th; and the double of this muft be taken from the motion during the 16th, to obtain its motion during the 15th, &c. Or it will be fuflicient to calculate the moon's mean longitude for any time paft or to come by the fecular motion which obtains in the prefent century, and then to add to this longitude the produft of 9 feconds, multiplied by the fquare of the number of centuries which intervene. Thus having found the mean longitude for the year 1200, add 9 fe- conds, multiplied by 36, for fix centuries. By this me- thod we fhall make our .calculation agree with the moft ancient and all intermediate obfervations. If we negle£l this correftion, we ftiall differ more than a degree from the Chaldean obfervations of the moon's place in the heavens. The mathematicians having fucceeded fo completely in deducing all the obferved inequalities of the planeta> SuppL. Vol. 1. Part. I. N O M Y. 4J 1.5 ry motions, from the fingle principle, that the deflcft- iiig forces diminilhcd in the invcvfe duplicate ratio of the diftances, were fretted by this excption, the reality of which they could not conteft. Many opinions were formed about its caufe. Some have attempted to de- duce it from the aftion of the planets on the moon ; others have deduced it from the oblate form of the earth, and the tranflation of the ocean by the tides ; others have fuppofed it owing to the reliftance of the ether in the celeftial fpaces; and others have imagined that the action of the defledling force requires time for its propagation to a diftance: But their deduftions have been proved unfatisfadlory, and have by no means the precifion and evidence that have been attained in the other queftions of phyfical aftronomy. At lall M. de la Place, ot the Royal Academy of Sciences at Paris, has happily fucceeded, and deduced the fecular equation of the moon from the Newtonian law of planetary de- fleftion. It is produced in the foUownng manner : Suppofe the moon revolving round tlie earth undi-™ , fturbed by any deflection toward the fun, and that thefron""^ time of her revolution is cxaftly afcertaiiied. Now let Newtoniari the influence of the fun be added. I'his diminifhes her '** "f I''^- tendency to the earth in oppofition and conjundlion, ^''^" '^^" and increafes it in the quadratures: but the diminutions ^ '°"' exceed the augmentations both in quantity and dura- tion ; and the excefs is equivalent to TTiyth of her ten- dency to the earth. Therefore this diminilhed tenden- cy cannot retain the moon in the fame orbit ; fhe muft retire farther from the earth, and defcribe an orbit which is lefs incurvated by -rrj-th part ; and (he muft employ a longer time in a revolution. The period therefore which we obferve, is not that which would have obtain- ed had the moon been influenced by the earth alone. We ftiould not have known that her natural period was increafed, had the difturbing influence of the fun re- mained unchanged ; but this varies in the inverfe tri- phcate ratio of the earth's diftance from the fun, and is therefore greater in our winter, when the earth is nearer to the fun. This is the fource of the annual equation, by which the lunar period in January is made to exceed that in July nearly 24 minutes. The angular velocity of the moon is diminilhed in general tt7> and this nu- merical coefficient varies in the inverfe ratio of the cube of the earth's diftance from the fun. If we expand tin's inverfe cube of the earth's diftance into a ferics arran- ged according to the fines and cofines of the earth's mean motion, making the earth's mean diftance unity, we fliall find that the fen'es contains a term equal to -|. of the fquare of the eccentricity of the earth's orbit. Therefore the expreffion of the diminution of the moon's angular velocity contains a term equal to T^-g- of this ve- locity, multiplied by \ of the fquare of the earth's ec- centricity ; or equal to the produtt of the fquare of the eccentricity, multiplied by the mo;)n's angular velocity, and divided by 1 19,3? (y of 179). Did this eccentri- city remain conftant, this produft would alfo be con- ftant, and would ftill be confounded with the general diminution, making a conftant part of it : but the ec- centricity of the earth's orbit is known to diminifli, and its diminution is the refult of the univerfality of the Newtonian law of the planetary defledlions. Although this diminution is exceedingly fmall, its effedt on the lu- nar motion becomes fenfible by accumulation in the courfe of ages. The eccentricity diroinilliing, the dimi- F nutioa 43 ASTRO nution of the moon's angular motion mud alfo diminifh, that is, the angular motion muft incrcafe. During the i 8th century, the fquare of the earth's tccentricity has diminilhed 0,0000015^25, the mean diftance from the fun being =: t. This has increaied the angular motion of the moon in that tinieo.ocooocc 1 285. As this augmentation is gradual, we mull multiply tiie angular moiion during the century by the halt of this quantity, in order to obtain its accumulated effeft. This will be found to be 9" very nearly, which exceeds that deduced, from a moll careful comparilon of the motion of tlie lall two centuries, only by a fraction of a fe- cond ! As long as the diminution of the fqnarc of the eccen- tricity of the earth's orbit can be fuppofed proportion- al to the time, this effefl will be as the fquarcs of the times. When this theory is compared with obferva- tions, the coincidence is wonderful indeed. The effefl on the moon's motion is periodical, as the change of the folar eccentricity is, and its period includes millions of years. Its eifeft on the moon's longitude will amount to feveral degrees before the fecular acceleration change to a retardation. Thole who are not familiar with the difquifitlons of modern analyfis, may conceive this queition in the fol- lowing manner. Let the length of a lunar period be computed for the earth's diftance from the fun for every day of the year. Add them into one fum, and divide this by their num- ber, the quotient will be the mean lunar period. This will be found to be greater than the arithmetical me- dium between the greateft and the kail. Then fuppofe the eccentricity of the earth's orbit to be greater, and make the fame computation. The average period will be found ftill greater, while the medium between the greateft and leaft periods will hardly differ from the former. Something very like this may be obferved without any calculation, in a cafe very fimilar. The angular velocity of the fun is inverfely as the Iquare of his dillance. Look into the folar tables, and the great- eft diurnal motion will be found 3673 ', and the leafl: 3433'' The mean of thefe is 3553', but the medium of the whole is 3548''. Now make a fimilar obfervation in tables of the motion of the planet Mars, whofe ec- centricity is much greater. We (hall find that the me- dium between the greateft and leaft exceeds the true medium of all in a much greater proportion. Ccrtiii ty Thus has the patient and afllduous cultivation of the and utility Newtonian difcoveries explained every phenomenon, and of this law. enabled us to forefee changes in them- which no exami- nation of the part appearances, unaflTifted by this theory, could have pofnted out, and which muft have exceed- ingly embarraUed future aftronomers This great but fimple law of defltftion reprefents every phenomenon of the fyftem in the moil minute circumftances. Far from fearing that future experience may overturn this law, we may reft alTured that it will only confirm it more and more; and we may confide in its moft remote .. confcquences as if they were aftually obferved. Reciprocal It is difcovered by obfervation, that the defleftion of deflection the moon to the earth, and of the planets to the fun, of tile tanh jr,. accompanied by an equal and oppofite defleftion of an moon, j^ earth to the moon, and of the lun to the planets, and 01 the ^ ' , . ^, . , . funandpla- The tendency 01 the earth to the moon is plainly m- nets, dicated by the rife of the waters of the ocean under the N O M Y. moon, and on the oppofite fide of the earth. Slrlfaae Newton tried what (hould be the refult of a tendency of the water to the moon. His invcftigation of this quef- tion was very fimilar to that in his lunar theory. We may conceive the moon to be one of many millions of particles of a fluid, occupying a globe as big as the lu- nar orbit. Each will feel a fimilar difturbing force, which will diminifh its tendency to the earth in the neighbourhood of the place of conjundlion and oppofi- tion, and will increafe it in the neighbourhood of the j„ quadratures. They cannot therefore remain in equdi- Proved br brio in their fpherical form ; they muft fink in the qua- 'I": ebbing dratures, and rife in the conjundtion and oppofition, till ' \ °^'^ their greater height compenfates for the diminiflied jg^ weight of each particle. In like manner, the waters of the ocean muft link on thofe parts of the earth where the moon is feen in the horizon, and muft rife in thofe which have the moon in the zenith or nadir. All thefe effecls are not only to be feen in general, but they may all be calculated, and the very form pointed out which the fnrfaee of the ocean muft alfume ; and thus a ten- dency ot every particle of the ocean to the moon, in- verfely proportional to the fquare of its diftance from it, gives us a theory of the ebbing and flowing of the fea. This is delivered in fufficient detail in the article Tide of the Encyclopaedia Britannica, and therefore need not be infifted on in this place. The fame infe- rence muft be drawn from the preceflion ot the equi- noxes produced by the aAion of the moon on the pro- tuberant matter of our equatorial regions. See Pre- cession in the Encycl. But the mutual tendency of the earth and moon is ^^^ i,y di clearly feen in a phenomenon that is much more fimple. fcrert con If we compute the fun's place in the heavens, on theP"'3t'""s- fuppofition that the earth defcribes areas proportional ,.'J place in tl to the times, we fiiall find it to agree with obiervation heavens, i at everv new and full moon : But at the firll quarter ] the fun will be obferved about 9 fecoiids too much ad- vanced to the eaftward ; and at the laft quarter he will be as much to the weftward of his calculated place. In all intermediate pofitions, the deviation of the obfenred from the computed place of the fun will be 9 feconds, multiplied by the fine of the moon's diftance from con- junftion or oppofition. In fliort, the appearances will be the fame as if it were not the earth which dtfcribed areas proportional to the times round the fun, but that a point, lying between the cirth and moon, and verv near the earth's furface, were defcribing the ellipfe round tlie fun, while the earth and moon revolve round this point in the courfe of a lunation, having the point al- ways in the line between them, in the farne manner as if tliey were on the extremities of a rod which turns round tliis point, while the point itfelf revolves round the fun. This then is the faft with refpeft to the motions ; and the earth in a month defcribes an orbit round this common centre of the earth and moon. It cannot do this unlefs it be continually deflefted from the tangent to this orbit ; therefore it is continually defleCled to- ward the moon : and the momentum of this deflcClion, that is, its quantity of motion, is the fame with that of the moon's defteftion, becaufe their diftances from the common centre are as their quantities of matter in. verfcly. Appearances perfeftly fimilar to thefe oblige us to affirm 43 3' >blerva- iuns on he rhirtl iw uf mo un. .n r«wton's xterlion f that Uw ASTRONOMY. affirm that the fun is continually deflected toward the the planet in a fimilar orbit round the fun (fuppofed planets. Aftrononiical inilruments, and the art of ob to be held faft in his place) at the fame diftance which ferviiig, have been prodigioufly improved fince Sir Ifaac really obtains between them, with this folc didVrcnce, Newton's time ; and the moil Icrupulous attention has that the periodic time will be longer, in the fnbdupli- been paid to the fun's motion, becaule it is to his place cate ratio of the quantity of matter in the f\in to the in the univerfe that continual reference is made in com- quantity of matter of the fun and planet together. A- puting the place of all tlie planets. He is fuppofed at reas will be defcribcd proportional to the times, and the reft in the common focus of all their orbits ; and the orbit will be elliptical ; but the ratio of the fcjiirires of o/yJr'DCt/ diftancc of a planet fom the fun is always con- the periodic times will not be the fame with the ratio fidered as the radius I'cSor. If this be not the cafe, of the cubes of the diftancts, unlefs all the planets arc the orbital motions contained in our tables are not the equal. abfolute motions of the planets, nor the deflexions from Thus was the attention of aftronomers direSed to a the tangents the real deflexions from abfolute reflilineal number of ^jft^an-n/ irregularities in the motion of the motion ; and therefore the forces are not fuch as we in- earth, which muft refult from this derangement of the fer from thofe miftaken deflexions. Accordingly Sir fun, which they had imagined to remain lledfafl in his Ifaac Newton, induced by certain metaphyfical confi- place. They were told what to expeX, and on what derations, afTumed it as a law of motion, that every ac- pofitions of the planets the kind and quantity of every tion of a body A on another body B, is accompanied irregularity dejiended. This was a moft Inviting field by an equal and contrary aXion of B on A. We do of obfervation to a curious fpcculatlft ; but it required not fee the propriety of this aflertion as a metaphyfical the niceft and mott expeniive inftruments, and an nnin- axiom. It is perfeXly conceivable that a piece of iron terrupted feries of long continued obfervations, fulficltnt will always approach a magnet when in its neighbour, to occupy the whole of a man's time. Fortunately the hood ; but we do not fee that this obliges us to affert, accurate determination of the folar and lunar motions that therefore the magnet will alfo approach the iron, were of the utmoll importance, nay, indifpenfably ne- Thofe who explain the phenomena of magnetifm by ceflTary for folving the famous problem of the longitude the inipulfe of a fluid, muft certainly grant that there is of a (hip at fea : and thus the demands of commercial no metaphyfical neceffity for another ftreani of fluid im- Europe came in aid of philofophical curiofity, and oc- pelling the magnet toward the iron. And accordingly cafioned the ereXion of obfervatories, firft at Green- this, and the fimilar reciprocity in the phenomena of wich, and foon after at Paris and other places, with ef- cleXrlcity, have rt/wjj'j- been confidered as deduXinns tabiilhments for aftronomers, who fliould carefully watch of experimental philofophy ; yet we obferve the fame re- the motions of the fun and moon, not negleXing the ciprocity in all the adllons of fublunary bodies ; and other planets. Newton's third law of motion is received as true, and The fortunate refult of all this folicitude has been the Confirmed admitted as a principle of reafoning. But we appre- complete eftablifliment of the Newtonian conjeXuie (for ''^ "Werva^ hend that it was hafty in this great philofopher, and fo we muft ftill think it), and the verification ol New- '""'' unlike his fcrupulous caution, to extend it to the pla- ton's aflfcrtion, that aXion was accompanied, through netary motions. He did, however, extend it, and af- the whole folar fyfteni, by an equal and contrary re- ftrted, that as each planet was dtfleXed toward tht- fun, aftion. All the inequalities of the folar motion pre- the fun was equally (in rclpeX of momentum) defleXed diXed by Newton have been obferved, although they toward each planet, and that his real motion was the are frequently fo complicated that they could never have compofition of all thoie fimultaneous dcfleXions. He been deteXed, had not the Newtonian theory direfted aflerted that there was a certain point round which the us when to find any of them pretty clear of complica- fun and his attending planets revolved ; and that the tion, and how to afcertain the accumulated refuk of orbit of a planet, which our meaiurements determined them all in any ftate of combination, by continual reference to the fuu as to a fixed body, But in the courfe of this attention to the motif the pla- vprfality and reciprocity "f the defleftions of the pla- ""' '"' nets and the fun, than he aHo fufpeded that they were continually dcfl.-Aed towards each other. He imme- diately obiained a general notion of what (hould be the more general refults of fuch a mutual aftion. They may be conceived in this way wards each other. Plate VI. Let S (fig. S-) reprefent the fun, E the earth, and I Tuoiter, dcfcribinir concentric orbits round the centre of the fyftcm. Make IS : EA = EP : SI^ Then, if IS be taken to reprefent the defleftion of the fun to- ward Jupiter, EA will reprefent the defleaioii of the Earth to Jupiter. Draw EB equal and parallel to SI, 35 , and compkte the parallelogram EBAD. ED will re- (^itirruVhprefent the difturbing force of Jupiter. It may be re- inutual «. folved into EF, perpendicular to ES, and EG m the di- tion. reftion of SE. By the tirll of thefe the earth's angu- lar motion round the fun is affefted, and by the fecond its defleftlon toward him is diminiihed or increafed. _ In confequence of this firil part of the difturbing force, the angular motion is increafed, while the earth approaches from quadrature to conjuiiftion with Jupi- ter {which is the cafe reprefented in the figure), and is diminithed from the time that Jupiter is in oppofition till the earth is again in quadrature, weftward of his oppofition. The earth is then accelerated till Jupiter is in conjunftion with the fun ; after which it is retard- ed till the earth is again in quadrature. . . The earth's tendency to the fun is dirainifhed while Jupiter is in the neighbourhood of his oppofition or conjunftion, and increafed while he is in the neighbour- hood of his ftationary pofitions. Jupiter being about 1000 times lefs than the fun, and 5 times more remote, IS muft be confidered as reprefenting ij^lootli "^ ''^^ earth's defledtion to the fun, and the forces ED and EG are to be meafured on this fcale. In confequence of this change in the earth's tenden- cy to the fun, the aphelion fometimes advances by the diminution, and fometimes retreats by the augmenta- tion. It advances when Jupiter chances to be in oppo- fition when the earth is in its aphelion; becaufe this di- minution of its defleaion towards the fun makes it later before its path is brought from forming an obtufc angle with the radius -veaor, to form a right angle with it. Becaufe the earth's tendency to the fun is, on the whole, more diminilhed by the difturbing force of Jupiter than it is increafed, the aphelion of the earth's orbit advances on the whole. .,,.„• 1 j In like manner the apheha of the inferior planets ad- vance by the difturbing forces of the fuperior : but the aphelion of a fuperior planet retreats ; for thefe reafons, and becaufe Jupiter and Saturn are larger and more powerful than the inferior planets, the aphelia of them all advance while that of Saturn retreats. In confequence of the fame difturbing forces, the rode of the difturbed planet retreats on the orbit of the difturbing planet ; therefore they all retreat on the eclip- tic, except that of Jupiter, which advances by retreat- ing on the orbit of Saturn, from which it fuffers the o-reateft difturbance. This is owing to the particular lofitjon of the nodes and the inclinations of the orbits. N O M Y. The Inclination of a planetary orbit Incrcafes while the planet approaches the node, and diminilhes while the planet retires from it. ,,5 M. do la Place has completed this dediiaion of the.4 feculia. planetary inequalities, by explaining a peculiarity in the""'')' 'J"- motions of Tunitcr and Saturn, whreh has lonff employ-R""'^ '" ed the attention of aftrononicrs. Tlie accelerations and„f j.,p,;gr retardations of the planetary motions depend, as hasand Saturn. been (hewn, on their configurations, or the relative quar- ters of the heavens in which they are. Thofe of Mer- cury, Venus, the Earth, and Mars, arifing from their mutual dcfleaions ; and their more remarkable deflec- tions to the great planets Jupiter and Saturn, nearly compenfate each other, and no traces of them remain after a few revolutions : but the pofitions of the aphe- lia of Saturn and Jupiter are fuch, that the retardations of Saturn feufibly exceed the accelerations, and the aiio- maliftic period of Saturn increafes almoll a day every century : on the contrary, that of Jupiter diminifhes. M. de la Place Ihews, that this proceeds from the pofi- tion of the aphelia, and the almoft perfea commenfura- bility of their revolutions ; five revolutions of Jupiter making 21,675 days, while two revolutions of Saturn make 21,538, diifering only 137 days. Suppofing this relation to be exaa, the theory (hews that the mutual aaion of thefe planets muft produce mutual accelerations and retardations of their mean mo- tions, and afcertains the periods and limits of the fecu- ' lar equations thence arifing. Thefe periods include fe- veral centuries. Again, becaufe this relation is not pre- cife, but the odd days nearly divide the periods already found, there muft arife an equation of this fecular equa- tion, of which the period is imm«nfely longer, and the maximum very minute. He (hews that this retardation of Saturn is now at its maximum, and is diminifliing again, and will, in the courfe of years, change to an acceleration. This inveftigation of the fmall inequalities is the moft intricate problem in mechanical philofophy, and has been completed only by very flow degrees, by the ar- duous efforts of the greateft mathematicians, of whom M. de la Grange is the moft eminent. Some of his ge- neral refults are very remarkable. He demonftrates, that fince the planets move in one direaion, in orbits nearly circular, no mutual difturb- ances make any permanent change in the mean diftan- ces and mean periods of the planets, and that the peri- odic changes are confined within very narrow limits. .. The orbits can never deviate fenfibly from circles. Noneofcillation of them ever has been or will be a comet moving in aof 'hepla- very eccentric orbit. The ecliptic will never coincide "'^'^'^5' 5' with the equator, nor change its inclination above two degrees. In (hort, the folar planetary fyftem ofcillates, as it were, round a medium ft;ate, from which it never fwerves very far. This theory of the planetary inequalities, founded on the univerfal law of mutual defleaion, has given to our tables a precifion, and a coincidence with obfervation, that furpaffes all expeaation, and infures the legitimacy of the theory. The inequalities are moft fenfible in the motions of Jupiter and Saturn ; and thefe prefent them- felves in fuch a complicated ftatc, and their periods are fo long, that ages were neceflary for difcovering them by mere obfervation. In this refpea, therefore, the theory has outftripped the obfervations on which it is founded.. Authin'i- city of tiie Indian a- ?9 Origin of ;he aftrolp- lical divi- fton of the 40 ^fljon cf lie comets, rhey are Jfedled by kc planets A S R T founded. It is very remarkable, that the periods which the Indians affign to thefe two planets, and which ap- peared fo inaccurate that they hurt the credit of the fcience of thofe ancii;nt aftronomtrs, are now found pre- cifcly fuch as muil have obtained about three thoufund years before the Chriftian era ; and thus they give an authenticity to that ancient artrononij. The periods which any nation of aftronomers affign to thofe two planets would afford no contemptible mean for deter- mining the age in which it was obferved. The foUowiug circumftance is remarkable : Suppofe Jupiter and Saturn in conjunction in the firll degree of Aries ; twenty years after, it will happen in Sagitta- rius; and after another twenty years, it will happen in Leo. It will continue in thefe three figus for ioo years. In the next 200 it will happen in Taurus, Capricornus, and Virgo ; in the next 200 years, it will happen in Gemini, Aquarius, and Libra ; and in the next 200 years, it will happen in Cancer, Pifces, and Scorpio : then all begins again in Aries. It is highly probable that thefe remarkable periods of the oppoiltions of Ju- piter and Saturn, progreffive for 40 years, and ofcilla- ting during 160 more, occafioned the allrological divi- fion of the heavens into the four trigons, of fire, air, earth, and water. Thefe relations of the figns, which compofe a trigon, point out the repetitions of the chief irregularities of the folar fyllem. M. de la Place obferves (in 1796), that the laft dif- covered planet gives evident marks of the adtion of the reft ; and that when thefe are computed and taken into the account of its bygone motions, they put it beyond doubt that it was feen by Flamftead in 1 690, by Mayer in 1756, and by Monnier in 1769. We have hitherto overlooked the comets in our ac- count of the mutual difturbances of the folar fyftem. Their number is very great, and they go to all quarters of the univerfe : but we may conclude, from the won- derful regularity of the planetary motions, when all their own mutual aftions are taken into account, that the quantity of matter in the comets is very inconfiderable. They remain but a fhort time in the neighbourhood of the planets, and they pafs them with great rapidity. Some of them have come very near to Jupiter, but left no trace of their atlion in the motions of his fatellitcs. They doubtlefs contribute, in general, tfe make the ap- fides of the planetary orbits advance. On the other hand, the comets may be confiderably affefted by the planets. The very important phenome- non of the return of the comet of 1682, which was to decide whether they were revolving planets defcribing ellipfcs, or bodies which came but once into the plane- tary regions, and then retired for ever, caufed the aftro- nomers to confider this matter with great care. Halley had fhewn, in a rough way, that this comet muft have been confiderably affefted by Jupiter. Their motion near the aphelion muft be fo very flow, that a very fmall change of velocity or direftion, while in the planetary regions, muft confiderably affeft their periods. Halley thought that the aftion of Jupiter might change it half a year. Mr Clairaut, by confidering the difturbing forces of Jupiter and Saturn through the whole revolution, fiiewed that the period then running would exceed the former nearly two years (618 days), and affigned the middle of April 1759 for the time of its perihelion. It leally pafTed its perihelion on the 12th of March, This O N O M Y. 45 was a wonderful precifion, wiien we rcficiA that the co- met had been feen but a very few days in its former ap- paritions. A comet obferved by Mr Profperin and others in 1771 has greatly puzzled the aftronomers. Its motions appear to have been extremely irregular, and it certainly came fo near Jupiter, that his momentary influence was at leaft equal to the fun's. It has not been rccognifed fince that time, although there is a great probability that it is continually among the planets. ^j. It is by no means inipolTible, nor highly improbable, Cor.fe- that in the courfe of ages, a comet may attually meetl"'"'* "f * one of the planets. The cffedl of fuch a concourfe niuft^'i'"^'" *"" be dreadful ; a change of the axis of dituiial rotation meeting, muft refult from it, and the fea muft defert its former bed and overflow the new equatorial reg:ons. The ftiock and the deluge muft deftroy all the works of man, and mort of the race. The remainder, reduced to mi- fery, muft long ftruggle for exiftence, and all remem- brance of former arts and events muft be loft, and every thing muft be invented anew. There are not wanting traces of fuch devaftations in this globe : ftrata and things are now found on mountain tops which were cer- tainly at the bottom of the ocean in former times ; re- mains of tropical animals and plants are now dug up in the circumpolar regions. Tempora mulanlur, et nos mu- tamur in illis. It is plain, that when we know the direftion and the intenfitv of the difturbing force, we can tell what will be the accumulated effedl of its aftion for any time. The direftion is eafily determined by means of the di- ftance : but how ftiall we determine the intenfity ? Since we fee that the whole waters of the ocean are detiefted toward the moon, and have fuch probable evidence that planetary defleftion is mutual ; it follows that the moon is deflefted towards cu^rydrop of water, and that a!l the matter in one body is' deflefted towards all the matter in another body ; and therefore that the deflec- tion towards the fun or a planet is greater or lels in proportion to its quantity of matter. Newton indeed thought it unreafonable to fuppoie that a planet wa- deflefted to the centre of the fun, which had no diftin- guiftiing phyfical property ; and thought it more pro- bable that the defleftion of a planet to the fun was the accumulated defleftion of every particle in the planet to every particle in the fun. But he was too fcrupulous to take this for granted. He therefore endeavoured to difcover what would be the fenfible defleftion of one fpherc to another, when each conllfted of matter, every particle of which was deflcdted to every particle of the other with an intenfity inverfely proportional to the. fquare of the diftance from it. By help of a nioft beau- Ttrii'ency tiful and fimple procefs, he difcovcred, that the ten.of fphcricai- dency of a particle of matter to a fpherical furtace, ftnil, " ''" '■'" or folid, of uniform denfity at equal diftances trom ihe^.'^^'' j. centre, was the fame as if all the particles in the fu.--rt(51Iyr-s the face, fhell, or folid, were united in its centre : heiice itqiiantit) of legitimately followed, that the mutual tendency of fphe- "'?''^'"' ^'■'*' rical furfaces, ftiells, or folids, was proportional to the '.^^'j^^^j^^^' quantities of matter in the attrafting body, and inverfe-cf tht di- ly as the fquare of the diftance of their centres; and '"'a c; of thus the law of attraftion, competent to every partlcle'*^^"' "•"'' of planetary matter, was the fame with that which tvas obferved among fpherical bodies conliftii.g oi inch mat- ter. And it is remarkable, that the inverfe duplicate ra- tio 46 ASTRO tio of tlic diilances is the onlv law that will hold, botli with refpeft to (ingle particles and to globus corapoled of fuch particles. He alfo deinonftrntcd, that a particle placed within a fphere was not affeflcd by all the flicU, whicii w;is more diftant than itfelf from the centre, be- ing equally attraftcd on every fide, and that it tended tinvard the centre of a homogenous fphere, on the fur- face of which it was j>laced, with a force proportional to its dillance from the centre. Newtoti faw a cafe in which it was pofTible to difco- ver whether the tendency of the matter of which the ■planets confided was direfted to a mathemalical centre void of any phyfical properties, or whether it was the refult of its united tendency to all the matter of the planet. He demonllrated that if the e.uth conlilled of matter which tended to the centre, it behoved it to af- fume the form of an elliptical fpheroid, in conkqucnce of the centrifugal force arifing from its diurnal motion, and that the pular axis muft be to its equatorial diame- ter as 577 to i;78 ; but if every particle tends to every other particle in the invcrfe duplicate ratio of the di- ftance from it, the form mufl. flill be elliptical, but more protuberant, and the polar axis mull be to the equato- rial diameter as J30 to 231. Then only will a column of water from the pole to the centre balance a column from the equator to the centre. He alfo fiiewed what ftiould be the vibrations of pendulums in different lati- tudes, on both fuppofitions. Mathematicians were ea- ger therefore to make thofe experiments on pendulums, and to determine the figure of the earth by the meatui-e- inent of degrees of the meridian in different latittides. The refult of their endeavours has been decidedly iu fa- vours of the mutual tendency of all matter. This has been farther confirmed by the obfervations of the ma- thematicians who meafured the degrees of the meridian in Peru, and by Dr Mafl7J Saturn - - - - - 86,16 Jupiter - - - - - 317,1 The Sun - -. . - 3.^8343- Thus' we fee that the fun is incomparably bigger than any planet, having more than a thoulaiid times as much matter as Jupiter, the mod niaffy of them all. There- is a confiderable uncertainty, however, in the proportion to the fun, beeaufe we do not know his diftance nearer than within -^s^th part. 'I'he proportions of the refl to each other are more accurate. The quantities ot matter in Mercury and Mars can only be gueffed at : the quantity in Mercury may be called 0,1, and Mars may be called 0,1 2. Venus is fuppofed nearly equal to the Earth. This is concluded from the efFeft which (lie produces on the precefllon of the equinoxes and the equation of the fun's motion. The moon is fuppofed to be about j^-th of the- earth, from the effeft flie pro- duces on the tides and the preceflion of the equinoxes, compared with thofe produced by the fun. 4J When thefe quantities of matter are introduced intoSuti's plaee the computation of the planetary inequalities, and ^^^J^nflt^nf , intenfity of the difturbiiig forces aflumed accordingly, pi^^ , j^. the refults of the computations tally fo exadlly with ob-termined fervation, that we can now determine the fun's place '^"■"i^y- for any moment within two or three feconds of a de- gree, and are certain of the tranfit of a planet within one beat of the clock ! yam Julias nulla caliglne prtegravat error ; ^teis fuperum pciutrare domos atque arJua call Scandere fublimis genii concejjit acumen. Hallev. Sir Ifaac Newton having already made the great dif- covery of an univerfal and mutual dcfle<5^ion of all the matter in the folar fyftem, was one day fpecnlating on this fubjecl, and comparing it vs'lth other defleftlons which he obferved among bodies, fuch as magnets, &c. He confidered terreftrial gravity as a force of this kind. By the weight of terreftrial bodies they kept united , with the earth. By its weight was the water of thep ogrtfaof ocean formed into a fphere. This force extended, wIth-Ntwton's out any remaikable diminution, to the tops of the hlgh-°'^'^'"'"'y "' eft mountains. Might it not reach much farther? May it not operate even at the diftance of the moon ? In the fame manner that the planetary force deflefts the moon from the tangent to her orbit, and caufes her to defcribe an ellipfe, the weight of a cannon ball dcflefts it from the line of its direcfion, and makes it defcribe a parabola. What if the defleiib'ng force which Incur- vates her path towards the earth be the fimple weight of the moon ? If the weight of a body be the fame with the general plmetary force. It will dimhnni as the fquare of it& diftance from the earth increafes. Therefore, faid he to himfelf, fince the diftance of the moon from the centre of the earth is about 50 times greater than the dillance of the ilone whlcIi I throw from my hand, and which is deflefted 16 feet in one fecond, the weight of this ftone, if taken up to the height of the moon, fhould be reduced to the 25-:oth part, and fhould there defied jyg^th of l6feet in a fecond; and the moon fhould deflea 47 ASTRONOMY. iefleft as much from ihe tangent in a fecond. Having certain. Wc acknowled'^c ti.at tlie experiments on the dimenfioni!, as he thought, of the moon's orbit, he penduhims, confiftiiig of a vail variety of tcrrcllrial mat- immediately computed the moon's defltdlion in a fe- fer, all of which performed their ofcillations in equal cond ; but he found it confiderably different from what times, demoniirate that tlie acceleration of gravity on he wiflied it to be. He therefore concluded that the thole pendulums w-as proportional to their quautitl-.s of planetary force was not the weight of the planet. For matter, and that equal gravitation may be affirmed of all ibme years he thought no more of it : but one day, in terreftrial matter. the Royal Society, he heard an account read of mea- The elliptical motion of a planet is full proof that furements of a degree of the meridian, which (hewed the accelerating power of its gravity varies in the in- liim that the radius of the earth and the diftance of the verfe dujjlieate ratio of the diliance ; and the propor- moon were very different trom vhat he had believed tionality of the fqnares of the periods to the cubes of them to be. When he went home lie repeated his com- the diftances, fliews that the whole gravitations of the putation, and found, that the deflcdlicn of a ftone was planets vary by the fame law. But this third obferva- to the fimultaneous deflertion of the moon as the fquare tion of Kepler miglit have been the fame, although the of the moon's diftance from the centre of the earth to gravitation of a particle of matter in Jupiter had been the fquare of the ftone's diftance. Therefore the moon equal to that of a particle of terreftrial niatter, provided is defleded by its weight ; :uid the fall of a ftone is juft that all the matter in Jupiter did not gravitate. If a particular inftance of the exertion of the univerfal pla- -s'jth of Jupiter had been fuch gravitating matter, his netarv force. This computation was but roughly made defledion from the tangent of his orbit would have at firll ; but it was this coincidence that excited the been the fame as at prefent, and the time of his revolu- philofopherto a more attentive review of the whole fub- tion would have been what we obferve. In order that jeft. When every circumilance which can affeft the the third law of Kepler may hold true of the planetary refult is taken into account, the coincidence is found to motions, no more is required than that the accumulated le moft accurate. The fall of the Hone is not the full gravitation of the planet be proportional to its quantity effeft of its weight ; for it is diminiftied by the rotation of matter, and thus the matter which docs not gravi- of the earth round its axis : It is alio diminiihcd by the tate will be compenlated by the fuperior gravitation of •weight of the air which it difplaces : It is alfo dimi- the reft. nilhed by its tendency to the moon. On the other But becaufe we have no authority for faying that hand, the moon does not revolve round the earth, but there is matter which gravitates differently from the round a common centre of the earth and moon, and its reft, or which does not gravitate, we are intitled to period is about T-Tcth Shorter than if it revolved round fuppofe that gravity operates alike on all matter. ^g the earth ; and the moon's deflexion is aflfefted by the And this is the ultimatum of the Newtonian ])hiIo. Which h fun's difturbing force. But all thefe correftions can be fophy, that the folar fyftem coniifts of bodies compofed^'^"^ ultima. accurately made, and the ratio of the full weight of the of matter, every particle of which is, in faft, continually "f"^ '/ 'l" ftone to the full defledlion of the moon afcertained. deflefted by its weight toward every other particle in the This has been done. fyftem ; and that this defleftion, or aftual deviation, or Terreftrial gravity therefore, or that power by which aftual preffure, tending to deviation from uniform r^c- bod.'es fall or prcfs on their fupports, is only a particu- tilincal motion, is in the inverfe duplicate ratio of the lar inftance of that general tendency by which the pla- diftance. nets are retained in their orbits. Bodies may be faid to This doftrine has been called f/je fyjlem of univer/n/ Oh]ta grai'itt7te when they give indications of their hiding gra- gravitnt'ton ; and it has been blamed as introducing an'"'h^liivr Ills or heavy, that is, when they fall or prefs on their unphilofophical principle into fcience. 47 The uni- verfal law of graviia- tioii, nig an ' Gravitation is;f^f^["*- fupports ; therefore the planets may be faid to gravi- faid to be an occult quality ; and therefore as unlit foriv,u!,H.j tate when they give fimilar indications of the fame ten- the explanation of phenomena as any of the occult qua- dency by their curvelineal motions. The general fact, lities of Arillotle. But this reproach is inifounded ; that the bodies of the folar fyftem are mutually dclieft- gravitation does not exprefs any q\r.ility whatever, but ed toward each other, may be expreffed by the verbal a matter of faft, an event, an adtual defleclion, or an noun GRAVITATION. Gravitation does not exprefs a aftual preffure, producing an atlual dcfleftion of the quality, but an event, a dcfleftion, or a preffure. body prefted. 'I'hele are not occult, but matters of The weight of a terreftrial body, or its preflure on continual obfervation. True, indeed, Newton does not its fupport, is the eflttl of the accumulated gravitation deny, although he does not pofitively f„y, that this de- of all its particles ; for bodies of every kind of matter fleftion, preffure, or gravitation, is an efl'cdl having a fall equally faft. This has been afcertained with the caufe. Gravity is faid to be this caufe. Gravity is the Btmoft accuracy by Sir Ifaac Newton, by comparing the lelng gravis or heavy, and gravitation is the giving iiicii- vibratioiis of pendulums made of every kind of matter, cations of being heavy. Hiavinefs therefore is the word Therefore their unitedgravitation is proportional to their w Inch expreffes gravitas, and our notion of the caufe of quantity of matter; and we have concluded, that every the planetary defiettions is the fame with our notion of atom of terreftrial matter is heavy, and equally heavy, heavinefs. This may be indiftinft and unfatisfaflory to We extend this conclufion to the fun and planets, and a mind faftidioufly curious; but nothing can be more fay, that the obferved gravitation of a planet is the uni- familiar. The planet is defledled, becaufe it is heavy. ted gravitation of every particle. Therefore Sir Ifaac We are fuppofed to explain the fall of a ftone through Newton inferred, from a collefted v(f w of all the phe- water very fatisfaftorily, and without having recourfe nomena, that all matter gravitates to all matter with a to any occult quality, when we fay that it is heavier force in the inverfe duplicate ratio of the diftance. than the water ; and we explain the rife of a piece of But we do not think that this inference is abfolutely cork, when we f»y that it is not fo heavy as the water. The 48 ASTRONOMY. so Our know ledge of that law Ta tis.'adlory. "Vain at. tempts t'j accoiir.t for it. The explanations of the mutual actions of the phnets are equally fatisfaftory, founded on the fame principles, and equally free from' all fophiftry or employment ot occult caufes. The weight of a body is not its lieavi- nefs, but the effeft of its heavinefs. It is a gravitation, an adual prefTure, indicated by its balancing the fup- pofed heavinefs of another body, or by its balancing the known elafticity of a fpring, or by balancing any other natural power. It is fimilar to the prcffuve wliich a magnet exerts on a piece of iron. This may perhaps be produced by the impulfe of a ftream of fluid ; fo may the weiglit of a heavy body. But we do not con- - cern ourfelves with this queftion. We gain a mod ex- tenfive and important knowledge by our knowledge of "this univcrfal law ; for we can now explain every phe- nomenon, by painting out how it is contained ni this law ; and we can prediA the whole events of the folar fyftem with unerring cxaclnefs. This Ihould fatisfy the moil inqulHtive mind. But, nilimur in I'etitum, fsmper cupjmufque negata. There feems to be a fatal and ruinous dilpoiition in the human mind, a fort of priapifm of the uuderitanding, that is irritated by every interdift of natural imperfec- tion. We would take a microfcope to look at light ; we would kno-M what inoiu'iiig is, and we would ivelsh hea-vinefs. AU'who are acquainted with the writings of Ariftotle have fome notion of his whimfical opinions on this lub- jeft. He imagines that the planets are condufted in their orbits by a fort of intelligences, Stkeo M'i/;\;at, which animate the orbs that wheel them round. Although this crude conception met with no favour in later times, another, not more reafonable, was maintained by Leib- nitz, who called every particle of matter a monad, and gave it a perception of its fituation in the univerfe, of its dillaiice and direction from every other, and a power and will to move itfclf in conformity to this fituation, by certain conllant lavi-s. This irmf ■^rux' hi the Mo- nad is nothing but an aukward fubftitute for the prin- ciple of gravitation, which the learned inlifted that New- ton placed in every particle of matter as an innate power, and which they reprobated as unphilofophical. But in what refpeft this perception and aftive propcn- fity is better, we do not perceive. It is more com- plex, and involves every notion that is reprehenfible in the other; and it offers no better explanation of the phenomena. But Newton is equally anxious with other philofo- phers not to afcribe gravity to matter as an innate in- herent property. In a letter to Dr Bently, he earneft- ]y requefts him not to charge him with fuch an abfurd opinion. It is an avovicd principle, that nothing can ad on any thing that is at a diftance ; and this is confider- ed as an intuitive axiom. But it is furely very obfcure ; for we cannot obtain, or at leaft convey, clear notions of the terms in which it is expreffed. The word aH is entirely figurative, borrowed from animal exertions ; it is therefore unlike the expreflion of any thing intitled to the appellation of inluilive. If we try to exprefs it without figure, we find our confidence in its certainty greatly diminiihed. Should we fay that the condition of a body A cannot depend on another body B that is at diftance from it, we believe that no perf^on will fay that he makes this aflertion from perceiving the abfur- Uity of the contrary propofition. In the deraonftration, as it is called, of the perfeverance of a body in a (late of reft, tlie only argument that is offered is, that no caufe can be alhgned why it fiiould move in one direftion ra- ther than in another; but Ihould any one fay that ano- ther body is near it, to the right hand, and that this is a I'ufBcient reafon for its mo\ing that way, we know no method by which this affcrtion can be ftiewn to be falfe. Such, however, has been the uniform opinion of phi- lofophers. Nihil movclur (fays Leibnitz) nifi a contigiia et molo. The celebrated mathematician Euler having difcovered, as he thouglit, the produdlion of a preflure, like gravity, from motion, fays, " as motion may arife from preffnig powers, fo we have feen that preffing powers may aiifc from motion. We fee that both exill in the univerfe. It is the bufinefs of a philofopher to difcover, by reafon and obfervatioii, which is the origin of the other. It is incompatible with reafon that bo- dies (hould be pofFefTed of inherent tendencies ; much more that powers fliould exill independently. Farther, that philofopher mull be reckoned to have affigned the true caufes of phenomena, who demonftrates that they arife from motion ; for motion, once exiiling, muft be preferved for ever. In the prefent inftince (a certain whimfical fadl of a ball running round the infide of a hoop) we fee how a preffing power may be derived from motion ; but we cannot fee how powers can exert them- fclves, or be preferved, without motion. Wherefore we may conclude that gravity, and all other powers, are derived from motion ; and it is our bufinefs to invefti- gate from what motions of what bodies each obferved power derives Its origin." Accordingly many attempts have been made to trace the planetary detletllons to their origin in the motion of fome impelling matter; but thefe attempts could not be fuccefsful, becaufe they are all built on hypothefes. It has been afiumed, that there Is a matter diffufed through the celeftial fpaces ; that this matter is in mo- tion, and by Its impulfe moves the planets : but the on- ly reafon that can be given for the exiftence of this matter is the difficulty we find In explaining the plane- tary deflections without it. Even if the legitimate con- fequences of this hypothefis were confiftent witTi the phenomena, we have not advanced In our knowledge, nor obtained any explanation. We have only learned, that the appearances are fuch as would have obtained had fuch a matter exifted and adled in this manner. The obferved laws of the phenomena are as extenfive as thofe of the hypothefis ; therefore it teaches us no- thing but what we knew without It. But this Is not all that can be faid agalnft thofe at-inconfifter tempts; their legitimate confequences are mconjjjlent auilh cy v( [oau the phenomena. By legitimate confequences we mean"''""''?' the laws of motion. Thefe muft be admitted, and are j|^^ pheao admitted, by the philofopher who attempts to explain mena. the planetary motions by Impulfe. It would be ridicu- lous to fuppofe a matter to fill the heavens, having laws of Impulfe different from thofe that are obferved by common matter, and which laws muft be contrived fo as to anfwer the purpofe. It would be more fimple at once to affign thofe pro re nata laws to the planets themfelves. Yet fuch was the explanation which the celebrated Defcartes offered by his hypothefis of vortices, in which the planets were immerfed and whirled round the fun. It ASTRONOMY. 53 It is aftonifiiing tliat fo crude a conception ever obtain, net follows its motion, non ahrepta tamcn^ fed trnnqmlli. ITorticfs of pj 3py partifans ; yet it long maintained its authority, ter quuji natante The planet therefore lias no tenden- Defcartcs ^^^j U^jjj ^^^ zealous defenders. Till Sir Ifaac Newton cy to perl'evere in its former date of motion. Why faw the indifpeniable neceffity of mathematical inveftiga- therefore does it not follow this harmonic motion cx- tion in every quellion of matter in motion, no pcrfon aftly, and defcribe a circle tranquilliler nalans ? This is had taken the trouble of giving any thing like a diftincl owing, fays Leibnitz, to its centrifugal force, by which defcription of thofe vortices, the circumftances of their it perfeveres in a ftate of re6lilineal motion. It has no motion, and the manner of their adlion ; all determined tendency to prcferve its former velocity, but it perfe- with that prccilion that is required in the explanation : veres in its former direftion. The planet therefore is for this mull always be kept in mind, that we want an not like common matter, and has laws of motion pccu- explanation of the precile motions luhich have been oh- liar to itfelf ; it was needlefs therefore to employ any ferved, and which will enable us to predict thofe which impulfe to explain its motions. But to proceed : I'his are yet to happen. Men were contented with fome centrifugal force mull be counterafted in every point of vague notion of a fort of fimilarity between the effects the orbit. Leibnitz therefore fuppofes that it is alfo of fuch vortices and the planetary motions in a few ge- urged toward the centre by a folicitation like gravity iieral circumftances ; and were neither at the trouble to or attraiftion. He calls it the paracentric force. He confider how thefe motions were produced, nor how far computes what muft be its intenlity in different parts of they tallied with the phenomena. Their account of things the orbit, in order to produce an elliptical motion, and was only fit for carelefs chat, but unworthy of the at- he finds that it muft be inverfely as the fquare of the tention of a naturalift. But fince this explanation came diftance from the centre (for this reafon he is frequent- 54 from a perfon defervedly very eminent, it was refpefted ly quoted by Bernoulli, Wolff, and others, as the difco- Examined by Newton, and he honoured it with a ferious exami- verer of the law of gravitation). But Leibnitz arrives 3/ Newton, pjfjon^ It is to this examination alone that we are in- at this refult by means of feveral mathematical blunders, debted for all the knowledge that we have of the con- either arifing from his ignorance at that time of fiuxio- flitution of a fluid vortex, of the motions of which it nary geometry, or from his perceiving that an accurate is fufceptible, of the manner in which it can be produ- procedure would lead him to a conclufion which he did ced, the laws of its circulation, and the effeits which it not wifli : for we have feen (and the demonllration vi can produce. We have this account in Sir Ifaac New- adopted by Leibnitz in all his pofterior writings of this ton's Principles of Natural Philofophy ; and it contains kind), that if the ordinary laws of motion are obferved, many very curious and interefting particulars, which a body, aftuated by this paracentric force alone, will have been found of great fervice in other branches of defcribe an ellipfe, performing both its motion of har- mechanical philofophy. But the refult of the examina- monic circulation, and its motion of approach to and re- tion was fatal to the hypothefis ; fhewing that the mo- cefs from the centre, without farther help. Therefore, tions which were pofTible in the vortices, and the effefts if the harmonic circulation is produced by a vortex, a which they muft produce, are quite incompatible with force inverfely as the fquare of the diftance from the the appearances in the heavens. We do not know one centre, combined with the harmonic circulation, will perfon who has acquired any reputation as a mechani- produce a motion entirely different from the elliptical. ciau that now attempts to defend it ; nor do we know It is demonftrated, that the force which is necelfa.y for of any other perfon befides Newton who has attempted defcribing circles at different diftances, with the angu- to explain mathematically how the circulation of a fluid lar velocity of the different parts of the orbit, is not in can produce the revolution of a planet, if we except Mr the inverfe duplicate, but in the inverfe triplicate, ratio j5 Leibnitz, the celebrated rival of the Britilh philofopher. of the diftances. This muft have been the nature of lypothefis This gentleman publifhed in the Leipfic Review in his paracentric force, in order to counteraft the centri- f Leibnitz. 1689, three years after the publication of the Prlncipia, fugal force arifing fiom the harmonic circulation. There 49 5« an attempt to explain the elliptical motion of the *pla- fore Leibnitz has not arrived at his conclufion by juft ty'o'f the"'" nets, and the defcription of areas proportional to the reafoning, nor can be faid to have difcovered it. He author, times, by the impulfe of a vortex. It muft not be paffed fays, Fideo banc propnfa'wnem innotwjfe viro celiberrimo over in this place, becaufe it acquired great authority Ifaaco Ne-ivtono, licet mn pojjim iudictre quomodo ad earn in Germany, and many of that country ftiU affirm that pervenerit. This is really fomewhat like impudence Leibnitz is the difcoverer of the law of planetary gra- The Primipia were publifhed in 16S6. They were re^ vitation, and of the mechanical conftitution of the folar viewed at Leipfic, and the Review publifhed in 1687* fyftem. We cannot help thinking this explanation the Leibnitz was at that time the principal mana.rer of that moft faulty of any, and a moft difingenuous plagiarifm Review. When Newton publifhed, Leibnitz was livins? from the writing^s of Newton. _ at Hanover, and a copy was fent him within two Mr Leibnitz fuppoles a fluid, circulating round the months of its piibhcation, by Nicholas Facio lonT be fun in fuch a manner that the velocity of circulation in fore the Review. The language of the Review has every part is inverfely as its diftance from the fun. feveral fingularities, which are IVequent in Leibnitz's" (N. B. Newton had ftiewn that fuch a circulation was own compofition ; and few doubt of its being his wri pofTible, and that it was the only one which could be ting. Befides, this propofition in the Prmcipia had generated in a fluid by an aflion proceeding from the been given to the Royal Society feveral years before centre). Leibnitz calls this /j«rm«5«i<-rt/ «V™/,7/i»re. He and was in the records before 1684. Thefe were all fuppofes that the planet adopts this circulation in every feen by LeibnitK when in England, belnsj lent him bv part of its elliptical orbit, obeying without any refift- his friend Collins. ^ ance the motion of this fluid. He^does not afcribe this We think that the opinion which a candid rerfon to the impulfe of the fluid, faying exprefsl^ that the pla- muft form of the whole is, that Leibnitz knnv the pro SuppL. Vol.. I. Part !. polition, 50 ASTRO pofition, and attempted to Jemonftrate it in a way that would make it pafs for liis own difcovcry ; or that he only knew the enunciation, without underltanding the principles. His harmonic circulation is a clumfy way of explaining the proportic^nality of areas to the times; and even this circulation is borrowed from Newton's dif- fertation on the Cartelian vortices, which is alfo con- tained in the Leiptic Review above mentioned. Leib- nitz was by this time a competitor with Newton for the honour of inventing the ilnxionary mathematics, and was net giiiltlefs of adts of difmgenuity in afltrtinjj his claini. He publifhed at the fame time, in the fame Re- view, an almoft uniiitelliijible dilfcrtation on the refill- ancc of fluids, which, when ex;imined by one who has learned the fubjaft by reading the Principia of Newton, affords an enigmatical delcription of the very theory publilhed by Newton, as a ncceffary part of his great work. But befides all the above objcftions to Leibnitz's theo- ry of elh'ptical motion, we may alk, What is this paracen- tric force ? He calls it like gravity. This is precifely Newton's doftrine. But Leibnitz fuppofes this alfo to be the impulfe of a fluid. It would have been enough had he explained the aftion of this fluid, without the other circulating harmonically. He defers this expla- nation, however, to another opportunity. It muft have very lingular properties : it muil impel the planet with- out difturbing the other fluid, or being difturbed by it. He alfo defers to another opportunity the explaining how the fquares of the periodic times of different pla- nets are proportional to the cubes of the mean dillances; for this is quite incompatible with the harmonic circu- lation of his vortex. This would make the fquares of the periods proportional to the diftances. He has per- formed neither of thefe promifes. Several years after this he made a correftion of one of his mathematical blunders, by which he deftroyed the whole of his de- monflration. In fliort, the whole is fuch a heap of ob- fcurc, vague, inconfiftent aflumptions, and fo replete with mathematical errors, that it is aftonifliing that he had 57 the ignorance or the effrontery to publifti it. Hypothefis There is another hypothefis that has acquired fome of Le Sage, reputation. M. le Sage of Geneva fuppofes, that there pafles through every point of the uiiivcrfe a ftream of fluid, in every direction, with aftoniniing velocity. He fuppofes that, in the denfeft bodies, the vacuity is in- comparably more bulky than the folid matter ; fo that a folid body fomewhat refembles a piece of wire cage- work. The quantity of fluid which pafles through will be incomparably greater than that of the intercepted fluid ; but the impulfe of the intercepted fluid will be fenfibly proportional to the quantity of folid matter of the body. A Angle body will be equally impelled in every direiSion, and will not be moved ; but another body will intercept fome fluid. Each will intercept fome from the other ; and the impulfe on B, that is in- tercepted by A, will be nearly proportional to the mat- ter in A, and inverfely proportional to the fquare of its didance from B ; and thus the two bodies will ap- pear to tend toward each other by the law of gravita- tion. Tvj'. le Sage publiflied this in a work called Chimie Mech.iniijue, and read lectures on this doftrine for many years in Geneva and Paris to crowded audiences. It is alfo pubhflaed by Mr Prevofl. in the Berlin Memoirs, N O M Y. under the name of Lucrccc Newtonitnt and there ar* many who confider it as a good explanation of gravita- tion : for our part, we think it inconceivable. The inotions of the planets, with undiminiflied velocity, for more than four thoufand years, appears incompatible with the impelling power of this fluid, be its velocity what it will. The abfolute precilion of the law of gra- vitation, which does not fliew the fmallell error during that tiine, is incompatible with an impulfe which cannot be exadly proportional to the quantity of matter, nor to the reciprocal of the fquare uf the diftance, nor the lame on a body moving with the rapidity of the comet of 1680 in its perihelion, as on the planet Saturn, whofe motion is almofl incomparably flower. What is the origin of the motion of this fluid : Wliv does it not deilroy itfclf by mutual impulfe, fmce it is conti- nually palfuig through every point ] Sec. We have already obferved that Newton exprefled thej;,),^^ ^f fame anxiety to avoid the fuppofitlon of aftion among Nfwton bodies at a dillance. He alfo ftemcil to fliow fome dif-'"'^'^*"" pofition to account for gravitation by the action of a * contiguous fluid. This is the fubterfuge fo much re- curred to by precipitate fpeculatilts, by the name of the elhef of Sir Ifaac Neivton. He fuppofes it highly claft:ic, and much rarer in the pores of bodies, and in their vicinity, than at a diiT:ance ; therefore exceedingly rare in the fun, and denfer as we recede from him. Be- ing highly elalT.ic, and repelled by all bodies, it muft impel them to that fide on which it is moft rare ; there- fore it muft impel them toward the fun. This is enough of its general conftitution to enable us to judge of its fitnefs for Newton's purpofe. It is wholly unfit ; for fince it is fluid, unequally denfe and elaftic, its particles are not in contact. Particles that are elattic, and in a ftate of compreffion, and in contaft, cannot be fluid ; they muft be like fo many blown bladders compreffed in a box; therefore they are not in contact; therefore they are elaftic by mutual repulfion ; that is, by afting on each other at a diftance. It is indifferent whether this diftance is a million of miles, or the millionth part of a hair's breadth ; therefore this fluid does not free Newton from the fuppofition which he wifhes to avoid. Nay, it can be dcmonftrated, that in order to form a fluid which fliall vary in denfity from the fun to the extre- mity of the folar fyftem, there muft be a mutual repul- fion extending to thai dijlance. This is introducing mil- lions of millions of the very difficulties which Newtor> wifhed to avoid ; for each particle prefents the fame difficulty with a planet. We would now afl< thefe atomical philofophers, why they have, in all ages, been fo anxious to trace the ce- leftial motions to the cffefts of impulfe ? They imagine that they have a clear perception of the communication of motion by impulfe, while their perception of the pro- duftion of it in any other way is obfcure. Seeing, in a very numerous and familiar collcftion of fafts, that motion is communicated by impulfe, they think that it is communicated in no other way, and that impulfe is the only moving power in nature. -- But is it true that our notion of impulfe is more clear Ournotio than that of gravitation \ Its being more familiar is no°f ""P"^' argument. A caufe may be real, though it has exerted !'|°"'^'' itfelf but once fince the beginning of time. In no cafe vitation. do 1st perceive the exertion of the caule ; we only per- ceive the change of motion. The conftitution of our mind A S T R mind makes us confider tin's as an ciFoft, indicating a caufe which is inherent in that body which we always fee aflbciated with that change. Granting that our per- ception o( the perfeverance of matter in its Hate of mo- tion is intuitive, it by no means follows that the body A in motion muft move the body B by llriking it. The moment it ftrikes B, all the metaphyiical argu- ments for A's continuance in motion arc at an end, and they are not in the lead affeifled by the fiippofition that A and B Ihould continue at reft atttr the ilroke ; and we may defy any perfon to give an argument which will prove that B will be moved; nay, the very exillence of B may, for any thing we know to the contrary, be a fufficient reafon for tlie cefTation of the motion of A. The produftion of motion in B, by the inipulfe of A, mull therefore Hand on the fume foundation with every other produttion of motion. It indicates a moving power in A ; but this inherent power feems to have no dependence on the motion of A : (See what is con- tained in n^Si. of the ai-ticle Physics, and n^ 67. of 0?Tics of the Encyil.) We fee there a motion pro- duced in B without inipulfe, and taken from A, fimilar in every refpccft to every cafe of inipulfe ; and we fee that the motion of A is neceffary for producing fuch a motion in B as is obferved in all cafes of impnlfe. mere- ly in order that the moving power, which is inherent in A, whether it be in rett or in motion, may aft du- ring a fufficient time. Our confidence in the commu- nication ot motion, in the cafe mentioned there, is de- rived entirely from experience, which inl'orms us that A pofleflcs a moving power totally different from im- pulle. Our belief of the impelling power of matter therefore does not neceftarily flow from our intuitive knowledge of the perfeverance of matter, although it gives us the knowledge of this perfeverance. It is like a mathematical demonltration, a road to the difcovery of the property of figure, but not the caufe of that property. The impullion of matter is nn-rely a faft, like its gravitation, and we know no more of the one than of the other. It is not a clearer perception, therefore, which has procured this preference of impulfion as the ultimate explanation of motion, and has given rife to all the fool- i(h hypolhefes of planetary vortices, ethers, animal fpi- rits, nervous fluids, and many other crude contrivances for explaining the abttrufe phenomena of nature. Nor does it dcfcrve any preference on account of its greater familiarity. Juft the contrary ; for one faft of undoubted impulfe, we fee millions where no impulfe is obferved. Confider the motion produced by the cxplo- fion of gunpowder. Where is the original impulfe ? Sup- pofe the impulfe of the firft fpark of fire to be inimenfe, how comes it that a greater impulfe is produced by a greatei- quantity of gunpowder, a greater quantity of quiefcent matter ? The ultimate impulfe on the bullet lliould be lefs on this account. Here are plain exer- tions of moving powers, which are not reducible to im- pulfe. Confider alfo the fafts in animal motion. Re- fleft alfo, that there has been more motion, without any obferved impulfe, produced in the waters of a river fince the beginning of the world, than by all the impulfe that man has ever obferved. Add to thefe, all the motions in magnetifm, eleftricity, &c. Impulfe is therefore a phenomenon which is comparatively rare. Have we ever obferved motion communicated by pure O N O M Y. impulfe, without the aftion of forces at a diftanco ? This appears to us very doubtful. Every one acquaint, ed with Newton's difcoveries in optics will grant, that tlie colours which appear between two objeitglafles of long- iclclcopes, when they are pr'effed together, de- monftrate that the glalfes do not touch each other, ex- cept in the place where there is a black fpot. It re- quires more than athoufaud pounds to produce a fquare inch of this fpot. Therefore every cominunication of moiion betwei.n two pieces of glals, which can be pro- duced by one of them ftriking the other, is produced without impulfe, unlefstheirmutual prcffure has exceeded 1000 pounds on the Iquare inch of the parts which adl on each other. Nay, fince we fee that a black fpot ap- pears on the top ot a foap bubble, in the middle of the coloured rings, we learn that there is a certain thick- iiefs at which light ceafes to be vifibly refltfted ; there- fore the black ipot between the glafles does not prove that they touch in that part ; therefore we cannot fay that any force whatever can make them touch. The ultimate repulfion may be infuperable. If this be the cafe, the production of motion by impulfe is, in every inlfance, like the prodi.ftion of motion between the magnets in n"8l. of the article Physics in the Encycl. 5» and is of the fame kind with the production of motion by gravity. ... 61 Therefore no explanation of gravitation can be de- Intervening rived from any hypothefis whatever jf intervening fluids: fluids mul- They only fubllitute millions of bodies for one, and Hill"''*. '''^" leave the aftion e dijlanli tiie fame difficulty as before. ' It is not in the leait necelfary that we fliall be able to conceive how a particle of matter can be influenced by another at a diflance ; if we have difcovercd in every inilance the precife degree and diredlion of the effeft of this influence, we have made a nioft important addi.. tion to our kiiewledge of nature ; and our fuccefs in the cafe ot the power of gruvity (liould make us aflidu- ous in our endeavours to difcover, from the phenomena, the laws which regulate the other adtions e d'ljlani't, which oblervation is daily finding out. A knowledge equally accurate of the law of magnetic and electric ac- tion may enable us to give theories of magnetifm and eletlricity equally exait with the Newtonian theory of gravitation. Having, we hope, evinced the truth of this theory, by following ou- the inveftigations to which Newton was gradually led, we might proceed to confider, in or- der, the complicated and iubordinate phenomena which depend on it. The lunar and planetary iiicqualitics are the fubjeft s that naturally come firil in our way ; but they have already been explained in all the detail that this concile account -will admit, as they occurred to Newton as tells of tlie truth of his conjecture. If the law be fuch as he fufpedled, its confequenccs niufl be fo and fo; if the celeftial motions do not agree with them, the law nmft be rejefted. We (hall not repeat any thing therefore on this head, but confine our obftrvations to fuch applications of the theory of univerfal gravitation, as newly difcovered objcfts, or the improvement of af- tronomical obfervation and of fluxionary analyfis, have enabled us to make fince the time of Newton. The fubferviency of the eclipfes ot Jupiter's fatel- lites to geography and navigation had occafioned their motions to be very carefully obferved, ever fince thefe ufes of them were firll fuggefted by Galileo, and their G 2 theory 52 ASTRONOMY. 123 61 26 theory is as far ativanced as (hit of the primary planets. It has peculiar difficuhieF. B>;lng very near to Jupiter, the great deviation of his figine from perfett fphericity makes the relation between then- diftances from his centre and their gravitations toward it vaftly complica- ted. But this only excited the mathematicians fo much the more to improve their analyfis; and they faw, in this little fyllem of Jupiter and his attendants, an epi- tome of the iolar n (km, where the great rapidity of the motions mud bring about in a Ihort time every va- riety of configuration or relative pofition, and thus give us an example of thofe mutual diiturbances of the pri- mary planets, which req\nre thoufands of years for the dil'covery of their periods and limits. We have derived g2 fome verv remarkable and uleful pieces of intornation Etertial du-from this inveftigation ; and have been led to the dif- jability uf covery of the eternal durability of the folar fyftem, a fvain'^"^ thing which Newton greatly doubted of. ' "^ Mr Pound had obfcrved long ago, that the irregula- rities of the three interior fatellites were repeated in a period of 4^7 days ; and this obfervation is tound to be juft to this day. 247 revolutions of the firft occupy 437d. 3h. 44' fecond 437 3 42 third 437 3 36 fourth 435 14 16 This naturally led mathematicians to examine their mo- tions, and fee in what manner their relative pofitions or configurations, as they are called, correfponded to this period : and it is found, t!iat the mean langitude of the firft fatellite, tninus thrice the mean longitude of the fe- cond, p/us twice the mean longitude of the third, al- ways made iSo degrees. This requires that the mean motion of the firft, added to twice that of the third, fhall be equal to thrice the mean motion of the fecond. This correfpondence of the mean motions is of itfelf a Angular thing, and the odds againft its probability fcems infinitely great ; and when we add to this the particu- lar pofitions of the fatellites in any one moment, which is necefTaiy for the above conftant relation of their lon- gitudes, the improbability of the coincidence, as a thing quite fortuitous. Becomes infinitely greater. Doubts were firft entertained of the coincidence, becaufe it was not indeed accurate to a fecond. The refult of the in- veftigation is curious. When we follow out the con- fequences of mutual gravitation, we find, that although neither the primitive motions of projeftion, nor the points of the orbit from which the fatellites were pro- jefled, were prccifely fuch as fuited thefe obierved rela- tions of their revolutions and their contemporaneous longitudes ; yet, if they differed from them only by very minute quantities, the mutual gravitations of the fatellites would in time bring them into thofe pofitions, and thofe ftates of mean motion, that would induce the obfcrved relations ; and when they are once induced, thev will be continued for ever. There will indeed be a fmall equation, depending on the degree of unfuit- ablenefs of the firft motions and pofitions ; and this caufes the whole fyftem to ofcillate, as it were, a little, and but a very little way on each fide of this exaft and permanent ftate. The permanency of thefe relations vill not be detlroyed by any fecular equations arifing from external caufes ; fuch as the attion of the fourth fatellite, or of the fun, or of a refifting medium ; be- caufe their mutual afti^n? will diilribute this equatiott as it did the original error. This curious rtfult came into view only by degrees, as analyfis improved and the mathematicians were ena- bled to manage more complicated formulas, including more terms of the infinite lerieies that were employed to exprefs the different quantities. It is to M. de la Grange that we arc indebted for the completion of the difcovcry of the permanency of the fyftem in a ftate very little different from what obtains in any period of its exillence. Although this required all the knowledge and addrefs of this great mathematician, in the manage- ment of the moll complicated analyfis, the evidence of its truth may be perceived by any perfon acquainted with the mere elements of fluxionary geometry. The law of the compofition of forces enables us to exprefs every aftion of the mutual forces of the fun and planets by the fines and cofines of circular arches, which in- ciealc with an uniform motion, like the perpetual lapfa of time. The nature of the circle fhows, that the va- riations of the fines and coiines are proportional to the cofines and fines of the fame arches. The variations of their fquares, cubes, or other powers, are proportional to the fines or cofines of the doubles or triples, or other multiples of the fame arches. Therefore fince the in- finite fericfes which exprefs thofe aflions of forces, and their variations, include only fines and cofines, with their powers and fluxions, it follows, that all accumu- lated forces, and variations of forces, and variations of variations, through infinite orders, are Itill expreflible by- repeated fumsof fines or cofines, correfponding to arch- es which are generated by going round and round the circle. The analyft knows that thefe quantities become alternately pofitive and negative ; and therefore, in whatever way they are compounded by addition of themfelves, or their multiples, or both, we mull always arrive at a period after which they will be repeated with all their iuteiincdiate variations. It may be extremely difficult, it may be impoiTible, in our prefcnt ftate of ma- thematical knowledge, to afcertain all thofe periods. It, has required all the efforts of all the geniufes of Europe to manage the formulas which include terms containing the fourth and fifth powers of the eccentricities of the planetary orbits. Therefore the periods which we have already determined, and the limits to which the inequa- lities expreffed by fecular equations arrive, are ftill fub- jefted to fmaller corrcftions of incomparably longer periods, which arife from the terms neglefted in our formulas. But the correft ion arifing from any negleft- ed term has a period and a limit ; and thus it will hap- pen that the fyftem works itfelf into a ftate of perma.. nency, containing many intervening apparent anomalies. The elliptical motion of the earth contains an anomaly or deviation from uniform circular motion ; the aftion of Jupiter produces a deviation from this elliptical mo- tion, which has a period depending on the configuration of the three bodies; Saturn introduces a deviation from this motion, which has alfo a period ; and fo on. There is another accurate adjuftment of motions which has attrafted attention, as a thing in the higheft degree improbable, in events wholly independent on each other. This is tlie exatl coincidence of the period of the moon's revolution round the earth with that of her rotation round her own axis. The ellipticity or oval fbape of the moon differs fo infeafibly from a fphere, that ASTRO that if the original rotation had differed confidc'rably from the period of revolution, the ])eiidular tendency to the earth could never have operated a change : but if the difference between thofe two motions was fo fmall that the pendular tendency to the line joining the cen- tres of the earth and moon was able to overcome it af- ter fome time, the pole of the lunar fpheroid would de- viate a little from the line joining the earth aiid moon, and then be brought back to it with an accckrated motion ; would pafs it as far on the other fide, and then return again, vibrating perpetually to each fide of N O M Y. 53 tioii of its effedls after a long time. It is only thus that the effeds of the oblate figure (if Jupiter are perceived in the motion of his fatelliles. The boafted found phi- lofophy, which fees fatal necefTity where the mnft fuccefs- fuljludcnts of nature (aw moral excellence, has derived very little credit or title to the name of w//i&?fl, by let- ting loofe all thofe propenfities of the human heart which arc cfltntially deffruftive of focial happiiiefs. Thefe propenfities were always known to lurk in the heart of man ; and thofe furcly were the wifeit who k- ce- the wifl boured to keep them in check by the influence of moral '-^'•'" "f 'lie ^^^ AnH evin- 63 spends 01 e Jaw of metary fledtioii, the mean pofition of the radius veSor. The extent of principles, and particularly by cherifiiing that difpofition Creator. ^ "^ of the human heart which prompts us to fee contrivance wherever we fee nice and refined adjuftment of means to ends ; and, from the admirable beauty of the folar fyftem, to cry out, " Thefe are thy glorious works. Parent of good ! " Almighty, thine this univerfal frame, " Thus woiid'rous fair; thyfelf how wond'rous thenl " Unfpeakahle, who fitt'll above thefe heavens, " To us invifible, or dimly feen " In thefe thy loweil works ; yet thefe declare " -l- hy goodnefs beyond thought, and power divine." Par. Lojt, b. V. " But wandering oft, with brute unconfcious gaze, " Man marks not Thee, marks not the mighty hand " That, ever bufy, wheels the filent fphcres." Thomson. The mod important addition (in a philofophical view) that has been made to aitronomical fcience fines ths difcovery of the aberration of light and the nutation of the earth's axis, is that of the rotation of Saturn's ring. (,- The ring itfelf is an objeft quite Angular; and when "it Satm-iVs was difcovered that all the bodies which had any imme-'''''E- diate connexion with a planet were heavy, or gravita. ted toward that planet, it became an interelling qucf- tion, what was the nature of this ring ? what fupport- ed this immenfe arch of heavy matter without its reft- ing on the planet ; what maintains it in perpetual con- centricity with the body of Saturn, and maintains its furface in one invariable pofition ? The theory of univerfal gravitation tells uj what things are poflible in the folar fyftem ; and our conjec- tures about the nature of this ring muft always be re- gulated by the circumftance of' its gravitation to the planet. Philofophers had at firll fuppofed it to be a luminous atmofphere, thrown out into that form by the great centrifugal force arifing from a rotation ; but its well defined edge, and, in particular, its being two very narrow rings, extremely near each other, yet perfeftly foparate, rendered this opinion of its conftitution more improbable. fg Dr Herfchel's difcovery of brighter fpots on its fur- r'''^" very face, and that thofe fpots were permanent during the""^ '^'' *^'''" whole time of his obfervatlon, fcems to make it more['|,"^'/f'''" probable that the parts of tlie ring have a foliil connec- tion. Mr Herfchel has difcovered, by the help of thofe fpots, that the ring turns round its axis, and that this axis is alfo the axis of Saturn's rotation. The time ' of rotation is loh. 32^. But the other circumllances are not narrated with the precilion fufficient for an ac- tliis vibration would depend 011 the original difference between the motion of rotation and the mean motion of revolution. This difterence muft have been very fmall, becaufe this pendular vibration is not fenfible from the earth. The obferved libration of the moon is pre- cifely what arifes from the inequality of her orbital mo- tion. For the fame reafons, the effefts of the fccular equations of the moon (which would, in the courfe of ages, have brought her whole furface into our view, had her rotation been ftriftly uniform) arc counteracted by her pendular tendency, which has a force fufficient to alter her rotation by nearly the fame flow and iiifenfible changes that obtain in her mean motions. The fame caufes alfo preferve the nodes of her equator and of her orbit in the fame points of the ecliptic. The complete demonftration of this is perhaps the moft delicate and elegant fpecimen that has been given of the modern an- alyfis. We owe it to M. de la Grange : and he makes it appear that the figure of the moon is not that which a fluid fphere would acquire by its gravitation to the earth ; it nm^ W the effeft of a more confiderable el- lipticity, or internal inequality of denfity. This permanency of the fyftem, within very narrov/ limits ot deviation from its prefent ftate, depends entire. ly on the law of planetary deflcftion. Had it been di- redtly or inverfely as the diftance, the deviations would have been fuch as to have quickly rendered it wholly unfit for its prefent purpofes. They would have been very great, had the planetary orbits differed much from circles; nay, had fome of them moved in the oppofite direflion. The feledlion of this law, and this form of the orbits, ftrikes the mind of a Newton, and indeed any heart poffeffed of fenfibility to moral or intellettuaj excellence, as a mark of wildom prompted by benevo- lence. But De la Place and others, infefled with the Tiieophohia Gallicii engendered by our licentious de- fires, are eager to point it out as a mark of fal.difm.. They fry that it is tffential to all qualities that are dif- fufcd from a centre to diminifn in the inverfe duplicate ratio of the diftance. But this is falfe, and very falj'e : it is a mere geometrical conception. We indeid fay, that the denfity of illumination decreafes in this propor- tion ; but who fays that this is a quality ? Whether it be confidcred as the emiffion of luminous corpufcles, or an undulation of an elaltic fluid, it-is not a quality ema- nating from a centre : and even in this eftimation, it feems gratuitous, whether we (hall confider the bafe of the luminous pyramid, or its whole contents, as the ex- preffion of the quantity. Nay, if all qualities muft di- niini(h at this rate, all aftion e J'ljlanti muft do the fame; for when the diftances bear any great proportion to the curate comparifon with the tlieory of gravity. He in- diameters of the panicles, their action deviates infenfibly forms us, that the radii of the four edges of the ring are from this law, and is perceived only by the accumula- 590, 751, 774, 830, of a certain fcale, and that the angle 54 A S T' R O angle fubtended hy the ring at the mean diflance from the earth 1846'". Therefore its eh)ngation is 23 f'. Tiie elon9;:ition of the fecond Cafuiiian fatcUite is 56', and its revolution is. id. I7h. 44'. This (hould give, by the third h*! of Kepler, 1 yh. 10' for the revolution of the outer edge of the ring, or rather of an atom of that edge, in order that it may maintain itfelf i.i equi- librio. The fame c;dculation applied to the outer edge of the inner ring gives about i3h. 36' ; and we obtain Ilh. 16' for tlie inner edge of this ring. Such vane- ties are inconfillent with the permanent appearance of a fpot. We may fuppofe the ring to be a luminous fluid or .-apour, eacli particle of which maintains its lituation by tiie law of pi uietary revolution. In fuch a ilate, it would coniill ot concentric ftrata, revolving more flowly as they were more remote from the planet, like the con- centric ftrata of a vortex, and therefore having a relative motion incompatible with the permanency of any fpot. Befides, the rotation obfervcd by Herfchel is too rapid even for the innermoft part of the ring. We think therefore that it confifts of cohering matter, and of con- fiderable tenacity, at leaft equal to that of a very clam- my fluid, fuch as melted glafs. We can tell the figure which a fluid ring muft have, fo that it may maintain its form by the mutual gravita- tion of its particles to each other, and their gravitation to the planet. Suppofe it cut by a meridian. It may be in equilibrio i; the feftion is an ellipfe, of which the longer avis is direfted to the centre of the planet, and very fmall in comparifon with its dillance from the centre of the planet, and having the revolution of its middle round Saiurn, fuch as agrees with the Keplerean law. Thef . circumftances are not very confiftcnt with the dinienfions of Saturn's inner ring. The diftance between the middle of its breadth and the centre of Sa- turn is 070, and its breadth is 161', nearly one-fourth of the diftance from the centre of Saturn. De la Place fays, that the revolution of the inner ring obferved by Herfchel is very nearly that required by Kepler's law : but we cannot fee the grounds of this affertion. The above comparifuns with the fecond CafTinian fatellite (hows the contrary. The elongation of that fatellite is taken from Bradley's obfervations, as is alfo its periodic time. A ring of detathed particles revolving in loh. 32j' muft be of much fmaller diameter than even the in- ner edge of Saturn's ring. Indeed the quantity of mat- ter in it might be fuch as to increafe the gravitation confiderably ; but this would be feen by its difturbing t_ the feventh and fixth fatellites, which are exceedingly Its proSa- near it. We cannot help thinking therefore that it con- ble conDft- f,(ls of matter which has very conhderable tenacity. An "^"^y equatoiial zone of matter, tenacious like melted glais, and whirled bnfkly round, might be thrown off, and, retaining its great velocity, would ftrctch out while whirling, enlarging in diameter and diminilhing in thick- jiefs or breadth, or both, till the centrifugal force was balanced by the united force of gravit)' and tenacity. We find that the equilibrium will not be fenfibly difturb- ed by confiderable deviations, fuch as unequal breadth, or even want of flatnefs. Such inequalities appear on this ring at the time of its difparition, when its edge is turned to the fun or to us. The appearances of its different fides are then confiderably different. Such a ring or rings muft have an ofcillatory motion round the centre of Saturn, in confcquence of their mu- N O M Y. tual aftion, and the aclion of the fun, and their own ir- regularities : but there will be a certain pofilion which they have a tendency to maintain, and to which they 1 will be brought back, after deviatnig from it, by the ellipticily of Saturn, which is very great. The fun will occafion a nutation of Saturn's axis and a precef- fion of his e<;uinoxes, and this will drag along with u both the rings and the neighbouring fatellites. The atmolphcre which iurrounds a whirling planet cannot have all its parts circulating according to the third law of Kepler. The mutual attrition of the pla- net, and of the different ftrata, arifing from their diffe- rent velocities, muft accelerate the ilowly moving ftrata, and retard the rapid, till all acquire a velocity propor- tional to their diftance from the axis of rotation ; and this will be fuch that the momentum of rotation of the planet and its atmofphere remains always the fame. It will fwell out at the equator, and fink at the poles, till the centrifugal force at the equator balances the weight of a luperficial particle. - The greateft ratio which the equatorial diameter can acquire to the polar axis is that of four to three, unlefs a cohefive force keeps the par., tides united, fo that it conftitutes a liquid, and not an elaftlc fluid like air ; and an elaftic fluid cannot form. an atmofphere bounded in its dimenfions, unlefs there be a certain rarity which takes away all elafticity. If the equator fwells beyond the dimenilon which makes the gravitation balance the centrifugal force, it muft imme- diately diffipate. If we fuppofe that the atmofphere has extended to this limit, and then condenfes by cold, or any chemical or other caufe different from gravity, its rotation ne- ceffarily augments, preferring its former momentum, and the limit wdl approach the axis ; b^caufe a greater velo- city produces a greater centrifugal force, and requires a gg greater gi'avitation to balance it. Such an atmofphere And origi may therefore defert, in fucceffion, zones of its own mat- ter in the plane of its equator, and leave them revol- ving in the form of rings. It is not unlikely that the rings of Saturn may have been furnilhed in this very way; and the zones having acquired a common velocity in their different ftrata, will preferve it ; and they are fufceptible of irregularities arifing from local caufes at the time of their leparation, which may afford perma- nent fpots. We think that the rotation of Saturn's ring affords it mayfi fome hopes of deciding a very important queftion about nidi the the nature of light. If light be the propagation of'"'^*"5°' elaftic undulations, its velocity depends entirely on the , °^"^' 1 n • • 11 I- r 1 n ■ 1 I • r • . . . , t! .e iiatm , elafticity and deniity oi the fluid : but if it be the emif- ^f hght. ,, fion of corpulclcs, their velocity may be affefted by other caules. The velocity of Saturn'^ ring is y| of that of the earth in its orbit, and therefore about To4trs' of the velocity of light. The weftern extremity (to us in the northern regions) is moving from us, and the eaftern is moving toward us. If light, by which we fee it, be reflefted like an elaftic ball from an elaftic body, there will be an excefs in the velocity of the light by which we fee the eaftern limb above the velocity of the light by which we fee the weftern limb. This txctfs will be ^Yss of the mean velocity of light. This fliould be difcovered by a difference in the refraftion of the two lights. If an acromatic prifm could be made to re- fraft fourteen degrees, and if Saturn be viewed through a telefcope with this prifm placed before it, there ftiould be IM. AlIC \ I , ASTRO be a cliange of (liape amounting to fixteen ftconds ; if the axis of the prifm be parallel to the longer axis of the ring, it will diltort it prodigioufly, and give it an oblique pofition. A finnilar effeft will be produced by placing the prifm between the eye-glafs and the image in the focus of the objeAglafs. Our expeftation is founded on this unquefllonable principle in dyn:imics, that when a particle of light pafles through the ailive ftratum of a tvanfparent body which refrads light toward the perpendicular, the addi- tion made to the fquare of its velocity by the refraft- ing forces is equal to the fquare of the velocity which thofe forces would communicate to a particle at rei'l on the furface of this refrafting ilratum of the tranfparent body. Therefore if the velocity of the incident light be increafed, the ratio of the fine of incidence to the fine of refraftion will be diminidied. It is confonant to common fenfe, that when the incident light has a great- er velocity, it pafles more rapidly through the attradling ilratum, and a fmaller addition is made to the velocity. When the velocity of the incident light is loooo times greater than that of the earth's annual motion, the. fine of incidence is to the fine of refrattion in glafs as 20 to 31, or as 10000 to 15500. If this be increafed tt'uoj making it 10004, the ratio will be that of 10004 'o I550>,62, or of loooo to 15496,4. The difference between the refraftions of the light from the eaftcrn and weftern extremities of the ring will be, to all fenfe, the fame, if the velocity of the one be diminifhed to 9998, and the other increafed to tooo2. We may juft add here, by the way, that the aftion of another body may confiderably change the conftitu- obable tion of this atmolphere. Thus, iuppofing that the ifon why moon had originally an atmofphere, the limit v/ill be ; fee no f]^^i diiVance from the moon where the centrifugal force, .. ,u„ arifinsj from the moon's rotation, added to the eravita- jut the . o , , , 1 • ■ , ° ,on, tion to the earth, balances the gravitation to the moon. If the moon be -j-'j-'l^ o'" "^'^^ earth, this limit will be about -^th of the moon's diftance from the earth. If at this diilance the clailicity of the atmofphere is not annihilated by its rarefaction, it will be all taken off by the earth, and accumulate round it. This may be the reafon why we fee no atmofphere about the moon. What has been faid in the article Tide (EncycL), will explain the trade-winds on the earth and in Jupi- ter and Saturn. On the earth they are increafed by the expanfion of the air by heat. This caufea it to rife N O M Y. 55 in the parts warmed by the fun, and flow ofi" tovvaid the poles, where it is again cooled and condenfed. The under ftratum of colder and dcnfer air is continually flowing in from the poles. Tliia having lefs velocity of circulation than the equatorial parts of the earth, mufl have a relative motion cuntrary to that of the earth, or from call to well, and this nuili augment the cuiTent produced by gravitation. Thus we fee that all the mechanical phenomena of the folar fyftcm, whether relating to the revolutions round the various centres of gravitation, or to the figure of the planets and the ofcillations of the fluids which cover them, or to the rotations round their rcf)iei5live axes — are neceffary confequeiices of one limple principle of a gravitation in every particle, decreafing in the re- 71 ciprocal duplicate ratio of the diftance. We fee that AH the me- tliis, combined with a primitive projection, will produce '^?^""^^ every motion tliat we obferve. It was not neccllary, asjja of the Copernicus imagined, to imprefs three motions on the fclav i'yf- eartli : one, by which it was made to revolve round the"^™ fl°*^ fun ; a fecond, caufing it to turn round an axis inclined?.™"', °"'^„ to that ot Its orbit ; and a third, by which this axis de-^ipie, fcribed that conic furface which forms the preceffion of the equinoxes. One iinpulfe, not pafling through the centre of the earth, nor in the plane of the ecliptic, will produce the two firll motions, and the protuberant mat- ter produced by the rotation will generate the third motion, by the tendency of its parts to the other hea- venly bodies. Without this principle, the elliptic mo- tion of the planets and comets, tluir various inequali- ties, fecular or periodical, thofe of the moon and of the fatellites of Jupiter, the prectfTion of the equinoxes, the nutation of the earth's axis, the figure of the earth, the undulations of its ocean — all would have been imperfedl- ly known, as matters of fa£l, wholly different from each other, and folitary and unconnetted. It is truly de- ferving admiration, that fuch an immenfe variety of im- portant phenomena flow fo palpably from one principla, of fuch fimplicity, and fuch univeriality, that no pheno- menon is now left out unexplained, and predifted with a certainty almoft equal to adtual obfervation. Sluit tot'ies animos •ueterum torjerc Jophorum, ■ ^uxque Jcholas hodie rauco certamine vexatit, Ohvia confpiciinus, nubem peUenle Malheft. Surglte mortales, terrenas mlltite euros, jiique hhtc culigenit -u'lres iHgnofi ile mentis, yl pecudum luLi /otige laleque remotte. »^^"5«S®iV^'s!Vvv^•i AST \ ftrothe- ASTROTHEMATA, the places or pofitions of the ftars, in an aftrological fcheme of the heavens. ASTROTHESIA, is nfed by fome for a conftella- tion or coUeftion of ftars in the heavens. ASTRUM, or Astron, a conftellation or affem- blage of ftars : in which fenfe it is diftinguifhed from yfjier, which denotes a fingle ftar. Some apply the term, in a more particular fenfe, to the Great Dog, or rather to the large bright ftar in his mouth. ASYMMETRY, the want of proportion, otherwife A S Y called incommenfuralility, or the relation of two quanti- Afymp. ties which have no common meafure, as between i and '<""• »/z, or the fide and diagonal of a fquare. « ASYMPTOTES (fee Encyd.) v,re, by fome, di- ftinguifiied into various orders. The afymptote is faid to be of the firft order, when it coincides with the bafe of the curvilinear figure ; of the fecond order, when it is a right line parallel to the bafe ; of the third order, when it is a right line oblique to the bafe; of the fourth order, when it is the common parabola, having its axia A U T t 56 ] A U T Attar axis perpendicular to the bafe ; and, in general, of the ^. J! + 2 order, when it is a parabola wliofc ordinate is al- ;'j;^'''f'"3"°' ways as the n power of the bafe. The afymptote is ob- lique to the bafe, when the ratio of the iiril fluxion of the ordinate to tlie fluxion of the bafe approaches to an allignable ratio, as its-limit ; but it is parallel to the Ijafe, or coincides with ii, when this limit is not affign- tible. • ATTAR OF ROSES. See Rosf.s, Otter of, both in the Eiicyclopsdia aivd in this Supplement. AVANT Foss, or lYitch of ihc Counterfcarp, in for- tification, is a wet ditch furrounding the counterlcarp on the outer fide, next to the country, at the foot of the glacis. It would not be proper to have fuch a ditch if it could be laid dry, as it would then ferve as a lodgment for the enemy. AUBIGNE. See Stuart in this Supplement. AUMIL, in Bengal, a native collector or manager of a diftriel on the part of government. AUTENK^A, a large and beautiful country in Africa, lyuig to the eaft of the Cape of Good Hope, and inhabited, part of it, by Dutch colonifts. The word /lutentqua fignifies, in the Hottentot language, «' a man loaded with honey :" a name which is not improperly given to the country, iince, as you enter it •from the Cape, you cannot proceed a flep without iee- ing a thoufand fwarms of bees. The flowers on which they feed fpring up in myriads ; and your attention is engaged, and your courle fufpended, by the mixed odours which exhale from them, by their colours and variety, and by the pure cool air which you breathe. Nature has made thefe enchanting regions like fairy land. The calyxes of all the flowers abound with ex- cellent juices, from which the bees extraft the honey that they everywhere depofite in hollow rocks and trees. This counti-y was viiited in 1782 by M. Vaillant, •who calls it the moft delightful region in the univerfe ; and fays, that, as he approached it, he beheld, from the top of a very high mountain, an immenfe valley, adorn, ed with agreeable hills, variegated in an infinite num- ber of fliapes, and extending in an undulating manner as far as the fea ; whilfl. enamelled meads, and the molt beautiful pafturcs, ftill added to the magnificent fcene. It abounds with fmall rivulets, which, flowing down from the mountains, run into the fea through an hun- dred different channels. The water of thefe rivirlets has the colour of Madeira wine, and a ferruginous tatte ; but our traveller did not examine whether this tafl;e and colour proceed from their flowing through fome mine in their paffage, or from the roots and leaves of trees which they carry along with them. The whole of Auteniqua, from the chain of moun- tains which divides it from the country of that race of Hottentots called Gonaquas to the fea, is inhabited by feveral planters, who rear a number of cattle, make but- ter, cut down timber, and colleft honey ; all of which they tranfport to the Cape : but it appears that they make not the moft of their fituation. •' Can it be be- lieved (fays M. Vaillant), that the diueftors of the Com- pany, for their own ufe, fliould order fliips to be fent every year fi-om Amft;erdam, loaded with planks and boards of every kind, whilfl; in this country there are immenfe forefts, and the mofl: beautiful trees in the world ? This abfurdity, however, is not at all aftonifh- ing. The Company gratuitoufly furnifties the gover- nor and all the officers with whatever wood they have Auteniqu occalion for ; and it is delivered to them at their houfes ~~v~-" without any expence. The governor therefore has no pt:rfanal iiileixll to extend his views to this part of the adminilliation, and to «bolifli an abufe fo prejudicial to the colony." But tlie coloniflis themfelves mull be a very indolent and ilupid kind of people ; fmce, if our traveller de- fcrves credit, they neglec\ advantages with which the perional interell of the governor cannot polfibly inter- fere. '■ I was filled with indignation (lays M. Vail- lant) to fee people, who have wood within their reach, employ it in commerce, and not have the courage to build for themfelves habitable houies. They live in wretched hovels, conilrufted of wicker-work, daul'cd over with clay ; the ikin of a buffalo, fixed at the tour corners to as many flakes, ferves them for a bed ; and the door, which is at the fame time a window, is fliut by a mat ; while two or three mutilated chairs, a few pieces of plank, a kind of table, and a pitiful box of two feet fquare, form all the furniture of thefe colonial habitations. Thus is the pifture of the moft profound mifery contrafted with the charms of this terreftrial pa- radiie ; for the beauties of thefe regions extend even beyond Auteniqua. The people, however, though their houies be bad, live well. They have game and falt-water fifli in abundance ; and enjoy exclufively, over all the other cantons of ihefe colonies, the advantage of having, for the whole year without interruption, ve- getables of every kind in their gardens. For this they are indebted to the excellence of the foil, and to its be- ing naturally watered by fmall llreams, which crofs each other in a thouland different directions, and, as one may fay, lay the four feafons under contribution to fer- tilize Auteniqua. Thefe ftrcams, which frequently over- flow their banks, but never dry up, proceed from a caufe well known; the high mountains towards the eaft, which are covered with foieils, flop tlie clouds and the fogs carried from the fea, and this occafions very abundant rains." In thefe mountainous regions, which, as well as the plain, our author comprehends under the denomination of ^luteniqua, there are multitudes of elephants, buffa- loes, panthers, hyenas, and antelopes of every fpecies ; and all thefe animals are hunted and killed by the na- tives, as well for food as for the proteftion of their flocks and herds from fuch of them as are beafts of prey. Our author has eaten the flefti of every one of them except the hyena ; and declares, that the foot of an elephant, baked after the Hottentot manner, is one of the moft delicious morfels that he ever tafted. He gives dircdlions for hunting them all ; but warns his readers from attacking elephants when he finds them in droves, for then, he fayb, they are invincible. He even thinks it exceedingly dangerous for one man, however well armed, to attack a fingle elephant in the plain. The buffalo he defcribes, contrary to moft other travel- lers, as a timid animal, which never refills till his fitua- tion becomes defperate; and he thinks that there would be no difficulty in training him, if caught when a calf, to the yoke like the bullocks of Europe. The-kites and vultures of this country, our traveller repreients as in the higheft degree voracious and ficrce,in- fomuch that it is hardly pofllble to fright them from their prey. He had on one occafion killed two buifaloes, which A U T . [ 5 . which he ordered to be cut into very finall pieces, that they might be more eafily ialted, and expofed after- wards to the air and the fun. His wagons, as well as the buflies and trees which iurroimdcd him and his peo- ple, were loaded with tlso bloody fragments of thefe two aniinals, and they had begun their operation of falling ; but tn a fudden, while they were not expecting it, they found themfelves attacked by flights of kites and vultures, which, without exliibitlng the lead fymptoms of fear, perched in the midft of them. The kites were above all the moft impudent. They feized upon the morlels of flefh, and even contended furioufly with his people. " When they had each carritd away (fays he) a pretty large piece, they retired to fome branch, at the dillance often paces from us, and devoured it before our eyes. Though we tired our fufees they were not frightened, but returned inceflantly to the charge ; fo that finding our powder walled in vain, we refolved to keep them off with large poles until our provifioiis ihould be quite dry. This manoeuvre, which for a long time haralTed my people, did not prevent us from being plundered without mercy ; but had we not em- ployed it, nothing would have remained to us of our two buffaloes." This battle with the kites took place on the conliues of the Dutch fettlements ; but when M. Vailiant had with difficulty pafTed over the mountains which bound them, the profpefts became more magnificent, the foil feemed to be more fruitful and rich, nature appeared to be more majefllc and grand, and the lofty mountains prefented on all fides more charming and deliglitful points of view than any that he had ever before met with. Thefe fcenes, contrafted with the dry and parch- ed fields of the Cape, made him exclaim, he fays, in ecifacy,"" What! fiiall thefe fuperb regions be eternally inhabited by tigers and lions ? What fpeculator, with the fordid view only of eftablifhlng a kind of centre for commerce, could have preferred the flormy Table Bay to the numberlefs roads and commodious harbours which are to be found on the eaflern coafls of Africa ? Thus (continues he) was I reflefting within myfelf, whilft I was climbing the mountain, and forming vain wKhes for the conqueft of this beautiful couutiy, which the indo- lent policy of the European nations will perhaps never gratify." If his defcription of its beauties and fertility be not greatly exaggerated, it is indeed wonderful that either the Dutch or fo'me other maritime power of Europe has not long ago taken poffeffion of it. After he had paffed the mountain, one could not, he fays, clioofe a more agreeable or advantageous fpot than that upon which he then was for eftablifning a thriving colony. The fea advances through an opening of about a thoufand paces in breadth, and penetrates into the country to the di- ftance of more than two leagues and a half. The bafon which it forms is more than a league in extent (he does not fay whether in breadth or in circumference) ; and the whole coall, both on the right and the left, is bordered with rocks, which intercept all communication with it. The land is watered by limpid and refrefhing ftreams, which flow down on all fides from the eaftern mountains ; and thefe mountains, crowned with majef- tic woods, extending as far as the bafon, and winding round it with a number of linuofities, exhibit a hun- SuppL. Vol. I. Part I. 7 ] A U T dred groves, wliich are naturally variegated, and each Autctiiqua. more agreeable than another. • The author proceeding forwards about two days journey, arrived at a bay known to navigators by the name of the Bay of /i'^oa, but called by the colonifls Blettenlerg's Bay, from its having been viljted fome time before by a Governor Blettenbcrg, who ordered his name, together with the year and day of his arrival, to be engraven on a flone column. This bay is a little beyond the limits of the country called Autenfqua; but it is not foreign from the purpofe of this article to in- fert in this place our traveller's account of it, and of the country around it. The bay itfelf, he fays, is very fpaeious, and has a fufficient depth of water for the largeft vefTels. The anchoring ground is fuie, and boats can fail to a beau- tiful part of the fliore, which is not confined by the rocks, as they are all there detached from one another. By advancing a league along the coaft, the crews would arrive at the moutti of a confiderable river called the ^levr-Boom, where they would find water. Refrerti- ments might be procured from- the inhabitants of tiie environs ; and the bay would fupply them with excel' lent fifh, with which it abounds. This bay is one of thofe places where government might eftablifh warehoufes and repohttn'ies for timber ; and it is for this reafon that we have introduced it to notice in this article. The foret^s around it, fays M. Vailiant, are everywhere magnificent, and the trees could be more eafily cut down than anywhere elfe ; for it is not to fteep mountains that one muft go for wood, as it Auteniqua ; it is here ready at hand ; and during the fine monfoon might be traniported to the Cape with little trouble and no rifk. The inexhauflible and fer- tile lands in the neighbourhood of the bay, if once cul- tivated, would produce abundant crops, and draw toge- ther a great number of intelligent planters, on account of the ready communication which they would have with the Cape. In a word, the Company, continues he, have nothing to do fo much for their own Intereft as to form here a proper ef}ablifliment. To the general profits of fuch an inlHtution, would be added thofe of individuals, which could not fall to be of great import- ance. They might, for example, cut down a certain tree called Jlinking luood, and export it to Europe, where it would undoubtedly be foon preferred to maho- gany and every other kind of wood employed by cabi- net makers. The Hottentots, who in fcattered Iraah inhabit this delightful country, our author defcribes as a faithful, gentle, and rather timid race. He afSrms that they have no religious impreffions whatever, nor any notion of fuperior powers who govern the world. But this, if not a wilful fallehood diftated by the philofophy of France, is probably a miitake arifing from his fcanty knowledge of their language, and total ignorance of the meaning of their religious ceremonies. His great ma- fter, as well as the maffer of his fedl, Lucretius, tnight have taught him, that fear, if not a better principle, will generate the notion of fuperior beings in the minds of favages ; and from fear, by his own account, the inha- bitants of Auteniqua are far from being free. He like- wife affirms, and feems to confider it as much to their credit, tliat this race of gentle beings, fo far from being H a A U T [ 5S ] A X r a prey to the paflion of jealoufy (as other travellers have reprcfenttd the Hottentots in general), are fo cbli- ging, as to lend their wives to travellers who viiit tlicm, and that they actually accommodated his Hottentots in this way. Auteniqua, as laid down in M. Vaillant's map, lies between 33' 30' and 34*^ 5c' of fouth latitude, and between 20'' ?.nd ly 40' of eall lon^'tude ; and his rout through the country was from louth-wtll to north-eaft, or nearly lo. AUTOMATON. U'uler this title and that of AndroidEs full credit was allowed in the Encyc'optdia Bnlanmca to the ftory of M. de Kempel's mechanical chtfs-flaytr, and a detail :it fome length was given of the feats of that figure, as well as of fome other furjjri- iing avtoninln. No man more readily admits the powers of the flvilfnl mechanician than the writer of this lliort article ; but having many years ago detefled the inipo- fition which was pvaftifed on the public in fome parts of Scotland by a circumforaneous mountebank, who exhibited a figure apparently capable of writing a cer- tain number of words, he has ever fmce fufpected im- pofture in all automata which appear to have the power of varying their motions according to circumflances. With refpeft to the chifs-player, there is now fuflicient evidence that his fufpicions were well founded. In the defcription of this figure {Encycl. Vol. I. p. 787.), " it is faid that the automaton could not play unlefs M. de Kempel or his fubrtitute was near it to direct its moves. A fmall box during the game was frequently confulted by the exhibiter ; and herein con- fided the fecret, which he faid he could in a moment communicate." The fecret was indeed fimple : " A well taught boy, very thin and fmall of his age, was concealed in this box almnit immediately under the chefs-board, and agitated the whole machine." This we learn from Thomas Colhnfon, Efq; who was let in- Axie. to the fecret ct Drefdia by a gentleman of rank and ta- Au(n»ia- lents, named 'Jofeph Fre'ulrick Fieyhere, by whom the ""'> •vknlilv and foul of the chefs-playing figure had fome , time before been completely difcovcred. Mr CoUinfon, finding that Dr Hutton had given the fame credit with us to the reality of mechanicdl cliefs-playing, undecei- ved his friend, by communicating the difcovcry of Frey- here in a letter, which the Doctor has with great pro- priety publilhed in the Addend,i to his Mathematical Dictionary, Mr Collinfon adds, and we doubt not with trutii, that, " even after this abatement of its be- ing ilri£tly an automaton, much ingenuity remains to the contriver." This was in fome degree true of the inechanifm of the writing figure, of which the compiler of this article detected the bungling impofture of the two exhibiters. The figure itfclf, with all the principles of its motion, were very ingenioully conflrufted ; but the two men who exhibited it were ignorant and awk- ward, and could not conceal from a fcrutini/ing eye, that the automaton wrote foinetimes well and fometimes ill, and never wrote at all when they were both prefect to the company. It was by infilling upon feeing them both together, and threatening to expole the cheat to the whole town, that the prefent writer prevailed upon him who appeared to be the principal exhibiter, to con- fefs in private that his companion was concealed be- hind a fcreen, and to (how how, from thence, he direct- ed the movements of the figure. Conjugate AXIS, or Second Axis, in the ellipfc and hyperbola, is the diameter paffing through the cen- tre, and perpendicular to the tranfverfe axis ; and is the ftiorteil of all the conjugate diameters. Trunfverfe yfxis, in the ellipfe and hyperbola, is the diameter paffing through the two foci and the two prin- cipal vertices of the figure. In the hyperbola it is the fliorteft diameter, but in the ellipfe it is the longeft. B. Bahrc't. "DAHRDT (Dr Carl Friedirich) was fo deeply con- -_y^_ O cerned in a combination of philofophers formed, as they faid, for the advancement of fcience and virtue, that an account of his life muft be interefling, if it were only to fhow the effe£ts of this philofophic culture on liis own morals. We truil therefore that our readers will be pleafed, perhaps improved, by the following nar- rative, taken from documents the moll authentic, by a man* whofe communications on other fubjefts do cre- dit to this volume. Carl Friedirich Bahrdt was, in 1741, born at Leip- fig, where his father, then a parifh minifter, and after- wards profeflbr of theology, died in 1775. It is natu- ral to fuppofe that fuch a parent would be at due pains to inftil into the mind of his fon the principles of piety, virtue, and patriotifm, which is indeed a branch of vir- tue ; but if fo, he lived to fee that his labour had been « Set Pro- feffor Rt*i- ibn of Edin- burgh's Pmiifs of a Can/piracy egatnji all the Rtligicns and Govern ments oj £u- in vain. While yet at college, where the courfe of his {Indies was calculated to fit him for the important of- * fice of preaching the gofpel, the young man enlifted as a hufiar in the Prufiian fervice ; but being bought off, he returned to the univerfity, where, in I 76 1, he was admitted to the degree of M. A. Soon afterwards he became catechift in his father's church, was a popular preacher, and in 1765 publifhed fermons, and fome controverfial writings, which evinced that he pofTeiTed both learning and genius. Neither learning nor genius, however, nor both united, could attach him to the caufe of virtue, or make him obferve even the common rules of decorum ; for immediately after this publica- tion he began to indulge in conviviality, and to give fcope to his refentments in anonymous pafquinades, in the higheft degree bitter and ofTenfive. From the fiiafta of his malice no perfon was fafe. ProfefTors, magiftrates, and- Eahrclt. BAH Baliriit. atiJ clfrgyman, had indeed his chief notice "—v-"-" coudefcendcd occafionally to attack ftudents, and fpared npt even his own comrades or his friends. Whilil he was thus labouring to make enemies of all to whom he was known, unfortunately, for his own cha- racter, his temperament was what the atomical philofo- phers (who can explain every thing by ethers and vi- brations) call fanguine ; and he was, as he himfelf ac- knowledged, a paffionate admirer of the ladies. Coming home from his midnight revels, he frequently met in his way a young girl neatly drefTed in a rofe-coloured filk jacket and train, and a coftly fable bonnet ; and one evening, after having, as he fays, indulged freely in fome old Rhenifh, he faw her home to her lodgings. Some time after this interview, the miftrefs of the houfe (a Madam Godfchuflvy) came into his room, and faid that the poor maiden whom he had debauched was preg- rant. This was a misfortune tuhich he could not help ; but as it would ruin his charafter if known, he gave to the old lady a bond for 200 dahlers (about L.40 iler- ling), to be paid by inftalments of twenty-five, to keep the matter fecret. " The girl (he fays) was ft ii/i6/e Sind good; and as her converfation, for which he had al- ready paid, was agreeable, he did not difcontinue his acquaintance." It could not be fuppofed that fuch vifits, by a cler- gyman, would pafs unobferved, however cautioufly made, in the midfl of a town, of which the inhabitants had been the indifcriminate objefts of his fatire ; and he could hardly be furprifed when told by a friend, that one Bel, a magiftrate whom he had lampooned, was accquainted with the whole affair, and would bring it in- to a court of juftice, unlefs the bond was immediately retired. This bond was the only evidence which could be pro- duced againft Bahrdt, but it was fufficient to blaft his character in Leipl'g, and muft therefore by any means be removed out of the way. To accomplilTi this, how- ever, was a matter of fome difficulty ; for neither he nor his friend could raife the money. In this dilemma they fell upon a contrivance worthy of themfelves. They invited Madam Godfchu(ky to meet them in another houfe to receive the 200 dahlers due to her by Bahrdt ; but when (he was udiered into the room, and found no perfon waiting for her but Bahrdt's friend, (he could not be prevailed upon to produce the bond till the mo- ney fliould be put into her hands, together with a pre- fent to herfelf. The Gentleman tried to intimidate her. He drew his fword ; fhowed her how men fence ; made pufhes at the wall and then at her : but finding that flie could not be frightened out of her fenfes, he threw avvai' his fword, and endeavoured to take the bond from her by force. It was fome time before he prevailed ; but at laft getting the paper out of her pocket, he tore it in pieces, opened the door of a clofet in which Bahrdt was concealed, and laid, " There, you b ; theie is the honourable fellow whom you and your whore have bullied ; but it is with me you have now to do, and you know that I can bring you to the gallows." Bahrdt, from whole memoirs of himfelf this flory is taken, admits that there was a great fquabble on the occafion ; but he went home, comforting himfelf with the belief that he (liould now have no farther trouble from Madam Godfchu(l a fpawn of the fecrct fociety of ////.'mina/i (fee Illu- MiNATi in this Supplement) ; and tliat its objeft is to abolilli the religion of the gofpel, and to teach in its ftead the fatalifm of the Stoics. With this view Chri- ftiaiu'ty is conlidered in the union as a myftical fociety, and its Divine Founder as the grand mailer of a lodge I The apoftles Peter, James, John, and Andrew, were the ELECT, brethren of the /Air^/ degree, and initiated into all the myfleries. The remaining apoftles were only of thefecond degri;e ; and the feventy-two, of ihejirjl : a degree into which ordinary Chriftians may be admitted, and prepared for farther advancement. The great my- ftery is, that J C was a naturalist, and taught the dotlrine of a fupreme mind, the fpcftator but not the governor of the world. To propagate thefe impious and abfurd notions, Bahrdt publilhed many books of the moit antichriltian tendency, and fome of them calculated to make their readers fhake off all moral obligation. But the labours ot the fociety were not confined to religion : it incul- cated on Its members the moft dangerous maxims of ci- vil conduft : for, as we learn from Bahrdt lilmfelf, the objefts at which the Union aimed were — Advancement ofjcience — a general Interejl and concern for arts and learn- 'ng— excitement of tidents — check of fcribhling—good edu- cation LIBERTY EQJJALITY — hofp'llaliiy DELIVERY OF MANY FROM MISFORTUNES — Union, of the learned — and at lajl — perhaps — Amen. What the meaning of this enigmatical conclufion is we can only guefs ; and we agree with the real philofo- pher from whom we have taken this account, tlint our conjeftures cannot be favourable. Bnhrdt was a villain, and could be aiTociated only with villains, whofe affairs he managed with the help of an old man, who lived at bed and board in his houfe for about fix fliillings a-week, and difcharged the office of fecretary to tlie Union. When he had toiled in this caufe near two years, fome of the fecrets of the Union tranfpired ; his former conduft and his conflant imprudence made him fufpeft- ed r Ills afibciated friends lodged informations as^ainfl him ; his papers were feized ; and he himfelf was fcnt to prifon, firft at Halle and then at Magdcburgh. After fomething more than a year's confinement, he was fet at liberty, and returned to his Ruhe, not, alas ! to live at eafe, or to exhibit fymptoms of repentance, but to lie down on a fick-bed, where, after many months fuf- fering of increafing pain, he died on the 23d of April 1793, the moft wretched and loathlome viftim of un- bridled fenfuality. Such were the fruits of the German Union, and of that Illumination which was to refine the heart of man, and bring to maturity the feeds of native virtue, which are choaked in the heart by fuperftitJou and defpotifm. I ] BAH Dr Bahrdt affcfted to be the enlightener and reformer BatirJt. of the world ; and affirmed that all the evils of life ori- — — %— ginated from dclpotiiin and fuperllition. " In vain (fays he) do we complain of the iuifficacy of religion. All pofitive religion is founded on iiijultice. No prince has a right to prtfcribe or fani\ion any fucii fyilem ; nor would he do it, were not the prleiis the firmcll pil- lars of his tyranny, and fuperftitiou the (Irongclt fetters for his fubjefls. lie dares not (liow Rellstion as ftie is, pure and undcfiled — (lie would charm the eyes and the hearts of mankind, wolild immediately produce true mo- rality, would open the eyes of frceborn man, would teach him what are his rights and who are his oppref- fors, and princes would vanilh h'om the face of the earth." Therefore, without troubling ourfclves with the truth or falfehood of his religion of nature, and alfuming it as an Indifputable point, that Dr Bahrdt has feen it in this natural and fo effeetlve purity, it is furely a very perti- nent qutftion, "Whether has the fight produced on his mind an effedl fo far fuperior to the acknowledged faint- nefs of the impreffion of Chriftlanlty on the bulk of mankind, that it will be prudent to adopt the plan of the German Union, and at once put an end to the di- vlfions which fo unfortunately alienate the nu'nds of pro- feffing Chrillians from each other:" The account here given of Dr Bahrdt's life feems to decide the queftlon. But it will be faid that we have only related fo ma- ny inftances of the quarrels of priefts and their flavifh adherents with Dr Bahrdt. Let us view him in his ordinary conduft, not as the champion and martyr of illumination, but as an ordinary citizen, a hufband, a fa- ther, a friend, a teacher of youth, a clergyman. Wlien Dr Bahrdt was A parlih-minlfter, and prefident of fome ini'^erior ecclefiallical dlftrlft, he was empowered to take off the cenfures of the church from a young wo- man who had born a hallaid child. By violence he again reduced her to the fame condition, and efcaped eenfu; ■■; by the poor girl's dying of a fever before her pregnancy was far advanced, or even legally document- ed. On the night of the fulemn farce of confecrating his Phllanthroplne, he debauched the mald-fervant, who bore twins, and gave him up for the father. The thing was not judicially proved, but was afterwards made fufficiently evident by letters found among his papers, and publiflied by one of his friends in the U N ion. Having fupported thefe infants, in a pltii'^ul manner, for little more than a year, he caufed them to be taken away from their mother, during night, fome time in the month of February 1780 ; and they were found expofed, the one at Ufstein, and the other at Worms, many miles dillant from each other, and almoft frozen to death. So much for the purity of his morals and his reh'- glon, as he appears in the charafter of a father and of a clergyman. His decency as a hulband, and his gratitude to his friend, we have already fceii ; and we ffiall now fee his kindneis and fidelity. After wafting the greateft part of his wife's little fortune, he was fo provoked becaufe her brother would not give him up the remainder, amounting to about .L. no, that he ever afterwards treated her with the greateft cruelty, and exhibited her to contempt and ridicule in two infamous novels. At Halle he brought a millrefs into the houfe, and committed to her the care of his fa- mily, confining his wife and daughter to their own, apartment 5 , B A I [ 62 ] B A I Bi'-rlt, apartment j and the laft thing which he did was to ''''"?• fend for a bookfelK-r, who had i)vibh"lhcd fome of his ' ' vilell pieces, and, without a tliought of his injured wife, recommend hi.i (Irumpet and her children to his protec- tion. "Think not, iiidijrnant reader (fays Arbuthnot), that tl\is man's life is ufelefs to mortals." It (liovvs in a ftri)ncr liglit tlio falfity of all his declamations in favour of his fo much praifed natural religion and univerfiil kindncfs and humanity. No man of the pirtv writes with more perfuafive energy, and, though his petulance and precipitant fclf-conceit lead him frequently allray, no man has occafionally put all the arguments of thcie j.hilofophers in a clearer light ; yet we fee that all is falfe and hollow. He is a vile hypocrite, and the real aim of all his writings is to make money, by foftering the fcnfual propenfitics of human nature, although he fees atid feels that the completion of the plan of the German Union would be an event more deftrudive and hmentable than any that can be pointed out in the an- nals of fuperftition. We will not fay that all the parti- fans of illumination arf hogs of the lly of Epicurus like this wretch ; and it would be extremely unjull to con- fider his vices as the cfFe£ls of his illumination. He was fenfual, ungrateful, and profane, before he was ad- rritted into the order of the Illuminati ; but had the views of tliat order been fuch as were held out to the v.-nrld at large, its fagaclous founder would not have ini- tiated a wretch fo notorioufly profligate as Dr Bahrdt. Their views, however, being to govern mankind thro' the medium of their fenfual appetites, and to reign in liell, rather than ferve in heaven, they could not have employed a better inftrument. Dr Bahrdt was a true difciple of illumination ; and though his torch was made of the coarfeft materials, and ferved only to difcover fights of woe, the horrid glare darted into eveiy corner, roufmg hundreds of filthy vermin, and direftlng their flight to the rotten carrion, where they could beft de- pofite their poifon and their eggs. Whilft the more de- cent members of the Union laboured to pervert the re- fined part of mankind by declamations on the rights of man and the bleflings of liberty, Bahrdt addrefled him- felf to readers of all defcriptlons, and affallcd at once the imagination and the appetites. He taught them, that - religion is an impoflure ; that m.orallty is convenience ; and, with blafphemy peculiar to himfelf, that be and iiis order, by their licentious doSrines, were to complete ike plan and aim of ^ C BAILLY (Jean-Sylvian), who made fuch a figure during the firft years of the French revolution, was born at Paris on the 15th of September 1736, of a family which had been diftlngulfhed painters during four fuc- reffive generations. He was bred to the fame profef- fion, but (bowed an early tafte for poetry and the belles lettres. Chancing, however, to become acquainted with the geometer La Caille, this circumfiance decided his genius, and he thenceforth devoted himfelf to the culti- vation of fcience. He calculated the orbit of the co- met of 1759 ; and on the 29th of January 1763 was received into the Academy of Sciences. In that year he publiflied an ufeful and laborious compilation, being the reduction of the obfervations made by La Caille in 1760 and 1761, on the zodiacal flars. He likewife be. gan to confider the theory of Jupiter's fatellitcs, and, in the competition for this prize queftion of 1764, had a formidable rival in La Grange, who already promifed to B^ become the iirft mathematician in Europe. The re- '*" fults of his invert igat Ions were collected into a treatife published in 1 766, containing alfo the hiltory of that part of aflronomy. In 177 1 he gave a moll curious and important memoir on the light of the fatellitcs, and introduced a degree of accuracy till then unknown in the obfervations of their ecllpfes. His fludies were not confined to the abftraft fciences; for he cultivated letters with fuccefs. His eloges of Charles V. of Cornellle, of Leibnitz, of Mollere, and afterward thofe of Cook, La Caille, and Greffet, were much admired. His eloquence pointed him out as a proper perfon to fill the charge, vacant in 1771, of fe- cretary to the Academy of Sciences ; and, under the patronage of Buffon, lie fl:ood candidate for that en- viable place. He failed : but it was the high birth and promiling talents of the young Condorcet, joined to the adlive influence of D'Alembert, that carried the prize. In 1775 appeared the firfl; volume of the Hillory of Adronomy, which indeed ftrews the path of fcience with flowers, and in every refpeft is a moil valuable work — full of animated defcription, of luminous narra- tive, and intcrtiling detail. His very peculiar ideas concerning the early ftate of Upper Afia gave rile to an ingenious correfpondence and dlfcuirion with the ve- teran philofopher Voltaire, the fubllance of which foon appeared in two volumes, intitled, " Letters on the Ori- gin of Sciences," and " Letters on the Atlantide of Plato." If imagination flione forth in thefe eflays, eru- dition was no lefs confpicuous in a great work compo- fed in the years I78r and 1782, on the fables and reli- gious creeds of antiquity ; which Hill ex His in manu- fcript, and the publication of which would aflTuredly ex- tend the fame of its author, and gratify the learned world. His opinions on fome points happening to co- incide with the theories of Buffon, he contrafted with that celebrated naturaliil a clofe friendrtilp, which was diffolved by Biilly's uncourtly oppofition to the eleftion of the Abbe Maury into the Acatlemie Frangaife. Of that academy he had been chofen fecretary in j 784 ; and he was admitted, in the following year, into the Academy of Infcriptlons and Belles Lettres ; the only inftance, fince Fontenelle, of the fame perfon being at once a member of all the three academies. In the mean- time, the other volumes of the Hlftory of Allronomy lucceflively appeared, and that capital work was com- pleted in 17*^7 by the Hiilory of the Indian and Orien- tal Allronomy ; a prodiicllon of Angular acutenefs, re- fearch, and nice calculation. In 1784 he made an elegant report to the Academy of Sciences on the animal magnetlfm of Mefmer ; and in 1786 another report, which difplays the judgment and humanity of its author, on a projeCl for a new hokl-ilieu or Infirmary. We now approach the eventful period which fum- moned Bailly from his retirement, to enter on a politi- cal career, that was full of difficulty and danger, and for which his habits and lludies appear not to have fitted him. He had fccn, as others faw, the defefts of the old goveriunent (if France. His heart panted for civil and ecclcfiaft'cal liberty ; but unfortunately, like many other philofaphers b'j'h in his own country and in this, he had formed notions of that bleffing which experience fliould have taught him can never be realifed among be- .liy. B A I Bailly, I'ligs fo impei'fcft as the bulk of mankind. When the "■"v ll.itcs-genenil were funimoned to meet, he was on the 2.'>th of April 1789 nominated fecretary by the elec- tors of Paris, and then appointed one of the deputies. He was chofeii prelldcnt of the Tiers Etat ; and when that chamber was conftituted the National Aflembly, he continued in the chair, and concurred in all the le- velling decrees which laid the foundation of the prefent mifery of his country, as well of mofl other countries i,f Europe. After the taking of the Baftile, when the king was removed to Paris on the 15th of July, Bailly was called by public acclamation to the head of that city, with the title of Miiyor. In his feveral fundlions he afted with integrity, courage, and moderation. He reached the fummit of glory : — but how mutable, alas ! is hu- man grandeur ! That middle courfe of conduft, the aurea mediocrhas, at which virtue aims, is fitted to pleafe neither of the contending parties in the midil of revolu- tions ; and fucli proved the ruin of Bailly. His po- pularity began to decline, and was at length changed into inveterate enmity by an unfortunate accident. On the 17th of July 1791, the populace having coUefted tum.ultuoufly to demand the abolition of monarchy, Bailly was ordered by the National AflTcmbly to dif- perfe the mob. He was obliged to proceed to the Champ-de-Mars at the rifle of his life ; and, in fpite of all his exertions and forbearance, fome fliots were fired by the foldiery. It was no longer defir&ble to hold his perilous charge, and on the i6th of November follow- ing he give way to the afcending reputation of Petion. The impaired ftate of his health, too, rendered it expe- dient to retire from the focus of turbulence. He fpent the year 1792 and part of 1793 in travelling through different provinces of. France. During this period he wrote memoirs of the events which he had witneffed, and in which he had often been a principal aftor. Thefe come down only to the 2d of Oiitober 17S9, but would make a large quarto volume ; and La Lande, from whofe Eloge de Bailly this article is taken, gives us hopes that the manufcript will be publifhed. He was advifed by his friends to withdraw from France, but he chofe rather, like Socrates, to fubmit to the in- juftice and ingratitude of his country. At the nod of a vulgar tyrant he was arrelled, fummarily condemned by a fanguinary tribunal, and on the 15th of November 1795 was delivered over to appeafe the vengeance of an incenfed and indifcriminate populace. His fufferings were lludioufly protracted, but he bore them with the calmnefs and magnanimity of a fage. Nature recoils at the recital of inch barbarities. In 1787 INI. Bailly married the widow of one who had been during 25 years his intimate friend ; a wo- man more qualified by her age and condition to infpire refpeft than the paliion of love. He was tall in his perfon, of a ferious deportment, and joined firmnefs to fenfibility . Never did philofopher dillinguifli himfelf in fo many different lines, nor acquire fuch deferved repu- tation in them all. His difintereftednefs was pure and unaffefted ; and during his magillracy he fpent a part of his fortune in relieving the wants of the poor. Plis virtue remained as untainted in his various public fla- tions as in the fweet retirement of domeftic life. Such is the encomium palTed upon this philofopher and flatefman by no lefs a man than the celebrated af- [ 63 ] BAN Baliul II Bar; I am. tronomer'M. db la Lande ; but to thofc who are not infefted with the mama of freedom, it will doubtlefs ap- pear greatly exaggerated. That M. Bailly was a man of eminence in the republic of letters, is known to all the learned of Europe ; that in his political condudt he meant to promote the good of his country, it wouhl certainly be prefumptuous in us to deny ; and that he fuffered unjnUly, is incontrovertible : But let it be re- membered that he fuffered in a llorci, which he exerted all his abilities to raife ; and that he ftt an example of injuitice, when he concurred in the degradation of the privileged orders, and in the violent coniifcation of the property of the church. BALIOL (John), the competitor with Bruce for the crown of Scotland, was not (as he is faid to have been in the Encyclopedia') the brother of King Alex- ander, but the great grandfon of David Earl of Hun- tington, third fon of King David I. BALLISTIC Pendulum, an ingenious machine iinvented by Benjamin Robins, for al'certaining the velo- city of military projeftiles, and confequeutly the force of fired gunpowder. It confills of a large block of wood, annexed to the end of a ilrong iron Item, iiavijig a crofs fteel axis at the other end, placed horizontally, about which the whole vibrates together like the pen- dulum of a clock. The machine being at reft, a piece ;/„//„„v of ordnance is pointed ftraiglit towards the wooden Duiionarj^ block or ball of this pendulum, and then difcharged : the confequence is this — the ball difcharged from the gun ftrikes and enters the block, and caufes the pendu- lum to vibrate more or lefs according to the velocity of the projeitile or the force of the blow ; and by obfer- ving the extent of the vibration, the force of that blow becomes known, or the greatelt velocity with which the block is moved out of its place, and conftqucntly the velocity of the projectile itfelf which ilruck the blow and urged the penduluaa. BANKA (fee Banca, Encyd.) is noted tlirougho!!t Afia for its tin mines. It lies oppofite to the river P,i- lambang, in the ifland of Sumatra, on which the fovc- reign of Banka, poffelfor alfo of the territorj- of Palam- bang, keeps his conllant refidence. This prince main- tains his authority over his own fubjefts, and his inde- pendence of the neighbouring fovereigns, chiclly by the affillance of the Dutch, who liave a feltlement and troops at Palambang, and enjoy the benefit of a contraft with the king of Banka for the tin which his fubjefts procure from that ifland. Such at leall was the cafe in 1793, when Lord Macartney touched at Banka on his way to China. At that period the fovereign compelled his fub- jefts, and probably does fo at preient, to deliver the tin to him at a low price, and iold it to the Dutch at a fmall advance, purfuant to his contract. Thofe miners, from long practice, have arrived at great perfection in redu- cing the ore into metal, employing wood as fuel in their furnaces, and not foflile coal, oxcoai, which is feldom io free from fulphur as not to afiedl the malleahility of the metal. It is lometimes preferred therefore to European tin at the Canton market ; and the profit upon it to the Dutch company was, at the period mentioned abo\c, luppofed to have long been not lefs than L. 150,000-2- year. Into whofe hands this trade has now fallen we know not ; probably it is in a great degree negleilled. BANTAM, the capital of a kingdom of the fame name in the ifland of Java, is, in the Encyclopedia, faid BAR [ 6+ ] BAR Bariib. Bartam to be a large town with a good harbour anrl fortified cattle Sir George Staunton, however, who vifited Ban- tam fince that article was publiflud, gives a very ditle- rent accoi'nt both of the town and of its harbour. Once indeed it was a place of confiderable confequence, being the great mart for pepper and other fpices, whence they were diftribnted to the reft of the world The chief faftory of the Engh'fii as well as Dutch Eaft India Com- pany was fettled there. The merchants of Arabia and Hindoftan rcforted to it. Its fovercigns were fo deii- rous of encouraging trade, by giving ftcurity to foreign merchants againll the violent and revengeful dilpofition of the natives, that the crime of murder was never par- doned when committed againft a Rranger, but might be commuted by a foreigner for a fine to the relations of the deceafed. This place flourilhed for a confiderable time ; but the Dutch having conquered the ntiglibour- ing province of Jacatra, where they fince have built Ba- tavia, and transferied their principal bufinefs to it, and the Englifh having removed to Hindoftan and China, and trade in other rcfpefls having taken a new courfe, Bantam was reduced to a poor remnant of its former opulence and importance. Other circumilances have accelerated its decline. The bay is fo choakcd up with daily acc^ffions of new earth waflied down from the mountains, as well as by coral (lioals extending a confi- derable way to the eallward, that it is inacceflible at prefent to velTels of burden ; even the party who went there from the Lion, the fliip which carried Lord Ma- cartney to China, was obliged to remove from her pin- nace into a canoe, in order to reach the town. With the trade of Bantam the power of its fovereign decli- ned. In his wars with other princes of Java he called in the affiftance of the Dutch ; and from that period he became in faft their captive. He refides in a palace built in the European ftyle, with a fort garrifoned by a detachment from Batavia, of which the commander takes his orders not from the king of Bantam., but from a Dutch chief or governor, who lives in another fort adjoining the town, and nearer. to the fea-fide. His Bantamefe majefty is allowed, however, to maintain a body of native troops, and has feveral fmall armed vef- fels, by means of which he maintains authority over fome parts of the fouth of Sumatra. His fubjefts are obliged to fell to him all the pepper they raife in either ifland, at a low price, which he is under contraft with the Dutch to deliver to them at a fmall advance, and much under the marketable value of that commodity. The prefent king joins the fpiritual to the temporal povi'er, and is high prieft of the religion of Mahomet ; with which he mingles, indeed, fome of the rites and fuperftitions of the aboriginal inhabitants of Java ; ado- ring, for inftance, the great banyan, or Indian fig-tree, which is likewife held facred in Hindoftan, and under which religious rites might be conveniently performed ; in like manner, as all affairs of ftate are actually tranf- afted by the Bantamefe under fome fliadowiiig tree by moon-light. To complete the ruin of Bantam, a fire fome time ago deihoyed moft of the houfes, and few have been fince rebuilt. BANYAN-TREE. See Ficus, .E«o''/. British BARILLA, is the name given by Mr James King of Neweaftle upon Tyne, to a material in- vented by him to fupply the place of Spanilh barilla in the making of crown window-glafs, broad window-glafs, and glafs-boltles, as alfo in the manufafturing of foap and alum. For thefe purpofes he affirmed that it an-'^ fwercd much better than any other material then in ufe J and in confequence of that affirmation he obtain- ed a patent for his inv>;ntion, dated March 4. 178". Tliough we can hardly allow to this invention all the merit claimed for it by its fond author, yet as it niuy be of ufe to different manufadturers, we (hall lay before our readers his method of making the Britilh barilla. It is as follows : " Take a certain quantity of aAies ob- taiiud by burning the loppings or branches of afti, oak, beech, elm, alder, or. any other kind of green wood or bramble : Take an equal quantity ol the allies obtained by burning the green vegetables known by the name of fern, brecon, bean and pea-ftraw, whins, common field and high-way thiftlcs, the ftalks of rape or muftard- feed, or the bent or ruftics that grow by the fea-fliore." Though we know not in wlial qualities tlie afties ob- tained from the former fubftances differ from thofe ob- tained from the latter, the author, as if the difference was very great, directs thefe equal quantities to be mix- ed together, fifted through a fine ficve, and laid upon a boarded floor, where a quantity of foapers wafte-afties, equal to the whole compound mafs, is to be added to it, and well mixed with it by means of a ftiovel or other inftrument. To this mixture of vegetable alhes and foapers wafte-afhes is to be added a quantity of fine quick-lime, in the proportion ot one hundred weight to twelve hundred of the blended aPiies, and the lime and aflies are to be well mixed together. After this the whole is to be put into an iron pan, into which is to be poured a quantity of feawater fufficicnt, fays the au- thor, to diffolve the affies and lime ; and the whole is to he ftirred with an iron rake till it incorporate. This being done, a coal fire is to be lighted up under the pan, and kept burning for two days and two nights without intermilTion, additional quantities of fea-water being conftantly fupplied to impregnate the materials with fa- line inatter fufficient for calcination in a reverberating furnace or caicar. In this calcar the ialine mafs, which was bciled in the pan, is by intenfe heat to be diffolved, and kept in a ftate of fufion for the fpace of an hour ; during which time the volatile part flies off, and leaves remaining a fixed alkaline fait, which, cooled in iron pans, is the Britifn barilla, and has the appearance of Spanifli barilla. See Barilla, Encycl. BARTHELEMI (Jean Jacques), the Neftor of French literature, was a man fo eminent for his know- ledge of antiquities, that every claffical reader mull be iiiterefted in his fate. He was born, we believe, at Pa- ris about the latter end of the year 171c ; and being educated for the fervice of the church, he became prior of Courcay, keeper of the medab and antiques in the French king's cabinet, and in 1 747 was eletted a mem- ber of the Academy of Infcriptions. From that period his life was wholly devoted to letters ; and in recording the principal events of it, we can only enumerate, in their order, his various publications. A differtation of bis on the river Paftolus was read 1748 [Hift. del' Acad. X. 29.) ; Refleaions on a Me- dal of Xerxes, King of Arfamata (Mem. de I' Acad. XXXVII. 171.), found, or faid to be found, by Four- moiit in the temple of Apollo Anyclcus (^XXXIX. 129.); Effay on Numifmatic Palaeography, ib. 223; Differtation on two Samaritan Medals of Antigonus Kinsr Barilla, irihelenii. BAR r 65 ] BAR King of Judca, ii. 257 ; Remarks on Come Iiifci-iptions publifhed by dilTcrcnt authors, XLV. 99 ; DiiTertation on Arabic Coins, ili. 143 ; by which it appears that the Mohammedan princes copied the heads of Greek and Roman ones on their coins, and gave Arabic infcrip- tions of their own names on the reverfe. On the An- cient Alphabet and Language of palmyra, ;i. 179 ; on the Ancient Monuments of Rome, the refult of a tour in Italy to coUciit medals for the royal cabinet, to which he added 300, XLIX. 151 ; on fome Phoenician Mo- numents, and the Alphabets formed from them, LIII. 23. The charafters on the written mountains, which he here cites, have been proved of no value ; and he il- luftrates tlie conformity between the Phoenician and the Egyptian charaders from the latter on the banda- ges of the mummies. Iixplar;ation oi the Molaic Pave- ment of the Temple of Prsentue, ii. 149; of which there have been four engravings fmce its firll dilcovery in 1 650, and which Barthelenii refers to the voyage of Adrian into Egypt. It may be of that date, but there is no reafoii to fuppofe that it reprefcnts any thing more tlian an Egyptian landfcape. 'I'he form of letters determines the date in the judgment of the learned Abbe. On the Relations of the Egyptian, Phosnician, and Greek Languages, LVIl. 38 ^ ; on fome Medals publilhed by different authors, LIX. 270; Explanation of an In- fcription under a Bas-relief in the Bilhop of Carpen- tras's Library, 1 767, ii. 365 ; on the Number of Pieces reprcfentcd in one Day on the Theatre at Athens, LXXIL 286 ; three Comedies, as many Tragedies, a Satire, and a Petite Piece; Remarks on fome medals of the Emperor Antoninus ftruck in Egypt, LXXX. 4S4. '775.(a). His iaterpretation of the Phoenician infcription at Malta, LIII. 23, was controverted by our learned lin- guift, Mr Swinton, in Philaf. Traniacl. LIV. art. xxii. p. 119; in farther remarks, ii. art. Ixx. P'^93. In 1792 he publilhed a difl'ertation on an ancient Greek infcription, containing an account of expences of the public fealls under the archontate of Glaucippus, 410 years before Chrifl. The intimate acquaintance which he had cultivated with claffical antiquity, enabled him, in the clofe of a long life, to compofe that cbcf-d'au-cre, the " Travels of the Younger Anacharfis iiito Greece" in the mid- dle of the lourth century before the vulgar, era. In re- prefenting the curiofity of a Scythian favage (for we cannot confider iji any other light the man who put rriufic and the exceffes of the table on the fame level), he takes occafion to interweave very curious and inllruc- tive details on the laws, religion, manners, cuftoms, and general fpirit, ot a gi-eat nation, as well as its progrefs in arts and Iciences. The epoch which he has chofen is that of letters and arts, combining the age of Pericles with tliat of Alexander, the revolution which changed the appearance of Greece, and foon after overturned the empire of Perfia. The introduftion comprehends the 1250 years elapfed from the age of Cecrops to the fup- pofed era of Anacharfis, in two intervals; the iirft reach- ing to the commencement of the Olympiads, the fecond to the capture of Athens by the Lacedemonians. The SuppL. Vol. I. Part I. hi (lory of the .\ihcnians commences about ijo years Bartlie. after the firft Olympiad, including the age of Solon, or ''^''''• that of legiflatioH ; that of Themiftocles and Ariilides, ' or that of glory, of luxury, and arts. Jn the fecond, fpcaking of war, his oblervation, that " the example of one nation, that prefers dcatli to (lavery, is tdo import- ant and too inftrudlive to be pafled in filence," fliould have preferved him from the horrors of a long confine- ment in an advs'.iced age, from which he was delivered only to die. But arts, fcienccs, and literature, are alike forgotten and overwhelmed in France. In the third interval, fpeaking of the corruption of manners intro- duced by Pericles to fupport his power, he has this ob- fervation, applicable to every ftate : " Corrupted mo- rals are not reftored but by the lofs of liberty, which brings that poverty inconfiftent with foftnefs, and infe- parahle from abftemioufnels, if not that rigid principle of a healthy mind, which is properly called virtue.'" In this period, though the arts were encouraged, philofo- phy was neglefted. In this diverfilicd undertaking, where the piif\ure of ancient Greece, in its minuted parts, both of public and private ufe, is brought before our eyes, the Abbe is fre- quently more bi-illiant than folid, and occafionally lofes the fubllance of a refleftion in purfuit of fomething in- genious to add to it. The plans, views, .and maps, are executed with great fpirit and accuracy by Mr Bar- ber, a young man of very promifing talents ; and to the charts many ufeful tables are added. The beauties of the clafTics are diffufed in a vei"y pleafing manner, and interfperfed with anecdotes little known. Such was the man whom the French government detained in prifon for months, and releafed on the fall of Robefpierre. As he concurred in the revolution, we know of no caufe for his imprilonment but the mildnefs of his difpofition, and the jealoufy of that tyrant, which purfued, with relentlefs cruelty, every man fufpefled of being a friend to peace. Of the perfecution of Barthe- lemi, in the extremity of old age, the convention itfelf feemed to be afhamed ; for it unanimoufly voted him a penfion < s fome recompence for his fufTerings. But, alas! the recompence came too late : the old man lived but a few months after his liberation, having died at Paris on the 4th of May 1795 ; and the day after the fol- lowing tribute was paid to his memory by Duflaulx, in the national convention : " Legiflators, your liberality conferred honour on the latter days of the life of our refpeflable fellow citizen, Barthclcmi. Our fuccedors, I have no doubt, will confccrate his memory fo foon as the period fixed by the law fliall permit them. May his old friend, how- ever, be permitted, in a few words, to point out the rare qualities of that Neftcr of French literature ? It might, perhaps, be fufficient to tell you, as Xenophon faid with fo much fimplicity of one of his mod illuftrious con- temporaries, that Barthelemi was an excellent man in all refpefts. In faCt, thofe who knew him were at a lofs which to admire mod — his immortal Anacharfis, or his own life. His policy confided in goodneis ; his fcieiice was an immenfe treafure of every thing that could purify the morals, perfeft the tade, render man I more (a) The references hereare to the duodecimo edition of the Memoirs of the Academy of Infcriptions- Bat. BAT [6 Barthelemi more dear to man, and contribute to the fplendour of his country. A ilnifle trait will convince you of the _ mildnefs of his philanthropic mind : ' Why is it not permitted (he often faid) to a mortal to bequeath prof- perity to his fellow-creatures?' After having been over- whelmed with the favours of fortune, whicli came un- expeftedly and unfought, he became poor ; yet his cha- rafter, far from ilnkiiig under the prefTure, actpiired new rcfpeft; and he proved that poverty, fiipported with dignity, is not lefs honourable than wealth accompanied with benevolence. Perl'ecuted, as all virtuous and en- lightened citizens were, he carried with him to the dun- geon of that tyranny which you have fo glorioufly de- liroyed, the conftancy and ferenity of Socrates. It was there that the venerable old man offered to his compa- nions in misfortune the magnificent fpeftacle of a good man (Irugcrliug with adverfity. I have faid that he was rich ; but let us not forget that he was not rich at the expence of the unfortunate, and that he adopted all the branches of his numerous family. The republic has gained by that family good citizens, who ferve her ia the moil ufeful and brilliant manner. Barthelemi felt that the period of his dilfolution was approaching; yet though exhaulled by long fatigue, and bending beneath the weight of 80 years, his fenfihillty was dill vigorous, and your juft decrees made the clofing fcene of his hfe happy. When he heard that you were endeavouring to repair the ills under which fo many thoufand innocent men laboured, he lifted up his hands to heaven, and exclaimed, ' Glory to God — honour to the national convention — I have lived long enough!' In the pre- fent pofture of affairs, the country demands all your at- tention. I fhall therefore confine myfelf to requeft the favour due to the manes of the illuftrious Barthcle- mi. One of his nephews, I do not mean your refpec- table ambaffador at Bafle, but the citizen Courcey, has, for 25 years, difcharged all the duties of a fon to his uncle, and for a long time has performed the funftions of keeper of the medals and antiquities of the national cabinet. I move, that the citizen Courcey be appoint- ed to that office, which he has already proved himfclf fo worthy to fill." Whatever became of this motion, which was referred to the committee of pubhc inftruftion, the cruelty of the government purfued the family ; and the late banilh- ment of his other nephew by the directory, of which he was a member, furpatfes, if pofTible, the injuftice of Robefpierre to the uncle. But their crimes were the fame : both Barthelemis were men of mild difpofitions and friends to peace. BARYTES, one of the earths. See Chemistry in this Supplement, Part I. Chap. iv. BASTE R, the name given by the Dutch at the Cape of Good Hope to the offspring of a white man and Hottentot woman. BAT, an animal which has been defcribed under its generic name VESPtRxiLLio in the Encycl. but fince that article was written, we have met with an account of a new fpecies, fo very fingular, that, if the veracity of our author can be depended on, it is well intitled to a place here. This fpecies was difcovercd in the country of the NImiquas, in the interior of Africa, by M. Vaillant, during the courfe of his fecond travels, and Is by him called the oreillar bat. To this title it hai indeed a very good claim ; for it has, he fays, four i) ] BAT ears, or at leaft the external part of four ears, each B^tavfa. tar being double ; the outer fold, which ferves as v~~" a covering to the inner, is very ample, being two inches eight lines high, and nearly as broad when ftretched out. On the nofe alio a membrane Hands ercft, one inch four lines in height, which might be taken for an- other car, as it has exactly the fhape of one. This membrane, as well as the ears and wings of the animal, are of a rully red, paler below than above. The body is only three inches long, and is covered with very fine greyilh hair. Its width, from the tip of one wing to that of the other, is eight inches. The reader will par- don me, fays our author, for inferting thefe trifling de- tails of meafurement, of which I am not more fond than himlelf ; but they appeared to me neceffavy here, to convey an accurate idea of the extraordinary length of the ears of this animal, which are certainly larger in pro- portion than thofe of any other we are acquainted with, ilnce they are only four lines, or the third part of an inch, fhorter than the body itfelf. liATAVIA, the capital of the Dutch fcttlements in the Ealt Indies, has been already defcribed under the article Java in the Encyclopedia. The following ac- count of it, however, as well as of the country around it, and the manners and cuiloms of its various inhabi- tants, as they prefented themfelves to Sir George Staun- ton in March 1793, will probably prove acceptable to many of our readers. The city of Batavia, including the fuburbs, confifts of near eight thoufand houfes, inhabited by Dutch, Chinefe, and natives of Java. The houfes of the Chi- nefe are low, and crammed with people. The Dutch houfes are well built, clean, and fpacious, and their con- flrutlion for the moil part well fuited to the climate. The doors and windows are wide and lofty. The ground floors are covered with flags of marble, which being fprinklcd frequently with water, give a pleafant coolnefs to the apartment ; but a confiderable propor- tion of thofe was untenanted, which denoted a declining fettlement. Among other circumflances which announ- ced the fame, were thofe of the Company's vefTels lying ufelels in the road, for want of cargoes to fill, or men to navigate them; no fliips of war to proteft their com- merce, even againfl pirates who attacked their veflel? fometimes in the fight of Batavia road ; an invafion threatened from the Ifle of France ; the place in no con- dition of defence, particularly againll an enemy lefs af- fected by the climate than Europeans ; fometimes as many of the troops in hofpitals as fit for duty ; com- milhoners expected from Holland to reform abufes. Such a commiffion, implying a general fufpicion, could not be welcome ; nor was it quite certain whether, in fome minds, its arrival, or that of the enemy, was depre- cated the moft cordially. The fortifications of Batavia, though a place of fo much importance, were not, when Sir George faw them, fuch as would be deemed formidable in Europe ; but when the difficulties were confidered of forcing the pafFage of the river, or of landing troops on other parts of the ifland, it might perhaps be thought of greater ftrength than it would at the firft view have credit for. The defences of the river were the water fort, fituated at its entrance, having mounted or dif- mounted fourteen guns and two howitzers. It con- filled of a parapet, originally well conftrufted, retained by BAT [ 67 ] BAT Batavia. by a wall ; but the parapet was miicli negle£led, and ■"v"— ' the wall nearly dcftroyed by the conftant working of the fea. This fort was protected on the land fide by a noxious fwamp, and towards the fea, on the north- weft, by extenfive flats, over which even boats could not pafs. The only good approach was that by the channel, which it fees and defends. The next work upon the river was on the weft (here, about a quarter of a mile from the water fort. It is a battery mount, ing feven guns, bearing down the river. Oppofite to this was a battery of fix guns, facing tlie river, and two to the eaftward. This formed one flank of a line that occupied the low land to the north-eaft of the town. The line was a low breaft-work of earth, that was fcarcely difcoverable. The canals which interfeil the town joined the great canal or river, at the diftance of half a mile from the entrance. Below the junftion a boom was laid of wood, armed with iron fpikes. A little above was the caftle, a regular fquare fort, but without ravelins or other outworks. It had two guns mounted on each flank, and two, or fometimes three, on each face : they were not en barbette, nor properly en embrafure, but in a fituation between both, having both their difadvantages without the advantage of cither. The wall was of mafonry, about 24 feet high. It had no ditch, but a canal furrounded it at fome diftance. It had no cordon. The length of the exterior fide of the work was about 700 feet. The town is rectangular, three quarters of a mile long, and half a mile broad, inclofed by a wall of about 20 feet in height. Small pro- jeftions were conftrufted, of various forms, at intervals of about 3yofeet. Thefegenerallymountedthree guns each. It was alfo furrounded by a canal, having feveral lluices. At ihort diftances from the town, three or four fmall ftar forts of earth were ereftcd in particular pafles, per- haps for defence againft the inhabitants of the ifland. The eftablifhment of regular troops was i 200 Euro- peans, of whom 300 were to be artillery, the reft infan- try. But as it was found impoilible, on account of the climate, to keep the number complete, recourfe was had to the natives, of whom 500 were employed ; fo that tlie eftabliftiment of European regulars was reduced to 700. There were alfo 300 volunteers of the town, who were formed into two companies, but they were not difciplined. Their regulars were very numerous, con- fifting of enrolled natives of Java, who were never em- bodied, and of Chinefe, of wliom the Dutch were fo jea- lous as to arm them with lances only. Much depen- dence was not to be placed on the exertions of eitiier of thefe bodies in favour of the Dutch ; and as they lofe many of their European troops every year, their eftabliftiment appeared too fmall for any efl'cftual re- Cftance. The chief proteftion of their ill-manned vef- fels lying here, muft be from the fortified ifland of On. ruft, well fituated to command tlie channel that affords the principal paffage in\o the road. The work upon that ifland was of a pentagonal form ; its baftions were fmall and low, not more than 12 feet the higheft, and not always connefted by curtains. A few batteries were lately conftruAed on the outfide of this work, that bore towards the fea. On thefe and on the baftions about 40 guns were mounted in different diredtions. South of thefe was another ifland, at the diftance of a few hundred yards, on which two batteries, mounting together 12 guns, had been lately erefted. The caftle is built of coral rock, brought from fomc Batavia. of the adjoining iflands, compofed of that material ; and '— V— has the advantage of a fortilication of brick, in which cannon ball is apt to bury itfelf without fpreading Iplin- tcrs or Ihattering the wall. A part of the town wall is built of lava, which is of a dark blue colour, of a very hard denfe texture, emits a metallic found, and refem- bles very much fome of the lava of Vefuvius. It is brought from the mountains in the centre of Java, where a crater is ftill fmoking. No ftone of any kind is to be found for many miles behind tlie city of Batavia. Mar- ble and granite are brought thither from China, in vcf- fcls belonging to that country, commonly called junks, which generally fail for Batavia from the ports (rf the provinces of Canton and Fokien, on the fouthern and foutheaft coalh of that empire, laden chiefly with tea, porcelain, and filks. The chief proteftion of Batavia againft the attacks of a foreign enemy, arifes from the havoc which it is well known the climate would make amongft Euro- pean troops. This was acknowledged to Lord Ma- cartney by fome of the Dutch officers themfelves, and even by one of the counfellors of the Indies. Such in- deed is the climate, that there have been very few ex- amples of ftrangers remaining long in Batavia without being attacked by fever, which is the general denonn'na- tion in that place for illnefs of every kind. Europeans foon after their arrival firft become languid and feeble, and in a few weeks, or even in a few days, are taken fe- rioufly ill. The diforder at firft is commonly a tertiaa ague, which after two or three paroxyfms becomes a double tertian, and then a continued remittent, that fre- quently carries off the patient in a flrort time. Many fall vidtims to the fecond or third fit; but in thefe cafes a conftant delirium, and a great determination of the blood to the brain, accompany the other fymptoms. In fome it begins iu a quotidian form, with regular inter- miffions for a day or two ; and then becomes a continued remittent, attended with the fame fatal confequences as the former. Of the Europeans of all clafles who come to fettle at Batavia, it is fuppofed that not half the num. ber always furvives the year. The place refcmblcs \a that refpetl a field of battle or a town befieged. The frequency of deaths renders familiar the mention ofthem, and little figns are flievvn of emotion or furprife on hear, ing that the companion of yetterday is to-day no more. It is probable, female Eurojieans fuller lefs at Batavia than the men. The former feldom cxpofe themfelves to the heat of the fun, make frequent ufe of the cold liath, and live more temperately than the other fex. But it is not to thofe who have htely arrived from Europe that this havoc is wholly confined. The great, eft number of the Dutch fettlers, even thofe who had refided long in the country, appeared wan, weak, and languid, as if labouring with the " difeafe of death." Their place of refidence, indeed, is fituated in the midft of (wamps and ftagnated pools, from whence they are every morning fainted with " a congregation of foul and peftilcntial vapours," whenever the fea breeze fcts in, and blows over this morals. The meridian iun raifes from the fliallow and muddy canals, with which the town is interfefted, deleterious miafmata into the air ; and the trees, with which the quays and ftreets are crowded, emit noxious exhalations in the night. The general reputation of the unhcakhinefs of Bata- I 2 via BAT C 68 ] BAT Batavia. via is indeed fuch as to deter even Dutclimen, who can » reiide at homt; with any comfort, from coming to it, notwithftanding the temptation of fortunes to be quick- ly amaffed in it. From this circuniftance it happens, that offices and proftfTioriS are often neceffarily entrull- ed to perfons little qualified to till them. One of the clergymen, and the principal phyfician of the place, were both faid to have originally been barbers. The Uni- ted Provinces fnrnilh even few military recruits. The reft are chiefly Germans, many of whom are faid to have been kidnapped into the fervice. Though nonrrinally permitted, after a certain length of time, to return home, they are in faft compelled to enlill for a longer time, the pay being too fcanty to allow them to lave enouo-h to defray the expence of their palTage to Eu- rope. The government is accufcd ot the barbarous po- licy of intercepting all correfpondence between thofe people and their mother country; by which means they are deprived of the confo'.ation of hearing from their friends, as well as of the chance of receiving fuch af- flftance as might enable them to get home. Difficult, however, as it is, on account of the cU- mate, to recruit the army, fucli is the defire of accumu- latiniT wealth in a foreign land, that it draws annually trreat numbers of Chinefe as well as of Dutch to Bata- via. Both indeed belong generally to the humbler claf- fes of life, and are bred in fimilar habits of indullry in their own country; but the diflerent circumftances that attend them after their arrival in Batavia put an end to any further refemblance between them. The Chinefe have there no way of getting forward but by the conti- nuance of their former exertions in a place where they are more liberally rewarded, and by a ftriiSt economy in the prefervation of their gains. Tliey have no chance of advancing by favour, nor are public offices open to their ambition ; but they apply to every induftrious oc- cupation, and obtain whatever either care or labour can accomplith. They become in town retailers, clerks, and agents ; in the country they are farmers, and are the principal cultivators of the fugarcane. They do at length acquire fortunes, which they value by the time and labour required to earn them. So gradual an acquifition makes no change in their difpofition or mode of life. Their induftry is not diminilhed, nor their health impaired. The Dutch, on the contrary, who are fent out by the Company to adminiller their affairs in Afia, become foon fenlible that they have the power, wealth, and pofleffions of the country at their difpofaL They who furvive mount quickly into offices that are lucrative, and not to them laborious. They rife to the dignity of governor- general and coimfellors of the Indies, as the members of the Batavian govern- ment are called. Their influence likewife enables them to fpeculate in trade with vail advantage. The drud- gery and detail of bufinefs are readily undertaken by the Chinefe ; w.hile their principals find it difficult, un- der fuch new circumftances, to retain their former ha- bits, or to reCIt a propenfity to indolence and voluptu- oufnefs, though often attended with the facrifice of health, if not of life. Convivial pleafurcs, among others, are frequently carried to excefs. In feveral ftoufes of note tlu'oiighout tlie fettlement, the table is fpread in the morning at an early hour : befide tea, coffee, and chocolate, fifli and flefli are ferved for breakfaft ; which is no fooner over than Madeira, claret, gin, Dutch fmall beer, and Engh'ffi porter, are laid out in the portico before the door of the great hall, ■ and pipes and tobacco prefeiitcd to every guell, and a bright brafs jar jilaccd before him to receive the phlegm which the tobacco frequently draws forth. Tliis oc- cupation continues fometimcs with little interruption till- near dinner time, which is about one o'clock in the af- ternoon. It is not very uncommon for one man to drink a bottle of wine in this mauner before dinner; and thofe who have a prediledtion for the liquor of their own country fwallow feveral bottles of Dutch fmall beer, which they are told dilutes their blood, and affords plenty of fluids for a free perfpiration. Immediately before dinner, two men flaves go round with Madeira wine, of which each of the company takes a burv^per a$ a tonic or whettcr of the ajipetite. Then follow three females, one with a filver jar containing water, fome- times rofe-water, to walh ; a fecond with a filver bafon and low cover of the fame metal, pierced with holes, to receive the water after being ufed ; and the third with towels for-wiping the hands. During dinner a band of mufic plays at a little diltance : the muficians are all flaves, and pains are taken to inftruCt them. A confi- derable number of female flaves attend at table, which is covered with a great variety of difhes ; but little is received, except liquors, into ftomachs already cloyed. Coffee immediately follows dinner. Tiie 24 hours are here divided, as to the manner of living, into two days and two nights ; for each perfon retires, foon after drinking coffee, to a bed, which confifts of a mattrafs, bolfter, pillow, and chintz counterpane, but no flieets ; and puts on his night drefs, or muflin cap and loofe long cotton gown. If a bachelor, wliich is the cafe of much the greatcll number, a female flave attends to fan him while he fleeps. About fix chey rife, drefs, drink tea, take an airing in their carriages, and form parties to fpend the evening together to a late hour. The morn- ing meetings confift; generally cf men, the ladies feldont choofing to appear till evening. Few uf thefe are natives of Europe, but many are defcended from Dutch fettlers here, and are educated. with fome care. The features and outlines of their- faces are European ; but the complexion, charafter,. and mode of life, approach more to thofe of the native inhabitants of Java. A pale languor overfprcads the countenance, and not the lea.l tint of rofe is feen in any cheek. While in their own houfes they drefs like their flaves, with a long red checkered cotton gown defcend- ing to the ankles, with large wide fleeves. They wear no head-drefs, but plait their hair, and faften it with a filver bodkin on the top of the head, like the country girls in feveral cantons of Switzerland. The colour o€ their hair is almoit univerfally black; they anoint it with the oil of the cocoa nut, and adorn it with chap* lets of flowers. When they go abroad to pay vifits,. or to take an airing in their cairiages, and particularly when they go to their evening parties, they drels mag- nificently, in gold and filver fpangled muflm robs, with a profufion of jewels In their hair, wiiich, howevc'', is- worn without powder. They never attempt to mould or regulate the fliape by any fancied idea of elegance^ or any ftandard of faflilon ; and confequently formed a. ftriking contraft with fuch few ladles as were lately ar- rived from Holland, who had powdered hair and fair complexions, had eontrafted their waifts with ftayb, wore- Pa'at B A 1' wore large head-dreflcs and hoops, and prrfcvered in tlie -' early cart of forcing back the elbows, c!n'n, and flioul • dcrs. Every native lady is conftantly attended by a fe- inale flave handfomely habited, who, as foon as her mi- ftrefs is feated, fits at her feet before her, on the floor, holding in her hands her millrefs's gold or filver box, divided into compartments, to contain arecanut, carda- mom feeds, pepper, tobacco, and llaeiied lime ; all which, mixed together irf due proportions, and rolled within a leaf of betel, conftitutc a maftlcatory of a ve- ry pungent talle, and in general ufe. When in the public affemblies the ladies find the heat difagreeable, they retire to free themfclves from their coftly but in- convenient habits, and return without ceremony in a more light and loofe attire, when they are fcarcely re- cognizable by ilrangers. The gentlemen follow the ex- ample ; and throwing off their heavy and formal dreffes, appear in white jackets, fometlm.es indeed adorned with diamond buttons. The elderly gentlemen quit their periwigs for night(^aps. Except in thefe moments the members of this government have always combined their perfonal gratification with the eaftern Policy of ftriking awe into vulgar minds, by the affumption of exterior and exchifive diftinftions. They alone, for inllance, appear abroad in crimfon velvet. Their carriages are diilinguiflred by peculiar ornaments. When met by others, the latter muft ftop and pay homage to the for- mer. One of the gates of the city is opened only to let them pafs. They certainly fuccced in fupporting abfolute fway over a vaft fuperiority in number of the defc-ndants of the original inhabitants of the country, as well as of the (laves imported into it, and of the Chi- nefe attracted to it by the hope of gain ; thofe clafles, though healthy, aftive, and as if quite at home, readily obeying a few emaciated Europeans. Such is the con- ftquence of dominion once acquired; the prevalence of the mind over mere bodily exertions, and the effeft of the combination of power againft divided ilrength. The native Javanefe are in general too remote from civilization to have any wants that are not ealily fatis- tied in a warm and fertile climate. No alteiYipt i-s made to enflave their perfons ; and they find the government of tlie Dutch lefs vexatious- than that of others, v/ho divide fome ihare of the fuvereignly of the ifland with them. The fultan of Mataran rules to the eafl, the em- peror of Jsva in the centre, and the king of Bantam to f 69 ] B A T true, as the fame accounts pretend', that tie number of- Bi-tavra. female births exceeds very confiderably that of males in '— v— — Java. Mod of the flaves arc imported Into it from Celebes and other eaftern illands. I'hey do not form a corps, or have any bond of union : nor is the general conduft of their owners, towaids them calculated to aggravate the misfortune of being the property of others. They are not forced to exccffivc laboin-. They have fufEcient fuilenance ; but many of the males among them, who had formerly perhaps led an independent life till made captives in their wars, have been found to take offence againft their mafters upon very flight occafionj, and to wreak their vengeance by aflaffir.ation. The apprthen- fion of fuch an event is among the motives for prefer- ring at Batavia female flaves for every ufe to which thty can be applied ; fo that the ni;mber purchafed of them much exceeds that of the other fex. The Haves when determined on revenge often fwallow, for the purpofe of acquiring artificial courage, an extraordinary dole of opiuin, and foon becoming frantic as well as defperate, not only ftab the objefts of their hate, but fally forth to attack in like manner every perfon they .T.icet, till felf-prefervation renders it neceflary to deftroy them. They are faid in that ftate to be running a mud; and inflances of it are not more common among flaves than among free natives of the country, who, in the anguilh for lofing their money, effefts, and fumetimes their fa- milies, at gaming, to which they are violently addified, or under the preffure of fome other pailion or misfor- tune, have recourfe to the fame remedy, with the fame fatal effefts. In the country round Batavia the eye locks in vain for the common animals and vegetables which it had been daily accuftomed to meet in Europe. The moft familiar bird about the houfe of the ambalTador's hoft was the crown bird, as it was called at Batavia, which was not, however, the arclea pavonina of Liun^us, but; the columba crtflata, having nothing except its crcft in common with the former. The fame gentleman had al- fo at his country-houfe fome large caflbwary birds, which, though long in his poffefilon, and having the ap- pearance of tamenefs, i'ometimes betrayed the fiercenefs of their nature, attacking with tiieir (Irong bill thofe who apjnoached too near them. The vcTttation of the country is likewife new. E\vn the parterres in the the weft ; while the coaft and effeftive power almoft gardens are bordered, inllead of boxwood, by the Ara entirely belong to Holland. Thole other fovereigns are defcended from foreigners aho ; being Arabians, who imported the Mahometan religion into Java, and acquired the dominion of the country ; a few inhabi- tants in the mountains excepted, who have prefcrvcd their independence and their faith, and ainong other ar- ticles that of the tranfmigration of iouls. According to the Dutch accounts, nothing can be more tyrannic than thofe Mahometan rulers. The Emperor is faid to maintain his authority by an army of many thoufand men difperfed throughout his territories, befide a nume- rous female guard about his perfon. Thefe military la- dies are trained, it feems, to aiTns, without neglctting thofe aceomplifliments which may occafion a change in the occupation of fome among them, rendering them the companions, inftead of being the attendants, of his Imperial majefty. This fingular inftitution may owe its origin to the facility of obtaining recruits, if it be bian jcfTamine, of which the fragrant /lowers adorn the pagodas ot Hindoltan. The Dutch, who are fo fond ot gardens in Holland, have transferred that taile, where it can certainly be cultivated with more fuccefs, and in- dulge it to a great extent at their houfes a little way from the city of Batavia ; but ftiU within that fenny diftriA, concerning which an intelligent gentleman up- on the foot nfed the llrong exprcflion, that the air was peftilential and the water poifonous. Yet the country is everywhere fo verdant, gay, and fertile ; it is inter- fperfed with fuch magnificent houfes, gardens, avenues, canals, and draw-bridges ; and is fo formed in every re- fpeft to pleafe, could health be preferved in it — that a youth coming juft from fea, and enraptured with the beauty of every objeft he {d.v; around him, but mindful of the danger there to life, could not help exclaiming, "what an excellent habitation it would be for immortals!" The moft tolerable feafon here is from March or A- BAT [ 70 ] BEE r.-.tavh. pill to November ; wlien the ruins begin, and lall the ——^r^-' rtll of the year. The fea breeze fcts in about ten o'clock in the morning, and continues till four or five in the afternoon. It becomes then calm till feven or eir;ht, when the land breeze commences, and continues at intervals till day break, followed by a calm for the remaining hours of the 24. Fahrenheit's thermometer was, in Bata\ia road, during the Lion's remaining there, from 86^ to 8»°, and in the tov.-n from 88" to 92" ; but its variations by no means correfponded to the fenfa- tions produced by the heat on the human frame ; the latter l)eing tempered by Huy motion of the air, wiiicli circumftauce has little effeil upon the thermometer. Nor are the animal fuffcrings here from heat to be mea- fured by its intenfenefs at any given moment of the day, but by its perfiRing through the night ; when, in- ftead of dlminifhing, as it does in colder countries, fome- times 20 degrees, it keeps generally here within four or five of what it attains in the (liade, when the fun is at its highell elevation. The native Javanefc derive, however, one advantage at Icall from an atmofphere not I'ubjeft to the vicifli- tudes of temperature experienced in the northern parts of Europe, where difeafes of the teeth are chiefly pre- -valent ; as they are here entirely exempt from fuch com- plaints. Their habit of living chiefly on vegetable food, and of abllaining from fermented liquors, no doubt contributes to this exemption ; yet fuch is the caprice of talle, that jet black is the favourite colour and ftan- dard of beauty for the teeth amongft them, comparing to monkeys thofe who keep them of the natural colour. They accordingly take care to paint, of the deepeft black, all their teeth, except the two middle ones, which they cover with gold leaf. Whenever the paint or gild- ing is worn off, they are as attentive to replace It on the proper teeth, as the belles of Europe are to purify and M'hiten theirs. We have mentioned the rich vegetation of the coun- try and the gardens which the Dutch have planted. In thefe gardens or orchards they cultivate the nutmeg, the clove, the camphor, and the cinnamon trees, toge- ther with the pepper plant, which, creeping like a vine, is fupported on a living tree. It is a fpecies of the pepper plant that affords the leaf called betel, chewed fo unlverfvdly by the fouthern Afiatics, and ferving tor the inclofure of a few fliees or bits of the areca, from thence erroneoufiy called the hetel nut. The areca nut tree is among the fmallefl of the tribe of palms, but comes next in beauty to the mountain cabbage tree of the Welt Indies, the latter differing chiefly in its fize and amazing height from the areca nut tree, the diameter of whofe jointed trunk feldom exceeds four inches, or height 12 feet. But the fymmetry of each is perfedt ; the columns of a temple cannot be more regular than the trunk, 'which rifes without a branch, while the broad and fpreading leaves which crown the top form the orna- jnented capital. The areca nut, when dried, has fome fiinilltude in form and taife to the common nutmeg, but is of a lefs fize. It would have been very extraordinary, and very cul- pable, in Sir George Staunton, and Dr Glllan phyfician to the cmbafTy, if they had not, when on the fpot, in- quired into the truth of Foerfch's account of the upas ux poifon tree of Java (fee Poison Tree of Java, En- cycl.) But the moft minute inquiries were made re- fpefting it ; and the refnlt of them was, that no fuch tree is known at Batavia, and certainly does not exift where Foerfch has planted it. It is indeed a common ~ opinion at Batavia, that there exifts in that country a vegetable poifon, which, rubbed on the daggers of the Javanefe, renders the fllghtell wounds incurable ; though fome European praftitioners have of late afferted that they had cured perfons ftabbed by thofe weapons, but not without having taken the precaution of keeping the wound long open, and procuring a fuppuration. One of the keepers of the medical garden at Batavia affured Dr Gillan, that a tree dillilllng a polfonous juice was in that colleftion, but that its qualities were kept fecret from moll people in the fettlement, left the knowledge of them Ihould find its way to the flaves, who might be tempted to make an ill ufe of it. In the fame medical garden, containing it feems hurtful as well as grateful fubftanccs, is found alio the plant from whence is made the celebrated gout remedy, or moxa of Jaoan, men- tioned in the works of Sir William Tempk, and de- fcribed in the Encyclopsedia under the titles of Arte- misia and Moxa. The whole country abounds with efculent fruits, and, amonfl others, with the mangofleen, which is ripe in March, and is confidered as the moll delicious of all fruits (fee Garcinia, Encycl.) Pine apples are in Ja- va planted not in gardens, but In large fields ; and are carried like turneps In heaps upon carts to market, and fold for confiderably lefs than a penny each, where mo- ney is cheaper than In England. It was a common praftlce to clean fwords, or other Inllruments of fteel or Iron, by running them through pine apples, as con- taining the ftrongeil and cheapell acid for dlffolving the rull that covered them. Sugar fold for about five-pence a pound. All forts of provifions were cheap, and the fhlps crews fed on frefh meat every day. The ferpents and noxious reptiles In Java have been mentioned elfewhere ; but Sir George Staunton affures us, that not many accidents happen from them. Among the pag.^n Javanefe, the crocodile, he fays, is an objett not only of fear, but alfo of religious veneration, to which offerings are made as to a deity. When a Java- nefe feels himfcif dlfeafcd, he will fometlmes build a kind of coop, and fill it with fuch eatables as he thinks moft agreeable to the crocodiles. He places the coop upon the bank of the river or canal, in the perfeft con- fidence that, by the means of fuch offerings, he will get rid of his complaints ; and perfuaded, that if any per- fon could prove fo wicked as to take away thofe viands, fuch perfon would draw upon himfelf the malady for the cure of which the offering was made. According to Sir George Staunton, Batavia road lies In 6" lo' fouth lat. and 106° jl' eaft long, from Greenwich. BEER Is a liquor fo palatable to the natives of Bri- tain, and, when properly made, fo wholefome, elpeclally in long voyages at fea, that Mr Thornton of Eaft Smithfield obtained a patent, dated April 15. 1778, for inventing a method of reducing mult and hops to an elTence or extract, from which beer may be made any- where, either at fea or In diltant countries. Though we do not perceive any great degree of ingenuity dil- played In this Invention, yet as the account of it is fhort, we fhall lay It before our readers. His method then of preparing an effence or extraft of malt and hops is, by the tranfmitteJ heat of com- preiTed Batavia Beer BEE prelTed vapour of boiling water, and a proper apparatus ' for that purpofe. This apparatus may be made of iron, tin, or copper : it confifts of a boiler of any dimcnfions, a double vcfTel, and condudting tubes. The double vef- fel confills of one vcflel placed within another, and fitted tight at their rims. The upper veflel forms the upper part of the under veflel, and contains the liquor to be evaporated. The under veflel is everywhere inclofed except at an aperture communicating with the boiler, and at another aperture communicating with the con- ducing tubes ; and is conft;rufted fo as not to allow any part of the vapour condeufed into drops within it to efcape, except back again into the boiler : it is not fo cxtenfive as to aft as a common refrigeratory, and yet is capacious enough to prevent the liquor boiling over. The aperture communicating with the boiler is large enough to freely admit the vapour from the boiler into the under veflel ; and tlie aperture communicating with the condufting tubes is of a proper fize to allow of the vapour in the under veflel being comprefled, to a degree capable of tranfmittirig to the liquor to be evaporated a proper heat, and at the fame time to ferve as a paflage for more heat than is neceflary to keep up that degree of compreffion. The condutting tubes are to convey this fuperfluous heat or vapour, to be ufed for farther purpofes, or immediately out of the build- BEETLE, an infeft defcribed in the Encyclopedia under the name given to it by naturalifts, Scarab.eus. Since that aticle was publiflied, we have met with an account of a nondefcript fpecies, vvihich is furniflied with very Angular armour for its own defence. It was brought to M. Vaillant in the interior parts of Africa by a Nimiqua woman, and is by him called a fuperb beetle, not to be found in any cabinet of Europe. " While I was examining this beautiful infeft (fays he) with attention, I felt my face fuddenly wetted by a cauf- tic liquor, of a very ftrong alkaline fmcll. The fprink- ling wa-s accompanied by a fort of explofion, loud enough to be heard at fome diftance. Unfortunately fome of the liquor entered one of my eyes, and occafioncd fuch infupportable pain, that I thought I fhould have loft; the fight of it. I was obliged to keep it covered' for feveral days, and bathe it from time to time with milk. In every part of my face that the alkaline liquor had touched, I felt the pain of a burn; and everywhere the flcin changed to a deep brown, which wore out only by degrees and a long time after. This will not be furpri- fing to many, who already are acquainted with the fame property in feveral infefts of the fame genus ; for Jn- ftance, in that beautiful golden green bupreftis, which is fo common in our kitchen gardens in Europe : but as the infeft of which I am here fpeaking is much lar- ger, and inhabits a very hot country, it is natural that the effeA produced by it fliould be more linking ; tho' the liquor which our golden bupreftis ejefts at its enemy 71 ] B E H occafions a very fenfible fmart, and its fme'l Is confider- ably pungent." The naturaliils Dorci and Olivier have given. In their , Entomology, the figure of this African infcft, which our author communicated to them, hut they have given it erroneoufly. The human face, obfervable on its an- terior corctlet in their figure, does not exift in nature ; but M. Va'lhmt having given no figure of it himfelf, we cannot gratify our readers with a correft reprefen- tation. BEGAH, a land meafure in Bengal, about one-third of an Englifh acre. BEHADER fFallanl), a title of honour conferred by the Mogul emperors upon either Mahomedans or Hindoos, and placed after their name or other title. BEHEM (Martin), though hitherto little talked of, was one of the moll euterprifing men that ever lived, and deferves to have his name tranfmitted with reve- rence to the latefl; pofterity. Born at Nuremberg, an Imperial city in the circle of Franconia, of a noble fa- mily not yet extin£l, he had the beft education which the darknefs of that age would permit him to have ; and the ftudies to which from his infancy he was mod addifted, were thofe of geography, aftronomy, and na- vigation. As he advanced in life, he often thought of the exiftence of the antipodes and of a weftern conti- nent, of which he was ambitious to make the difco- very. Filled with this great idea, in 1459 he paid a vifit to Ifabella, daughter of John I. king of Portugal, at that time regent of the duchy of Burgundy and Flan- ders ; and having informed her of his defigns, he pro- cured a veflel, in which, failing weftward, he was the firit European who is known to have lauded 011 the Ifland ot Fayal. He there eft;abliftied in 1460 a colony of Fle- mings, whofe defcendants yet exift in the Azores, which were for fome time called the Flemilh Iflands. This cir- cumftance Is proved, not only by the writings of con- temporary authors, but alfo by the manufcripts prefer- ved in the records of Nuremberg ; from the Latin of which the following Is tranflated : "Martin Behem ten- dered his fervices to the daughter of John king of Lu- fitania, who reigned after the death of Philip of Bur- gundy, furnamed the Gooii ; and from her procured a flilp, by means of which, having failed beyond all the then known limits of the Wellern Ocean, he was the firft; who in the memory of man difcovered the ifland of Fayal, abounding with beech trees, which the people of Lufitania call _/(7yf ; whence it derived Its name. Af- ter this he difcovered the neighbouring iflands, called by one general name the A%or<-s, from the multitude of hawks which build their nefts there (for the Lufitanians ufe this term for hawks, and the French too ufe the word ejfos or efores in their purfuit of this game) ; and left colonies of the Flemilh on them, when they began to be called Flemlfli Iflands (a)." After BcgaU II Behem. (a) Although this record Is contrary to the generally received opinion, that the Azores were difcovered by Gonfalva Velho, a Portugucfe, yet its authenticity feems unqueftionable. It is confirmed not only by feveral contemporary writers, and by Wagenfeil, one of the moft learned men of the laft century, but likevvife by a note v/ntten on parchment in the German language, and fcnt from Nuremberg, a few years ago, to M. Otto, who was then mveftigating the difcovey of America. The note contained, with other things, the following facts: " Mar. tin Beham, Efq; fon of Mr Martin Beham of Scoperin, lived in the reign of J(,hn II. king of Portugal, in aa; ifland which he difcovered, and called the ifland of Fayal, one of the Azores, lying in the Weftern Oceim.. B E H [ 72 ] B E H Buhem. After having obtained from tin: regent a grant of ^~~*''~*'' Fayal, and refidcd there about twenty years, Behcm applied in 1484 (eijjht years before Columbus's expe- dition) to John II. king of Portugal, to procure the means of undertaking a great expedition towards the fouth-weft. This prince gave him fomc fliips, witii which he difcovered that part of America which is now called Brazil ; and h: even failed to the Straits of IVIa gellan, or to the country of fome favage tribes whom he called Patagoiiians, from the extremities of their bo- dies being covered with a flcin more like a bear's paws than human hands and feet. A fa6t fo little known, and apparently fo derogatory to the fame of Columbus, ought not to be admitted without fufficient proof; but the proofs which have been urged in fupport of its authenticity are fuch as cannot be controverted. They are not only the letters of Behem himfelf, written in i486, and preferved in the archives of Nuremberg, but hkewife the public re- cords of that city ; in which we read that " Martin Behem, traverfing the Atlantic Ocean for feveral years, examined the American iflands, and difcovered the ftrait which bears the name of Magellan before either Chrif- topher Columbus or Magellan failed thofe feas; whence he mathematically di'ineated, on a geographical chart, for the king of Lufitania, the fituation of the coall a- round every part of that famous and renowned ftrait long before Magellan thought of his expedition." This wonderful difcovery has not efcaped the notice of contemporary writers. The following patTage is tranflated from the Latin chronicle of Hartman Schedl: " In the year 1485, John II. king of Portugal, a m.tn of a magnanimous fpirit, furnifhcd fome galleys with provifions, and fent them to the fouthward, beyond the Straits of Gibraltar. He gave the command of this fquadron to James Canus, a Portuguefe, and Martin Behem, a German of Nuremberg in Upper Germany, defcendcd of the family of Boima : a man very well ac- quainted with the fituation of the globe ; bleffed with a conftitution able to bear the fatigues of the fea ; and who, by adual experiments and long failing, had made himfelf perfedlly mafter with regard to the longitudes and latitudes of Ptolemy in the weft. Thefe two, by the bounty of Heaven, coafting along the Southern Ocean, and having croffed the equator, got into the other iiemifphere, where, facing to the eaftward, their ftiadovvs projefted towards the fouth and right hand. Thus, by their induftry, they have opened to us ano- ther world hitherto unknown, and for many years at- tempted by none but the Genoefe, and by them in vain. Having finifhed this cruize in the fpace of 26 months, they returned to Portugal with the lofs of many of their feamen by the vioL-nce of the climate." Befides tlu's evidence of the firft difcovery of America having been made by Behem, we find the following particulars in the remarks made by Petrus Mateus on the canon law, two years before the expedition of Co- lumbus : " Pr'tma navigat tones , &c. The firft Chriilian voyages to the newly difcovered iflands became frequent under the reign of Henry, fon of John, king of Lufi- tania. After his death Alphonfus V. profecuted the defign ; and John, who fucceeded him, followed the plan of Alphonfus, by the affiftance of Martin Behem, a very flcilful navigator; fo that in a fliort time the name ni Lufitania became famous ov«r the whole world." Cellarius, one of the moft learned men of his age, fayi exprefsly, " Bihuimeus non moilo. Sec. Bochm did nut. "" think it enough to furvey the ifland of Fayal, which he iirft difcovered, or the other adjacent iflands which th: Lufitamans call A-iores, and we, after the example of Birhm's companions, call FUm'iJh iflands, but advanced ftill farther and farther fouth, until he arrived at the re- moteft ftr;ut, tiirough which Ferdinand Magellan, fol- lowing his track, afterwards failed, and called it after his own name." All thefc quotations, which cannot be thought te- dious, fince they ferve to prove a fa£l almoft unknown, feem to denionftrate, that the firll difcovery of America is due to the Portuguefe and not to the Spaniards; and that the chief merit belongs to a German allronomer. The expedition of Ferdinand Magellan, which did not take place before the year 1519, arofe from the follow- ing fortunate circumftance : Thi» perfun, being in the apartment of the king of Portugal, faw there a chart of the coaft of America drawn by Behem, and at once conceived the bold project of following the fleps of this great navigator. Jerome Benzoii, who publilhed a de- fcription of America in 1550, fpeaks of this chart ; a copy of which, fent by Behem himfelf, is preferved in the archives of Nuremberg. The celebrated aftronomer Riccioli, though an Italian, yet does not feem willing to give his countryman the honour of this important difcovery. In his Geographia Refarmata, book iii. p. 90. he fays, " Chriftopher Columbus never thonglit of an expedition to the Weft Indies until his arrival in the ifland of Madeira, where, amufing himfelf in forming and deliiicaling geographical charts, he obtained infor- mation from Martin Eoehm, or, as the Spaniards fay, from Alphonfus Sanches de Huelva, a pilot, who had chanced to fall in with the illand afterwards called Do- minka." And in another place: " Let Boehm and Columbus have each their praife ; they were both ex- cellent navigators ; but Columbus would never have thought of his expedition to America, had not Boehm goP-t there before him. His name is not fo much cele- brated as that of Columbus, Americus, or Magellan, although he is fuperior to them all." That Behem rendered fome very important fervices to the crown of Portugal, is put beyond all controverfy by the recompence bellowed on him by King John ; ot which the following account has been given to the pub- lic from the archives of Nuremberg. " In the year 1485, on the 18th of Feb. in Portugal, in the city of AUafa- vas, and in the church of St Salvador, after the mafs, Martin Behem of Nuremberg was made a knight, bv the hands of the moft piiiffant Lord John II. king of Portugal, Algarve, Africa, and Guinea ; and his chief fquire was the king himfelf, viho put the fword in his belt ; and the Duke of Begia was his fecond fquire, who put on his right fpur ; and his third fquire was Count Chiiftopher de Mda, the king's coufin, who put on his left fpur; and his fourth fquire was Count Mar- tini Marbarinis, who put on his iron helmet ; and the king himfelf gave him the blow on the flioulder, which was done in the prefence of all the princes, lords, and knights of the kingdom ; and he efpoufed the daughter of a great lord, in confideration ot the important fer-' vices he had performed ; and he was made governor of the ifland of Fayal." Thefe marks of dillindiion, conferred on a ftranger, could B E H [ 73 .1 . B E H Beliem. coulJ not be meant as a recompciico for the dlfcovery of ful objection to the truth of Bchem's claim to tlie dif- — 'r~— the Azores, which was made twenty years before, but covery of America ; for if it was really difcover<-d by '' as a rewrard for the dlfcovery of Congo, from whence him, wiiy did not he leave behind him fome writing to the Chevalier Behem had brought gold and diflerent confirm the dlfcovery to himfeli ? and why did not the kinds of precious w.ircs. This dlfcovery made much court of Portugal, fo jealous ot tlie dlfcovery of the greater impreflion than that of a wellern world made new worhl, protell againll the cxciufive claim ot tiic at the fame time, but which neither increafed the wealth Spaniards ? of the royal treafury, nor fatisfied the avarice of the To tliefe objeftlons we may reply, that, however merchants. plaufible they may at firll appear, they do not in the III 1492 the Chevalier Behem, crowned with hon viz. Firfl. binomial J -f- ^/ 5, 2d binomial v' 1 8 -f- 4, 3d binomial »/ 2^ -\- it/ 18, 4th binomi.u 4 + •v/ 3, jth binomi;il /^Z 6 -f- 2, 6th binomial y' 6 -f v^ 2. Binomial Theorem. .See Algfbra, Chrip. Seft. iii. [Encycl. Vol. I.) ; and Inf.nlli StRiss, VI 1, (Vol. XVII.) The reader who wiflies for a fuller account of this famous theorem, may find it in Dr Hutton's Ma- thematical Trafts, Vol. I. BIRD CATCHiijG, is an art which, as it is praftifed by means of bird lime, nets, decoys, &c. has been fufli- ciently explained in the Encyclopxdia. But there is another method of catching birds alive, by means of a fufee or m-ujhet, which was invented by M. Vaillant du- ring his travels in Africa, and is fufficiently ingenious to dcferve a place here. It is as follows : Put a fmaller or larger quantity of powder into youi fufee according as circumflances may require. Imme- diately above the powder place the end of a candle of fufficient thicknefs, ramming it well down ; and then fill the barrel with water up to the mouth. When at a proper diflance you fire a mudiet thus loaded at a bird, you will only^un it by watering and moillening its feathers; and if you be alert, you may cafily lay Mr Bezout lived in this employment for feveral years, hold of it before it have time to fpoil its plumage by beloved of his family and friends, and refpeded by all, fluttering. Our author admits, that in his firft attempts enjoying the fruit? and the credit of his labours. But the he often put too much powder, or too thick a piece of trouble and fatigues of his offices, with fomeptrfonal cha grilles, had reduced his ftrength and conilitution ; lie was attacked by a malignant fever, of which he died Sept. 27. 1783, in the 54th year of his age, regretted by his fa- mily, his friends, the young Undents, and by all his ac- quaintance in general. The books publiflied by him were : i. Courfe of Mathematics for the ufe of the Marine, with a Trea- tife on Navigation, 6 vols in 8vo, Paris, i 764. 2. Courfe of Mathematics for the Corps of Artillery, 4 vols in 8vo, 1770. 3. General Theory of Algebraic Equa- tions, 1779. His papers printed in the volumes of the Memoirs of the ."Academy ot Sciences are: i. On curves, whofe verification depends on a given quantity, in the volume for 1758. 2. On feveral clafles of equations that admit of an algebraic folution, 1762. 7,. Firil volume of a courfe of mathematics, 1764. 4. On certain equations, &c. 1764. 5. General refolution of all equations, 1765. 6. Second volume of a courfe of mathematics, 1765. 7. Third volume of the fame, 1766. 8. Fourth volume of the fame, 1767. 9. Intergration of differentials, &c. vol. 3. Sav. Etr. 10. Experiments on cold, 1777. BINOMIAL, a quantity confiding of two terms or members, conncfted by either of the figns -}- and — . See Algebra, def. 9. Encycl. Impojfible or Imaginary JBiuoMiJi, is a binonaial-which powaer, or too tlucK a pn candle into his fufee, or fired at too (hort a diftance ; aiifl when any one of thefe miftakes was committed, he generally found the candle entire in the animal's hi^ly ; but after a Ihort apprenticefhip he acquired fufficient (] appropriate to poetry, at kaft to all thofe lighter fpe- cies which rather depend on quicknefs of feeling, and the ready conception of pleafnig images, than on the happy arrangement of parts, or the (Icilful conflrudtlon of a whole, which are effential to the higher departments of the poetical art. The firft kind of talent is like thofe warm and light foils which produce their annual crops in fuch abundance ; the lalt, like that deeper and firmer mould on which the roots of eternal foreds are fixed. Of the firit we liave feen many happy in- ftances in that fex vvhicli is fuppofed lefs capable of ftudy or thought ; from the lall is drawn that mafcu- line fublimity of genius which could build an Iliad or a Paradife l.oft. Dr Blacklock could never diftate till he ftood up ; and as his bllndnefs made walking about without af- fiftance inconvenient or dangerous to him, he fell infen- fibly into a vibratory fort of motion of his body, which incrcafed as he warmed vvitli his fubjcft, and was plea- fed with the conceptions of his uiind. This motion at lad became habitual to him; and though he could fome- times reftrain it when on ceremony, or on any public appearance, fuch as preaching, he felt a certain uncafi- nefs from the effort, and always returned to it when he could without impropriety. This appearance he de- fcribes in a fliort poem, in which he gives a ludicrous pifture of himfelf ; a pifture indeed, of which, though the outlines are true, the general effeft is greatly over- charged. Though his features were hurt by the dif- So ] B L A cafe whitli deprived him of fight, there was a ccitain B!aAI(.,It. placid exprefiion in his countenance, which marked the ' " v~— ' benevolence of his heart, and was calculated to procure to him individual attachments and general regard. la 1762 he married Mifs liarah Johnfton, daughter of Mr Jofeph Johnfton iurgeon in Dumfries ; a con- nexion which formed the great folace and bkrTuig of his future life, and gave him, with all the tendernels of a wife, all the zealous care of a guardian and a friend. This event took place a few days before his being or- dained minifter of the town and parifh of Kircudbright, in confequence of a prefcntation from the crown, ob- tained for him by the earl of Selkirk, a benevolent no- bleman, whom Mr Blacklock's fituation and genius had interefted in his behalf But the inhabitants of the parifh, whether from that violent averfion to patronage, which was then fo univerfal in the fouthern parts of Scotland, from fome political dlfputes which at that time fubfiftcd between them and his noble patron, or from thofe prejudices which fome of them might natu- rally enough entertain againft a paftor deprived of fight, or perhaps from all thefe caufes united, were fo extreme- ly difinclincd to receive him as their minifter, that after a legal difpute of nearly two years, it was thought ex- pedient by his friends, as it had always been wlftied by Inmfelf, to compromife the matter, by refigning his right to the living, and accepting a moderate aimuity in its ftead. With this flender provifion he removed in I 764 to Edinburgh ; and to make up by his induftry a more comfortable and decent fubfiftence, he adopted the plan of receiving a certain number of young gentle- men as boarders into his houfe, whofe ftudics in langua- ges and philofophy he might, if necelfary, aflift. In this fituation he continued till the year 1787, when he found his time of life and ilate of health required a de- gree of quiet and repofe, which induced him to difcon- tinue the receiving of boarders. In 1 767 the degree of doftor in divinity was conferred on him by the univerii- ty and Marifchal college of Aberdeen. In the occupation which he thus exercifed for fo ma- ny years of his life, no teacher was perhaps ever more agreeable to his pupils, nor mafter of a family to its in- mates, than Dr Blacklock. The gentlenefs of his man- ners, the benignity of his difpofition, and that warm in- terell in the happinefs of others which led him fo con- ftantly to promote it, were qualities that could not fail to procure him the love and regard of the young people committed to his charge ; while the foclety, which efteem and refpeft for his charafter and his genius often afTembled at his houfe, afforded them an advantage rare- ly to be found in eftablifirments of a fimilar kind. In this mixed foclety he appeared to forget the pri- vation of fight, and the melancholy which it might at other times produce in his mind. He entered, wit'h the cheerful playfulnefs of a young man, into all the fpright- ly narrative, the fportful fancy, and the humorous jeil that rofe around him. Next to converfation, mufic was perhaps the fource of his greateft delight ; for he not only reliftied it highly, but was himfelf a tolerable per- former on feveral inftruments, particularly the flute. He generally carried in bis pocket a [mzW JlageoUt, on which he played his favourite tunes ; and was not dif- pleafed when aflced in company to play or to fing them ; a natural feeling fur a blind man, who thus adds a fcene to the drama of his fociety. Of B L A [ 8 cllock. Of the liappinefs of others, however, we are incom- ->t~~' petent judges. Companionfhip and fympathy bring forth thofe gay coloms of mirth and cheerfnlnefs which they put on for a while, to cover perhaps that fadntfs which we have no opportunity of witnefling. Of a bh'nd man's condition we are particularly liable to form a mil- taken eftimate ; we give him credit for all thofe gleams of delight which fociety affords him, without placing to their full account thofe dreary moments of darkfome folitude to which the fufpenfion of that fociety condemns him. Dr Blacklock had from nature a conilitution de- licate and nervous, and his mind, as is almoft always the cafe, was in a great degree fubjeft to the indifpofition of his body. He frequently complained of a lownefs and depreffion of Ipirits, which neither the attentions of his friends, nor the unceafing care of a moll affetf ionate wife, were able entirely to remove. The imagination we are fo apt to envy and admire ferves but to irritate this diforder of the mind ; and that fancy in whofe cre- ation we fo much delight, can draw, from fources un- known to common men, fubjefts of difgull, difquietude, and affliftion. Some of his later poems exprefs a cha- grin, though not of an ungentle fort, at the fuppofed failure of his imaginative powers, or at the faflidiouf- nefs of modern times, which he defpaired to pleafe. " Such were his efforts, fuch his cold reward, •' Whom once thy partial tongue. pronounc'd a bard ; " Excurfive, on the gentle gales of fpring, " He rov'd, whilll favour imp'd his timid wing; *' Exhaufted genius now no more infpircs, " But mourns abortive hopes, and faded fires; " The fliort-liv'd wreath, which once his temples grac'd, " Fades at the fickly breath of fqueamifh talle ; •' Whilll darker days his fainting flames immure " In cheerlcfs gloom and winter premature." Thefe lines are, however, no proof of " exhaufted genius," or " faded fires." " Abortive hopes," indeed, muft be the lot of all who, like Dr Blacklock, reach the period of old age. In early youth the heart of every one is a poet ; it creates a fcene of imagined hap- pinefs and delufive hopes ; it clothes the world in the bright colours of its own fancy ; it refines what is coarfe, it exalts what is mean ; it fees nothing but diiintcrcll- edneis in frieudfhip ; it promiles eternal fidelity in love. Even on the dillrctfes of its fitnation it can throw a certain romantic (liade of melancholy that leaves a man fad, but does not make him unhappy. But at a more advanced age, "the fairy vilions fade," and he fuffers moft deeply who has indulged tlrem the moft. About the time that thefe verfes were written, Dr Blacklock was, for the firft time, afflifled with what to him mull have been peculiarly diftrefsful. He became occafionally fubjeft to deafnefs, which, though he fel- dom felt it in any great degree, was fufScient, in his fi- tuation, to whom the fenfe of hearing was almoft the » only channel of communication with the external world, to caufe very lively uneafmefs. Amidll thefe indifpo- fitions of body, however, and difquietudes of mind, the gentlenefs of his temper never forfook him, and he felt all that refignation and confidence in the Supreme Be- ing which his earlieft and his lateft life equally acknow- ledged. In fummer 1791 he was feized with a feverifh diforder, which at firft feemed of a flight, and never rofe to a very violent kind j but a frame fo little robuft as SuppL, Vol. I. Part I. I ] B L A his was not able to refift it, and after about a week's illnefs it carried him off on the 7th day of July 1791. '' His wife furvlves him, to feel, amidft the heavy afflic- tion of his lofs, that melancholy confolation which is derived from the remembrance of his virtues. The writings of Dr Blacklock confiftc-d principally of poems, which were publiflicd in 410 in the year 1 792 ; and to that edition was added. An FJfay on the Eriuca- tion of the Blmd, tranjlaled from the Ficnch of M. Hauy. But befides his avowed works, we have reafon to be- lieve that he was the author of many articles in the fe- cond edition of the Encyclopedia Britannica, though we cannot fay with certainty what thofe articles were. If our memory does not deceive us, we have been inform- ed that the preface to that edition was furnilhed by him ; and we have elfewhere attributed to him, on the beft authority, the article Blind, and the Notes to the article Music : but he undoubtedly contributed much more to the work, and was one of the principal guides of the proprietors. BLAIR (Dr Hugh), was born in Edinburgh, on the 7th day of April 1718. His father, John Blair, a refpedable merchant in that city, was a defcendant of the ancient family of Blair in Airlhire, and grandfon of the famous Mr Robert Blair minifter of St Andrew's, chaplain to Charles I. and one of the moft zealous and diftinguiflied clergymen of the period in which he li- ved. This worthy man, though firmly attached to the caufe of freedom, and to the Prefbyterian form of church government, and though aftively engaged in all the meafures adopted for their fupport ; yet, by his fteady, temperate conduc't, commanded the refpeft even of his opponents. In preference to all the other eccle- fiaftical leaders of the covenanting patty, he was feleA- ed by the king himfelf to fill an office which, from the circumftances of the time, gave frequent accefs to the royal perfon ; " becaufe (faid his majefty) that man is pious, prudent, learned, and of a meek and moderate calm temper." His talents feem to have defcended as an inheritance to his pofterity. For of the two fona who furvived him, David, liie cldeft, was a clergyman of eniinence in Edinburgh, father to Mr Robert Blair mir.ifter of Athclftonford, the celebrated author of the poem intitled The Grave ; and grandfather to his ma- jefty's fdicitor general for Scotland, whofe mafculine eloquence and profound knowledge of law have, in the public eftimation, placed him indifputably at the head of the Scottiih bar. From his youngell fon Hugh, who engaged in bufinefs as a merchant, and had the honour to fill a high ftation in the magiftracy of Edin- burgh, fprung tiic learned clergyman who is the fub- jeCl of this narrative. The views of Dr Blair, from his earlieft youth, were turned towards the charch ; and his education received a fuitable diredion. After the ufual grammatical courfe at fchool, he entered the humanity clal's in the univer- fity of Edinburgh in Oftober 1730, and fpent eleven years at that celebrated feminary, alTiduoufly employ- ed in the literary and fcientific ftudics prefcribed by the church of Scotland to all who are to become can- didates for her licence to preach the gofpel. During this important period, he was diftinguiftied among his companions both for diligence and proficiency ; and ob- tained from the profcfTors under whom he ftudied re- peated teflimonics of approbation. One of them de- li fervei Bla B L A [8. Blair, {erves to be mentioned particularly, bfcaufe, in his own ""~v^— ' opinion, it determined tlic bent of bis genius towards polite literature. An effay "'?■ '■»" "">-""• or, On the Beau- tiful, written by him when a Undent of logic in the ufual courle of academical cxercilef, had the good fortune to attraft the notice of profeiT.ir Stevenfon, and, with cir- cumilances honourable to the author, was appointed to be read in pnblic at the conclufion of the term or fei- fion. This mark of diftinftion made a deep impreflion on his mind; and the elfay which merited it he ever after recoUefled with partial afFeftion, and preferved to the day of his death as the firft earned of his fame. At this time Dr Blair commenced a method of fludy which contributed much to the accuracy and extent of his knowledge, and which he continued to pradife oc- cafionally even after his reputation was fully eftabliflied. It confifted in making abftrafts of the moil important works which he read, and in digefting them according to the train of his own thoughts. Hiftory, in_ parti- cular, he refolved to ftudy in this manner ; and, in con- cert with fome of his youthful aflbciates, he conilrufted a very comprehenfive fcheme of chronological tables, for receiving into its proper place every important faft that fhould occur. The fcheme devifed by this young ftu- dent for his own private life was afterwards improved, filled up, and given to the public by his learned friend Dr John Blair, prebendary of Weilminller, in his va- luable work, " The Chronology and Hiftory of the World." Tn the year 1739, Dr Blair took his degree of A.M. On that occafion he printed and defended a thefis, De Fundamenlis et Obligatione Lcgis Nature, which contains a ihort but mafterly difcuffion of this important fubjeft, and exhibits in elegant Latin an outline of the moral principles which have been fince more fully unfolded and illuftrated in his Sermons. The univerfity of Edinburgh, about this period, numbered among her pupils many young men who were foon to make a diftinguifhed figure in the civil, the ecclefiaftical, and the literary hiftory of their coun- try. With moft of them Dr Blair entered into habits of intimate connedion, which no future competition or iealoufy occurred to interrupt, which held them united "through life in their views of public good, and which had the moft beneficial influence on their own improve- ment, .on the progrefs of elegance and tafte among their contemporaries, and on the general interefts of the community to which they belonged. _ On the'completion of his academical courfe, he un- derwent the cuftomary trials before the prefbytery of Edinburgh, and received from that venerable body a licence to preach the Gofpel on the ziftofOdober I 741. His public life now commenced with very fa- vourable profpeds. The reputation which he brought from the univerfity was fully juftified by his firft ap- pearances in the pulpit ; and, in a few months, the fame of his eloquence procured for him a prefentation to the parilh of Coleflie in Fife, where he was ordained to the office of the holy miniftry onthe 2 ^d of September 1742. But he was not permitted to remain long in this rural retreat. A vacancy in the fecoud charge of the Canon- gate, a fuburb of Edinburgh, furniihed to his friends an opportunity of recalling him to a ftation more fuited to his talents. And, though one of the moft popular and eloquent clergymen in the church wras placed in com- i ] B L A petition with him, a threat majority of the eledors de- cided in favour of this young orator, and reftored him in July 1743 to the bounds of his native city. In this Ihnion Dr Blair continued eleven years, dif. charging with great fidelity and fuccefs the various du- ties of the paftoral oflice. His dlfcourfes from the pul- pit in particular attraded univerlal admiration. They were computed with uncommon care ; and, occupying a middle place between the dry metaphyfical difcuffion of one clals of preachers, and the loofe incoherent de- clamation of another, they blended together, in the happleft manner, the light of argument with the warmth of exhortation, and exhibited captivating fpecimens of what had hitherto been rarely heard in Scotland, the pohihed, well-compaded, and regular didadic oration. In confequeuce of a call from the town-council and general-feffion of Edinburgh, he was tranflated from the Canongate to Lady Ycfter's, one of the city churches, on the nth of Odober 17J4: and on the 15th day of Jure 1758, he was promoted to the High Church of Edinburgh, the moft important ecclefiaftical charge in Scotland. To this charge he was railed at the re- queft of the Lords of Council and Seffion, and of the other diilinguirtu'd official charaders who have their feats in that church. And the uniform prudence, abi- lity, and fuccefs, which, for a period of more that forty years, accompanied all his minifterial labours in that confpicuous and difficult ftation, fufficiently evince the wifdom of their choice. Hitherto his attention feems to have been devoted al- moft exclnfively to the attainment of profeffional excel- lence, and to the regular difcharge of his parochial du- ties. No produdion of his pen had yet been given to the world by himfelf, except two fermons preached on particular occafions ; fome tranftations, in verfe, of paf- fages of Scripture for the pfalmody of the church; and a few articles in the Edinburgh Review ; a publica- tion begun in 1751;, and conduded for a fliort time by fome of the ablell men in the kingdom. But ftanding as he now did at the head of his profeffion, and releafed by the labour of former years from the drudgery of vieekly preparation for the pulpit, he began to think ferioufly on a plan for teaching to others that art which had contributed fo much to the eftablifhment of his own fame. With this view, he communicated to his friends a fcheme of ledures on compofition ; and ha- ving obtained the approbation of the univerfity, he be- gan to read them in the college on the nth of Decem- ber 1759. To this undertaking he brought all the qualifications requifite for executing it well; and along with them a weight of reputation, which could not fail to give effed to the leftbns he fhould deliver. For, be- fides the teftimony given to his talents by his fucceffive promotions in the church, the univerfity of St Andrew's, moved chiefly by the merit of his eloquence, had in June 1757 conferred on him the degree of D. D. a li- terary honour which at that time was very rare in Scot- land. Accordingly his firft courfe of ledures was well attended, and received with great applaufe. The pa- trons of the univerfity, convinced that they would form a valuable addition to the fyftem of education, agreed in the following fummer to inftitute a rhetorical clafs, un- der his diredion, as a permanent part of their academi- cal eftablifhment : and on the 7th of April 1762, his Majefty was gracioufly pleafcd " to ered and endow a pro. B!i-r B L A [ 83 ] B L A profefToifhip of rlietonc and belles lettres I'n the uiiiver- ■* iky of Edinburgh ; and to appoint Dr Blair, in confi- deratiiHi of liis approved qualifications, regius profeffor thereof, with a falary of L.70." The leftures which he read as profefTor of rhetoric, he publifhed in 1783, when he retired from the labours of the office ; and the ge- neral voice of the public has pronounced them to be a moft judicious, elegant, and comprehenfive fyllem of rules for forming the ilyle and cultivating the tafte of youth. About the time in which he was occupied in laying the foundations of this ufeful inftitution, he had an op- portunity of conferring another important obligation on the literary world, by the part which he afted in ref- cuing from oblivion the poems of Ofiian. It was by the iolicitation of Dr Blair and Mr John Home, that Mr Macpherfon was induced to publiih his Fragments of Ancient Poetry ; and their patronage was of efTential fer- viee in procuring the fubfcription which enabled him to undertake his tour through the Highlands for col- lefting the materials of Fingal, and of thofe other de- lightful produftions which bear the name of Offian. To thefe produdlions Dr Blair applied the tell of ge- nuine criticifm ; and foon after their publication gave an ellimate of their merits in a Di/ferlatlon, which, for beauty of language, dehcacy of taile, and acutenefs of critical inveftigation, has few parallels. It was printed in 1 763, and fpread the reputation of its author through- out Europe. The great objefts of his literary ambition being now attained, his talents were for many years confecrated folely to the important and peculiar employments of his llation. It was not till the year 1777 that he could be induced to favour the woild with a volume of the Ser- mons which had fo long furnifhed inftrucSlion and de- light to his own congregation. But this volume being well received, the public approbation encouraged him to pioceed : four other volumes followed at different intervals, the laft of which was publifhed after his death ; and all of them experienced a degree of fuc- ceis of which few publications can boaft. They circu- lated rapidly and widely wherever the Englifli tongue extends ; they were foon tranflated into almoft all the languages of Europe ; and his prefent Majeily, with that wife attention to the interefts of religion and lite- rature which diftinguiihes his reign, was gracioufly plea- fed to judge them worthy of a public reward. By a royal mandate to the Exchequer in Scotland, dated Ju- ly 25th 1780, a penfion of L.200 a-year was conferred on their author, which continued unaltered till his death. In that department of his profeffional duty which re- garded the government of the church, Dr Blair was lleadily attached to the caufe of moderation. From diffidence, and perhaps from a certain degree of inap- titude for extemporary fpeaking, he took a Icfs public part in the conteils of ecclefialUcal politics than fome of his contemporaries ; and, from the fame caufes, he never would confent to become moderator of the Ge- neral Aflembly of the Church of Scotland. But his influence among his brethren was extenfive: his opinion, guided by that found uprightncfs of judgment, which formed the predominant feature of his intcllcdual cha- rafter, had been always held in high refpett by the friends with whom he afted ; and, for many of the lali years of his life, it was received by them almoft as a law. The great leading principle in whicli tlicv ^r- ^ dially concurred with him, and which directed all thrir meafures, was to preferve the church, on the one fide, from a Oavilh, corrupting dcpendance on the civil power; and, on the other, from a greater infufion of democra- tical influence than is compatible with good order, and the eftablilhed conlb'tution of the country. The reputation which he acquired in the difcharge of his public duties, was well fuilained by the great re- fpedability of his private character. Deriving from family aflbciations a ftrong fenfe of clerical decoium, feeling on his heart deep impreffions of religious and moral obligation, and guided in his intercourfe with the world by the fame corrctl and delicate tade which appeared in his writings, be was eminently dillinguilhcd through life by the prudence, purity, and dignilied pro- priety of his conduCl. His mind, by conftitntion and culture, was admirably formed for enjoying happinefs. Well balanced in itfelf by the nice proportion and ad- juft;ment of its faculties, it did not incline him to any of thofe eccentricities, either of opinion or of aftion, which are too often the lot of genius : — free from all tinClure of envy, it delighted cordially in the profperity and fame of his companions : fenfible to the ellimation in which he himfelf was held, it difpofed him to dv.'ell at times on the thought of his fuccefs with a fatisfac- tion which he did not affeCl to conceal : inacceifible ahke to gloomy and to peevifli impreffions, it was aU ways mailer of its own movements, and ready, in an uncommon degree, to take an aifive and pleafing in- terell in every thing, whether important or trifling, that happened to become for the moment the objeft of his attention. This habit of mind, tempered with the moil unfufpefting timplicity, and united to eminent talents and inflexible integrity, while it fecured to the laft his own reliih of life, was wonderfully calculated to endear him to his friends, and to render him an invalu- able member of any fociety to which he belonged. Accordingly there have been few men more univerfally refpedted by thofe who knew him, more fincerely eileemed in the circle of his acq\iaintance, or more ten- derly belo-Ked by thofe who enjoyed the bkffing of his private and domeflic connexion. In April 1748, he married his coufin Katharine Bannatine, daugluer of the Rev. James Bannatine, one of tlie miniilers of Edinburgh. By her he Had a fon who died in infancy, and a daughter who lived to her twenty-firft year, the ])ridc of her parents, and adorned with all the accomplifliments that became her age and fex. Mrs Blair herfelf, a woman of great good fenfe and fpirit, was alfo taken from him a few years before his death, after fhe had Ihared with the tenderell aff'cc- tion in all his fortunes, and contributed near half a cen- tury to his happinefs and comfort. Dr Blair had been naturally of a feeble conftitution of body ; but as he grew up his confl.itution acquired greater tirmnefs and vigour. Though liable to occa- fional attacks from I'ome of the fliarpelt and molt pain- ful dileafes that afiliCf the human frame, he enjoyed a general ftate of good health ; aud, through habitual cheerfulnefs, temperance, and tare, furvived the ufual term of human life. — For fome years he had felt him- felf unequal to the fatigue of inllrufting his very large congregation from the pulpit ; and, under the inipreffion L 2 which Bh Bhir, Bleaching. B L E [ 84 ] B L E which this feeling produced, he has been heard at times air rufhes out forcibly; the receiver mud be quickly Bl'-'^etiing: to fay with a iigh, " thiit be was left almoll the laft of flopped, and another applied. Thus many receivers *"~~v-~" * Blair', SermonSy vol. V. his contemporaries." Yet he continued to the end in the regular diicharge of all his other official duties, and particularly in giving advice to the afflicted, who, from diifercnt quarters of the kingdom, folicited his corre- fpondence. His laft fummer was devoted to the pre- paration of the laft volume of Ins fermous ; and, in the courfe of it, he exhibited a vigour of underftandiug and capacity of exertion equal to that of his bcft days. Ho may be filled with the dephlogifticated muriatic acid ; but it is neceffary to place the retort in fuch a manner that the drops which rife into its neck may be able to fall back. The water fcrves to retain the vapours of the acid. " I ule (fays he) many receivers, that I may not be obliged to repeat a limilar dillillation for every experiment. It is not proper to employ large ones, becaufe every time they are opened a great part of the began the winter pleafed with himfclf on account of acid is diffipated in the air. What I fubmitted to ex- tlie completion of this work ; and his friends were flat- tered with the hope that he might live to enjoy the ac- celfion of emolument and fame which he expected it woidd bring. But the feeds of a mortal difeafe were lurking unperceived within him. On the 24th of De- cember i8?o, he complained of a pain in his bowels, which,, during that and the following day, gave him but little unealinefs ; and he received as ufual the vifits of his friends. On the afternoon of the 26th, the lymp- toms became violent and alarming : — he felt that he was approaching the end of his appointed courfe : and retaining to the laft moment the full poffeflion of his mental faculties, he expired on the morning of the 27th, with the conipofure aad hope which become a Chriftian paftor. The lamentation for his death was univerfal and deep through the city which he had fo long inftruCled and adorned. Its magiftratcs, participating in tlie general grief, appointed his church to be put in mourning ; and his colleague In It, Dr Finlayfon, from whom this ac- count of his life Is borrowed*, preached his funeral fermon. In which his charafter Is drawn In a mafterly manner, though with the almoft unavoidable partiality of friendftiip. If we, who know Dr Blair only In his writings, might prefume to eftimate his Intelleftual character, we (hould fay that he poffeflVd a found judgment rather than what could be called a vigorous mind ; that he had more tafte than genius ; and that he taught fuc- cefsfuUy, as far as It can be taught, the art of poetry, though he could not himfclf have been a poet. His moral character was amiable and refpeftable, though he feems, even from a hint dropt by his biographer, to have been in a flight degree tinftured with vanity. But this was furely a venial weaknefs ; for where is the aminatlon with this dephlogifticated muriatic acid was placed In the neck of the receiver, which I had ftopped. The cork was turned yellow as by aquafortis. Paper tinged with turnfol became almoft white; all red, blue, and yellow flowers, as alfo green planes, turned yellow in a fhort time, and the water in the receiver was chan- ged into pure but weak muriatic acid. Neither al- kalis nor acids were able to reftore the colours of the flowers, or of the plants." M. Berthollet, In 1785, proved that this acid was compofed of muriatic acid combined with oxygen ; and that when It had deprived vegetable matters of their co- lour, It was reduced to the ftate of common muriatic acid ; that is, it had loft the oxygen with which it was j united. Tills oxygen had combined with the colour- Its applica. Ing particles of the vegetable matter, and had rendered ''<>" '<^ them colourlefs. After making thcfe obfervations. It "*""f'E' occurred to him that the oxy-murlatic acid might pro- duce the fame efFeft upon thofe particles which give colour to thread and cloth, and which it is the objedt of bleaching to deftroy. "At firft (fays he) I made ufe .4/hi. A of water highly Impregnated with this acid ; and 1 rt- Cl>im. II. newed It when it was exhaufted, until the thread or '5 • cloth appeared white ; but I foon perceived that they were confiderably weakened, and that they were en- tirely lofing their folldlty. I then weakened the liquor a little, and I fucceeded In bleaching cloth without da- maging it. But it fpeedily became yellow by keeping, efpecially if ft wi^ warmed, or paffed through an al- kaline ley. I r«lefted upon the circumftances of com- mon bleaching, and I endeavoured to Imitate its pro- cefs, becaufe I thought the oxygenated muriatic acid might aft in the fame manner ns the expofiiion of the cloth in the meadows, which alone does not futlice, but which appears only to difpofe the colouring parts of head that would be wholly unaffefted by the fumes of the cloth to be dlffolved by the alkali of the ley. 1 ex- Difcovei7 cf the oty. muriatic aciJ. incenle burnt before it for fifty years ? BLEACHING. Since the article Bkathing In the Encvclopasdia was written, very great Improvements have been introduced into the art. Of thele improve- m.ents we fliall proceed to give an account. Mr Scheele of Sweden difcovered the oxy-muriatic acid, or dephlogifticated muriatic acid, as he called it, about the year 1774, and foon after obferved Its effefts amined dew, not only that which falls trom the atmo- fphere, but alfo that which comes from the nocturnal tranfpiration of plants ; and I obferved that both of them were Impregnated with oxygen, fufBciently to de- ftroy the colour of paper flightly tinged with turnfol. " I therefore employed leys, and the aftion of oxyge- nated muriatic acid, alternately, and I then obtained a permanent white ; and as, at the finifliing of the com- on vegetable colours. His method of procuring It was mon bleaching, the cloth Is pafled through four milk, as follows : In a fand-bath Is to be placed a glafs re- or through fulphuric acid diluted with a very large quan- tort, in which muriatic acid has been poured upon man- tity of water, I alio tried paffing the cloth through a ganefe ; to this fmall receivers are to be adapted capa- very dilute folutlon of fulphuric acid, and I obferved ble of containing about twelve ounces each, into which that the white was thereby rendered more clear. As is to be poured about two drachms of water, without foon as I made ufe of the leys intermediately, I found any other lute than a flip of blotting-paper about the that it was not neceflary to employ a concentrated II- neck of the retort. In about a quarter of an hour a quor, or to let the cloth, at every Immerfion, remain yellow air is perceived in the receiver, which Is to be long therein : by this I avoided two Inconveniences, taken off. If the paper has been properly applied, the which would hav€ rendered this proccfs impoflible to be B L E [ 85 ] B L E leiching. be praftifed in the large way. Tlie fufl is the fulfoca- ter ; for if the evaporation (hould take place, the fiil. Bleaching. ■"V"" ting oJour of the hquor, which it would be very incon- phiiric atiJ, hecoiiiiiig thereby Lonctiitratcd, would cor- — ~v -' venient, and even dangerous, to refpire for any length rode them. The cloths being then well waflied, rc- of time, and which has difcouraged many perfons who quire only to be dried and drcfled in the ordinary man- tried to ufe it ; the fecond is, the danger of weakening ner, accordiiig to their different forts. the cloth. 1 now alfo left ol7 mixing any alkali with " It is of the utmoll importance to take care that the ' the oxygenated muriatic acid, as I had praitifed in the water is not too ilrongly impregnated with the lulphu- greatell part of my firft trials. ric acid. "Tliis is nearly the ttate in which my experiments " The bleaching of cotton cloth Is much ealler and were, when 1 made fome trials in the j>refence of the (horter ; two leys, or at mod three, and as many im- celebrated Mr Watt. A iingle view fufficed for a phi- merfions in the bleaching liquor, are fnfficient for them, lofopher wliofe genius has been exercifed fo long upon As they are bleached fo ealily, it is advantageous, when the arts. In a (liort time Mr Watt wrote to me from England, that even in the firll operation lie had bleach- ed live hundred pieces of cloth at Mr Grigor'i vho there are flaxen, hempen, and cotton cloths, to be bleached, to leferve for the cotton tlie litjuors which have been previoufly weakened by the clotlis of flax or has a large bleaching-ground at Glafgow, and who con- hemp; for it is economical to exhaull the li(|Uors as tinues to make ufe of the new procefs. In the mean much as poffible, and thofe which are coufidcrably time M. Bonjour, who had hitherto aflilled me in my weakened ftill fufKce for the cotton,, although they have experiments, and who joins great fagacity to a moil ex- fcarcely any aiftion upon hemp or flax, tended knowledge of chemillry, afl'ociated himfelf with " Thread, in the common way of bleaching, is attend- Mr Conftant, at Valenciennes, in order to form an tfta- ed with a far greater number of difficulties than cloth; blifliment in that city." becaufe of the immenfe number of furfaces which it is M. Caillau made a great number of experiments at necefTary to prefent fucceilively to the ailion of the at- Paris refpefting this new mode of bleaching ; but the mofphere. Some part of thefe difficulties occur in greateft part of thefe experiments was made upon cot- bleaching with the oxygenated muriatic acid; neverthe- ton, which is more eafy to bleach, and does not require lefs, in tlie end, it is more advantageous with 1 efpe33 Ihs. Clarke's refined afli - - 26,875 Caftiup - - 19)37^ Common ravr Irifli weed-afh 1,666 Ditto nightly calcined 4,666 When linen is allowed to remain for fome time in oxy-muriaric acid, it becomes white. It is evident, then, that when the colouring matter of linen is faturated with oxygen, it becomes colourlcfs : But linen bleach- ed in this manner very loon becomes yellow, efpecially when expofed to ht-at. Benhollct, to whofe ingenious experiments and obfervations we are indebted for the greater part of the above remarks, has given the fol. lowing explanation of the caiile of this change : He diftilled the colouring matter of linen, and obtained a thick oil, a little ammonia, and /j'*^ of carbon remain, ed behind. The oil contained carbon ; and he fuppo- fed that carbonic acid gas, and carbonated hydrogen gas, were difengaged. He concluded in confequence, that one-third of this colouring matter was carbon. The other ingredient in the oil was hydrogen ; for La- voilier has proved that oil is compofed of oxygen and hydrogen. The colouring matter of linen, then, is compofed principally of carbon and hydrogen. Oxygen combines with hydrogen at a lower tempe- rature than it does with carbon ; for if a confiderable quantity of oxy-muriatic acid be mixed with a folution of fugar (a fubftance which confills chiefly of carbon and hydrogen), and the liquor be evaporated, there remains behind little elfe than carbon, the hydrogen having combined with oxygen and formed water, which had paffed off in the form of vapour. Now, whenever a quantity of hydrogen is feparated from a body prin- cipally B L E [ 89 ] B L E Bleaching, cipally compofed of hydrogen and carbon, tliat body fpirit only wbich has been kept in veffels of glafs, of BlcacMngi ^—^ ' afTumes a brown or yellow colour, becaufe the carbon tinned copper, or of pure tin. Leaden velTels are abfo-*""*— ~* becomes predominant; and this colour becomes the lutely to bcrcjefted ; wooden vell'cls tinge the fpirit, deeper the greater the proportion of the carbon is, coin- which gives the filk a degree of colour of confiderable pared to that of the hydrogen ; and at lall, when no- permanency, and very inimical to the bleaching procefs, thinw but carbon remains, it becomes quite black. The filk is wound off upon a reel, v.hile the cocons It is probable, then, that when the oxy-rriuriatic a- are kept immerfcd in water almoll boiling. Upon tliis cid renders linen white, a quantity of oxygen has com- bined with the colouring particles; but that this oxy- gen gradually enters into a combination with the hy- drogen, arid forms water which palles oti; that then the carbon becomes predominant, and the linen in conle- * Ann Jr. qucnce afTuuies a yellow colour*. Cbim.Vl. -pfjg {mx~e method does not fucceed in bleaching * *- wool and filk which anfwers for linen and cotton. One Bkaching would be difpofed to think that thefe fiibllances are of wool and bleached rather by loling oxygen than by abforbing it. filk- Wool, for inftance, is rendered white very quickly when expofed to the fumes of fulphurous acid, which we know has a ftrong affinity for oxygen, and foon fatu- rates itfelf with it. But what pafles during the whiten- ing of animal matters has never yet been properly inquired into, though it would not only greatly eluci- date bleaching, but i!yeing likewife, and throw much light upon fome of the obfcureft parts of chemiftry. A great improvement, however, has htely been made by M. Baume in the manner of bleaching lilk. Of this improvement we (hall proceed to give an account f. Before the filk is wound off the cocons in which the Cb' "xv'' '"'"^ vvorms are enclofed, it is neceffary to kill the in- iSb. and a- fefts, otherwife they would in all probability eat thro' adhere, if wrung while wann for the purpofe of clearing jridgcd in it and dcllroy it. This is commonly done by expofing it of the water. After inch improper treatment there Nuhclfin s ji^g cocons, properly wrapped up, for two hours to the would be no other remedy than to foak it again in warm ii°"frrm ^'^'"- "^ about 158 degrees of Fahrenheit in an oven ; water. which lafl after which they are kept for a certain time in a mafs The apparatus for bleaching the filk confifts of a [vehaveta-to preferve their heat, and efTeftually dcftroy fuch of (lone ware veflel, nearly of a conical form, capable of lenourac-jijg infei^s as might have efcaped the power of the holding about 12 gallons, havhig a large opening at the "3 'oven. The effett of this procefs is, that the filk is New mode hardened, and is more difficult to wind off than before, if whiten- Hence the produft of filk is lefs by one ninth part in quantity, and inferior in quality to what might have been obtained by winding off without this previous ba- king. M. Baume, not only from thtfe views, but like- wife becaufe the filk which has not been baked proves fufceptible of a greater luftre, was induced to dcitroy the chryfalis by Ipirit of wine. For this pui-pofe he difpofes them in a wooden box in a ftratum fix inches \ See the memoir in part ot the procefs M. ]53ume remarks, I. That the dead cocons muil be feparated. Thefe are known by the brown or black fpots on their furface. 2. That wtllvvater, which on account of its clearnefs is almoll iiniverially ulcd in the filk manufattories, moftly con- tains nitre, and is extremely prejudicial to the bleaching procefs. The prefence of nitrous acid gives a yellow colour, which refills bleaching and even fcouring ; he therefore recommends river-water. 3. In fome coun- tries a fmall quantity of alum is ufed. Neither this nor any other faline fubilance is of the lead advantage to the colour, beauty, or quality of the filk. At the four places ot contaft of the filk upon the reel, all the threads (lick together. It is abfolulcly ne- cefl'ary that this (hould be remedied. The method con- fids in foaking the filk in a iufficlcnt quantity of v.drm water, at about g~> degrees, for about two hours ; a'ter which the threads are to he feparated by opening the hanks upon a pin, and lightly rubbing the parts which cohere. When the filk is dry, it is to be loofely folded in its original form, and is ready for bleaching. The filk while wet is foft, and part of its gummy matter is in fuch a (late, that its threads would readily iig filk. one end, and a fmaller of about an inch diameter at the other end. Common pottery cannot be ufed in this operation, becaufe it Is foon rendered unferviceable by the aflion of the muriatic acid, and the (lone-ware it(clf is not very durable. This vcfTel mud be carefully examined, to afcertain that it does not leak in the (lighted degree ; after which the infide is to be rubbed with a pumice-done, to clear it of afperities which might break the threads. A cover of the fame material is to be fit- ted on by grinding ; and the fmaller aperture, which \n deep : upon each fquare foot half a pint of fpirit of the ule is the lowed, is to be clofed with a good cork, wine is to be fprinkled with a fmall watering-pot made for that purpofe. The liquid is to be equally didribu- ted, but it is not neceffary that all the cocons (hould be wetted. They are then to be mixed by hand. In the next place another dratum is to be formed over the fird, nearly of the fame depth, which is to be fprinkled and treated as before. By this method of proceeding, the box becomes filled, and mud then be covered, and left for 24 hours; during which time they become fpon in the middle of which is thrud a fmall glafs tube about a quarter of an inch in diameter; this is likewife flop- ped witli a cork, excepting at the time when it is requi- red to draw off the liquid contents of the jar. A fmall perforated falfe bottom is placed within the velTel, to prevent this tube from being obdrufted. Six pounds of yellow raw filk are to be difpofed in the earthen pot ; upon this is to be poured a mixture, previoufly made, of 48 pounds of fpirit of wine of the taneoudy heated to about too degrees, and the vapour fpecific gravity .867, with 12 ounces of very pure ma- of the fpirit of wine exerts itfelf with wonderful aaring a '*ure mu- iatic acid. B L E But the alcuhol, every time it is Bleaching, ul'ed and reftified, becomes charged with the atid and '— — v— ' gas of nitre, which alTume the characters of the iiilious anodyne liquor. In this ftate neither diftillations nor repeated redlifications from alkali are fufficiciit to fepa- rate the nitrous matter from the alcohol. Then it is that the fuccefs of the operator vaniflies, with a degree of rapidity equal to the advances which encouraged his hopes at the commencement. To purify common fulphuric acid, 100 pounds of it are to be mixed in a large bafon of copper with the fame quantity of river-water, and ftirred with a wooden fpa- tula. The mixture inftantly becomes heated to the boiling water point, and a great quantity of red vapour is difengaged, which has the fmell of aqua-regia, and arifcs from the nitric and muriatic acids. When this mixture is made, it is proper to immerfe the bafon to a fuitable depth in a large veflel of water, to hallen the cooling. As foon as it is fufficiently cooled, it is to be drawn off into bottles, and left to become clear during feveral days. It is in the next place to be decanted, and conveyed into retorts by a fyphon furmel, and the reftification proceeded upon until it becomes perfeftly white. Towards the end of the operation a fmall quan- tity of fulphur fubhmes in the neck of the retort. In- ftead of receivers, a fmall glafs cup is placed beneath the aperture of each retort, in order to facilitate the dil'- fipation of the nitric and muriatic acids. When the acid in the retorts is fufficiently cooled, it is poured a fecond time into the copper bafon, and mixed with loa pounds of river-water, as at firft, and again concentra- ted in the retorts till it becomes perfectly clear. The muriatic acid is to be difengaged from common fait by the application of this acid in the ufual manner. u The oxy-muriatic acid is alfo ufed very generally forBiea.hing bleaching paper, or rather the ftufF out of which paperF^P"- is made. It has been alleged, and we believe with fome truth, that fince this mode of whitening paper was in- troduced into this country, the ftrength of paper is much inferior to what it was formerly. If this be really the cafe, perhaps it is owing to the ufe of too concentrated an acid. We fliall finifti this article with MrChaptal's account of this procefs, who was the firft perfon that introduced ft. " Blotting paper (fays he), by being put into oxy- genated muriatic acid, is bleached without fuftering any injury ; and rags of coarfe bad cloth, fuch ao are ufed in the paper manufaftorles to make this kind of paper, may be bleached by this acid, and will then fur- nifti paper of a very fuperior quality. I bleached by it an hundred weight of pafte, intended to be made into blotting paper, and the increafe of value in the produft was computed at z^^ per cent, whereas the expence of the operation, when calculated in the ftrideft manner, amounted only to "^ per cent. ,. The property poiTelTed by this acid, of bleaching Mosle of . ^ - . . . . g' paper without injuring its texture, renders it very va-*''''''"'''S luable for reftoring old books and fmoked prints. The"''^ '"'"'"' latter, when difcoloured to fuch a degree that the fub- jeift of them could hardly be diftinguilhcd, were re-efta- blifhed and revived, in fo aftonilhing a manner that they appeared to be new ; and old books, foiled by that yel- low tinge which time always produces, may be fo com- pletely renewed, that one might fuppofe them to be The fimple immedion of a print BOA Sleaching print in oxyjjenated muriatic acid (leaving it therein a II lonf^er or a ihorter time, according to the ilrength of • the liquor) is all that is required for bleaching it ; but when a book is to be bleached, fome farther precau- tions are to be ufed. As it is necelTary that the acid fhould wet eveiy one of the leaves, the book mull be completely fpread open, and then, by letting the boards of the binding relt upon the fides ot the vedtl, the pa- per only will be Immerfed in the liquor. If any of the leaves (lick together they mull be carcfnlly feparated, that ail of them may be equally Impregnated. The li- quor takes a yellow tinge, the paper grows white ; and after two or three hours the book may be taken out of the liquor, and foaked in clean water, which (hould be clianged from time to time, in order to wafli out the acid with which the book is Impregnated, and alfo to deprive it of the difagreeable fmell it has con- traded. " The above method, which Is the firft I made ufe of, has generally fucceeded pretty well: too often, how- ever, the leaves of my books have had a motley appear- ance, and fometimes feveral pages were not at all bleach- ed ; I was therefore obliged to have recourfe to the following more certain procefs. 1 began by unfewing the books, and reducing them into (lieets ; thefe Iheets I placed in divifions made in a leaden vefiel, by means of thin (lips of wood, fo that the leaves when laid flat were feparated from each other by very fmall inter- vals. I then put the acid into the veflel, pouring It againft the fide, that the leaves might not be difturbed ; and when the operation was finiihed, I drew off the acid by means of a cock fixed in the bottom of the veflel. I then filled the veffcl with clean water, which ■wafhed the leaves, and took off the fmell of the oxyge- nated acid. They may then be dried, fmoothed, and new bound. In this manner I have reftored many va- luable books, which had become worthlefs from the bad ftate they were in. 13 « When I had to bleach prints fo torn to pieces JAnd prints, ^j^^j. j^^y confifted only of fragments fitted together, and palled upon paper, I \v:is afraid I might lofe fome of thefe fragments in the liquor, becaufe they fcparate from the paper by the foftening of the paile : in that cafe therefore I took the precaution of enclofing the print in a large cylindrical bottle, which I turned upfide- down, fixing Its mouth to that of a veffel in which I had put a mixture proper for difengaging oxygenated muriatic gas. This gas fills the infide of the bottle, and, adting upon the print, takes off the llains, ink-fpots, &c. while the fragments remain palled to the paper, and confequently keep their refpeftive places." BLOCKS (Encycl. Plate XCV. fig. 5.) a Reprc- fents a fingle block, and b, c, two double ones of diffe- rent kinds, without ftraps ; e, /, two double tackle blocks, iron bound, the lower one,/, being fitted with a fwivcl ; g, a double Iron block with a large hook ; h, a fmall block ; /, a top block ; k, a voyal block ; /, a clew garnet block ; m, the cat block, employed to draw the anchor up to the cat-head. See CAT-Heads, Encycl. Cape or Large Snouted BOAR, a fpecies of the genus Sus, which, according to M, Vaillant, differs from every known fpecies, and has not been accurately defcrihed by any writer of natural hidory. Buffon, in- deed, in the Supplement to his Hiftory of Quadrupeds, t 92 1 BON has given a figure of it ; but nothing like the head of Boar, Boiintt. the animal is It was in fome of the above-mentioned differtations that Bofcovich made known firft to the world his fentiments conceroini^ the nature of body, which he afterwards digefted into a re- gular theory, which is juftly become fo famous among the learned. Father Noceti, another Jefuit, had conipofed two excellent poeins on the rainbow and the aurora borealis. Thefe poems were publiflied with learned annotations by Bofcovich ; in which, among other things, he with great fagacity difcovers errors in optics into which Dc Dominis, Kepler, and others, had fallen. His countryman, Benediiit Stay, after having pub- liflied the philofophy of Defcartes in Latin verfe, at- tempted the fame with regard to the more modern and more true philofophy, and has executed it with won- derful fuccefs, to the admiration of all good judges. The two firft volumes of this elegant and accurate work were publifhed with annotations and fupplements by Bofcovich. Thefe fupplements are fo many fliort differtations on the moft important parts of phyfics and mathematics. Here is to be found a foUitlon of the problem of the centre of ofcillation, to which Huygens N had BOS r 98 ] BOS Eofcov'ch. had come by a wrong method > here lie confutes Eu'cr, ' > who had imagined that the vis imrliit was tietefiary in matter ; here he refutes the ingenious efforts of Riccati en the Lcibnitzian opinion of the forces called livirg. He likewife fliews the falfehood of the mathematical prejudice, according to which the right line is confider- cd as efTtntially more furple than curves, and makes it appear that the notion of tlie faid right line is com- monly accompanied with many paradoxes. He demon- ftrates, by the doflrine of combinations, feme beautiful theorems concerning the fpace occupied by the fmall maffes of body, with many ufeful obfervations on fpace and time. Benedict XIV. who was a great encourager of learn- ing, and a beneficent patron of learned men, was not ignorant how valuable a fubjeft Rome poffcffed in Bof- covicli ; and this pope gave him many proofs of the efteem he had for him. Two fiffures which had been perceived in the cupola of the church of St Peter's on the Vatican had occafioned fome alarm. The pope de- fired Bofcovich and fome other mathematicians to make their obfervations, and give their opinion on the fame. They obeyed, and their opinion was printed. They fhewed that there was no caufe to apprehend danger ; but, for greater fecurity, they propofed certain precau- tions, which were adopted and put in execution. The high opinion which the pope had formed of his talents, and the favour in which he was with Cardinal Valenti, minifter of ftate, proved hinderances to his go- ing to America, for which a propofal was made to him by the court of Lifbon. Some differences had long fubfdled between Spain and Portugal concerning the boundaries of their refpeftive dominions in that great continent ; and John V. of Portugal wiilied that Bof- covich would go over and make a topographical furvey of the country in difpute. He was not unwilling to undertake fuch a taflv, which was entirely to his tafte ; and he was refolved at the fame time to meafure a de- gree of the meridian in Brazil, which might be com- pared with that meafured at Quito by the French aca- demicians Bouguer and Condamine, with the Spaniards Ulloa and Doy. But the pope hearing of this propo- fal, fignified to the Portuguefe minifter at Rome, that his mafter muft. needs excufe him for detaining Bofco- vich in Italy, where he had occafion for him, and could by no means confent to part with him. Accordingly a comm^Jlion was given to Bofcovich by Benedift to correft the maps of the papal eftate, and to meafure a degree of the meridian paffuig through the fame. This he performed with great accuracy, alTifted by F. Chriftopher Maire an Englifh Jefuit, and likewife a great mathematician. Their map was en- graved at Rome, and is perhaps the moll; exaft piece of the kind that ever was printed, as all the places are laid down from triangular obfervations made by the ableft hands. Bofcovich alfo publifhed, in a quarto volume in Latin, an account of the whole expedition, which appeared at Rome in the year 1755, and \^3 afterwards printed at Paris in French in the year 17/O. Here he gives a detail of their obfervations and of the methods they followed, and likewife of the difficulties they encountered, and how they were furmounted. One <>{ thefe embarralTed them a good deal at the time, but ■was afterwards matter of diverfion to them and others. Jiome of the inhabitants of the Apennines, feeing them pafs from hill to hill with poles and ftrange machines, Bofcovich, imagined that they were magicians come among their « -' motmtains in fearch of hidden treafUres, of which they had fome traditions : and as tempcfts of thunder and hail happened about the fame time, they fuppofed that thefe calamities were caufed by the forcerics of their new vifitants. They therefore infifted that Bofcovich and Maire fliould depart ; and it was not eafy to convince them that their operations were harmlefs. In this work there is infcrted a defcription of the inftruments made ufe of in determining the extent of the degree of the meridian ; and the whole work may be extremely ufe- ful to praclical geometricians and aftronomers. In the year 1757 the republic of Lucca intrufted Bofcovich with the management of an affair which was to them of confiderable importance. Between that re- public and the regency of Tufcany there had arifen a difagreeable difpute concerning the draining of a lake, and the direftion to be given to fome waters near the boundaries of the two itates. The Lucchefe fenate chofe our pliilofopher to treat of this bufniefs on their part. He repaired to the fpot, confidered it attentive- ly, and drew up a writing, accompanied with a map, to Ihew m.ore clearly what appeared to him moft equi- table and moft advantageous for both parties. In order to enforce his reafons the more efleftually, it was thought proper that he fliould go to Vienna, where the Emperor Francis I. who was likewife grand duke of Tufcany, refided. He was fo fuccefsful in this nego- ciation, that he obtained every thing that Lucca defi- red, and at the fame time acquired great efteem at the Imperial court. In proof of this, tlie Emprefs Queen made his opinion be allied concerning the liability of the Cefarean library, and the repairs to be made in it ; which he gave in writing, and it was received with thanks, as being very well grounded. When he had concluded the affair which had brought him to Vienna, he forefaw that, for a month or two, the fnowsin the Alps would not allow him to return to Italy. He therefore refolved to employ that time in completing his fyftem of natural philofophy, on which he had been meditating for the fpace of thirteen years. He publiftied his work on that great fubjeft in the beginning of the year 1758, in the above-men- tioned city. We ftiall in the end give an account of that celebrated fyftem, and here go on with our narration. On his return to Lucca, he not only met with the approbation of all he had done for the intereft of the republic ; but alfo the fenate, in teftimony of their gra- titude, made him prefents, and enrolled him in the num- ber of their nobiHty, which was the greateft honour they had in their power to confer on him. He, who was thus ufeful to foreigners, could not rc- fufe to be ferviceable to his own country when an oc- cafion of being fo offered itfelf. The Britifh miniftry had been informed, that fliips of war, for the French, had been built and fitted out in the fea-ports of Ragu- fa, and had fignified their difpleafure on that account. This occafioned uneafinefs to the fenate of Ragufa, as their fubjefts arc very fea-faring, and much employed in the carrying-trade ; and therefore it would have been inconvenient for them to have caufed any difguft againlt them in the principal maritime power. Their coun- tryman Bofcovich was defired to go to London, in or- der to fatJsfy that court on the above-mentioned head; and BOS [ 99 ] BOS B./covich. and ultli this dofiie he complied cheeifully on many ac- he taught, with great apphufe, for the fpacc of fix B.ifcovith. ^"-v— counts. His iuccels at London was equal to that at years, having at the fame time the care of the obfcrva- ~~'v " ' Vienna. He pleaded the caufe of his countrymen ef- tory of the Royal College of Brera. Ahout the year jfedually there, and tliat without giving any offence to 1770, the Emprefs Queen made liim piofefl'or of aftro- the French, with whom Ragnfa foon after entered in- nomy and optics in the Palatine fehools of Milan ; re- to a treaty of commerce. quiring of him, however, that he (lioiild continue to Bofcovich came to London the more willingly, as improve the obfervatory of Brera ; which, under liis di- hc was dcHrous of converling with the learned men of rettion, became one of the moft perfeA in Euiope. Britain. He was received by the prelideiit and prin- Here he was extremely happy, teaching the fciences, cipal members of the Royal Society with great rcfped; applying to his favourite ftudies, and converfiug and and to that great body he dedicated his poem on the correfponding with men of learning and of poliflud eclipfes of the iuu and moon, which was printed on rranncrs ; when an event happened which caufed to this occaiion at London, in the year 1760. This is him the moft fenfible affli'^eni of to'the fame. We (hall, finaihu fliew how happily it u^fTl' may be applied to explain the general properties or mat- j ter, as well as the particular qualities of all the clafles of bodies, which have been examined according to what it teaches. j 1. In this fyftem, therefore, the whole mafs of matter. View of of which all the bodies of the univerfe are compofed, J^' fcvich't conlills of an exceedinjj great, vet ilill linite number ^f ')'"<'"i ™ hmple, maivilihle, mcxter.ded, atoms. 1 hele atoms are philof^,pJ,_, endued with repuljive and atlraSive forces, which vary and change from the one to the other, according to the diilance between them, in the following manner : In the leaft and innermoft diftances they repel one ano- ther ; and this repulfive force increafes beyond all li. tnits as the dillances are diminifhed, and is confequent- Iv iufficient for extinguifliing the greateft velocity, and for preventing the contact of the atoms. In the fen- hble dillances, this force is allraSive and decreafes, at leaft fenfibly, as the fqiiares of the diftances increafe, conftituting univerfal gravity, and extending beyond the fphere of the nioft ditlant comets. Between tin's innermoft repulfive force and the outermoil attraftive one, in the infenfible diftances, many varieties and chan- ges of the force, or determination to motion, take place : for the repulfive force decreafes as the diftance increafes. At a certain diftance it comes to vanifti en- tirely ; and, when that diftance is increafed, attraftion philofophy may be to the public ; and of this he gave begins, increafes, becomes lefs, vanilhes; and the diftance another proof when it was referred entirely to his judge- becoming greater, the force becomes repulfive, increafes, ment to determine whether or not the cupola of the ca- lelfens, and vanilhes as before. Many varieties and chan- thedral of Milan could bear the weight of a very high ges of this kind happen in the infenfible diftances, fome- fpire, which it was propofed to raife on it, and which times more rapidly, fometimes more flowly, and fome- was actually eretted accoiding to Ins directions. times one of the forces may come to nothing, and then His application to abftruie ftudies did notjiinder return back to the fame without paffing to the other. For him from paying iome attention to what is more ple.i- fant. We have feen that he was a poet : he was alfo well acquainted with hiftory, and particularly with that of the Greeks and Romans, and with tlieir antiquities. He wrote a diiitrtation on an ancient villa difcovered In his time upon the Tufculan Hill, and on an ancient dial found there; which difi'ertation was publilhed at Rome in a literary journal. He wrote likewife three letters on the obelifk of Casfar Auguftus, two of which were printed with his own name, and the third under the name of another. Befides all thefe works that were given to the public in his lifetime, many writings of his remained in nianu- fcript in the hands of different perfons, and particularly with his friend M. Gaetani, and ninny more with Count Michael de Sorgo, a Ragufau fenator, who inherited all his papers that were in his own hands at his death. Thefe, it is hoped, have either been already fent to the prefs or will be fo ; as nothing came from the pen of Bofcovich which was not ufeful and defcrving 10 fee the light. It now remains that we give an account of his Theory of NATtRAi, Philosophy; and in doing this we (liall, in thejlr/l place, lay before our readers a view of this fyftem. We ftiall, in the yiion;/ place, re- late, from what principles and by what fteps it was de- all this there is full room in the diftances that are in- fenfible to us, feeing the leaft part of fpace is divilible in irjJinUum. Befides thefe repulfive and attraftive for- ces, our atoms have that vis inertia which is admitted by almoft all modern philofopliers. Thefe atoms, en- dued with theie forces, conllitute the whol,' fubftance of Bofcovich's fyftem; which, however fimple and fliort it may appear to be, has numberlefs and very wonder- ful confequences, as we ftiall fee afterwards. But, that The whole a more clear idea of the whole theory may be ealily therry ei- formed, we Ihall make uie of a geometrical figure well l^"""^ ''. accommodated to that purpofe. The right line CAC^^^^^^^_ is an axis, from which, in the point A, is drawn the plate VI. right line AB at right angles. AB is confidered as an fig- 6. afymptole ; on each fide of which the two curves, quite fimilar and equal, DEFGHIKLMNOPQRSTVU on the one iide, and D'E F'G' on the other, are placed. Now, if ED be fuppofed to be afymptohcal, and be ex- tended, it will Hill approach to BA, but will never come to touch it. This curve ED approaches to the axis C'C, comes to it in E, cuts it and departs to a certain diftance in F, after which it again approaches the fame axis and cuts it in G. In like manner it forms the arches GHI, IKL, LMN, NOP, PQL. At lall it goes on in T /> .r V, which is afymptoti- cal, and approaches to the axis ; fo that the diftan- ces from it are in a duplicate reciprocal proportion of the diftances from the right line BA. If from any points of the axis, as from a, b, d, we raife the per. BOS [ 103 ] BOS Ififcovith's perpendiculars a g, b r, d h, tht fegments of the axis fix conditions, let us call tlie ordinate j;, the abfcifs x, Nan^al^^ A (7, A 3, A '*!'* ' 'V/ becaufe before exiftence a being is nothing, and there- *"^*^"''' fore incapable of any ftate. In creation, a being does not pafs from one ftate to another abruptly ; it pafles over no intermediate ftate : it begins to exift and to have a ftate, and exiftence is not divifible. Do we not, at leaft, allow of an abrupt palfage from rcpulfive to attraflive forces in our very theory itfelf? We do not. Our repulfive forces diminifli, through all the interm'=. diate magnitudes, down to nothing ; through which, as a limit, they pafs to attraftion. In tlie building of a houfe or fliip, neither of them is augmented abruptly; becaufe the additions made to them are tdcfted folely by a change of diftances between the parts of which they are compofed : and all the intermediate diftances are gone through. The like may be faid of many other fuch cafes ; and ftill the law of continuity re- mains firm and conftant. Let us now apply this doftrine to the cafe above impolTibi- mentioned of the collifion of two bodies. We fay that'ify of con- the body B cannot pafs from the velocity 6 to the ve- ''"^ ^^' locity 9 without paffing through the velocities 6 and 7 ; j"?^" becaufe if it did, in the moment of contaft of the two fuperficies it would have the velocit|es 6 and 9. Now a body cannot have two velocities at the fatne inftant. For if it had two o&ual velocities at the fame time, it would be in two difl'erent places at the fame time : if it had two different ^(7/.'H//'a/ velocities or deterininations to a certain velocity, it would be capable of being, after a given time, in two places at once — both which are impoffible. It is therefore neceflary that it go through the velocities 7 and 8, and through all the parts of them. What we have faid of the bodies A and B may be faid univerfally of all bodies. Therefore no two bo- dies in motion can come to immediate contact ; but their velocities muft undergo the fucceffive neceflary change before contaft. And as the velocity to be ex- tinguiflied may be increafed beyond all limits, an ade- quate caufe to effedl this extinftion muft be admitted. This naturally leads us to the interior repulfive forces i)„„„^.... ot our lyftem ; tor the caule retarding the one body forces and accelerating the other muft be a force, becaufe by this we mean a determination to motion ; and it muft be repulfive, becaufe it a6ls/ro« the body ; and it muft; O increafc BOS [ io6 ] 15 O S S>riovich's jncreafe beyond all limits, fteing the velocity of the in- for the eflencc of a bang, as mutt lie allowed by all Bi'dovith', iiyfttmof cuiring bodies may be incrcatid beyond all limits. It tliofe who hold that fpii its are iiicxtendcd, Becaufe Syl^fmof Phlof"^ hv '""'^ likcwife be mutual, brcaufe aftiun and readion are all the bodies that fall under our ftnl'es are extended, we pjiiiofoojl nl"'''y equal, as may be proved by induftion. are apt to look upon extenfion as eilential to matter: — ^ \ lo From thefe repulfive forces Bufcovich deduces the but this error may be corrected by reHeftion, and an In exten !- Jnextenfion of his atoms : for this repulfion being com- idea of an iiicxtendcd atom may be formed, by confidcr- e acorns. jj,()ji to all matter, miiil caiil'e a perfeft (implicity in the ing the nature of a mathematical point, which is the firll elements of body. If thefe elements were extend- limit of any two contiguous parts of a line, ed, and confequently compounded of particles of an in- Others again have faid, that if the elements of mat- ferior order, thefe particles might pofiibly be feparated, ter were void t)f extenfion, there would be no diffe- and then they might meet, and an abrupt paffage from rence between body and fpirit. But the difference be- one velocity to another might take place, which we tween body and fpirit does not confift in the having or have excluded from nature by induction, and by a pofi- not having extenfion ; but in this, that the atoms of rive argument. matter are endued with repulfive and attraftive forces, ; Befides this, by rcjecling the extenfion of the firft which fpirit has not; and fpirit has a capacity of thought elements of matter, we get rid at once of all the difli- and volition which bodies have not. culties arifing from continued extenfion in body, which We may here obfervc, that among the ancients Zeno, have always perplexed the philofophers, and have never and among the moderns Leibnitz, held, tiiat the firft been fatisfafforiiy explained. If the elements of matter principles of matter are inextended points. But both are extended, each of them may be divided in Injinllum, held this opinion with the inconfiftency, that they main- and each part may ftill be divided in injiniliim. Can tained the continued extenfion of bodies, without ever this divifion be aftually made by the power of God or being able to ihew how continued extenfion could arife not ? Can there be one injinite in number greater than from inextended elements. another ? Can theie be a compound without 3 Jimple of It has been objefted likewife, that our repulfive and the fame kind ? Thefe difficulties regard not fpace, attraftive forces are no better than the occult qualities which is no real being ; but they wouhl regard matter of the Peripatetics. The like objeftion has been made if it had continued extenfion. All thefe perplexities to Newton's attraftion : but the anfwcr is eafy. We are removed by maintaining, as Bofcovich does, that the obferve the eft'efts, and take notice of them : for them firft elements of bodies are perfeftly fimple, and there- we muft admit an adequate caufe, without being able jj fore inextended (a). to determine, whether that caufe is an immediate law Attraftive With regard to the exterior attraftive forces of our of the Creator, vir fome mediate inflrument that he forces. fvftem, there can be no queftion ; feeing they conftitute makes ufe of for that purpofe. univerfal gravity, the efletts of which we fee and feel Some are unwilling to give up the idea of motion oc- every day. But between the interior repulfive and ex- cafioned by immediate impulfe : but can they {how a terior attractive forces we muft admit many tranfitions good reafon why fome diftance may not occafion motion from repulfion to attraction, and from attraftion back as well as no dijtance ? Thefe are the principal objec- to repulfion, in infenfible dillances, which are indicated tions that have been made againft the Bolcovichian to us by cohefion, fermentation, evaporation, and other fyftem. ij phenomena of nature. And thus we have given, in IV. Before we proceed to the explication of pheno- Obfer»a, iliort, Bofcovich's proofs of his whole fyftem. mena by means of our theory, we muft advert, that in tions with OVaions III. This fyftem has been well received by the learn- the curve exprefling this theory, the abfciffes denote [^1"'^^^ to the fyf. ed in Europe, and has contributed much to render its au- the diftances between the atoms that are under confi- tem an- thor famous ; yet many objeftions againft it have been deration ; the ordinates give the prefent ybrcf, and the Jwered. propofed. Some are ftartled at the rejeftion of all imme- area between any two of thefe ordinates gives the fquare diate contadl between bodies: and indeed Bofcovich is of the velocity generated between them; the arches are perhaps the firft of mankind who advanced that opi- either repulfive or attraftive, according as they fall up- iiion ; but he allows that bodies approach io near to on the fame fide with the afymptotic curve EG, or on one another, as to leave no fenfible diftance between the oppofite fide. them ; and his repulfive forces make the fame imprcflion We muft, in the next place, confider the paffages on the nerves of our fenfcs as the folid bodies could do. from one fide of the axis to the other. Sometimes the And therefore this opinion of his, however new, is no- paffage is from repulfion to attraftion, at other times wife contrary to the teftimony of our fenfes. He only from attraftion to repulfion. The firft are called limits VssvAi fA removes a prejudice which was before univerfal. of cohefion, becaufe a particle removed from that limit cohefion, Some fay, that they cannot even form an idea of an returns back to it ; becaufe if it is removed to a greater^' inextended atom, and that Bofcovich reduces all mat- diftance it is attrafted back, and if it is removed nearer ter to nothing : but certainly extenfioa is not aeceflary it is repelled back. The fecond are called limits of nan- cohefion ; (a) If a particle of matter Is not extended, in what refpeft does it differ from a point of fpace ? Says Bofco- vich, it is endowed with attraftive and repulfive forces. "What is this it before it is thus endowed ? Does it then differ from a point of fpace ? We can form no notion of any fuch difference. But a point of fpace, confidered ae an individual, is diftinguiftied from another individual only by its fituation ; it is therefore immoveable, but matter is moveable. Have thefe forces, then, which make matter an objeft of fenfe, any fubftratum, any thing- in which they are inherent as qualities I What are the things which thefe qualities diftinguifh from each other as individuals i Figure, BOS [ >o7 ] BOS o(covUh'* cctrfon ! becaiifc a particle removed tlience to a great- of coliefion ; for when two atoms are placed in a limit BofcovUl!*! ■.yftcm of er dilbnce is repelled ftill further, and if removed near- of tliat kind, they neceflarily cohere more or lefs ftronir- ^v"'"' "' J!-"""' er it is attradtcd Hill nearer. Of the firft kind are ly, according as that limit is Itronj.cr or weaker. Tiom „,'^"'""',' i.^.r^E. I, N; of the fecond are G, L. Likewife, when the the cohelion uf the atoms arifcs the cohcfion of .-nm. '"'' .•; curve touches the axis, it may either be an attraflive pounded particles, and confcqiuntly of fcnfible bodies, part of the curve, or a repullive part. Thefe limits trom the <:ohelion of panicles arites the extenf.dn of c '\ may be nearer one another, or farther away ; and the bodies; becaufe there mull always be fpace between I lie ' limits of coheiion maybe ilronger or weaker, accord- particles. However, it is evident that this extcnfioti is ing as the forces near them are greater or lefs. not formed of a continuity of matter ; though it may Bofcovich confiders minutely the effeds of thefe va- appear to be fo to our fenfes, which cannot perceive rieties of limits and forces; firft with regard to two tlie fmall intermediate diftance between the riarts of fome points, then with regard to three and four, demonilra- bodies, and much lefs the diihnces between the fimple ting the great variety of forces that may arife from elements of which they are compofed. thefe various combinations, and (hewing how from fun- Extenfion of bodies inxolvesJi^ura/iiUly; becaufe eve- pie atoms a great variety of bodies may be formed. He ry extended body mull be furrounded by fome funerfi- particularly proves, that, from the various polition of cies of a certain figure ; but the fuperticies of bodies the atoms, they may either always repel or always at- can never be accurately determined, upon account of ompofi- traft other atoms, or do neither. Four atoms inay the inequalities in all furfaces. We take, however, that on of bo- form a pyramid, eight may form a cube, and fo on, in figure for the true one which the body appears to come <•• regular or irregular figures. Particles of the lowcll or- ncareft. Thus we call the earth a globe, notwilhfland- der may compofe particles of a fecond order, thefe of a ing the hills and valleys that are on it. third, and fo on. Thfs he exemplifies by a library, in Under the fame figure, and of the fame magnitude, which the letters of the books fiiould be compofed of there may be contained very different quantities of mat- fniall points, placed fo near one another as that their ter. Hence we come to the confidcration of deitfity. dillance could not be perceived without the help of a That body is moft denfe which contains in the fame microfcope. Here the letters will be compofed of fpa'ce the greatett number of atoms, and vice verfa. points, the words of letters, and all the variety of books This denfity may be increafed beyond any given li- rj *f» on different fubjedls, and in different languages, would mits by the nearer approach of tiie atoms to one ano- be compofed of words In like manner, he fays, his ther. Hence a body of any given magnitude, however atoms may compofe particles, thefe may compofe others fmall, may come to be divifible beyond any given li- of different orders, of which may be formed various mits. bodies, animal, vegetable, air, fire, water, earth, whole Mobility, which is likewife reckoned among the ge- Mobilitv neral properties of body, is cfTcntial to our fyilem, fee- ing an effential part of it confifts in forces, which are de- terminations to motion, at leall in certain diftances. Univerfal gravity in fenfible diftances is likewife a Gravity, ,5 planets, central bodies, the whole univerfe. \c fydem But to be more particular, our author proceeds to \\\tA ro apply his fyfteni to mechanics, and demonilrates, with count lor j^jj yfj,jl accuracy and originality, what regards the centre of gravity, atlion and reaftion, the collifion of branch of our theory. On which fubjeft it may be ob bodies, the centre of equilibrium, and of ofcillation. Of ferved, that perhaps our curve, after it has extended thefe fubjefts he treats in the fecond part of his Theoiia; beyond the fphere of the comets moft diftant from the to which we inuft refer our learned readers, as it cannot fun, may depart from its afyniptotical nature, and ap- be eafily abridged. proach to the axis, interfedt it, and pais to repulfion. In the third part of the faine work he proceeds to This would effedlually anfwer the objetlion made by ,y account for the general properties of matter, beginning fome againft Newton's attraction,, when they allege, rtnetra- with impetielraWity. This naturally flows from the in- that, from his opinion, it would follow, that the fixed "y> terior repulfive forces, which prevent the compenetra- ftars, and all matter, would be drawn together into one tion of any two points. Befides, as the leaft part of mafs. If fuch a repulfion takes place, it may foon pafs fpace is divifible in iiifinitum, it is infinitely improbable again into attraftion, and form limits of cohcfion ; fo that any two points fhould ever meet, feeing they have that our fun may be in fuch a limit with regard to the an infinite number of other lines in which they can fixed flars, and our planetary fyftcm make oidy a fmall move, btfides the one that would join them. But an apparent compenetration might take place, if one body fliould meet another with fo great a velocity as not to give time to the repulfive forces to exert their aclion. Thus an iron ball may pafs fwiftly near a flrong mag. pait of the whole uiu'verfe. And this may fuifice con- cerning the general propertits of matter. Let us now defcend to fome particular clafTes of bo- Fluidity dies, of which fome are fluid, others folid. The parts of fluid bodies are eafily feparatcd, and eafily moved iS leHoa, net, without being fenfibly attracted by it, which it round one another, becauie they are fpheiical and very would be if it moved more flowly. Thus a ball from homogeneous ; and hence their forces are direded more a gnn pafles through a piece of wood fo quickly as to to their centres than to one another, and their motions make only a paiTsge for itfelf, without breaking the through one another are lefs obftrufted. Between the neighbouring parts, which it would do were its mo- particles of fome of them tliere is very little attraction, tion more flow. Of this kind of compenetration we as in fine fand or fmall grains of feed, which approach have a refemblance in light pafling through pellucid bo- much to fluidity. The particles of fome others of them dies. attraft one another fenfibly, as do tliofc of water, and Cohefion has never been well accounted for by any ftill more thofe of mercury. This variety ariles from phdofopher before Bofcovich. From his fyftem it fol- the various combinations of the particles thend'elves, of Jows naturally, as we have feen in fpeaking of the limits which ve have already taken notice. But in air the O 2 particles BOS [ 10 Bofco»ich's particles repel one another very ftrongly ; and hence ''n*'" "\ '-'""■'^^ *''*' great rarefaftion, when it is not comprefi'ed Philofophy ^5 Solidity, 17 Vircofity. 28 Organiza- tioa. by an external force. Its particles muft be placed in ample limits of repulfion. Solid bodies are formed of parallclopipeds, fibres, and of irregular figures. This occafions a greater cohefion than in fluids, and prevents the motion of the parts round one another ; fo that when one part is moved all the reft follow. Of thefe bodies fome are harder, whofe particles are placed in limits which have ftrong repiil- - five arches within them ; others are iofter, whole parti- Softnef' cles have thofe arches of repullion weaker. Some are flexibility, flexible, the particles of which are placed in limitsthat and elalli- have weak arches of repulfion and attraction on each "^"y* fide ; and if thofe arches are (liort, the particles may come to new limits of cohefion, and remain bent : but if the arches are longer, the former repulfion and attrac- tion will continue to a£t, and bring back the body to its former pofition ; nay, in doing this with an accele- rated velocity, the parts will pafs their former limits, and vibrate backwards and forwards, as may be feen in a bended fpring. Tl'.us elafticity is accounted for. Vifcous bodies Hand in the middle between folid and fluid. Their particles have lefs cohefion than the firft, and more than the fecond : they Hick to other bodies by an attrattion which their particles have from their compofition. In like manner water itfelf flicks to fome bodies, and is repelled by others. All which arifes from the different compofition of the particles, which gives a variety of refpettive forces. What appears very wonderful in nature, is the com- pofition of organic bodies. But if we confider that particles may be fo formed, that they may repel fome and attrafl others, the whole of vegetation, nutrition, and fecretlon, may be underftood, and follows from our fyftem. And as one particle may attract another in one part only, and repel it in every other fituation, hence may be gathered the orderly fituation of the par- ticles in many cryftallizations. The great variety of re- pulfive and attractive forces, or linjits of cohefion, of the pofition of atoms, and of combinations of particles, will account for all thefe phenomena. The chemical operations, which are fo curious In themfelves, and fo ufeful to fociety, are well explained by Bofcovlch's fyftem, and ferve as a confirmation of its truth. Of this we fliall give fome inft^nces. When fome folids arc thrown into fome liquids, there hap- pens to be a greater attraction between the particles of the folid and of the liquid than there is between the particles of the folid itfelf. Hence the particles of the folid are detached and furrounded by the fluid ; this mixture retaining the form of globules, and therefore continuing to be fluid. This is called folutloii. But when the folid particles are covered to a certain depth, the attraftive forces ceafe on account of the different diftances, and no more of the folid is detached. Then the fluid is faid to be faturated. If into this mixture another folid be put, the particles of which attraft the fluid more ftrongly, and perhaps at greater diftances than the particles of the former ; then the fluid will abandon the former and cleave to the latter, dlflolving them, and the particles of the former will fall to the bottom in the form of powder, into which they had been reduced by the folution. This feparation is called frecifuation. Perhaps rain arifes from a precipitation «9 Chemical operations. 8 ] BOS of this kind, when the aqueous particles are left by the Bnfcovich'i air, which is more ftrongly attraded by fome other par- Siftcm of tides floating in the atmofphere. pn"r'"h Fluids of the fame fpccific gravity are eafily mixed ; ' ' and even though llie fjieclfic gravity be dift'erent, the particles of the one attract thofe of the other, in fucha manner that they feera to form one fluid by a kind of folution. Nay, it happens that two fluids mixed toge- ther form a folid, becaufe their particles come to be in the limits of cohefion. They may even occupy lefs fpace than they did before, by being attracted into lefs diftances between their parts. Fermentation is a necclfary confequence of our fyf- tem. For when bodies, whofe particles, by the variety of their compofition, are endued with different forces, come to be mixed, there muft arlfe an agitation of the parts, and an ofcillation among them ; fometimes great- er, fometimes lefs, according to the nature of the par- ticles. This agitation is ilopped by the expulfion of fome particles, by the intrufion of others into vacant fpaces, and by the impreflion of external bodies ; but always there is a change in what remains, becaufe there ( is a new difpofition of particles. ,- Fire confifts in a violent fermentation of fulphure- Fire and fu ous matter, efpecially when it meets with the matteriion, &c. of light in any quantity. This fermentation agitates ftrongly the parts of other bodies, feparates them from one another, and often throws them into a ftate of fu- fion ; the cohellon between their parts being broken, and they being thrown into a circular motion. In this ftate they may be often mixed together, fo as to form one body ; they may be again feparated by the aftion of the fame fire, which evaporates fome of them fooner, fome later. Hence the art of fmelting metals. When, in the agitation occafioned by fire, fome of the particles are thrown out into an arch of repulfion, they may fly off^ and evaporate. Sometimes the whole body may be thrown into a ftrong repulfion and volati- lizatlon, or a fudden explotion take place ; when, be- fore the particles are near an equilibrium, a fmall force may occafion a great change ; as the foot of a bird may occafion the fall of a great rock, which was before al- moft detached from a mountain. In evaporation, the bodies that remain affume a particular figure, as all falts do ; and this upon account of their particles ha- ving certain parts only that attraft one another, and confequently occafion a particular difpofition. All thefe chemical operations evidently prove that there are in nature repulfive and attraftive forces between the par- ticles of bodies at fmall diftances : which greatly con- firms our whole fyftem. Bofcovich holds, that light is an efflwvium, emitted Lighu with great velocity from the luminous bodies by a ftrong repulfion. He explains all the moft remarkable properties of this extroardinary matter according to his own principles, and that with great acutenefs. On this fubjeft it is obfervable, that Newton faw the neceflity of admitting repulfive forces for the reflexion of light, which extend at fome diftance from the reflefting fur- face, and therefore referable the repidfive forces of our theory. ... . . 3» Our author gives likewife a probable explication ofgig^^rjcj eleftricity, according to Franklin's ingenious hypothe-aud mag! fis, and likewife of magnetifm, deducing the whole ofnetiihi. the appearances from various attradioDs and repulfions. He 1 iyftcm of Naturr.l hiliifophy. 3.1 BOS . [ 109 ] BOS He fiippofes that fire and the elcdlrical fluid differ only Wherefore 1 do not hcfitate to maintain the above faid EorfovJch's in this, that fire is in actual fermentation, and not fo principles of motion, feeing they extend widely through ''y'*"-"^ ot all nature." From this paifagc we may fafely conclude, phiio'ibphy, that the great Briti(h philufopher would have been ' highly plcaftd, had he fecn all nature fo well explained by the one liuiple law of forces propoftd by the Ragu- the cleftrical fluid Finally, he explains our bodily fenfations, in which he agrees pretty much with other pliilofophers ; except- ing in (his, that what they attribute to the immetliate contact of bodies, or of certain particles emitted from them, he afcribes to attractions and rcpullions ; which indeed are particularly fit for caufing that motion in cur nerves, which is fuppofed to take place in the or- fan . a 6 34 ecoucilia- on of this ith other 'Items, Bofcovich himfelf was fo fully convinced of the truth Comi ari. of his fyllem, that he was wont to make ule of tlic fol- '"" "f 'hij lowing coniparifon : When a letter has been written in'?'^'^'" '°. gans of fenfation, and to be thence communicated to occult charaders, and we arc endeavouring to decyphcra cyihtr, the brain, it, we make various fuppofitions of alphabets ; and It is to be obferved, that although Bofcovich main- when we have found one according to which the v\hule tains that the very firll elements of matter are void of letter comes to have a reafonable meaning, agreeable to extcnfion ; yet he allows, that of thefe elements, com- all the circumllances of time, place, perfons, and things, we can entertain no doubt of our having difcovered the true key of the cypher — fo, faid he, my fyftem explains fo well all the phenomena to which it has been properly applied, that I muft flatter myfelf that I have difcover- ed the true kev of nature. 3^ rpecially lat of /»/? eternity, though it can continue witiiout end. God alone can be eternal and aclually infinite ; but his eternity and infinity are beyond our comprehenfion. Neither can the world have exilled of itfclf in any thing like to its prefent form from all eternity ; for malter is perfcdiy iiidifterent to numbcrlcfs ilates, and to its prefent (late it muft be determined. This prefent ftate is perfeftly incapable of determining itfclf, bccaufe tliis determination mull be previous to its exilience. It niuil be determined by the preceding ftate, which is al- fo incapable of determining ilfelf, and for its determina- tion we mull have recourfc to the ftate before. Thus, though we go back to eternity, we fhall ftill find a nul- lity of determination ; now an infinite fum of nothing is nothing: and iheretore as the prelcnt ftate of things could have no determination, it could not pofiibly exift. It is therefore evident that there muil be a Determi- ner extrinfic to the material word. This Determiner muft have an infinite knowledge of all the poflible com- binations, and an infinite eleftive creative power to chufe and create freely the combination he pleafed, in that point of eternity that he chofe, with all the numberlefs eircumftances that are agreeable to him. And here what a vaft held of contemplation is laid open to a philofophic mind ! Wliat a truly infinite knowledge was requifite to forefce fo many ends, and fo many means requitite for obtaining thofe ends, as are contained in the creation! Let us confider light, for ex- ample, which was to be emitted for fo many ages from fo many luminous bodies, with fo great velocity, fo as ,to penetrate fo many mediums with diff^erent degrees of refledllbllity and refrangibility, with fo many other won- derful qualities ; at the fame time, fo many bodies were to be perfectly fitted for reflefting this light in a cer- tain manner, and the animal eye was to be fo formed as to have a picture of vifible objecls painted on the bot- tom of it. - How many particular combinations were neceftary for all this ? What ftiall we fay of the fo ma- ny herbs, flowers, trees, and animal bodies, as there are on this our earth ? AH their kinds and fpecies, all the feries of their individuals, all their parts and particles, were forefeen, intended, and contrived, by one ac^ of the Divine Mind. Again, how wonderful are the hea- venly bodies, of what furprifing magnitude, moving in the moft beautiful order, at an immenfe diftance from one another ? To fay nothing of the numberlefs crea- tures that are beyond the reach of the beft telefcope, or below that of the microfcope. He who reflects ever fo little on thefe things, muft necelfarily fee the moft evi dent proofs of an infinite power, wifdom, and provi- dence ; and he muft be filled with admiration and awful refpeft for the Creator and Ruler of the univerfe. Nor are we unconcerned fpcftators of this grand fcene. God has been pleafed to make us enter deeply into his great plan of creation. He fingled us out among an infinite number of poflible human beings, in order to call us into exittence at a fixed period ; and he has made a vaft number of his creatiires contribute to the formation of thefe wonderful machines, our bodies, as likewife to our nouriftiment, to our prefervation, to our neceflilies, conveniences, and gratifications. Every o ] BOS moment that we exift, we are enjoying a great number BodiTcn. of benefits, exprefsly difigned fur us by that Supreme ~~-v— ' Being. This evidently demands from us the higheft degree of gratitude, love, and obedience. Let us go a ftep ftill farther : Is it not very reafon- Revelation, able to fuppole, that our God, who affords us fo many inftances of his beneficence towards us in the natural order, will alfo, out of compaflion to our weaknefs and ignorance, have favoured us with a more full and expli- cit manifeftation of himielf, of our duties towards him, and of his intentions concerning us? According to Bof- ' covich and all true philofophers, reafon itielt alone, and true philofophy, point out to us the probability at leaft of God's having given us a tlill better and furer guide, by whofe direftion we may attain to that perfect happi- nefs which we naturally thirft after, and to which we muft have been defigned by our Maker. This is pro- bable from reafon alone ; and of this great fa6t we are afcertained by unqueftionable authority. BOSHMEN have been generally defcribed as a di- flinct race of Hottentots, who are enemies to the pafto- ral life (fee BosHiEs-Men, Encycl. ) This M. Vaillant affirms to be a miftake ; and we think he has complete- ly proved that it is fo. " Thefe infamous wretches (lays he) do not form a particular nation, nor are they a people who have had their origin in tlie places where they are now found. Bojhmen is a name compofed of" two Dutch words, which fignify bujh-vien, or men of the •woods ; and it is under this appellation that the inhabi- tants of the Cape, and all the Dutch in general, whe- ther in Africa or America, diftinguifli thofe malefactors or affaffins who defert from the colonies, in order to efcape punifliment. In a word, they are what in the Britifli and French Weft India iflands are called Maroon Negroes. Thefe Bofhmen, therefore, far from being a diftinft fpecies, are only a promifcuous affemblage of mulattoes, negroes, and maftizos, of every fpecies, and fometimes of Hottentots and baiters (fee Baster, Sup- plement), i\ho all differing in colour, refemble each other in nothing but in villany. They are land pirates, who live without laws and without difcipline, abandoned to the utmoft mifery and defpair ; bafe deferters, who have no other refources but plundering and crimes. They retire to the fteepeft rocks and the moft inacceflible ca- verns, and there they pais their lives. From thefe ele- vated places they command an extenfive profpedt over the furrounding plains, lie in wait for the unwary tra- veller and the fcattered flocks, pour down upon them with the velocity of an arrow, and iuddenly tailing up- on the inhabitants and their cattle, flaughtei them with- out diftinftion. Loaded with booty, and whatever they can carry with them, they then repair to their gloomy caves, which they never quit till, like the lions, hunger again impels them to frefh maffacres. But as treachery always marches with a trembling ftep, and as the pre» fence of one refolute perfon is fufficient to overawe whole troops of thefe banditti, they carefully fliun thofe plan- tations where they are certain that the owners their.- felves refide. Artifice and cunning, the ufual refources of timid fouls, are the only means which they employ, and the only guides that accompany them in their ex- peditions." — F^aillant's Travels into the Interior Parts of Africa (a). BOSWELL (a) Since this article was firft publiflied, a diff"erent account has been given of the Bojhmen or Bojesmans by Mr BOS [ 1 BOSWELL (James), known to the learned world ' as the author of a life of l)r Johnfori and of feveral other valualile works, was born, we believe, at Auchinlcck in Airlhire, in 1740. The family from which he fprung was ancient and honourable. At the time of his birth his father was a well employed lawyer at the Scotch bar ; but was afterwards raifed to the dignity of Judge, and filled that important llation with acknowledged learning, probity, and honour. His title was Lord Auchinleck, taken from his family inheritance ; and he died in 1782 : on which occafion Dr Johnfon wrote an elegant and inftruAive letter to the fubjeft of this brief memorial; of which we (hall tranlcribe a paflage that alludes to fome flight domellic ditferences, which did not happen in vain, fince they gave rife to fuch falutary advice : " Your father's death had every circumftance that could enable you to bear it. It was at a mature age, and it was expefted ; and as his general life had been pious, his thoughts had, doubtlefs, for many years palt, been turned upon eternity. That you did not find him fenlible mull doubtlefs grieve you ; his dilpofition to- wards you was undoubtedly that of a kind, though not of a fond father. Ivindnefs, at kait aftual, is in our own power, but fondnefs is not ; and it, by negligence or imprudence, you had extinguilhed his tondncfs, he could not at will rekindle it. Nothing then remained betvireen you but mutual forgivenefs of each other's faults, and mutual defire of each other's happinefs." The occafion of this family diffention is unknown to us. It might originate in the ditlerence of their poli- tical principles, Mr Bofwell being a zealous Tory, and his father, as he reprefents him, a rancorous Whig ; or it may have arifen from the celebrated Douglas caufe, which fct many friends at variance in Scotland, and in which, though Lord Auchinleck and his fon took the fame fide, they took it with very different degrees of ardour. The Judge faw not the propriety of illumina- ting his windows when the caufe was finally decided by the Houfe of Peers ; and to compel him to illumi- nate, the advocate got polfeflion of a Chincfe gong, and at the head of a number of young men and boys pa- trolled the ftreets of Edinburgh, and made a loud and exulting noife at the windows of his father's houfe, where there was no fymptom difplayed of the general joy- In 1762 Mr Bofwell made his firfl journey to Lon- «3on; where, under the aufpices of Dudlley the bookfel- ler, he publifhed, " The Cub at Newmarket, a Tale." By the title of Cub he meant to charafterife bimlelf, as the reader will perceive in the following lines, which we fliall give as a fpecimen of the poem : ■ Lord Eglintoune, who loves, you know, A little dafh of whim, or fo. By chance a curious Cub had got, Qu Scotia's mountains ne-.vlv caught. During his ftay in London Mr Bofwell was intro- duced to Dr Johnfon, with whom it is well known he II ] BOS continued to live in intimacy from that time till John- Bofwell. fon'a death in 1784 ; and this intimacy procurer liim ''""" the friendfhip of Burke, Goldfmith, Sir Jodiua Rey- nolds, and many other men of eminence, who compofed what was called The Literary Club. In the latter end of 1765 he became acquainted with General Paoli when on his travels ; and after his return he publifhed, in 1768 or 1769, his account of Corfica, with the " Jour- nal of a Tour to that llland." Of this work, which gained him fome diflinftion in the world, his great friend Johnfon writes thus: " Your hiftory is like all other hillories, but your journal is in a very high degree curious and delightful. There is be- tween the hiflory and the journal that difference which there will always be found between notions borrowed from without and notions generated within. Your hif- tory was copied from books ; your journal rofe out of your own experience and obfervation. You exprefs images which operated llrongly upon yourfclf, and you have impreffed them with great force upon your read- ers. I know not whether I could name any narrative by which curioiity is better excited or better grati" fied." In 1770 Mr Bofwell, who was then in good prac- tice at the Scotch bar, married an amiable woman, by whom he had two fons and three daughters, who fur- vived him. In 1773 he was chofen a member of the Literary Club ; and in the autumn of the fame year he vifited the Hebrides in company with his illuftrious friend Johnfon ; after whofe death he publifhed a very entertaining account of their tour, the places they faw, the charadters with whom they converfed, and their own remarks on the different' converfations. To many per- Ions, both in England and Scotland, this book gave great offence, as it brought before the public the un- guarded talk of private locial circles ; but it furely fur- nifhed much entertainment, as it exhi'oited a more faith- fui pifture of Hebridiaii manners than the Britifh pub- lic had ever before feen. In [784, when Mr Fox's famous India bill was be- fore Parliament, Mr Bofwell publiflied a '' Letter to the • People of Scotland on the Pret'ent State of the Na- tion ;" in which he contends, that no charter would be fafe if that bill fhould pals into a law ; and more than inflnuates, that the principle of it was equally inimieai to the liberties of the fubjeCt and to the prerogative of the king. Dr Johnfon ftcros to have thought of that bill as he did ; tor having read the letter, he wTites to the author his approbation of it in the following words: " I am very much of your opinion ; and, like you, feel great indignation at the indecency with which the king , is every day treated. Your paper contains very confi- • derable knowledge of the hiflory and of the conilitu- - tion, very properly produced and applied."" In 1785, Mr Bofwell quitted the Scotch bar, and • went to refide in London, where he continued till the day of his death. Having entered himfelf in one of the inns of court, and fludied the Enghlh law, he became a barjjfler in England ; but we have reafou to believe that Mr Barrow, who travelled into the interior of Southern Africa in 1 797 and 1 798. According to him, they are a dillinft race, e.ttremely favage, who neither cultivate the ground, nor breed cattle, but fubfift in part un the natural produce of their country, and fupply its deficiency by depredations on the colonills oa one fide, and tke : Deighbouring tribes of people that are more civilized than themfelv^s, on the other . BOS [ II Bnfwcll. tViat his praftice there was not fo fuccefsful as it had ^ ' V been in his own country. He enjoyed, however, more completely than he could do in Edinburgh, the conver- fation of the great, the wile, the witty, and the good ; am! fnch converfation he always valued above wealth. He frequently vifittd his native country, and elpecially Auchinleck, the feat of his anceftors ; and foon after his return from one of ttiofe vifits he was feized with a diforder which proved fatal, on TuefJay the iptli of May 1795. Such were the principal events in the life of Mr Bof- well. Of his charafter, it would be difficult to fay ■much more than he has faid himfelf in his " Journal of a Tour to the Hebrides j" and which may, with feme propriety, be copied here: " I have given a flcetch of Dr Johnfon. My readers ■may wifli to know a little of his fellow-traveller. Think, then, of a gentleman of ancient blood ; the pride of which was his predominant paffion. He was then in his 33d year, and had been about four years happily married. His inclination was to be a foldier ; but his father, a refpeftable Judge, had prefTed him into the profeffion of the law. He had travelled a good deal, and feen many varieties of human life. He had thought more than any body fuppofed, and had a pretty good ■ftock of general learning and knowledge. He had all Dr Johnfon's principles, with fome degree of relaxation. He had rather too little than too much prudence ; and his imagination being lively, he often faid things of which the effedl was very different from the intention. He refembled fometimes * The bed good man, with the worft-natur'd mufe.' •' He cannot deny himfelf the vanity of finifhing with the encomium of Dr Johnfon, whole friendly partiality to the companion of this tour, reprefents hiin as one « whofe acutenefs would help my inquiry, and whofe gaiety of converfation, and civility of manners, are fuf- ficient to counteraft the inconveniences of travel, in countries lefs hofpltable than we have pafTed.' Few of Mr Bofwell's friends, we believe, could add much to this candid confefiion. His enemies, if he had any, might dwell upon his failings; but his failings were few, and Injurious to no perfon. In his charafter good nature was predominant. He appeared to entertain fen- tlments of benevolence to all mankind, and to be inca- pable of intentionally injuring a human being. His con- verfation -talents were always pleafing, and often fafci- nating. But can we wonder at this in him who, with a capacity to learn, had been the companion of Johnfon for more than 20 years ? His attachment to the Doc- tor for fo long a period, was a meritorious perfeverance in the defire of knowledge. To it the world is in- debted for the moll: iinifhed pifture of an eminent man that ever was executed. We know there are objedlions to the mode of giving the life of Johnfon. It has been thought that Ignorance has been wantonly expofed, and the privacy of foclal life endangered. We (hall not en- ter deeply into this queftion. All that we can certain- ly affirm is, that the work has been read with avidity and pleafure ; and that he who does not wirti to read it again may be fufpefted to be deficient in tafte and in temper. Mr Bofwell has been accufed of vanity ; but when this accufation is brought againft him, it fhould not be 2 ] B O U forgotten that he enjoyed advantages which rendered Botany. that confpicuous in him from which no man can claim ''^V' an exemption. We know not the man who would not ^"^"'^''' have been vain to poflefs fo much of Dr Johnfon's con- " vcrfation, and proud to give it to the world, in hopes that he wlio venerated Johnfon would not be unthank- ful to his biographer. From the Dodtor, however, he appeared to his friends to have imbibed a portion of me- lancholy, of which indeed he complained himfelf during the lall two or three years of his life ; and he flew for relief where perhaps it is beft to be found, to the fociety of the learned and the gay. Here, as he confefles, he «' had rather too little than too much prudence ;" and, with more attachment to the aflivity of rural life, he might, probably, have lengthened his days. But as his " belief in revelation was unfliaken," and his religious impreffions deep, and recurring frequently, let us hope that he has now attained that ftate from which imper. feftlon and calamity are alike excluded. BOTANY-BAY. See Neif Holland, Encycl. ; and Neiv South IValrs in this Supplement. BOUGUER (Peter), an eminent mathematician and mechanical philofopher, was born at Croific, in Lower Bretagne, on the loth of February 1698. His father John Bouguer, who was likewlfe a coniiderable mathe- maticlan, was then profeffor royal of hydrography at that port ; and under him young Bouguer ftudied ma- thematics, and the application of them to fhip-buildlng, almoft from the period when he began to fpeak ; fo that he was a proficient in thefe fciences before he had reached beyond the years of childhood. He was, how- ever, removed from Croific to the Jefuits college at Vannes, where, at 13 years of age, he triumphed, in a public conteft, over a profeffor of mathematics, who had advanced a mathematical propofition erroneoufly. Two years after this he loft his father, whom he was appoint- ed to fucceed in the office of hydrographer, after being publicly examined, and giving the moll complete proof of his being duly qualified to fill the vacant chair. He was indeed qualified by prudence as well as by fcience ; for however furprlfing it may be, he filled it both with dignity and with abilities, though then not more than 15 years of age. In the years 1727, 1729, and 173 1, he gained the prizes fucceffively propofed by the Academy of Sciences for effays on the bell way of equipping Ihlps with mails, on the beft method of obferving at fea the height of the ftars, and on the moft advantageous way of obferving the declination of the magnetic needle or the variation of the compafs. In 1729 he publilhed an Optical EJfay upon the Gradation of Light, in which he examined the intenfity of light, and determined Its degrees of diminu- tion in paffing through different pellucid mediums, and particularly in traverfing the earth's atmofphere. Of this effay, which was written upon a fubjeft that till then had not attracted the attention of phllofophcrs, the read- er will find fome account in the Encyclopedia Britan- nica, under the title Optics, n" 32, cScc. In 1730 Bouguer was removed from the port of Croific to that of Havre. In 1731 he obtained, in the Academy of Sciences, the place of affociate geometri- cian, vacant by the promotion of Maupertuis to that of penfioner ; and in 1735 he was promoted to the office of penfioner-aftronomer. The fame year he was fent on the commiffion to South America, along with Meffrs Godin, B O U [ II Siingutr. Godi'n, Condamine, and JeulTieu, to determine the mea- ^' » ' lure of the degrees of the meridian, and the figure of the earth. In this painful and troublefome bufuuis of ten years duration, chiefly among the lofty Cordeh'cr mountains, our author, hefides attending to the objedl of the voyage, made many fcientific obfervations ; viz. on the effedl of the Cordeh'ers on the polarity of the mag- netic needle; on the expanfion and contradlion of metals and other fubllances, by the fudden and alternate chan- ges of heat and cold among thofe mountains ; and on the refraction of the atmofpherc from the tops of the fame, with the fiiigular phenomenon of the fudden in- creafe of the refraction, when the Har can be obferved below the line of the level. He likewife afcertained the laws of the denfity of the air at different heights, from obfervations made at different points of thofe enormous mountains j he difcovered that the mountains have an effeft upon a plummet, though he did not affign the quantity of that effect ; he found out a method of etli- mating the errors committed by navigators in determi- ning their route ; gave a new conftruftion of the log for meafuring a Ihip's way ; and made feveral other ufe- ful improvements. M. Bouguer made at different times fome important experiments on the famous reciproca- tion of the pendulum ; he invented in i 747 the Helio- METER (fee that article Encycl.) ; and made many dlf- coveries relating to the intenfity of light (for which fee ' 0?r\cs-/ni/ex, Encycl.) His unremitting application to ftudy undermined his health, and he died on the 15th of Auguft 1758, in the 6ift year of his age. Of his works which have been publifhed, the chief are, i. The Figure of the Earth, determined by the Obfervations made in South America, 1749, '" 4'°- 2. Treatife on Navigation and Pilotage, Paris, 1752, in 4to. This work has been abridged by M. La Caille, in one volume 8vo, 1768. 3. Treatife ou Ships, their Conftruftion and Motions, in 410, 1756. 4. Optical Treatife on the Gradation of Light, firfl in 1729, then a new edition in 1760, in 410. His papers that were inferted in the Memoirs of the Academy are very numerous and important : as, in the Memoirs for 1726, comparifon of the force of the fo- lar and lunar light with that of candles ; 1731, obfer- vations on the curvilinear motion of bodies in mediums ; 1732, upon the new curves called the lines of purfuit ; 1733, to determine the fpecies of conoid, to be con- ftrufted upon a given bafe which is expofed to the fhock of a fluid, fo that the impulfe may be the leaft poflible ; determination of the orbit of comets; 1734, compari- fon of the two laws which the earth and the other pla- nets mull obferve in the figure which gravity caufes tliem to take ; ou the curve lines proper to form the arches in domes ; 1735, obfervations on the equinoxes ; on the length of the pendulum ; 1736, on the length of the pendulum in the torrid zone ; on the manner of determining the figure of the earth by the meafure of the degrees of latitude and longitude; 1739, on the allronomical refractions in the torrid zone ; obfervations on the lunar eclipfe of the 8th September 1737, made at Quito; 1744, fliort account of the voyage to Peru by the members of the Royal Academy of Sciences, to meafure the degrees of the meridian near the equator,and from thence to determine the figure of the earth ; 174;, experiments made at Quito and divers other places in the torrid zone, on the expanfion and contraftion of metals SuppL. Vol, L Part L 3 ] B R E by heat and cold ; on the problem of the mailing of Dou^uer, fhips; I 746, treatifeonfhips, their flru(?furt and motions; . on the impulfe of fluids upon the fore parts of pyrami- doids, having their bafe a trapezium ; continuation of the fhort account given in 1744 of the Toyage to Peru for meafuring the earth ; 1747, on a new co;iRruftii>n of the log, and other inflrumcnts for meafuring the run of a fhip; i 748, of the diameters of the larger planets j the new inftrument called a helionicler, proper for deter- mining them, with obfervations of the fun ; obfervatioi\ of the eclipfe of the moon the Hth of Angull 1748 ; 1749, fecond memoir on aflrononiical refractions, ob- feved in the torrid zone, with remarks on the manner of conftrudting the tables of them ; figure of the earth determined by MM. Bouguer and Condamine, with an abridgment of the expedition to Peru; fj^o, obferva- tion of the lunar eclipfe of the 13th December 1750 j 1 75 1, on the form of bodies mofl proper to turn about themfelves, when they are pufhed by one of their ex- tremities, or any other point ; on the moon's patallax, with the eftimation of the changes caufsd in the paral- laxes by the figure of the earth ; obfer\a'.ion of the lu- nar eclipfe the 2d of December 1751 ; 1752, on the operations made by feamen, called correRlons ; 1753, obfervation of the palTage of Mercury over the fun the 6th of May 1753 ; on the dilatations of the air in the atmolphere ; new treatife of navigation, conlaiiiing the theory and praftlce of pilotage, or working of flu'ps ; 1754, operations, :kc. for diilinguilfiing, among the different determinations of the degree oi the meridian near Paris, that which ought to be preferred ; on the direftion which the firing of a plummet takes; folution of the chief problems in the working of fliips ; 1755, on the apparent magnitude of objeCts ; fecond memoir on the chief problems in the working of fhips ; 17571 account of the treatife on the working of fhips ; on the means of meafuring the light. BREAD is fo effential an article of food that every ufeful method of making it fhould be generally known. Much has accordingly been faid on that fubjeft [Encycl. ) under the titles Baking, Barm, Bread, and Yeast : but, fince the laft of thcfe articles was publiflied, we have feen, in Dr Townfon's Travels in Hungary, a me- thod of making bread at Debrctzen ; of which, as it may fometimes be adopted with advantage in this coun- try, an account may, with propriety, be inferted here. '♦ In the baking of this bread, a fubftitute is ufed for yeafl, which is thus made : Two good handfuls of hops are boiled in four quarts of water : this is poured upon as much wheaten bran as can be well moiRened by it : to this are added four or five pounds of leaven ; when this is only warm, the raafs is well worked to- gether to mix the different parts. This mafs is then put in a warm place for 24 hours ; and after that, it is divided into fmall pieces about the fize of a hen's egg, or a fmall orange, which are dried by being placed upon a board, and expofed to a dry air, but not to the fun ; when dry, they are laid by for ufe, and may be kept half a year. This is the ferment ; and it may be ufed in the following manner : For a baking of fix large loaves, fix good handfuls of thefe balls, broken into fiag- ments, are taken and diffolved in feven or eight quarts of warm water. This is poured through a fieve into one end of the bread trough', and three quarts more of warm water are poured through the fieve after it, and what P remains B R E [ n Bread. remains in tlie fieve is well pretTcd out. This liquor is mixed up with fo much flour as to form a mafs of the fize of a large loaf: this is lire wed over with flour; the fieve, with its contents, is put upon it, and then the whole is covered up warm, and left till it has rifen enough, and its furface Iihs bejjiin to crack : this forms the leaven. Then i 5 ipiarts of worm water, in which fix handfuls of fait have been diflolved, are poured through the fieve upon it, and the neceflfary quantity of flour is added, and mixed and kneaded with the lea- ven : this is covered up warm, and left for about an hour. It is then formed into loaves, which arc kept in a warm room halt au hour ; and after that, they are put in the oven, where they remain two or three hours, according to the fize. The great advantage of this ferment is, that it may be made in great quantities at a time, and kept for ufe. Might it not on this ac- count be ufcful on board of fliips, and likewife for ar- mies when in the field ? Bread, in whatever way it is made, is a dear article ; and it may be a defirable objeft to many of our readers to know at what price the baker can afford to fell it. This depends upon the price of wheat, the quantity of flour which the wheat may give, the lofs at the mill, the expence of grinding, and the expence of baking. Of the price of wheat we can fay nothing with pre- cifion, becaufe it varies according to the goodiiefs or badnels of the crop, and other circumftances ; but a bufhel of Effex wheat, Winchefter meafure, may be taken, on an average, as weighing 60 lb. Sixty pounds of wheat will yield, exclufive of the lofs in grinding and drefllng, 45i lb. of that kind of flour which is cal- led fecnn^/s ; wlilch alone is ufed, through the greateft; part of England, for bread, and which makes, Indeed, the bell of all bread, though not the whitefl. A peck of this flour, weighing 141b. will take up between fix and feveri pints of water, and give 18 lb. of excellent bread ; or a bufliel of flour, weighing 56 lb. will yield 72 lb. of bread. The expence of baking a bulhel of fuch flour is, in Effex and fome other Englilh counties, about nintpence ; viz. yeaft, on an average, twopence ; fait, before the late tax, one halfpenny ; and baking, fix pence. But f^coiids is not all that is got from wheat. A bufliel of 60 lb. of wheat gives, befides 454^ lb. of fe- conds, 13 lb. of offal, i.e. of pollards and bran; for the utmofl lofs in grinding and dreffing a bufhel of wheat fliould not exceed i pound 8 ounces. The millers, in- deed, ufually reckon on two pounds of lofs ; but we can fay, with the utmofl confidence, that the aftual lofs is rather lefs than we have flated it. A correfpon- dent of ours, on whofe accuracy we can depend, weigh- ed, in 1795, two bufhels, Winchefler meafure, the one of white and the other of red wheat, and found the weight of them both to be 132 lb. This wheat was ground by his own fervants, and it yielded I2l4-lb. of meal, fo that there was here but i lb. loff of two bufh- els, or of 122 lb. in grinding. He admits that he fuflfer- cd the ftones to turn too clofe, and that the lofs fliould therefore have been fomewhat greater. The meal was dreffed, as the wheat had been ground, under his 6wii eye ; and every poffible precaution being taken to pre- vent his being deceived in the refult, he had of flour, or /econds, p^llb. and of bran and pollard 2 5|lb. ; fo that he loft, of two bufhels, but 2i lb. both in grinding and 4 ] B R E drcflTing. The ofFal, or bran and pollard, being drefled in a bolting mill, yielded as follows : ' Sliarps - 6 lb. o oz. Fine pollard 5 8 Coarfe pollard 7 8 Broad bian 5 8 Bread. Altogether 24 8 There was loft, therefore, in bolting, only one pound; and of the fharps, about three pounds, if fifted, would have been good flour. Indeed were the fharps and fine pollard to be added to the flour, the bread would, per- haps, be better, and more wholefome, than without fuch addition. From thefe data, which we believe to be very accurate, it will be eafy to calculate, if the price of wheat be given, what fhould be the price of flour per bulhel and peck, the price of bread per pound, and the quantity of bread that fhould be fold for a fhllling. It is a faft, however, which fliould be attended to, that loaves are not always of the fame weight, though made of equal quantities of the very faine dough. This was fully afcertained fome years ago at Paris. On a violent complaint that the bread was not always of the fame ftandard weight, the bakers of the city were cal- led before the police officers. They admitted the faft, that loaves, baked at the fame time, and in the fame oven, were feldom, if ever, of the fame weight ; but they infilled that they contained, each, the ftandard quantity of dough, and that the variety of weight among them muft proceed from fome caufe, which they did not pretend to afcertain. The matter was refer- red to the Royal Academy of Sciences, which appoint- ed one of its members to fuperintend, for fome days, the whole procefs of baking. This being done, it was found that, of loaves baked in a large oven, thofe were always heavicft which occupied the centre of the oven, and that the bakers were innocent of the crime with which they were charged. The faft, we think, may eafily be accounted for. Even in an oven there mufl be fome condenfation of fteam ; and, from the very fhape of the oven, the greateft quantity muft be con- denfed towards the centre. Hence the loaves in the centre are neceffarily wetter and heavier than thofe round the circumference, if the plain of the oven has been equally heated. Brf.ad of Rice might occafionally be of great ufe in many countries during a fcarcity of wheat ; but the method of making it is not generally known. It is in- deed impoflible to make bread of the flour of rice, which is harfli and dry like fand or afhes, by treating it in the manner in which wheat-flour is commonly treated; and therefore it has been propofed to mix it with an equal quantity of the flour of rye. But this method of ufing the flour of rice is a very uncertain remedy in cafe of want; fince we can have no rice-bread if we have not rye. We are taught, however, in the 'Journal des Sci- ences, des Letlres, et des Arts, how to make excellent bread from rice alone, by a method which the author of the memoir fays he learned from the natives of A- merica. According to this method of making the wiilied-for bread, the firft thing to be done to the rice is, to re- duce it to flour, by grinding it in a mill, or, if we ha\-c not a mill, it may be done in tha following manner: Let Brfsd, B R R [115 Let a certain quantity of water be heated In a fiuce- pan or caldron ; when the water is near l)oihn{^, let the ~ rice we mean to reduce into flour be thrown into it : tiie velTel is then to be taken off the fire, and the rice left to foak till the Jicxt morning. It will then be found at the bottom of the water, which is to be poured off, and the rice p\it to drain upon a table placed in an in- clined pofition. When it is dry, it mull be beat to powder, and paffed through the fined ficve that can be procured. When we have brought the rice into flour, we muft take as much of it as may be thought neceffary, and put it into the kneading trough in which bread is ge- nerally made. At the fame time we muft heat fome water in a faucepan or other veficl, and, having thrown into it fome handtuls of rice, we mull let them boil to- gether for fome time : the quantity of rice muft be fuch as to render the water very thick anil glutinous. When this glutinous matter is a little cooled, it mull be poured upon the rice-flour, and the whole muft be well kneaded together, adding thereto a little fait, and a proper quantity of leaven. We are then to cover the dough with warm cloths, and to let it ftand that it may rife. During the fermentation, this pafte (which, when kneaded, muft have fuch a proportion of flour as to render it pretty firm) becomes fo foft and liquid that it feems impolfible it fliould be formed into bread. It is now to be treated as follows : While the dough is rifing, the oven muft be heated ; and, when it is of a proper degree of heat, we mull take a ftewpan of tin, or copper tinned, to which is fixed a handle of fufficient length to reach to the end of the oven. A little water muft be put into this ftew- pan, which muft then be filled with the fermented palle, and covered with cabbage or any other large leaves, or with a flieet of paper. When this is done, the ftew- pan is to be put into the oven, and pufhed forward to the part where it is intended the bread (hall be baked; it muft then be quickly turned upfide down. The heat of the oven a6ls upon the pafte ia fuch a way as to prevent its fpreading, and keeps it in the form the ftewpan has given it. In this manner pure rice-bread may be made ; it comes out of the oven of a fine yellow colour, like paf- try which has yolk of eggs over it. It is as agreeable to the tafte as to the fight ; and may be made ufe of, like wheat-bread, to put into broth, &c. It muft, how- ever, be obferved, that it lofes its goodnefs very much as it becomes Hale. It may be here remarked, that the manner in which Indian corn is ufed in fome countries, fOr making bread, can only produce (and does in fa£l produce) very bad dough, and of courfe very bad bread. To employ it advantageoufly, it Ihould be treated like rice ; and it may then be ufed, not only for making bread, but alfo for paftry. BREWING is an art of vaft importance, and has accordingly been explained in the EncyclopiEdia Bri- tannica. A few improvements, however, have been made in the art, which, though not noticed in that Work, feem to be worthy of general attention, and, therefore, to deferve a place in this Supplement. The lirft, of which we fliall give an account, is an invention of Mr William Ker of KerfieU, in the county of Tweedale, for the faving of hops, and, at the fame ] K II E time, giving to the liquor, whether ale, beer, or porter, a fupcrior flavour and quality. The fteam which aril'es from the boiling copper is known to be ftrongly impregnated with the effentlal od ot the hops, in which their flavour confifts. In- ftead, therefore, of allowing it to tfcape and evaporate, as it does in the common mode of brewing, Mr Ker contrives to preferve and condenfe it, by means of a winding-pipe fixed to the copper, fimilar to the worm of a ftill, or by a ftraight pipe pafling through cold water, or any other cooling medium. The oil and wa- ter, thus obtained, are returned Into the worts when boiled, or the oil, after being feparated from the water, along with which it had been exhaled, is returned into the worts after they are boiled ; and the watery part, which, after the oil is feparated, ftill continues impreg- nated with the aromatic tafte and bitter of the hop, is returned into the next copper or boiling-vefl'el ; and fi> on from one copper or boiling-veflel into another. By this procefs a confiderable part of the hop and flavour, which is loft in the ordinary mode of brewing, is pre- ferved : the flavour of the liquor is improved by the prefervation of the finer parts of the aromatic oil : and the ale and beer are better fecured from any tendency to acidity or putrefaftion, and therefore muft be titter for home conl'umption and exportation. For thia inven- tion, vvhich is certainly fimple, and we think rational, Mr Ker obtained a patent, dated March 4. 1 ySK. On the 4th of June 1790, Mr John Long oi Long. ■o'llle, in the county of Dublin, Ireland, obtained a pa- tent for an improvement in brewing, refembling, in one particular, this invention of Mr Ker's. To his inven. tion, however, he gives the name of an entire new me- thod, in all the ejfent'tal parts, of brewing good malt li- quor ; and therefore, as it comprehends the whole pro- cefs of brewing, we ftiall lay it before our readers in the words of its author. " I. For the better extrafting from malt, place near a mafti tun a Ihallow copper or other veflel that will readily heat ; the curb of which to be on a level with the tun, and to contain from two to fix hogflieads, ac- cording to the dimenlion of the tun, more or lefs; and, at the lower end of the copper, have a cock from two to five inches diameter, more or lefs, to condudl the heated liquor from the copper into a tube which paf- fes down the external part of the tun, and enters it through an aperture about fix inches from the bottom; then forming two revolutions, more or lefs, through the body of the tun, and communicating its heat to the wort as it pafles through the tube; and then, at a con- venient dillance from the place it firft entered, it runs from the tun into a ciftern or tub, fituate as near as convenient to tlni copper or heatlng-velfel. In the tub or ciftern is to be placed a pump, for the purpofe of conveying the cooler liquor back to the copper or heat- ing-vcffel again ; there to receive the heat of 208 de- grees, more or lefs (which it will require after the firll half-hour), and then convey it through the mafliing-tun as before, and in the fame manner, as long as the work- ing brewer or dilliller may think neceflary, to raife the mafliing tun to any degree of heat required. By ad- hering to the foregoing procefs, the lirft liquor may, with the greateft fafety, be let upon the malt from 20 to 30 degrees lower than the prefent praftice ; by which means it operates with gentlenefs, opens and ex- P 2 panda Brrwing. B R E [ ii6 ] B R 1 Brewing, pands the malt and raw corn, and prepares it for the '""'"^'""^ reception of fharper or warmer liquor, fo as to extraft the whole of the facchariiie quality from the malt and raw corn. By the foregoing method, the mafliing-tun, inllead of loliiig its firil heat (which it does by the prelent praiftioi:), continues to iiicrcafe in heat every moment, by conveying the heated liquor through the tube into the tun ; by which means, at the end of two hours, the working brewer or dilliller can have the tun brought to any degree of heat he niall think bed fuited to the diflertnt qnahties of the rnait or raw corn. Per- fons wiio would wilh to fave expence, may heat their malhing-t>in at the fide or bottom by a large piece of metallic fubtlance made fire proof, and fixed therein ; which, in fome degree, will anfwer the end propofed, but with great trouble and delay. " 2. To prevent the wort from receiving a difagree- able flavour while in the under-back, a tube muft be placed at the cock of the madiing-tun, to receive the wort as it comes off, and convey it to a great cittern or refrigeratory, which is fupplied with a ftream of water. The wort, paffing through that medium in a fpiral tube, foon lofes that heat which fo often proves prejudicial to the brewer and diftiUer in warm weather: then pafs it from the tube into a veflel in which pumps are placed, to return the worts into the copper for the purpofe of boiling off. All veffels for receiving the cold wort muft be placed lower than the fource whence the wort comes. «' ^. As the great objeft of long boiling the wort is remedied, by my invention of taking the extradl from the hops in a feparate manner from the worts, I boil my worts no longer than from 1 5 to 20 minutes ; and, by purfuing that method, 1 fave much time and fuel, and regulate my lengths accordingly. _ «« 4. I fteep my hops, the preceding day to which they are to be ufed, in a copper or other veffel, with as much fluid, blood-warm, as will cover the hops, where it is to remain over a flow fire at leaft 14 hours, clofe covered ; the copper at the tenth hour not to be of a greater heat than 175 degrees, continuing flow until the lad hour. Then I bring the copper gradually to a fimmer or flow boil ; in which ftate I let it remain about 10 minutes, and then run off the fluid ; and this 1 do at the fame time the firft wort is boiled oft", that they may both pafs together through the refrigeratory into the fermentation or working tun. After the fore- going operation, I cover the hops again with other li- quor, and bring the copper to boil as foon as conve- nient, and let it remain in that ftate a confiderable time, until the fecond worts are boiled off. Then I pafs the hop-fluid with the wort, the fame as in the firft inflance ; and, if there is a third wort, I boil my hops a third time with fmall worts, and pafs it off as before ; by which means I gradually obtain the whole of the effential oil and pleafing bitter from the hops, which is effeftually prefervcd in the beer, " r. To cool worts. When the wort is boiled off, it is conduced from the cock of the copper or boiler into a tube of a proper dimenfion, which paffes the wort from the cock to the large ciflern or refrigerato- ry, and there performs feveral revolutions, in a fpiral manner, through the fame tube ; which is immeifed in conftant fupply of cold water, where it lufes the greateft Tart of its heat in a fliort time, and tkence continues a ftraight courfe tlirough the tube, a little elevated and Brewing of a fuitable length, placed in brick-work, until it meets . II a fmall refrigeratory, fupplied with colder water from a . """''^X' rcfervoir made for that purpofe at the head of the works ; whence a continual flream runs on the furface of the tube down to the great refrigeratory, cooling the wort as it paffes, in order to enable the working brewer or dilliller to fend it into the backs or working, tuns at whatever degree of heat he fhall think proper. There is no other difference between brewer and difliller in this procefs, but that the difliller immediately paffes the ttrong wort from the mafliing-tun to the back, thro' the fame machinery above inferted, and the tubes may be made of lead, or any other metallic fubllance. " 6. To enable me to brew in the warm fummer months, I fink my backs or working-tuns at leaft to a level with the ground, but if deeper the better, and co- ver thein clolely by an arch made of bricks, or other materials, that will totally exclude the atmofpheric air from them. I place them as near as poffible to a fpring or fand-drain, as their depth will naturally draw the wa- ter thence, which muft be fo contrived as to pafs or flow round the backs or tuns. I then introduce a large tube, which paffes through the tuns, and keeps the wort feveral degrees lower than can poffibly be done by the prefent prattice ; by which means I can produce a complete fermentation even in the dog-days. " 7. In cold or frofty weather, if the tun and backs Ihould lofe the firft heat, intended to carry it through the procefs by the foregoing method, you may convey a fupply of warm or boKing water by the tube, which paffes through the body of the backs or tun, communi- cating its heat, which rifes to any degree the working brewer fhall think proper : by purfuing this method, in the coldefl feafon, I never want a fermentation." We regret that we cannot wilh propriety ftate to our readers, under this article, a fummary of Mr Rich- ardfon of Hull's Philofophical Principles of Breiving ; for as the author has a new edition of his work in the prefs, it is our duty rather to refer to it, than to quote from a former edition, which contains not his laft im- provements. See Feriwentation and Malt, in this Supplement. BRIDEALE. See Scotale in this Supplement, BRIDGE. See that article (Encycl.J, and Arch in this Supplement. A luooden-hriA^K, of large fpan, fhould be conftrufled on the principles explained under the title Roof [Encycl.) See alfo Centre {^Suppl.) BRINDLEY (James), was born at Tunfted, in the parifli of Wormhill, Derbyftiire, in 1716. His fa- ther was a fmal! freeholder, who diffipated his property in company and field amufements, and neglefted his fa- mily. In confequence, young Brindley was left defti- tute of even the common rudiments of education, and till the age of 17 was cafually employed in ruftic la- bours. At that period he bound himfelf apprentice to one Bennet, a mill-wright at Macclesfield, in Chefhire, where his mechanical genius prefently developed itfelf. The mafter being frequently abfent, the apprentice was often left for weeks together to finifli pieces of works concerning which he had received no inftruftion ; and Bennet, on his return, was often greatly aftonifhed to fee improvements in various parts of mechanifm, of which he had no previous conception. It was not long before the miilers difcovered Brindley's merits, and pre- ferred. B R I Brindley. ferred tiim in the execution of tlieir orJers to the maf- •" V ' ter or any other workman. At the expiration of his fervitude, Ben net being grown into years, he took the management of the bufmefs upon himfelf, and by liis fliill and indullry contributed to fupport liis old nudler and his family in a comfortable manner. In procefs of time Brindley, fet up as a mill-wright on his own account ; and by a number of new and in- genious contrivances greatly improved that branch of mechanics, and acquired a high reputation in the neigh- bourhood. His fame extending to a wider circle, he was employed, in 1752, to ereft a water-engine at Clif- ton, in Lancafhire, for the purpofe of draining fome coal mines. Here he gave an eday of his abilities in a kind of work for which he was afterwards lo much dillin- gui/hed, driving a tunnel under ground through a rock nearly 600 yards in length, by which water was brought out of the Irwell for the purpofe of turning a wheel fixed ^o feet below the furface of the earth. In 17 J5 he was employed to execute the larger wheels for a lilk mill at Congleton : and another perfon, who was enga- ged to make other parts of the machinery, and to fu- perintend the whole, proving incapable of completing the work, the bulinefs was entirely committed to Brind- ley ; who not only executed the original plan in a maf- terly manner, but made the addition of many curious and valuable improvements, as well in the conftruftion of the engine itfelf, as in tlie method of making the wheels and pinions belonging to it. About this time, too, the mills for grinding flints in the Staffordlhire potteries received various ufeful improvements from his ingenuity. In the year 1756 he undertook to ereft a fteam en- gine, upon a new plan, at Newcaftle-under-Line ; and he was, for a time, very intent upon a variety of con- trivances for improving this ufeful piece of mechanifm. But from thefe deligns he was, happily for the public, called away to take the lead in what the event has pro- ved to be a national concern of capital importance — the projefting the fyftem of canal navigation. The Duke of Bridgevi'ater, who had formed his dcfign of carrying a canal from his coal-works at Worfley to Manchefter, was induced by the reputation of Mr Brindley to confult him on the execution of it ; and having the fagacity to perceive, and ftrength of mind to confide in, the ori- ginal and commanding abilities of this felf-taught ge- nius, he committed to him the management of the ar- duous undertaking. The nature of this enterprife has already been deferibed [Emycl. vol. IV. p. 8c.) ; it is enough here to mention, that Mr Brindley, from the very firft, adopted thofe leading principles, in the pro- jefting of thefe works, which he ever after adhered to, and in which he has been imitated by all fucceeding artifts. To prefeuve as much as polhble the level of his canals, and to avoid the mixture and interference of all natural flreams, were objedls at which he conftantly aimed. To accomplifh thefe, no labour or expence was fpared ; and his genius feemed to delight in over- coming all obllacles by the dilicovery of n^w and ex- traordinary contrivances. The moft experienced engineers upon former fyftems were amazed and confounded at his projedts of aque- duft bridges over navigable rivers, mounds acrofs deep valleys, and fubterraneous tunnels ; nor could they be- lieve in the prafticability of fome of thefe fchemes till [ i'7 ] B R I they faw them effrftcd. In the execution, the ideas Brindley. he followed were all his own ; and the nilnnteft, as well *'~~v— as the greatell, of the expedients he employed, bore the llamp of oiiginality. Every man of genius is an en- thufKill. Mr Brindley was an enthufiail in favour of the fupcriority of canal navigations above thofe of ri- ' vers ; and this triumph of art over nature led him to view with a fort of contempt the winding flream, in which the lover of rural beauty fo much delights. This fentiment he is fiiid to have exprefTed in a llrikiTig man- ner at an examination before a committee of the Houfe of Commons, when, on being afked, after having made fome contcmpttious remarks relative to rivers, wliat he conceived they were created for? he anfwered, " to feed navigable canals." A diretl rivalry with the naviga- tion of the Irwell and Merfey was the bold cnterprize of his firlt great canai ; and fince the fuccefs of that defign, it has become common, all over the kingdom, to fee canals accompanying, with infulting parallel, the courfe of navigable rivers. After the fuccefsful execution of the Duke of Bridge- water's canal to the Merfey, Mr Brindley was employ, ed in the revived defign of carrying a canal from that river to the Trent, through the counties of Cheller and Stafford. This undertaking commenced in the year 1766 ; and from the great ideas it opened to the mind of its conduilor, of a fcheme of inland navigation which (hould conneft all the internal parts of England with each other, and with the principal fca-ports, by means of branches from this main item, he gave it the empha- tical name of the giand trunk. In executing this, he was called upon to employ all the refources of his in- vention, on account of the inequality and various na- ture of the ground to be cut through : in particular, the hill of Harecallle, which was only to be pafTed by a tunnel of great length, bored through flrata of dif- ferent confiftency, and fome of them mere quickfand, proved to be a mofl difficult, as well as txpenfive, obllacle, which, however, he completely furmounted. While this was carrying on, a branch from the grand trunk, to join the Severn near Bewdly, was committed to his management, and was finifiied in 1772. He alfo executed a canal from Droitwieh to the Severn ; and he planned the Coventry canal, and for fome time fu- perintended its execution ; but on account of fome dif- feience in opinion, he refigned that office. The Chcf- terfield canal was the lad undertaking of the kind which he conduced, but he only livedno finifli fome miles of it. There was, however, fcarcely any defign of canal- navigation fet on foot in the kingdom, during the lat- ^ ter years of his life, in which he was not confulted, and the plan of which he did not either entirely form, or revife and improve. All thefe it is needlefs to enu- merate ; but, as an infl;ance of the vaftnefs of his ideas, it may be mentioned, that on planning a canal from Li- verpool to join that of the Duke of Bridgewater at Runcorn, it was part of his intention to carry it, by an aqueduA bridge, acrofs the Merfey, at Runcorn Gap, a place where a tide, fometimes rifing fourteen feet, rufties with great rapidity through a fudden contraAion of the channel. As a mechanic and engineer, he was like- wife confulted on other occafions; as with refpeft to the draining of the low lands in different parts of Lin- colnfhire and the Ifle of Ely, and to the cleanfing of the docks of Liverpool from mud. He pointed out z. method,. B 11 I , [II Brindley. mttliod, which has been fuccefsfully pradlifcd, of build- '^'~^'~~~ iiig fea-walls without mortar ; and he was the author of a very ingenious improvement of tlie machine for drawing water out of mines by the contrivance of a lo- . iiiig and a gaining bucket. The intenfity of apph'cation which all his various and complicated employments required, probably shortened his days ; as the number ot his undertakings, in fome degree, Impaired his ufefulnefs. He fell into a kind of clironic fever, which, after continuing lome years, with little intermifiion, at length wore out his frame, and put a period to his life on September 27. 1772, in the 56th year of his age. He died at Tunhuvft, in Staffordihire, and was buried at New Chapel in the fame county. "In appearance and manners, as well as in acquire- ment, Mr Brindley was a mere peafant. Unlettered, and rude of fpeech, it was eafier for him to devile ■ means for executing a defign than to communicate his 'ideas concerning it to otiiers. Formed by nature for the profefiion he affumed, it was there alone that he was in his proper element ; and fo occupied was his mind with his bufinefs, that he was incapable of relax- ing in any of the common amufements of life. As he had not the ideas of other men to affift him, whenever a point of difficulty in contrivance occurred, it was his cuftom to retire to his bed, where, in perfeft folitude, he would lie for one, two, or three days, pondering the matter in his mind till the requifite expedient had pre- fented itfelf. This is that true infpiration which poets have almoft exclufively arrogated to themfelves, but which men of original genius in every walk are actua- ted by, when, from the operation of the mind adling upon itfelf, without the intrufion of foreign notions, they create and invent. A remarkably retentive memory was one of the ef- fential qualities which Mr Brindley brought to his men- tal operations. This enabled him to execute all the parts of the mod complex machine in due order, with- out any help of models or drawings, provided he had once accurately fettled the whole plan in his mind. In his calculations of the powers of machines, he followed a plan peculiar to himfelf ; but, indeed, the only one he could follow without inflruftion in the rules of art. He would work the queftion fome time in his head, and then fet down the refnit in figures. Then taking it up in this ftage, he would again proceed by a mental operaiion to another refult ; and thus he would go on by ftages till the whole was finifhcd, only making ufe of figures to mark the feveral refults of his operations. But though, by the wonderful powers of native genius, he was thus enabled to get over his want of artificial method to a certain degree ; yet there is no doubt that when his concerns became extremely complicated, with accounts of various kinds to keep, and calculations of all forts to form, he could not avoid that perplexity and embarraflrnent which a readinefs in the proccfl'es carried on by pen and paper can alone obviate. His eftimates of expence have generally proved wide of rea- lity ; and he feeras to have been better qualified to be the contriver, than the manager of a great defign. His moral qualities were, however, highly refpedlable. He was far above envy and jealoufy, and freely communi- cated his improvements to perfons capable of receiving and executing them ; taking a liberal fatisfaftion in forming a new generation of engineers able to proceed 8 ] B R I with the great plans in the fuccefs of which he was fo E iSit, deeply iiiterefted. Hii integrity and regard to the ad- '~~V—" vantage of his employers were unimpeachable. In fine, the name of Brindley will ever keep a place among that fmall number of mankind who form eras in the art or fcience to which they devote jhemfelves, by a large and durable extenfion of its limits. BRISSOT (J. P.), acted fo confpicuous a part in the French revolution, that a fair detail of the principal events of his life would undoubtedly be acceptable to all our readers. A fair detail, however, of fuch a life, we believe it impoflible at prefent to give ; for charafters like Briffot's are almoft always mitrcprefcnted both by their friends and by their enemies ; and till the troubles which they have excited, or in which they have been engaged, have long fubfided, the impartial truth is no- where to be found. In a fulfome panegyric, under the denomination of The Life nf J. P. Brijfot, faid to be written by himfelf, \v.e are told, that he was born January 14. 17^4 ; and that his father was a tra'iteur, or " the keeper of an eating-houfe," but in what place we are not informed. Our author, however, affures us that the old man was in eafy circumftances, and that he employed all the means refulting from them to give to his numerous fa- mily a good education. The fubjeft of this memoir was intended for the bar ; but not relilhing the ftudies neceflary to fit him for the profeflion of the law, or, if we choofe to believe him, having a mind too pure and upright for the ftudy of chicane, he relinquilhed the pur- fuit after five years of drudgery ! To relieve his wearinefs and difguft, he applied him- felf, he fays, to literature and the fciences. The ftudy of the languages was above all others his favourite pur- fuit. Chance brought him acquainted with two Eng- liftimen on their travels through France : he learned their language ; and this circumftance, he tells us, de- cided his fate. " It was at the commencement of my pafiion for that language (continues he) that I made the meta- morphofis of a diphthong in my name which has fince been imputed to me as fo heinous a crime. Born the thirteenth child of my family, and the fecond of my brothers in it, I bore, for the fake of diftinftion, ac- cording to the cuftom of Beauce, the name of a village in which my father pofieffed fome landed property. This village was called Ouarvilk, and Ouarville became the name by which I was known in my own country. A fancy ftruck me that I would cart an Englilh air up- on my name ; and accordingly I fubftituted, in the place of the French diphthong ou, the lu of the Engliih, which has precifely the lame found." For this pu- erile afFeClation, which was certainly not criminal, he _ juftifies himfelf by the example of the literati of the 16th and 17th centuries, who made no fcruple of Gre- cifing and Latinifing their appellatives. Having profecuted his ftudies for two years, he had an application from the Englifh proprietor of a paper then much in circulation, and intitled Le Courier de /' Europe. This man having drawn upon himfelf an at- tack from government, felt and yielded to the neceflity of printing his paper at Boulogne-fur-mer. It was his with to render it interefting to the French in the depart- ment of mifcellaneous intelligence ; which he therefore wilhed to fubmit to the fuperintendency and arrangement of B R I Briffot. of BrilTot, who reprefents hfmfclf as for fome moments ■— « ' heikiting. The profcdion of a journallft, fubjccl to a li- ceiifcr, was repugnant to his principles ; yet it lecured his independence, and put into his power the means of profecuting an inveftigation of conllitutions and of the fciences. After fome ridiculous reaioning from the ori- ginal ftations of Bayle, Pojld, and Roufflau, he at lad accepted of the employment, and became enamoured of it, " becaufe (fays he) it enabled me to ferve talents and virtue, and, as it were, to inoculate the French with the principles of the Englilh conftitution. This employment, however, did not laft for any length of time. The plan of the proprietor of the Cou- rier was overthrown by adminiflration, and Briflot quit- ted Boulogne to return to his iirft ftudies. Having in- formed us of this fail, he makes an extravagant pre- tence to unfuUied virtue, and calls upon the inhabitants of the city which he had left to bear witnefs, not only that he had no -vices, but that he had not even the feeds of any one of the vices which his adverfaries, it fecms, had laid to his charge. " Doubtlefs (fays he), too eager to publifh my ideas, I conceived that the proper moment had arrived, and I felt an inclination to commence with an important work. Revolting, from the very inftant of my beginning to re- fleft, againft religious and political tyranny, I folemnly protefted, that thenceforward I would confecrate my whole life to their extirpation. Religious tyranny had fallen under the redoubled llrokes of RoufTeau, of Vol- taire, of Diderot, and of D' Alembert. It became ne- ceflary to attack the fecond ;" and this was a taflc which the vanity of Briflot led him to confider as refer- ved for him. What Voltaire and his friends meant by religious ty- ranny, and how they condufted their attacks againft it, are matters, alas ! too well known to all Europe ; and as our author cliofe thefe philofophers for his guides, we might infer, without much degree of miitake, what he underllood by political tyranny, and by what means he meditated its extirpation. But he has not left us to make this difcovery by inference. " It became neceifary (fays he) to break In pieces the political idul, which, under the name of vwnarchy, praflifed the mod violent dcfpotifm ; but to attack it ppenly, was to expofe the aflailant without the polfibili- ty of ferving mankind. It was by a fide blow that it was to be wounded moft: efFeftually ;" and therefore he refolved to begin his operations by attacking fome of thofe abufes which might be reformed without apparent- ly (baking the authority of the prince. Our readers, at lead the fober part of them, will pro- bably think that this mode of attack is not peculiar to Briflot, but that it has been praflifed, or attempted to be put in praftice, by afpiring demagogues in all ages and countries, who have uniformly begun their career of innovation by exciting the public mind againft thofe abufes in government, of which the exiftence cannot wholly be denied. The fnbjeft to which our author thought fit to call the attention of liis countrymen, was the criminal jurifprudence : a fubjedt, fays he, which, with the exception of fome particulars that had been fuccefsfully inveftigated by Beccaria and Servan, no ivriterhad thoroughly confidcred in a phlloiophical point of view. Thinking himfelf fully equal to this tallc, he drew up a general plan ; and in the year 1780 publifl^- [ 119 ] B R. I ed his Theory of Criminal Laws, in two vols 8vo. This BrlTot. work, favourably received by foreigners, applauded by "—>"■"■ fome journalifts, and pulled to pieces by others, procu- red him the friendftilp of the warmeft advocates for hu- man liberty, in whofe opinion the dtfefts of his plan were highly pardonable, on account of the energy con- fpicuons in his remarks. This publication was fooii followed by two dlfcourfes which gained the prize in 1782 at the academy of Chalons-fur-Marne ; the one upon the reform of the criminal laws, and the other on the reparation due to Innocent perfons unjuftly accufcd. It is natural to fuppofe that the government beheld with an evil eye thefe writings, which, under pretext of dragging into light the abufes of the criminal laws, infinuated dangerous principles on the nature of govern- ment In general. His next work was intltlcd, A Philofopkical Library of the Criminal La-Ms, In 10 vols; the true objedl of which was to difrcminate in France thofe principles of liberty which guided the Engllfh and the Americans In framing and expounding their laws. But the ftudy of iegiflation and politics had not en- tirely drawn him off from that of other fciences; fuch as chemiltry, phyfics, anatomy, theology, &c. Thefe he conftantly cultivated with ardour ; but acknowledges that In each he met with obfcurities, and that in eveiy quarter truth cfcaped from his refearches. He there- fore fat down to inveftigate the nature of truth, and the proper method of attaining to it in every depart- ment of refearch ; and the refult of his labours was a kind of novum organum, by which he feems to have ex- pected that Bacon's work would be burled In oblivion ; and to this Important volume he gave the title of Con- cerning Truth ; or. Thoughts on the Means of attaining Truth in all the Branches of Human Knowledge. This volume was meant as nothing more than the introduc- tion to a greater work, in which he propofed to invefti- gate what is certain In knowledge and what doultful, and then to ftrike the balance of the account. He was prevented, however, from completing his plan, which he regrets exceedingly ; for, as he affirms, with becoming modejly, his work would certainly have amended Its readers ! But the French government ha])- pened to think otherwife ; his aim, which, he fays, was to lead mankind to refloft on their rights, was perceived, and he was accufed to the m.ialfter as a fedit ions- writer. The career of genius was ftopped by the dread of the Baftlle ; and he was obliged to take refuge in London. There It was his widi to create a univcrfal confederation of the friends of liberty and truth, and to eftablifh a centre of correjpondem e and union with the learned and the politicians of Europe. This dark dtiign, however, was fruftrated by the treachery, as it would appear, of his affoclates, who had bound themfelves, he fays, by the \x\Q^facred oaths, to alTift him, and had offered to- fign articles even ivith their own Hood. Finding himfelf unable to proceed diredly to the ob- jeft which he had in view, he refolved to enliglteii his countrymen gradually, and to begin with exciting their love and admiration of the Englifli conftitution. That conftitution, which he had Inveftigated on the fpot, ap- peared to him a model for tliofe focleties which were defirous of changing their form of government. Tt was but little known, he fays, in France (the work of De Lolme being at that time only in. the hands of the learn- ed); B R I [ BrtlTit. eJ); and to make it known was to make it beloved, was V ' to render it delired. But the Frencli minifters Hood upon their guard, and it became neceflary to deceive them. He refolved therefore to bring forward a jour- nal written adually in London, and profelTing to con- tain only a dcfcription of the fctences and arts of England, wbilil the greater part of it was to be occupied in rea- lity by an inveftigation of the Englijh conjlitulion. After many difficulties, the minillry granted a privi. lege for this journal, being publifhed in London, to be reprinted in Paris; and it firft appeared in 17S4. " In the twelve numbers which have been publifhed (fays the author), the friends of liberty mull have perceived, that if, on the one fide, I endeavoured to inculcate more juft ideas than had hitherto been entertained concerning this celebrated ifland ; fo, on the other, I refolutely made my advances toward that important end which has perpetually prefided over all my labours, the unlverfal emans:/<.it'nn of m'-n." His affairs calling him at this time to Paris, he was arrelled and conveyed to the Baftile on the 12th of July 1784. In this conduft of the government we cannot perceive any thing very tyrannical or arbitrary, fince he confefies, that, in the i6th page of the firft number of his Journal, he had fufFered the fecret and fa- vourite aim, which always guided his pen, to become difcernible. He was, however, difcharged from prifon on the ;th of September, and returned with increafed zeal to his former employments. "This perfecution (fays he), far from extinguifhing the ardour of my wiflies to inculcate the principles of freedom, ferved only to inflame it the more." Accord- ingly, in 1785, he publiflied two letters to the Empe- ror Jofeph II. concerning the right of emigration, and the right of people te revolt. The firil of thefe letters, which, though well known in Germany, were in France fup- prefied by the police, was occafioned by what the au- thor calls the ridiculous and barbarous edift again ft emigration ; and the fecond by the puniftiment of Ho- rlah the chief of the IValachian infurgents. In this hft letter he lays it down as a maxim, that all people under fuch a government as that of the IFa/achlans, have from nature a facred rlghl to revolt, a right wliich they can and ought to exercife. In the fame fpirit he brought out, in 1786, his Philofophical Letters on the Hiftory of England, in 2 vols, and A Critical Examination of the Travels of the Marquis de Chatelleux in North A- merica. The French revolution appearing to him extremely diftant, notwithftanding all his efforts to haften it, he refolved to leave France for the purpofe of fettling in America. His projefl received the approbation of fe- veral, whofe fentiments were congenial with his own. But as it was thought imprudent to tranfport numerous families to a country fo far off, without thoroughly knowing it, BrifTot was engaged to proceed thither, to examine the different places, to obferve the inhabitants, and to difcover where and in what manner the eftablifh- ment they had propofed might be moll advantageoufly fixed. He had fome time before inftituted a fociety at Paris for accomplifhing the abolition of the negro trade, and for foftening the condition of the flavesi. At the period of his departure, this fociety confifted of a con- fiderable number of dlllinguifhed members, and he was commiflioncd to carry the firft fruits of their labours to 20 ] B R O America. His ftay there, however, was not fo long as he was deflrous of making it. In the beginning of 1789 he was recalled by the news of the French revo« lution, which he conceived might probably produce a change in his own meafures and in thole of his friend^. This idea, added to other circumftances, accelerate'd his return. The fire had blazed forth in his native coun- try. " Hope (fays he) animated every heart ; the moft diftinguifhed champions had engaged in the contell ; I too became defiious to break a Lince, and I publifhed my P/cjn of Conduct for the Deputies of the People." This, and other works of a fimilar kind, of which he loudly boafts the merits, raifcd him high in the favour of tlve republican part of the nation, and he became prefident of his diftric^ ; where he afted, according to his own account, with great uprightnefs in the munici- pality, in the firft committee of inquiries, and as an eledlor. At laft he became a member, firft of the Na- tional Affemhly, and, after its dilTolution, of the SanguU nary Convention ; and by fome means or other got to be the leader of a party called fometimes the Girondljls, and fometimes the Brljfotlnes. From that period the principal events of his life were involved with the pub- lic tranfadlions of the nation, of which we have given an account in the Encyclopedia under the title Revo- lution (fee that article, n" 101 — 182.) The Giron- dift fadlion was denounced by the Mountain, and Brif- fot fuffered by the guiUotine on the 30th of November 1793. He fell indeed by a very unjuft fentence ; but his fall was the natural confequence of that anarchical tyranny under which no man had contributed more than he to fubjeft his native country. BROWN (Dr John), author of the Elementa Medi- cine, &c. was born in the viUage of Dunfc, or, as fome fay, Lintlaws, in the county of Berwick, in the year 1735-6. His paren'.s were of mean condition, but much refpefted in the neighbourhood for the integrity of their lives. His father gained his liveliliond in the humble capacity of a day-labourer ; while his mother contributed her fliare towards the fupport of the fami- ly by the profits arifing from a milch cow. Such were the perfons who, in an obfcure part of the country, gave birth to a Ion deftined, at a future period, to make a diftinguifhed figure in the republic of letters ; and from whom originated a fyftem of the ani- mal economy, wliich, whatever be its real merits, has undoubtedly produced a confiderable revolution in the practice of medicine. At the age of three or four years, young Brown was put to a reading fchool in Dunfe, which he himfelf commemorates as the place rather of his education than of his nativity. Here, under the tuition of an old wo- man, he very early began to exhibit inarks of that ftrength of mind for which he was afterwards fo emi- nently diftinguifhed. In the (hort period of a year he became able to read with facility any part of the Bible, and acquired over his clafs-fellows that fuperiority which he ever after maintained both at fchool and college. It was almoft immediately after his entrance into this fchool, that his infatiable defire of reading commenced; and fo unremitting was his application, that he is faid never to have been found, even at thofe hours which children much more advanced in life devote to amufe« ment, without a book in his hand. While he was making this rapid progrefs in the ru- dimentt B R O [I Brown, diments of literature, he fuffered what fnuft have ap- ■"v""- peared to be a very heavy lofs in the death of lu's fa- ther ; but his mother foon afterwards married a worthy man of the fame name, whofe care and attention Inp- phed the place of a father to her fon. Tin's man being a weaver, defigned to educate his fon-inlaw to the fame bufmefs, and began to inftrudt him in his art when he was about nine years of age: but the tafte which young Brown had already acquired for letters, made him look with difguft on the infipid employment of a weaver. His ftep-father was no tyrant, and his mother was affec- tionate. They were both proud of the talents which at fo early a period of life had appeared in their fon, and they felt no inclination to ftruggle with the invin- cible averfion which he exprtfltd to the bufmefs for which they intended him. Another circumftance, however, contributed in no fmall degree to make them recal their original refolu- tion. They were both of that feft of religionifts which in Scotland are called Seceders (fee Seceders, EncycL); and it was fuggelled to them by fome perfons of their own perfuafion, who had remarked the uncommon abili- ties of the boy, that he might one day prove an able fupport and promoter of their tenets as a preacher. He ivas accordingly, much to his fatisfaftion, taken away from the bufmefs to which he had conceived fuch a diftafte, and fent to the grammar-fchool of Dunfe, which was taught at that time by a gentleman of the name of Cruickfhank, eminent for his grammatical knowledge. Here he appears to have fpent fome years with uncommon advantage and happinefs ; during which he was eftcemed by all the country round as a kind of prodigy. Like Johnfon, and many other men of the highell celebrity, he united in the fatpe perfon uncom- mon powers of mind, with no lefs ftrength of body, as indeed his appearance indicated ; and in his youth he enfured his own perfonal importance among his fchool- fellows, by excelling them not lefs in athletic exercifes than in the taflis prefcribed by their mailer. He was particularly fond, when a boy, of praftifing the pugiliftic art ; and indeed until the laft period of his life he was obferved by his friends always to view an exhibition of that kind with peculiar relifh. He alfo prided himfelf much in being a (lout walker ; and mentions his ha- ving in one day accomplilhed, when but fifteen years of age, a journey of fifty miles between Berwick-upon- Tweed and Morpeth in Northumberland. When far- ther advanced in life, he travelled on foot from four in the afternoon of one day to two in the afternoon of next day, with the fhort interval of one hour's reft I But as one of his biographers very juftly obferves, " we have feen that he could make a more rational ufe of his ftrength than merely to flake it againll time and DrBed- fpace *." 's- His early years while at fchool were marked by the moil rigid attachment to his feft. So ftrift indeed were his religious fentiments, if a boy of ten or elevefi can be faid to have any fentiments deierving to be called reli- gious, that he would have conceived the holding of any communion with the eftabhihed church as a kind of profanation. An event, however, happened, fome time between the eleventh and thirteenth years of his age, which produced a total and unexpeeltd revolution in his religious opinions. At a meeting of the provincial fynod of Merfe and Tiviotdale, he was prevailed upon, SupFL. Vol. I. Pan I. 21 ] B R O though not without mauifefting much reluiflance, to accompany a party of his fchool-fcllows to the parifli church of Dunfe. Tlie coniequence of this tranfgref- fion, as he liad dreaded, was an immediate funimons to appear before the fellion of the Seceding congregation; to which, through pride, not choofing to attend, in or- der to preclude a formal expulfion, he voluntarily abju- red their tenets, and openly avowed his apoftacy to the ellablifhment. All changes in religion whicli are not the confequence of candid invettigation are dangerous. He who leaves one fcA he knows not why, will quickly abandon, with as little reafon, that to which in a fit of paflion he had haftily joined himfelf. From the moment of his quit- ting the communion of the Seceders, Brown's religious ardour fuffered a gradual abatement ; and though, to pleale his mother, he continued to profecute his fludies with a view to the office of a clergyman in the church of Scotland, his opiniuns became daily more and more lax, and his life of courfe lefs and lefs regular. It was, however, a confiderable time before he admitted, in their full extent, thofe principles of irreligion which he afterwards avowed ; for upon his firft perufing the Ef- fays of Mr Hume, though his own zeal was then much cooled, he expreffed great indignation at their danger, ous tendency. At the age of twelve years he had been employed by Mr Cruickfhank asakindof ullierin the fchool of Dunfe; and that gentleman having declared that his knowledge of the Latin language was equal to his own, his fame as a fcholar was fo fpread over the country, that at the age of thirteen he was intrulled with the education of a gentleman's fon in the neighbourhood, when he quitted the fchool and his beloved mafter. In his new fit na- tion, liowever, he remained not long. Dr Beddoes con- jeftures, that to the ftiffnefs of pedantry he added the fournefs of a bigot, and was therefore a difagreeable in- mate of the family. That a boy of thirteen, proud of his talents, and prouder of his learning, fliould have the ftiffnefs of a pedant, is indeed extremely probable ; it was the natural confequence of the praife with which he had been honoured by Mr Cruickfhank : but there is reafon to believe that of his original bigotry few tra- ces now remained. The real caufe of his difniiifion from the family, we are affured, was his pride; and as it muft have been the pride of parts, it confirms the firll part of Dr Beddoes's conjedlure. It feenis he was much difpleafed that, when company were at dinner, he was not defired to remain after tlie cloth was removed ; and yet if he was then only thir- teen years of age, it is not eafy to conceive for what purpoie he fhould have ftaid. He could not polFibly know much of the world, or of any thing likely to em- ploy the convei fation of country gentlemen ; and wc cannut help thinking, that the mafter of the houfc would have treated his guefts with rudcnefs, had he de- tained among them a raw bov to lillen to every un- guarded expreffiou which migbt cfcape them over their wine. It would appear, however, that he was not un- willing to give the tutor of his fon an opportunity of difplaying his abilities, when furh fubjedts were intro. duced as he knew him to have lludied ; for a difpute having arilen, one day after Brown had retired to his own room, concerning the decrees of Providence, he fent to requefl his opinions on that abftrufe fubjeft. By CL 'he nrown. B R O [ 12 Brown, the meflenger Brown returned a verbal .infwer, that . " the decreis of Providence are very uiijuft, for having made blockheads lairds." Mr Cruicklhank had fome time before requefted him to return to tlie fituation which he had formerly held in the fchool of Dunfe ; and we cannot wonder that, immediately after making this infolent anfwer, he found it convenient to comply with his rcqueih He was now about fifteen, and he continued in the fchool till the 20th year of his age ; during which time, from the conftant habit of teaching the Latin and Greek lan- guages, he acquired a wonderful facility in reading both thefc languages, and in writing the former, though he wrote not with tarte. About this time it occurred to him that he might turn his claffical acquirements to more account, by be- coming a private teacher of languages in Edinburgh. To that city he accordingly repaired, where, while he obtained a livelihood as a teacher, he propofed at the fame time to purfue his theological iludies at the univer- fity. But an accident happened to him here which made him altogether change the plan he had come upon ; and the death of his mother, after a relidence of fome time in Edinburgh, abfolvedhim.as he thought,from the promife which he had made to her of appearing one day in the pulpit. Shortly after an unfuccefsful competition for one of the chairs then vacant in the high-fchool, an ap- plication was made to a friend of his for a proper per- fon to turn a medical thefis into Latin. Brown was recommended. He was limited to a certain time; with- in which it appeared fcarce practicable to perform the tafk. He accomplilhed it, however, and in fuch a ftyle of crrammatical correftnefs and purity as far exceeded the general run of fuch productions. On this being remark- ed to him by his friends, he obferved, " that he now knew his ftrength, and was ambitious of riding in his carriage as a phyfician." He therefore determined to apply himfelf with ardour to the lludy of medicine, to which this accidental circumllance alone direfted his at- tention. Accordingly, at the commencement of the next winter feffion, he addrcfled a Latin letter to each of the medical profeffors, and by them was prefented with tickets of admittance to their fcveral clafles. From fuch a favourable beginning, being of a very fanguine difpofition, he conceived the moil flattering expcclations of his future fuccefs ; and indeed for fome time he feems to have lived in affluent circumftances. His attainments were fo various, and in fuch requeft in Edinburgh, that as a fmgle man he could fcarcely fail to gain a competent living ; for during the lall five years of his refidence under Mr Crulckftiank, to a tho- rough acquaintance with ancient hiflory, he had added a very confiderable knowledge of mathematics; in which, among other branches of fcience, he never had any ob- jeftion to give inftruclions. In the acquifition of that variety of knowledge which he polTeffed, he was greatly affifted by a moll tenacious memory ; to the retentive- nefs of which an old fchool-fellow bears telliraony, by affirming, that " after once reading over the lefTon, con- fiding of two odlavo pages in Latin, he would lay afide the book, and preleft the whole over without miftaking a fmgle word." Brown, already in eafy circumftances for an indivi- dual, faw, or thought he faw, in the eftablifhment of a boardiuK-houfe for ftudeuts a refource which would en- 2 ^ B 11 o able him to maintain a family ; and in expeftatlon of Browo, realiling this profpecl, he married, in 1765, the daugh- '~~ ter of a rcfpeftable tradefman in Edinburgh. The di- ftiiiguifhed attention at that time paid him by Dr Cul- len, in whofe family he had become a neceflary perfon, contributed in all probability to llrengthen his hopes that his lioufe would be filled with proper boarders through the Doftor's recommendation. His fuccefs in this way for fome time anfwered his moft fanguine cx« peftations ; and his circumftances at one period were fo flourifhing, that he is faid to have kept a onc-horfe chaife. It was, perhaps, the greateft misfortune that could have befallen Brown, that he poifelTed, in a high de- gree, thofe talents which make a man's company fought after by the gay and the diffipated : He was capa- ble of " fetting the table in a roar." We need not therefore wonder at his frequently neglefting more neceffary purfuits to enjoy ttie conviviality of the nu- merous friends who courted his company; or that drink- ing and diflipation became habitual to him. He was as deficient in point of prudence as he excelled in ge- nius. His houfe was filled with refpeclable boarders ; but as he lived too fplendidly for an income at bell but precarious, he became gradually involved in debt, and his affairs were Hill more embarraffed by the burden of a nu- merous family. Soon after he began to be involved ia thefe difficulties, he fuffered an additional lofs in being deprived of the patronage of Dr CuUen, in confequencd of a difagreement that had taken place between them. This enmity, which had for fome time before fecretly fubfifted, probably Jrom mutual jealoufy, was at length excited into an open rupture ; firft, by Dr CuUen's not exerting his intereft in procuring for Brown the theo- retical chair of medicine, then vacant in confequence ei- ther of the death or refignation of Dr Alexander Monro Drummond; and, fecondly, by his rejecting, fome time, after. Brown's petition for admittance into the Edin- burgh Philofophical Society. In 1776 Brown was elected prefident of the Medicab Society ; and the fame honour v/as again conferred on him in 1 780. He was led on, in the gradual manner he himfelf defcribes in his mafterly preface to the Ek- menta Medtcina, to the difcovery of his new doClrine f. which, on dropping all correfpondence with his former friend and benefactor, he now, for the firft time, began to illuftrate ia a courfe of public leftures ; and in thefe he difplayed equal ingenuity and philofophical profun- dity. Much about the time of which we now fpeak^ he publifhed the firft edition of the Ehmenta Medkina ; a work which certainly proves its author to have been a man of uncommon genius and originality of thought. The circumftances in which this work was compoftd refleft great honour on his abilities. He never retired to his Itudy ; but, totally abforbed in his own ideas,. wrote with the greateft tranquillity amidll the noife of ten children, occafionally fettling their childilh dif- ferences. In the year 17791 though he had ftudied medicine ten or twelve years at the univerfity of Edinburgh, he was prevailed upon by his friends to take a degree at St Andrews, where he gave a confpicuous proof of his facility in Latin compofition. He wrote a thefis, or inaugural dilfertation, in the tavern while the cloth was laying for dinner ; and one of his companions, who was finging B R O [ »23 1 B R O fingiiig befide him, having uttered a falfe note, or fung out of time, Mr Brown, in the middle of his writing, flopped to (hew him how the fong ougiit to be fung, and then inilantly proceeded in his thelis. His family having now become fo numerous as to ren- der keeping a boarding-houfe inconvenient, he had alrea- dy for fume time given it up, and depended for lupport entirely on his praftice as a phyfician and his public ledlures. At this time the dii'putcs between the Culle- iiiaiis and the Brunonidiis (as the young men now llyled themfelvcs) were carried on with iuch acrimony on both fides, in the different focieties, that it was not unufual tor them to terminate in duels ; and there cxiils at this day, on the records of the Medical Society, a law which it was thought expedient to enadi, by which a member who challenges another for any thing laid in public de- bate incurs the penalty of expullion. Obferving the lludents of medicine frequently to feek initiation into the mytteries of freemafonry, Dr Brown thought their youthful curiofity afforded him a chance of profelytes. In 1784, he inftituted a meet- ing of that fraternity, and intitled it the Lodge of the Roman Eagle. The bufniefs was condufted in the La- tin language, which he fpoke with the fame fluency as Scotch ; and he dilplayed much ingenuity in turning into l.dtin all the. terms ufed in mafonry. As the terms on which he lived with his brethren of the faculty were fuch that hg, obftinately avoided meeting them even in confultatftin, we may conclude that his own private pra£lice was but limited. His friends affirmed, perhaps without iufficient proof, that cabals were formed againft him, and every advantage taken of the errors he was led to commit by his own imprudenc-e. After a long feries of itruggles, there- fore, hoping to meet with that encouragement among the Englilh uf which he had been dil'appointed in his own country, he put in praftice a plan upon which he had long meditated, and removed in 1786 with part of his family to London. Immediately on his arrival, an incident bcfel him, which Dr BeJdoes fays he has heard the late Mr Murray, bookfeller in Fleet-ilreet, relate as a proof of his fimplicity. The peculiarity of his ap- pearance as he moved along (a (hort fquare figure, with an air of dignity, in a black fuit, which heighten- ed the fcarlet of his checks and nofe) fixed the atten- tion of fome gentlemen in the flreet. They addrelTed him in the dialeft of his country. His heart, heavy as it muft have been, from the precarioufnefs of his fitua- tion, and diilance from his accuftomed haunts, expand- ed at thefe agreeable founds. A converfation eniued ; and the parties, by common confent, adjourned to a ta- vern. Here tlie flranger was kindly welcomed to town; and, after the glafs had circulated for a time, fomethirg was propofed by way of fober amufement — a game at cards, or whatever the Doftor might prefer. The Doftur had been too civilly treated to demur ; but his purle was fcantily furniftied, and it was necefiary to quit his new friends in fearch of a fupply. Mr Murray was the perfon to whom he had recourfe : the reader will not wonder that his interference fhould have fpoiled the adventure. A London {harper, of another denomination, after- wards tried to make advantage by the Doftor. This was an ingenious fpeculator in public medicines. He thought a compofition of the mofl powerful ftimuiants might have a run, under the title of Dr Brono/t's ex- Brown citing pill ; and, for the privilege of his name, offered ' him a lum in hand by no means contemptible, as well as a {hare of the contingent profits. Poor Brown, needy as he was, fpurned at the propofal. After this period, his life affords little variety of in- cident. Like Avicenna, his time fecms to have beea fpent between his literary purluits and his plcalures. A fplendid manner of living, without an income to fup- port it, had become habitual to him : The confequencc was, that, from inability to difcharge certain debts he had contrafted, he was thrown into the king's bench prifon ; from which, however, he was, not long after- wards, releafed by the exertions of a few firm friends, particularly Mr Maddlfon of Charing-crofs, a gentle- man univerfally refpedled for his well-known benevo- lence. As a proof of the attivity he was ftill capable of exerting, it will be fufficient to mention, that he ac- complifhed the tranflation of his Elementa, with the addition of the fupplementary notes, within 23 days, having been informed that a tranllation of the fame waB about to be publiihed by another perlon. Shortly before his death, the ambaffador of the king of Pruffia, in the name of his mailer, made Dr Brown an offer of a fettlement in the court of Berlin; during the negociation of which he was unexpectedly cut off by an apoplexv early in the morning of the ^th of Oilober 1788, the day fucceeding that on which he had delivered to a company of thirteen gentlemen the greater part of the introduClory lecture to his fecoud courfe. At his death, he was between 52 and 53 years of age. His remains were interred in the church-yard of St James's Picadillv ; and the only monument left behind him to tranfmit his name to pofterity is bis own works ; which, when perfonal prejudice no longer ffiall prevail againll their ingenious author, cannot fail to procure him all that delcrved celebrity which they have already, in part, obtained in the different coun- tries of Europe. In 17S7, he publiihed his " Obfervations," without his name, which he afterwards, however, i-efcrs to in the Elements as his own. The " Enquiry," faid to be written by Dr Jones, and which was compofed in as (hort a time as the generality of men would tranfcribc a work of its extent, we can affirm, from undoubted authority, to be his produdlion. This flcetch of the life of the unfortunate Dr Brown would be of very little value if not followed by a view 01 his fyftem ; but to give a complete view of that fyf- tem would far exceed the limits within which, in a work like this, fuch articles muft be confined. We trull, therefore, that our readers will be fatisfied with an abftraft ; and as we are neither the partifans nor op- ponents of the Dofilor, and not vei-y partial to any me- dical fyftem whatever, we (liall content ourfelvcs with inferting, in this place, the view which Dr Beddoes has given of Dr Brown's fundamental propofitious in the valuable obfervatitms which he has prefixed to his edi- tion of the Elements of Medicine. " The varied (Irudlure of organized beings (fays Dr Beddoes), it is the bufinefs of anatomy to explain. Con- fcioufnefs, aflifted by common obfcrvation, will diftin- guifh animated from inanimate bodies with precifion more than fufficient for all the ends of medicine. The caufc of gravitation has been left unexplored by all pru- Qj! dent B R O [ Brovvn. dent philofophers ; and Brown, avoiding all ufelefs dif- » quifition concerning the caufe of vitality, confines liim- felf to the phenomena which this great moving prin- ciple in nature may be obferved to produce. His moft , general propolitions are cafy of comprehenfion. " I. To every aninKited being is allotted a certain portion only of the quality or principle on which the phenomena of life depend. This principle is denomi- nated excilalHity. " 2. The excitability varies in different animals, and in the fame animal at different times. As it is more intenfe, the animal is more vivacious or more fufceptible of the aftion of exciting powers. " 3. Exciting powers may be referred to two claffes. I. External; as heat, food, wine, poifons, contagions, the bluod, fecreted fluids, and air. 2. Internal ; as the funftions of the body itfelf, mufcular exertion, think- ing, emotion, and pafDon. " 4. Life is a forced (late; if the exciting powers are withdrawn, death enfues as certainly as when the excitability is gone. " 5. The excitement maybe too great, too fmall, or in juft meafure. " 6. By too great excitement, weaknefs is induced, becaufe the excitability becomes defeftive ; this is inJi- ■ red debility : when the exciting powers and ftimulants are withheld, weaknefs is induced ; and this is JireH de- bility. Here the excitability is in excefs. " 7. Every power that a£ts on the living frame is ftimulant, or produces excitement by expending excita- bility. Thus, although a perfon accuftomed to ani- mal food may grow weak if he lives upon vegetables, ftill the vegetable diet can only be confidered as pro- ducing an effeft, the fame in kind with animals, though inferior in degree. Whatever powers, therefore, we imagine, and however they vary from fuch as are habi- tually applied to produce due excitement, they can only weaken the fyftem by urging it into too much motion, or fuffering it to fink into langoiir. " 8. Excitability is feated in the medullary portion of the nerves, and in the mufcles. As foon as it is anywhere affefted, it is immediately affefted everywhere ; nor is the excitement ever increafed in a part, while it is gcnei-ally diminifhed in the fyflem ; in other words, diffe- rent parts can never be in oppofite ftates of excitement. " I have already fpoken of an illuitration, drawn up by Mr Chriftie from a familiar operation, to facilitate the conception of Brown's fundamental pofitions. I introduce it here as more likely to anfwer its purpofe than if feparately placed at the end of my preliminary obfervations. ' Suppofe a fire to be made in a grate, filled with a kind of fuel not very combuftible, and which could only be kept burning by means of a ma- chine containing feveral tubes, placed before it, and eonftantly pouring ftreams of air into it. Suppole alfo a pipe to be fixed in the back of the chimney, through which a conftant fupply of frefh fuel was gradually let down into the grate, to repair the wafte occafioned by the flame, kept up by the air machine. ' The grate will reprefent the human frame ; the fuel in it, the matter of life — the excitability of Dr » Brown, and the fenforial power of Dr Darwin ; the tube behind, fupplying frefh fuel, will denote the power of all living fyftems, conftantly to regenerate or repro- duce excitability ; while the air machine, of feveral tubes. 124 1 B R O denotes the various ftimuli applied to the excitability of the body ; and the flame drawn forth in confequence ' of that application reprefents life, the produdt of the exciting powers acting upon the excitability. ' As Dr Brown has defined life to be a forced Jlate, it is fitly rcprcfented by a flame forcibly drawn forth from fuel little difpofed to combullion, by the conftant application of ftreams of air poured into it from the different tubes of a machine. If fome of thefe tubes are fuppofed to convey pure or dephlogifticated air, they will denote the higheft clafs of exciting powers, opium, mufk, camphor, fpirits, wine, tobacco, &c. the diffufible ftimuli of Dr Brown, which bring forth for » time a greater quantity of life than ufual, as the blow- ing in of pure air into a fire will temporarily draw forth an uncommon quantity of flame. If others of the tubes be fuppofed to convey common or atmofpheric air, they will rcprelent the ordinary exciting powers, or ftimuli, applied to the human frame, fuch as heat, light, air, food, drink, &c. while fuch as convey impure and in- flammable air may be ufed to denote what have for- merly been termed fedative powers, fuch as poifons, contagious miafmata, foul air, &c. ' The reader will now probably be at no lofs to un- derftand the feeming paradox of the Brunonlan fyftem ; that food, drink, and all the powers applied to the bo- dy, though they fupport life, yet confume it ; for he will fee that the appJication of thefe powers, though it brings forth life, yet at the fame time it waftes the excitability or matter of life, juft as the air blown into the fire brings forth more flame, but waftes the fuel or matter of fire. ■ This is conformable to the commor\ faying, " the more a fpark is blown, the brighter it burns, and the fooner it is fpent." A Roman poet has given us, without Intending It, an excellent illuilra- tion of the Brunonlan fyftem, when he fays, " Balnea, -vina, Venus, confumunt corpora nojlra; " Sed "vitam faciuni balnea, vina, Venus. " Wine, warmth, and love, our vigour drain ; " Yet wine, warmth, love, our life fuftaln." Or to tranflate it more literally, " Baths, women, wine, exhauft our frame ; " But life itfelf is drawn from them." ' Equally eafy will it be to illuftrate the two kinds of debility, termed dired and indireS, which, according to Brown, are the caufe of all dileafes. If the quan- tity of ftimulus or exciting power Is proportioned to the quantity of excitability, that Is, if no more excite- ment is drawn forth than is equal to the quantity of excitability produced, the human frame will be in a ftate of health, juft as the fire will be in a vigorous ftate when no more air is blown in than Is fufficlent to confume the frefh fupply of iuel conftantly poured down by the tube behind. If a fufBcient quantity of ftimulus is not applied, or air not blown in, the excitability in the man, and the fuel in the fire, will accumulate, pro- ducing diredt debility ; for the man will become weak, and the fire low. Carried to a certain degree, they will occafion death to the firft, and extlnftion to the laft. If, again, an over proportion of ftimulus be applied, or too much air blown in, the excitability will foon be walled, and the matter of fuel almoft ibent. Henc-: %vilJ B R O [ ' Brn\K-n. will arife Indireft debility, producing the fame wraknefs •^-~/~—' ill the man, and lowiiefs in the fire, as before, and equal- ly terminating, when carried to a certain degree, in death and extinftion. ' As all the difeafes of the body, according to Dr Brown, are occafioned by direft or indireft debility, in confeqiience of too much or too little ftimuli, fu all the defefts of the fire muil arife from direft or indirctt low- nefs, in confequence of too much or too little air blown into it. As Brown taught that one debility was never to be cured by another, but both by the more judicious application of ftimuli, fo will be found the cafe in treat- ing the defetls of the fire. If the fire has become low, or the man weak, by the want of the needful quantity of llimulus, more mutt be applied, but very gently at firft, and increafed by degrees, Icil a ftrong ttimuhis ap- plied to the accumulated excitability fhould produce death ; as in the cafe of a limb benumbed with cold (that is, weakened by the accumulation of its excitabi- lity in confequence of the abllraftion ol the ufual lli- mulus of heat), and fuddenly held to the fire, which •we know from experience is in danger of mortification ; or as in the cafe of the fire becoming very low by the ac- cumulation of the matter of fuel, when the feeble flame, aifailed by a fudden and ftrong blaft of air, would be overpowered and put out, inltead of being nouiilhed and increafed. Again, if the man or the fire have been rendered indireftly weak, by the application of too much ftimulus, we are not fuddenly to withdraw the whole, or even a great quantity of the exciting powers or air, for then the weakened life and diminifiied flame might fink entirely ; but we are by little and little to diminilh the overplus of ftimulus, fu as to ei:able the excitability, or matter of fuel, gradually to recover its proper proportion. Thus a man who has injured his conftitution by the abufe of fpirituous liquors is not fuddenly to be reduced to water alone, as is the prac- tice of fome phyficians, but he is to be treated as the judicious Dr Pitcairn of Edinburgh is faid to have treated a Highland chieftian, who applied to him for advice in this fituation. The Doftor gave him no me- dicines, and only exafled a promife of him, that he would every day put in as much wax into the wooden queich, out of which he drank his whiiky, as would re- ceive the imprefiion of his arms. The wax thus gra- dually accumulating, diminifhed daily the quantity of the vvhiflcy, till the whole queich was filled with wax ; and the chieftain was thus gradually, and without injury to his conftitution, cured ot the habit of drinking fpirits. ' Thefe analogies might be purfued farther ; but my objtft is folely to furnifh fome general ideas, to prepare the reader for entering more eafily into the Brunonian theory, which I think he will be enabled to do after perufing what I have faid. The great excellence of that theory, as applied, not only to the praftice of phyfic, but to the general condudt of the health, is, that it im- prefles on the mind a feafe of the impropriety and dan- ger of going from one extreme to another. The hu- man frame is capable of enduring great varieties, if time be given it to accommodate itfelf to different ttates. All the mifchicf is done in the tranfition from one ftate to another. In a ftate of low excitement, we are not r-afhly to induce a ftate of high excitement ; nor when elevated to the latter, are we fuddenly to defcend to the former, but ftep by ftep, and as one who from the top 25 ] B R U of a high tower defcends to the ground. From hafty Bfnwn, and violent changes the human frame always fuffers ; Bruce, its particles are torn afunder, its organs injured, the vi- ''"" tal principle impaired, and difenfe, often death, is the inevitable confequence. ' I have only to add, that though in this illuftratiou of the Brunonian fyftem (written feveral years ago"), I have fpokcn of a tube conftantly pouring in frelh fuel, becaufe I could not otherwife convey to the reader a familiar idea of the power poffeffed by all living fyftems, to renew their excitability when exhaufted ; yet it may be proper to inform the ftudent, that Dr Brown fup- pofed every living fyftem to have received at the begin- ning its determinate portion of excitability ; and, there- fore, although he fpoke of the exhauftion, augmenta- tion, and even renewal of excitability, I do not think it was his intention to induce his pupils to think of it as a kind of fluid fubftance exifting in the animal, and fubjeft to the law by which fuch fubttances are govern- ed. According to him, excitability was an unknown fomeivhat, fubjetl to peculiar laws of its own,.and whofe different ftates we were obliged to defcribe (though inaccurately) by terms borrowed from the qualities of material fubftances.' " The Brunonian fyftem has frequently been char- ged with promoting intemperance. The objedfion is ferious ; but the view already given of its principles fhews it to be groundlefs. No writer had infifted fo much upon the dependence of life on external caufes, or fo ftrongly ftated the inevitable confequenccs of ex- cefs. And there are no means of promoting morality upon which we can rely, except the knowledge of th'i true relations between man and other beings or bodies. For by this knowledge we are diredfly led to Ihun what is hurtful, and purfue what is falutary. And in what eife does moral condud, as far it regards the individual, confift ? It may be faid that the author's life difprov^cs the juftnefs of this reprefentation : his life,, however, only lliews the fuperior power of other caufes, and of bad habits in particular; and I am ready to acknow- ledge the little efficacy of inftruction when bad hsbits are formed. Its great ufe confifts in preventing their formation; for which reafon popular inftruftion in me- dicine would contribute more to the happincfs of the human fpecies, than the complete knowledge cf every thing which is attempted to be taught in education, iw it is condufted at prefent. But though the prii.ciplea of the fyftem in queilion did not correct the prcpenfi- tie? of its inventor, it does not follow that they tend to produce the fame propenfities in others." BRUCE (James, Efq; F. R. S.), the celebrated AbyfTmian traveller, was born, i 730, at Kinnaird houfe, in the parilli of Larbert and county of Stirling. His dcfcent by both parents was ancient and honourable ;' and of that defcent be was, perhaps, too proud. Hij . grandfather was Hay, Efq; of Woodcockdale, i;i the county of Linlithgow, who, marrying Mifs Bruce, the heirefs of Kinnaird, gave the name of Bruce to all his defcendants. Perhaps this change of name may have taken pliee in obedience to the deed bv which the e ftate of ¥Ji\\- naird was fettled on Mrs Hay's children ; but it is a change which, in a country like Scotland, where au' tiquity of defcent is highly valued, any man 'would vo- luntarily have adopted, who had married the heirefs ot" fuch B R U [ 12 Bruce, fucli a faniHy. The- Bruces of KInnaIrd hnd been in — V— 'jjoflcHioii of that cilate for three ceiUuries : tlicy were defceiided from a younger foil of Robert de Bruce, the competitor with Baliul for the crown of Scotland. It would readily occur, that the knowledge of luch a dc- fcent would be bed preferved by continuing the name of their great ancellor ; and we have reafon to believe, that the fubjert of this memoir was not much delighted when put in mind, as he frequently was, that, though the heir of the line, he was not the mak heir of that branch of the illurtiious family. As he was allied to royalty by his father and grand- mother, through his mother he was related to fome of admiralty in Scotland, by Marion, daughter of James Hamilton Efq; of Pencaitland ; and to a man of our traveller's turn of mind, there can be no doubt but that it mu!l have afforded much fatisfaftion to think, that no family ranks higher in Scotland than thofe of Bruce, Graham, and Hamilton. In him, however, it was.weak- nefs to be proud, if indeed he was proud, of family ; for the talents bellowed upon him by nature, or, to fpeak more properly, by nature's God, would have made him great though he had been born on a dunghill. He would indeed have been, in all probability, much greater than he was, had he not been in poffeflion of the phantom of birth to gratify much of his ambition; for the facility with which he mailered every ftudy in which he eno-aged, would have carried him quickly to the top of the moft honourable profeffion. Mr Bruce was inftrufted in grammatical learning at the fchool of Harrow on the Hill, in the county of Middlefex, where he gave the moft unequivocal proofs of g.nius, and acquired a very coniiderable knowledge of the Greek and Latin languages. It was cullomary with him to perform, not only his own exerciles, but alfo the exercifes of fuchof his companions as were not equal to the tallc themfelves. Among thefe was his maternal uncle, who was frequently indebted to his aflillance, and, on one occafion, produced a copy of ver- fes of his compofition, which excited, not only the ap- plaufe, but the admiration of their mailer. Mr Gra- ham, who was but a few months older than Mr Bruce, had, for fome tranfgrcffion (we know not what), been punifhed, as boys in the great fchools in England are often punifhed, by having a ta(l< fet him, whicli he loon found himfelf unable to perform. His nephew delired him to be under no uneafinefs, promiling to furnifli him with the verfes before the time at which they were to be given in. He was as good as his word ; but the mailer of the fchool foon difcovei-ing that they were not the performance of Mr Graham, exclaimed, that the author of thefe verfes, whoever he was, might ap- ply to himfelf the words of Horace, Siibiimi feriam Jidera •vertice. Wliile Mr Bruce was at Harrow, and for a year or two after he had left it, he was of a very delicate frame, and appeared to his friends to be threatened with a confumption. The truth is, that he was un- commonly tall for his age, and felt all the feeblenefs of joints and other bodily weakneflTes to which overgrown boys are generally fubjed. His father intended him 6 ] B R U for the profciTun of the law; and, upon his return Trom Harrow, he was entered into the miiveriity of Edin- burgh, where he went through a regular courfe of ftudy to fit him for being enrolled in the body of advocates : but for fome reaf >n, which we do not perfectly know, he relinquilhcd the ftudy of law for the purfnils of trade; and, going to London, entered into partnerfhip with a wine merchant of the name of Allen, whofe daughter he married. That lady falling into a bad ftate of health, Mr Bruce took her abroad, in hopes that travelling would be at. tended with beneficial effedls ; but in thefe he was dif- appointed, as ftie died within a year after her marriage. He was induced, in order to difpel his grief, to conti- nue his travels ; during which his father dying (at E- diiiburgh, 4th M.iy 1758), the inheritance of his .iiicel- tors devolved upon him, and he returned to Britain. Some of his fubfequent tranfadtions fhall now be rela- ted in his own words. " Every one will remember that period, fo glorious to Britain, the latter end of the miniftry of the late earl of Chatham. I was then returned from a tour through the greateft part of Europe, particularly through the whole of Spain and Portugal, between whom there was then the appearance of an approaching war. " I was about to retire to a fmall patrimony I had received from my anceftors, in order to embrace a life of ftudy and refleftion, nothing more adlive appearing within my power, when chance threw me unexpeftedly into 3 very fhort and very defultory converfation with Lord Chatham. " It was a few days after this that Mr Wood, then under-fecretary of ftate, my zealous and fmcere friend, informed me that Lord Chatham intended to employ me upon a particular fcrvice ; that, however, I might go down for a few weeks to my own country to fettle my affairs, but, by all means, to be ready upon a call. No- thing could be more flattering to me than fuch an ofler, when fo young ; to be thought worthy by Lord Cha- tham of any employment, was doubly a preference. No time was loll on my fide; but juil after receiving orders to return to London, his lordlhip had gone to Bath, and refigned his office. " This dil'appointment, which was the more fcnfible to me that it was the tirft I had met with in public life, was promifed to be made up to me by Lord Egre- mont and Mr George Grenville. The former had been long my friend ; but unhappily he was then far gone in a lethargic indifpofition, which threatened, and did very foon put a period to his exiftence. With Lord Egremont's death my expeftations vanifhed. Further particulars are unnecetTary ; but I hope that, at leaft in part, they remain in that breaft where they naturally ought to be, and where I fliall ever think, not to be long forgotten, is to be rewarded. " Seven or eight months were palFed in an expenfive and fruitlefs attendance in London, when Lord Halifax was pleated, not only to propofe, but to plan for me a journey of confiderable importance, and which was to take up feveral years. His lordfhip faid, that nothing could be more ignoble than, at fuch a time of life, at the height of my reading, health, andadivity, I fhould, as it were, turn peafant, and voluntarily bury myfelf in obfcurity and idlenefs; that though war was now draw- ing fall to an end, full as honourable a competition re- mained Bruo B R U [ Bruce, mainet! jirriong men of fpirit, which Hiould acquit them- '"'V""'' felves beft in the dangerous line ot uictul adventure and difcovery. «' He obferved, that the coaft of Barbary, wlu'ch might be faid to be jult at our door, was yet but par- tially explored by Dr Shaw, who had only illuilrated (very judiciouiiy indeed) the geographical labours of Sanfon; that neither Dr Shaw nor Saiilon had been, or pretended to be, capable of giving the public any de- tail of the large and magnificent remains of ruined ar- chitetlure, which they both vouch to have fcen in great quantities, and of exquiiite elegance and perfeftion, all over the country. Such had not been their Ibidy, yet fuch was really the tafte that was required in the pre- fent times. He wiihtd, therefore, that I (liould be the firll, in the reign jull now beginning, to fct an example of making large additions to the royal collection ; and he pledged himielf to be my fupport and patron, and to make good to me, upon this additional merit, the pro- mifes which had been held forth to me by former mi- niiters for other fervices. ■ " The difcovery of the fource of the Nile was alfo a fubjeft of thefe converfations, but it was always men- tioned to me with a kmd ot diffidence, as if to be ex- pefled from a more experienced traveller. Whether this was but another way of exciting me to the at- tempt I Ihall not fay ; but my heart, in that inllant, did ine juftice to fuggcft, that this too was either to be atchieved by me, or to remain as it had done for thefe laft 2000 years, a defiance to all travellers, and an opprobrium to geography. " Fortune feemed to enter into this fcheme. At the ver)' inllant, Mr Afpinwall, very cruelly and ignonii- nioufly treated by the dey of Algiers, had refigncd his confulfliip, and Mr Ford a merchant, formerly thedey's acquaintance, was named in his place. Mr Ford was appointed, and, dj-ing a few days after, the confuKhip became vacant. Lord Halitax prefled me to accept of this as containing all forts of conveniences for making the propofed expedition. " This favourable event finally determined me. I had all my life applied unweariedly, perhaps with more love than talent, to drawing, the praftice of mathematics, and efpecially that part neceflary to aftronomy. The tranfit of Venus was at hand. It was certainly known that it would be vifible once at Algiers, and there was great reafon to expeft it might be twice. 1 had fur- nidied myfelf with a large apparatus of inftruments, the completell of their kind, for the obfervation. (n the choice of thefe, 1 had been aflilled by my friend Ad- miral Campbell, and Mr Ruffel fecretary to the Turkey Company : every other neceflary had been provided in proportion. It was a pleafure now to know that it was not from a rock or a wood, but from my own houfe at Algiers, I could deliberately take nieafures to place myfelf in the lift of men of fcience of all nations, who were then preparing for the fame fcientific purpofe. " Thus prepared, I fet out for Italy, through France ; and though it was in time of war, and fome ftrong ob- jections had been made to particular paifports, folicited by our government from the French fecretary of ftate, Monfieur de Choifeul moil obligingly waved all fuch exceptions with regard to me, and moft politely affu- red me, in a letter accompanying my pafTport, that thofe difficulties did not in any ihape regard me, but 27 ] B II U that 1 was perfefdy at liberty to pafs throug'i, or re- main in, France with thofe that accompanied me, with-^ out limiting tlieir number, as Ihort or as long a time as ihould be agreeable to mc. " On my arrival at Rome, I received orders to pro- ceed to Naples, there to await his majefty's further commands. Sir Charles Saunders, tlien witli a fleet before Cadiz, liad orders to vifit Malta before he re- turned to England. It was faid tiiat the grand-mailer of that order iiad behaved fo improperly to Mr Har- vey (aftei-wards Lord Brillol) in the beginin'ng of the war, and fo partially and unjuftly between the two na- tions in the courfe of it, that an explanation on our part was btcome neceflary. The grand-mafter no foon- er heard of my arrival at Naples, than, guefling the er- rand, he fent off Chevalier Mazzini to London, where he at once made his peace and his compliments to his majelly u.pon his acccffion to the throne. " Nothing remained now but to take pontlfion of my confullhip. I returned,^ without lofs of time, to Rome, and from thence to Leghorn, where, having em- barked on board the Montreal man of war, I proceeded to Algiers. " While at Naples, I received from (laves, redeemed from the province of Conftantine, accomits of magnifi- cent ruins they had feen while traverfing that country with their mailer the Bey. I faw the abfohite neceffity there was for affiftancc, without which it was impoflible for any one man, however diligent and qualified, to do any thing but bewilder himfelf. All my endeavours, however, had hitherto been unfuccefsful to perfuadeany Italian to put himfelf wilfully into the hands of a peo- ple conftantly looked upon by them in no better light than pirates. At lall Mr I^umifden, by accident, heard ot a young man who was then lludying architcfture at Rome, a native of Bologna, whofe name was Luicri Ba- lugani. I can appeal to Mr Lumifden as to the extent ot this perfon's pradice and knowledge, and that he knew very little when firll fent to me. In the twenty months which he ftaid with me at Algiers, by affiduous application to proper fubjefts under my inllruftion, he became a vei^ confiderable help to me, and was the on- ly one that ever I made ufe of, or that attended me for a moment, or ever touched one reprefentation of archi- teiSure in any part of my journey." Our traveller, when in Spain, liad endeavoured to find accefs to that immenfe collcdlion of Arabic manu- fcripts which were perilliing in the dud of the efcurial; but in vain. " All my fuccefs (fays he) in Europe termi- nated in the acquifition of thofe few printed Arabic books tliat I had found in Holland ; and thefe were rather biographers than general hillorians, and contain- ed little in point of general information. The ftudy of thefe, however, and of Maracci's Koran, had made me a very tolerable Arab; a great field was opening before me in Africa to complete a coUedlion of manufcripts, an opportunity which 1 did not negleft. " After a year fpent at Algiers, conflant converfa- tion with the natives while abroad, and with my manu- fcripts within doors, had qualified me to appear in any part of the continent without the help of an interpreter. Ludolf had afTured his readers, that the knowledge of any oriental language would foon enable them to ac- quire the Ethiopic ; and I needed only the fame num- ber of books to have made my knowledge of that lan- guage Bruce. « R U [ 12 Bruff. giiase go hand in hand with my attainments in the A- ~~v-— ' raljic. My immediate prol'peft of fetting out on my journey to the inland parts of Africa had made me "double my dih'gence ; niree holes ; but Bruce fays exprelsly, that the holes are partly artifi- cial ; and Lobo's defcripiion of them indicates the fame thing. It is therefore not improbable that there may now be four or five holes. B R U [ 130 ] 13 R U Broce. and having now accomplifhed it, he bent his thoughts journey ; the perils attending which lie has related with """^on his return to his native country. "a power of pencil not unworthy of the greatcil mailers. '" He arrived at Gondar on the 19th November 1770 ; All his camels having perilhed, Mr Bruce was under the but found, after repeated foh'citations, that it was by neceffity of abandoning his baggage in the defert, and no means an cafy talk to obtain permiiTion to quit Abyf- with the greateft difficulty reached Aflbuan upon the finia. A civil war in tlie mean time breaking out (no Nile on the 29th of November. uncommon occurrence in that barbarous country), feve- After fome days reft, having procured frelh camels, ral engagements took place between the king's foices he returned into the defert, and recovered his baggage, and the troops of the rebels, particularly three aftions among which is particularly to be remarked a quadrant at a place called Serbraxos on the 19th, 20th, and 23d (of three feet radius) fupplied by Louis XV. from the of May 177 I. In each of them Mr Bruce afted a con- Military Academy at Marfeilles ; by means of which fiderable part; and for his valiant conduct in the fecond noble inftrument, now depofited in the Mufeum at Kin- received, as a reward from the king, a chain of gold, of naird, Mr Bruce was enabled with precifion and accu- 184 links, each link weighing i^t't dwts. or fomewhat racy to fix the relative fituations of the feveral remote more than 2^ lbs. troy in all. At Gondar, after thefe places he vifited. engagements, he again preferred the moil earneft entrea- On the loth of January 1773, after more than four ties to be allowed to return home, entreaties which were years abfence, he arrived at Cairo, where, by his manly • long refilled ; but his health at laft giving way, from and generous behaviour, he fo won the heart of Maho- the anxiety of his mind, the king confented to his de- met Bey, that he obtained a firman, permitting the parture, on condition of his engaging by oath (b) to commanders of Englifh veflels belonging to Bombay return to him in the event of his recovery, with as ma- and Bengal to bring their fhips and merchandife to- ny of his kindred as he coyld engage to accompany Suez, a place far preferable in all refpefts to Jidda, to },j[n_ which they were formerly confined. Ot this permif- After a rcfidence of nearly two years in that wretch- fion, which no European nation could ever before ac- ed country, Mr Bruce left Gondar on the 1 6th of De- quire, many Englilh velTels have fince availed them- cember 1771, taking the dangerous way of the defert felves ; and it has proved peculiarly ufeful both in pub- of Nubia, in place of the more eafy road of Mafuah, lie and private difpatches. Such was the worthy con- by which he entered Abyffinia. He was induced to clufion of his memorable journey through the defert; a take this route from his knowledge and former expe- journey which, after many hardfhips and dangers, ter- rience of the cruel and favage temper of the Naybe of minated in obtaining this great national benefit. Mafuah. Arriving at Teawa the 21ft March 1772, he At Cairo Mr Bruce's earthly career had nearly been had the misfortune to find the Shekh Fidele of Atbara, concluded by a diforder in his leg, occafioned by a the counterpart of the Naybe of Mafuah in every bad worm in the fielh. This accident kept him five weeks quality : by his intrepidity and prudence, however, and in extreme agony; and his health was not re-eftablilhed by making good ufe of bis foreknowledge of an eclipfe till a twelvemonth afterwards, at the baths of Porretta of the moon, which happened on the 17th of April, he in Italy. On his return to Europe, Mr Bruce was re- was permitted to depart next day, and he arrived at ceived with all the admiration due to fo exalted a cha- Sennaar on the 29th of the fame month. rafter. After pafiing fome confiderable time in France, Mr Bruce was detained upwards of four months at particularly at Montbard, with his friend the Comte de that miferable and inhofpitable place ; the inhabitants of BufFon, by whom he was received with much hofpita- which he defcribes in thefe expreffive words : " War lity, and is mentioned with great applaufe, he at laft rc- and treafon feem to be the only employment of thefe vifited his native country, from which he had been up- horrid people, whom heaven has feparated by almoft wards of twelve years abfent. impaffable deferts from the reft of mankind, confining It was now expefted that he would take the earlieft them to an accurfed fpot, feemingly to give them an opportunity of giving to the world a narrative of his earneft in time of the only other worfe which he has travels, in which the public curiofity could not but be leferved to them for an eternal hereafter." This delay deeply interefted. But feveral circumftances contribu- was occafioned by the viUany of thofe who had under- ted to delay the publication ; and what thefe were will taken to fupply him v^ith money ; but at laft, by dif- be beft related in his own words : pofing of 178 links of his gold chain, the well-earned " My friends at home gave me up for dead ; and as trophy of Serbraxos, he was enabled to make prepara- my death muft have happened in circumftances difficult tion for his dangerous journey through the deferts of to have been proved, my property became as it were a J^ubia. hicreditas jacens, without an owner, abandoned in com- He left Sennaar on the 5th of September, and ar- mon to thofe whofe original title extended no further rived on the 3d of Oftober at Chendi, which he quit- than temporary poffeffion. ted on the 20th, and travelled through the defert of " A number of law-fuits were the inevitable confe- Gooz, to which village he came on the 26th of Odlo- quences of this upon my return. To thefe difagreeable ber. On the 9th of November he left Gooz, and en- avocations, which took up much time, were added others tered upon the moft dreadful and dangerous part of his ftill more unfortunate. The relentlefs ague, caught at Bengazi, (b) With regard to this oath, Mr Bruce fays, that he hopes the difficulty of performing it extinguifited the fin of breaking it ; and that, at any rate, it being merely perfonal, his engagement to return ceafed with the death of the king, of which he received intelligence during his ftay at Sennaar, B R U [13 uce. Bengazi, maintained its ground, at times, for a fpace of V ■ more than 16 years, though every remedy had been nfed, hut in vain ; and what was word uf all, a h'nger- ing dilleinper had ferloufly threatened the h'fe of a mod near relation (his fecond wife), which, after nine years conftant alarm, where every duty bound me to attention end attendance, condudled her at lad, in very early life, to her grave." Amidft the anxiety and the diftrefs thus occafioned, Mr Bruce was by no means negleftful of his private af- fairs. He confiderably improved his landed property, enclofing and cultivating the wafte grounds, and he high- ly embellilhed his paternal feat, making many additions to the houfe, one in particular of a noble mufeum, filled with the moll precious (lores of oriental literature, large coUeftions of drawings made, and curious articles ob- tained, during his far extended peregrinations. An ex- cellent ftratum of coal at Kinnaird drew much of his at- tention : he erefted fteam engines of the moll approved conftruftion, and placed his coalery on fuch a footing that, at the period of his deceafe, it produced about aoool. a-year. The termination of fome law-fuits, and of other bufi- nefs, which had occupied much of his time, having at length afforded leifure to Mr Bruce to put his mate- rials in order, his greatly defired and long expedled work made its appearance in 1790, in five large quarto volumes, embellilhed with plates and charts. It is un- receffary, and might be tedious, to enter at prefent in- to any critic or analyfis of this celebrated work. It is vuiiverfally allowed to be replete with much curious and ufeful information ; and to abound in narratives which at once excite our admiration and intereft our feelings. The very Angular and extraordinary pifture which it gives of Abyflinian manners, ftartled the belief of fome; but thefe manners, though ftrange in the fight of an European, are little more than might be expedled in fuch a barbarous country ; and had an enlightened phi- lofopher vifited Scotland in the times of our earlieft mo- narchs, he might perhaps have witnefled and related fcenes, different indeed from what Mr Bruce faw in AbyfTmia, but which to us would have feemed equally ftrange. A more ferious objeftion to the truth of Mr Bruce's narrative was darted by an anonymous, but able, cri- tic *, in an Edinburgh newfpaper, foon after the pub- *^"PP° lication, from the account of two adronomical phe- 'lotheram nomena, which could not pojjibly have happened, as Mr l.rofeflbr of Bruce afferts. The firll of thefe is the appearance of i»turalpM-tln; new moon at Furfhout, during Mr Bruce's day in oiophy in ^^.^^ place, which he mentions to have been from 25th iity of St December 1768 to the 7th of January 1769 ; and on a Andrew's, particular day in that interval aflTcrts, that the new moon was feen by a fakir, and was found by the ephemerides to be three days old ; whereas it is certain that the moon changed on the 8th of January 1769. The other phenomenon appears equally impollible. At Teawa Mr Bruce fays he terrified the Shekh by foi-etelling that an eclipfc of the moon was to take place at four afternoon of the 17th of April 1772 i that accordingly, foon after that hour, he faw the eclipfe was begun ; and when the fhadow was half over, told the Shekh that in a little time the moon would be totally darkened. Now-, by calculation, it is certain that at Teawa this eclipfe mud have begun at 36 minutes pad four, and the mooa I j B R U have been totally covered at 33 minutes pad five; while Brucp the fun fet there a few minutes pad fix, before which """V"" time the moon, then in oppofition, could not have ri- fen : fo that as the moon rofe totally eclipfed, Mr Bruce could not fee the diadow half over the diflc, nor point it out to the Shekh. To thefe objeftions, which ap- pear unfurmountable, Mr Bruce made no reply, though in converfation he faid he would do it in the fecond edi- tion of his book. Thefe are midakes which can hardly be accounted for by attributing them to the inaccuracy of his notes, or indeed to any caufe which we are inclined to name ; and perhaps he has fallen into a miflake of the fame kind in his account of the enormous main-fail yard of the canja, in which he failed up the river Nile. To every man who has but dipped into the fcience of me- chanics, it is known that a beam of wood ,00 feet in • length, mud be of proportional thicknefs, or it would fall in pieces by its own weight. This thicknefs mud be greatly increafcd, to enable it to bear the drain oc- cafioned by a prodigious fail filled with wind; and thofe only who have been at the Nile, and have feen the can- jas, can fay, whether thefe veffels, or indeed any vef- fels which can be employed on that river, would not be overfet by yards, To equal which, the tailed pine Hewn on Norwegian hills, to be the mad Of fome great admiral, were but a wand. The language of the work is in general harfli and un- polifhed, though fometimes animated. Too great a dilplay of vanity runs through the whole, and the ap- parent facility with which the traveller gained the mod familiar accefs to the courts, and even to the harams of the fovereignsof the countries through which he palftd, is apt to create in readers fome doubts of the accuracy of the narration. Yet there appears upon the whole fuch an air of manly veracity, and circumilances are mentioned with a minutenefs fo unlike deceit, that thefe doubts are overcome by the general impreffion of truth, which the whole detail irrefidibly fadens upon the mind. The charadler of Ras Michael has often ftruck us, as containing very drong internal evidence of its having been taken from nature ; for it is fuch a charafter, at once extraordinary and confident, as neither Mr Bruce, nor perhaps any writer fince Shakefpeare, had genius to feign. The fird impveflion of the book being almoft difpo- fed of, Mr Bruce had ftipulated with an eminent book- feller in London for a fecond edition to be publifhed, we think in odlavo ; and he was bufy in preparing that edition for the prefs when death removed him from this tranfitoiy dage. On the 26th of April 1794 he entertained fome company at Kinnaird-houfe with his ufual hofpitality and elegance. About eight o'clock in the eveninpr, when his guefis were ready to depart, be was handing one of the ladies down flairs, when, having reached the feventh or eighth flep from the bottom, his foot flipped, and he fell down headlong. He was taken up fpeechlefs ; his face, particularly the forehead and temples, being feverely cut and bruifed, and the bones of his hands broken. He continued in a date of appa- rent infenfibility for eight or nine hours, and expired on Sunday the 27th, in the 64th year of his age. Mr Bruce's fecond wife, whom he married on the R 2 icth B R U> [ 132 ] BUG Bnicc. 20tK May 1776, was Mary, eldell daughter of Tho. TarfliJfli had been controverted by Dr Dofg of Stirling, * ' mas Dundas, Efq; of Carron-ball, by I.ady Janet Malt- he earneftly courted the acquaintance of that eminent land, daughter of Charles fixth Earl of Lauderdale. By that lady, who, after a fcvcre and lingering indilpoli- xmci u.s ^ ...^ v,„,, ^w..,.,.. j, .^v .....utu luun- tion died in 1784, he bad three children, of whom one ly at Kinnaird ; and till he became corpulent, fpent fon Lnd one daughter furvivc him. much of his time in the various fporta of the field, in Mr Cruce's pcrfon was large, his height exceeding which he engaged with great ardour. Though ttudious fix feet, his bulk, being in proportion to his height j in youth, and at all times a ftranger to intemperance and at the period when he entered on his dangerous ex- and diffipation, he read but little in his later years; and pedition, he was equally remarkable for ftrength and feemed to find his cliief pleafure in converfation, efpe- for agility. To thofe who never beheld him, the en- cially the converfation of well-informed ladies. In his i.ravcd medallion in the title pages of the firft and third friendlhips he fometimes appeared to be capricious, at- vo'lumes of his Travels will convey fome idea of his fea- taching himfelf to men in whofe heads and hearts no tures. He excelled in all manly aecompliftments, being other perfon could perceive a charm for a mind lik'e his. trained to exercife and fatigue of every kind. He was Though in his own deahngs he was always juft and ho- a hardy, pradifed, and indefatigable fwimmer ; and his nourable, he was too ready to apprehend unfairnefs in long residence among the Arabs had given him a more others, and to exprefs fuch apprehenfions with undue than ordinary facility in managing the horfe. In the ufe warmth. To ftrangers he was often arrogant, and of fire-arms lie was fo unerring, that in innumerable in- fometimes infolent ; but in his own family he was an fiances he never failed to hit the mark ; and his dexte- affeaionate hufband, a kind father, an agreeable enter- rity in handling the' fpear and lance on horfeback was tainer, and to his fervants a mailer perhaps too indul- alfo uncommonly great. He was niafter of moft Ian- gent. In converfation, as well as in his writings, he ges ; and was fo well (lny, there is a fmall flream, which runs into E- Jewfis Bay, near the new fettlement called Hefper ma no animals have been difcovered, the wolf, fome buf- faloes, a tew elephants, and a fpecies of the deer, ex- cepted. " The woods abound with doves, guinea-fowls, and a variety of birds, celebrated for the beauty of their plumage. " The natives of this part of Africa, like all favages, are entirely under tire dominion.of their paffions : hence the violence of their attachment to their friends, and the excefs of their refentment againil their enemies. Their notions of property are very obfcure and confu- fed : they have no idea of any right arifmg from occu- pancy or improvement. What they want, they either receive or take wherever they may happen to meet with Elewfis : this is admirably fituated for the fiipply of it, and they permit others to do the fame. They have (liipping. been taught by experience that the Europeans will not " The ifland is beautifully furrounded, and interfper- agree to this : againft them therefore they employ- fed with woods ; lofty fruit and foreft trees, moftly free every artifice that it is in the power of cunning to fug- from underwood and brambles, form a verdant belt, in geft. fome places two or three miles broad, which entirely encircles it, in fuch a manner as to reprefent a planta- tion artificiaUy formed around a park. Within this the fields are regularly divided by trees, fo as to refem- ble the hedge-rows in England. The beach has in foine places the appearance of gravel walks ; it is fringed with mangrove trees, which forming a line with the high-water mark, dip their branches into the fea, and thus afford nourifhment to the oyflers that often adhere to their extremities. " The colonifts need not fear any attack on the part of the negroes, provided their own conduft be juft and peaceable : for Mr Beaver, who was indeed admirably calculated by nature and habit for the flation he occu- pied, could enfure both fafety and refpeft when the fet- tlers under him were reduced to four white men, al- though the neighbouring nations knew that he was In pofTeffion of commodities, for the acquliition of which many of them had become day-labourers. He often kept from twenty to forty gromlttos, or black cultlva- " Several parts of Bulama have been occafionally cul- tors In pay, at that very period, at about four or five tlvated by the neighbotiring blacks, though they did ba^rs (a) each per month. Thefe are eafy to be procu- not conftantly refide on it. red, to almoft any number that can poffibly be wanted. " The land in general rifes gradually towards the " Until a fufficient quantity of flock and provifions middle of the ifland, where the hlgheft fpot is from 60 can be raifed in the company's fettlements, the adjacent ,to 100 feet above the level of the fea. The fmall hill Iflands will funilfli abundance of cattle, hogs, fowls, &c. on which the fort is fituated is nearly of the fame alti- at a very cheap rate. A horfe may be purchafed at tude. Goree for il. ics. a bullock may be had from 12s. to " The foil is abundantly rich and deep ; ftones do 18 s. ilerllng : provifions of all kinds are equally reafon. not here impede the labours of the farmer; and indeed able. Honey is alfo to be procured in great plenty, none have hitherto been difcovered, but a fmall fort, and bees-wax may be rendered an advantageous objeft refembllng pieces of ore, which are to be met with on of commercial fpeculatlon. the fliore. There are many fa-vunnahs or natural mea- " In fhort, the acquifition of Bulama, Areas, and dows, fo extenfive that the eye can fcarcely defcry their the adjacent territories, prefents the faireft opportunity boundaries. Thefe are admirably adapted for the rear- of furnifliing Europe with many valuable articles that ing of flock and feeding of cattle of every kind. have hitherto been brought from more remote coun- " Cotton, indigo, rice, and coffee, grow fpontane- tries, with much greater hazard, and at an increafed oufly on this coafl ; the fugar-cane is Indigenous to expence. The Intercourfe with England Is eafy, fafe, many parts of Africa, and might be cultivated here by and expeditious ; for the voyage may be performed in the labour of freemen, in equal perfeftion, and to much the fpace of three or four weeks : and by the terms of greater advantage, than In the exhaufled iflands of the the hrd fubfcrlptlon, a fettler on Bulama might pur- Weft Indies. All kinds of tropical produftlons, fuch as pine-apples, limes, oranges, grapes, plums, caffada, guava, Indian wheat, the papaw, water-melon, mufk- nielon, the pumpkin, tamarind, banana, and numbers of other delicious fruits, alfo flourlfli here. The adjoin- ing territories produce many valuable forts of fpices, chafe 5C0 acres of land for L. 30 Sterling ; by the terms of the fecond, which we fuppofe are the terms at pre- fent, he might purchafe on the Iflands of Bulama and Areas, or on that part of the adjacent coaft which was ceded to the fociety by the kings of Ghinala, ioo acre* for L. 50 ilerllng. " The (a) a bar is about the value of three fhillings and fixpence. BUN [ I « The colonization of Africa opens a noble and ex- ^ tenfive field to nations and to individuals. To people tbofe fertile territories, defpoiled of their inhabitants by the (lave-trade ; to rear the produdions of the climes between the tropics, by the afiiftance of free men ; to give ample fcope to the induftry and exertions of thofe who may be inclined to remove from Great Britain ; and to extend the commerce and the manufaftures of our native country — thefe are fubjefts which have ex- cited the attention of the Bulama affociation, and now claim the affillance of the ingenious, the fupport of the rich, and the concurrence and good wirties of all." BUNTING, is a bird which has been defcribcd un- der its generic name Emberiza {Encycl.) ; but there is one fpecies, the orange Jljouldered bunting of Latham, of which M. Vaillant relates fome particulars certainly not unworthy of notice in this place, " The female of this beautiful bird (fays he) has the fimple colours of the flcy-lark, and a fliort horizontal tail, likt that of almoft all other birds : the male, on the contrary, is wholly black except at the flioulder of the wing, where there is a large red patch ; and his tail is long, ample, and vertical, like that of the common cock. But this brilliant plumage and fine vertical tail fublift only during the feafon of love, which continues fix months. This period over, he lays aiide his fplendid habiliments, and aflumes the more modeft drefs of his mate. The moft extraordinary circumftance is, that the vertical tail alfo changes to a horizontal one, and the male fo exadlly refembles the female, that it is not pof- fible to diftinguifh them from each other. " The female has her turn. When flie reaches a cer- tain age, and has loft the faculty of propagating the fpecies, (he clothes herfelf for the remainder of her days in the garb which the male had temporarily afTumed ; her tail, hke his at that period, grows long, and, like his alfo, from horizontal becomes vertical. " The birds of this fpecies affociate together, live in a fort of republic, and build their nefts near to each other. The fociety ufually confifts of about fourfcore females ; but, whether by a particular law of nature, more females are produced than males, or for any other reafon of which I am ignorant, there are never more than twelve or fifteen males to this number of females, who have them in common." According to our author, this tranfmutation is by no means confined to this parti'cular fpecies of bunting. Many females of the feathered creation, when they grow fo old as to ceafe laying eggs, affume the more fplendid colours of the male, which they retain during the remainder of their lives. This faft is ilrikingly per- dcptible in thofe fpecies in which the male and female very much differ in colour, as the golden pheafant of China, for inftance. In fome fpecies, and thofe not a few, the male alone regularly changes his colour, and affumes once in a year the plumage of the female ; fo that at a certain period all the birds of that fpecies ap- pear females. " I have in my poflelTion (fays our au- thor) fpecimens of more than fifty of thofe changing fpecies, in all their tranfitions from one hue to another ; and the change is fometimes fo great, that a perfon ■would fuppofe himfelf to fee individuals totally diffe- rent. A clofet-naturalift, for inftance, fhewed me four birds as fo many different fpecies, and even as not be- longing to the fame genus, with, which I was well ac- 35 .] BUR qiiainted, and which I knew to be the fame bird, only Burke of different ages." ' /— Such changes as thefe, could they be proved to take place occafionally among domcftic fowls, would in fome meafure account for ftrange ftories of cocks laying eggs, which we have heard related by perfons whole general veracity was never qucftioned. BURKE (Edmund), was born in the city of Dub- lin on the ift of January 17.^0. His father was an at- torney of confiderable knowledge in his profcflion, and of extenfivc pradlice ; and the family from which he fprung was ancient and honourable. He received the rudiments of his claffical education under Abraham Shackleton, a Quaker, who kept :i private fchool or academy, as it has been called, at Bellytore, near Car- low, and is faid to have been a very fliilful and fuccefs- ful teacher. Under the tuition of this mafter, Burke devoted him- fclf with great ardour, induftry, and perfeverance, to his ftudies ; and manifefted, even from his boyilli days, a diftmguilhed fuperiority over his contemporaries. He was the pride of his preceptor, who prognofticated eve- ry thing great from his genius, and who was, in return, treated by his illuftrious pupil, for forty years, with re- fpeft and gratitude. From fchool Burke was fent to Trinity-college, Dub- lin, where it was afl"erted by Goldfmith and others his contemporaries, that he difplayed no particular eminence in the performance of his exercifes. Like Swift, he defpifed the logic of the fchools ; and like him too, he devoted his time and his talents to more ufeful purfuits. Johnfon, though proud of being an Oxonian, did not much employ himfelf in academical exercifes ; and Dry- den and Milton, who ftudied at Cambridge, were nei- ther of them ambitious of college diliinftions. Let not, however, the example of a Burke, a Johnfon, a Dryden, or a Milton, feduce into by-paths the ordina- ry ftudent ; for though great genius either finds or makes its own way, common minds iiiuft be content to purfue the beaten track. Shakcfpeare, with very little learning, was the greateft dramatic poet that ever wrote ; but how abfurd would it be to infer from this fatl,'that every illiterate man may excel in dramatic poetry ? _ Whilil at college Burke applied himfelf with fuffi- sient diligence to thofe branches of mathematical and phyfical fcience which are moft fubfervient to the purpo- fes of life; and though he neglefted the fyllogiltic lo- gic of Ariftotle, he cultivated the method of induftion pointed out by Bacon. Pneuniatology, likcvvife, and ethics, occupied a confiderable portion of his attention ; and whilft attending to the acciuifition of knowledge, he did not negleft the means of communicatina- it. He ftudied rhetoric and the art of compoiition, as well ai logic, phyfics, hiftory, and moral philofophy ; and had at an early period of his life, fays Dr Bidet, planned a confutation of the metapliyfical theories of Berkeley and Hume. For fuch a taflc as this, we do not think that nature intended him. Through the evcr-attive mind of Burki.' ideas feem to have flowed with too great rapiditv to permit him to give that patient attention to minute di- itinftions, without which it is vain to attempt a confu- tation of the fubtleties of Berkeley and Hume. The ableft antagonift of thefe two pliilofophers was remark- able for patient thinking, and even ap^ar^irt fiownefs of apprebjnfiou 3 1^6 BUR [ TnirVc. apprehenfion ; and we have not a doubt, but that if he - » had pofftfil'd the rapidity of thought which chara6te- rifed Burke, hi> confutation of Hume and Berkeley wo -Id have bet-n far from conclufive. It might have bctn equal to the Ef.y on the Nature and Immutability of Trir.h, but wonld not have been what we find it m "The It quiry into the Human Mind en the Principles of Common S^nfe, and in The EJfays on the Intel/eSual and ^ili-ue Porufrs of Man. A taflc much better fuited to Burke's talents than the writing of metaphyfical difquifitions on the fubllra- tum of body, prefented itfelf to him in the year 1749, and 3 tan< \vhicb was likcwife more immediately uleful. At that period one Lucas, a democratic apothecary, wrote a number of very daring papers againll govern- ment, and acquired by them as great popularity at Dub- lin as Mr Wilkes afterwards obtained by his North Briton in London. Burke, though a boy, perceived, almoil intuitively, the pernicious tendency of fuch le- veri:ig doftrines, and refolved to counteraft it. He wruu- feveral effays in the ftyle of Lucas, imitating it fo ey.idfly as to deceive the public ; purfuing his prin- cip'tf to confequences necefTarily refulting from them, and Ihcwing at the fame time their abfurdity and their dai-^er. Thus was his firft literary effort, like his laft, calculated to guard his country againft anarchical inno- vations. Whilft employed in treafuring up knowledge, which at a future period was to command the admu-ation of liftening fenates, he did not negledl the means iiecelfary to render himfelf agreeable in the varied intercourfe of private life. To the learning of a fcholar he added the manners of a gentleman. His company was fought among the gay and the fafhionable, for his pleafing con- verfation and eafy deportment ; as much as among the learned, for the force and brilliancy of his genius, and the extent and depth of his knowledge. But though ' the objeft of very general regard in his native country, lie had hardly any profpeA of obtaining in it an inde- pendent fettlement. He therefore applied, fome time aftei' the publication of his letters expofing the do&rlnes of Lucas, for the profeflbrlhip of logic, which had then become vacant in the univerfity of Glafgow : but whe- ther th^t application vias made too late, or that the uni- verfity was unwilhng to receive a (Iranger, certain it is that the vacant chair was filled by another, and that Burke was difappointed of an office in which he was eminently qualified to excel. For many years very little attention has been paid in tlie univerfities of Scotland, perhaps even too little, to the Ariftotellan logic ; and the profeffors, inftead of employing their time in the analyfing of fyllogifms, deliver leftures on rhetoric and the principles of compofition — leisures which no man was more capable of giving than the unfuccefsful can- didate for the profelforlliip in Glafgow. Difappointment ot early views has frequently been the means of future advancement. Had Johnfon be- come matter of the Stafford (hire fchool, talents might have been confumed in the tuition of boys which Pro- vidence formed for the inftrndlion of men ; and had Burke obtained the profeflToi fhip of logic in Glafgow, he would have been the moft eloquent lefturer in that univerfity, inftead of the moft brilliant fpeaker in the Britilh fenate : but whether his talents might not have been as ufefully employed in the univerfity as in the it. ] BUR nate, may perhaps be a queftion, though there can be no Burke, queftion whether they would have invefted himfelf with ~~~v~~ an equal blaze of fplendour. Difappointed in Glafgow, he went to London, where he immediately entered himfelf of the Temple ; and as there is reaiou to believe that he was in ftraitened cir- cumftances, he fubmitted to the drudgery of regularly writing for daily, weekly, and monthly publications, elfays on general literature and particalar politics. The profits ariling from fuch writings were at firft fmall ; but they were fo necelfary to their author, that the in- tenfe application which they required gradually impair, ed his health, till at laft a dangerous illnefs enfued, when he reforted for medical advice to Dr Nugent, a phyfician whofe (Icill in his profeffion was equalled only by the benevolence of his heart. The Doftor, confider- ing that the noife, and various difturbances incidental to chambers, muft retard the recovery of his patient, fur- nlflied him with apartments in his own houfe, where the attention of every member of the family contribu- ted more than medicines to the reftoration of his health. It was during this period that the amiable manners of Mifs Nugent, the Doftor's daughter, made a deep im. prefTion on the heart of Burke ; and as fhe could not be infenfible to fuch merit as his, they felt for each other a mutual attachment, and were married foon aftef his recovery. Hitherto his mental powers and acquirements were known in their full extent only to his friends and more intimate companions ; but they were now made public in his firft acknowledged work, intitled, A Vindication of Natural Society. The objeft of this performance was to expofe the dangerous tendency of Lord Bolingbroke's philofophy. By the admirers of that nobleman, his principles were deemed inimical only to revealed reli- gion and national churches, which they would have been glad to fee overturned, provided our civil eftablifh- ment had been preferved; and to the civil eftabliftment they perceived no danger in the writings of the author of The Patriot King. Mr Burke thought very diffe- rently ; and endeavoured to convince them, that if his Liordihip's philofophy fiiould become general, it would ultimately dettroy their rank, their confequence, and their property, and involve the church and ftate in one common ruin. In his ironical attack upon artificial fociety, he makes ufe of the fame common place mode of unfair reafoning which his noble antagonift had em- ployed againft religion and religious eftablifliments. He argues, from the incidental abufes of political fociety, that political fociety muft itfelf be evil ; he goes over every form of civil polity, pointing out its defefls in the moft forcible language; and, in perfeft imitation of the fceptical philofophy, he pulls them all down, one after another, without propofing any thing in their ftead. So complete is the irony, that to many not ac- quainted with fuch difquifitions, he would appear to be ferioufly inveighing againft civil government ; and we have aiifually heard fome of the advocates for modern innovation mention this work as a proof how different Mr Burke's opinions In politics once were from what they appear to have been when he wrote his Refe3ions on the French Re-volution. The truth, however, is, that there is no inconfiftency between The Vindication of Natural Society and the la- teft ptiblications of its illuftrious author. At the pe- riod BUR r I rioJ when that work, was publiHied, infidelity had in- ' fefted only tlie higher orders of men, and fuch of the lower as had got the rudiments of a liberal edncatioii. Of thefe we believe a finglc individual was not then to be found, who fuppofed that fociety could fubhll both without government and without religion ; and there- fore while they laboured to overturn the church, and to prove that Chrillianity itfelf is an Impollure, they all pretended to be zealoufly attached to our civil go- vernment as eftabliflied in king, lords, and commons. Except the clergy of the eftabliflied church, there was no order of men whom they indifcriminately reviled. Hence it was that not Burke only, but Warburton, and almoft every other opponent of Lord Bolingbroke, b«gan their defences of revelation, by (hewing the in- dlflbluble connexion between our civil and ecclefiaftical eftabllfhments ; and all the difference was, that he did, through the medium of the moft refined irony, the very fame thing which they had done by ferious reafoning. Soon after his Vindication of Natural Society, Burke publllhed jl Philofophical Enquiry into the Origin of our Ideas of the Sublime and Beautiful ; a work which foon made its author univerfally known and admired, and which has been ftudied by every Englifli reader ot tafte. It is therefore needlefs for us to hazard any opinion either of Its general merit or Its particular defefts. In one of the literary journals of that day, Mr Murphy urged objeftlons agalnft fome of its fundamental prin- ciples, which, in our opinion. It would be very difficult to anfwer ; whilft Johnfon, who was certainly a fevere judge, confidered it as a model of philofophical criti- clfm. " We have (faid he) an example of true crltl- cifm in Burke's Efiay on the Sublime and Beautiful. There is no great merit in (hewing how many plays have giiofts in them, or how this gholt Is better than that ; you mult (hew how terror is Imprefl'ed on the mind." In confequence of this manifeflation of Burke's In- telleftual powers, his acquaintance was courted by men of diftinguifhed talents, and, among others, by Johnfon and Sir Jofliua Reynolds. The literary club which has been mentioned [Encycl.) in the life of Johnson, was inftituted for their entertainment and inflruftion, and confifted at firff: of Johnfon, Burke, Reynolds, Gold- fmith, Dr Nugent, Mr Topham, Beauclerk, Sir John Hawkins, Mr Chamler, and Mr Bennet Langton, who were all men of letters and general information, though far above the reft ftood Burke and Johnfon. Of Burke indeed Johnfon declared, upon all occafions, that he was the greateft man living; whilft Burke, on a very folemn occafion, faid of Johnfon, " He has made a chafra, which not only nothing can fill fip, but winch nothing has a tendency to fill up. Johnfon is dead. Let us go to the next beft — There is nobody — No man can be iaid to put you in mind of Johnfon." Nor was the opinion which thefe two illultrious men held of each other's powers peculiar to themfelves alone : all the members of the club obferved, that in colloquial talents they were nearly matched, and that Johnion never dlf- courfed with fuch animation and energy as when his powers were called forth by thofe of Burke. Some years before the inftitution of this club, Burke, who had devoted much of his time to the iludy of hl- ftory and politics, propofed to Mr Dodfley, an eminent bookfeller, a plan of an Annual RfiGiSTER.of the ci- SuppL. Vol. I. Part I. 37 1 B IT R vil, political, and literary tranfiCtious of the times ; and the propolal being acceded to, the work was begun and ■■ carried on for many years, cither by Burke himftlf, or under his immediate infpeftioji. It bears indtcd inter- nal marks of his genius, his learning, and his candour, being by much the moft elegant and impartial periodi- cal hiftory which has perhaps appeared in any age or nation. Even when the heat of oppolition made him, in his fpeeches, fometimes mifrcprelent the conduft ot admlniftration, the Annual Regifter, under his manage- ment, continued to render juftice to all parties. He ftill continued to write occafionally political eC fays for other publications than the Annual Regifter ; and fome of thefe eflays in the Public ,-l dvertifer having attrafted the notice of the Marquis of Rockingham, that nobleman fought the acquaintance of their author. It was In the year 1765 that the firft interview took place between them ; and the Marquis, who was then at the head of the treafury, off"erIng to make Burke his own fecretary, the offer was readily accepted. On this occafion he gave a remarkable pcoof of difintereftednefs and delicate Integrity. Through the influence of Mr Hamilton, known by the appellation of Single Speech Hamilton, and long fufpe6ted to be the author of Ju- nius's Letters, he had fome time before obtained a pen- fion of L.300 a-year on the Irifti eftablKhment ; but this penfion he now thought it incumbent upon him to refign, becaufe he had connefted himfelf with a party oppofite In many things to the party whofe meafures were fupported by his friend. During the Rockingham admlniftration he was cho- fen member of Parliament for tlie borough of Wendover in the county of Bucks ; and he prepared himfelf for becoming a public fpeaker, by ftudying, ftUl more clofe- ly than he had yet done, hiftory, poetry, and philofo- phy ; and by ftoring his mind with fafts, Images, rea- fonlngs, and fentlments. He paid great attention like- wite to parliamentary ufage ; and was at much pains to become acquainted with old records, patents, and pre- cedents, fo as to render himfelf complete mailer of the bufinefs of office. That he might communicate with- out embarraflrnent the knowledge which he had thus laborioudy acquired, he frequented, with many other men of eminence, the Robin Hood Society, where he praftifed the replies and contentions of eloquence ; and to acquire a graceful adflon, with the proper manao-e- ment of his voice, he was a very diligent obfcrver of Ganick in Drury-Lane theatre. He procured his feat In 1765, and in the enfuing fefliou delivered his maiden fpeech ; which was fuch a difplay of eloquence as ex- cited the admiration of the Houfe, and drew very high praife from Its moft diftingulflied member Mr Pitt, af- terwards Earl of Chatham. The principal objefts which engaged the attention of the Rockingham admlniftration were f,he ferments In America, which was then in a ftate little (liort of re- bellion, on account of the famous ftamp-adl. Parlia- ment was divided In oplin'on refpefting that mcafure. Whilft Mr Grenville and his party (under whofe au- fpices the ftamp-aft had paiTed into a law) were for enforcing obedience to it by coercive meafures, Mr Pitt and his followers denied that the piulianunt of Great Britain had a right to tax the Americans; and the mar- quis of Rockingham, who was hardly able to carry any meafure in oppolition to both thefe parties, had to cou- S fidtr, Buike BUR [ I Barhe. fijer, on this occafion, vvhofe fentiments h; would a- ""^V"^ dopt. By the advice, it is faid, of Mr Burke, he chofe a middle courfe between the two oppofite extremes. To gratify the Americans, he repealed the llamp-ad ; and to vindicate the honour of Britain, he got a law paffed declaratoiy of her ri^ht to legiflate for America in taxation as in every other cafe. This mcafure, whoever was its au'.hor, was certainly not the offspring either of wifJcni or vigour. If the mother-country had a right to Icglflite in all cafes for America, obedience to the (lamp-ail; Ihonld cirlainly have been enforced; and the miniltry which relinquilh- ed an acknowledged right, to gratify tlie faelious dif- pofition of dillant colonies, was obvioully unfit to guide the helm of a great empire. Lord Rockingham and his friends were accordingly difmilTed from office ; and a new adminiftration was formed under the aufpices of Mr Pitt, now created earl of Chatham. Burke, in the mean time, wrote in defence of the party with which he was conncAtd; and affum.ed great credit to it for compofing the dillradtions of the Bri- tifh empire by the repeal of the American ftamp-aft, ■whilll the conftitutional fiiperiority of Great Britain was preferved by the a& for fecuring the dependence of the colonies. After defending his friends, he pro- ceeds to attack thofe who had fucceeded them in office. Of Lord Chatham he fays — " He has once more deign- ed to take the reins of government into his own hand, and will, no doubt,, drive with his wonted fpeed, and raife a deal of dull around him. His horfes are all matched to his mind ; but as fome of them are young and ikittifh, it Is faid he has adopted the new contri- vance lately exhibited by Sir Francis Delaval on Weft- •mlnfler bridge : whenever they' begin to fnort and tofs up their heads, he touches the fpring, throws them loofe, and away they go, leaving his lordfliip fafe and fnug, and as much at his eafe as if he fat on a wool- pack." The letter, of which this is an extraft, was printed in the Public Advertifer ; and is faid to have contribu- ted, in no fmall degree, to lelfen the popularity of the illuftrious (latefman againll whom it was written. The miniftry, indeed, which he had formed, confided of very heterogeneous materials, and was not heartily ap- proved of by the nation. It therefore foon fell In pieces by its own difcord, and Lord Chatham retired in difgufl. The parliament being dilTolved in 1768, Burke was re-eledled for Wendover, and took his feat, when the houfe met, in November. The duke of Grafton was now prime minifter, and was oppofed by two powerful parlies in parliament ; that of the marquis of Rocking- ham, and. that of which Mr Grenville was confidered as the leader. Thefe two parties, however, differed widely betveen thcmfelves. Mr Grenville had pub- liflied a pamphlet, intitkd, Tke Prejent State of the Na- tion ; in which he very ably vindicated his own mea- fiircs, and of courfe condemned the mcafures of thofe who had fucceeded him ; and Burkt replied to him, with greater eloquence, but perhaps with lefs of argu- ment. In a traft, intitled, Obfervalions on the Prefent State of the Nation, in which he makes a very high panegyric on his own patron, and the connexions of the party, and animadverts with cutting feverity on their fuccelTora in ofBce. 38 ] BUR About thii period commenced the national frenzy Burlte. which was excited by the expulfion of Wilkes from the """v^ houfe of commons, yir having printed and pMijhed a feditioiis Hhel, and three objcene and impious libels. In the controverfy to which this tranfaftion gave rife, Burke and Johnfon took oppofite fides. Joiinfon, in his Falfe Alarm, contends, with great ability, that the expulfion of a member from the houfe of commons for the com- miffion of a crime, amounts to a difqualilication of that member from fitting in the parliament from which he is expelled ; whilll Burke, though he difapproved of the condudt of Wilkes as much as his friend, laboured to prove, that nothing but an aft of the legiflature can difqualify any pcrlon from fitting in parliament who is regularly chofen, by a majority of eledlors, to till a va- cant feat. It does not appear that this difference of opinion produced the fmalleil abatement of mutual re- gard between him and Johnfon. They both attended the weekly club, and were as much pleafed with each other as formerly. The proceedings of the Grafton adminlflration, re- fpedling Wilkes and other fubjetls, gave rife to the ce- lebrated Letters of Junius. That thofe compolitions were, in clearnefs, neatnefs, and precifion of flyle, in- finitely fuperior to perhaps every other feries of iiewf- paper inve£lives, has never been controverted; and that they difplay a yafl extent of hiflorical and political in- formation, is known to all who are not themfelves ftrangers to the hiftory of this kingdom. Unclaimed by any author, and fuperior to the produftions of moll authors, they have been given to Burke, to his brother Richard, a man likewife of very bright talents, to Mr Hamilton, and to Lord George Germalne. We fhould hardly hefitate to adopt the opinion of thofe who a- fcribe them to Burke, had he not difavowed them to his friend Johnfon. " I fhould have believed Burke to be Junius (faid Johnfon), becaufe I know no man but Burke who is capable of writing thefe letters ; but Burke fpontaneoufly denied it to me. The cafe would have been different had I ajhed him if he was the au- thor. A man may think he has a right to deny when fo queftioned as to an anonymous pubhcation." The difference between the ftyle of thefe letters and that of Burke's acknowledged writings, would have had no weight with us; becaufe fuch was his command of Ian- , guage, that he could affume, and occafionally did af- fume, any ftyle which he chofe to imitate. He had already fo clofely imitated the very different flyles of Lucas and Bolingbioke as to deceive the public ; and what was to hinder him from imitating the flyle of Lord George Germalne, which certainly has a (Irong rcfemblance to that of Junius ? We think, however, with Johnfon, that liis fpontaneous difanioiual of thefe letters ought to be held as fufficient proof that he was not their author. Burke had now gotten a very pleafant villa near Bea- consfield in Bucklnghamfhire ; and being one of the freeholders of the county, he drew up a petition to the king, complaining of the conduft of the houfe of com- mons refpefting the Middlefex eleftion, and praying for a diffolution of the parliament. The petition, though explicit and firm, was temperate and decorous, and as unlike to one on the fame fubjedt from the livery of London, as the principles of a moderate Whig are to thofe of a turbulent democrate. About BUR [ 139 J BUR About this period he ftated very clearly his own 'political principles in a pamphlet intitled, "Thoughts on the Caufes of the Prcfent Difcoiitents ;" and his plan for removing thefe difcontents had not a grain ot democracy in its compofition. He propofed to place the government in the hands of an open ariftocracy of talents, virtue, property, and rank, combined together on avowed principles, and fupported by the approba- tion and confidence of the people ; and the arittocracy which he thought fitted for this great truft, was a combination of thofe Whig families which had moft powerfully fupported the revolution and confequent efta- blifhmeiits. He exprefitd, in ilrong terms, his dilappro- bation of any change in the conftltutlon and duration of parliament j and declared himfelf as averfe from an adminilbation which fhould have no other fupport than popular favour, as from one brought forward merely by the Influence of the court. In this plan there is not that wifdom or liberality which might have been expefted trom a man of Burke's cultivated mind and exteniive reading. The Whigs, when in power, had been as venal as the Tories ; and the imprifonment of Lord Oxford, the banilhnient of Atterbury bilhop of Rochefter, and the rtfolution of the houfe of commons to fit for feven years, when it had been chofen by its conftituents for no more than three, were certainly greater violations of the conftitu- tion than the difqualilication of Wilkes, or any other meafure that had been carried by the court during the adminiilrations of Grenville and the duke of Grafton. Burke fliewed himfelf in this publication to be indeed no republican ; but every fentcnce of it breathed the fpirit of party. Lord North was now prime minifter ; and in order to tranquillize America, he propofed, in the beginning of his adminilbation, to repeal the obnoxious laws of his predccefTors in office, and to referve the duty on tea merely to maintain the authority of parliament. The conftquences of this conduct we have detailed ehtwhere (lee Britain, Encych); and they are too well known to all our readers. The part which Burke afted du- ring his adminillration will not, in our opinion, admit of any plauilble defence. It was not indeed the part of a democrate, but of a man determined to oppofe every meafure of thofe in power. In the beginning of the conteft, he certainly difplaycd more wifdom and patriotifm than the minifter ; for, without entering di- rectly into the queftion. Whether the mother country had or had not a right to tax the colonies ? he content- ed himfelf with warning the houfe againll dangerous innovations. "The Americans (faid he) have been very ferviceable to Britain under the old fyltem : do not, therefore, let us enter ralhly upon new meafures. Our commercial interefts have been hitherto greatly promoted by our friendly intercourfe with the colonies; do not let us endanger polTeflion for contingency ; do not let us fubftitute untried theories for a fyllem expe- rimentally afcertained to be ufeful." This was undoubtedly found reafoning, and everyway becoming a lover of his country : but his continued op- pofition to government, after all Europe had leagued againft Great Britain, was a conduft which will admit of no vindication, and for which the only poflible apo- logy muft be found in that ardour of temper which made his friend Hamilton fay, on- another occafion. " Whatever opinion Burke, from any motive, fupport?, Burke fo duftile is his imagination, that he foon conceives it *— ~Y~- to be right." In his moft violent oppofitiou, however, though his exprefilons were often extravagant and in- decent, he never for a moment gave his fupport to the metaphyfical dodrlne of t\\t: impnj'jriptibk rights of nhiii, or to the aftual innovations which fome meant to in- troduce on the bafis of that doftrine. His upright mind was indeed fufficiently guarded againft thefe no- velties by what he had obfei ved in Fiance during the year 1772. Whilft he remained in that country, his literary and political eminence made him courted by all the anti-monarchical and infidel philofophers of the lime; and in the religious fcepticifm and political theories of Voltaire, Helvetius, Roufleau, and D'Alembert, he faw, even at that period, the probable overthrow of religion and government. His fentinients on this fubjedt he took occafion, immediately on his return, to communi- cate to the houfe of commons ; and to point cut the confpirac'y of atheifin to the watchful policy of every government. He profefled that he was not over-fond of calling in the aid of the fecular arm to fupprefs doc- trines and opinions ; but he recommended a grand al- liance among all believers againft thofe minifters of re- bellious darknefs, who were endeavouring to ftiake all the works of God eftablilhed in beauty and in order. The American war proving unfuccefsful, though Great Britain never made a more glorious Hand, Lord North and his friends retired from office ; and, in Fe- bruary 1782, a new miniftry was formed, at the head of which was placed the marquis of Rockingham; Lord Shelburne and Mr Fox were the fecretaries of ftate ; and Mr Burke, who was appointed pay-mailer to the forces, exulted, rather childiflily, in the houfe of com- mons, on the happinefs which was to accrue, both to the king and to the people, from the able and upright conduct of the new niiiiifters. The time in which the greater part of them continued in oSice was too (hort to permit them to do eilhei much good or much evil. On the ift of July the marquis of Rockingham died ; and the earl of Shelburne being placed at the head of the treafury. Fox and Burke refigned in dif- guft, and, to the artonifhment of the nation, formed the famous coalition with Lord North, whofe meafures they had lo long, and fo vehemently oppofed. In the coalition of North and Burke there would have been nothing wonderful. In the intercourfe of private life, thefe two ftattfmen had always met on terms of friend- fhip and mutual regard ; they had the fame ideas of the excellence of th.e conttitution, and the fame averfion to innovation under the name of reform ; even their ftudies and amufements were very fimilar, being both men of tafte and claffical learning ; and though Burke oppofed the taxation of America by the Britifti parlia- ment, his oppofitiou proceeded rather from motives of prudence and expediency than from any fettled con- viftion that the meafure was unconftitutional. But the political enmity of Fox and North had proceeded, not only to perfonal abufe, but to profcfPions of mutual ab- horrence ; and perhaps there was hardly an unprejudi- ced perfon in the kingdom who entertained not fufpi- cions, that the unexpefted union of fuch enemies was cemented by a principle lefs pure than patriotifm. Mr Pitt was now chancellor of the exchequer ; and when he announced to the houfe of commons the peace S z which BUR [, I Burl:c. which was conchiikd in J,iniiai7 178^, he foiinJ the V ' terms on which it had bei 11 marie i'everely condemned by Korth, Fox, Burke, and all their friends. The cen- fiire pafled on it by Lord North and his followers was perfcilly confillent with their former conduft, and with the opinions which they had uniformly maintained ; but it was with no good grace that Fox and Burke, who had offered an unconditional peace to the Dutch, and fo frequently propofed to recognize the indepen- dence of America, condemned the peace which had been concluded by Lord Shelburne. On this, as on many other occafions, they afted, not as enlightened politi- cians, but as the rancorous leaders of a party. In confequence of a vote of cenfure pafTed by the commons, the minifters refigned their employments, and were fucceeded by the dnke of Portland, Lord North, ]\Ir Fox, Mr BiM-ke, and their friends. Burke had his form.er employment of paymafler to the forces ; Lord North and Mr Fox were fecretaries of flate, and the duke of Portland was firft lord of the treafury. To many perfons this minlttry had the appearance of greater ftrength than any that had governed the kingdom fince the time of Sir Robert Walpole ; but its duration was not longer than that of the preceding. On the i8th of November, Mr Fox introduced his famous India-bill, into the merits of which it is foreign from our purpofe to enter: fufBce it to fay, that after being ftrongly fup- porttd by Burke, and ably oppofed by Pitt and Dun- das, it paflcd the houfe of commons by a very great ma- jority ; but was loft in the houfe of peers, and viewed by the king in fuch a light, that he determined on an entire change of adminiflration. Mr Pitt was now placed at the head of the treafury, where he has remained ever fince (1800), notwithftand- ing the violent and powerful oppofition which he met v/ith at firft from North and Fox and their coalefced friends : the voice of t!ie nation has been on his fide ; and that voice will always drown the bellowings of pa- triot ifm. The principal events in which Burke fignalized hlm- fclf, fince the year 1784, were the trial of Haftings, the deliberations of the houfe on the propofed regency during the lamented illnefs of the king, and the French revolution ; and on each of thefe occafions he ditplayed talents which aftoniftied the nation. He has, indeed, been feverely blamed for the pertinacity with which he profecuted Mr Haftings, and his conduft has been at- tributed to very unworthy motives ; but of this there is neither proof nor probability. The temperament of his mind vtas fuch, that, into whatever meafure he en- tered, he entered with a degree of ardour of which cooler heads can hardly form a conception. Burke was but one member of a committee which found, or thought it found, evidences of the guilt of Haftings ; and, in forming his opinion, it is little likely that he (hould have been biaffed by intereft or refentment, whofe delicate fenfe of rectitude would not permit him to re- tain a penfion when he could no longer fupport the party of that friend v/ho had obtained it for him. When the eftabliihment of a regency was thought neceifary, he took the part, as it was called, ot the Prince of Wales, in oppofition to the plan propofed by Lord Thurlow and the minifter ; and we doubt not but he was actuated by the pureft principles : but the language which he ufed ia the houfe was vehement, 40 ] BUR and fon^e of his exprcflions were highly indecent. Our reeard for his memory makes us wifli to forget them. Soon after the recovery of the king, the attention of Burke was attracted to the moft momentous event of modern times ; — an event which has convulfed all Eu- rope, and of which, from the very firft, his fagacity forefaw the conlequences. Many of his friends in Par- liament, as well as numbers of wile and good men out of it, augured, from the meeting of the ftates-general of France, great benefit to that nation, of which the government was confidered as defpotic and opprefiive ; and fome were fanguine enough to prognofticate a new and happy order of things to all the nations connefted with France, when its government ihould become more free. Burke thought vtiy differently : He was well acquainted with the genius of the French people, and with the principles of thofe philofophers, as they called themfelves, by Vv'hom a total revolution in church and ftate had long been projefted; and from the commence- ment of their career in the conftituent affembly, when they eftablifhed, as the foundation of all legal govern- ment, the metaphyfical dofirine of the rights of man, he predicted that torrent of anarchy and irreligion which they have fince attempted to pour over all Europe. Fox and fome of the other leading men in oppofition affefted to confider this as a vain fear ; and a coolnefs took place between them and Burke, though they ftill afted together in Parliament. At laft, perceiving the French doftrines of liberty and equality, and atheifm, fpreading through this nation, not only among thofe who had talents for fuch difquifitions, but in clubs and focieties, of which the members could be no judges of metaphyfical reafonings, he expreffed his apprehenfion of the confequences in the houfe of commons. This brought on a violent altercation between him and Fox, who was fupported by Sheridan ; and a rupture took place between thefe old friends which was never healed. He no more attended the meetings of the oppofition members ; and in 1790 he publiftied his celebrated Re- jledions en the French Revolution. By the friends of government this work was admired as the moft feafonable, as well as one of the ableft, de- fences of the Britifh conftitution that ever was written j whilft Fox and his friends, with the great body of Eng- lifh diffenters, though they admitted it to be the oif- fpring of uncommon genius, affefted to confider it as declamatory rather than argumentative, and as incon- fiftent with tlie principles which its author had hitherto uniformly maintained. Many anfwers were written to it ; of which the moft confpicuous were V'lndiciir Gallicce by !Mr Mac Intofh, and The Rights of Man by Thomas Paine. To thefe Burke deigned not to make a direft reply. He vindicated his general principles, as well as fome of his particular reafonings, in A Letter to a Mem- ber of the National AJfemlly ; and he very completely evinced the confiftency of his principles in his Appeal from the Neiu to the Old Whigs. Of this great work, for great it undoubtedly is, the merits as well as the demerits have been much exagge- rated ; and fome have made it a queftion, Whether it has on the whole been produdive of good or harm ? By the enemies of the author, it is reprefented as ha- ving given rife to the fpirit of difcontent, by exciting fuch writers as Paine and his adherents, who, but for the provocation given by The ReJleSions, might have remained B.i'l^e. BUR [I remained in filencc and obfcnr'ty, Tli;3 was from the "^ firft a very improbable fuppofition ; for the fplrit of de- mocracy has at all times been relllcfs : but fnice the ap- pearance of Profeflbr Robiloii's Proofs of a Con/piracy, and Bairuel's Hijlory of jfacobitiifm, it mud be known to every reader to be a fuppofition contrary to faft. The confpirators were bufy long before Burke wrote his Refiedians ; and the friends of order and religion are his debtors, for having fo forcibly roufed them from their flumber, and put them on their guard. With re- fpeft to compolition, it is certainly neither fo energetic nor fo argumentative as the political trajits of Johnfon, to which forne have affeiSed to confider it as fuperior : but it is more poetical, gives fcope for a greater diiplay of the knowledge of human nature; and, being written on a more intereillng fubjedl, it has had a much great- er number of readers than thofe unrivalled pieces of po- litical controverly. Burke being now aifociated with Mr Pitt, continued to write from time to time memorials and remarks on the ftate of France, and the alliance that was formed againft the new order of things in that diftrafted coun- try, of which fome have been publilhed fmce his death ; and having refolved to quit the buftle of public life as foon as the trial of Mr Haftings fliould be concluded, he vacated his feat when that gentleman was acquitted, and retired to his villa at Beaconsfield, where, on the ad of Auguil 1794, he met with a heavy dom^ic lofs in the death of his only fon. In the beginning of the fame year he had loft his brother Richard, whom he tenderly loved : but though this reiterated ftroke of death deeply affefted him, it never relaxed the vigour of his mind, nor lelTened the intereft which he took in the public weal. In this retreat, while he was labouring for the good of all around him, he v.'as difturbed by a very unprovoked attack upon bis chnrafter by forae diilinguiflied fpeakcrs in the houfe ^.^i Peers. Soon after the death of his fon the king was gracioufly pieafed to beftow a penfion on him and Mrs Burke; and this thofe noble lords were plcafed to reprefent as the rewardof what they termed the change of his principles and the defertion of his friends. The injnilice of this charge muft be obvious to every impar- tial mind, lince the penfion was given after he had re- tired from parliament, and could not by his eloquence either fupport the niinillry or gall the oppofitlon. He was not a man to fubmit tamely to fuch an infult. He publi(hed a letter on the occafion, addreffcd to a noble lord (Earl Fitzv.-ilh'am), in which he repels the attack on his charafter, and retaliates on thofe by whom it was made, in terms of fuch eloquent and keen iarcafm, as will be read with admiration as long as the language of the letter rtiall be underftood. Burke having employed every eff<)rt which benevo- lence and wifdor.i could devife to illmulate civilized go- vernments to unite in oppoGtion to the impiety and anarchy of France, laboured likewife in private to re- lieve thofe who had fuffered exile and profcription from the direful fyitem. Through his influence a fchool was eftabliflied in his neiglibourhood for the education of thofe whofe parents, fur their adherence to principle, were rendered unable, to afford to their children ufeful inilruftion ; and that fciiool, which on his deathbed he recoir.mended to Mr Pitt, continues to flourilh under bis. powerful protediion. 41 ] BUR When the appearance of melioration In the principles and government of France induced our fovcreign to make overtures of peace to the French diredtory, Burke refumed his pen ; and in a feries of letters, intitled, Thoughts on the Profpea of a Regicide Peace, difpla)e(l a force of genius which is certainly not furpatfed, and perhaps not equalled, even in his far-famed Rcflcaions on the French Revolution. This was his laft work, and was confidered by himfelf as in its nature teftamen- tary. From the beginning of June 1797 his health rapidly declined ; but his underftanding exerted itfelf with un- diminifhed force and uncontrafted range ; and his dif- pofitions retained all their amiable fweetnefs. On the 7th of July, when the French revolution was mentioned, he fpoke with pleafure of the confcious redlitude of hi.^ own intentions in what he had done and written refpeft. ing It ; entreated thofe about him to believe, that if any unguarded expreihon of his on the fubjeft had offended any of his former friends, no offence was by him in- tended ; and he declared his unfeigned forglvenefs of all who had on account of his writings, or for any other caule, endeavoured to do him an injury. On the day following he defired to be carried to another room ; and whiUl one of his friends, aflifled by fome fervants, was complying with his requcft, Mr Burke faintly ut- tering, " God blefs you," fell back and expired in the 68th year of his age. From this detail, we trufl that our readers are already fufficiently acquainted with his general charaftcr. In genius, variety of knowledge, and readinefs of expref- fion, Johnfon alone of all his contemporaries could be confidered as his rival; and, like that great man, he took every opportunity, efpecially during his lail illnefs, to declare his unfliaken belief of tlie Chriftian religion, his veneration for fincere Chrlftlans of all perfuafion?, and his own preference of the church of England. On the worflilp of that church he had Indeed through the whole of his life been a regular and devout attendant ; and the tears which the poor, in the neighbourhood t-.i his villa, (hed at his funer;;!, gave fufificient evidence that his faith had been produiHve of charity. In his public conduft, the Irritability of his temper, and the ardouv of his imagination, fometlmes hurried him into tlie ix- ceffes of a mere party-num ; but we believe tl,at Ins great religious and political principles never varied. Be has himfelf charaCterifed his public conduA in the con- clufion of his Reflecflons on the French Revolution, when he fay?, that " they come from one who has been no tool of power, no flatterer of greatnefs, and who in his laft afts docs not wiih to belie the tenor of his life;, from one who wifhes to preferVe confiftency, but who would preferve confiftency by varying his means to fe. cure the unity of his end; snd when the equipoife of the veffel in which he fails may be endangered by over- loading it upon one fide. Is defirous of cari-vln;j the fmall weight of his reafons to that which mayprcfei-ve the equipoife." BURNET (James, Efq;), better known by the title of Lord Aloniodt'o, defcended from- an ancient fa. mily In the county of MeaiTis in Scotland. He was the tldeft fon of Arthur Burnet, Efq; of Monhoddo, wlierj he was born in the year 1714. After pafiing throujli the ufual courfe of fchool education, he profeeuted hli ftudies at the univcifilics of ALerdecn, Edinburgh, ani L.cyde;)j, Bu-kf, Euinct. V— V .J BUR [ H Burnet. Leydin, with diftinguilhcd reputation. He was admit- 'ted an advocate in 1737 ; and on the 12th of February J 767, he was raifed to the bench, by the title of Lord Monboddo, in the room of Lord Milton, ajipointcd a judge the 4th of June 1742, and who had lucceeded Sir John Lauder of Fountainhall, admitted November I. 16^9 ; fo that he was only the third judge in fucccf- fion fince the revolution. Before his promotion to the bench, he had married Mifs Farquharfon, a very amiable woman, by whom he had a fon and two daujjhters ; whom, without reirard- ing the diflerence of climate, he reared as the childrefl of ancient Greece were reared. From early youth Lord Monboddo's application to literary and juridical ftudies was feverely diligent. Be- tween claffical literature and the law of Scotland, there exifts a ftrong connexion, arifing from the adoption of the forms and maxims of the civil law of the Romans, by the ancient legiflators and judges of Scotland. Ac- cordingly, while Mr Burnet rofe into reputation as a lawyer, he at the fame time improved into profound erudition that knowledge of the Greek and Roman authors which he had acquired at fchool and the uni- verfity ; and his partiality to the Greek language could 'not fail to be ftrengthened by his frequent converfa- tions with Dr Blackwell, the celebrated profelTor of that language in the Marifchal College and Univcrfity of Aberdeen. His favourite ftudies, however, were not fufFered to interfere with his duty as a judge. In his native coun- ty, his integrity as Sheriff will be long remembered ; and during the whole time that he was a Lord of Sef- fion, he difcharged the duties of his high office with an affiduity, a patience, a clear intelligence, and inflexible reftitude, which did honour to the court of which he was a judge. Like others, he was liable to error ; but neither the awe of power, the blandilhments of flat- tery, nor even compafTiun for dillrefs, could turn Lord Monboddo afide from what he believed to be the courfe of juftice. Several of the judges of the court of feflion were at that period ambitious of fliining among philofophers and men of tafte ; and I>ord Karnes's Elements of Cri- tkifm is a work which will be long read, and always ad- mired. It was not, however, admired by Lord Mon- boddo ; and he determined to vindicate the fuperiority of the ancients over the moderns, as well in philolophy as in belles Icttres. With this view he published, in 1773, the firft volume of his Origin and Progress of Lan- guage ; whicli wasperufed with mingled fentiments of refpeft and indignation. It was better received in Eng- land than in his own country ; and notwithilanding the ridicule brought upon him by his belief in the exiilence of mermen, and men nvith tails, the author felt himfelf fufficiently encouraged to complete his plan in five vo- lumes. Having, as he thought, vindicated Grecian literature, he was induced to undertake another great work in de- fence of Grecian philofopljy, againll the ftill more arro- gant claims, as he deemed them, of Bacon and New- ton, with their followers. With this view, he publifli- ed, at different times, and in fix volumes 4to, a work intitled Jncient Metaphyftcs, fraught, it muft be confef- fed, with much erudition, much good fenfe, and, Itrange as the combination may feem, with much abfurdity. In 2 ] B U 11 the preface to tlie firft volume, he declares open war Burnet, againft all modern writers of philofophy, except Mr iT"" Harris, who was an adorer of the ancients like himfelf, Mr Baxter, and Dr Cudworth. He acknowledges Bax- ter's- book on the Immateriality of the Soul to be a truly valuable work ; and lays of Cudworth's IntelleHual Syliem, that he agrees with it throughout. There is indeed fuch a coincidence of notions in the IntelleSual Sy/lem and the Aticicnt Metaphyftcs, that an ill-natured critic might be tempted to fufpeft, that every thing valuable in the latter was borrowed from the former. The Ancient Metaphyftcs had few admirers in Scot- land ; but it procured for its author, from a frholar of Oxford, we think Mr Huntingford, the title of at^Km Apitr7i7i^Bc. His Lordfliip continued to cultivate what hj? called Greek philcfophy, and to attend his judicial du- ties, with indefatigable diligence till within a few days of his death, which happened at his houfe in Edinburgh, on the 26th of May 1799, at the advanced age of 85. His private life was fpent in the prattice of all the focial virtues, and in the enjoyment of much domelUc felicity. Although rigidly temperate in his habits of life, lie, however, delighted much in the convivial focie- ty of his friends ; and among thefe he could number almoft all the moft eminent of thofe who were diftin- guifhed in Scotland for virtue, literature, or genuine elegance of converfation and manners. His fon, a very promifing boy, in whofe education he took great de- light, was fnatched away from his affeftions by a pre- mature death. But when it was too late for forrow and anxiety to avail, the afflifted father ftifled the emo- tions of nature in his breaft, and wound up the energies of his foul to the firmeft tone of ftoical fortitude. He was, in like manner, bereaved of his excellent lady, the objeft of his deareft tendernefs ; and he endured the lofs with a fimilar firninefs, fitted to do honour either to philofophy or to religion. In addition to his office as a judge in the court of feflion, an offer was made to him of a feat in the court of jufticiary. But though the emoluments of the office would have made a convenient addition to his income, he refufed to accept it, left its bufinefs (hould too much detach him from the purfuit of his favourite ftudies. The vacations of the court of feffion afforded him fiif- ficient leifure to retire every )'car, in fpring and in au- tumn, to the country ; and be ufed then to drefs in a Ityle of iimplicity, as if he had been only a plain far- mer ; and to live among the people upon his eftate with all the kind familiarity and attention of an aged father among his grown-up children. Although the eftate, from the old leafes, did not afford an income of more three or four hundred pounds a-year, he would never raife the rents upon his old tenants, nor difphce an old tenant, for the fake of any augmentation of emolument offered by a richer or more enteqinfing ftranger In imitation of the rural economy of fome of the ancients, whom he chiefly admired, he accounted population the true wealth of an eftate, and was defirous of no other improvement of his lands, than that of having the num- ber of perfons that ftiould refide upon them, and be luf- tained by their produce, fuperior to that of the popula- tion of any equal portion of the lands of his neighbour.s. It was at Monboddo that he had the pleafure of receiving Dr Samuel Johnfon, with his friend James Bofwell, at the time when thefe two gentlemen were upon BUR r H3 ] BUR Burnet, upnn their well-known Tour tlirough the Highlands ""^ 'of Scotland. Johnfon admired nolliing in literature {o much as the difplay of a keen dilcrimination of hu- man charader, a juft apprehenfion of the principles of moral aftion, and that vigorous common fenfe which is the moll happily applicable to the ordinary con- duct of life. Monboddo delighted in the refinements, the fubtleties, the abftradlious, the affectations, of li- terature ; and, in comparifon with theie, defpifed the grolTnefs of modern taite and of common aflairs. John- ion thouglit learning and fcience to be little valu- able, except fo far as they could be made fubfervient to the purpofes of living ufcfully and happily with the world upon its own terms. Monboddo's favourite fcience taught him to look down with contempt upon all fublunary, and efpecially upon all modern things ; and to fit life to literature and philofopl)y, not litera- ture and philofophy to life. James Bofwell, therefore, in carrying Joiuifon to vilit Monboddo, probably thought of pitting them one againft another, as two game cocks, and promifed himfelf much fport from the colloquial conteft which he expeAcd to cntje between them. But Monboddo was too hofpitable and courteous to enter into keen contention with a llranger in his own houfe. There was much talk between them, but no angry con- troverfy, no exafperation of that diflike for each other's well-known peculiarities with which they had met. Johnfon, it is true, ftill continued to think Lord Mon- boddo what he called a prig in literature ; and Mon- boddo to cenfure Johnfon for allowing the moderns, in fome things, to furpafs the ancients. Lord Monboddo ufed frequently to vifit London, to which he was allured by the opportunity that great me- tropolis affords of enjoying tlie converfution of a vaft number of men of profound erudition. A journey to the capital became a favourite amufement of his periods of vacation from the buiincfs of the court to which he belonged; and, for a tim.e, he made this journey once a-year. A carriage, a vehicle that was not in common ufe among the ancients, he confidcred as an engine of effeminacy and fioth, which it was uifgraceful for a man to make ufe of in travelling. To be dragged at the tail of a horfe, inltead of mounting upon his back, feemed, in his eyes, to be a truly ludicrous degradation of the genuine dignity of human nature. In all his journeys, therefore, between Edinburgh and London, he was wont to ride on horfeback, with a fingle fervant attending him. He continued this praidly filled ; and it was fuppofed that the poet nn'ght derive from the fub- fcription and the fale of his copy-right a clear profit ot at leall 700 pounds. The converfatlon of even the mofl eminent authors is often found to be fo unequal to the fame of their writings, that he who reads with admiration can liilen with none but fentiments of the mod profound contempt. But the converfatlon of Burns was, in comparifon with the formal and exterior circumftances of his education, perhaps even more wonderful than his poetry. He af- fefted no foft air or graceful mc>tions of politencfs, which might have ill accorded with the ruflic plainnefs of his native manners. Confcious fuperiority of mind taught him to aflbciate with the great, the learned, and the gay, v\lthout being overawed into any fuch baihful- nefs as might have made him confufed in thought, or hefitating in elocution. He ponVfled withal an extra- ordinary fhare of plain common fenle or mother-wit, which prevented lilm from obtruding upon perlons, of whatever rank with whom he was admitted to converfe, any of thofe clTufions of vanity, envy, or felf conceit, in which authors are exceedingly apt to indulge, who have lived remote from the general praclice of li(e, and whofe minds have been almofl exclufively confined to contem- plate their own ftudies and their own works. In con- verfatlon he difplaycd a fort of intuitive quicknefs and .re6t)tude of judgment upon every fubjecl that arofe. The fenfibility of his heart, and the vivacity of In's fan- cy, gave a rich colouring to whatever re;vn converfatlon wai not at all lefs happy than in his writings. For thefe reafons, thofe who had m< t andconvcrfed with hhn once, were pleafcd to meet and to converfe with hrni again and again. For fome time he convcrftd only with the virtuous, T ihr BUR Burnt, the learned, and the wife ; and the purity of his morals ""■v"—' remained uncontaminated. But, ahs ! he fell, as others have fallen in fimllar circuniftances. He fulFercd liim- felf to be fiuTOunded by a race of miferable beings, who were proud to tell that they had been in company with Burns, and had feen Burns as loofc and as foolifh as themfelves. He was not yet irrecoverably loft to tem- perance and moderation ; but he was already almoft too much captivated with their wanton revels, to be ever more won back to a faithful attachment to their more fober charms. He now alfo began to contratl fomething of new arrogance in converfation. Accuf- tomed to be among his favourite affoclates what is vul- g*rly but expreflively called ihe cock of th; company, he could fcarcely refrain from indulging in funilar freedom and dictatorial decifiou of talk, even in the prcfence of perfons who could lefs patiently endure his prefump- tion. The fubfcription-edition of his poems, in the m.ean time, appeared; and although not enlarged beyond that which came from the Kilmarnock prefs by any new pieces of eminent merit, did not fail to give entire ia- tisfaftion to the fubfcribers. He was now to clofe ac- counts with his bookfeiler and his printer, to retire to the country with his profits in his pocket, and to fix upon a plan for his future life. He talked loudly of independence of fpirit and fimplicity of manners, and boalied his refolution to return to the plough ; yet ftiU he lingered in Edinburgh, week after week, and month after month, perhaps expetting that one or other of his noble patrons might procure him fome permanent and competent annual income, which (hould fet him above all neceffity of future exertions to earn for himfelf the means of fubfiftence; perhaps unconfcioudy nluftant to quit the pleafurec of that voluptuous town-life to which he had for fome time too willingly accuftomed himfelf. An accidental dlflocation or frafture of an arm or a leg confining him for fome weeks to his apartment, left him during this time leifure for ferious reflection ; and he determined to retire from the town without longer de- lay. None of all his patrons intcrpofed to divert him from his purpofe of returning to the plough, by the of- fer of any fmall penfion, or any finecure place of mode- rate emolument, fnch as might have given him compe- tence without withdrawing him from his poetical ftu- dies. It feemed to be forgotten that a ploughman thus exalted into a man of letters was unfitted for his for- mer toils, without being regularly qualified to enter the career of any new profefGon ; and that it became in- cumbent upon thofe patrons who had called him from the plough, not merely to make him their companion in the hour of rio^, not limply to fill his purfe with gold for a few tranfieut expences, but to fecure him as far as was pofTible from being ever overwhelmed in diftrefs in confequence of the favour which they had fliown him, and of the habits of life into which they had fcduced him. Perhaps indeed the fame delufion of fancy be- trayed both Burns and his patrons into the miftaken idea, that, after all which had paffed, it was ftill poffible for him to return in cheerful content to the homely joys and iimple toils of undiffipated rural life. In this temper of Burns's mind, in this ftate of his fortune, a farm and the excife were the objefts upon which his choice ultimately fixed fo? future employment and fupport. By the furgeon who attended him during [ 146 ] BUR his illnefs, he was recommended with efTeft to the com- Burnt. miflioners of excife ; and Patrick Millar, Efq. of Dal- '~"~v~~' fwinton, deceived, like Burns himfelf and Burns's other friends, into an idea that the poet and excifeman might yet be refpeftable and happy as a farmer, generouily propofcd to eftablifh him in a farm, upon conditions of leafe which prudence and induftry might eafily render exceedingly advantageous. Burns eagerly accepted the offers of this benevolent patron. Two of the poet's friends from Airfhire were invited to fuivey that farm in Dumfriesdiire which Mr Millar offered. A leafe was granted to the poetical farmer at that annual rent which his own friends declared that the due cultivation of his farm might eafily enable him to pay. What yet remained of the profits of his publication was laid out in the purchafe of farm-llock ; and Mr Millar might, for fome fliort time, pleafe himfelf with the perfuafion that he had approved himfelf the liberal patron of ge- nius ; had acquired a good tenant upon his eilate ; and had placed a deferving man in the very fituation in which alone he himfelf defired to be placed, in order to be happy to his wifhes. Burns, with his Jane, whom, he now married, took up their refidence upon his farm. The neighbouring farmers and gentlemen, pleafed to obtain for an inmate among them the poet by whofe works they had been delighted, kindly fought his company, and invited him to their houfes. He found an inexpreflible charm m. fitting down btfide his wife, at his own firefide ; in wandering over his own grounds; in once more putting his hand to the Ipade and the plough ; in forming his enclofures, and managing his cattle. For fome months he felt almoft all that felicity which fancy had taught him to expeft in his new fituation. He had been for a time idle ; but his mufcles were not yet unbraced for rural toil. He now feemed to find a joy in being the hufband of the miftrefs of his affedlions, in feeing him- felf the father of her children, fuch as might promife to attach him for ever to that modell, humble, and domef- tic life, in which alone he could hope to be permanent- ly happy. Even his engagements in the fervice of the excife did not, at the very firft, threaten neceffarily to debafe him by affociation with the mean, the grofs, and the profligate, to contaminate the poet, or to ruin the farmer. But it could not be : it was not poffible for Burns now' to affume that fobernefs of fancy and pafTions, that fedatenefs of feeling, thofe habits of earneft attention to grofs and vulgar cares, without which fuccefs in his new fituation was not to be expefted. A thoufand difficul- ties were to be encountered and overcome, much money was to be expended, much weary toil was to be exer- cifed, before his farm could be brought into a ftate of cultivation in which its produce might enrich the oc- cupier. This was not a profpeft encouraging to a man who had never loved labour, and who was at this time certainly not at all difpofed to enter into agriculture with the enthufiafm of a projeftor. The bufinefs of the excife too, as he began to be more and more employed in it, diilrafted his mind from the care of his farm, led him into grofs and vulgar fociety, and expofed him to many unavoidable temptations to drunken excefs, fuch as he had no longer fufHcient fortitude to refill. Amidft the anxieties, diltraftions, and feducements which thus arofe to him, home becam.e infenfibly lefs and lefs plea- fm? BUR finff J even the endearments of his Jane's afTcdion be- 'gan to lofe their hold on liis heart ; he became every day lefs and Icfs unwilh'ng to forget in riot thofe ga- thcrinf forrows which he knew not to liibdue. Ml Millar and fome others of his friends would glad- ly have exerted an influence over his mind which might have prefervcd him in this fituation of his affairs, equally from dcfpondency and from diifipation ; but Burns's temper fpiirned all controul from his fuperiors in for- tune. He refented, as an arrogant encroachment upon his independence, that tenor of coiiduft by which Mr Millar wi{hed to turn him from diflolute conviviality, to that Heady attention to the bullnefs of his farm, without which it was inipoffible to thrive in it. His croffes and difappointments drove him every day more and more into diifipation ; and this diffipation tended to enhance whatever was difagreeable and perplexing in the (late of his affairs. He funk, by degrees, into the boon companion of mere cxcifemen ; and almoft every drunken fellow, who was willing to fpcnd his money la- vlflily ill the alehoufe, could eafily command tlie com- pany of Burns. The care of his farm was thus uegl-fl- ed ; wade and loffes wholly confumed his little capital ; he refigned his leafe into the hands of his landlord; and retired, with his family, to ti,e town of Dumfries, de- termining to depend entirely for the means of future fupport upon his income as an excife-ofiicer. Yet during this unfortunate period of his life, which paffed between his departure from Edinburgh to fettle in Dumfriesdiire, and his leaving the country, in order to take up his refidence in the town of Dumfries, the ener- gy and activity of his intclledlual powers appeared to have been not at all impaired. In a colledllon of Scot- tidi fongs, which were publifhed (the words with the mufic) by Mr Johnfon, engraver in Edinburgh, in 4 vols Kvo, Burns, in many inftances, accomniod:ited new verfcs to the old tunes with admirable felicity and Ikill. He affiilcd in the temporary inftitution of a fmall fub- icrrption library, for the uie of a number of the well- difpofed peafants in his neighbourhood. He readily aided, and by his knowledge of genuine Scottiih phra- feolc^y and manners greatly enlightened, the antiqua- rian refcarches of the late ingenious Captain Grofe. He ftill carried on an epillolary correfpondence, fome- tlmes gay, fportive, humorous, but always enlivened by bright flalhea of genius, with a number of his old triends, and on a very wide diverfity of topics. At times, as it (hould feem from his writings of this period, he reflected, with inexprefiible' heart-bitternefs, on the high hopes from which he had fallen ; on the errors of moral conduft into which he had been hurried by the ardour of his foul, and in fome meafure by the very ge- nerofity of his nature ; on the difgrace and wretchednefs into which he faw himfelf rapidly finking ; on the for- row with which his niifcondufl oppreffed the heart of his Jane ; on the want and deftitute mifery in which it feemed probable that he muft leave her and their in- fants ; nor amidft thefe agonizing refleftions did he fail to look, with an indignation half invidious, half con- temptuous, on thofe who, with moral habits not more excellent than his, with powers of intelleft far inferior, yet balked in the fun-fhine of fortune, and were loaded with the wealth and honours of the world, while his follies could not obtain pardon, nor his wants an ho- nourable fupply. His wit became from this time more [ Ml ] BUR gloomily farcaftic ; and his converfation and writings Burni. began to affiime fomething of a tone of mifanthropical ^~~v~~" malignity, by wliicii they had not been before, in any eminent degree, diftinguiflied. But with all thefe fail- ings, he was Hill that exalted mind which had raifcd itfclf above the depreffion of its original condition : with all the energy of the lion, pawing to fet free his hinder limbs from the yet encumbering earth, he Ilill appeared not Icfs than .ircbaiigel ruined ! His morals were not mended by his removal from the country. In Dumfries his diffipation became ftill more deeply habitual ; he was here more expofed than in the country to be folicited to (hare the riot of the diffolute and the idle: foolifii young men flocked eager- ly about him, and from time to time preffed him to drink with them, that they might enjoy his wicked wit. The Caledonian Club, too, and the DumfriesOiire and Galloway Hunt, had occalional meetings in Dumfries after Burns went to refide there, and the poet was of courfe invited to (hare their conviviality, and helitatcd not to accept the invitation. [n th? intervals between his different fits of intem- perance, he fuffered Ilill the keeneft anguilh of rcniorfe, and horribly affliftive foreiight. His Jane ftill behaved with a degree of maternal and conjugal tendernefs and prudence, which made him feel more bitterly the evil of his mifcondudi, although they could not reclaim him. At lail crippled, emaciated, having the very power of animation wafted by difeafe, quite broken-hearted by the fenfe of his errors, and of the hopclefs miferies in which he faw himfelf and his family depreffed ; with, his foul Ilill tremblingly alive to the fenfe of (liame, and to the love of virtue ; yet even in the laft feeblenels, and amid the laft agonies of expiring life, yielding rea- dily to any temptation that offered the femblance of in- temperate enjoyment, he died at Dumfries, in the funi- mer of 1796, while he was yet three or four years un- der the age of forty, furniihing a melancholy proof of the danger of Juddenly elevating even the greateft mind above its original level. After his death, it quickly appeared that his failings had not elfaced from the minds of his more refpeflable acquaintance either the regard which had once been won by his locial qualities, or the reverence due to his intelletfual talents. The circumftances of want In which he left his family were noticed by the gentlemen of Dumfries with earned commifciation. His funeral was celebrated by the care of his friends with a decent fo- . lemnity, and with a numerous attendance of mourners, fulficlently honourable to his memory. Several copies of verfes were inferted in different newfpapers upon the occafion of his death. A contribution, by fubfcrlption, was propofed, for the purpofe of raifing a fmall fund, for the decent fupport of his widow, and the education of his infant children. From the preceding detail of the particulars of this poet's life, the reader will naturally and juftly infer him to have been an honeft, proud, warm-hearted man ; of high paffions and found underftandiug, and a vigorous and excurfive imagination. He was never known to defcend to any aft of deliberate meannefs. In Dum- fries he retained many refpeftable friends even to the laft ; and it may be doubted whether any poet of the prefent age has exerciled a greater power over the minds of his readers. Burns has not failed to command T2 one BUT [ 148 ] BUT Surram. one reitiavkable fort of homage, fuch es is never paid with the mixture appears of a rich marrowy confidence Buter, pooler, Butter. but to great original genius ; a crowd of poetailers and fine colour, and never acquires a brittle hardnefs ' ftarted up to imitate him, by writing verfes as he had nor taftes fait ; the other is comparatively liard and done in the Scottilh dialeft ; but, imitatores ! fcrvum brittle, approaching more nearly to the appearance of To v.'rite rugged rh!mi-s, in antiquated phrafe, is tallow, and is much falter to the tafte. I have ate but- " ' " ~ ter cured with the above compofition that had been kept three years, and it was as fweet as at firft ; but it mufl be noted, that butter thus cured requires to ftand three week& or a month before it is begun to be ufed. If it be fooner opened, the falts are not fufficiently blended with it ; and fometimes the coolnefs of the nitre will then be perceived, which totally difappears after- wards." The following obfervationsrefpefting the proper me- not to imitate tlie poctrv of Burns. BURRAMPOOTER. See Sandpu, Encycl. BUTTER is a fubftancc fo well known, that it is needlcfs to give here any definition of it ; but as it is, in this country at Icall, fo general an article of food, that the proper methods of making and curing it have en- gaged the attention of fome of our ablefl writers on agriculture, in addition to what has been faid on thefe fubjefls under the titles Butter and Dairy (iinfj'^'-) . _ . _ _ . . our readers will probably be pleafed with the following thod of keeping both milk and butter are by the fame method of curing it, which is praftifed by fome farmers author, and we truft may prove ufeful. Speaking ftill in the p;ui(]i of Udney, in the county of Aberdeen, of the county of Aberdeen, he fays, " The pernicious and gives to their butter a great fuperiority above that praftice of keeping milk in leaden veflels, and faking of their neighbours. butter in ftone jars, begins to gain ground among fome Take two parts of the beft common fait, one part of of the fine ladies in this county, as well as elfewhere, A'gar, and one part of faltpetre; beat them up together, from an idea of cleanhnefs. The faft is, it is ju-ft the and blend the whole completely. Tak'e one ounce of reverfe of cleanlinefs ; for in the hands of a careful per- fon nothing can be more cleanly than wooden difhes, but under the management of a flattern they difcover the fecret which ftone diftcs indeed do not. " In return, thefe latter communicate to the butter and the milk, which has been kept in them, a poifon- ous quality, which inevitably proves deftruflive to the human conftitution. To the prevalence of this prac- tice I have no doubt we muft attribute the frequency of palfies, which begin to prevail fo much in this king- this compofition for every 16 ounces of butter, work it ■well into the mafs, and clofe it up for ufe. Dr James Anderfon, from whofe View of the Agri- culture of the County of Aberdeen this receipt is taken, fays, that he knows of no fimple improvement in eco- nomics greater than this is, when compared with the iifual mode of curing butter by means of common fait alone. " I have feen (continues he) the experiment fairly made, of one part of the butter made at one time being thus cured, and the other part cured with fait dom ; for the well known effeft of the poifon of lead is alone : the difference was inconceivable. I fliould fup- bodily debility, paify — death !" pofe that, in any open market, the one would fell for BYSAK, the firlt month of the Bengal year, begia- ^7,0 per cent, more than the other. The butter cured ning in April. c. Caffcs. OAFFRES, the inhabitants of Caffraria, are gene- ^ *-^ rally confounded with the Hottentots ; but, ac- cording to M. Vaillant, there is a confiderable dift'e- rence between the manners, cuftoms, and even appear- ance of thefe two nations. The Caffres, fays he, are generally taller than the Hottentots, more robuft, more fierce, and much bolder. Their figure ris likewife more agreeable, and their coun- tenances have not that narrownefs at the bottom, nor their cheeks thofe prominences, which are fo difagree- able among the Hottentots. A round figure, a nofe not too flat, a broad forehead, and large eyes, give them an open and lively air ; and if prejudice can overlook the colour of the fkin, there are fome Caffre women who, even in Europe, wouM be accounted pretty. Thefe people do not make their faces ridiculous, by pul- ling out their eye brows like the Hottentots; they tat- too themfelves much,, and particularly their bodies ; their hair, which is frizzled very much, is never greafed, but their bodies are liberally anointed, merely with a ,, view to preferve their vigour and agility. The men generally beftow more attention on their drefs than the women, and are remarkably fond of beads and copper rings. The women wear hardly any of the ornaments in which the other favages in Africa take fuch delight. They do not even wear copper brace- lets ; but their fmall aprons, which are ilill (horter than thofe of the Hottentots, are bordered with a few rows of glafs beads ; and in this all their luxury confifts. It would appear that the Caffres are not fo chafte as the Hottentots, becaufe the men do not ufe a jackal to vail what nature teaches other men, even favages, to con- ceal. A fmall cowl, which covers only the glans, in- ftead of difplaying modefty, feems to announce the greateft indecency. This fmall covering adheres to a thoug, which is fafteiied round their girdles, merely that Caffres C A F [ that it may not be loft; for a Caffre, if he be not afraid ■• of being hurt or ilung by infefts, cares very little whe- ther his cowl be in its place or not. Our author faw one Caffre who, Inftead of a cowl, wore a cafe made of wood, and ornamented with fculpture. This was a new and ridiculous fafliion, which he had borrowed from a nation of black people who lived at a great diftance from Caffraria. In the hot feafon the CafFres go always naked, and retain nothing but their ornaments. In cold weather they wear kroITes made of calves or oxen hides, which reach down to the ground ; but whatever the weather he, both fcxes go bare-headed, except that they fome- times, though rarely, fix a plume of feathers in their hair. The Caffre huts are more fpacious and higher than thofe of the Hgttentots, and have alio a more regular form. The frames of them are conftrufted of wooden work, well put together, and very fohd, being intend- ed to lail for a long time: for the Caffres, applying to agriculture, which the free Hottentots do not, remain fixed to one fpot, unlefs fomething unexpedled inter- rupt their repofe. A more perceptible induftr)', an acquaintance with fome of the moft necelfary arts of life, a little know- ledge of agriculture, and a few religious dogmas, feem to announce that the Caffies approach much nearer to civilization than the Hottentots. They entertain a to- lerably exalted idea of the Supreme Being and his power ; they believe that the good will be rewarded, and the wicked punillied, in a future Hate ; but they have no notion of creation, which indeed was not ad- mitted by the fages of Greece and Rome. They prac- tife circumcilion, but can give na account of its origin among them, or of the purpofe for which the practice is continued. Polygamy is ufed among the Caffres ; and on the death of a father the male children and their mothers fhare the fucceffion among them. The girls remain with their mothers without property of anv kind until they can procure hufbands. One very fingulnr cultom of the Calfres is, that they do not, in general, inter their dead, but tranfport them from the krail to an open ditch, which is common to the whole horde. At this ditch favage animals feed at their leifure on the multitude of carcafes which are heaped together. Fu- neral honours are due only to kings and the chiefs of each horde, whole bodies are covered with a heap of flones collefted into the form of a dome. This nation is governed by a general, chief, or king, whofe power is very limited. He appoints, however, the fubordinate chiefs over the different hordes, and through them communicates his direftions or orders. The arms of the Caffre are a cluli, two feet and a half in length, and w here thickeft three inches in diameter, and a plain lance or ajjagey. He defpifes poifoned arrows, which are fo much ufed by fome of the neighbouring nations ; and with his two fimple weapons feeks always to meet his enemy face to face in the field. The Hot- tentot, on the contrary, concealed under a rock or be- hmd a bufh, deals out deftruftion, without being expo- fed to danger. The one is a perfidious tyger, which rufhcs treacheroufly on his prey; the other is a gene- rous lion, which, having given warning of his approach, 149 ] C A L makes his attack boldly, and peridies if he prevail not Culctlus. againfl his antagouill. « CALCULUS, in mathematics, denotes a certain way of performing inveftigations and refolutions, which occur on many occalions, particularly in mechanical phi- lofophy. Thus we fay, the anteci/lental calculus, the algebraical calculus, the arilhmetical calculus, the diffi- renlial calculus, the exponenlial calculus, the Jluxioiml calculus, and the integral calculus. Of by much the greater part of theie cakuli fome account has been given in the Encyclopaedia Britannicd ; but there is one of them, of which no notice has been taken in that work. It is, The Anteccdental Calculus, a geometrical method of reafoning, without any confideration of motion or ve- locity, applicable to every purpofe to which the mucli celebrated doflrine of fluxions of the illuftrious Newton has been, or can be, applied. This method was in- vented by James Glenie, Efq; " in which (he fays) every exprellion is truly and ftridtly geometrical, i.j founded on principles frequently made ufe of by the ancient geometers, principles admitted into the very firll elements of geometry, and repeatedly ufed by Euclid himfelf. As it is a branch of general geometrical pro- portion, or univerfal comparifon, and is derived from an examination of the antecedents of ratios, having given confequents and a given flandard of comparifon in ths various degrees of augmentation and diminution they undergo by compofition and decompofition, 1 have call- ed it the antecedental calculus. As it is purely geo- metrical, and perfeftly fcientilic, I have, llnce it iiril occurred to me in 1779, always made ufe of it inltead of the fluxionary and difl'erential calculi, v.'hich arc inerely arithmetical. Its principles are totally uncon- nec'fed with the ideas of motion and time, which, Itric'b ly fpeaking, are foreign to pure geometry and -^ibftratt fciencc, though, in mixed mathematics and natural plif- Infophy, they are equally applicable to every invelbga- tion, involving the confideration of cither v/ith the tv\.-> numerical methods juil mentioned. And as many iutii inveftigations require compoiitions and decompoiitions of ratios, extending greatly beyond the triplicate and fubtriplicate, this calculus in all ofthern f.irniihes every exprellion in a ftrictly geometrical form. The ilan- dards of comparifon in it may be any magnitudes what- ever, and are of courfe indefinite and innumerable ; and the confequents of the ratios, compounded or decoiii- pounded, may be either equal or unequal, homogentous or heterogeneous. In the fluxionary and difi'ereiuii-.l methods, on the other hand, i, or unit, is not only the flandard of comparifon, but alfo the confequent of cit- ry ratio compounded or decompounded." This method is deduced immediately from Mr Gie- nie's Treatife on the Doiitrine of Univerfal Comparifon or General Proportion : And as the limits of the pre- fent work will not allow us to enter upon this fubiect, we therefore refer our readers to the two above men- tioned treatifes, and to the fourth volume of the Tranf- aflions of the Royal Society of Edinburgh. We confefs, however, that we do not expeift fncfi great advantage from the employment of tills calculus as the very acute and ingenious author feems to promlfc from ft. The mathematical world is truly indebted to him for the clear and dil'criminating view th:,t he lips take a C A L [ >5o 3 C A L Ciltulu5. taken of the dodlrine of univerfal comparifon, and we *" "V believe it to be perfectly accurate, and in fome refpefts new. Notwithftanding the continual occupation of ma- thematicians with ratios and analogies, their particular objefts commonly reftricted their manner of conceiving ratio to fome prefent modification of it. Hence it feems to have happened that their conceptions of it as a mag- nitude have not been uniform. But Mr Glenie, by avoiding every peculiarity, has at once attributed to it all the rr.eafurable affeiflions of magnitude, addition or fubtraftion, multiplication or divifion, and ratio or pro- portion. He is perhaps the firll who has roundly con- fidered ratio or proportion as an affedlion of ratio ; and it is chiefly by the employment of this undoubted affeftion of ratio that he has rendered the geometrical analyfis fo comprehenfive. But when we view this antecedental calculus, not as a method of exprefPuig mathematical fcience, but as an art, as a calculus in (hort, and confider the means which it muft. employ, and the notation which mull be ufed, ■we become lefs fangnine in our hopes of advantage from it. The notation cannot (we think) be more fimple than that of the fiuxionary method, juftly called arith- metical ; and if we infill on carrying clear conceptions along with us, we imagine that the arithmetical expoii- tion of our fymbols will generally be the fimpler of the two. T\k fcience of the antecedental calculus feems to confifl in the attainable perception of all the fimple ra- tios, whether of magnitudes or ratios, or both, which concur to the formation of a compound and complica- ted ratio. Now this is equally, and more eafily attain, able in the fiuxionary or other arithmetical method, when the confcquent is a fimple magnitude. When it is not, the fame proccfs is farther neceflai-y in both me- thods, for getting rid of its complication. We apprehend that it is a miftake that the geome- trical method is more abfirafled than the fiuxionary, becaufe the latter fuperadds to the notion of cxtenfion the notions of time and motion. Thcfe notions were introduced by the illuftrious inventor for the demonjlra- tion, but never occupy the thoughts in the ufe ot his propofitions. Thefe are geometrical truths, no matter how demonllrated ; and when duly confidercd, involve nothing tliat is omitted in the antecedental calculus. We even prefuine to fay, that the complication of thought, in the contemplation of the ratios of ratios, is greater than what will generally arife from the addi- tional elements, time and motion. We do not find that any of our mod aftive mathe- maticians have availed themfelves of the advantages of this calculus, nor do we know any fpecimen that has been exhibited of its eminent advantages in mathemati- cal difculfions. Should it prove more fertile in geome- trical exprelhons of highly compounded or complicated quantities or relations, we fliould think it a mighty ac- quifition ; being fully convinced that thefe afford to the memory or imagination an obje£l (we may call it a fen- fible pidture) which it can contemplate and remember with incomparably greater clearnefs and fteadinefs than any algebraical formula. , We need only appeal to the geometrical expreflions of many fluents, which are to be feen in Newton's lunar theory, in the phyfical trafts of Dr Matthew Stewart, and others .who have {hewn a partiality for this method. It would be very prefumptuous, however, for us to fay, that the accurate geometer and metaphyficlan may Calendar not derive great advantages from profecuting the very j{ ingenious and recondite ipcculations of Mr Glenie, in ' j his doftrine of univerfal comparifon. CALENDAR, in chronology. See (Encycl.) Ka- LENDAR ; and Revolution, n° 1S4. CALIPPIC PERIOD, in chronology, a period of 76 years, cv'ntinually recurring ; at every repetition of which, it was fuppofed by its inventor Calippus, an A- thenian ailronomer, that the mean and new full moons would always return to the fame day and hour. About a century before, the golden number, or cy- cle of 19 years, had been invented by Meton ; which Calippus finding to contain 19 of Nabonaffar's year, 4 days, and \\\, to avoid fraftions he quadrupled it, and io produced his period of 76 years, or 4 times 19 ; after which he fuppoied all the lunations, &c. would re- gularly return to the fame hour. But neither is this exaft, as it brings them too late by a whole day in 225 years. CALLAO, as it is called by its inhabitants, but more generally known to Europeans under the name of Campello, is a fmall ifland, which was vifited by fome of Lord Macartney's fuite on their voyage to Ch';ia. In confequence of that vifit, we have the following de« fcription of it in Sir George Staunton's Account of the Embafly. " It lies oppofite to, and about eight miles to the eaftward of, the mouth of a confiderable river on the coaft of Cochin-china, on the banks of which is fituated the town of Fai-foo, a place of fome note, not far from the harbour of Turon. The bearing of the higheft peak of Callao from this harbour is about fouth eaft, diftance thirty miles. The extreme points of the ifland lie in latitude i 1;° J3', and i 1;" 57' nortli ; the greatell Icnnrth is from north-weft to fouth-eail, and is fomewhat about five miles, and the mean breadth two miles. The only inhabited part is on the fouth-weft coaft, on a flip of ground riling gently to the eaft, and contained be- tween the bottom of a femilunar bay and the mountains on each fide of it. Thofe mountains, at a diftance, ap- pear as if they formed two diftinft iflands. The fouth- ern mountain is the higheft, and is about 1500 feet. The lower grounds contain about 200 acres. This fmall but enchanting fpot is beautifully diverfified with neat houfes, temples, clumps of trees, fmall hillocks fwelling from the plain, and richly decorated with flirubbery and trees of varioi'S kinds ; among which the elegant arecn, rifing like a Corinthian column, is emi- nently confpicuous. A rill of clear water, oozing from the mountains, is contrived to be carried along the up- per ridges of the v:de, from whence it is occafionally conveyed through fluices, for the purpofe of watering the rice grounds, and appeared, though then in the dry fca- fon, fully iufficient for every jiurpofe for which it could be wanted. " The houfes, in general, were clean and decent ; a few were built with ftone, and covered with tiles. One, probably the manfion of the chief perlon of the ifland, was enclofed by a ftone wall, and the appoach to it was through a gateway between two ftone pillars. The houfe was divided into a number of apartments, of which the arrangement did not feeni to want cither tafte or convenience. This building ftood at the head of the principal village, which confifted of about thirty habitations C A L [ >5 Callao. habitations built of wood, chiefly the bamboo. Behind •—v^~ the village, and on the fide of the hill, was a cave, ac- ceflible only by one way, through an irregular range of rocks. Within the cave, but near its mouth, was a fmall temple, commanding a view of the whole vale. Several other temples were difperfed over the plain, all of which were open in front, with a colonnade before them of round wooden pillars, painted red and varnilh- ed. The number of houfes on the iiland fcarctly ex- ceeded fixty. Behind every houfe, not immediately in the principal village, were enclofures of fugar-cancs, to- bacco, and other vegetables, growing in great luxuri- ance. The mountains were covered with verdure, and feemed well calculated for rearing goats, of wiiich the jlland produced a few. " Befide the principal bay, there were feveral fandy inlets, with fmall patches of levc) ground behind them. Boats might eafily land in any of thefe inlets ; but a communication between them by land appeared to be exceedingly difficult, if not entirely prevented, by the ileep and rugged ridges which feparated them from each other. On this account very fiight works, and an e- ftablifliment of a few men only, would be requifite for the defence of the idand, a great part of its coaft being impregnably fortitied by nature. The depth of water in the bay and road was fufficient for (hips of any bur- den, and there was perfeft ihelter from every wind ex- cept the fouth-weft, to which quarter it was dired^ly open. The (hort diftance, however, from the conti- nent in that direftion would always prevent the fea from rifing high, though it might not be fufficiently near to break the force of the wind." The inhabitants of this idand are fo exceedingly fhy and afraid of ftrangers, that upon the approach of the Englifh veffel, they all, except a very few, retired on boai-d their galleys. When the Britifli landed, therefore, they found the doors of all the houfes open, with feveral domeftic animals feeding before them, but neither man, woman, nor child within. After fome time, however, a perfon was perceived lurking among the neighbour- ing trees, who, finding he was obferved, came forward iffith reluftance and evident marks of fear. While he was yet at fome diftance, he fell upon his knees, and touched the ground with his forehead feveral limes. On approaching to him, it was noticed that the firft joint ct every one of his fingers and toes was wanting, and as if twilled off by violence : it was poflible that he might have thus been treated byway of punilhment for fome crime, and that he was confidered as the fitted perfon to be expofcd to the fuppofed danger of watch- ing the movements of the ftrangers coming afliore. In a little time fome others, hidden in the thickets, find- ing that no mifchief was fuffered by the firft, ventured out. None of them could underftand the Chinefe inter- preter ; and net being able to read or write, there was no converfing with them by the medium of the Chinefe charafters. _ Recourfe was had to hieroglyphics, and lude figures were drawn of the articles which were pro- pofed to be purchafed ; and this method fucceeded to- lerably well ; poultry and fruits were brought for fale, for which high prices were given,, purpofely to conci- liate the good will of thofe iflanders. The few that were found grew foon familiar ; and one old man pref- fingly invited the ftrangers to his houfe, fituated upon an eminence, at a little diftance. On arriving there, I 1 CAM he introduced them to his wife, an old woman, who, after recovering from her aftonilhmcnt at the fight of figures fu different from thofe (he had ever been aecuf- tomed to behold, laid, in a ne.it manner, before them fome fruits, fugar, cakes, and water. On departing from the houfe, tliij decent and hol'pitable couple made figns to teftity their defire of feeing ihem again." The poflVlTion of this iiland would b^ of fuch im- portance to any European nation who wifhed to trade fecurely wltli Tungquin and Coch in chis.a, that it is faid the French had formerly fc'me thoughts of purcha- ling it. Sir George Staunton, hoivever, li of opinion, that the want of (hclterin the fouth-well monfoon would render it of little value, v.ithout a further fettlement near it upon the main land of Cochin-china : and he thinks, that if a folld eftablifliment there could be pro- ducfive of advantage to any European nation, it would necefiarily be fo to Great Britain ; becaufe, befide the opening which it would make for the fale of Britifti manufaftures among the people of the country, the Bri- tifli pofTcfiions in Kindoftan would be fure of a very conliderable demand for tlieir produftions. CAMEL, in navigation, is a machine which has been defcribed with fufficient accuracy in the Encyclo- pvEdia ; but the following account of its invention, given by ProfeiTor Beckmann, is perhaps not unworthy of a place in this Supplement. " In the Zuydei-Zee, oppofite to the mouth of the river Y, about fix miles from the city of Amfterdam, there are two fand banks, between which is z palfage called the Pampus, which is fufficiently deep for fmall fhips, but not for fuch as are large or heavy laden. In 1672 the Dutch contrived, however, to carry their nu- merous fleet through this paflage, by means of large empty chefts faftencd to the bottom of each fliip ; and this contrivance gave rife to the invention of the camtl." In the Encyelopa:dia Britannica its invention is given to the famous De Wit ; in the Germ:m Cyclopaedia to Meyer a Dutch engineer of very confidcrable eminence; but the Dutch writers, almnft unaiiiniouily, afcribe the invention of the camel to a citi/en of Amfterdam, who calls himfelf Meeuves Meindertfoon Bakker. " Some make the year of the invention to have been 16S8, and others 1690. Much has been faid of the utility of this invention ; but however beneficial it may be, we have reafon to fuppofe that fuch heavy vefTcls as fliips of war cannot be railed up, in fo violent a manner, without fuf- taining injury. A fure proof of this is the well known circumftance mentioned by Mufchenbroek ( InlrodnS'w ad Philnfopb. Nalur.J, that the ports of a Ihip which had been railed by the camel could not afterv\ards be fhut clofcly." CAMELEON, one of the conilellations of the fouthern hemifphere, near the fouth pole, and invifiblc in our latitude. There are 10 liars marked in this con- ftellation in Sharp's catalogue. CAMELOPARDALUS, a new conftellation of the northern hemifphere, formed by Hevelius, confift- ing of 32 ftars, firft obferved by him. It is fituated between Cepheus, Caffiopeia, Perfeus, the Two Bears, and Draco; and it contains 58 ftars in the Britifti ca- talogue. CAMELLIA, in botany (fee EncycL), is a plant which the Chinefe call Cha-iuha, or flower of tea, on account of the refemblance of the one to the other, and becaufe GAM [ 152 ] CAM 0.'.m|.!'ell. hecaufe its petals are fometimes mixed among the teas ' v-~— to increnfe tlicir fragrance. Sir George Staunton, who calls it Cc.infiiia Sefanqua, faw it flonrilhing on the fides and very high tops of moinitaius, where the foil con- filled of little mare than fragments of (lone, crumbled in- to a fort of coarfe earth by the joint aftion of the fun and rain. It yields, he fays, a nut, from which is exprtlfed an ifculent o::, equal to tiie bell which conies from Flo- rence. On this account, it is cultivated in vafl abun- dance ; and is particularly valuable from the facility of itr. culture in fit nations fit for little elfe. CAMPiyLLL (George, D. D.), fo juftly admired for his metaphy Ileal acutenefs and various erudition, was, in I 7 19, born at Aberdeen, where his father, the reve- rend Colin Campbell, was one of the minifters of the cftabliflied church. He was educated in his native city ; and, after paffirg through the ufual courfe of acade- mical learning, he lludicd divinity under the Rev. J. ■CJialmers, profeflbr of divinity in Marifehal College. — He was, in 1749, an unfuccefsful candidate for the thurch of Fordown, though his competitor Mr For- bes was a man of very flender abilities, and fuppofed to he attached to the conftitution and liturgy of the church of England. It might indeed be that attachment which contributed principally to procure him the living in pre- ference to Mr Campbell. The living of Fordown is in the gift of the crown ; and it has generally been a rule with his majetty's mi- uillers, to give fuch livings, when they become vacant, 10 thofe candidates who are favoured by the majority of land-owners in the parilh. At the era of 1745, the land-owners in feme of the northern and middle coun- lies of Scotland were more generally attached to the conllitutiou of the church of England than to that of their own eftabliihment ; and fuch was certainly the caie in the parifli of Fordown. But whatever was the caufe of Mr Campbell's failure, he failed by a very fmall number, and was not long without an eftabliihment. In 1750, he was prefented, by Sir Thomas Burnet of Leys, to the living of Ban- chary Ternan, on the Dee, about twenty miles weft from Aberdeen. From this he was tranilated, or, as the Scotch ecclefiattical phrafe is, tranj'porled to Aber- deen in 1756, and nominated one ot the city minifters, iiY the room of Mr John Biffet deceafed, a puritan of the old fchool, whole ftriftnefs and peculiarities are yet lemembered by many in that place. In 1759, oil the deceafe of principal pollock, he was chofen principal of the Marilchal college, and fucceeded to the divinity chair in 1771, on Dr Alexander Ge- rard being tranflated to the profefforlliip of divinity in King's college. Before his fettling in Aberdeen, he stianied Mils Grace Farquhavfon, daughter of Mr Far- quharfon of Whitehoule, by whom he had no ifl'ue. This amiable woman died about a year before him. They were an eminent pattern of conjugal affeftion. From this time he enjoyed a remarkable fliare of good health and Iplrits. He had, all his life, a rooted ■averfion to medicine. He got tiie better of every ail- ment by a total and rigorous abltlnence Irom all kind of fuftenanee whatever ; and it was not till lie was attacked by an alarming illnefs, about two years before his death, that he was ptrfuaded by his friends to call in medical iiid. What nature could do, (he had all along performed -\vcll ; but her day was over, and fomethiug of art be- came neceflary. Then, for the firft time, he owned Campbell the utility of medical men, and declared his recantation ~^~v~~' of the very mean opinion he had formerly entertained of them and their art. A few months before his death, he religned his offices of principal, profefi'or of divinity, and one oi the city minifters, and was in all fucceeded by Dr W. L. Brown, late of Utrecht, a man of dif- tinguillied abilities. Dr Campbell retained all his fa- culties entire to the laft, and died on the 6th of April 1796, in the 77th year of his age. His charadler has been fo juftly drawn by his luccefTor, that we fhall give it to our readers in his words, adding only a circum- ftance or two, which we have reafon to think will con- tribute to endear his memory to every liberal and en- lightened mind. " Dr Campbell, as a public teacher, was long ad- mired for the clearne's and copioulncfs with which he illullrated the great doftrines and precepts of religion, and the ftrength and energy with which he enforced them. Intimately perfuaded of the truth and infinite conlequence of what relevation teaches, he was ftrong- ly delirous of carrying theiame conviction to the minds of his hearers, and delivered his difcourfes with that zeal which flows from ftrong impreffions, and that power of perfualion which is the refult of fincerity of heart, combined with clearnefs of underllanding. He was fatisfied, that the more the pure diftates of the' gofpel were ftudied, the more they would approve themfelves to the mind, and bring forth, in the affec- tions and condudl, all the peaceable fruits of righteouf- nefs. The unadulterated dictates of Chriftianity, he was, therefore, only lludious to recommend and in- culcate, and knew perfectly to difcriminate them from the inventions and traditions of men. His chief ftudy ever was, to direft belief to the great objefts of praftice ; and, without thefe, he viewed the moll orthodox pro- feflion as " a founding brafs, and a tinkling cymbal." But, befides the charadler of a preacher of righteouf- nefs, he had alfo that of a teacher of the fcience of di- vinity to fullaln. How admirably he difcfiarged this duty, and with what effeCl he conveyed the foundeft and moft profitable inftruClion to the minds of his fcho- lars, let thofe declare who are now in various congre- gations of this country, communicating to their fellow Chriftians the fruits of their ftudies under fo able and judicious a teacher. Dilcarding all attachment to hu- man fyftems, merely confidered as fuch, he tied his faith to the Word of God alone, poffefted the happieft ta- lent in inveftigating its meaning, and communicated to his hearers the refult of his own inquiries, with a pre- cifion and perfpicuity which brought light out of ob- fcurity, iiud rendered clear and fimple what appeared intricate and perplexed. He expofed, without referve, the corruptions which ignorance, cratt, and hypocrify, had introduced into religion, and applied his talent for ridicule to the bell of all purpofes, to hold up to con- tempt the abfurdities with which the pureft and fub- limell truths had been loaded. " Placed at the head of a public feminary of learn- ing, he felt all the importance of fuch a fituation, and uniformly directed his influence to public utility. His enlarged and enlightened mind juftly appreciated the extenfive confequence of the education of youth. He anticipated all the eft'etts refulting to the great commu- nity of mankind, from numbers of young men iffuing, ir\ CAM [ Campliell. in regular fucceflion, from the univerfity over wliich he "■■"v— prcfidcd, and occupying the different departments of facial life. " His benevolent heart delighted to reprefent to it- felf the ftudents under his diredlion ufefully and ho- nourably difcharging the refpeftive duties of their dif- ferent profeffions ; and fome of them, perhaps, filling the mod dillinguillied ftations of civil fociety. With thefe profpeds before him, he conilantly diredted his public conduA to their attainment. He never fuffered his judgment to be warped by prejudice or partiality, or his heart to be feduced by paffion or private intereit. Thofe mean and ignoble motives by which many are aftuated in the difcharge of important trulls, approach- ed not his mind. A certain honourable pride, if pride it may be called, diffufed an uniform dignity over the whole of his behaviour. He felt the man degraded by the perverfion of public charafter. His underftand- ing alfo clearly fhewed him even perfonal advantage at- tached to fuch principles and praftice, as he adopted from a fenfe of obligation, and thofe elevated concep- tions of real worth which were fo congenial to his foul. He faw, he experienced, efteem, refpeft, and influence, following in the train of integrity and beneficence ; but contempt, difgrace, averfion,and complete infignificance, clofely linked to corruption and felfifhuefs. Little minds are feduced and overpowered by felfilh confiderations, becaufe they have not the capacity to look beyond the prefcnt advantage, and to extend to the mifery that ftands on the other fide of it. The fame circumftance that betrays the perverfity of their hearts, alfo evinces the weaknefs of their judgments. " His reputation as a writer is as extenfive as the prefent intercourfe of letters ; not confined to his own country, but fpread through every civilized nation. In his literary purfuits, he aimed not, as is very often the cafe, with men of diftinguiflied literary abilities, merely at eftabliihing his own celebrity, or increafing his for- tune ; but had chiefly at heart the defence of the great caufe of Religion, or tlie elucidation of her dilates. " At an early period he entered the lifts as a cham- pion for Chriftianity againll one of its acuteft oppo- nents. He not only triumphantly refuted his argu- ments, but even conciliated his refpeft by the handfome and dexterous manner in which his defence was conduc- ed. While he refuted the infidel, he fpared the man, and exhibited the uncommon fpedlacle of a polemical ■writer poireiTmg all the moderation of a Chriftian. But while he defended Chriftianity againft its enemies, he was defnous of contributing his endeavours to increafe, among its profefTors, the knowledge of the facred wri- tings. Accordingly, in the latter part of his life, he favoured the world with a work, the fruit of copious erudition, of unwearied application, for almoft thirty years, and of a clear and comprehenfive judgment. We have only to regret, that the other writings of the New Teftament have not been elucidated by the fame pen that tranflated the Gofpels. Nor were his literary merits confined to theology, and the ftudies more im- mediately connected with it. Philofophy, and the fine arts, are alfo indebted to his genius and labours ; and in him the polite fcholar was eminently joined to the deep and liberal divine. " Pohtica! principles will always be much affefled by general charafter. This was alfo the cafe with Dr SuprL. Vol. I, Part 1. 153 ] CAM Campbell. In politics, he maintained that moderation r.implicU. which is the furcft criterion of truth and reftltude, and '^ — ^^— ' was equally diftant from thofe extremes into which men are fo apt to run on great political queftlons. He che- nflied that patriotifm which confifts in wKhing, and en- deavouring to promote the greateft happinefs of his country, and is always fubordinatc to univerfal benevo- lence. Firmly attached to the Britini conftitutlon, he was anmiated with that genuine love of liberty which it infpires and invigorates. He was equally averfe to defpotifm and to popular anarchy ; the two evils into which political parties are fo frequently hurried, to the dcftruftion of all that is valuable in government. Par. ty-fplrit, of whatever defcription, he coniidered'as ha^ ving an unhappy tendency to pervert, to the moft per- nicious purpofes, the beft principles of the human miiid, and to clothe the moft iniquitous aCions with the moft fpecious appearances. Although tenacious of thofe fen- timents, whether in religion or politics, which he was convinced to be rational and juft, he never fuffered mere difference of opinion to impair his good-will to obftruft his good offices, or to cloud the cheerful'nefs of converfation. His own converfation was enlivened by a vein of the moft agreable pleafantry." So far was he from being influenced by jealoufy, or any portion of that corporation-fpirit which fometimes incites men of undoubted abilities to detraft from the merit of every writer who fills not a ftation as confpi- cuous as their own, that he was loud in his praifes of thofe, whom men of meaner minds would have looked upon with difguft, as upon prefumptuous rivals. This generofity was fully experienced by the writer of the article Miracle, in the Encyclopaedia Britannica, who, though he had prefumed to treat the fubjed differently from Dr Campbell, received from him fuch a teflimony of approbation of what he had done, as he will hnrdly look for from any other man in fimilar circumftances. Among his other qualities, which fo much endeared him to all who had the honour of his acquaintance, Dr Campbell poffeffed an uncommon facility of palling from the graveft to the moft airy fubjeds, and from the live- heft to the graveft, without degrading the one or di- minifliing the pleafure of the other. The infirmities of age abated not the cheerfulnefs of his temper, nor did even the perfuafion of approaching diffolution impair his ferenity. We cannot conclude this fliort n" " Various treatifes have been publlfhed in different languages, on the manner of breeding theie birds, and many people have made it a trade, by which they have acquired coufiderable gain. It does no difcredit to the indullry of the Tyrolians, that they have carried it to the greateft extent. At Ymlt there is a company, who, after the breeding feafon is over, fend out perfons to different parts of Germany and Switzerland to purchafe birds from thofe who breed them. Each perfon brings with him commonly from three to four hundred, which are afterwards carried for fale, not only through every part of Germany, but alfo to England, Rufiia, and even Conftantinople. About fixteen hundred are brought every year to England ; where the dealers in them, not- withftandlng the confiderable expence they are at, and after carrying them about on their backs, perhaps a jS ] CAN hundred miles, fell them for five (hillings a piece. This trade, hitherto neglefted, is now carried on in Scliwartz- walde ; and at prefent there is a citizen at Gottingen ; who takes with him every year to England feveral ca- nary-birds and bulfinches ( loxia pyrrhuLi), with the pro- duce of which he puvchafes fuch fmall wares as he has oceafion for." — Profrffbr BccLmann's HiJIory of Inven- tions and Di/coz'criss. C.iiWARY-Seed. tiee Phalaris, Encycl. — ProfcfTor Beckmann doubts whether the plant which bears the canary-feed be i\\t phalaris of the aneients, becaufe that name feems to have been given by Pliny to more than one fpecies of grafs. He thinks it very probable, how- ever, that the plant, which the modern botanifts call phalaris, was firft brought from the Canary Illands to Spain, where it began to be cultivated, as well as in the fouth of France, as foon as canary-birds came into ge- neral efteem. At prefent it is cultivated in various places, and forms no inconfiderable branch of trade, particularly \n the ifland of Sicily, where it is called Scagliuola or Scaghiola. Were it not that the grains are not eafily freed from the hulks, this plant might be cul- tivated for the food of man, for its feeds yield a good kind of meal. The phalaris has by feveral writers been confounded with argol or the lichen rocolla of Linneus ; but they are very different plants. See Lichen Ro- colla in this Supplement. CANDLE, a thing fo univerfally known as to need no particular defcription. Its ufe, however, is fo great, that every information tending to its improvement mull, we (hould think, be acceptable to our readers. Of the common method of making candles, whether of wax or of tallow, a fufficient account has been given in the En- cyclopaedia ; but candles of every kind are far from be- ing yet brought to that degree of pcrfcdlion of which they feem fufceptible. Thus, for example, the light of a candle, which is fo exceedingly brilliant when firft fnuffed, is very fpeedily dlminilhed to one half, and is ufually not more than one-fifth or one-fixth, before the uneafinefs of the eye induces us to fnuff it. Hence it follows, that if candles could be made fo as not to re- quire fnuffing, the average quantity of light afforded by the fame quantity of combutlible matter would be more than doubled. It may likewife be worthy of inquiry, fince the coft and duration of candles are eafily afcer- tainable, whether more or lefs light is obtained at the fame expence during a given time, by burning a number of fmall candles inltead of one of greater thicknefs. To determine this laft point, a method mull be found of meafuring the comparative intenfities of I'glit, for which fee Photometer in this Supplement. With refpeft to the defideratum firll mentioned, we have fome very ingenious obfervations and well-contrived ex- periments by Mr Nicholfon, in the fecond number of his valuable Journal, which we (hall here infert nearly in the words of their author. In every procefs of combuftion the free accefs of air is of the utmoft confequence. When a candle has a very (lender wick, the flame is fmall and of a brilliant white colour ; if the wick be large, the combuftion is lefs perfeft, and the flame brown ; and a wick (till lar- ger, not only exhibits a brown flame, but the lower in- ternal part appears dark, and is occupied by a portion of volatlhzed matter, which does not become ignited till it has afcended towards the point. When the wick is either CAN [ 159 ] CAN '!!«• either very large or very long, part of this matter occalionally brought into its vicinity by the vtrorkman. ^~~^ efcapes combuftion, and fliews itfelf in the form of coal But for the ufual piir}5ofes of illumination, it cannot be or fmoke. The fame things take place in the burning fuppofed that a perfoii can attend to fupply the com- of a lamp; but when the wick of a lamp is once ad- bulliblc matter. Confiderable dilTiculties arifc in the julled as to its length, the flame continues nearly in the projett for affording this gradual fupply as it may be fame ftate for a much longer time than the flame of a wanted. A cylindrical piece of tallow was inferted in- candle. to a metallic tube, the upper aperture of which was " Upon comparing a candle with a lamp (fays Mr partly clofed by a ring, and tiic central part occupied Nicholfon), two very remarkable particulars are imme- by a metallic piece nearly refembling tluit part of the diately feen. In the firft place, the tallow itfelf, which common lamp which carries the wiek. In this appara- remains in the unnifed Hate, affords a cup or cavity to tus the piece lalt defcribed was intended to anfwcr the hold that portion of melted tallow which is ready to fame pnrpofe, and was provided with a fhort wick. flow into the lighted part of the wick. In the fecond The cylinder of tallow was fupported beneath in fuch a place, the combuftion, inftead of being confined, as in manner that the metallic tube and other part of this the lamp, to a certain determinate portion of the fibrous lamp were left to reft with their whole weight upon matter, is carried, by a (low fuccelfion, through the the tallow at the ring or contraftion of the upper aper. vifhole length. Hence arifes the greater neceflity for ture. In this fituation the lamp was lighted. It burn- frequent fnuffing the candle ; and hence alfo the llatlon ed for fume time with a very bright clear flame, which, of the freezing point of the fat oil becomes of great wlien compared wllii that of a candle, poffeffed the ad- confeqnence. For it has been fhewn, that the bril- vantage of uniform intenfity, and was much fuperlor to liancy of the flime depends very m\ich on the diameter the ordinary flame of a lamp In Its colour, and the per- of the wick being as fmall as pofilble ; and this requi- tedf ablence of fmell. After fome minutes It began to fite will be moft attainable in candles tornied of a mate- decay, and very foon afterwards went out. Upon exa- rial that requires a higher degree of heat to fu(e It. minatlon, It was found that the metallic piece which The wick of a tallow candle muft be made thicker in carried the wick had fufed a infiicient quantity of tal- proportion to the greater fufibility of the matclal, low for the fupply during the combuftion ; that part of which would otherwife melt the fides of the cup, and this tallow had flowed beneath the ring, and to other run over in (beams. The flame will therefore be yel- remote parts of the apparatus, beyond the influence of low, fmoky, and obfcure, excepting for a fhort time the flame ; in confequence of which, the tube and the immediately after fnuflang. Tallow melts at the yad cylinder of tallow were faftened together, and the ex- . degree of Fahrenheit's thermometer ; fpcrmaceti at the peftcd progreffion of fupply prevented. It feems pro- 133d degree; the fatty matter formed of flefli, after bable that. In every lamp for burning confiftejit oils, the long immerfion in water, melts at 127 degrees; the material ought to be fo difpofed that it mav dfifcend to pela of the Chinefe at 145 degrees; bees-wax at 142 the flame upon the principle of the fountain refervolr. degrees ; and bleached wax at 15J degrees. Two of I fhall not here ftate tlie obftacles which prefent them- thefe materials are well known in the fabrication of can- felves in the profpeft of this coaftruftion, but ftiall dif- dles. Wax in particular does not aflord fo brilliant a mifs the fubjecf by remarking, that a contrivance of this flame as tallow; but, on account of its lefs furibilltv, nature would be of the g.rcatcft >)ublic utility. the wick can be made fmailer, which not only affords " The wick of a candle being furrounded by the the advantage of a clear perfect flame, but from its flexi- flame, Is nearly In the fituation of a body expofed to blllty It is difpofed to turn on one fide, and come in deftruftive diftlUation in a clofe veffel. After lofing its contaft with the external air, which completely burns volatile products, the carbonaceous refidue retains its Ti- the extremity of the wick to white afhes, and thus per- guic, until, by the defcent of the (hme, the external Jorms the office of fnufling. We fee therefore that the air can have accefs to its upper extvemity. But, in this important object to fociety of rendering tallow candles cafe, the requlfite combuftion, wh'ch might fnuff It, Is equal to thofe of wax, does not at all ilepend on the not effefted : for the portion of oil emitted by the combuftlbillty of the refpeftlve materials, but upon a long wick is not only too large to be perfeftly burned, mechanical advantage in the cup, which is afforded by but alfo carries off much- of the heat of the flame while the inferior degree of fufibility in the wax ; and that, it affumes the elaftlc ftate. By this dimlnilhed com- to obtain this valuable objed, one of the followii;g ef- buftlon and Increafed efflux of half-dccompofed oil, a fefts muft be produced: Either the tallow mult be portion of coal or foot is depolited on the upper part of burned in a lamp, to avoid the gradual progreffion of the wick, which gradually accumulates, and at length the flame along the wick ; or fomenieans muft be de- affumes the appearance of a fungus. The candle does Cr.n!!e. \ vlfed to enable the candle to fnuff itfelf, as the wax candle does ; or, laftly, the tallow itfelf muft be render- ed lefs fufible by fome chemical procefs. I have no great reafon to boaft of fuccefs in the endeavour to ef- feft thefe ; but my hope is, that the fatfs and obferva- tlons here prefented may confiderably abridge the la- bour of others in the fame purfuit. "The makers of thermometers and other fmall arti- cles with the blow-pipe and lamp, give the preference to tallow inftead of oil, bccaufe its combuftion is more complete, and does not blacken the glafs. In this ope not then give more than one-tenth of the light emitted in Its beft ftate. Hence it is that a candle of tallow cannot fpontancoufly fnuff itfelf. It was not probable that the addition of a fubftancc containing vital air or oxygen would fupply that principle at the preclfe pe- riod of time required ; but as experiment is the teft of every probability of this nature, 1 foaked a wick of cotton in a folution of nitre, then dried It, and made a candle. When this came to be lighted, nothing re- markable happened for a fliort time ; at the expiration of which a decrepitation followed at the lower extremi- ration the heat of the lamp melts the tallow which is ty of the flame, which completely divided the wick where CAN [ 1 Can.l'.e. where the blackened part commences. The whole of —^r—- tJie niattf r In combulllon tliereforc fell off, and the can- dle was of courfc inftantly cxtinguifhed. Whether this would have happened in all proportions of the fait or conllruitions of the candle, I did not try, becatife the fmell of azot was fufficlently ftrong and unpleafant to forb!,->" eall ; and in la- titude, the former 5^ 58' 30", the latter 5^49'fouth. They Avere vifited by fome of the perfons attending L,oid Macartney on his embafly to China; and are thus defcribed by Sir George Staunton. " At a little dlilance they might be miftaken for the remains of old caftles, mouldering into heaps of ruins, with tall trees already growing upon the tops ; but at a nearer view, they betrayed evident marks of a volca- nic origin. Explofions from fubterraneous fires, pro- duce, for the moft part, hills of a regular fhape, and ter- minating in truncated cones ; but when from a fub- aqneous volcano eruptions are thrown up above the furface of the fea, the materials, falling back into the water, are more irregularly dlfperfed, and generally leave the fides of the new creation naked and mifhapen, as in the inllance of Amsterdam, and of thofe fmaller fpots called, from fome refemblance in lliape, the Cap and Button. " In the Cap were found two caverns, running ho- rizontally into the fide of the rock ; and in thefe were a number of thofe birds ncfts fo much prized by the Chi- nefe epicures. They feeraed to be compofed of fine fi- laments cemented together by a tranfparent vifcous mat- ter, not unlike what is left by the foam of the fea up- on ftones alternately covered by the tide, or thofe gela- tinous animal fubftances found floating on every coaft. The nefts adhere to each other, and to the fides of the cavern, moftly in rows, without any break or interrup- tion. The birds that build thefe nefts are fmall grey fwallows, with ■bellies of a dirty white. They were flying about in confiderable numbers; but they were fo fmall, and their flight fo quick, that they efcaped the fhot fired at them. The fame nefts are fald alfo to be found in deep cavern;;, at the foot of the higheft moun- tains in the middle of Java, and at a dlilance from the fea, from which the birds, it is thought, derive no ma- terials, either for their food or the conftrudllon of their nefts ; as it does not appear probable they Ihould fly, in fearch of either, over the interm'ediate mountains, which are very high, or againft the boifterous winds prevailing thereabouts. Tliey feed on infefts, which they find hovering over ftagnated pools between the mountains, and for catching which their wide opening beaks are particularly adapted. They prepare their nefts from the bell remnants of their food. Their greateft enemy is the kite, who often intercepts them in their pall'age to and from the caverns, which are gene- rally furrounded with rocks of grey limellone or white marble. The nefts are placed in horizontal rows at different depths, from 50 to 500 feet. The colour and value of the nefts depend on the quantity and quality of the infefts caught, and perhaps alfo on the fituation where they are built. Their value is chiefly determined by the uniform finenefs and delicacy of their texture ; thofe that are white and tranfparent being moft elleem- ed, and fetching often in China their weight in filver. Thefe Cap, CAP [ dp. Tlicfe nefts are a confiderable objeft of traffic among •'-v—'~- t),e Javanefe, and many are employed in it from their infancy. The birds having fpent near two months in preparing their nefts, lay each two eggs, which are hatched in about fifteen days. When the young birds become fledged, it is thought time to feize upon their nefts, which is done regularly thrice a-year, and is ef- fected by means of ladders of bamboo and reeds, by which the people defccnd into the cavern ; but when it is very deep, rope ladders are preferred. This operation is attended with much danger ; and feveral break their necks in the attempt. The inhabitants of the moun- tains generally employed in it begin always by facri- ficing a buffalo ; which cullom is conftantly obferved by the Javanefe on the eve of every extraordinary en- terprife. They alfo pronounce iome prayers, anoint themfelves with fweet fcented oil, and fmoke the en- trance of the cavern with gum-benjamin. Near fome of thofe caverns a tutelar goddefs is worfhipped, whofe pried burns incenfe, and lays his protefling hands on every perfon preparing to deicend into the cavern. A flambeau is carefully prepared at the fame time, with a gum which exudes from a tree growing in the vicinity, and is not eafily extingulihed by fixed air or fubterra- reous vapours. The fwallow which builds thofe nefts js defcribed as not having its tail feathers marked with 63 ] CAR white i'pots, which is a charafter attributed to it by Linnjeus ; and it is poflible that there arc two fpecies or varieties of the fwallow, whofe nefts are alike va- luable." See BiRDS-Nefs, Encycl. CAPE OF Good Hope. See Good Hope, both in Encycl. and this Supplement. CAPITAL of a Bastion, is an imaginary line dividing any work into two equal and fimilar parts ; or a line drawn from the angle (■? the polygon to the point of the baition, or from the point of the baftion to the middle of the gorge. CAPRA, or tlie Shegoat, a name given to the ftar Capella, on the left ftioulder of Auriga, and fome- times to the conftcllation Capricorn. Some again re- prefent Capra as a conftellation in tlie northern hemif- phere,'confifting of three itars, comprifed between tiie 45th and 55th degree of latitude. — The poets fable her to be Amalthea's goat, which fuckled Jupiter in his infancy. CAPUT Draconis, or Dragon's Head, a name given by fome to a fixed ftar of the firft magnitude, in the head of the conftellation Draco. CARBON. See Chemistry in this SuppUmenI, Part I. Chap. 11. Seft. iii. C.\RP. See Cyprinus, both in the Encycl. and in this Supplement. CARPENTRY, (efinitior. n impor- nt brdnch niechaiu- 1 kieucc ' I 'HE art of framing timber for the purpofes of archi- -*■ tedm-e, machinery, and, in general, for all confi- derable ftruftures. It is not intended in this article to give a full account of carpentry as a mechanical art, or to defcribe the va- rious ways of executing its diff^erent works, fuited to the variety of materials employed, the procefles which muft be followed for faftiioning and framing them for our purpofes, and the tools which muft be ufed, and the manner in which they muft be handled : This would be an occupation for volumes ; and though of great im- portance, muft be entirely omitted here. Our only aim at preftnt will be to deduce, from the principles and laws of mechanics, and the knowledge which experience and judicious inferences from it have given us concern- ing the ftrength of timber, in relation to the ftrain laid on it, fuch maxims of conftruftion as will unite econo- my with ftrength and efficacy. This objeft is to be attained by a knowledge, ift, of the ftrength of our materials, and of the abfolute ftrain that is to be laid on them ; 2dly, of the modifications of this ftrain, by the place and direftion in which it is txerted, and the changes that can be made by a proper difpofition of the parts of our ftrufture; and, jdly, ha- ving difpofed every piece in fuch a manner as to derive the uttnoft advantage from its relative ftrength, we muft know how to form the joints and other connexions in fuch a manner as to fecure the advantages derived from this difpofition. This is, evidently, a branch of meclianical fcience, which makes carpentry a liberal art, conltitutes part of the learning of the ENGiNEtR, and diltingiiilhcs him from the workman. Its importance in all times and ftates of dvil focitty is inanifeft and great. In the pre- fent condition of thefe kingdoms, railed, by the adlive ingenuity and energy of our couyptrymen, to a pitch of profperity and influence unequalled in the hiftory of the world, a condition which confifts chiefly in the fu- periority of our manufactures, attained by prodigious multiplication of engines of every defcription, and for every fpecies of labour, the Science (io to term it) of carpentry is of immenfe confequence. We regret therefore exceedingly, that none of our celebrated ar- tifts have done honour to themfelves and their country, by digefting into a body of confecutive doftrines the refults of their great experience, fo as to forni a fyftem from which their pupils might derive the (irft principles of their education. The many volumes called Com- plete Instructors, Manuals, Jewels, &c. take a much humbler flight, and content themfelves with in- ftruifting the mere workman, or fometimes give the ma- fter-builder a few approved forms of roofs and other framings, with the, rules for drawing them on paper; and from thence forming the working draughts which niuil; guide the faw and the chiftel of the workman. Hardly anv of them ofter any thing that can be called a prin- ciple, applicable to many particular cafes, with the rules , for this adaptation. We are indebted for the greateft Prioc'pally part of our knowledge of this fubjeci to the labours of ■a'fe'Tfd to literary men, chiefly foreigners, who have publiflicd jn 'o eijintrs^ the memoirs of the learned academies diflertations on ledreof this different parts of what may be termed the fcience &/fiibjc>5l, carpentry. It is finguiar that the members of the Royal Society of London, and even ot that ellabllftied and fiip- portcd by the patriotifin ot thefe days for the encou- ragement of the arts, have contributed fo little to the public inftrnftion in this refpeCf. We obferve of late foine beginnings of this kind, fueJi as the laft part of X 2 Nichollon's 164 C A R P E Nicliolfoii's Carpenters and Joiners Assistant, publillud by J. Tavior, Holboin, 1 797. And it is with plcafure that we can fay, that we were told by the editor, that this work was prompted in a great meafure by what has been dclivcTed in the Encycloptedia Britan- n'ua ill the articles Rook and Strengih of Matenah. It abounds more in important and new obfervatioiis than any book of the kind that we arc acquainted with. We agai'! call on fnch as have given a fcientlfic attention to this fnbjciS, and pray that tiiey would render a merito- rious fervice to their country by inijiarting the refiilt of their relearches. The very limited nature of this work does not allow us to treat the fubjeCf in detail ; and we mull confine our obfcrvanons to the fundamental and 4 leading propofitions. Theoq-, "Ylxt theory (fo to term it) of carpentry is founded louiidcd on . j-n- ii .• r u • 1 r • _ what ""^ ililtuict portions 01 mechanical Icience, name- ly, a knowledge of the ftrains to which framings of timber are expoied, aMi a knowledge of their relative ftrength. We fhall therefore attempt to bring into one point of view the propofitions of mechanical icience that are more immediately applicable to the art of carpentry, and are to be found in various articles of our work, particularly Roof and Strrngth of Materials. From thefe propofitions we hope to deduce fuch principles as fhall enable an attentive reader to comprehend diilindly what is to be aimed at in framing timber, and how to attain this objeft with certainty : and we fhall illuf- trate and confirm our principles by examples of pieces of carpentry which are acknowledged to be excellent 5 in their kind. Compofi- The moft important propofition of general mechanics folution of carpenter is that wnich exhibits the conipohtion forces and refolution of forces ; and we beg our praftical rea- ders to endeavour to form very diftinft conceptions of it, and to make it very familiar to their mind. When accommodated to their chief purpofes, it may be thus expreffed : I. If a body, or anv part of a body, be at once pref- PlaleVin. Cgj jj, j},g ^^^ direaions AB, AC (fig. i ), and if the intenfity or force of tliofe preffures be in the pro- portion of thefe two lines, the body is affefted in the fame manner as if it were preffed by a fingle force a£l- ing in the dircftion AD, which is the diagonal of the parallelogram ABDC formed by the two lines, and whofe intenfity has the fame proportion to the intenfity of each of the other two that AD has to AB or AC. Such of our readers as havey?«,/;W the laws of mo- tion, know that this is fully demonltrated. We refer them to the article Mechanics, n° 5, &c. where it is treated at fome length. Such as wifli for a very accu- rate view of this propofition, will do well to read the demonftration given by D. Bernoulli, in the firil vo- lume of the Comment. Pelropol. and the improvement of this demonllration by D'Alembert in his Opufcles, and in the Comment. Taurinenf. The praftitioner in car- pentry will get more ufcful confidence in the dodlrinc, if he will Ihut his book, and verify the theoretical de- 6 monftrations by aftual experiments. They are remark. Bluftrated ably eafy and convincing. Therefore it is our requeft, mem''^"' ^^^ '^^^ artiil, who is not fo habitually acquainted with the fubjeft, do not proceed further till he has made it quite familiar to his thoughts. Nothing is fo condu- eive to this as the a6\ual experiment j and fince this on- N T R Y. ly requires the trifling expence of two fmall pulleys and a few yards of whipcord, we hope that none of our pradical readers will omit it : They will thank us for this injunftion. 2. Let the threads A it the example vliich brought this to our view is too limittd for ex- plaining llie efficacy whieh may be given to fuch con- ftrudions. We fliall therefore give a general propofi- tion, which will more diftinflly explain the procedure of nature, and enable us to trace the llrains as they are propagated through all the parts of the moll complica- ted framing, finally producing the exertion of its mott jg dillant points. General We prefume that the reader is now pretty well habi- propofi- tuated to the conception of the llrains as they are pro- *"'°' pagated along the lines joining the points of a frame, and we Hiall therefore employ a very limple figure. Let the llrong lines ACBD (fig. iv) reprefent a frame of carpentry. Suppole that it is pulled at the point A by a for?e aiiling in the diredion AE, but that it rells on a fixed point C, and that the other ex- treme point B is held. back by a power which refills in the direftion BF : It is required to determine the pro- portion of the llrains excited in its different parts, the proportion of the external prelTures at A and B, and the prelTurc which is produced on the obftacle or ful- crum C ? It Is evident that each of tbe external forces at A and B tend one way, or to one fide of the frame, and that each would caufe it to turn round C if the other did not prevent it; and that if, notwithftanding their ac- tion, it is turned neither way, tlie forces in atlual exer- tion are in equillbrio by the intervention of the frame. It is no lefs evident that thefe forces concur in prefTing the frame on the prop C. Therefore, if the piece CD were away, and if the joints C and D be perfeiflly flexi- ble, the pieces CA,CB would be turned round the prop C, and the pieces AD, DB would alfo turn with them, and the whole frame change its form. This ftiews, by the way, and we delirc it to be carefully kept in mind, that the firmnefs or HifFaefs of framing depends entirely on the triangles bounded by beams which are contained In it. An open quadrilateral may always change its fliape, the fides revolving round the angles. A quadrilateral may have an infinity of forms, without any change of Its fides, by merely puftiiiig two oppo- fite angles towards each other, or drawing them afun- der. But when the three fides of a triangle are deter- mined, its Ihape is alfo invariably determined ; and if two angles be held fall, the third cannot be moved. It is thus that, by inferting the bar CD, the figure be- comes unchangeable ; and any attempt to change It by applying a force to an angle A, immediately excites forces of attratlion or repulfion between the particles of the Huff which form its fides. Thus it happens, in the prefent Inllance, that a change of fliape is prevented i>y the bar CD, The power at A prefles its end againft N T R Y. the prop; and in doing this it puts (he bar AD on the ftretch, and alfo the bar DB. Their places might there- fore be fupplied by cords or metal wires. Hence it 13 evident that DC is comprell'ed, as is alfo AC : and, for the fame reafon, CB is alio in a Hate of compreflion ; for either A or B may be confidered as the point that is impelled or withheld. Therefore DA and DB arc llretched, and are refilling with attradlive forces. DC and CB are comprefled, and are refilling with repulfive forces. DB is alfo ailing with repulfive forces, being comprefled in like manner: and thus the fupport of the prop, combined with the firmnefs of DC, puts the frame ADBC into the condition of the two frames in fig. 8 and fig. 9. Therefore the external force at A is really in equillbrio witli an attracling force afting in the diredllon AD, and a repulfive force ai£ling In the diredtion AK. And fince all tlie connefting forces are mutual and equal, the point D Is pulled or drawn In the diredlion DA. The condition of the point B is fimi- lar to that of A, and D is alfo drawn in the direftion DB. Thus the point D, being urged by the forces in the direftlons DA and DB, prefles the beam DC on the prop, and the prop refills in the oppofite direftion. Therefore the line DC is the diagonal of the parallelo- gram, whofe fides have the proportion ot the forces which conneft D with A and B. This is the prin- ciple on which the reft of our inveftigation proceeds. We may take DC as the reprefentation and meafure of their joint effect. Therefore draw CH, CG, parallel to DA, DB. Draw HL, GO, parallel to CA, CB, cutting AE, BF in L and O, and cutting DA, DB In I and M. Complete the parallelograms ILKA, MONB. Then DG and AI are the equal and oppo- fite forces which conneft A and D ; for GD := CH, = AI. In like manner DH and BM are the forces which conneft D and B. The external force at A is In immediate equillbrio with the combined forces, connecling A with D and with C. AI is one of them : Therefore AK Is the other ; and AL is the compound force with which the external force at A is In immediate equilibrium. This external force is therelore equal and oppofite to AL. In like manner, the external force at B Is equal and oppofite to BO ; and AL is to BO as the exter- nal force at A to the external force at B. The prop C refifts with forces equal to thofe which are propagated to it from the points D, A, and C. Therefore It re- fills with forces CH, CG, equal and oppofite to DG, DH ; and it refills the comprefiions KA, NB, with- equal and oppofite forces C /■, C ti. Draw kl, n pa- rallel to AD, BD, and draw C /Q^, C P : It Is plain that /■ CH / is a parallelogram equal to KAIL, and that C / is equal to AL. In like mianner C is equal to BO. Now the forces Ci, CH, exerted by the prop, compofe the force C / ; and C n, CG compofe the force C 0. Thefe two forces C /, C are equal and parallel to AL and BO ; and therefore they are equal and op- pofite to the external forces acting at A and B. But they are (primitively) equal and oppofite to the pref- fures (or at leaft the compounds of the preflures) exert- ed on the prop, by the forces propagated to C from A, D, and B. Therefore the prelfures exerted on the prop are the fame as If the external forces were applied there in the fame direftions as they are applied to A and B. Now if we make CV, CZ equal to C / and C 0, and CARPENTRY. and complete tlie parallelogram CVYZ ; it is plain that blenis of liis art. He alfo learns, from this propofition, the force YC is in equilibrio with /C and oC. There- how to afcertain the ilraiiis that arc produced, without fore the preflures at A, C, and B, are fuch as would his intention, by pieces which he intended for other of- balance if applied to one point. fices, and which, by their tranfvcrfc aftion, put hij work Laftly, in order to determine their proportions, draw in hazard. In fliort, this propofition is liic key to the CS and CR perpendicular to DA and DB. Alfo draw fcience of his art. 169 A J, B /"perpendicular to CQjind CP ; and draw Cg, C /' perpendicular to AE, BF. The triangles CPR and BP/ are fimilar, having a common angle P, and a right angle at R andy". In like manner the triangl's CQS and AQjf are fi- milar. Alfo the triangles CHR, CGS are fimilar, by reafon of the equal angles at H and G, and the right angles at R and S. Hence we obtain the following analogies : Co : CP = 0« : PB, = CG : P3 CP : CR z= PB :/B CR: CS = ■ CH:CG CS : CQj= Ad: A(X_ CQj C / = AQj K /, = AQj CH. Therefore, by equality, Co : C/ = AJ:/B orBO:AL=r Cg.Cl. Tiiac is, the external forces are reciprocally propor- tional to the perpendiculars drawn from the prop on the lines of their diredlion (a). This propofition (fufliciently general for our pur- pofe) is fertile in confequences, and furnilhes many ufe- ful inilruftions to the artift. The drains LA, OB, CY, that are excited, occur, in many, we may lay in all, framings of carpentry, whether for edifices or engines, and are the fources of their efficacy. It is alio evident, 18 We would now counfel the artifl, afier he has made the tracing of the firains and thrulls through the v?.- rlous parts of a frame familiar to his mind, and even amufcd himfelf with fome complicated fancy framings, to read over with care the articles Stsfngth of Alole- r'uils and Roof in the Encyclnpitdia Bnlanmca. He will now conceive its doftrincs much more clearly than when he was coniidcring them as abltratt theories. I'he mutual a6lion of the woody fibres will now be eallly comprehended, and his confidence in the rcfults will be greatly increafed. There is a propofition (n° 19. in the article Roop) nerifion of which has been called in queftion by feveral very intelli- a nfj'uted gent perfors; and they fay that Bi'lldor has dcmonllra-!"''' '^'"^ ted, in his Science des Ingeniecrs, that abeam f-rfn- l"Jlni^^'" ly fixed at both ends is not twice as lliong as when fimply lying on the props, and that its llrength is in- creafed only in the proportion of 2 to ^ ; and they fup- port this determination by aliil-of experiments reci- ted by Belldor, which agree predftly with it. Belidor alfo fays that Pitot had the fame refult in his experi- ments. Thefe are refpedlable authorities : but IJeli. dor's reafoning is any thing but demonftratlon ; and his experiments are defcribed in fuch an imperfeil man- ner, that we cannot build much on them. It is not faid in what manner the battens were fecured at the that the doftrine of the tranfverfe fl:rength of timber is ends, any farther than that it was by cLei'itlets. If by this word is meant a trefsle, we cannot conceive how they were employed ; but we fee it foinetlmes nfed for a wedge or key. If the battens were wedged in the holes, their refinance to fraitiire inay be made whvt we pleafe : they may be loofe, and therefore refllt little more than when finiply laid on the props. They may See Strencth of Materials, be (and probably were) wedged very fall, and bruifed or crippled. Our propofi.tion mentioned diftlnflly the fecurity given to the ends of the beams. They were mortifed into remote pofts. 0\xr precife meaning was, that they were fimply kept from rifing by thefe mortifes, but at full liberty to bend up between E and I, and between Y G contained in this propofition; for every piece of timber may be confidered as an affemblage of parts, conneftfd by forces which aft in the direftion ot the hues winch join the ftrained points on the matter which lies be- tween thofe points, and alfo aft on the rcl!: of the mat- ter, exciting thofe lateral forces which produce tiie in flexibility of the whole. Encycl. Thus it appears that this propofition contains the principles which direft the artiff to frame the mod powerful levers ; to fecure uprights by fiiores or bra- ces, or by ties and ropes ; to fecure fcafFoldings for the ereftion of fpires, and many other moft delicate pro- SupPL. Vol. I. Part I. ( \) The learned reader will perceive, that this analogy is precifely the fame with that of forces which are in equilibrio by the intervention of a lever. In faft, this whole frame of carpentry is nothing elfe than a built or framed lever in equilibrio. It is afting in the fame manner as a folid, which occupies the whole figure comprcf- fed in the frame, or as a body of any fize and fiiape whatever that will admit the three points of application A, C, and B. It is always in equilibrio in the cafe firft dated ; becaufe the prelTure produced at B by a force applied to A is always fuch as balances it. The reader may alfo perceive, in this propofition, the analyfis or tra- cing of thofe internal mechanical forces which are indifpenfably requifite for the funftions of a lever. The me- chanicians have been extremely puzzled to find a legitimate demonftratlon of the equilibrium of a lever ever fiiice the days of Archimedes. Mr Vince has the honour of firft demonftrating, moft ingenioufly, the principle aflu- med by Archimedes, but without fufficient ground, for his demonftratlon : but Mr Viuce's demonllration is on- ly a putting the mind into that perplexed ftate which makes it acknowledge the propofition, but without a clear perception of its truth. The difficulty has proceeded from the a'bftraft notion of a lever, conceivino- it as a mathematical line — inflexible, without reflcfting how it is inflexible — for the very fource of this indifpenfable quality furnifhes the mechanical conneftion between the remote preflures and the fulcrum ; and this fupplies the demonftratlon (without the lead difficulty) of the defperate cafe of a ftraight lever urged by parallel forces. See Rotation, n° 11. Encycl. xyo CARPENTRY. 15 The btd manner of framing purlins. G and K. Our afTeition was not made from theory alone (although we think the reafoiiiiig incontrovertible), but was agreeable to numerous experiments made in thofe precife circumftances. Had we mortifed the beams lirmly into two very ftout polls, which could not be drawn nearer to each other by bending, the beam would have borne a muc/j greater weight, as we have verified by experiment. We hope that the toUowhig mode of conceiving this cafe will remove all doubts. Let LM be a long beam (fig. 14.) divided into fix equal parts, in the points D, B, A, C, E. Let it be firmly fupported at L, B, C, M. Let it be cut thro'igh at A, and have compafs-joints at B -ind C. Let FB, GC be two equal uprights, refting on B and C, but without any connexion. Let AH be a fimilar and equal piece, to be occafionally applied at the feam A. Now let a thread or wire AGE be extended over the piece GC, and made fall at A, G, and E. Let the fame thing be done on the other fide of A. If a weight be now laid on at A, the wires AFD, AGE will be ftrained, and may be broken. In the inftant of fraflure we may fuppofe their flrains to be reprefented by A/ and Ag. Complete the parallelogram, and An is the magnitude of the weight. It is plain that nothing is concerned here but the cohefion of the wires ; for t!ie beam is fawed through at A, and its parts are perfeftly moveable round B and C. Inftead of this procefs apply the piece AH below A, and keep it there by ftraining the fame wire BHC over it. Now lay on a weight. It mull prets down the ends of BA and CA, and caufe the piece AH to drain the wire BHC. In the inftant of frafture of the fume wire, its refiftance H3 and H r mud be equal to Af and A^, and the weight h H which breaks them mult be equal to A a. Laftly, employ ail the three pieces FB, AH, GC, v.'ith the fame wire attached as before. There can be no doubt but that the weight which breaks nil the four wires muft be -zz a \-\- h, or twice A a. The reader cannot but fee that the wires perform the very fame office with the fibres of an entire beam LM held faft in the four holes D, B, C, and E, of fome up- right pods. In the experiments for verifying this, by breaking llender bars of ime deal, we get complete demonftration, by meafuring the curvatures produced in the parts of the beam thus held down, and comparing them with the curvature of a beam fimply laid on the props B and C: and there are many curious inferences to be made from thefe obfervations, but we have not room ior them in this place. We may obferve, by the way, that we learn from this cafe, that purlins are able to carry twice the load when notched into the rafters that they carry when mortifed into them, which is the mod ufual manner of framing them. So would the binding joids of floors ; but this would double the thicknefs of the flooring. But this method fhould be followed in every poflible cafe, fuch as bread fummers, lintels over feveral pillars, &c. Thefe fhould never be cut off and mortifed into the fides of every upright ; numberlefs cafes will occur which fhew the importance of the maxim. V/e muft here remark, that the proportion of the . fpdces BC and CM, or BC and LB, has a very fenfible effeiSt on the ilrength of the beam BC ; but we have not yet fatisfied our minds as *-o the rationak of this ef- fcft. It is undoubtedly connedled with the fcrpentinc form of the curve of the beam before frafture. This (hould be attended to in the condruftion of the fprings of carriages. Thefe are frequently fupported at a middle point (and it is an excellent practice), and there is a certain proportion which will give the eafieft motion to the body of the carriage. We alfo think that it is con- nected with that deviation from the bed theory obfer- vable in Buffon's experiments on various lengths of the fame fcantling. The fovce of the beams diminidied much more than in the inverfe proportion of their lengths. We have feen that it depends entirely on the pofitionTiiTare in of the pieces in refpedt of their points of ultimate fup- j;eneral bet- port, and of the direftiou of the external force which '^'' '^*n produces the drains, whether any particular piece is in ' a date of extenfion or of compreffion. The knowledge of this circumftance may greatly influence us in the choice of the cundrudtion. In many cafes we may fub- ftitute flender iron rods for mafTive beams, when the piece is to a£t the part of a tie. But we muft not in- vert this difpofition ; for when a piece of timber afts as a ftrut, and is in a Hate of compreffion, it is next to certain that it is not equally compreffible in its oppofite fides through the whole length of the piece, and that the compreffing force on the abutting joint is not act- ing in the mod equable manner all over the joint. A very trifling inequality in either of thefe circumdanccs (efpecially in the firft) will comprefs the beam more on one fide than on the other. This cannot be without the beam's bending, and becoming concave on that fide on *hich it is molt compretfed. When this happens, the frame is in danger of being crufhed, and foon going to ruin. It is therefore indifpenfably neceffary to make ufe of beams in all cafes where ftruts are required of contlderable length, rather than of metal rods of flender dimenhons, unlefs in fituat ions where we can elfetlually prevent their bending, as in trufiing a girder internally, where a caft iron ftrut may be firmly cafed in it, fo as not to bend in the Inialleft degree. \.\\ cafes where the preffures are enormous, as in the very oblique ftruts of a centre or arch frame, we muft be particularly cautious to do nothing which can facilitate the compreffion of either fide. No mortifcs fhould be cut near to one fide ; no lateral preffure, even the flightelt, fhould be allowed to touch it. We have feen a pillar of fir i 2 inches long and one inch in feftion, when loaded with three tons, fnap in an inftant when preffed on one fide by 16 pounds, while another bore 4 J- tons without hurt, becaufe it was inclofed (loofely) in a flout pipe of iron. In fuch cafes of enormous compreffion, it is of great importance that the compreffing force bear equally on the whole abutting furfaces. The German carpenters are accuftomed to put a plate of lead over the joint. This prevents, in fome meafure, the penetration of the end fibres. Mr Perronet, the celebrated French ar- chiteft, formed his abutments into arches of circles, the centre of which was the remote end of the ftrut. By this contrivance the unavoidable change of form of the triangle made no partial bearing of either angle of the abutment. This always has a tendency to fplinter off the heel of the beam where it preffes ftrongeft. It is a very judicious practice. When circumftances allow^it, we ftiould rather em- ploy CARPENTRY. ploy ties than ftriits for fecuiing a beam againft lateral itrains. When an upright pillar, fiich as a flag ftaff, a niaft, or the uprights of a very tall fcaflolding, are to he fliored up, the ilependciice is more e;;rtaiii on thofe braces that are ftretchcd by the (train than on thofe which are comprefled. The fcaffolding of the iron bridge near Su\iderlaiid had feme ties very judicioudy dilpofed, and others with lels judgment. We (liould proceed to confider the tianfverfe drains 8. Laftly, the tranfvcrfe drain on any feAion, occa- fioued by a force applied obliquely, is diminiflied in the proportion of the fine of the angle which the direftion of the force makes with the beam. Thus, if it be in- clined to it in an angle of thirty degrees, the ftrain is one half of the drain occafioned by the fame force a&- ing peipendictllarly. On the other hand, the relative strfngth of a beam, or its power in any particular fedbOn to rcfiil: J7I us they afledl the various parts of a frame of carpentry ; any tranfverfe ftrain, is proportional to the abfolute co- but we have very little to add to what has been faid al- hefion of the feftion direc\ly, to the diftance of its ready in the article Strength of Mii/triah (Encycl.), centre of eftort from the axis of frafture direitly, and and in the article Roof. What we (liall add fn this ar- to the diftance from the drained point inverfely. ticle will find a place in our occafional remarks on dif- Thus in a reftangular fcdtion of the beam, of which A fercnt works. It may, however, be of ufe to recal to is the breadth, rf the depth (that is, the dimenfion in the reader's memory the following propofitions. the diredlion of the draining force), meafured in inches, I. When a beam AB (fig. 15.) is firmly fixed at the and /"the number of pounds which one fquare inch will end A, and a draining force adls perpendicularly to its juft fupport without being torn afunder, we mud have conceruinK length at any point B, the drain occafioned at any fee- fXiXd', proportional to w X C B (fig. ly.) Or, the r lativtjjgjj q between B and A is proportional to CB, and fXbXd', multiplied by fome number m, depending on lrlfm"=' " may therefore be reprefentea by the produdl WxCB ; the nature of the timber, mud be equal to w X CB. feeneral theoicms beams. that is, by the produdl of the number of tons, pounds, &c. which mealure the draining force, and the number of feet, inches, &c. contained in CB. As the loads on a beam are eafily conceived, we ftiall fubftitute this for any other draining force 2. If the drain or load is uniformly diftributed along any part of the beam lying beyond C (that is, further from .A ), the drain at C is the fame as if the load were all collefted at the middle point of that part ; for that point is the centre of gravity of the load. 3. The ftrain on any fedlion D of a beam AB (fig. 16.) reding freely on two props A and B,- is ^ AD xDB /f o o IP I- "wX ^-— (lee Rqof, n° 19. and Strength of AB Materials, n" 92, &c. Encycl.) Therefiire, 4. The drain on the middle point, by a force applied there, is one fourth of the drain which the fame force would produce, if applied to one end of a beam of the fame length, having the other end fixed. 5. The-«jTain on any feftion C of a beam, reding on two props A and B, occafioned by a force applied per- pendicularly to another point D, is proportional to the reftangle of the exterior fegments, or is equal to ACxDB Or, in the cafe of the ftdlion C of fig. 16. that ii drained by the force lu applied at D, we mull have ^fUJ^ ^ AC XDB m Xfb d' = lu X . ,,; •^ AB Thus if the beam is of i (fee Strength of Ma- fi£ 9 Therefore we have wX AB Therefore The drain at C occafioned by the preffure on D, is the fame with the ftrain at D occafioned by the fame prelfure on C. 6. The ftrain on any fedlion D, occafioned by a load uniformly diffufed over any part EF, is the fame as if the two parts ED, DF of the load were colledled at their middle poin,ts e andf. Therefore The drain on any part D, occafioned by a load uni- formly diftributed over the whole beam, is one-half of the ftrain that is produced when the fame load is laid on at D ; and The ftrain on the middle point C, occafioned by a load uniformly diftributed over the whole beam, is the lame which half that load would produce if laid on at C. 7. A beam fupported at both ends on two props B and C (fig- 14.) will carry twice as much when the found oak, m is very nearly teriah, 11° 116. Encycl.) ACXCB = ^ ^— 7Cb — Hence we can tell the precife force tv which any fec- tion C can juft refift when that force is applied in any way whatever. For the above-mentioned formula give* iu 1=. ^ , for the cafe reprefented by ficr 1 r. But 9CB '^ / o J the cafe reprefented in fig. 16. having the ftraining force applied at D, gives the ftrain at C ( = w ) ■=. f 9ACXCB' Example. Let an oak beam, four inches fquare, red freely on the props A and B, feven feet apart, or 84. inches. What weight will it juft fupport at its middle point C, on the fuppofition that a fquare inch rod will juft carry 16,000 pounds, pulling it afunder ? m, r 1 , 160CO X 4 X 16 X 84, The rormula becomes iu z= 3 Z_ 86oifio:o 9X42X42 orw=: r-T — > = 5418 pounds. This is very 15070 near what was employed in Buffon's experiment, v.hich was 531 2. Had the ftraining force adted on a point D, halfway between C and B, the force lufRcient to break the beam . (^ ij u 16-00X4X16X84 o ^ !U at C would be = — i Z = 1C856 lbs. 9 X 42 X 2f Had the beam been found red fir, we muft have ta- ken y^ 10,000 nearly, and m nearly 8 ; for a)tl/0jgh fir be lefs cohefive than oak in the proportion of 5 to 8 nearly, it is lefs comprelfible, and its axis of fracture is therefore nearer to the concave fide. Having confidered at fufficient length the ftrains Of joints, of different kir.ds which arife from the form of the parts of a frame of carpentry, and the dircdtion of ends beyond the props are kept from rifing, as it will the externa! forces whicli adl on it, whether conlidercd carry when it reiis loofely on the props. as impelling or as fupporting its different parts, we muft y 2 now 172 CARPENTRY. now proceed to confider the means by which this form is to be fccured, and the conneflions by which thofe ftrains are excited and conimiinicateJ. The joinings practifcd in carpentry are almoft infi- nitely various, and eacli has advantages vvhlcti make it preferable in fonie circuinllances. Many varieties are employed merely to pleafe the eye. We do not con- cern ourfelves with theft : Nor fliall v.e conilder thofe which are only employed in conneftirg imall works, ;nid can never ai)pear on a grtnt fcale : yet even in fome of thefe, the fliiil of the carpenter may be difcovered by his choice ; for in all cafes it is wife to make every, even the fmallcfl, part of his work as ftrong as the materials will admit. He will be particnlarly attentive to the changes which will n^cefurily happen by the flirinking of timber as it dries, and will confider what dimenfions of his framings will be affefted by this, and what will not ; and will then difpofe the pieces which are lefs effential to the ftrength cf the whole, in fuch a manner that their tendency to fhrink iliall be in the fame direAion with the flirinking of the whole framing. If he do otherwife, the feams will widen, and parts will be fplit afunder. He will difpofe his boardings in fuch a man- ner as to contribute to the ftiffnefs of the whole, avoid- ing at the fame time the giving them pofitions which will produce lateral ftrains on trufs beams which bear great prefTures; recollecting, that although a imgle board has little force, yet many united have a great deal, and may frequently perform the office of very powerful flruts. Our limits confine us to the joinings which are moft eifential for connefting the parts of a fingle piece of a frame when it cannot be formed of one beam, either for want of the neceffary thickncfs or length ; and the joints for connefting the different fides of a trulTed J, frame. Of building Much ingenuity and contrivance has been heftowed up beams. q[, the manner of building up a great beam of many thickneifcs, and many fingular methods are praftlfed as great noftrums by different artlif s : but when we con- fider the manner in which the cohefion of the fibres performs its ofSce, we will clearly tee that the fimpleft are equally effetf ual with the moft refined, and that they are lefs apt to lead us into falfe notions of the ftrength of the afTemblage. _ .,^+ Thus, were it required to build up a beam for a Building up , ' . ,T - , . r a girder cr great lever or a girder, lo that it may act nearly as a lever. beam of the fame fize of one log — it may either be ^5 done by plain joggling, as in fig. 17. A, or by fcarfing. in ficr. 17. B or C. If it is to act as a lever, ha- Joggling io fcarfing. ving the gudgeon on the lower fide at C, we believe that moft artifis will prefer the form B and C ; at leaft this has been-the cafe with nine-tenths of thofe to whom we have propofcd the queftion. The beft informed on- ly hefitated ; but the ordinary artifts were all confident in its fuperiorlly ; and we found their views of the matter very coincident. They confider the upper piece as grafping the lower in its hooks ; and feveral imagined that, by driving the one very tight on the other, the beam would be ftronger than an entire log : but if we attend carefully to the Internal procedure in the loaded lever, we fliall find the upper one clearly the ftrongeft. If they are formed of equal logs, the upper one is thicker than the other by the depth of the jog- gling or fcarfing, which we ftippofc to be the fame in both ; confequently, if the cohefion of the fibres in the intervals Is able to bring the uppermoft filaments into full aAion, the form A is ftronger than B, In the {pro- portion- of the greater diftance of the upper filaments from the axis of the fratfure : this may be greater than the difference of the thicknefs, if the wood is very com- prefTible. If the gudgeon be in the middle, the effeft, both of the joggles and the feaifings, is confiderably diminilhed ; and if It is on the upper fide, the fcarf. ings atf in a very different way. In this fituation, if the loads on the arms are alfo applied to the upper fide, the joggled beam is ftill more fuperior to the fcarfed one. This will be beft undtrllood by refolvlng it in ima- gination into ;i truffed frame. But when a gudgeon is thus put on that fide of the lever which grows convex by the ftrain, it is ufual to conntdt it with the reft by a powerful ftrap, which embraces the beam, and caufes the oppofite point to become the refilling point. This greatly changes the internal aftions of the filaments, and, in fome meafure, brings it into the fame ftate as the firft, with the gudgeon below. Were it pofTible to have the gudgeon on the upper fide, and to bring the whole into adion without a ftrap, it would be the Ifrongeft of all ; becaufe, in general, the refiftance to compreffion is greater than to extenfion. In every fituation the joggled beam has the advantage ; and it is th* eafieft executed. We may frequently gain a confiderable acceflion of ftrength by this building up of a beam ; efpecially if the part which is ftretched by the ftrain be of oak, and the other part be fir. Fir being fo much fuperior to oak as a pillar (if Muffchenbroek's experiments may be confided in), and oak fo much preferable as a tie, this conftru6tion feems to unite both advantages. But we fhall fee much better methods of making powerful le- vers, girders, jfc. by truffing. Obferve that the efficacy of both methods depends entirely on the difiiculty of caufing the piece between the crofs joints to Aide along the timber to which it adheres. Therefore, if this be moderate, it is wrong to make the notches deep ; for as foon as they are fo deep that their ends have a force fuflicient to pufh the ilice along the line of junftion, nothing is gained by making them deeper; and this requires a greater ex- penditure of timber. Scarfings are frequently made oblique, as in fig. 18. but we imagine that this is a bad practice. It begins to yield at tlie point, where the wood is crippled and fplintered off, or at leaft bruifed out n little : as the preflure increafes, this part, by fqueezing broader, caufes the folid parts rife to a little upwards, and gives them fome tendency, not only to pufh their antagonifls along the bale, Lut even to tear them up a little. For fimi- lar reafons, we difapprove of the iavourite praftlce of many artifts, to make the angles of their fcarfings acute, as in fig. ip. This often caufes the two pieces to tear each other up. The abutments fhould always be per- pendicular to the direftions of the preffures. Left it fhould be forgotten in its proper place, we may extend this injunftion alfo to the abutments of different pieces of a frame, and recommend it to the artift even to at- tend to the (hrinking of the timbers by drying. When two timbers abut obliquely, the joint ftiould be moft full IVe nuift full at the obtufe angle of the end ; becaufe, by dryinj^', that angle grows more obtufo, and the beam would then be in danger of fplintering off at tlie acute angle. It IS evident that the nicell work is inditpenfably ntwcrlL'e necelfary in building up a beam. The parts mull abut [00 hard. ^^^ ^^^.j^ qjIj^.,- completely, and the i'mallcll play or void takes away the whole efficacy. It is ulual to give the butting joints a fmall taper to one fide of the beam, fo that they may require moderate blows of a maul to force them in, and the joints may be perfeiStly clote when the external furfaees are even on each fide of the beam. But we mull not exceed in the leall degree ; for a very taper wedge has great force ; and if we have driven the pieces together by very heavy blows, we leave the whole in a Hate of violent llrain, and the abutments are per- haps ready to fplinter off by a fmall addition of pref- fure. This !s like too fevere a proof for artillery; which, though not fuffitient to burft the pieces, has weakened them to fuch a degree, that the llrain of or- dinary fervice is fufficient to complete the fradlure. The tL-orkman is tempted to exceed in this, becaufe it fmooths off and conceals all uneven fcams ; but he mull be watched. It is not unufual to leave fome abutments open enough to admit a thin wedge reaching through the beam. Nor is this a bad pradtice, if the wedge is of materials which is nut comprclfed by the driving or the flrain of fervice. Iron would be preferable for this purpofe, and for the joggles, were it not that by its too great hardnefs it cripples the fibres of limber to fome diftanee. In confequence of this, it often happens that, in beams which are fubjefled to dcfultory and fudden ftrains (as in the levers of reciprocating engines), the joggles or wedges widen the holes, and work tlicmfelves loofe : Therefore flcilful engineers never admit them, and indeed as few bolts as poflilile, for the faine reafon : but when refining a fleady or dead pull, they are not foim- proper, and are frequently ufed. Beams are buiit up not only to incrcafe their dinien- Cons in the direftion of the llrain (which we have hi- therto called their depth), but alfo to increafe their breadth or the dimenfions perpendicular to the flrai CARPENTRY.' 173 Fig. 21. exhiWts anotlier method. The two halves »9 of the beam arc tabled info each other in the fame man ^^ ^^'^' ner as in fig. 17. It is plain that this will not be af.'""'^'"^ fefted by the unequal fwelling or fhrinking, becaufe this is inlenfible in tiie direftion of the fibres ; but when bent in tlie direction a 6, the beam is weaker than fig. 2C. bent in the diredion ef. Each half of fig. 20. has, in every part of its length, a tliicknefs greater than half the thicknefs of tl'.e beam. It is the c^jntrary in the alternate portions i;f the halves of fig. 21. AVhen one of them is bent in the diredion AB, it is plain that it drags the other with it by means of the crofs butments of its tables, and there can be no longitudinal Hiding. But unlefs the work is accurately executed, and each hollow completely filled up by the table of the other piece, there"will be a lateral Hide along the crofs joints fufHcient to compenfate for the curvature ; and this will hinder the one from comprcinng or llretching the other in conformity to this curvature. jo 'I he impcrfediou of this method is fo obvious, that Its imper. it has feldom been pradf ifed : but it has been combined '•'^"'"' with the other, as is reprefentcd in fig. 22. where the beams are divided along the middle, and the tables in each half are alternate, and alternate alfo with the tables of the other lialf. Thus i, 3, 4, are prominent, and 5, 2, 6, are depreffed. Tiiis conilrudion evidently puts a flop to both fides, and obliges every part of both pieces to move together, a b and c d fhow fec- tions of the built-up beam correfponding to AB and CD. No more is intended in this praftfce by any intelli- gent artitt, than the caufing the two pieces to ad to- gether in all their parts, although the llrains may be un- equally dillributcd on them. Thus, in a built-up gir- der, the binding joints are frequently monifed into very- different parts of the two fides. But many feem to aim at making the beam flronger than if it were of one piece ; and this inconfiderate projeft has given rife to many ivhimfical modes of tabling and fcarfing, which we need not regard. ,j The praftice in the Britifli dock-yards is fomewhat Brieifli We fometimes double the breadth of a girder which different from any of thefe methods. The pieces are ""=''""' 5 ij thought too weak for its load, and where we mnfl not iucreafe the thicknefs of the flooring. The mafl of J. a great fhip of war muft be made bigger athwartfhip, as iuildingof well as fore and aft. This is one of the nicefl pro- nalb. bleras of the art ; and profeffinn-.d men are by no means agreed iu their opinions about it. We do not prefume to decide ; and fhall content ourfclves with exhibiting the different methods. The niofl obvious and natural method is that (liewn in fig. 20. It is plain that (independent ot the con. nedion of crofs bolts, which are ufed in them all when the beams are fquare) the piece C cannot bend in the diredion of the plane of the figure without bending the piece D along with it. This method is much ufed in the French navy ; but it is undoubtedly imperfed. Hardly any two great trees are of equal quality, and fwcU and fhrink alike. If C fhrinks more than I), the feather of C becomes loofe in the groove wtoiight in D to receive it ; and when the beam bends, the parts can ilide on each other like the plates of a coach fpring ; and if the bending is in the diredion e f, there is no- thing to hinder this Aiding but the bolls, which foon work, themfelves loofe in the bolt-holes. as lethod ed in ihc encli 3vy, tabled as in fig 22. but the tables are not llun paralle. lopipeds, but thin prifms. The two ouHvard joints or vifible feams are flraight lines, and the table n" I. rifes gradually to its grcatefl thicknefs in the axis. In like niauQCf, the hollow 5 for receiving the oppofite table, finks gradually from the edge to its greatell depth in the axis. Fig. 23. reprefents a fedion of a round piece of timber built up iri this way, where the full line . EFGH is the fedion correfponding to AB of fig. 22. and the dotted line EGFH is the fedion correfpond- ing to CD. This conftrudion, by making the external feani flraight, leaves no lodgment for water, and looks much fairer to the eye : but it appears to us that it does not give fuch firm hold when the maft is bent in the diredfion EH. The exterior parts are moll flretched and moll comprefled by this bending ; but there is hardly any abutment in the exterior parts of thefe tables. In the very axis, where the abutment is the firmetl, there is little or no difference of extenfion and compreffion. But this conftrudion has an advantage, which we imagine much more than compenfates for thefe imper- fe<9;ions5. J 74 C A R P E /e(?Sif!n=!, at leafl in tVic particular cafe of a round maft: it will draw togcthc-r hy hooping incomparably better than any of the others. If the cavity be made fome- what too (hallow for the prominence of the tables, and if this be done uniformly along the whole length, it will make 3 fomewhat open feam ; and this opening can be regulated with the utmoil exaftnefs from end to end by the plane. The heart of thofe vaft trunks is very fenfibly fofter than the exterior circles : There- lore, when the whole is hooped, and the huops hard driven, and at confidcrable inter\'als between each fpell — we are confident that all may be coinprelTed till the feam difappears ; and then the whole makes one piece, ii:iich rtronger than if it were an original log of that lize; bccaufe the middle has become, by compreffion, as folid as the crull, which was naturally firmer, and refifted farther compreffion. We verified this beyond a doubt, by hooping a built ftick of a timber which has thi^ in- equality of firmnefs in a remarkable degree, and it was nearly twice as ftrong as another of the fame fize. Our mattmakers are not without their fancies and whims ; and the manner in which our mails and yards are generally built up, is not near fo fimple as fig. Z2.: but it confdts of the fame effential parts, afting in the very fame manner, and derives all its efficacy from the ,1 principles which are here employed. rAM^nded This conftrudtion is particularly fuifed to the fitua- -with ptcu- tjpfi anjl ofBce of a (hip's maft. It has no bolts ; or, ■^ ^'^^ " at leafl, none of any magnitude, or that make very im- portant parts of its conftruftion. The m.oft violent f*rains perhaps that it is expofcd to, is that of twifting, when the lower yards are clofe braced up by the force of many men afting by a long lever. This form refifts a twill with peculiar energy : it is therefore an excel- lent method for building up a great (haft for a mill. The way in which they are ufually built up is by redu- cing a central log to a polygonal prifm, and then filling it up to the intended fize by planting pieces of timber along its fides, either fpiking them down, or cocking them into it by a feather, or joggling them by (lips of hard wood funk into the central log and into the (lips. A'. B. Joggles of elm are fometimes ufed in the middle of the laige tables of mafts ; and when funk into the firm wood near the furface, they muft contribute much to the llrength. But it is very neceflary to employ wood not much harder than the pine ; otherwife it will foon enlarge its bed, and become loofe ; /or the timber of thefe large trunks is very foft. The moft general reafon for piecing a beam is to in- creafe its length. This is frequently neceffary, in order to procure tie-beams for very wide roofs. Two pieces mull; be Icarfed together. — Numberlefs are the modes f/f doing this ; and almofl every mailer carpenter has his favourite nollrum. Some of them are very ingeni- ous : But here, as in other cafes, the moft fimple are ."■' commonly the ftrongeft. We do not imagine that any, nietho'.'is r>f t'' moft ingenious, is equally ftrong with a tie confift- fcarni^g. ing of two pi> ces of the fame fcantling laid over each other for a certain length, and firmly bolted together. We acknowledge that this will appear an artlefs and clumfy tie-beam ; but we only fay that it will be ftronger than any that is more artificially made up of the fame thicknefs of timber. This, we imagine, will appear fufficiently certain. The fimplcft and moft obvious fcarfing (after the N T R Y. one now mentioned) is that reprefented in fig. 24. n" t. and 2. If confidered mertlv as two pieces of wootj joined, it is plain that, as a tic, it has but half the ftrtngth of an entire piece, fuppofing that the bolls (which arc the only connedtions) are faft in their holes. N° 2. requires a bolt in the middle of the fcarf to give it that ftrength ; and, in every other part, is weaker on one iide or the other. But the bolts are very apt to bend by the violent ftrain, and require to be ilrengthened by uniting their ends by iron plates ; in which cafe it is no longer a wooden tie. The form of n° i. is better adapted to the ofRce of a pillar than n' 2. ; efpecially if its ends be formed in the manner tliewn in the elevation n^ 3, By the fally given to the ends, the (carf refifts an effort to bend it in that diredlion. Befides, the form of n' 7. is unfuitable for a poft ; becaufe the pieces, by fii- ding on each other by the prelTure, are apt to fplinter off the tongue which confines their extremitv. Fig. 25. and 26. exhibit the moft approved form of a fcarf, whether for a tie or for a poft. The key re» prefented in the middle is not eftentially neceiTary ; the two pieces might fimply meet fquare there. This form, without a key, needs go bolts (although they ftrength- cn it greatly) ; but, if worked very true and clofe, and with fquare abutments, will hold together, and will re- fift bending in any direflion. But the key is an inge- nious and a very great improvement, and will force the parts together with perfeft tightULfs. The fame pre- caution muft be obferved that we mentioned ori*ano- ther occafion, not to produce a conftant internal ftrain on the parts by ovei'driving the key. The form of fig. 25. is by far the beft; becaufe the triangle of 26. is much eafier fplintered o(f by the ftrain, or by the key, than the fquare wood of 25. It is far preferable for a poft, for the reafon given when fpeaking of fig. 24. n= 1. and n^ 2. Both may be formed with a fally at the ends equal to the breadth of the key. In this ftiape, fig. 25- is vaftly well fuited for joining the parts of the long corner ports of fpires and orher wooden towers. Fig. 25. n" 2 differs from n" 1. only by having three keys. The principle and the longitudinal ftrength are the fame. The long fcarf of n' 2. tightened by the three keys, enables it to refill a bending much better. None of thefe fcarfed tie-beams can have more than one-thiid of the ilrength of an entire piece, unlefs with the alTiftance of iron plates ; for if the key be made thinner than one-third, it has lefs than one-third of the fibres to pull by. We are confident, therefore, that when the heads of the bolts are conncfted by plates, the fimple form of fig. 24. n° I. is ftronger than thofe more ingenious fcarfings- It may be ilrengthened againft lateral bend- ing by a little tongue, or hy a fally ; but it cannot have both. The ftrongeft of all methods of piecing a tie-beam would be to fet the parts end to end, and grafp them between other pieces on each fide, as in fig. 27. This 34 is what the (hip-carpenter czlh fijhing a beam ; and is a Fi1''"g"* frequent pra&ice for occafional repairs. Mr Perronet *"'■ ufed it for the tie-beams or ftretchers, by which he con- nected the oppofite feet of a centre, which was yield- ing to its load, and had pufiied afide one of the piers above four inches. Six of thcle not only withilood a ftrain of i8co tons, but, by wedging behind them, he brought CARP Brought the feet of the trufs 2t inches nearer. The ftretchers were ^t] inches by 1 1 of found oak, and could have withllood three times that ttrain. Mr Perronet, fearing that the great lengtli of the bolts employtd to conncft the beams of tliefe ftretchers would expofe them to the rilk of bending, fcarfed the two fide pieces into the middle piece. The fcarfing was of the trian- gular kind ("Trail de Jupiter), and only an inch deep, each face being two feet long, and the bolt pafTed through clofe to the angle. In piecing the pump rods, and other wooden ftretch- ers of great engines, no dependence is had on fcarfing; and the engineer connects every thing by iron ftraps. We doubt the propriety of this, at leaft in cafes wliere the bulk of the wooden conneftion is not inconvenient. Thefe obfervations muil fuffice for the methods employ- ed for connecting the parts of a beam ; and we now proceed to confider what are more ufually called the 35 joints of a piece of carpentry. quare Where the beams ftand fquare with each other, and Jints, {|,j ftrainf are alfo fquare with the beams, and in the plane of the frame, the common mortife and tenon is the moil perfect junftion. A pin is generally put through both, in order to keep the pieces united, in oppofition to any force which tends to part them. Every carpenter knows how to bore the hole for this pin, fo that it (hall draw the tenon tight into the mor- tife, and caufe the fhoulder to butt clofe, and make neat work ; and he knows the rifle of tearing out the bit of the tenon beyond the pin, if he draw it too much. We may juft obferve, that fquare holes and pins are much preferable to round ones for this pur- pofe, bringing more of the wood into aftion, with lefs tendency to fplit it. The fhip carpenters have an in- gcnious method of making long wooden bolts, which do not pafs completely through, take a very faft hold, though not nicely fitted to their holes, which tliey mull 36 not be, left they fiiould be crippled in driving. They oitail (.3II Jt jQxtail ivtdgirg. They ftick into the point of ^ ■*' the bolt a very thin wedge of hard wood, fo as to pro- jeft a proper difta.ice ; when this reaches the bottom of the hole by driving the bolt, it fplits the end of it, and fquetzes it hard to the fide. This may be prac- tifed with advantage in carpentry. It the ends of the mortife are widened inwards, and a thin wedge be put into the end of the tenon, if will hzve the fame etfcft, and make the joint equal to a dovetail. But this rifcs the fplitting the piece beyond the fhoulder of the te- non, which would be unfightly. This may be avoided as follows : Let the tenon T, fig. 28. have two very thin wedges a and c ftuck in near its angles, projedling equally ; at a very fmall diftance within thefe, put in two ftiorter ones b, il, and more within thefe if nccef- fary. In driving this tenon, the wedges a and c will take firft, and fph't off a thin flice, which will eafily bend without breaking. The wedges b, d, will act next, and have a finiilar tffeft, and the others in fucr ceflion. The thickncfs of all the wedcres taken toee- ther muft be equal to the enlargement of the mortife toward the bottom. When the ftrain is traufvcrfe to the plane of the two fceams, the principles Inid dov^n in n" 85, 86. of the ar- ticle Strcsgih of Materials, will direft the aitift in placing his mortife. Thus the mortife in a girder for receiving the tenon of a binding joift of a floor ftiould ENTRY. 175 be as near the upper fide as poffible, becaufe the girder becomes concave on that fide by the ilrain. But as this cxpofes the tenon of the binding joill to the rifk of being torn off, we are obliged to mortife farther down. The form (fig. 29.) generally given to this joint is extremely judicious. The Hoping part a b gives a very firm fupport to the additional bearing e.d, with- out much weakening of the girder. This form flionld be copied in every cafe where the ftrain has a fimllar direftion. ,« The joint that moft of all demands the careful atten- Oblique tion of the artift, is that which conntdls the ends of "'^''"'^^'^'"^ beams, one of which pufhes the other very obliquely, ^'" "• putting it into a ftaie of extenfion. The moft iainiJiar inftance of this is the foot of a rafter preffing on the tie-beam, and thereby drawing it away from the other wall. When the direftion is very oblique (in which cafe the extending ftrain is the greateft), it is difficult to give the foot of the rafter luch a hold of the tie- beam as to bring many ot its fibres into the proper ac- tion. There would be little diificulty if we could al- low the end of the tie-beam to projeft to a fmall dif- tance beyond the foot of the rafter : but, indeed, the dimenfions which are given to tie-beams, for other rea- fons, are always fufficient to give enough of abutment when judicioufly employed. Unfortunately this joint is much expofed to failure by the effefts of the wea- ther. It is much expofed, and . frequently pcrifties by rot, or becomes fo ioft and friable that a very fmall force is fuificlent, either for pulling the filaments out of the tie-beam, or for crufiiing them together. We are therefore obliged to fecure it with particular attention, and to avail ourfelves of every circumllance of con- ftruftion. One is naturally difpofed to give the rafter a deep hold by a long tenon ; but it has been frequently ob- ierved in old roofs that fuch tenons break oft. Fre- quently they are oblcrved to tear up the wood that is - above them, and pulh their way through the end of the tie-beam. This, in all probability, arifes from the tail fagging of the roof, by the comprefllon of the rafters • and of the head of ihe king-poll, '['he head of the rat- ter defcends, the angle with the tic-beam i? diniiailhed by the rafter revolving round its ilcp in the tie-beam. By this motion the heel or inner angle of the rafter be- comes a fuicium to a very long and powerful lever much loaded. Tlie tenon is the other arm, very lliort, and being Hill frelh, it is therefore very powerful. It tiierc- fore forces up the wood that is above it, tCLiring it out from between the cheeks of the mortife, and theri pullics it along. Carpenters have therefore given up long te- nons, and giv^e to the toe of the tenon a (hape which abuts firmly, in the direftion of the thruftj on the folid . bottom of the mortife, which is will fuppoitcd on the under fide by the wall-plate. This form has the farther advantage of having no tendency to tear up the end of ' the mortife. This form is reprcfentcd in fig. ^o. The tenon has a fmall portion a b cut perpendicular to thc furfate of the tie-beam, and the reft be is peipeiidicular to the rafter. But if the tenon is not fufflciently ftr'ong (and it is rot fo llrong as the rafter, which is thought not to he ftronger than is neceffary), it will be crufaed, and then the rafter will fliade out along the furface of the bcsm. It ij therefore necelTary to Citll in the ;iffifta.ice of tlic vvlujle,- 176 C A R P E whole rafter. It is in tliis diftributioii of the Iliai.i among the various abutting parts that the varieties of joints and tlieir merits ehiefly conlilL It would be endlefs to defcribc every nollrum, and wc fliall only men- o tion a few that are moll gen;;rally approved of. Mofl ap. ihe aiin in fig. 31. is to make the abutments exaft- prored ly perpendicular to the thruils. It does this very pre- forms, cifely ; and the ftare which the tenon and the (houlder have of the whole may be what we pleafe, by the por- tion of the beam tint we notch down. If the wall-plate lie duly before the heel of the rafter, there is no rifk of ftraining the tie acrofs or breaking it, becaufe the thruft is made diredl to that point where the beam is fupport- ■ed. The aftion is the fame as again II the joggle on the head or toot of a king-poft. We have no doubt but that this is a very effectual joint. It is not, however, much praftifed. It is faid that the Hoping feam at the (houlder lodges water; but the great reafon feems to be a fecret notion that it weakens the tie-beam. If we conllder the diredlion in which it acts as a tie, we muft acknowledge that this form takes the bell method for bringing the whole of it into aclion. Fig. 32. exhibits a form that is more general, but certainly worfe. What part of the thruft that is not borne by the tenon afls obliquely on the joint of the flioulder, and gives the whole a tendency to rife up and ilide outward. The (lionlder joint is fometimes formed like the dot- ted line abctlefg of fig. 32. This is much more agreeable to the true principle, and would be a very perfeft method, were it not that the intervals hd and i/f are fo fliort that the little wooden triangles iv c/, def, will be cafily pufli:-d off their bales h d, df. Fig. 33. feems to have the moll general approbation. It is the joint recommended by Price (page 7.), and copied into all books ot carpentry as the true joint for a rafter foot. The vifible Ihoulder-joiut is flufli with the upper furface of the tie-beam. The angle of the tenon at the tie nearly bifedls the obtufe angle formed by the rafter and the beam, and is therefore fomewhat oblique to the thruft. The inner (houlder ar is nearly perpen- dicular to b d. The lower angle of the tenon is cut off horizontally as at e d. Fig. 34. is a feclion of the beam and rafter foot, (hewing the different Ihoulders. We do not perceive the peculiar merit of this joint. The effeft of the three oblique abutments ab, a c, e d, is undoubtedly to make the whole bear on the outer end of themortife, and there is no other part of the tie- beam that makes immediate refiftance. Its only advan- tage over a tenon extending in the direction of the thruft is, that it will not tear up the wood above it. Had the inner flioulder had the form e c i, having its face ic perpendicular, it would certainly have atted more powerfully in ftretching many filaments of the tie- beam, and would have had much lefs tendency to force out the end of the mortife. The little bit c i would have prevented the Aiding upwards along e c. At any rate, the joint a 3 being fludi with the beam, prevents any fcnfible abutment on the fhoulder ac. Fig. 33. n^ 2. is a Ampler, and in our opinion a pre- ferable, joint. We obferve it praftifed by the raoft eminent carpenters foi all oblique thruils ; but it furely employs lefs of the cohefion of the tie-beam than might be ufed without weakening 'it, at leatt when it is fup- ported on the other fide by the wall-plate. N T R Y. Fig. 33. no 3. is alfo much pra£lifcd by the firft car* penters. Fig. 35. is propofed by Mr Nicholfon (page 65.) zs preferable to fig. ^}. i\'' ^. becaufe the abutment of the inner part is better iupported. This is certainly the cafe; but it fuppofes the whole rafter to go to the bot- tom of the focket, and the beam to be thicker than the rafter. Some may think that this will weaken the beam too much, when it is no broader than the rafter is thick; in which cafe they think that it requires a deeper focket than Nicholion has given it. Perhaps the advantages of Nicholfon's conftruftion may be had by a joint like fig- 35- "'2-. , Whatever is the form of thefe butting joints, great Circum- care (hould be taken that all parts bear alike, and the dances to artift will attend to the magnitude of the different fur-*''^ attend- faces. In the general compreffion, the greater furfaces' "'' will be lefs compreffed, and the fmaller will therefore change moft. When all has fettled, every part (lioidd be equally clofe. Becaufe great logs are moved with difficulty, it is very troublefome to try the joint fre- quently to lee how the parts fit ; therefore we muft ex- peft lefs accuracy in the interior parts. This (hould make us prefer thofe joints whofe efficacy depends chief- ly on the vifible joint. It appears from all that we have faid on this fubjeft, that a very fmall part of the cohefion of the tie-beam is fufficient for withftanding the horizontal thruft of 'a roof, even though very low pitched. If therefore no other ufe is made of the tie-beam, one much flenderer may be ufed, and blocks may be firmly fixed to the ends, on which the rafters might abut, as they do on the joggles on the head and foot of a king-poll. Al- though a tie-beam has commonly floors or ceilings to carry, and fometimes the workfhops and ilore-rooms of a theatre, and therefore requires a great icantling, yet there frequently occur in machines and engines very ob- lique llretchers, which have no other ofirce, and are ge- nerally made of dimenfions quite inadequate to their fi- tuation, often containing ten times the neceffary quan- tity of timber. It is therefore of importance to afcer- tain the moft perfedl manner of executing fuch a joint. We have directed the attention to the principles that are really concerned in the effefrl. In all hazardous cafes, the carpenter calls in the affiftance of iron llraps; and tliey are frequently neceffary, even in roofs, not- withftanding this fuperabundant ilrength of tlietie-beam. But this is generally owing to bad conftruftion of the wooden joint, or to the failure of it by time. Straps will be confidered in their place. There needs but little to be faid of the joints at a ioggle worked out of folid timber ; they are not near fo difficult as the laft. When the fize of a log will al- low the joggle to receive the whole breadth of the a- butting brace, it ought certainly to be made with a fquare flioulder ; or, which is ftill better, an arch of a circle, having the other end of the brace for its centre. Indeed this in general will not fenfibly differ from a ftraight line perpendicular to the brace. By this circu- lar form, the fettling of the roof makes no change in the abutment ; but when there is not fufficient Ituff for this, we muft avoid bevel joints at the flioulders, becaufe thefe always tend to make the brace Aide off. The brace in fig. ^6. muft not be joined as at a, but as at i, ox foEie equivalent manner. Obferve the joints at the C A R P E the head of the main pofts of Drury Line theatre, fig. 40 D. itting When the very obh'que aftion of one fide of a frame iits. of carpentry docs not extend but coniprcfs the piece on Vv-hich it abuts (as in fig. 11.), there is no dilllcully in the joint. Indeed a joining is unnectfTary, and it ij enough that the pieces abut on each other; and we have only to take care that the mutual prelVure be equal- ly borne bv all the parts, and that it do not produce la- teral prelTilres, which may caufe one of the pieces to Aide on the buttir,'^ joint. Avery (light mortife and tenon is fufficient at the joggle of n king-pod with a rafter or llraining beam. It is bell, in general, to make the butting plain, bil'cfting the angle formed by the fides, or clfe perpendicular to one of the pieces. In iig. 36. n" z. where the llraining beam a h cannot flip away from the prcfiure, the joint a is preferable to h, or indeed to any uneven joint, which never fails to produce very unequal prefTures on the different parts, by which ^, fome are crippled, others are fpliiitered off, ic. iredliors When it is necefiary to employ iron llraps for llrength- r placing ening a joint, a confiderable attention is necefiary, that ■» '^"1 *• we may place them properly. The firft thing to be deter- mined is the direftion of the ilniin. This is learned by the obfervations in the beginning of this article. We mull then refolvethis ftrain into a drain parallel to each piece, and another perpendicular to it. Then the drap which is to be made fad to any of the pieces muil be fo fixed, that it fliall refid in the direiftion parallel to the piece. Frequently this cannot be done ; but we mud come as near to it as we can. In fuch cafes we mud fuppofe that the affemblage yields a little to the pref- fures which aft on it. We mud examine what change of fliape a fmall yielding will produce. We mud now fee how this will afieft. the iron drap which we have al- ready fnppofed attached to the joint in fome manner that we thought fultable. This fetthng will perhaps draw the pieces away from it, leaving it loofe and un- ferviceable (this frequently happens to the plates which are put to fecure the obtufe angles of butting timbers, when their bolts are at fome diftance from the angles, efpecially when thefe plates are laid on the infide of the angles) ; or it may caufe it to comprefs the pieces hard- er than before; in which cafe it is anfwering our inten- tion. But it may be producing crofs drains, which may break them ; or it may be crippling them. We can hardly give any general rules ; but the reader will do well to read what is written in n" 36. and 41. of the article Roof, Encycl. In n° 36. he will fee the nature of the drap or dirrup, by which the king-pod carries the tie-beam. The ilrap that we obferve mod gene- rally ill placed is that which connedls the foot of the rafter with the beam. It only binds down the rafter, but does not adl againd its horizontal thrud. It (hould be placed farther back on the beam, with a bolt through it, which will allow it to turn round. It Ihould em- brace the rafter almod horizontally near the foot, and (hould be notched fquare with the back of the rafter. Such a condrudlion is reprefented in fig. 37. By mo- \'ing round the eye-bolt, it follows the rafter, and can- not pinch and cripple it, which it always does in its or- dinary form. We are of opinion that draps which have eye-bolts in the very angles, and allow all motion round them, are of all the mod perfeft. A branched drap, fuch as may at once bind the king-poft and the two SuppL. Vol. I. Part I. N T R Y. 177 braces which butt on its foot, will be more ferviccable if it have a joint. When a roof warps, thofe branched draps frequently break the tenons, by affording a ful- crum in one of their bolts. Aii attentive and judicious artiil win confider how the beams will aft on fuch oc- cafiuns, and will avoid giving rife to thefc great drains by levers. — A fliilfiil carpenter never employs many draps, coufidering tliein as auxiliaries foreign to his art, and fubjeft to im])erfcftions in workmanlhip which he cannot difccrn nor amend. We mull refer the reader to Nicholfon's Carpi-nfir and Joiner's Assistant for a more particular account of the various forms of dirrups, fcrewed rods, and other iron work forcarrying tie-beams, &c. As for thofe that are neceflary for the turning joints of great engines conllrufted of timber, they make no part of the art of carpentry. 4* After having attempted to give a fydematic viewDnamplej of the principles of framinsf carpeniry, we fiiall con- f'f different elude, by g-iving- fome examples which will iilfldrate and'""^''' r \ r ■ 'I carpentry, confirm the foregoing principles. ^j Fig. 38. is the roof of the chapel of the Royal Hof-Roofof pital at Greenwich, condrufted by Mr S. Wyat Greenwich Scantling. AA, Is the tie-beam, 57 feet long, fpanning 51 feet clear - - - - 14 by 12 CC, Queen-pods .... oXi.'J D, Braces ..... pX7 E, Trufs beam .... 10X7 F, Straining piece .... 6X7 G, Principal rafters ... 10X7 H, A cambered beam for the platform . 9.7 B, An Iron dring, fupporting the tie-beam 2X2 The trufles are 7 feet apart, and the whole is covered with lead, the boarding being fupported by horizontal ledgers h, h, of 6 by 4 inches. This is a beautiful roof, and contains lefs timber than rood of its dimenfions. The parts are all difpoied with great judgment. Perhaps the iron rod is unneceffary ; but it adds great diffnefs to the whole. The iron llraps at the rafter feet would have had more eflfcft if not fo oblique. Thofe at the head of the polls are very effeftive. We may obferve, however, that the joints between the draining beam and its braces are not of the bed kind, and tend to bruife both the draining beam anti the trufs beam above it. Fig". 39. tlie roof of St Paul's, Covent Garden, con-st Taul's, drufted by Mr Waplhot in 1796. Covcht A A, Tie-beam fpanning 50 feet 2 inches 16.12 B, Queen-pod 9X8 C, Trufs beam 10X8 D, King-pod (14 at the joggle) . - 9X8 E, Brace »X74- FF, Principal brace (at bottom) - - 1oX8t HH, Principal rafter (at bottom) . IoXBt gg. Studs fupporting the rafter - . 8x8 This roof far excels the original one put up by Inigo Jones. One of its truffes contains 198 feet of timber. One of the old roof had 273, but had many inaftive timbers, and others ill difpofed. (A''. B. The figure which we gave of it in the article Roof, copied from Z Price, Garden. 178 45 Birming'- bam the- atre. C A R P E Price, IS very erroneous). The internal trufs FCF is admirably contrivtd for fupporting the exterior ratters, without any prefTure on the far projefling ends of the tie-beam. The former roof had bent them greatly, fo as to appear ungraceful. We think that the camber (fix inches) of the tie- beam is rather hurtful ; bccaufe, by fettling, the beam lengthens; and thlsmufl be accompanied by a confidrr- ahle finking of the roof. This will appear by calcula- tion. Fig. 40. the roof of Birmingham theatre, conflruft- ed by Mr Geo. Saunders. The fpan is 80 feet clear, and the truffes are 10 feet apart. N T R Y. A, Is an oak corbel B, Inner plate ... C, Wall plate D, Pole plate E, Beam .... F, Straining beam G, Oak king-poll (in the Ihaft) H, Oak queenpoft (in the Ihaft) I, Principal rafters K, Common ditto I., Principal braces M, Common ditto N, Purlins ... Q, Straiiiing^ fill 9X5 9X9 7x5 15X15 12X9 9x9 7X9 9X9 4X24 9 and 6X9 6X9 7X5 5iX9 This roof is a fine fpecimen of Britifh carpentry, and IE one of the boldeft and lighteft roofs in Europe. The ftraining fill Q_ gives a firm abutment to the principal braces, and the fpace between the pofts is 19I feet wide, affording roomy workfhips for the carpenters and other workmen conneftcd with a theatre. The con- trivance for taking double hold of the wall, which is very thin, is excellent. There is alfo added a beam (marked R), bolted down to the tie-beams. The in- tention of this was to prevent the total failure of fo bold a trufling, if any of the tie-beams (hould fail at the ^f end by rot. EruryLane Akin to this roof is fig. 41. the roof of Drury Lane theatre. theatre, 80 feet 3 inches in the clear, and the trufles 15 feet apart, conftrufted by Mr Edward Grey Saunders. A, Beams - - - - - 10 by 7 B, Rafters 7X7 C, King-poft* .... 12X7 D, Struts - - - - - 5X7 E, Purlins ..... 9X5 G, Pole plates - - - - ■ S^^S I, Common rafters .... 5X4 K, Tie-beam to the main trufs - - 15X12 L, Pofts to ditto .... 15X12 M, Principal braces to ditto - 14 and 12X12 N, Struts 8X12 P, Straining beams • - - -' 12X12 The main beams are truffed in the middle fpace with oak trufles 5 inches fquare. This was neceflary for its width of 32 feet, occupied by the carpenters, painters, &c. The great fpace between the truffes affords good ftore-rooms, drefiing-rooms, &c. It is probable that .this roof has not its equal in the world for lightnefs, ftiffnefs, and ftrength. The main trufs is fo judicioufly framed, that each of them will fafe- ly bear a load of near 300 tons ; fo it is not likely that 47 4? they will ever be quarter loaded. The divifion of the whole into three paits makes the exterior roofings very liglit. The ftrains are admirably kept from the walls, and the walls are even firmly bound together by the roof. They alfo take oft the dead weight from the main trufs one-third. The intelligent reader will perceive that all thefe roofs Remarks are on one principle, depending on a trufs of three pieces and a ftraight tie-beam. This is indeed the great principle of a trufs, and is a ftep beyond the roof with two ratters and a king poft. It admits of much greater variety of forms, and of greater extent. We may fee that even the middle part may be carried to any fpace, and yet be flat at top ; for the trufs beam may be fupported in the middle by an inverted king, poft (of timber, not iron), carried by iron or wooden ties from its extremities : And the fame ties may carry the horizontal tie-beam K ; for till K be torn afunder, or M, M, and P be crippled, nothing can fail. The roof of St Martin's church in the Fields is con. ftrufted on good principles, and every piece properly difpofed. But although its fpan does not exceed 40 feet from column to column, it contains more timber in a trufs than there is in one of Drury-Lane theatre. The roof of the chapel at Greenwich, that of St Paul's, Co- vent Garden, that of Birmingham, and that of Drury Lane theatres, form a ferles gradually more perfect. Such fpecimens afford excellent leffons to the artifts. We therefore account them a ufeful prefent to the pub- lic. There is a very ingenious projeft offered to the pub-Prfjei5l bj lie by Mr Nicholfon [Carpenter's Affijlant, p. 68.) He Mr Nictio propofcs Iron rods for king-pofts, queen-pofts, and all''"'' other fituations where beams perform the of&ce of ties. This is in profecutlon of the notions which wc publlfti- ed in the article Roof of the Encycl. (fee n"36, 37.) He receives the feet of the braces and ftruts in a focket very well conntfted with the foot of his iron king-poll; and he fecures the feet of his queen-pofts from being pufhcd inwards, by interpofing a ftraining fill. He does not even mortlfe the toot of his principal rafter in- to the end of the tie-beam, but fets it in a focket like a Ihoe, at the end of an iron bar, which is bolted into the tie-beam a good way back. All the parts arc formed and difpofed with the precifion of a perfon thoroughly acquainted with the fiibjetl; and we have not the fmall- eft doubt of the fnccefs of the projedt, and the complete fecurity and durability of his roofs, and we expect to fee many of them executed. We abound In Iron, but we muft fend abroad for building timber. Thls-is there, fore a valuable project ; at the fame time, however, let us not over-rate its value. Iron is but about 1 2 times ftronger than red fir, and is more than 1 2 times hea- vier ; nor is It cljeaper, weight for weight, or ftrength for ftrength. Our Illuftrations and examples have been chiefly taken from roofs, becaufe they 3re the moft familiar Inflances of the diiBcult problems of the art. We could have wlfhed for more room even on this fubjeft. The con- ftruclion of dome roofs has been (we think) miftaken, and the difficulty is much lefs than is imagined. We mean in refpefl of ftrength ; for we grant that the ob- liquity of the joints, and a general intricacy, increafes the trouble of workmanlhip exceedingly. Another op- portanity may perhaps occur for confidering this fubje(ft> Wooden (AH I'l; N I i;v n..vn. \ in ■'iQ-. J . Fig. 2. -^H riR-. 3. Tiff. 8 --.& Fie-. 6. --^.ra :=^_1 CAHPl'.XTRV Pi,ATK IX. Fie-. JO. U I.,«-.ri f^-ulr, I C-ARFJATin' 1-1 ^VIK X.. Fi„-. m. Kig-.TO. Fig-. 2Z. Kio-. ■.';). X° 2. tie-. v?l. Tie-. M. Fio- . 24 . V"! fi]^.24, v;^ Kio- ^.'J . Flr-'^J.V? ■-'• Fig". ?() [i.r I'VlU'EVfUV I'l.ATK XU i^li .1 CO I! CARFKXTRy in.ATt xi. Xi ii fig-. 33. IS^ 2. s.,^.^fe TU. 33. I Fie-.33.3S^°3 >^-r- rip-. 3 4. rig'. 30. T\'.- .3b J Tig. 36. te„/- ^. i rig-.35 x° :? Fig-. 3g:s[° ?. / "'t 49 'oodcn Uges. raming of rest lever C A R P E Wooden bridges form another clafs equally difficult and important ; but our limits arc alieady overjiafred, and will not admit them. The principle on which they fliould all be con(lru6ted, without exception, is that of a trufs. avoiding all lateral bearings on any of the tim- bers. In the application of this principle, we mud far- ther remark, that tlie angles of our truls thould be as acute as poflible ; therefore we fliould make it of as few and as long pieces as we can, taking care to prevent the bending of the trufs beams by bridles, which embrace them, but without prefling them to either lide. When the trufs confifts of many pieces, the angles are very ob- tufe ; and the thrufts increafe nearly in the duplicate proportion of the number of angles. The proper ma- xims will readily occur to the artift who confiders with attention the fpecimens of centres or coombs, which we (hall give in the article Centre. With refpcft to the frames of carpentry which occur engines and great machin&s, the varieties are fuch that it would require a volume to treat of them proper- ly. The principles are already laid down ; and if the reader be really interefted in the ftudy, he will engage in it with ferioufnefs, and cannot fail of being inftru«!v^« rafcabel II Caflli.i. CAS CASCABEL, the knob or button of metal behind the breech of a cannon, as a kind of handle by which to elevate and diredl the piece ; to which fome add the ' fillet and ogees as far as the bafe-ring. CASEMATE, or Cazemate, in fortification, a kind of vault or arch of ftone-work, in that part of the fiank of a baftion next the curtain ; ferving as a battery to defend the face of the oppofite baftion, and the moat or ditch. It is now feldom ufed, becaufe the batteries of the enemy are apt to bury the artillery of the cafemate in the ruins of the vault; befide, the great fmoke made by the difchacge of the cannon renders it intolerable to the men. So that, inflead of the ancient covered cafemates, later engineers have contrived open ones, only guarded by a parapet, &c. Casemate is alfo ufed for a well with feveral fubter- raneous branches, dug in the paffage of the baftion^ till the miner is heard at work, and air given to the mine. CASSINI (James), a celebrated French aftronomer, was born at Paris February 18. 1677, being the young, er fon of Johannes Dominicus CaHini, of whom fome account has been given in the Encych^tSa- CAS After his firfl ftudies in his father's houfe, in which it is not to be fuppofed that mathematics and aftronomy * would be neglefted, he was fent to ftudy philofophy at the Mazarine college, where the celebrated Varignon was then profeftor of mathematics. From the affiftance of this eminent young man Caflini profited fo well, that at 15 years of age hefupported a mathematical thefisvvith great honour. At the age of 1 7 he was admitted a mem- ber of the Academy of Sciences ; and the fame year he accompanied his father in a journey to Italy, where he aflifted him in the verification of the meridian at Bo- logna and other meafurenients. On liis return he per- formed fimilar operations in a journey into Holland, where he difcovered fome errors in the mealnre ot the earth by Snell, t!ie refult of which was communicated to the Academy in 1702. He made alfo a vifit to England in 1696, where he was made a member of the Iloyal Society. In 1712 he fucceeded Us father as aftronomer royal at the obfervatory of Paris. In 1717 he gave to the Academy his refearches on the diftance of the fixed ftars ; in which he fiiewcd that the whole annual orbit, of near 200 millions of milea diameter, is but as a point in comparifon of that diftance. The fame year he com- Z 2 municated Cadini. CAS [ i8 CalTini. municated alfo his difcoveries concerning the inch'nation •"—v^"' of the orbits of the fatelh'tes in general, and efpecially of thofe of Saturn's fatellites and ring. In 1725 he undertook to determine the caufe of the moon's hbra- tion, by which (he (hews fometimes a little to'.vards one fide, and fometimes a little on the other, of that half which is commonly behind or hid from our view. In 1732 an important qnellion in aflronomy exercifed the ingenuity of our author. His father had determi- ned, by his obfervation?, that the planet Venus revolved about her axis in the fpacc of 23 hours ; and M. Eian- chini had publiflied a work in 1729, in which he fettled the period of the fame revolution at 24 days 8 hours. IVom an examination of Bianchini's obfervations which were upon the fpots in Venus, he difcovered that he had intermitted his obfervations for the fpace of three hours, from which caufe he had probably miftaken new fpots for the old ones, and fo had been led into the mi- ftake. The probability is, that both had fallen into fome miftake, or that they had proceeded on very diffe- rent principles; for othervvife fuch different refults are wholly unaccountable. Dr Herlchel feems fatisfied that the period of the revolution is lefs than Bianchini has made ; but he does not fay what it is, or that it is not much greater than it was fuppofed by Caffini. Our author, after he had convifted Bianchini, as he thought, of error, determined the nature and quantity of the acceleration of the motion of Jupiter at half a fecond per year, and of that of the retardation of Saturn at two minutes per year ; that thefe quantities would go on increafing for 2000 years, and then would decreafe again. In 1740 he publifhed his Aftronomical Tables, and his Elements of Ailronomy ; very extenlive and ac- curate works. Although aftronomy was the principal objeft of our author's confideratlon, he did not confine himfelf nbfo- lutely to that branch, hut made occafional excurfions into other fields. We owe alfo to him, for example. Experiments on Eledlricity, or the Light produced by Bodies by Friftion ; Experiments on the Recoil of Fire- arms ; Refearches on the Rife of the Mercury in the Barometer at different Heights above the Level of the Sea; Refi.'Hions on the perfefting of Burning- glaffcs; and other Memoirs. The French Academy had properly judged, that one of its mod important objefts was the meafurement of the earth. In 1669 Picard meafured a little more than a degree of latitude to the north of Paris ; but as that extent appeared too fmall from which to conclude the whole circumference with fuflicient accuracy, it was re- folved to continue that meafure.-nent on the meridian of Paris to the north and the fouth, through the whole extent of the country. Accordingly, in 1683, the late M. de la Hire continued that on the north fide of Pa- ris, and the older Caffmi that on the fouth fide. The latter was alfilled in 17CO in the continuation of this operation by his fon our author. The fame work was farther continued by the fame academicians; and, finally, the part left unfinifhed by De la Hire in the north was finillied in 17 18 by our author, with the late Maraldi, and De la Hire the younger. Thefe operations produced a confiderable degree of precifion. It appeared alfo, from this meafured extent of fix degrees, that the degrees -.vere of different lengths in different parts of the meridian; and in fuch fort that o ] CAS our author concluded, in the volume publiihed for 1718, Cafiini. that they decreafed more and more towards the pole, ' - ■ v— and that therefore the figure of the earth was that of an oblong fphcroid, or having its axis longer than the equatorial diameter. He alfo meafured the perpendicu- lar to the fame meridian, and compared the meafured dif- tance with the differences of longitude as before deter- mined by the eclipfes of Jupiter's fatellites : whence he concluded that the length of the degrees of longitude was fmaller than it would be on a fphere, and that therefore again the figure of the earth was an oblong fpheroid, contrary to the determination of Newton by the theory of gravity. Though Ncivton was of all men the mod averfe from controverfy, the other mathema- ticians in Britain did not tamely fubmit to conclufions in direil oppofition to the fundamental doftrine of a philofopher of vvhofe talents the nation was juiUy proud. The confequence was, that the French government fent two difierent fets of meafurers,theonetomeafure a degree at the equator, the other at the polar circle ; and the couiparifon of the whole determined the figure to be an oblate fpheroid, contrary to Cafiini's determination. After a long and laborious life, James Caffini died in April 1756, in confequence of a fall, and was fuc- ceeded in the Academy and Obfervatory by the fubjeft of the following article. He publifhed, A Treatife on the Magnitude and Figure of the Earth ; as alfo, The Elements or Theory of the Planets, with Tables ; be- fide an infinite number of papers in the Memoirs of the Academy, from the year 1699 to 1755. C,Ji5;A7fl'i'7'(6ury(Cefar Fran cois),acelebrated French aftronomer, direftor of the obfervatory', penfioner aftro- nomer, and member of moff of the learned focieties of Europe, was born at Paris June 17. 1714, being the fe- cond fon of James Cafiini, the fubjcft of the preceding memoir, whofe occupations and talents he inherited and fupported with great honour. He received his firft leffons in aftronomy and mathematics from MM. Maraldi and Camus ; a^d made fuch a rapid progrefs, that when he was not more than ten years of age he calculated the phafes of a total eclipfe of the fun. At the age of eighteen he accompanied his father in his two journeys imdertaken for drawing the perpendicular to the ob- fervatory meridian from Strafbourg to Breft. From that time a general chart of France was devifed.; for which purpoie it was neceffai")- to traverfe the countiy by feveral lines parallel and ptrpendicuhir to the meri- dian of Paris, and our author was charged with tlie con- dudl of this bufinefs ; in which he was fo fcrupulous as. to meafure again what had been meafured by his father. This great work was publifhed in 1740, with a chart fiiewing the new meridian of Paris, by two different fe- ries of triangles, paffing along the fea coalfs to Bayonne, traverfing the frontiers of Spain to the Mediterranean and Antibes, and thence along the eaftern limits of France to Dunkirk, with parallel and perpendicular lines defcribed at the diftance of 6000 toifes from one another, from fide to fide of the country. A tour which, in 1741, pur author made in Flanders, in the train of the king, gave rife, at his majefty's in- llance, to the chart of France ; relative to which Caf- fini publifhed different works, as well as a great number of the fheets of the chart itfelf. In 1761 he under- took an expedition into Germany, for the purpofe of continuing to Vienna the perpendicular of the Pa- CAT [ i8i 1 C A T I Caflini II Catalojrues ris meridian ; to unite the triangles of the chart of more perfciS: ; but nothing has there been faid of their CadloRutJ France with the points taken in Germany; to pre- origin, or of tlic iifes which might be made of the oldclt "^ Co'-ks.^ pare the means of extendiiig into that comitry the catalogues. —— y— < fame plan as in France ; and thus to cilabllfh fuc- According to tlie ProRlTor, George Wilier, whom (.efiivcly for all Europe a moll ufeful uniforir.ity. — fomc improperly call Viller, and otiit-rs Walter, a book- Our author was at Vienna the 6lh of June 1761, the feller at Augibnrg, wiio kept a very large ihop, and dav of the tranfit of the planet Venus over the fun, of frequented the Fiaiickfort fairs, firlt fell upon the plan wliicli he obfervcd as much as the llate of the weather of caufuig to be printed, before every fair, a catalogue would permit him to do, and publilhed the account of of all the new books, in which the iize and printers it in his P'oya^e at Alkniagne. names were marked. Le Mire, better known under Finally, M. Caffuii, always meditating the perfeftion the name of Miiaeus, fays that catalogues were lirft of his grand defign, proiited of thepeace of 1783 to pro- printed in the year 1 554; but Labbe (a), Reimann (b), pofe the joininu- of certain points taken upon the Eng- and Heumann (c), who took their information from Le lilh coall with thofe which iiad been determined on the Mire, make the year erroncouily to be 1564. Willer's coaft of France, and thus to conned the general chart catalogues were printed till the year 1592 by Nicol. of the latter with that of the Britidi iflcs, like as he Balffeus, printer at Franckfort. Other bookfcllers, had before united it with thofe of Flanders and Gerrna- however, muft have foon publilhed catalogues of the like iiv. The propofal was favourably received by the Eng- kind, though that of Wilier continued a long time to liih government, and prefently carried into eti'edt under be the principal. the direftion of the Royal Society, the execution being committed to the late General Roy. tiee the life ot that general in this SuppUmsiit. Between the years 1735 and 177c, M. Caffini pub- lidied, in the volumes of Mem.oirs of the Fiencii Aca- demy, a prodigious number of pieces, confiding chief- ly of aftronomical obiervations and queftions ; among In all thele catalogues, which are in quarto and not paged, the following order is obfcrved. The Latin books occupy the full place, beginning with the Pro- tettant theological works, perhaps becaufe Wilier was a Lutheran ; then come the Catholic ; and after thefe, books of jurifprudencc, medicine, philofophy, poetry, and mufic. The fecond place is afligned to German wiiich are obfervable, refearches concerning the parallax books, which are arranged in the fame manner of the fun, the moon, Mars, and Venus ; ou altronomi- The bookiellers of Leipilc foon perceived the advan- cal refraAions, and the effedf caufed in their quantity tage of catalogues, and began not only to reprint thofe and laws by the weather ; numerous obfervations on the of Franckfort, but alfo to enlarge them with many obliquity of the ecliptic, and on the law of its variations, books which had not been brought to the fairs in tliat In fhort, he cultivated aftronomy for fifty years, the city. Our author had for fome time in his cuilody, moft important for that fcience that ever elapfed for Calalo^us univerjalis pre inmdinh Fraiucfurtcnjihus ver- tlie magnitude and variety of oljefts, in which he com- nu/ilus, de anno l6co; or, A catalogue of all the books monly fuftained a principal ihare. on fale in Book-lliect, Franckfort, and alfo of the books M. Caflini was nf a very ftrong and vigorous confti- publifhed at Leipfic, which have not been brought to tution, which carried him through the many laborious Franckfort, with the perniiliion of his highncfs the clec- operations in geography and aftronomy which he con- tor of Saxony, to thole new works wlu'ch have appeared dufted. An habitual retention of urine, however, ren- at Leipfic. Fiinted at Leipfic by Abraham Lamberg, dered the lafl twelve years of his life very painful and and to be had at his fnop. On the September catalogue diftreffmg, till it was at length terminated by the fmall- of the fame year, it is faid that it is printed from the poK the 4th of September 1784, in the 71ft year of his Franckfort copy with additions. He found an imperial age. He was fucceeded in the academy, and as di- privilege for the firll lime on the Franckfort September reftor of the obfervatory, by his only fon John-Do- catalogue of 1616: Cum gratia et privilegio fpeciali f. minic Caflini, the fourth in order of direft defcent who caef. maj. Projiat c.pud y. Krugcrum jiugujlar.um. has filled that honourable ftation. Reimmann fays, that after Willer's death the cata- CASTRAMETATION, the art or aeT; of encamp- logue was publilhed by the Leipfic bookfeller Henning mg an army. CATACAUSTICS, or Catacaustic Curves, in the higher geometry, are the fpecies of cauftie curves formed by refleftion. CATACOUSTICS,orCATAPHONics,is the fcience Grofle, and by his fon and grandfon. The council of Franckfort caufed feveial regulations to be iffued re- fpccting catalogues ; an account of which may be feen in D. Ortli's Yreatife on ibc Imperial Fairs at Franck- fort, After the bufinels of bookfeliing was drawn from of reflefled founds ; or that part of acoullics which treats Franckfort to Leipfic, occaiioned principally by the re- of the properties of echoes. ^ ftrictions to which it was fubjeded at the former by CATALOGUES of Books, is a fubjeft of which the cenfors, no more catalogues were printed there; a very curious hidory has been given to the world by and the fhops in Book-ilreet were gradually converted Profeflbr Beckmann. In the Encyclopa;dia mention has into taverns (d). been made of fome of the moft valuable catalogues, their " In the 16th century there were few libraries ; and deftfts pointed out, and rules given for making them thefe, which did not contain many books, were in mo- naiteriesj. (a) Labbe, Bibliotheca Bibliothecarum. Lipfiae, 1682, izrao, p. (b) Einleitung in die Hijloriam Literariam, i. p. 203. (c) Confpeftus Reip. Litter, c. vi. § 2. p. 316. (d) Joh. Adolpfi. Stock, Frankfurter Chronik, p. 77. 112. CAT L CatjloB"" nafterics, and cotififted principally of theological, philo- "[^■"''' ^ ^ - fopliical, and liiftorical works, with a few, however, on '^ ' iurifpnidtiice and medicine ; while thole whiili treated of agriculture, manufafturcs, and trade, were thounht unworthy of the notice of the learned, or of being pre- ferved in large colleftions. The number of thefe works was, neverthelefs, far from being inconfidcrable ; and at any rate, many of them would have been of great ufe, as thev would have ferved to illuftrace the inftrudtive hillory of the arts. Catalogues which might have given occafion to inquiries alter books, thai may be Hill fome- vvhere preferved, have fuffered the fate of tomb-ftones, which, being wafted and crumbled to pieces by the de- ftroying hand of time, become no longer legible. A complete feries of tliem perhaps is nowhere to be found, at lead I do not remember (fays the Profeflbr) to have ever feen one in any libra'ry." This lofs, however, he thinks, might be in fome mea- fure fupplied by the catalogues of Clefs and Draudius ; ti'ho, by the defire of fome bookfellers, collefted toge- ther all the catalogues which had been publiihed at the dilTerent fairs in different years. The work of Clefs has the following title : Unhis fscuTi cjufque virorum littera- toriim monumentis tumjlorcntijjimi, turn fertUjfimi, ab an- no I ceo ad 1602 nundinarum aulumnallum inclufiTe, elen thus confummat'ijfimus— defumtus part'tm ex fingularum nun- din.irum cntalcgis, partim ex Hbl'tothecis. Audore Joanne Cleflio, Wineccenfi, Hannoio, philofopho ac medico. — By the editor's preface, it appears that the firft edition was publi(hed in 1592. The order is aimed the fame as that obferved by Wilier in his catalogues. The work of Draudius, which was printed in feveral quarto volumes for the firft time in 161 1, and after- wards in 1625, is far larger, more complete, and more nethcdical. Our author, however, confeffes, that he never faw a perfeft copy of either edition. This cata- Io:t:'.rt. The author has pointed out the inllanccs of the in- • fufficiency of this method, and of the uncertain conclu- fions that are deduced from it, in determining the com- parative brightnefs of ftars found not only in Mr Flam- ftced's catalogue, but alfo in the catalogues of other aftronomers. It is fufficiently apparent that the prefent method of exprefting the brightnefs of the ftars is very defeflive. Dr Herfchel therefore propofes a difterent mode, that is more precife and fatisfaflory. " I place each ftar (he fays), inftead of giving its magnitude, into a fhort feries, conftrudled upon the or- der of brightnefs of the neareft proper ftars. Fur in- ftance, to exprefs the luftre of D, I fay CDE. By thij fhort notation, inftead of referring the ftar D to an imaginary uncertain ftandard, I refer it to a precife and determined exifting one. C is a ftar that has a greater luftre than D, and E is another of lefs brightnefs than D. Both C and E are neighboui ing ftars, chofen in fuch a manner that I may fee them at the fame time with D, and therefore may be able to compare them properly. The luftre of C is in the fame manner afcer- taiiied by BCD ; that of B by ABC ; and alfo the brightnefs of E by DEF ; and that of F by EFG. " That this is the moft natural, as well as the mofl: effeftual way to exprefs the Iirightnefs of a ftar, and by that means to deteft any change that may happen in its luftre, will appear, when we confider what is requifite to afcertain fuch a change. V/e can certainly not wifh for a more decifive evidence, than to be allured, by ac- tual infpeftion, that a certain ftar is now no longer more or lefs bright than fuch other ftars to which it has been formerly compared ; provided we are at the fame time affured that thofe other ftars remain flill in their former unaltered luftre. But if the flar D will no longrc ftand in its former order CDE, it mufl have undergone a change ; and if that order is now to be exprefTed by CED, the ftar has loft fome part of its luftre ; if, on the contrary, it ought now to be denoted by DCE, its brightnefs muft have had fome addition. Then, if we fliould doubt the ftability of C and E, we have recourie to the ordeis BCD and DEF, which exprefs their luftre ; or even to ABC and EFG, which continue the feries both ways. Now having before us the feries BCDEF, or if neceffary even the more extended one ABCDEFG, it will be impoflible to miftake a change of brightnels in D, when every member of the feries is found in its proper order except D." In the author's jouraal or catalogue, in which the order of the lufbe of the ftars is fixed, each ftar bears its own proper name or number, e. g. " the brightnefs of the ftar S Leonis may be exprefTed by /5 J 1 Leonis, or better by 94 — 68 — 17 Leonis; thefe being the numbers which the three above ftars bear in the Britidi catalogue of fixed ftars." This method of arrangement occurred to Dr Her- fchel fo early as the year 1782; but he was diverted from the regular purfnit of it by a variety of other .if- tronomical engagements. After many trials, lie prj- pofeJ, in the iranfaftions of the Royal Society of London for 1796, the plan which appeared to him the moft eligible. It is as follows: -Inftead of denoting particular ftars by letters, he snakes ufe of numbers ; and' in his choice of the ftars which are to exprefs the luftre of CAT [ Cata'.Oi^ues of any particular one, lie diretls his firft view to perfeft ofthe Scarf. eqygiity When two ftars feem to be finillar both in ' ' brightncfs and inngnitude, he puts down their numbers together, feparated merely by a point, as 30.24 Leonis; but if two ftars, which at firft feemed alike in their liiftre, appeared on a longer infpedtion to be diff'erent, and the preference ftiould be always decidedly in tavour of the fame ftar, he feparates thefe ftars by a comma, thus, 41,9+ Leonis. This order muft not be varied ; nor can three fiich ftars, as 20, 40, 39, Librx, admit of a different arrangement. If the ftate of the henvens ftiould be fuch as to require a different order in thefe numbers, we may certainly infer that a change has ta- ken place in the lullre of one or more of them. When two ftars differ very little in brightnefs, but fo that the preference of the one to the other is indilputable, the numbers that exprefs them are feparated by a (liort line, as 17 — 70 Leonis, or 68 — 17 — 70 Leonis. When two ftars differ fo much in brightnefs, that one or two other ftars might be interpofed between them, and ftill leave fufficient room for diftinftion, they are diftlnguilh- ed by a line and comma, thus, — , or by two lines, as 32— — 41 Leonis. A greater difference than this is denoted by a broken line, thus 29 Bootis. On the whole, the author obfervcs, the marks and diftinc- tlons which he has adopted cannot poffibly be miftaken ; " a point denoting equality of luftre ; a comma indica- ting the leall perceptible difference ; a ftiort line to mark a decided but fmall fuperiority ; a line and com- ma, or double line, to exprefs a confiderable and ftriking cxcefs of brightnefs ; and a broken line to maik any other fuperiority which is to be looked upon as of no ufe in eftimations that are intended for the purpofe of direfting changes." The difficulties that attend this arrangement are not difguifed ; but the importance and utility of it more than compenfate for the labour which it muft neccffarily require. By a method of this kind, many diicoveries of changeable and periodical ftars might probably have been made, which have efcaped the moft diligent and accurate obfervers. We might then, as the author fug- gefts, be enabled to refolve a problem in which we are all immediately concerned. " Who, for inttance, would not wifti to know what degree of permanency we ought to atcribe to the luftre of our fun ? Not only the ftability of our climates, but the very exiftence of the whole animal and vegetable creation itfelf, is involved in the queftion. Where can we hope to receive information upon this fubjeft but from aftrononiical obfervations i If it be allowed to ad- mit the fimilarity of ftars with our fun as a point efta- blifhed, how neceff^rj- will it be to take notice of the fate of our neighbouring/u/w, in order to guefs at that of our own ? That7?ar, which among the multitude we have dignified by the name oi fun, to-morrow may (low- ly begin to undergo a gradual decay of brightnefs, like fi Leonis, a Ceti, " Draconis, J" Urfse niajoris, and many other diminiftiing ftars that will be mentioned in my ca- talogues. It may fuddenly increafe, like the wonderful ftar in the back of Caffiopea's chair, and the no lefs re- markable one in the foot of Serpentarius ; or gradually come on like f> Geminorum, S Ceti, K Sagittarii, and many other increafing ftars, for which I alio refer to my catalogues ; and, laftly, it may turn into a periodical one of 25 days duration, as Algol is one of three days, 84 ] CAT i Cephei of fivf, (5 Lyrae of fix, » Antinoi of feven Cafalt days, and as many others as are of various periods." ofthe ! Having thus explained the general principle on which '' this catalogue is formed, as we find it in the author's firft memoir on the fubjeft, we muft refer tlie leader to the Doftor's own account for its particular arrange- ment; obferving only that the catalogue fubjoined com- prehends nine conftellations, which are arranged in al- phabetical order, witli the comparative brightni-fs of the ftars accurately ftated. In a fubfequcnt paper, publidi. ed in the fame volume, he has completely verified the utility of his method by experience, and ftiewn that there is no permanent change of luftre in the ftars. In the notes to his firft catalogue he mentioned a Herculis as a periodical ftar. By a feries of obfervations on this ftar, compared with ». OphiuchI, which was moft con- venicntly fituated for his purpofe, he has been able not only to confirm this opinion, but to afcertain its period. His obfervations are arranged in a table, by means of Avhich he determines that this ftar had gone through four fucceffive changes in an interval of 241 days ; and therefore the duration of its period muft be about fio days and a quarter. This faft concurs with other cir- cumftances in evincing the rotatory motion of the ftars on their axes. " Dark fpots, or large portions of the furface, lefs luminous than the reft, turned alternately in certain direttions, either towards or from us, will ac- count for all the phenomena of periodical changes in the luftre of the ftars, fo fatisfaftorily, that we certainly need not look out for any other caufe." If it be al- ledged that the periods in the change of luftre of fome ftars, fuch as Algol, ft Lyrte, i Cephei, and » Antinoi, are ftiort, being only 3, 5, 6, and 7 days refpeclively ; while thofe of Ceti, and of the changeable ftar in Hy- dra, and that in the neck of the Swan, are long, a- mounling to 331, 394. and 497 days; and that we cannot afcribe phenomena fo different in their duratioa to the fame caufe — it may be anfwercd to this objeftion, that the force of it is founded on our limited acquaint- ance with the ftate ofthe lieavens. To the 7 ftars, the periodical changes of which were before known, we may now add ^ Herculis, which performs a revolution of its changes in 60 days. " The ftep from the rotation of a Herculis to that of Ceti is far lefs confiderable than that from the period of Algol to the rotation of " Herculis ; and thus a link in the chain is now fupplied, which removes the objec- tion that arofe from the vacancy." The rotation of the fifth fatellite of Saturn is proved by the change ob- fervable in its light ; and " this variation of light, ow- ing to the alternate cxpofition of a more or lefs bright hemifphere of this periodical fatellite, plainly indicates that the fimilar phenomenon of a changeable ftar arifes from the various luftre of the different parts of its lur- face, fuocefiively turned to us by its rotatory motion." Befides, we perceive a greater fimilarity between the fun and the ftars, by means of the fpots that muft be admitted to exift on their furfaces, as well as on that of the fun. Dr Herfchel farther obferves, that the ftars, befides a rotatory motion on their axes, may have other move- ments ; " fuch as nutations or changes in the inchna- tion of their axes ; which, added to bodies much flat- tened by quick rotatory motions, or furrounded by rings like Saturn, will eafJy account for many new phenome- CAT [ »85 3 C A T CnKinaria, na tliat may tlien offer ttiemfelvcs to our extended views." C;\th3nnt. 'p,, djij p;,pe,- jj likewife fnbjoined a catalo^rue of nine ' conftdlatioiis ; an.' the author promifei to e;ivc' the whole of them in fuccefllve (hort catalogues on the fame phn. CATENARIA, or C.^ten.^ry Curve. See En- cycl. and Arch in this Sufyplemenl. CATH \RI-^4E II Eniprefs of all the Riiflias, aft- ed fo confpicuous a part on the theatre of the world ; pofTcfled fuch uncommon povrers of mind, highly culti- vated by fcience and literature ; and was fuch a patron- efs of fcience and literature in others —that it cannot be deemed foreign from a work of this nature to give fome account of the principal events of her more pri- vate life. Sophia Augusta Frederica, who, upon her mar- riage to the grandfon of Peter the great, affumed the name Cath.'vrcna Alexievna, was born at Stettin on the 2d of May 1729. Her father was Chriftian .A.u- guftus, prince of Anhalt Zerbft Dornburg, at that time major general in the Pruffian fervice, commander in chief of the regiments of infantry, and governor of the town and fortref? of Stettin. Her mother, who was born princefs of Holftein Eutin, was a woman of great parts and beauty, of nearly the fame age with the prince-royal of Pruflja, afterwards Frederic the Great, with whom file kept up a regular correfpondence, and who after- wards contributed to the aggrandifement of her daugh- ter. This accomplllhed princefs took upon herfeli the care of educating the young Sophia, whom fhe brought up in the fimpkft maimer, and would not fuffer to ex- hibit the Icaft fymptoms of that pride to wliich fhe had fome proDenllty from her earlielt childhood. The confequence of this falutary reftraint was, that good hu- mour, intelligence, and fpirit, were even then the ftri- klng features of her youthful charafter. Being natu- rally addifted to reading, to reflcftlon, to learning, and to employment, (he was taught tlie French and other fafhionable languages ; and was inftrufted to read fuch books chiefly as might make her acquainted with hifto- ry and with the principles of fcience ; whilft the doArines of the Lutheran religion were carefully explained to her by a divine, who little thought how foon his illullrious pupil would embrace another faith. The Emprefs Elizabeth, who then fwayed the fcep- tre of Rullia, had in early life been promifed in marriage to the young prince of Holftein Eutin, brother to the princefs of Anhalt Zerbft ; but at the indant when the marriage was about to be celebrated, the prince fell fick and died. Elizabeth, who loved him to excefs, became inconfolabk, and in the bitternefs of her grief made a •vow of celibacy. This vow, though fenfual, and even Saicivlous, flie kept fcf far as never publicly to acknow- ledge any man as a hufband ; and upon her afcending the throne of her ancertors, (he called her nephew the Buke of Holftein Gottorp to her couit, where he was lolemnly proclaimed, when fourteen years ot age. Grand Duke, with the title of Imperial HIghnefs, and decla- red fncceflor to the Emprefs Elizabeth. 1 o fecure the fucceflion in the family of Peter the Great, the Emprefs was very defirous to have her nephew married ; and the princefs of Anhalt Zerbft, not ignorant of the tender remembrance which fhe ftill prefer ved for her brother, conceived the idea of placing, by means of it, her daugh- ter on the throne of Ruflia. She communicated her SuppL. Vol. I. Part I. plan to the king of PralTia, who not only applauded it, Ci'hnri • but lent her his affiftance to cany it into execution. """ Full of ambitious hopes, therefore, the princefs re- paired with her daughter to St Peteilburg, where (he was received with frienrifhip by F.li/.abetli, and where the young Sophl-i foon made a. conliderable imprefTion on the mind of the Grand Duke. As Peter was well made, of a good figure, and, though uneducated, not deftitute of natural talents, the attachment became reci- procal ; and the princefs of Zerbft, throwing hcrlelf at the feet of the empref?, affured her, that the two lovers were attached to each other by a paflion uuconqner.ible ; and, calling to her mind the lote which (he had herfelf borne to the prince of Holflein, conjured her to pro- mote the happinefs of that prince's niece. The ftrata- gem fucceeded. The choice of Elizabeth was next day announced to the council and to the foreign minifters ; and preparations were made for celebrating the mar- riage with a magnificence worthy of tlie heir of the throne of the RulTias. In the mean time the Grand Duke was feized with the fmall-pox, from which, th>>' he recovered, it was with fuch a change of features, as rendered him, from being comely, almofl hideous, and converted the love of the young princefs of .'\nh:ilt, if indeed (he ever felt for him tiiat paffion, into horror and dilguft. She was not, however, of a dilpofition to let a disfigured countenance frighten her from a throne. She embraced the Greek religion, changed her name from Sophia Augufta Frederica to Catharina .\i.exi- EVNA, and with the entire approbation of Elizabelli was married to her iiepheu' the Grand Duke. For fome time this ill-matched pair lived together, though without love, yet on terms apparently decent ; but a mutual dlflike gradually took place between them, which the courtiers quickly difcovered, and were at pains to foment into hatred. Peter was now ugly, and his mind was uninformed. Catharine, if not a beauty, was at leaft a lovely woman, and highly accompli fhed. She could find no entertainment in his converfation, and he felt himfelf degraded by her fuperiority. A faction was formed at court, headed by the great chancellor BeftuchefF, to exclude the Grand Duke from the throne, and to place Catharine at the head of affairs ; and to accomplifh this end, every art was employed to till the feeble mind of the emprefs with jealoulies of her nephew, and with a contempt of his clnraAer. He was repre- fented at one time as extremely ambitious, and capable of the moft daring enterprifes, to get immediate poftef- (ion of the throne ; and at another, as a wretch given up to drunkennefs and to every unprincely vice. The confequence of the firft of tlufe accufations was, that he was kept at a diftance from his aunt, and a ftranger to public afjairs ; and being wholly unemploy- ed, that time which his education had not fitted him to fill up with reading, refledlion, and rational converfa- tion, hung fo heavy on his mind, that it was no diffi- cult matter f'.r thofe diflipated young men, who were placed about him for that very purpofe, to initiate him in the habits of drunkennefs, and the otdei mean prac- tices to which it was pretended he had long been de- voted. In fuch a fcliool, it wai. no wonder that he be- came a proficient in grovelling difTipatlon ; or that, be- ing unpolifhed, and even of rude manners, he chofe for his companions fome of the ioweft of the people. Catharine, in the mean time, ianguifhed for that hap- A a pincis CAT [18 CatTiarine. plnefa which (he could not find in the foclcty of her * * hufband. She was fond of pleafure ; but It was that comparatively refined pleafure whicli (he had enjoyed at the court of Berlin. She loved balls, mufic, and ele- gant converfation, and could take no (hare in the drunk- en revels of Peter. Among the young men with whom lie was furrounded, his chamberlain Soltikoff was parti- cularly remarked for the elegance of his tafte and the graces of his perfon ; and though yet fcarcely more than a boy ill years, he was faid to have obtained the favours of feveral ladies of the court. Succtls had made him conlident and ambitious ; and his ambition prompted him to afuire at making a conqueft even of the Grand Duchefs. By ftudying her tafte, and contriving to amufe her, he was at lall fuccefsful ; and obtained from her Imperial Higbnefs every favour which he could wifh : but he enjoyed not his fortune with moderation, and his enemies contrived to get him placed in an ho- nourable oiTice at a-dlftance from the court. He wss commiflioned to repair to Stockholm, with the title of Envoy Extrsordinary, to notify to the king of Sweden the birth of Paul Petrovitch, of whom the Grand Duch- * 0(51. 1, efs had juft been delivered *. The prefuinptuous Solti- '754- koif, proud of the employment, fet off with halle to Sweden, and left it with equal fpeed. But fcarcely had he quitted Stockholm, on the wings of love and ambi- tion, when he was (lopped on the road by a courier, who put into his hands an order for him to go imme- diately to Hamburg, and there to refide in the quality of minifter plenipotentiary from the court of Ruflia. Catharine for fome time preferved her attachment to the exiled chamberlain ; but all at once the prefence of a ftranger, whom fortune had brought to the court of Ruflia, made her forget the lover whom (he no longer faw. This perfon was Staniflaus Poniatowlliy, the late king of Poland, who (irft m:ide his appearance at St Pe- teriburg in the train of the Britiih ambaflador, and very quickly gained the affeftions of the Grand Duchefs. In carrying on this intrigue, the lovers were not fo cau- tious as to deceive the eyes of the envious courtiers, who reported to the emprefs not only all that they faw, but whatever they fufpefted. Elizabeth was incenfed, and commanded Ponlatowfliy to quit without delay the domi- nions of RufTia. The accomplifhed Pole obeyed ; but foon returned clothed with a charafter which made him in fome degree indeoendent of the emprefs. The Count de Bruhl, then prime minifter to the king of Poland, faw of what importance it was to his mafter to have a povrerful inteieft at the couit of Riif- fia. He was likewife no ftranger to the p^fiion which the Grand Duchefs entertained for Poniatow(l.omen; invited foreigners of all nations, pofTtlTed of any merit, to fettle in different parts of lier vaft territories; increa- fed the naval force of the empire ; and gave fuch en- couragement to the cultivation of every elegant and ufe- ful art, that in the (hort fpace of a year and a half from her acceffion to the throne, the national improvement of Ruffia was vifible. In the good fortune and glory of Catharine, no one rejoiced more fincercly than Count Poniatowfty. He approached towards the confines of Ruffia, and wrote to her in the tendereft Ryle of congratulation, requeft- ing riermifTion to pay his refpetls to her in the capital of htren.pire It is not improbable that he flattered himfelf with the hopes that fhe would give him her hand in marriage, and thus raife him to the throne of the Tzarsi ; but fhe hadpromifed to the Emprcfs Eli- zabeth, that (he would never again lee the count ; and to ih-t promife fhe at prefent adhered. She wrote to him, however, in the moll affeftionate terms ; and tho' fhe ga<^ him no encouragement to repair to St Pttevl- burgh, fhe affured him that flie had other profpefts in view for his aggrandi'tment. and that he might depend upon her perpetual fiicr.dfhip : and (he foon appc.red to be as good as her word. On the death of Auguftus III. (he raifed her foimtr favourite to the throne of Poland, in oppofition to the wilhes of the courts of Vienna and Verfaillts, as well as of a great majority of the Polidi nobles. Slie defeated the intrigues of the two foreign courts by more flcilfuUy cor.duifttd intrigues of her own ; and by pourirg her armies into tlie re- public, (he fo completely overawed the nuncios, that Poniatowficy was chofen by the unanimous fulFrages of the diet which met for the ekftion of a fovereign ; and, on the 7th of September 1764, was proclaimed Kmg of Poland and Grand Duke of Lithuania, by the name of Stanidaus Augulfus. Whilft file was thus difpofing of foreign kingdoms, fhe was kept under perpetual dread of being tumbled from the throne of her own vaft empire, f ler want of title to that throne was now feen by all ranks of her fubjefts : the good qualities of Peter the third were remembered, and his failings and faults forgotten. His fate was univerfally lamented ; and, except the confpi- rators, who may be faid to have embrued their hands in his blood, there was hardly a Ruffian who did not regret that the fovcreignty had palfed from the ancient family of the Tzars to a foreigner, allied only by mar- riage to the blood royal. Even the confpirators them- felves had loft much of their regard for Catharine. The princefs of Dafhkoff was a fecond time banifhed to Mofcow ; and, to magnify her own importance, fhe fpoke freely of the means by which the emprefs, whom ■ fhe accufed of ingratitude, had been raifed to the throne. The inhabitants of Mofcow, who never favoured the ufurpation, were thus made ripe for a revolt. At St Peterfburgh, Count Panin felt himfelf uneafy under the predominant influence of the favourite, and tried in vain to divert Catharine's aflfeftions to a new objeft. She received a few fecrct vifits from a handfome young man, and then appointed him to a luciatfve and honourable employment in fome diftant province of the empire; r 190 1 CAT when Orloff recovered his former afcendency, which Cathiulnsi through his own carelefTnefs lie had nearly loft. In v~-^ this Hate of the public mind, confpiracies were very frequent ; and as the general objeft of them was to place on the throne Prince Ivan, who v/as again lan- gui(hing in the dungeon from which Peter had taken him, the emprefs had given to his guard an order, fign. ed by her own hand, to put that unfortunate prince to death, (hould any attempt be made to liberate him from his prifon. An attempt was made by a very inferior officer, as fome have fuppofed, by thevinftructions of Catharine, and her bloody order was inftantly obeyed. The aflaffins were rewarded, and promoted in the ar- my; but the officer who attempted to refcue the prince was condemned to death, and fuft'ered unexperledly the fentencc of the law. The brothers and iilters of Ivan, who had been kept in a prifon difterent from his, were fent to Denmark ; and, to provide them with nccef- fanes fuitable to their rank, tlie emprefs nisde them a prefent of 2co,ooo rubles, and paid annually, to the maintenance of their dignity, a penCon of thirty thou- fand. The throne of Catharine was now firmly eftablilhed, by the death or renunciation of every perfmi who was defcended of the imperial family ; and (he had leifure to turn her thoughts to the aggrandifement of the em- pire. It was foon feen that this was the objetl which fhe had in view when (lie raifed Count Poniatowfky to the throne of Poland, and that (lie was not adtuated on that occafion by any remains of her former attachment. We have elfewhere (hewn (fee Poland, Encycl. n" 98 — 115) under what pretences (he invaded the kingdom of him who had formerly been one of her moft favour- ed lovers, and by what means (he annexed great part of it to the territories of Ruffia. But it is not through her wars that in this article we mean to trace her cha- ra6ter : It is not as a fovereign and heioine that her life is entitled to a place in a general repolitory of aits, fciences, and mifcellaneous literature, but as a patronefa of art and of fcience, and as the legiflalrix of a valt em- pire, who employed all her talents and all her power for the civilization of a great part of the human race. Under the article Russia (Encyc/.), we have men- tioned the famous coife of laivs for a great empin; and the propofed convention 0/ deputies from all the claffes, which Catharine and the Princefs Da(hkofF fo artfully employed as means to bring about the revolution which feated the former on the throne. The Hates adually met in the ancient capital of the em;'lre, and the fove- rei^n's inftruftions for framing: a new code of laws was read amidll reiterated burits of applaule. All prefent extolled the lagacity, the wifdom, the humanity of the emprefs ; but fear and flattery had a greater (hare ia thefe exclamations than any jull knowledge of the lub- jeft. The deputies of the Samoides alone had the courage to fpcak freely. One of them ftood up, and, in the name of himfelf and his brethren, faid, " We are a fimple and honeft people. We quietly, tend our rein- deer. We are in no want of a new code ; but make laws for the Ruffians, our neighbours, that may put a ftop to their depredations." The following fittings did not pafs fo quietly. A debate about the liberation of the boors was carried on with fuch warmth, that fa- tal confequences were to be apprehended ; and the de- puties were difmilTed to their refpe£tive provinces irt the CAT [ I9T ] CAT the minner which we have elfc^where related. Previ- ' oils, }iowever, to the dilTolution of this afTembly, the members weie required to fi^nah'ze the meeting by fome confpicuous aft of o-ratitiule ; and, by a sre'ieial acclamation, the titles of Great, Wise. Prudfnt, and Mother of the Country, were decreed to the emprefs. With affiimed modefby fhe accepted only of the laft, "as the moft benign and glorious recompence for her labours and folicltudes in behalf of a people whom {he loved." For that people Hie did indeed labour, and labour moil ufe'iilly. She introduced into the adminiftration of juftice the f^reitell reformation of which the halfci- v'lized Itate of Ruffia would perhaps admit. She fpa- red neither trouble nor expence to diffufe over the em- pire the light of fcience, and the benefits of ufefiil and elegant arts ; and (he protefted, as far as (he could, the poor from the opprelTIons of the rich. About the middle of 1767, (lie conceived the idea offending feve- ral learned men to travel through the interior of her vaft dominions, to determine the geographical pofition of the principal places, to mark their temperature, and to examine into the nature of their foil, thelr_ vegetable and mineral produftions, and the manners of the peo- ple by whom they were inhabited. To this employ- ment fhe appointed Pallas, Gmelin, Euler, and many others of the higheft eminence in the republic of letters ; from whofe journals of thefe interefting travels large additions have been made to the general ftock of ufe- ful knowledge. This furvey of the empire, and the maps made from it, had Catharine done nothing elfe, would alone have been fufficient to render her name im- mortal. Well convinced inkier own mind, that it is not fo much by the pov^er of arms, as by precedence in fcience, that nations obtain a conlpicuous place in the annals of the world, with a laudable zeal (he en- couraged artiils and fcholars of all denominations. She granted new privileges to the two academies of fciences and the arts ; encouraged fuch of the youth as had be- haved well in thefe national inftitutes, to travel for far- ther improvement over Europe, by beflowing upon them, for three years, large penfions to defray their expence ; and, to remove as mr.eh as poflilile the Ruffian pre- judice againft all kinds of learning, (lie granted patents of nobility to thofe who, during their education, had con- dufted themi'elves with propriety, and become profi- cients in any branch of ufeful or elegant knowledge. Still farther to encourage the fiine arts in her domi- nions, (he affigned an annual fum of 5000 rubles for the tranflatioti of foreign literary works into the Ruffian language. In the year 1768, the fmall-pox raged at St Peterf- burgh, and proved fatal to vail numbers of all ranks and of every age. The emprefs was defirous to intro- duce the praftice of inociilation among her fubjefts ; and refolved to fet the example by having herfelf and her fon inoculated. With this view, (he applied for a phylician from England : and Dr Thomas Dimfdale of Hertford being recommended to her, he repaired with his fon to the capital of Ruffia, where he inoculated firll the emprefs, then the grand duke, and afterwards many of the nobility. The experiment proving fuc- cefsful, he was created a baron of the empire, appoint- ed aftual counfellor of ftate, and phyfician to her impe- rial majefty, with a penfion of L. 300 fterling a-year, to be paid him in England, belides L. i o,ooo which he im- Catharuie. mediately received. So popular was the emprefs at ■— v~~^ this period, that, by a decree of the fenate, the anni- verfary of her recovery from the fimll pox was enjoin- ed to be celebrated as a religious fellival ; and it has ever fi.ice been obfcrved as fuch. She was now eigaged in war with the Turks, of which a fufficient account for a work of this nature has been given under the title Turkky (Encycl); but there was one tranfaftion of her and her friends, of which no mention was made in that article, thougli it is of importance to him who would form a jull eltimate of her perfonal charafter. We have noticed the fenfuality of the emprefs Eliza- beth. She bore three children to the grand veneur Alexey Gregorievifch Razumofffliy, to whom, indeed, fne is faid to have been clandellinely married. Of thefe children the youngefl was a gitl, brought up under the name of Princefs Tarrakanoff. Pi ince Radzivil, who has been mentioned in the article Poland ( Eiicycl.Jy irritated at Catharine's cruelties to his countrymen, conceived the project of placing the young princefs on the throne of her ancellors ; and, having gained over the perfons to whom her education was intnilled, he carried her off to Rome as a place of fafely. Catha- rine, in return, feized his large eftates ; and he and the princefs were reduced to extreme poverty. Radzivil repaired to Poland in order to learn what could be done to forward his great enterprife ; and fcarcely had he ar- rived there when an offer was made to rcllore to him his pofferGons, upon condition of his carrying his ward to St Peter(burgh. This he refufed : but hid the bafe- nefs to promife, that he would give himfcLf no farther concern about the daughter of Elizabeth ; and he was put in poffeffion of all his ellates. By the inftruftions of the emprefs, Alexius Ovloff, who nominally commanded the Ruffian fleet at the Dar- danelles, repaired to Rome, got accefs to young Tar- rakanolf, and found means to perfuade her that all Ruf- fia was ready to revolt from Catharine, and place her on the throne of her mother. To convince her of his fincerity, he orctended to feel for her the tendered and moft refpeftful paffion ; and the unfufpicious lady was induced to accept of him as a hufband. The ruffian who had affaffinated the grandfon of Peter the Great, did not hefitate to feduce and betray his grand daughter. Under pretence of having the marriage ceremony per- formed according to the rites of the Greek church, he uiborned fome fubaltern villains to perfouate priells and lawyers ; thus combining profanation with impofture againft the unprotefted and too confident Tarrakanoff. Having been treated for fome days, both at Rome and at Leghorn, with all the refpedl due to a fovereign, the unfufpefling princefs exprelTed a wi(h to go on board a Ruffian (hip of war. This was juft what Or- loff wanted. Attended by a numerous and obfequious train, (he was rowed from the fhore in a boat with mag- nificent enfigns, hoifted upon the deck of the (hip in a fplendid chair, and immediately handcuffed. In vain did (lie throw herfelf at the feet of her pretended huf- band, and conjure him by every thing tender which had paffed between them. She was carried down into the hold ; the next day the veffel failed for St Peterf- burgh ; where, upon her arrival, the princefs was (hut up in the fortrefs ; and what became of her fince was never CAT [ 192 1 CAT CiUharinf. never known. Sucli were the mens which Catharine '"""''"""' fcruplcd not to employ in oider to gtt rid of all pre- tenders to her throne. Soon after this fervice rendered to her by Alexius Orloff, (he difinifed hi:i brother Gregory from her fa- vour, and ronnefled herfelf with Viffiltohikoff, a fub- lientenant of the guards. The foimor favourite li^d indeed become infolent, and, as Catharine th JUffht, ungrateful. He afpircd to nothing lefs than the throne. Ffom love to hlmfelf, and to a fon which (he had born to him, (he offtred to enter into a fecret marriage ; but with this propofal the proud prince (a) was nat fatis- ficd, and hoped that his refufal would impel her to re- ceive him publicly as her hufband and partner in power. He was miftaken. She diveftcd him of alt his employ- ments ; but gave him a penfion of t one or the other to preponilerate — (hew how admirably fhe was qualified to guide the helm of a greit empiic ill all its traulatlions with foreign (l-ites. We fpeak not o^'the fjuitv of her proceeding.;; for it mull be confclTed, that equitv formed no barrier agiiuH hei am- bition ; and that (he never failed to fubjugate thofc w'lom (lie pictended to take under her proteftion. Her ruling paffion was to enlarge her own territories, al- ready fj very extenfive ; and, for the attainment of that oUjcil, (be contrived the mod judicious plan', which (he executed with vigour. In this pirt of her conduft, hi>w'vdr, fhe has been equalled by other monarchs ; but in the 7.'*al and the wiliom with which flie endeavoured to introJuce among her hali-favage fubjeifts the blef- fings of knowledge and indudry, (he ftands unrivalled, except, perhaps, by her predecefl'or Peter the Great. Of this we need bring no other proof, in addition to what has beea already dated, than that (he founded in St Peterfburgh alone thirty-one ieminaries, where 6800 children of both fexes were educated at the annual ex- pence to the government of 7 51,3 ^ J rubles. She fu- perintended herfclf the education of her grandchildren, and wrote for them books of inftruAion. If it be true, that " every man acquainted with the common principles of human aftion, will look with veneration on the wri- ter who is at one time combating Locke, and at another making a catechifm for children in their fourth year ;" with what veneration (hould we look upon the emprefs of Ruffia, could we forget the means by which (he ob- tained that elevation from which Hie frequently defcend- ed for a fimilar employment : This (he did, not for her own delcendants alone, but alfo for the children of others ; of whom (he had always a great number in her apartments, who fhared in the inftruiSion given to her grandchildren, and wliofe caitfles (he returned with ex- treme complaifance. Her greated weaknefs was furely that grofs paffion which her panegyrids have dignified with the name of love ; but to fuch an appellation it had no claim, if love be any thing more than a fexual appetite. Befides Gregory Orloff, (he had not fewer than ten favourites atter the death of her hufband ; and of thefe (he feems to have felt a refined affection for none but Lanfltoi, a young Pole of a very ancient family, and of elegant manners, and the famous Potemkin, to whom (he is faid fecretly to have given her hand, and who prcfer- ved her friendfhip, if not her affeftion, to the end of his life. To Lanfkoi, whofe education had been much neglefled fhe condefcended to become precepttix ; and, as he made great piogrefs in the acquifition of ufeful knowledge, (he admired in him her own creation Po- temkin, though not amiable, deferved her favour for the fidelity and abilities with which he ferved her, both in the council and in the field ; and in him, when (lie .. had ceafed to look on him with the eyes of love, (he refpefted the intriguing politician and intrepid com- mander, who had formed plans tor driving the Turka out of Europe, and fetting her on the throne of By- zantium. Her other favouritea had nothing to recom- mend (a) She had fome time before obtained for him a patent, creating liim a prince of the Roman empire. CAT [ "'"e mend them but mafculine beauty and corporeal ftrength. ~~ One of them, however, thought it nectflary to have a library in ihe grand hoiife, of which the cnnprefs, upon receiving him into favour, had made him a prefent ; and dcfired thr principal bookfcller to fill his {helves. The man allied him what books he would pleafe to have. " You under ftand that better than I (replied the fa- vourite) ; that is your bufinefs. You know the pro- per aflbrtments ; I have dellined a large room to receive them. Let there be large books at the bottom, and fmaller and fmaller up to the top ; that is the way they Hand in the emprefs's library!" In the converlation of fuch men the cultivated mind of Catharine could en- joy no interchange of fentiments. We know not whether that more than Afiatic mag- nificence, which (he difplayed on every public occafion, {hould be confidered as an inftance of weaknefs or of wifdom. If fhe delighted in balls, and malquerades, and fumptuous entertainments, and drefs loaded with jewels, and every kind of fplendid ornament, for their own fakes, Ihe betrayed a weaknefs unworthy of that fovereign who held in her hand the balance of Europe, and at whofe nod the greateft powers of Afia trembled : but if (he introduced fuch fplendorinto her court mere- ly to divert the attention of the Ruffians from the means by which Ihe got pofleffion of the throne, and to ween them from their own favage and flovenly manners ; even this may perhaps be conlidtred as one of her moft maf- terly ftrokes in politics. Her ambition was boundlefs ; but, if fuch a phrafe may be allowed, it was not always true ambition. When the French republic had eftabliihed itfelf on the ruins of monarchy, and was propagating new theories of govern- ment through all Europe, true ambition would furely have led the autocratrix of the north to unite her forces with thofe of the coalefced powers, in order to crufh the horrid hydra, before its anarchical principles could be introduced among her own barbarous fubjei^s. .Such would certainly have been the advice of her favourite Potcmkin, who longed to lead a Ruffian army into France, even before the murder of the unfortunate Lewis. That general, however, had died in OAober 1791 ; and when Britain, Auftria, and Pruffia, were leagued againft the new republic, Catharine looked coolly on, in hopes, it is probable, of availing herfelf of their weaknefs, when exhaufted by a long and bloody war. She gave refuge, indeed, in her dominions to many emigrants from France, and fent a fqir.idron of fhips to co-operate with the navy of England : but in this laft ineafure fhe regarded merely her own immediate inte- reft ; for her crazy fhips were repaired by Britifh car- penters at the expence of the Britifh government, and her officers had an opportunity of learning the evolu- tions of the Britifh navy. She had likewife other prof- pefts in view when (he lent to the allies this flender aid. She meditated a new war with Turkey ; and, depend- ing upon meeting with no oppoStion, if fhe fhould not receive affiftance from England and Auftria, (he Hattcr- «d herfelf with accomplifliing her dailing projeft of driving the Ottomans out ot Europe, and of reigning in Conftantinople. But fhe was difappointed. On the morning of the 9th of November 1796, fhe was feized with what her principal phyfician judged a fit of apo- plexy ; and, at 10 o'clock in the evening of the follow- ing day, expired, in the 68th year of her age, leaving Suppi. Vol. I. Part I, 93 ] C A U behind her the charafter of one of the gre«teft I'ove- reign» that ever fwayed a fceptre. After this long detail of the incidents of her life, it ie necdlefs to inform the reader that Catharine II. had no religion, and, of courfc, no principles of morality, which could induce her in every inftance to do to others as (he would have them do to her. She was a prufeded difciple of the brench philofophers ; by fome of whom flic was ridiculed, and by others cheated. The iacenfe which (he paid to the genius of Voltaire did not hinder him trom frequently breaking his jefts upon the auto- cratrix of RufTia and her fuccelTive favourites ; and Di- derot, whom fhe careffed, fold to her an immcufe li- brary, when he pofTeffed hardly a book, and was obli- ged to ranfack Germany and France for volumes to enable him to fulfil his bargain. Such is the friendfhip, and fuch the gratitude, which fubfilU among the ami- able pupils of nature, and the philanthropic advocates for the rights of man. CAUDA Capricorni, a fixed ftarof the fourth mag. nitude, in the tail of Capricorn ; called alfo, by the Arabs, Dineb Algedi i and y by Bayer. Cauda Cett, a fixed (lar of the third magnitude ; called alfo, by the Arabs, Dined Kaetos ; marked fi by Bayer. Cauda Cygni, a fixed (lar of the fecond magnitude, in the Swan's tail ; called by the Arabs Dineb .iJigege', or ElJegiagich ; and marked a by Bayer. Cauda Delphini, a fixed liar of the third magnitude, in the tail of the Dolphin. ; marked ; by Bayer. Cauda Draconis, or Dragon's tail, the moon's fouth- ern or defcending node. Cauda Leonis, a fixed ftar of the firft magnitude, in the Lion's tail ; called aifo, by the Arabs, Dine'> E!e- ced ; and marked ^ by Bayer. It is called alfo Lucida Cauda. Cauda Urfie Majoris, a fixed ftar of the third mag. nitude, in the tip of the Great Bear's tail ; called alfo, by the Arabs, Alalioth, and Bensnath ; and marked „ by Bayer. Cauda Urfe Minoris, a fixed ftar of the third maq//im — and [SuppL) Action and Astronomy. CENTER, or Centre, a word borrowed from the French name ceitUre or cintre, given to the frame of tim- ber, by which the brick or ftone of arched vaulting is fuppotted during its ereftion, and from which it re- ceives its form and curvati:re. It is not our intention to defcribe the variety of con- ftruftions which may be adopted in eafy fituations, where the a:ches are of fmall extent, and where fuffi- cient foundation can be had in every part of it for fuu- pnrting the frame. In fuch cafes, the frequency of the props wliich we can fet up difpenfes with much care ; and a frame of very (light timbers, connefted together in an ordinary way, will fuKce for carrying the weight, and for keeping it in exaft fliape. But when the arches liave a wide fpan, and confequently a very great weight, and when we cannot fet up intermediate pillars, either for want of a foundation in the foft bottom of a river, or becaufe the arch is turned between two lofty piers, as in the dome of a (lately cathedral — we are then obli- o-ed to reft every thing on the piers themfelves ; and the framing which is to fupport our arch before the key- ftone is fet, muft itfelf be an arch, depending on the mutual abutment of its beams. One fhould think that this view of the conftruftion of a centre would offer it- felf at the firft, naturally derived from the ereftion it was to affift : but it has not been fo. When intermedi- Cc&Ditioc. 2 Purpofe of this aitide ate pillarj were not employed, it was ufual to frame the Centtr. mould for the arch with little attention to any thing but •' "' its fliape, and then to crofs it and recrofs it in all direc- tions with other pieces of timber, till it was thought fo bound together that it could be lifted in any pof:tion, and, when loaded with any weight, could not change its .fliape. The frame was then raifed in a lump, like any lolld body of the fame fliape, and let in its place. This is the way ftill pradliftd by many country artills, who, having no clear principles to guide them, do not flop till they have made a load of timber almoft equal to the weight which it is to carry. But this artlefs method, betides leading the employer into great expence, is frequently fatal to the undeitake"-, frpm the unflcilfulnefs of the conflruftion. The beams which conneft its extremities are made alfo to fuppott the middle by means of polls which reft on them. They are therefore expoled to a tranfverfe or crofs (Irain, which they are not able to bear. Their number muft. therefore be incieafed, and this increafes the load. Some of thele crofo ftrains are derived from beams which are prefl'ed vety obliquely, and therefore exert a prodigious thruft on their fuppoits. The beams are alio greatly ■ weakened by the niortifes whidi are cut in them to re- ceive the tenons of the croffing beams : and thus the whole is exceedingly weak, in proportion to what the fame quantity of timber may be made by a proper dif- pofitlon.of its parts. The principles from which we are to derive this dif- General polition are the general mechanical principles of carpen- 1 rincijlts try, of which we have given fome account in that ar-"'*^™'"''^ tide. Thefe furnilh one general rule : When we would ' ' give the utmoft ftrength poffible to a frame of carpen- try, every piece (hould be fo difpofcd that it is fubjedt to no ftrain but what cither puflies or draws it in the direfiion of its length : and, if we would be indebted to timber alone for the force or ftrength of the centre, we muft reft all on the lirft of thefe ftrains ; for when the draining force tends to draw a beam out of ita place, it mull be held there by a mortife and tenon, which pofleiTcs but a very trifling force, or by iron ftraps and bolts. Cafes occur where it may be very difBcult to make every ftrain a thruft, and the beft art- ifts admit of ties ; and indeed where we can admit a tie-beam connefting the two feet of our frame, we need feek no better fecurity. But this may fometimes be very inconvenient. When it is the arch of a bridge that we are to fupp(r.t, fuch a tie-beam would totally ftop the paffage of fmall craft up and down the river. It would often be in the water, and thus expofed to the moft fatal accidents by frefhes, &c. Interrupted ties, therefore, muft be employed, whofe joint or meetings muft be fupported by fomething analogous to the king- pofts of roofs. When this is judicioufly done, the fe- curity is abundantly good. But great judgment io ne- ceffary, and a very fcrupulous attention to the difpofi- tion of the pieces. It is by no means an eafy matter to difcern whether a beam, which makes a part of our centre, is in a ftate of comprefiion or in a ftate of ex- tenlion. In fome works of the moft eminent carpen- ters even of this day, we lee pieces confidered as ftruts (and contiderablc dependence had on them in this ca- pacity), while they are certainly performing the office of tie-beams, and fhoidd be fecured acceordingly. This was the cafe in the boldeft centre (we think) that has beea iiefs and iireugtli. C E N [19 Center been executed in Europe, that of tlie bridge of Oileans, ^""—t by Mr Hupeau. Yet it is evidently of great confe- qucnce not to be miftaken in this point ; for when we are miftaken, and the piece is ftretched which we ima- gine to be compretTed, we not only are deprived ot fome fupport that wc expcfted, but the cxpefted fuppott Tias become an additional load. * ,., To afcertain this point, we may fiippofe the piers tincuiih a '° yield a little to the prelTure of the aichftoncj on the ftrijt from 3 centre frames. The feet, therefore, fly outwards, and tie. the (hape is altered by the finking of the crown. We mult draw our frame anew for this new ilate of things, and n'.uft notice what pieces mud be made longer than before. All fuch pieces have been afting the part of tie-beams. But a centre has ftill another office to fuftain ; it muft keep the arch in its form ; that is, while the load on the centre is continually increaling, as the n.alons lay on more courfes of arch (tones, the fiame mud not yield and go out of Ihape, finking under the weight on the haunches, and rifing in the crown, which is not yet carrying any load. The frame muft not be fuDple ; and mud derive its ftiffnefs, not from the clofenefs and ftrength of its joints, which are quite infignificant when * fet is competition with fuch immenfe ftrains, but from {Iruts or ties, properly diipofed, which hinder any of the angles from changing its amplitude. It is obvious, from all that has been faid, that the How to fc- ftrength and ftiffnefs of the whole muft be found in the cureftifF- triangles into whicli this frame of carpentry may be re- folved. We have feen that the ftrains which one piece produces on two others, with which it meets in one ^ point, depends on the angles of their interleftion ; and that it is greater as an obtfJe angle h mote obtufe, or an acute angle more acute. And this fiiggefts to us the general maxim, " to avoid as much as pofiible all very obtufe angles.'' Acute angles, which are not ne- ceftarily accompanied by obtufe ones, are not fo liurtful; becaufe the drain here can never exceed the ftraiuing force ; whereas, in the cafe of an oblufe angle, it may fuipafs it in any degree. Such are the general rules on this fubjeft. Although fomething of the mutual abutment of timbers, and the fupport derived from it, has been long perceived, and employed by the carpenters in roofing, and alfo (doubt- lefs) in the forming of centres, yet it is a matter of hi- ftorical faft, that no general and diftinft views had been taken of it till about the beginning of this century, or a little earlier. Fontana has preferved the figure of the frames on which the arches of St Peter's at Rome were., turned. The one employed for the dome is conftruft- ed with viry little fitill ; and thofe for the arches of the nave "Slid tranfepts, though incomparably fuperior, and of confiderable fimplicity and drcngth, are yet far infe- rior to others which have been employed in later times. It is much to be regretted that no trace remains of the forms employed by the great architeft and confummate mechanician Sir Chridopher Wren. ,We Ihould doubt- lefshave feen in them every thing that fcience and great fagacity could fugged. We are told, indeed, that his centering for the dome of St Paul's was a wonder of its kind ; begun in the air at the height of 160 feet from • the ground, and without making ufe of even a projeft- ing coiniche whereon 10 reft it. The earlicft theory of the kind that we have met ] C E N with, that is propofed on fcicntific principles, and with Cci-.tjr. the exprcfe purpufe of ferving as a Icflbn, are two cen- ~~~^~~~' tres by Mr I'itot of the Academy of Sciences, about the The eai lied beginning of this century. As they have confidcrable tl cory, on merit (greatly refcmbling thofe employed by Michael f'''-'''''^' Angelo in the nave of St Peter's), and aft'ord fome good l"'""^'l''"' maxims, we diall give a (hort account of them. We crave the excufe of the attifts if we fhould employ their terms of art fomewhat aukwardly, not being very fami- harly acquainted with them. Indeed, we oblerve very great differences, and even ambiguity, in the terms em- ployed. What we fliall defcribe under the name of a cen/re Is (properly fpeaking) only one frame, trufs, or rib, of a centre. They are fet up in vertical planes, parallel to each other, at the didance of ;, 6, 7, or 8 feet, like the truflfes or main couples of a roof. Biidging joifts are laid acrofs them. — In fmaller works thefe are laid fparingly, but of confidcrable fcantling, and are board- ed over ; but for great arches, a bridging joift ia laid for every courfe of archltones, with blockings between to keep them at their proper diilances. The dones are not laid immediately on thefe joifts, but beams of foft wood are laid along each joift, on which the done is laid. Thefe beams are afterwards cut out with the chiffel, in order to fepatate the centre from the ring of Hones, which muft now fupport each other by their mu- tual abutment. 7 The centre is diftinguiftiable into two parts, ALLB lUudrated. (fig. I.) ar.d LDL, which are pretty independent ofphteXIV. each other, or at lead a6t feparately. The horizontal Stretcher LL cuts the femicircle ADI3 halt way be- tween the fpring and the crown of the arch ; the arches AL, LD, being 45" each. This fttetcher is divided in the fame proportion in the points G and H ; that is, GH is one half of LL, and LG, HL are each one- fourth of LL nearly. Each end Is fupported by twvo Struts EI, GI, which red below on a Sole or Bed properly fupported. The interval between the heads of the ftruts GI, HK is filled up by the Straining Beam GH, abutting in a proper manner on the ftruts (fee Carpentry, Supplement), The extremities L, L, are united in like manner by butting joints, with the heads of the outer ftruts. The Arch Moulds AP, BP, are connected wldi the ftruts by crofs pieces PQ. which we (hall call Bridles, which come inwards on each fide of the druts (being double), and are bolted to them. This may be called the lower part of the frame. The upper part confids of the king poft DR, fupported on each fide by the two ftruts or braces ML, ON, ir.ortifed into the poft, and alfo mortifed into the ftretcher, at the points L, N, where it is fupported by the (truts below. The arches LD, LD are conneded with the druts by the bridles PQ, in the fame manner as below. g There is a great propriety in many parts of this ar- Proi riety rangement. The lower parts or haunches of the arch "^ ''''» '•"• prefs very lightly on the centres. Each archdone is ly. r^ngstu'it- ing on an inclined plane, and tends to Aide down only with its relative weight ; that is, its weight is to its tendency to Aide down the joint as radius to the fine of elevation of the joint. Now it is only by this tendency to Aide down the joint that they prefs on the centering, which in every part of the arch is perpendicular to the joint : But the preCTure on the joint, arifing from this caufe, 13 much lefs than this, by reafon of the friftion of B b 2 the C E N [ 196 ] C E N Centir. the joints. A block of dry fict-ilone will not Aide down ' ' » at all ; and therefore will not prels on t!ie centering, if the joint be not elevated ;?5 degrees at leaft. But the aiclilfones are not laid in this manner, by Aiding them down along the joint, but are laid on the centres, and Aide down their flope, till they touch the blocks on which they are to reft ; fo that, in laying the arch- ftones, we are by no means allowed to make the great deduction fiom their weight juft now mentioned, and which Mr Couplet prefcribcs (Mem. Acad. Sciences, 1729). But there is another caufe which diminiflies the preffure on the centres ; each block Aides down the ■ planks on which it is laid, and prcfies on the block be- low it, in the direftion of the tangt-nt to the arch. This prefTure is tranfmi'.ted throui^h this block, in the fame diredlion, to the next, and through it to the third, &c. In thij manner it is plain that, as the arch advances, there is a tangential preffure on the lower archflones, which diminilTies their prefTure on the frame, and, if fufficiently great, might even pufh them away from it. Mr Couplet has given an analyfis of this preffure, and (hews, that in a fcmicircular arch of uniform thickntfs none of the arch flones below 30° prefs on the frames. But he (without faying fo) calculates on the fuppofi- tion that the blocks defcend along the circumference of this frame in the fame manner as if it were perfeftly fmooth. As this is far from being the cafe, and as the obftruftions are to the laft degree various and irregular, it is quite ufelefs to inftitute any calculation on the fub- jeft. A little refleftion will convince the reader, that in this cafe the obftruftion arifing from friftion mufl be taken into account, and that it mujl not be taken into account in cftimating the prefTure of each fucceflive courfe of ftones as they arc laid. It is enough that we fee that the prefTure of the lower courfes of archftones on the frame is diminiflied. Mr Couplet fays, that the whole prefTure of.a femicircular arch is but ^ths of its weight ; but it is much greater, for the reafon jufl now By a centre given. We have tried, with a well made wooden mo- ot M. Pi- del (of which the circumference was rubbed with black lead to render it more flippery), whether onj' part of the wooden blocks reprefenting the archftones were detach- ed from the frame by the tangential prelTure of the fu- perior blocks ; but we could not fay confidently that any were fo detached. We perceived that all kept hold of a thin flip of Chinefe paper (alfo rubbed with black lead) between them and the frame, fo that a fenfible force was required to pull it out. From a combination of circumi\anres, which would be tedious to relate, we believe that the centres carry more than two- thirds of the weight of the arch before the keyftone is fet. In elliptical and lower pitched circular arches, the propor- tion is (till greater. It feems reafonable eoough, therefore, to difpofe the framing in the manner propofed by Pitot, directing the main fupport to the upper mafs of the arch, which prefTes mofl on the frame. We fhall derive another ad- ■vantage from this conitruftion, which has not occurred to Mr Pitot. There is an evident propriety in the manner in which he has diflributed the fupports of the upper part. The flruts which carry the king poll fpring from thofe points of the flretcher where it refls on the flruts below : thus the flretcher, on which all depends, bears no tranfverfe drains. It is ilretched by the &rut above it, and.it ig tot's. comprcfTtd in a fmall degree betvi'een the ftriits below Cfnttr. it, at leaf! by the outer ones. Mr Pitot propofes the """v— ~ (training beam GH as a lateral fupport to the flretcher, which may therefore be of two pieces : but although it (lots augmmt its ftrenglh, it does not feem necefl'arj' for it. The flretcher is abiuidanlly carried by the ftrap, which may and fhould fiifpend it from the king poll. The great ufe of the flraining piece is to give a firm abut- ment to the inner llruts, without allowing any lateral flrain on the flretcher. N. B. Great care muft be ta- ken to make the hold fufficiently firm and extenfive be- tween the flretcher and the upper flruts, fo that its co- hetion to relift the thrulls from thcfc flruts may be much employed. The only imperfefiion that we find in this frame is the lateral flrains which are brought upon the upper ftruts by the bridles, which certainly tranfmit to them part of the weight of the archftones on the curves. The fpace between the curves and ML fhould alfo have been trufTed. Mr Pitot's form is, however, extremely ftifT ; and the caufing the middle bridle to reach down to the ftretcher, feems to fecure the upper ftiuts from all rifle of bending. This centre gives a very diftinft view of the ofSces of all the parts, and makes therefore a proper introduc- tion to the general fubjeiSl. It is the fimplell that can be in its principle, becaufe all the elTential parts are fub- jefted to one kind of (train. The flretcher LL is the only exception, and its extenfion is rather a collateral circumftance than a ftep in the general fupport. 10 The examination of the ftrength of the frame is ex-T"he tremely eafy. Mr Pitot gives it for an arch of 60 feet ^^^"g''' ^^ fpan, and fuppofes the archftones 7 feet long, which is a monftrous thicknefs for fo fmall an arch ; 4 feet is an abundant allowance, but we (hall abide by his conftruc- tion. He gives the following fcantlings of the parts : The ring or circumference conCfts of pieces of oak 12 inches broad and 6 thick. The ftretcher LL is 12 inches fquare. The ftraining piece GH is alfo 12 by 12. The lower ftruts 10 by 8. . The king poft 12 by 12. The .upper ftruts 10 by 6. The bridles 20 by 8. Thefe dimenfions are French, which is about ~i\t\t larger than ours, and the fuperficial dimenfions (by which the fedlion and the abfolute ftrength is meafured) is almoft 4^th larger than ours. The cubic foot, by which the ftones are meafured, exceeds ours nearly j-th. The pound is deficient about rVth. But Cnce very nice calculation is neither eafy nor necefTary on this fub- jedl, it is needlefs to depart from the French meafures, which would occafion many fraftional parts and a trour blefome reduflion. The arch is fuppofed to be built of flone which, weighed 160 pounds per foot. Mr Pitot, by a compu* tation (In vhich he has committed a miftake), fays, that only T^ths of this weight is carried by the frame. We believe, however, that this is nearer the truth than Mr Couplet's afTumption of ^^ths already mentioned. Mr Pitot farther alTumes, that a fquare inch of found oak will carry 8640 pounds. By his language we (hould imagine that it will not carry much more ; but this is very far below the ftrength of any Britifh oak that we have tried ; fo far, indeed, that we rather ima- gine C E N [ Computed. Cf r.ter. gine that he means that this load may be laid on it with ■"'>"■"' ptrfeA fecurity for any time. B'.it to compenfate for krota and other accidental imperfcftlons, he atTumcfi 7200 as tlie meafure of its abfohite force. He computes the load on eacti frame to be 707520 pounds, which he reduces to -J-jths, or 55590S pounds. The abfolute force of each of the lower ftruts is 576000 (at 7200 per inch), and that of the curves 5 1 8400. Mr Pitot, confiderinjr that the curves are kept from bending outwards by the arch-ftones which prefs on them, thinks that they may be conlidered as aSing precifely as the outer ftruts EI. We have no objettion to this fuppofition. With thefe data we may compute the load which the lower trufs can fafely bear by the rule delivered in the article Carpentry. We therefore proceed as fol- lows : Meafure off by a fcale of equal parts a s, at, each 576000, and add /-u 518400. Complete the paralle- logram avKs, and draw the vertical xc, meeting the horizontal line aC in f. Make cb equal to en. Join xb, and complete the parallelogram ax by. It is evi- dent that tlie diagonal xy will reprefent the load which thefe pieces can carry ; for the line a-u 1% the united force of the curve AP and the ftrut IE, and as Is the flrer.gth of IG. Thefe two are equivalent to a x. It h is, in like manner, equivalent to the fupport on the other fide, and xy is the load which will jull balance the two fupports a x and b x. When xy is meafured on the fajne fcale, it will be found = 28 50000 pounds. This is more than five times the load which aAually lies on the frame. It is therefore vaftly ftronger than is necelTary. Half of each of the. linear dimenfions would have been quite fuf- ficient, and the ftruts needed only to be 5 inches by 4. Even this would have carried twice the weight, and would have borne the load really laid on it with perfeA fefety. We proceed to meafure the ftrength of the upper part. The force of each ftrut is 432000, and that of the curve is 518400; therefore, having drawn M.v pa- rallel to the ftrut ON, make Mw =r 432000, and Ms = 432C00 -1- 518400. Complete the parallelogram hii rv. Draw the horizontal line r i, cutting the ver- tical MC in i, and make iy =: Mi. It is plain, from what was done for the lower part, that Mji will mea- fure the load which can be carried by the upper part. This will be found = 1160000. This is alfo greatly fuperior to the load ; but not in fo great a proportion as the other part. The chief part of the load lies on the upper part ; but the chief reafon of the diflerence is the greater obliquity of the upper ftruts. This fhort- ens the diagonal My of the parallelogram offerees. Mr Pitot (hould have adverted to this ; and inftead of ma. king the upper ftruts more flender than the lower, he fliould have made them ftouter. The ftrain on the ftretcher LL is not calculated, It IS meafured by r' i', when My is the load actually ly- ing on the upper part. Lefs than the fixth part of the cohcfion of the ftretcher is more than fuflkient for the 97 ] C E N horizontal thruft ; and there is no difficulty of making Center. the foot joints of the ftruts abundantly ftrong for the ' \r— ' purpofe. The reader will perceive that the computation juft now given does not ftate the proportions of the ftrains aaiuilly exerted on the dlff'erent pieces, but the load on the whole, on the fuppofition that each piece is lubjeft- cd to a ftrain proportioned to its ftrength. The other calculation is much more complicated, but is not necef- fary here. This centre has a very palpable defeiS. If the piers fliould yield to the load, and the feet of the centre fly out, the lower part will exert a very confiderable ftrain on the ftretcher, tending to break it acrofs between N and L, and on the other fide. HKFof the lower part is firmly bound together, and cannot change its ftiape,. and will therefore zSl like a lever, turning round the point F. It will draw the ftrut HK away from its a- butment with GH, and the ftretcher will be ftrained acrofs at the place between H and F, where it is bolt- ed with the bridle. This may be refifted in fome de- gree by an iron ftrap uniting ON and HK ; but there will ftill be a want of proportional ftrength. Indeed, in an arch of fuch height (a femicircle), there is but little rifk of this yielding of the piers ; but it is an im- perfeftion. ^ The centre (fig. 2.) is conftrufted on the fame prin-A centre- clple precifely for an elliptical arch (a). The calcula-"" the fame- tion of its ftrength is nearly the fame alfo; only the '"^''"^'P''^? two upper ftruts of a fide being parallel, the parallelo- [?,'!ji ^j j,'''' gram Msrv (of fig. 1.) is not needed, and in its ftead w^ meafure off on ON a line to reprefent twice its ftrength. This comes in place of Mr' of fig. i. — N. B. The calculation proceeds on the fuppofition that the fiiort ftraining piece MM makes but one firm body with the kingpoft. Mr Pilot employed this piece (we pre- fume) to feparate the heads of the ftruts, that their ob- liquity might be leffened thereby : and this is a good thought ; for v/hen the angle formed by the ftruts on each fide is very open, th-e ftrain on them becomes very great. The ftretcher of this frame is fcarfed in the middle. Suppofe this joint to yield a little, there is a danger * of the lower Itrut ON lofing its hold, and ceafing to join in the fupport : for when the crown finks by the- lengthening of the ftretcher, the triangle ORN of tig. 2. will be more diftorted than the fpace above it, and ON will be loofened. But this will not be the cafe when ■ the finking of the crown arifes from the mete com. prefQon of the ftruts. Nor will it happen at all in the centre, fig, i. On the contrary, the ftrut ON will abutt more firmly by the yielding of the foot of MI.,. The figure of this arch of Mr Pilot's confifts of three arches of circles, each of 60 degrees. As it is elegant,, it will not be unacceptable to the artift to have a con- ftruftion for this purpofe. Make BY = CD, and CZ = -l CY. Defcribe the.Howw femicircle ZjEY, and make ZS = "LM. S is the centre conftrua of the fide arches, each of 60 degrees. Tlie centre T of '>"^'' ^n the.*''*'- (a) It is the middle arch of the bridge at Lille Adam, of which Mr Pitot had the direftion. It is of 80 feet fpan, and rifes 31 feet. C E N r 19S ] C E N Center, tlie arcli, vhlch unites thefe two, is at the angle of an ^-"■y^—^ equilateral triangle STS. This conftruiSion of Mr Pitot's makes a liandfome oval, and very near an ellipfis. but lies a little without it. We fhall add another of our own, which coincides with the ellipfe in eight points, and furrifhes the artift, by the way, a rule for drawing an infinite variety of ovals. Let AB, DE (fig. 2. N" 2.) be the axes of an el- lipfe, C the centre, and F, /"the two foci. Make C^ = CD, and dtfcribe a circle ABie paffing through the three given points A, D, and i. It may be de- monftrated, that if from any ptiint P of the arch AD be drawn a chord PD, and if a line PR r be drawn, making the angle DPR = PDC, and meeting the two axes in the points R and r, then R and r will be the centres of circles, which will form a quarter APD of an oval, which has A3 and DE for its two axes. We want an oval which fhall coincide as much as poflible with an elliplis ? The moft likely method for this is to find the very point P where the ellipfis cuts the circle ADl>e. The eafieft way for the artift is to dtfcribe an arch of a circle a m, having AB for its ra- dius, and the remote focus/for its centre. Then fet one foot of the compaffes on any point P, and try whe- t'.ier the diftance PF from the nearcll focus F is exaol- ly equal to its diftaixe P m from that circle. .Shifting the foot of the conipafTc i from one point of the arch to another, will foon difcover the point. This being found, draw PD, make. the angle DP r — PD r, and R and r are the centres wanted. Then make C s z^ CR, and we get the centres for the other fide. The geometer will not relifh this mechanical conftrnc- tion. He may therefore proceed as follows : DrawDrf parallel to AB,"cutting the circle in d. Draw e 1^^ cut- ting AC in N. Draw CG parallel to Ae, and make the angle CG i = AD e. Bifedl CN in O, and join O ('. Make OM, OM' = O i, and draw MP, MT perpen- dicular to AJi. Thefe ordinates will cut the circle ADie in the points P and P', where it is cut by the ellipfe. We leave the demonftration as a geometrical t . « €xercife for the dilettante. Centre for We faid, that this centering of Mr Pitot's refembled the nave >jf In principle the one employed by Michael Angelo for St Peter's, ^^^g ^^^^ ^^jj tranfepts of St Peter's church at Rome. Fontana, who has preferved thi», afcribes the contlruc- tion of it to one of the name of San Gallo. A ilcetch of it is given in fig. 3. It is, however, fo much fupe- rior, and fo different in principle, from that employed for the cupola, that we cannot think it the invention of the fame perfon. It is, like Pitot's, not only divifible, but really divided into two parts, of which the upper carries by much the greateft part of the load. The pieces are judicioufly dilpofed, and every important beam is amply fecured againll all tranfverfe Itrains. Its only fault is a great profuGon of ilrenglh. Ihe innermoft polygon aghb is qviite fuperfluo-js, becaufe no ftrain can force in the ftruts which reft on the angles. Should the piers yield outwards, this polygon will be loofe, and can do no fervice. Nor is the triangle gih oi any ufe, if the king-poft above it be ftrapped to the tie-beam and ftraining fill. Perhaps the inventor confidered the king- poft as a pillar, and wifhed to fecure the tie beam againft its crofs ftrain. This centering, however, muft be al- lowed to be very well compofed ; and we expecl that the well-informed reader will join us in preferring It to Ccnrrp. Mr Pitot's, both for fimplicicy oi principle, for fcienti- ^""^ "^ fie propriety, and for ftrength. Thereis one confiderable advantage which may be de- rived from the aClual div'non of the tnifs into two parts. If the tie-beam LL, inftead of refting on the ftretcher EF, had rcfted on a row of chocks formed like double wedges, placed above each other, head to point, the up- per part of the centering might be ftruck iniiependent of the lower, and this might be done gradually, begin- ning at the outer ends of the ftretcher. By this proce- dure, the joints of the arch-ftones will clofe on the haunches, and will almnft relieve the lower centering, fo that all can be pulled out together. Thus may the arch fettle and conlolidate in perfect laftty, without any chance of breaking the bond of the mortar in any part ; an accident which frequently happens in great arches. This procedure is peculiarly advKable for low pitched or elliptical arches. But this will be more clearly fcen af- tenvaids, when we treat of the iiitcrnal movements of an arch of mafonrj'. This may fuffice for an account of the more fimple conftrui5tion of trufted centres ; and we proceed to fuch as have a much greater complication of principle. We (hall take for examples fome conftrufted by Mr Perro- net, a very celebrated French architeft. j. Mr Perronet's general maxim of conftruftion is to Perrrjnet's make the trufs confift of feveral courfes of feparate truf- "'^■'"'" "f fes, independent (as he thinks) of each other, and thus^."" ^"'^" to employ the joint fupport of them all. In this con- ftruftion it is not intended to make ufe of one trufs, or part of one trufs, to fupport another, as in the former iet, and as is praAifed in the roofs of St Paul's church, Covent Garden, and in Drury Lane theatre. Each trufs fpans over the whole diftance of the piers, and would iband alone (having, however, a tottering equili- brium). It confifts of a number of ftruts, fet end to end, and forming a polygon. Thefe truffes are fo ar- ranged, that the angles ot one are in the middle of the fides of the next, as when a polygon is infcnbed in a circle, and another (of the fame number of fides) is cir- cumfcribed by lines which touch the circle m the angles of the infcribed polygon. By this conftruftion the angles of the alternate trufTcs lie in lines pointing to- wards the centre of the curve. King-pofts are there- fore placed in this direftion between the adjoining beams of the truffes. Thefe king-pofts confill of two beams, one on each fide of the trufs, and embrace the trufs- beams between them, meeting in the mid:!le of their thicknefs. The abutting beams are mortlfed, half into ^ each half of t^.e poft. i he other beam, which makes the bafe of the triangle, paffes through the poft, and a ftrong.bolt is driven through the joint, and fecu.ed by a key or a nut. In this manner is the whole united ; and it is expefted, that when the load is laid on the up- permoft truls, it will all butt together, forcing down the king poft<:, and therefore preffmg them on the beams of all the inferior truffes, caufing them alfo to abutt on each other, and thus bear a ftiare of the load. Mr Pcrronet does not affume the invention to himfelf ; but fays that it was invented and praftifed by Mr Manfard de Sa- gonne at the great bridge of Moulins. It is much more ancient, and is the work of the celebrated phyfician and architeft Ferrault ; as may be feen in the coUeftion of machines and inventions of that gentleman publifhed af- ter C E N [ 1 ter his death, and alfo in tht greit tolkftion of inven- tions approved of by the Academy of Sciences. It i» this which we propofe to examine. Fig 4. reprefents tlie centering employed for the bridge of Ciavant. The arches are eUlptlcal, of 60 feet fpan and 20 feet rife. The archftoncs are four feet thick, and weigh 176 pounds per foot. The tiuis- beam the unreduced load on each frame was very nearly 23 c tons. The fcantling of the ftruts was 1 5 by 1 2 inches. The principle is the fame as that of the former. Phe chief diffeience is, that in this centre the outer trufs- bcaiB of the lower row is not coupled with the middle row.y Center. ti' Max. ence. Neiiilly, C E N [2 row, but kept nearly parallel to tlie rvutor the flatnefs at the crown ; for about 26 feet on each fide of the middle it was intended to be a portion of a circle of 150 feet radius. An arch (femicircular) of ^00 feet fpan might therefore be eafily conftruAed, and would be much ftronger than this, becaufe its horizontal thruft at the crown would be vallly greater, and would keep it more firmly united. The bolts of this centre are differently placed from thofe of the former ; and the change is judicious. Mr Perronet had doubtlcfs found by this time, that the ftiffnefs of his framing depended on the tranfverfe ftrength of the beams ; and therefore he was careful not to weak- en them by the bolts. But notwithftanding all his care, the framing funk upwards of 1 3 inches before the key- ftones were laid ; and during the progrefs of the work, the crown rofe and funk, by various fteps, as the loading 00 ] C E N was extended along it. When 20 courfes were laid on Ccter. each fide, and about 16 tons laid on the crown of each *—- v— ■ frame, it funk about an inch. When 46 coiirfcs were laid, and the crown loaded with 50 tons, it funk about halt an inch more. It conlirued finking as the work advanced ; and when the key Hone was fct it had funk i^i inches. But this finking was not general ; on the contrary, the frame had rifen greatly at the very haunch- es, fo as to open the upper pait of the joints, many of which gaped an inch ; and this opening of the joints gradually extended from the haunches towards the crov.'ii, in the neighbourhood of which they opened on the under fide. i'his evidently arofe from a want of ftiffnefs in the frame. But thefe joints clofed again when the centres were ftruck, as will be mentioned af- terwatds. *- We have taken particular notice of the movements and twilling of this centre, becaufe we think that they indicate a deficiency, not only of ftiffnefs, but of abut- ment among the trufs beams. The whole has been too flexible, becaufe the angles are too obtufe : This arifes fiom their multiplicity. When the intercepted arches have fo little curvature, the power of the load to prefs it inward Increafes very fait. When the in. tercepted arch is reduced to one half, this power is more than doubled ; and it is alfo doubled when the radius of curvature is doubled. The king polls (hould have been farther apart near the crown, fo that the quantity of arch between them (hould compenfate for its diminilhed curvature. The power of withftanding any given inequality of load would therefore have been greater, had the centre confifted of fewer pieces, and their angles of m:eting been proportionally more acute. The greattft improve- ment would have been, to place the fool of the lower tier of trufs-beams on the very foot of the pier, and to have alfo feparated it at the head from the reft with a longer king-poft, and thus to have made the diftances of the beams on the king-pofts increafe gradually from the crown to the fpring. This would have made all the angles of abutment more acute, and would have pro- duced a greater prelTure on all the lower tiers when the frame fagged. Fig. 7. reprefents the centering of the bridge of Or-Q , ^° leans. The arch has 100 feet fpan, and rifes 30, and the arch-ftones are 6 feet long. It is the conftruAion of Mr Hupeau, the firft architeA of the bridge. It is the boldell work of the kind that we have leen, and is conftrufted on clear principles. The main abutments are few in number. Becaufe the beams of the outer polygon are long, they are very well fupported by ftraming beams in the middle ; and the ftruts or braces which fupport and butt on them, are made to reft on points carried entirely by ties. The inventor, however, feems to have thought that the angles of the inner po- lygon were fupported by mutual compreflion, as in the outer polygon. But it is plain that the whole inner polygon may be formed of iron rods. Not but that both polygons may be in a ftate of compreflion (this i» very poffible) ; but the fnialleft fagging of the frame will change the proportions of the preffures at the an- gles of the two polygons. The preffures on the exte- rior angles will incrcale, and thofe on the lower or iu- terior angles will diminilh moft rapidly ; fo that the a- butraents in the lower polygon will be next to no- thing. Center. Inflrufllvi; Mftory of this centre C E N [ 20! ] C E N thin^. Such points could bear very little prcfTiire from the whole load (fny hy doubling its beams), and we Center, the braces which fupport the middle of the long bear- may then make the lo'vcr polygon of (lender dimen- v~~~- ings of the upper beams, and their prtflures mull be fions, provided we fecure the joint.'; on the k.ing-p(jfts borne chiefly by the joints fiipported by the king-pofts. by iron ftraps which embrace a confiderable portion of The king-pofts would then be in a ftate of extenfion. the tie on each fide of thf joint. 2, It is difficult, however, to decide what is the precife We are far from thinking that thefe centres are of .-ill th'fe ftate of the preffure at thefe interior angles. the befl kind that could be employed in their fituation •,«'"|=, The hiftory of the ereftion of this bridge will throw mucli light on this point, and is very inftruftive. Mr Hupeau died before any of the arches were carried far- ther than a very few of the firft courfes. Mr Perronet fucceeded to the charge, and finifhed the bridge. As the work advanced, the crown of the frame rofe very itiuch. It was loaded ; and it funk as remarkably. This (hewed that the lower polygon was giving very little aid. Mr Perronet then thought the frame too weak, and inferted the long beam DE, making the diagonal of the quadrangle, and very nearly in the di- but thcv are excellent in their kind : and a careful^/ >rt'J ill ftudy of them will teach the artift much of his profef- fion. When we have a clear conception of the (late of ftrain in which the parts of a frame really are, we know what (hould be done in order to draw all the ad- vantage polTible from our materials. We have faid in another place, thnt where we can give our joints fufii- cient connexion (as by flraps and bolts, or by cheeks or fifhes), it is better to ufc ties than ftruts, becaulc ties never bend. We do not approve of Mr Perronet's praftice of gi cheir kiiiJ. reiStion of the lower beam a h, but falling rather below ving his trulTes fuch narrow feet. By bringing the foot this line. He now found the frame abundantly llrong. It is evident that the trufs is now changed exceedingly, and confills of only the two long fides, and the (hort ftraining beam lying horizontally between their heads. The whole centering confifts now of one great trufs aY^el, and its long fides aY^, eb, are truffed up at B artdy. Had this fimple idea been made the principle of the conllruftion, it would have been excellent. The angle a DE might have been about 176*^, and the po- lygon D c A ^ employed only for giving a flight fup- port to this great angle, fo as not to allow it to exceed of the lower polygon farther down, we greatly diminirti all the drains, and throw more load on the lower poly- gon : and we do not fee any of Mr Perronet's centres where this might not have been done. He feems to af- fedl a great fpan, to (hew the wonders of his art ; but our objedl is to teach how to make the bell centre of a given quantity of materials ; and how to make the moll perfett centre, when we are not limited in this refpecl, nor in the extent of our fixed points. H We (hall conclude this feries of examples with one '^f'^-ll<;^i=e where no fuch affeftation takes place. This is the cen- "' '"^^ '^f'" 180". But Mr Perronet found, that the joint c, at the tering of the bridge at Blackfriars, London. The fpaa'/j f,,"''""''' foot of the poll E c, was about to draw loofe, and he of the arch is 100 feet, and its height from the fpring Blackfriars was obliged to bolt long pieces of timber on each fide is about 4^. The drawing fig. 8. is fufliciently minutel'fiJge- of the joint, embracing both beams. Thefe were evi- to convey a diftinft notion of the whole conilrudlion. dently afting the fame part as iron ftraps would have We need not he very particular in our obfervations, af- done ; a complete proof that, whatever may have been ter what has been faid on the general principles of con- the original prefFures, there was no abutment now at ftruftion. The leading maxim, in the prefent example, the point c, and that the beams that met there were feems to be, that every part of the arch fiall be fupported not in a ftate of compreflion, but were on the ftretch. by a fimple trufs of two legs refl'm^, one on each pier. H, H, &c. are called apron piecfs, to ftrengtheii the exterior joints and to make the ring as ftiff in itfelf as poffible. From th« ends of this apron-piece proceed the two legs of each trufs. Thefe legs are 12 inches fquare : They are not of an entire piece, but of feveral, meeting in firm abutment. Some of their meetings are Mr Perronet fays that he put thefe cheeks to the joints tofliffen them. But this was not their office ; becaufe the adjoining beams were not ftruts, but ties, as we have now proved. We may therefore conclude, that the outer polygon, with the alTiftance of the pieces a b, DE, were carrying the whole load. We do not know the diftance between fecured by the double king-pofts, which grafp them the frames ; but fuppofing them fevcn feet apart, and firmly between them, and are held together by bolts, the arch 6 feet thick, and weighing 170 pounds per foot, At other interfeftions, the beams appear halved into we learn the load. The beams were 16 inches fquare. each other; a pradlice which cannot but weaken them If we now calculate what they would bear at the fame much, and would endanger their breaking by crofs very moderate rate allowed to the other centres, we find drains, if it were poflible for the frame to change its that the beams AB and ab are not loaded to one-fixth fhape. But the great breadth of this frame is an ef- of their ftrength. _ feftual flop to any fuch change. The faft was, that We have given this centre as a fine example of what no ftnkinn or twijUng whatsiier was oLferved during the carpentry is able to perform, and becaufe, by its fim- progrefs of the mafon work. Three points in a ftiaight plicity, it is a fort of text on which the intelligent ar- line were marked on purpufe for this obfervaiion, and tift may make many comments. We may fee plainly were obferved every day. The arch was more than lix that, if the lower polygon had been formed of iron rods, feet thick; and yet the finking of tlie crown, before firmly bolted into the feet of the king-pofts, it would fetting the k~y-ftones, did i),jt amount to one inch, have maintained its fhape completely. The fervice done The centre employs about one-third more timber by the beam DE was not fo much an increafe of abut- than Perronet's great centre in proportion to the fpan ment as a difcharge of the weight and of the pull at the of the arch ; but the circumference incrcafes in :i joint c. Therefore, in cafes where the feet of the trufs greater proportion than this, becaufe it is more f leva- are necejarily confined to a very narrow fpace, we (hould ted. In every way of making a comparifon of the di- be careful to make the upper polygon fuificicnt to carry meufions, Mr Mylne's arch employs more timber ; bat SuppL. Vol. I. Part T ' Cc :♦ ^C E N [2 Center. Jt Jg tfygnd all comparifon ftronger. The ^reat elevation • is partly the reafon of this. But the diiijofilion of the timbers is alfo much move advantageous, and may be copied even in the low pitched arches of Ncuilly. The fimple tvufs, reaching from pier to pier for the middle point of the arch, gives the ihong fupport where it is moft of all wanted ; and in the lateral points H, al- though one leg of the trufs is very oblique, the other compenfates for it by its upright pofilion. The chief peculiarity of this centre is to be feen in its bafe. This demands a more particular attention : but we muft firlt make fome obfervacions on the condi- tion of an arch, as it reits on the centering after the keyftones are all fet, and on the gradual trjnsferenee of the preffure from the boards of the centering to the joints of the archftones. '< While all the archftones lie on the centering, the - "^T^".^. lower courfes are alfo leaning pretty ftrongly on each ftaeofan Other. But the mortar is hardly comprelled in the arch as it joints ; and leaft of all in the joints near the crown, refts on the Suppofe the arch to be catenarian, or of any other ceiueriDg. ^^p^, j|jj,(, jg pej-ftftly equilibrated : When the center- ing is gradually withdrawn, all the ^chftones follow it. Their wedge-like form makes this impoffible, without the middle ones fqueezing the lateral ones afide.' This comprelFes the mortar between them. As the ftones thus come nearer to each other, thofe near the crown muft defcend more than thoie near the haunches, be- fore every ftone has leflened its diftance from the next by tlie fame quantity ; for example, by the hundredth part of an inch. This circumftance aloiie muft caufe a finking in the crown, and a change of (hape. But the joints near the crown are already more open than thofe near the haunches. This produces a ftill greater change of form before all is fettled. Some mafons endeavour to remedy, or at leaft to diminifh, this, by ufing no mortar in the joints near the crown. They lay the ftones dry, and even force them together by wedges and blocks laid between the ftones on oppofite fides of the crown : They afterwards pour in fine cement. This appears a good praftice. Perroijet rejefts it, becaufe the wedging fometimes breaks the ftones. We (hould not think this any great harm ; becaufe the frafture will make them clofe where they would otherwife lie hollow. But, after all our care, there is ftill a linking of the crown of the arch. By gradually withdrawing the centering, the joints clofe, the archftones begin to butt on each other, and to force afide the lateral courfes. This abutment gradually increafing, the preffure on the haunches of the centering is gradually dimliiifhed by the mutual abutment, and ceafes entirely in that courfe, which is the loweft that formerly prefled it : it then ceafes in the courfe above, and then in the third, and fo on. And, in this manner, not only the centering quits the arch, gradually, from the bottom to the top, hy its own retiring from it, but the arch alfo quits the centenng l/y changing itsjhape. If the centering were row puihed up again, it would touch the arch firft at the crown ; and it muft lift up that part gradually be- fore it come again in contaft with the haunches. It is evident, therefore, that an arch, built on a centre of a fiiape perfeftly fuited to equilibration, will not be in equilibrio when the centering is removed. It is there- fore neceffary to form the centering in fuch a manner {by raifing the crown), that it ftiall leave the arch of 25 A delicate 02 ] C E N a proper form. Tfiis is a very delicate tafl{, requiring Center, a previous knowledge of the enfuing change of form. '— v-— This cannot be afcertained by the help of any theory we are acquainted with. But, fuppofe this attained, there is another difficulty: While the work advances, the centering is warped by the load laid on it, and continually increafing on each fide. The firll preffure on ^he centering forces down the haunches, and raifes the crown. Tlie arch is there- fore lefs curved at the haunches than is intended : the joints, however, accommodate themfelves to this form, and are clofe, and filled with mortar. When the ma- fons approach the middle of the arch, the frame finks there, and rifes up at the haunches. This opens all the joints in that place pn the upper fide. By the time that the keyftones are fet, this warping has gone farther ; and joints are opened on the under fide near the crown. It is true we are here fpeaking rather of an extreme cafe, when the centering is very flexible ; but this oc- curred to Mr Perronet in the two great bridges of Neu- illy and of Mantz. In this laft one, the crown funk above a foot before the key was fet, and the joints at the haunches opened above an inch above, while lome near- er the crown opened near a quarter of an inch beloiu. In this condition of things, it is a delicate buGnefs to (,*,(;„ j'fsTo ftrike the centering. Were it removed in an inftant, all ftrike ihe_ would probably come down ; for the archftones are not'^2""f'''g' yet abutting on each other, and the joints in the middle are open below. Mr Perronet's method appears to us to be very judicious. He began to detach the center- ing at the very bottom, on each fide equally, where the preffure on the centering is very flight. He cut away the blocks which were immediately under each arch- ftone. He proceeded gradually upwards in this way with fome fpeed, till all was detached that had been put out of (liape by the bending of the centering. This be- ing no longer fu])ported, funk inward, till it was flopped by the abutment which it found on the archftones near the crown, which were ftill refting on their blocks. During part of this procels, the open joints opened ftill more, and looked alarming. Tliis was owing to the re- moval of the load from the haunches of the centenng. This allowed the crown to fink ftill more, by forcing out the arch ftones at the haunches. He now pauled fome days; and during this time the two haunches, now hanging in the air, gradually preffed in toward the cen- tering, their outer joints clofing in the meanwhile. The haunches were now prefling pretty hard on the arch- ftones nearer the crown. He then proceeded more flowly, deftroying the blocks and bridgings of thele up- per archftones. As foon as he deftroyed the fupport of one, it immediately yielded to the preffure of the haunch; and if the joint between it and the one adjoining to- ward the crown happened to be open, whether on the under or the uj'perfide, it immediately clofed on it. But in proceeding thus, he found every ftone fink a little while it clofed on its neighbour ; and this was like to produce a ragged foffet, which is a deformity. He therefore did not allow them to fink fo much. In the places of the blocks and bridgings which he had cut away, he fet fmall billets, ftanding on their ends, between the centering and the archftones. Thefe allowed the pen- dulous arch to pufli toward the crown without fenfibly defcending ; for the billets were puftied out of the per- pendicular, and fome of them tumbled down. Proceed- ing C E N [a ing in this way, he advanced to the very next courfe to the keyllone on each fide, the joints cloliii^ all the way as he advanced. The lalt job was very tioublefome ; we mean the detaching the three uppernioll courfes from the centering : for the whole elalllcity of the center- ing was now trying to unbend, and preifing hard againil them. He found that they were litted up ; for the joints beyond them, which had doled completely, now opened again below ; but this job was linilhed in one day, and the centre fprung up two or three inches, and the whole arch funk about fix inches. This was an anxious time ; for he dreaded the great momentum of fuch a vaft mafs of matter. It was hard to fay where it would Hop. He had the pleafure to fee that it Hop- ped very foon, fettling (lowly as the mortar was coni- prcd'ed, and after one or two days fettling no more. This fettling was very confiderable both in the bridge at Neuilly and U^ that at Mantz. In the former, the finking during the work -amounted to 13 inches. It funk fix inches more when the blocks and bridgings were taken out, and i-J- when the little ilandards were deftroyed, and i^ more next day ; fo that the whole fink- ing of \\\t pendulous arch was g-J- inches, befides what it had iunk by the bending and compreflion of the center- ing. The crown of the centering was an arch of a circle defcribed with a radius of 150 feet ; but by the finking of the arch its (hape was confiderably changed, and about fio feet of it formed an arch of a circle whofe radius was 244 feet. Hence Mr Perronet infers, that a ftmicircle of joo feet fpan may be ereiited. It would no douljt be ftronger than this arch, becaufe its greater horizontal thrull would keep the ftones firmer together. The finking of the arches at Mantz was not quite fo great, but every thing proceeded in the fame way. It amounted in all to 23 J- inches, of which 12 inches were owing to the compreflion and bending of the center- ing- In fig. y. n° I. mav be obferved an indication of this procedure of the mafonry. There may be noticed a horizontal line a c, and a diagonal a b. Thefe are fup- pofed to be drawn on the mafonry as it would have flood had the frames not yielded during the building. The dotted line A^' c (hews the (liape which it took by the finking of the centering. The dotted line on the other fide was aftuallv drawn on the malonry when the keyftone was fet ; and the wavy black line on the fame fide (liews the form which the dotted line took by the ftriking of the centering. The undulated part of this line cuts its former pofition a little below the middle, going without it below, and falling within it above. This (hews very diftindly the movement of the whole mafonry, diftinguifhing the parts that were forced out and the parts which funk inward. We prefume that the praAlcal reader will think this account of the internal movements of a (lupendous arch very inftruftlve and ufeful. As Mr Perronet obferved It to be uniformly the fame in feveral very large arches ■which he erefted, we may conclude that it is the gene- ral procefs of nature. We by no means have the con- fidence in the durability or folidity of his arches which he prudently profelTes to have. We have converfed with fome very experienced mafons, who have alfo erefted very great arches, and in very difficult fituations, which have given univerfal fatisfaftion ; and we have found o.'5 ] C E N them uniformly of opinion, that nn arch whicli has fet- Center. tied to fuch a proportion of Its curvature as to change '— -Y— the radius from 150 to 244 feet. Is in a very hazardous fituation. They think the hazard the greater, becaufe the fpan of the aich is fo great in proportion to ita weight (as they cxpiefs it very emphatically) or its height. The weight, fay they, of the haunches is too fmall tor forcing together the keylhwes, which have fcarccly any vvedge like form to keep them from Aiding down. This is very good rcafoning, and expreffes very familiar notions'. The mechanician would fay, that the horizontal thruft at the crown Is too fmall. When we quellioned them about the propriety of Mr Perronet'* method of removing the centering, they unanimoufly approved of its general principle, but fiiid that It was very tlckhfli indeed In the execution. The cafes which he narrates were new to them. They fiiould have al- moil dcfpalred of fuccefs with arches wiiich had gone fo much out of (liape by the bending of the centres ; be- caufe, faid they, the (lope of the centering, to a great diftance from the crown, was fo little, that the arch- fl;ones could not (lide outwards along It, to clofe even the under fide of the joints which had opened above the haunches ; fo that all the archftones were at too great a dillance from each other ; and a great and gene^ ral fubfiding of the whole was necelfary for bringing them even to touch each other. They had never obfer- ved fuch bendings of the centerings which they had em- ployed, having never allowed themfelves to contraft the feet of their trulfes into fuch narrow fpaces. Thev ob- ferved, that nothing but lighters with their malls down can pafs under the trulTes, and that the fides iniift he {t3 proteded by advanced works from the accidental (hock of a loaded boat, that there cannot be left room for more than one. They added, that the bridges of com- munication, necefi'aiyfor the expeditious conduftlng of the work, made all this fuppofcd roomincfs ufelefs :°be- fides, the bufinefs can hardly be fo urgent and crowded anywhere, as to make the palfagc through every arch in- dil'penfably neceflary. Nor was the inconvenience of this obllruftion greatly complained of during the erec- tion of Wellminlter or Blackfrlars bridges. Nothing (hould come in competition with the undoubted folidity of the centering and the future arch ; and all boalting dllplay of talent and Ingenuity by an engineer, in the exhibition of the wonders of his art, is mifplaced here. Thele appeared to us good reafons for preferring the more cautious, and incomparably more fecure, conllruc- tion of Mr Mylne, in which the breadth given to each bafe of the truifes permitted a much more cffeftlve dif- pofition of the abutting timbers, and alfo enabled the engineer to make It incomparably ftlffer ; fo that no change need be apprehended in the joints which have already doled, and in which the mortar has already ta- ken its fet, and commenced an union that never can be reilored if it be once broken In the fmalleft degree, no not even by greater compreffion. Here we beg leave to mention our notions of the- ' connexion that is formed by mortar compofed of lime pefli,,, or gypfum. We confider it as confilling chiefly, if notJhaVi'^' folely, in a cryRalllzation of the lime or gypfum and formed water. As much water is taken up as is neceflfary for*"^' !"<"■'»' the formation of the cryftals during their gradual con-^^'"' verfion into mild calcareous earth or alabafter, and the reft evaporntes. When the free accefs of air is abfo. C c 2 lutely 7 con- ion mie, C E N [ 204 ] C E N Center, lutely prevented, the crylluUizatlon never proceeds to I that ilatf, even although the mortar becomes extremely dry and hard. We had an opportunity of obferving this accidentally, when palTing through Maellricht in J 7 70, while they were cutting up a mafly revftment of a part of the fortifications more than 300 years old. The mortar between the bricks was harder than the bricks (which were Dutch clinkers, fuch as are now iiied only for the greateft loads) ; but when mixed with water it made it lime water, fecmlngly as ftrrong as if frefli lime had been ufcd. We obfervcd the fame thing in one fmall part of a huge mafs of ancient Roman work near Romney in Kent ; but the reft, and all the inry old mortar that we have feen, was in a mild ftate, and vas generally much harder than what produced any lime-water. New when the mortar in the joints has begun its fir!\ cryftallization, and is allowed to remain in perfcdt reit, we are confident that the fubfequent cry- ftals, whether of lime, or of calcareous earth, or of gyp- fum, will be much larger and ftronger than can ever be produced if they are once broken ; and the farther that this cryftallization has been carried, that is, the harder that the mortar has become, Icfs of it remains to take any new cryftallization. Why fhould it be otherwife here than in every other cryflallization that we are ac- 18 quaintcd with ? Neccffity ol We think therefore that it is of great confequence _kfep:ngthej^ keep the joints in iheir Jrj} ftale if poffible ; and ihcVfirft tli!>t the ftrength (as far as it depends on the mortar) ftate. is greatly diminiihed by their opening; efpecially when the mortar has acquired confiderable hardnefs, which it will do in a month or fix weeks, if it be good. The cohefion given by mortar is indeed a mere trifle, when oppofed to a force which tends to open the joints, adt- ing, as it generally does, with the traniverfe force of a lever : but in fituations where the overload on any par- ticular archftones tends to pulh them down through be- tween their neighbours, like wedges, the cohefiun of the mortar is then of very great confequence. We muft make another obfervation. Mr Perronet's ingenious procefs tended very effcftually to clofe the joints. It doing this, the forces which he brought in- to aftion had little to oppofe them ; but as foon as they were clofed, the contaiSt of the parts formerly open op- pofed an obftrudtion incomparably greater, and imme- diatrly balanced a force which was but juft able to turn the ftone gently about the two edges in which it touch- ed the adjoining ftones. This is an important remark, though feemingiy very trifling ; and we wifli the prac- titioner to have a very clear conception of it ; but it would take a multitude of words to explain it. It is worth an experiment. Form a little arch of wooden blocks ; and form one of thcfe fo, that when they are all refting on the centering, it may be open at the outer joint — Remove the centering — Then prefs on the arch at fome diftance from the open joint. — You will find that a very fmall prefTure wUl make the arch bend till that joint clofes. — Prefs a little harder, and the arch will bend more, and the next joint will open. — Thus you will find that, by prefling alternately on each fide of the open joint, that ftone can ealily be made to flap over to either fide ; and that immediately after this is done the refiilance increafes greatly. This fiiews clearly, that a very moderate force, judicloufly employed, will clofe the joints, but will not prefs tie parts ftrongly toge- ther. The joints therefore are clofed, but no more than Center. clofed, and are hanging only by the edges by which they *-"-»—— ' were hanging while the joints were open. The arch, thcicfore, though apparently clofe and firm, is but loofe and tottering. Mr Perronet fays, that his arches were firm, becauie hardly a ftone was obfervcd to chip or fplinter off at the edges by the fettlement. But he had done every thlEig to prevent this, by digging out the mortar from between the headere, to the depth of two inches, with faws made on purpofe. But we are well informed, that before the year 1791 (twent)- years af- ter the eredtion) the arches at Ncuilly had funk very fenfibly, and that very large fplinters had flewn off in . feveral places. It could not be otherwife. The oiigi- Mr Perro- nal conllruftion was too bold ; we may fay needlcfsly net's con- and oftentatioufiy bold. A very gentle (lope of the '^'■"^'°°' roadway, which would not have flackened the mad gal- lop of a ducal carriage, nor fenfibly checked the labo- rious pull of a loaded waggon, and a proper dliference in the fize of the arches, would have made this won- derful bridge incomparably ftronger and alfo much more elegant and pleafiug to the eye. Indeed, it is far from being as handfome as it might have been. The eUipfe is a moft pleafing figure to every beholder ; but this is concealed as much as poffible, and it is attempt- ed to give the whole the appearance of a tremendous lintel. It has the oppreffive look ot danger. It will not be of long duration. The bridge at Mantz is ftill more exceptionable, becaufe its piers are tall and /lender. If any one of the arches fails, the reft muft fall in a moment. An arch of Blackfriars Bridge might be blown up without difturbing its neighbours. ^ Mr Perronet mentions another mode of ftriking the A bad me. centering, which he fays is very ufual in France. Every thod of fecond bridging is cut out. Some time after, every fe- "■'''""g '"* cond of the remainder ; after this, every fecond of the remainder ; and fo on, till all are removed. This is ne- ver prattifed in this country, and is certainly a very bad method. It leaves the arch hanging by a number of di- ttant points ; and it is wondertul that any arch can bear this treatment. Our architedts have generally proceeded with extreme cautioni Wherever they could, they fupported the cen- tering by intermediate pillars, even when it was a trufTed centre, having a tie-beam reaching from fide to fide. The centre was made to reft, not immediately on t^c'^xhe o pillars, but on pieces of timber formed like acute wedges, nion me- placed in pairs, one above the other, and having thethodin point of the one on the thick end of the other. Thcfe J*"'^'- wedges were well foaped and rubbed with black lead, to make them flippery. When the centres are to be ftruck, men are Rationed at each pair of the wedges with heavy malls. They are diredled to ftrike together on the op- pofite wedges. By this operation, the whole centering deicends together ; or, when any part of the arch is ob- fervcd to have opened its joints on the upper fide, the wedges below that part are flackened. The framing may perhaps bend a little, and allow that part to fub- fide. If any part of the arch is obfervcd to open its joints on the under fide, the wedges below that part are allowed to ftand after the reft have been flackened. By this procefs, the whole comes down gradually, and as flowly as we pleafe, and the deiedls of every part of the arch maybe attended to. Indeed the caution and mo- deration of our builders have commonly beea fbcb, that few C E N Center, few defc..!^s have been allowed to fhew themfelves. Wl • are but little acquainted with joints opening to the ex- tent of two inches, and in futU a caie would probably lift every ilone of the arch a^ain (b). We have not employed trufled centerings lo much perhaps as we ihould have done ; nor do we fee their advantage (fpeak- ing as mere builders) over centres fupported all over, and unchangeable in their form. Such centres mull bend a little, and require loading on the middle to keep them in fliape. Their compreliion and their elallicity, are very troublelbme in the ilriking of the centres in Mr Perronel's manner. The elallicity is indeed of ufe when the centres are ftruck in the way now delcribed. Theie obfervations on the management of the inter- nal movements of a great arch will enable the reader to appreciate all the merit of Mr Mylne's very ingenious conftruilion. We proceed therefore to complete our ilefcription. The gradual enlargement of the bafe of the piers of Blackfriars bridge enabled the architedl to place a feries of five polls c, c, c, c, c, one on each flap of the pier ; the ingenious contexture of which made it like one fo- _, ^* , lid block of (lone (fee Arch, Supplement). Tliefe Itruts fnjj gfj^jj. were gradually more and more oblique, till the outer Vlylne's one formed an obtufe angle with tlie lowcil fide of the nethod. interior polygon of the truls. On the top of thefe polls was laid a floping seat or beam D of llout oak, the up- per part of which was formed like a zig-zag Icarfing. The polls were not perpendicular to the under fide of the feat. The angles next the pier were fomewhat ob- tufe. Short pieces of wood were placed between the heads of the polls (but not mortifed into them), to pre- vent them from flipping back. Each face of the fcarf was covered with a thick and fmooth plate of copper. The feet of the tnifs were mortifed into a iimilar piece F, which may be called the sole of the trufs, having its lower fide notched in the fame manner with the up- per fide of D, and like it covered with copper. Ee- tween thefe two lay the striking wedge L,, the faces of which correfponded exadtly with the flant faces of the feat and the fole. The wedge was fo placed, that the correfponding faces touched each other for about half of their length. A block of wood was put in at the broad end or bafe of this wedge, to keep it from flipping back during the laying the arch-llones. Its outer end E was hound with iron, and had an iron bolt feveral inches long driven into it. The head of this bolt was broad enough to cover the whole wood of the wedge within the iron ferule. We prcfume that the reader, by this time, forefees the ufe of this wedge. It is to be driven in between the fole and the feat (having firil taken out the block at the bafe of the wedge). As it advances into the wider fpaces, the whole trufs mull defcend, and be freed from the arch ; but it will require prodigious blows to drive it back. Mr Mylne did not tliink fo, founding [ 20J ] C E N his expeflation on what he faw in the launching of great Center, ftiips, which Hide very eafily on a fiope of lo or 12 de- *— v— ^• grees. He rather feared, that taking out the block behind would allow the wedge to be pullied back at once, fo that the defcent of the trufs would be too ra- pid. However, to be certain of the operation, he had prepared an abundant force in a very ingenious manner. A heavy beam of oak, armed at the end with iron, was lufpended from two points of the centre like a battering ram, to be ufcd in the fame manner. Nothing could be more fimple in its ftrufture, more powerful in its operation, or more eafy in its management. Accord- ingly the fuccefs was to his wifli. The wedge did not flip back of itfelf ; and very moderate blows of the ram drove it back with the greateR eafe. The whole ope- ration was over in a very few minutes. The fpeftators had fufpedled, that the fpace allowed for the re?efs of the wedge was not fufficient for the fettlement of the arch ; but the architeft truHed to the precautions he had taken in its conllruftion. The reader, by turning'- to the article Arch in this Supplement, will fee that there was only the arch LY which could be expefted to fettle : accordingly, the recefs of the wedge was found to be much muie than was necelTary. However, had this not been the cafe, it was only neceflary to take out the pieces between the polls below the feat, and then to drive back the heads of the flruts ; but this was not needed (we believe) in any of the arches. We are well allured that none of the arches funk an inch and a half. The great arch of 100 feet fpan did not fink one inch at the crown. It could hardly be perceived whe- ther the arcli quitted the centering gradually or not, fo imall had been the changes of fhape. We have no hefitation in faying, that (if we except The'Vrcat fomc wafte of great timber by uncommon joggling) thefnpcriority" whole of this performance is the moll perfect of any"' 'f": "n- that has come to our knowledge. We doubt not butjf '^f^"*^*^' that feveral have equalled it, or may have excelled it j ^ but we do not know of them : and we think that the bringing forward fuch performances is no lefs fcrvicc- able to the public, than it is honourable to the inventor. Nor do we luppofe that any views of interefl can ht fo powerful as to prevent ;ui ingenious architedt from com- municating to the public iueh honourable fpttimens of his own talenls. We lliould be iiappy to communicate more of this kind ; for we confider it as a very import- ant article of praftlcal mechanics, and think that it is of confcquence to the nation that it fliould be very ge- nerally underltood. In every corner of the country bridges arc to be built — wc have everywhere good ma- fins, v/ho are fully able to execute any prafticable pro- je6t, but too little acquainted with principle to invent, . or to accommodate even what they know to local cir- cumftanccs, and are very apt to be duped by appear- ances of ingenuity, or milled by erroneous notions of the ilrains which are. excited. We profefs more fcience, and (b) The writer of this article can only fay, that, after much inquiry, he has no information of any arch being received from the builder as fufficient that had fuifered half the charge of fliape mentioned by Mr Terrouct. The arch of Dublin bridge, built by an excellent, but a very private, niafon, Mr Steeven, is 105 feet wide, with ■ only 22 feet of rife. It was eretled (but not on a truffed centering) without changing one full inch in its ele- vation ; and when the centering was removed, it funk only i|th inches, aud about half an inch ir.ote whec the parapets were added and the bridge completely finifhed. C E E [20 ^ Cen tny and to treat the fubjeft with the alTiftance of accurate * principles : But while we are certain that every cir- cumftance is ful'ccptible of flie moll accurate determi- nation, we mull acknowledge that we have by no means attained an accurate knowledge of all the ftrains which are produced and excited in a frame of carpentry, which is fettling and changing its fiiape, even though it be not very cumplicated ; far lefs are we pofTefied of a clear view of wliat happens in a mafs of mafonry in fimilar conditions. Therefore, though we fpeak with the flrong belief of our being right, we fpeak with a fenfe of our fallil.ility, and with great deference to the judgment of eminent and experienced architedls and engineers. We fhould . conlider their free and candid criticifms as the highell favour ; and we even folicit them, with affuran- ces of llianks, and that we will take fome opportunity, before the clofe of this work, to acknowledge and cor- reft our miilakes. We even prefume to hope, that the libcral-mindtd arlift will be pleafed with this opportu- nity which we give him of increaling the national (lock of knowledge. Let mutual jealoufy and rivallhip reign in the breafts, and prompt the exertions, of our reftlefs neighbours on the continent— let them think that the dignity of man confids In perpetual warfare, in which every individual feels himfelf indebted only to liimtclf, freed from all the fwect ti;s of domeftic partiality, of fricndlhip, and of patriotic attachment. We hope that thf hearts of Britons will long continue to be warmed and forlifirdhv the thoughts of mutual affiilance, mu- tual co-operation, mutual attachment, and a patriotic preference of their countrymen to all other men. While thefe fentiments are regulated by unfhaken honeily, by candour, and by Chriltian charity, we fliall be fecurcd from the errors of partial attachments, and yet enjoy all the pleafures of unfophifticated nature. Families will ftill be bound together by the affectionate ties of blood; and the whole frame of Britifli fociety will be in har- mony with the bonds which connefl the members of each family, by their endlefs croffings and intermi.\ings. In tin's ilalc, the (late of focial nature, the man of ta- lents will not lock up all the fruits of his exertions in his own brealt, but will feel a pleafure in imparting them to a fociety that is dear to him, and on which he depends for all his bell enjoyments. Nothing will hold the good man back when this is in his power, but the virtuous ufe which he can make of his fuperiority in the difcharge of his own little circle of duties. This is all that is required of true patriotifm ; and it is not too much to be cxpefted from Britons, who feel a pleafure in viewing their country as the great fchool of the arts, under the patronage of a fovereign who has done more for their improvement than all the other princes of Eu- rope, and who (we are well affured) is now meditating a plan which mult be highly gratifying to every emi- nent profeffor of the aits. _, 3^, The fubjeft which we have been confnlering is very ■ie b' from one end to the other, and make them two t-hoj'. fhefe iiffc- feparate fran>es. Whenever this cannot be done with- rent me. out that part opening, it is a conflruftion by compofi- tion. Some of the beams are on the ilretch ; and iron ilraps, extending along both pieces, are neceffary for fe- curing the joint. The bridge is no longer a piece of matonry, but a performance of pure carpentry, depend- ing on principles peculiar to that art. Equilibration is •tieceffary in the firft conftruftion ; but, in the fecond, any inequality of loading is made ineffectual for hurt- ing the edifice, by n\eans of the (Iretch that is made to operate on fome other piece. We are of opinion, that this mofl fimple employment of the diftinguiffiing principle of carpentry, by which the beams are made to aft as ties, will give the moft perfeft conftruftion of a wide bridge. One polygon alone fhould contain the whole of the abutments ; and one other polygon .*hould confill entirely of ties; and the beams which form the radii, conneding the angks*of the two poly- gons, complete the whole. By confining the attcn- SufPL. Vol. I, Part I. 09 ] C E N tion to thefe two fimple obj-fts, the abutments of th« Cemrr. outer polygon, and the joints of the inner one, may l)c — -v— formed in the motl fimple and efficient minner, without any collateral connections and depcrtdenci-s, which di- vide the attention, increafe the complication, and com- monly produce unexpected and hurtful ftrains. It was for this reafon that we have fo frequently recommended the centering of the bridge of Orleans. Its office will be completely performed by a trufs of the form of fig. 23. ; where the polygon ABCDEF, confifting of two layers of beams (if one is not fufikient), contains the whole abutments, and the other Ai^-^f F is nothing but an iron rod. In this conflruftion, the obtufeiiefs of the angles of the lower polygon is rather an advan- tage. The braces G c , G - P water below it, raife it on it, and bear it away. The 2. If a lighted taper be let down into ajar of oxgen <;j JJ , difh muft be allowed to retain a quantity of water in it, gas, it burns with fiich fpltndor that the eye can fearcc-flamc (fee fig. 2.) Another jar may then be filled with air ly bear the glare of light, and at the fume time time pio- in the fame manner ; and this procefs may be continued duces a much greater heat than when burning in com- cither till the nitre ceafcs to give out air, or till as many mon air. It is well known that a candle put into a well jarfuls have been obtained as are required. This me- clofed jar, filled with common air, is extinguifhed in a thoil of obtaining and confining air was firil invented few feconds. This is the cafe alfo with a candle enclo- bv Dr Mayow, and afterwards much improved by Dr fed in oxygen gas ; but it burns much longer in an equal Hales. All the airs obtained by this or any other quantity of that gas than of conuiion air. ic r procefs, or, to fpeak more properly, all the airs differ- 3. It was proved long ago by Boyle, that animals can- And life, ing from the air of the atmofphere, have, in order to di- not live without air, and by Mayow that they cannot ftinguifli them from it, been called gafis, and this name breathe the fame air for any length of time without fuf- ^ we fhall afterwards employ. focation. Dr Prieftley and fcvcral other philofophers SIfcovered 1'he gas which we have obtained by the above pro- have fhewn us, that animals live much longer in the by f ricftlcy cefs was difcovered by Dr Prieftley on the irtof Au- fame quantity of oxygen gas than of common air. »ndScheele,gu(l 1774, and called by him dephlo_(ifltcated air. Mr Count Morozzo placed a number of fparrows, one after Scheele of Sweden difcovered it in 1775, without any another, in a glafs bell filled with common air, and in- verted over water. h. M. The firft fparrow lived - - 30 The fecond - • - - 03 The third ....01 He filled the fame glafs with oxygen gas, and re- peated the experiment. The firft fparrow lived The fecond The third The fourth The fifth The fixth The feventh The eighth The ninth The tenth H. M. J 23 2 10 I 30 I 10 30 47 27 .^0 22 21 previous knowledge of what Dr Prieftley had done : he gave it the name of empyreal air. Condorcet, fo con- fpicuous during the French revolution, gave it firft the name of -uiial air ; and Mr Lavoifier afterwards called it oxygen gas ; a name which is now generally received, and which we fhall adopt. Oxygen gas may be obtained likewife by the follow- ing procefs : D (in fig. 3.) reprefents a wooden trovigh, the infide of which is lined with lead or tinned copper. AB is a flielf running along the infide of it, about three inches from the top. C is the cavity of the trough, which ought to be a foot deep. It is to be filled with water at leaft an inch above the fhelf AB. In the body of the trough, which may be called the ciftern, the jars deftined to hold gas are to be filled with water, and then to be lifted, and placed inverted upon the (lielf at B, He then put in two together ; the one died in 20 mi- with their edges a little over it. This trough, which was nutes, but the other lived an hour longer. rr invented by Dr Prieftley, has been called by the French 4. Atmofpherical air contains abuut 27 parts in the^''''^'' '•"' chemifts iht pneumato-chcmicnl, or fimpiy ^«^ama/;V appa- hundred of oxygen gas. This was firft dilcovered by ^.'^ a'uw. ratus, and is extremely ufeful in all experiments in which Sciiecle. It has been proved by a great number cf ex- gafes are concerned. Into the glafs veftll E put a quan- periments, that no fubftance will burn in common air tity of the black oxide (a) of manganefe in powder, and previoufly deprived of all the oxygen gas which it coi\- jjour over it as much of that liquid which in commerce tained ; but combuftibles burn with great fplendor in is called oil of vitriol, and in chemiftry fulphuric acid, as oxygen gas, or in other gafes to which oxygen cfas has will lomewhat more than cover it. Then infert into been added. Oxygen gas- then is abfolutely nectlTary the mouth of the velTel llie glafs tube F, fo clofely that for combuftion. no air can efcape except through the tube. This may 5. It has !)een proved alfo, by many experiments, that be done by covering the joining with a parte m;ide of no breathing animal can live fur a moment in any air or ' wheat-flour and water, or any other /u/c, as fubftances gas which doe;; not contain oxygen mixed with it. Oxy- iifed for fimilar purpofes are called. The end of the gen gas then is abfolutely neceffary for refpiration. tube C is then to be plunged into the pneumatic appa- 6. When fubftances are burnt in oxygen gas, or iri , ratus D, and the jar G, previoufly filled with water, to any other gas containing oxygen, if the air be examined be placed over it on the llielf. The whole apparatus be- after the combuftion, a great pat-t cf the oxygen will he ing fixed in that fituation, the glafs veffel E is to be found to have difappeared. If charcoal, for inftance, heated by means of a lamp or a candle. A great quan- be burnt in oxygen gas, there will be found, inilcad of tity of oxygen gas rulhes along the tub F, and fills the part of the oxygen, another very dift'erent gas, known by- jar G. As foon as the jar is filled, it may be Aid to an- the name of carbonic acid gas. Exaftly tlie fame thini'- other part of the flielf, and other jars fubftituted in its takes place when air is refpired by animals ; part of the place, till as much gas has been obtained as is wanted. oxygen gas difappears, and its place is occupied bv fub- I. Oxygen gas is colourlefs, and invifible like com- ftances pofTefTed of very dill'ereiit properties. Oxygen gas (a) This fubflance fhall be afterwards defcribed. ufe with bleachers and feveral other manufafturers. It is now very well known in En'tai.n, as it is in comm.on CHEMISTRY. Part h la Its f)hnr is capable of cryllallizing. If it be melted, and as foon as its furface begins to congeal, the li.jnid fulphur beneath be jioured out, the internal cavity will exhibit long needle-lhapcd cryllals of an oc- tahedral figure. This method of cryl'ialliiing fulphur was contiived by Rouelle. When fulphur is heated to the temperature of 3 02° Converted In the open air, it takes fire fpontaneoufly, and burns by combuf- with a pale blue fl.ime, and at the fame time emits a""" '"'°^ great quantity of fumes of a very ftrong fuffocating odour. When heated to the temperature of 370°, or a little higher, it burns with a bright white flame, and at the fame time emits a valt quantity of fumes. If the heat be continued long enough, the fulphur burns all away without leaving any afhes or rcfiduum. If the fumes be collefted, they are found to confift: entirely of fulphuric add. By combuilion, then, fulphur is con- verted into an acid. This faft was known feveral cen- turies ago, but no intelligible explanation was given of it till the time of Stahl. That chemill undertook the ta(]<; and founded on his experiments a theory fo exceeding- ly ingenious, and fupported by fuch a vail number of fafts, that it was in a very (hort time adopted with ad- miration by all the philolophic world, and contributed not a little to raife chemiilry to that rank among the fciences from which the ridiculous pretenfions of the early chemills had excluded it. ,, According to Stahl, there is only one fubftance in Stahl's cs— nature capable of combuftion, which therefore he called I^j.^",^f'"" Phlogiston ; and all thofe bodies which can be fet on fire contain lefs or more of it. Combuftion is mere- ly the reparation of this fubftance. Thofe bodies which contain none of it are of courfe incombuilible. All com- bnftibles, except thofe which conlill of pure phlogifton (if there be any fuch), are compofed of an incoinbuftbile body and phlogifton united together. During combuf- tion the phlogifton flies ofl^, aiul the incombuftlble body remains behind. Now when fulphur is burnt, the fub- ftance which remains is fulphuric acid, an incoinbuftible body. Sulphur therefore is compofcd of fulphuric acid and phlogifton. To eftablilh tliis theory completely, it was neceffary to ftiew that fulphur could be aftually made by combi- ning fulphuric acid and phlogifton ; and this alfo Stahl undertook to perform. Sulphat of pottfs is a fubftancff compofed of fulphuric acid and potafs (d), and charcoal is a combuftible body, and therefore, according to the theory of Stahl, contains phlogifton : when burnt, it leaves a very inconfiderable relidnum, and confequently contains hardly any thing elfe than phlogifton. He melted together in a crucible a mixture oi polafs ?indful- phat of potafs, Itlrred into it one-fourth part by weight of pounded charcoal, covered the crucible with another inverted over it, and applied a ftrong heat to it. He then allowed it to cool, and examined its contents. The charcoal had difappeared, and there only remained in the crucible a mixture of potafs and fulphur combined together, of this. (d) The nature oi potafs (hall afterwards be explained, purity. It is the potafb well known in commerce in a ftate of 2l6 S;.l[.l'«r together, and of a darker colour than ufual, from the *~~v~— rclidiuim of the charcoal. Now there were only thiec fubftaiiccs in the crucible :it firll, potafs, fulphuric acid, and charcoal : two of thele have difappeared, andy«/- f/.tir has been found in their place. Sulphur then nuift hive been formed by the combination of thefe two. Uut charcoal coiifilbs of phlo;;illon and a very fmall rc- fidunni, which is flill found in the crucible. The ful- CHEMISTRY. fame, there was not the finalleft reafon to fiippofe that any fubftance had left the fulphur.. It is impofiible, then, that fulphur can be compofed of fulphuric acid and phlogiilon, as Stahl fuppofed ; finee fulphur ilfclf enters as a part into the conipofitiotj of that acid. There muft therefore have been foine want of accuracy in the experiment by which Stahl proved the compolition of fulphur, or at leaft fome f-.d- Part I. Sblj-huf. 21 Unfatirfac- tuiy. phnr then mull have been formed by the combination lacy in his reafouings; for it is impoflihle that two con- of fulphuric acid and phlogiilon. This fimple and lu- tradiftory fafts can both be true. Upon examiiring the rr.iiious explanation appeared fo fatisfaftory, that the potafs and fulphur produced by Stahl's experiment, we compofition of fulphur was long confidered as one of tind them to be confiderably lighter than the charcoal, the bell demonilrated truths in chemilhy. fulphuric acid, and potafs originally employed. Some- There are two fai\s, however, which Stahl either did thing therelore has made its efcape during the applica- not know or did not Aifiiciently attend to, neither of tion of the heat. And if the experiment be conduded which were accounted for by his theory. The tirft is, in a clofe veffel, with a pneumatic apparatus attafhed that fulphur will not burn if air be completely exclu- ded ; the fccond, that fulphuric acid is heavier than the fulphur from which it was produced. To account for thefe, or fafts fimilar to thefe, fuc- ceedinop chemifts refined upon the theory of Stahl, de- li R'al rxp!; ration hy I.ivoificr. 43 to it, a quantity of gas will be obtained exactly equal to the weight which the fubftances operated on have loft ; and this weight confiderably exceeds that of all the charcoal employed. This gas is carbonic acid ^as, which is cojTipofed d( charcoal and oxygen, as will af- privedhis phlogiilon of gravity, and even affigned it a terwards appear. We now perceive what pafles in this principle of kvity. Still, however, the neceflity of the experiment : Charcoal has a ilronger affinity for oxygen contadl of air remained unexplained. At lall Mr La- at a high temperature than fulphur has. When char- voifier, who had already difcinguiftied himfelf by the ex- coal therefore is prefented to fulphuric acid in that tenfivenefsof his views, the accuracy of his experiments, temperature, the oxygen of the acid combines with it, and the precifion of his reafoning, undertook the exa- they fly off in the form of carbonic acid gas, and the mination of this fubjcft, and his experiments were pub- fulphur is left behind. liflied in the Memoirs of the Academy of Sciences for The combuftion of fulphur, then, is nothing elfe than '■• 1777. He put a quantity of fulphur into a large glafs the adt of its combination with oxygen j and, for any veflel filled with air, which he inverted into another vef- thing which we know to the contrary, it is a fimple fel containing mercury, and then fet fire to the fulphur fubftance. by means of a burning-glafs. It emitted a blue flame, and gave out thick vapours, but was very foon extin- as follows : l'u)phur. guifhed, and could not be again kindled. There was, however, a little fulphuric acid formed, which was a good deal heavier than the fulphur which had difap- peared ; there was alfo a diminution in the air of the vefTcl proportional to this increafe of weight. The fulphur, therefore, during its converfion into an acid, muft have abforbed part of the air. He then put a quantity of fulphuret of iron, which confifts of fulphur and iron combined together, into a glafs veflfel full of air, which he inverted over water (e). The quantity of air in the velTel continued diminifliing for eighteen days, as was evident from the afcent of the water to occupy the fpace which it had left ; but after that period no farther diminution took place. On examining the fulphuret, it •was found fomewhat heavier than when firft introduced into the veffel, and the air of the veffel wanted precifely the fame weight. Now this air had loft all its oxygen ; all the oxygen of the air in the veffel muft therefore - — 24 have entered into the fulphuret. Part of the fulphur The affinities of fulphur, according to Bergman, are /^fljnjjjjj^j Lead, Tin, Silver, Mercury, Arfenic, Antimony, Iron, Fixed alkalies, Ammonia, Barytes, Lime, Magnefia, Phofphorus ? Oils, Ether, Alcohol. Sect. II. Of Phofphorus. Let a quantity of bones be burnt, or, as it is term-Produilion was converted into fulphuric acid ; and as all the reft of ed in chemiftry, calcined, till they ceafe to fmoke, or "^ P"°'l'"'' the fulphuret was unchanged, the whole of the increafe to give out any odour, and let them afterwards be re- ef weight muft have been owing to fomething which duced to a fine powder. Put this powder into a glafs had entered into that part of the fulphur which was veffel, and pour fulphuric acid on it by httle at a time, converted into acid. This fomething we know was till farther additions do not caufe any extrication of air oxygen. Sulphuric acid therefore muft be compo- bubbles (r). Dilute the mixture with a good deal of fed of fulphur and oxygen ; for as the original weight water, agitate it well, and keep it hot for fome hours j of the whole contents of the veffel remained exaftly the then pafs it through a filter. Evaporate the liquid flowly (e) This experiment was firft made by Scheele, but with a different view. (f) The copious emiffion of air bubbles is called in chemiftry effervefccnce. Part I. C H E M 45 Its dilco- very. Berlin. Phoi", liiriii fliAvly till a quantity of white powdei' f Journal de that is to fay, it fufl'ers a How combullion : fo tlut it ^'hf'}"'' , , ' . r , • ,- 1. 1 • •. • ilOtV. 380, can only be prevented trom taking lire by keeping it in a very low temperature, or by allowing it to remain al- ways plunged in water. If air be excluded, it evapo- rates at 219", and boils at 554*^ f. When heated io^Uid-iit. I22'> f H^, it burns with a very briaht flame, and gives .. '^7 \ ' . r 1 • /■ 1 1 • L ■ 1 • Converted out a great quantity ot white Imoke, which is luminous |, combuf« in the dark; at the fame time it emits an odour which tion has fome refemblance to that of garlic. It leaves no refiduum ; but when the wliitc fmoke is collected, it is found to be an acid. Stahl conlidered this acid as the muriatic (.1). According to him, phofphorus was com- pofed of muriatic acid and phlogillon, and the combuf- tion of it was merely the feparatinn of phlogillon. Pie even declared, that to make phofphorus, nothing more was neceffary than to combine muriatic acid and phlo- gillon ; and that this compofition was as eafily accom- phlhed as that of fulphur itfelff. \ThreeHun. Thefe aflertions gained implicit credit ; and the com- dred Expiri- pofition and nature of phofphorus were confidered as "'"'''• completely underllood, till Margraf of Berlin publidied his experiments in the year 1743- That great man, one of thofe illullrious philofophers who have contribu- ted fo much to the rapid increafe of the fcience, dillin- guilhed equiiUy for the ingenuity of his experiments and the clearnefs of his reafaning, attempted to produce phofphorus by combining together phlogillon and mu- riatic acid ; but though he varied his procefs a thou- fand ways, prefented the acid in many ditferent Hates, and employed a variety ot fubllances to turniih phlogil- ton, all his attempts failed, and he w.hs obliged to give ,g up the combination as impradlicable. On examining Into phof- the acid produced during the combuftion of phofpho- phone acid, rus, he found that its properties were very different trom thofe of muriatic acid. It was therefore a diftinft fub- ftance. The name of pbofphoric acid was given to it ; and it was concluded tliat phofphorus was compofed of this acid united to phlogifton. But it was obferved in 1772 by Morveau J, that § Oifrr/. phofphorlc acid was heavier than the phofphorus from " ""' which it was produced (k); and Boyle had long before (hewn that phofphorus would not burn except when in contaft with air. Thefe fadts were fufficient to prove the inaccuracy of the theory concerning the compofi- tion of phofphorus ; but they remained thenifelves un- accounted tor, till Lavoifier publilhed thofe celebrated experiments, which threw fo much light on the nature and compofition of acids. , He exhaufted a glafs globe of air by means of an air- E e pump ; (g) Crell, in his life of Scheele, informs us that Scheele was himfelf the difcoverer of the fail. This, he fays, clearly appears from a printed letter of Scheele to Gahn, who was before looked upon as the difcoverer. See CreU's yjnnals, Englilh Tranf. I. 17. (h) Morveau, Encyd. Method. Chimie, art AffmUc. — According to Nicholfon at 160". See his TranJlaUon of Chaptal. ( I ) This acid fhall be afterwards defcribed. (k) The fame obfervation bad been made by Margraf, but no attention was paid to it. 2l8 Phofphorus, 19 Which is phofphorc comi-intd ■with oxy- gen. ^L.ii'oifiir. Hbenrjiry, Part I. chap. V. 30 Fhofphorus tor. bine ■with ful- phur. C H E M ■pump ; and after weighmg it accurately, he filled it with oxvgen gas, and iiitrnduced into it ico grains ot phofphorus. The globe was furnifhed with a ftup- cock, bv which oxygen gas could be admitted at plea- lure. He i^et fire to the phofphorus by means of a Lurning-glafs. The combnllion was extremely rapid, accompanied by a bright flame and muclt lieat. Large quantities of white flakes attached thcmfelves to the in- ncr furface of the vlobe, and rendered it opaque ; and thtfe at laH became fo abundant, that notwithllandin;^ the conftant fupply of oxygen gas, the phofphorus was txtinguiflied. The globe, after being allowed to cool, was again weighed before it was opened. The quantity of oxygen employed dniing the experiment was afcer- tained, and the phofphorus, which ilill remained un- changed, accurately weighed. The white flakes, which were nothing tlfe than pure phofphoric acid, were found exaftly equal to the weights of the phofphorus and oxygen, which had difappeared during the procefs. Phofphoric acid therefore niuft have been formed by the combination of thefe two bodies ; for the ablolute weight of all the fubftances together was the fame be- fore and after the procefs *. It is impofuble then that phofphorus can be compofed of phofphoric acid and phlogifton, as phofphorus itfelf enters into the compo- fition of that acid (l). Thus the combuilion of phofphorus, like that of ful- phur, is nothing elfe than its combination with oxygen; for during the procefs no new fubflance appears except the acid, accompanied indeed with much heat and light. Phofphorus combines readily with fulphur, as Mar- graf difcovered during his experiments on phofphorus. This combination was afterwards examined by Mr Pel- letier. The two fubllanccs are capable of being mixed in different proportions. Seventy-two grains of phof- phorus and nine of fulphur, when heated in about four ounces of water, melt with a gentle heat. The com- pound remains fluid till it be cooled down to 77'^, and then becomes folid. Thefe fubftances were combined in the fame manner in the following proportions : 'fiTr^f"''? congeals at 59" 18 Sulphur S ° ■'^ Phofphor.l Sulphur J 72 Phofphor. 1 r J !■>■ 36 at at at 509 99' ■f VtUtiUr, 'Jour, de jehyf. XMV. 381. 72 Sulphur 72 Phofphor. I 216 Sulphur J Phofphorus and fulphur may be combined alfo by melting them together without any water; but the com- bination takes place fo rapidly, that they are apt to rufh out of the veffe! if the heat be not exceedingly mo- derate -j-. Phofphorus is capable of combining alfo with many other bodies : the compounds produced are called phoj- fburtlt. I S T R Y. Parti. The affinities of phofphorus have not yet been afecr- Csrbou. tained. *~~^""""' Sect. III. Of Carbon. If a piece of wood be put into a crucible, well co- vered with faiid, and kept red hot for feme time, it is converted ijito a black ihining brittle fubllance, without either taltc or fmell, well known under the name of charcoal. This fubftance contains always mixed with it icveral eai thy and faline particles. When freed from thefe impurities it is called carbon. Charcoal is infoluble in water. It isnotafiefted (pro- properties vided that all air be excluded) by the moft violent heat of carbon, which can be applied, excepting only that it is lendered much harder. New-made charcoal abforbs moifture with avidity. When heated to a certain temperature, it abforbs air copioufly. La Metherie plunged a piece of burning charcoal into mercury, in order to extinguifli it, and introduced it immediately after into a glafs veffel filled with common air. The charcoal abforbed four times its bulk of air. On plunging the charcoal in water, one-fifth of this air was difengaged. This air, on be- ing examined, was found to contain a much fmaller quantity of oxygen than atmofpherical air does. He extinguilhed another piece of charcoal in the fame man- ner, and then introduced it into a veflel filled with oxy- gen gas. The quantity of oxygen gas abforbed ainount- ed to eight times the bulk of the charcoal ; a fourth part of it was difengaged on plunging the charcoal into water *. It appears from the experiments of Sennebier, *Jcur. dt that charcoal when expofed to the atmofphere abforbs ^AV- ^^^t- oxygen gas in preterence to a%oi \, as the other portion J°9 of common air is called. f;^,-,^ '-^ When heated to the temperature of 370° |, it takes i6i. fire, and, provided it has been previoufly freed from the t Moriicai, earths and ialts which it generally contains, it burns ^'O''- ^'- without leaving any refiduum. If this combuftion be dir^-fi ' performed in clofe veffels filled with oxygen gas inftead ^2 of common air, part of the charcoal and oxygen difap- Converted pear, and in their room is found a particular gas exaftly "?'° ^^ '* equal to them in weight. This gas has the properties'"' of an acid, and is therefore called carbonic acid gas. Mr Lavoifier, to whom we are indebted fur this difcovery, afcertained, by a number of very accurate experiments, that this gas was compofed of about 28 parts of carbon and 72 of oxygen ||. || M,m. A. Carbon is fufceptible of cryftallization. In that ftatc <■"'''• 1781, it is called diamond. The figure of the diamond varies ^' ^''^" confiderably ; but moft commonly it is a hexagonal prifm Sufceptilde terminated by a iix-fided pyramid. When pure it is co- of cryftalli- lourlefs and tranfparent. Its fpecific gravity i» from nation. 3,44 to 3,55. It is one of the hardeft fubftances in nature ; and as it is not aflefted by a confiderable heat, it was for m.any ages confidered as incombuftible. Sir Ifaac Newton, obferving that combuftibles refrafted " light more powerfully than other bodies, and that the diamond poflefled this property in great perfeftion, fuf- pe£le4s (l) The quantity of phofphorus confumed was 45 grains The quantity of oxygen gas ... 69,375 Weight of the phofphoric acid produced 1 14,375 Phofphoric acid therefore is compofed of 100 parts phofphorus and 1.54 oxygerb CHEMISTRY. pcdid, from that circumftanct, tliat it was capable of cciribiiftion. This lingular coiijidlure was verified in 1 f)94 by the Florentine academicians, in the prtfence of Cofnio III. grand duke of Tufcany. By means of a burnlng-glafs, tliey deftroyed ftviral diamonds. Fran- cis I. emperor of Germany, afterwards witncfTed the de- flrudlion of feveral more in the heat of a furnace. Thefe experiments were repeated by Rouelle, Macquer, and D'Arcet ; who proved that the diamond was not merely evaporated, but aftually burnt, and that if air was ex- cluded it underwent no change. No attempt, however, was made to afcertain the pro- dn£l, till Lavoificr undertook a feries of experiments tor that purpofe in 1772. He obtained rarionic acid gas. It might be concluded from thefe experiments, that the diamond contains carbon ; but it was referved for Mr Tennant to fhew that it confiited entirely of that fub- llance. Into a tube of gold, having one end clofed and a glafs tube adapted to the other to coUedl the produrt, that gentleman put 2{ grains of diamonds and a quar- ter of an ounce of nitre (m). This tube was heated flowly ; the confequence of which was, that great part of the nitric acid pafled off before the diamond took fire, and by that means almoll the whole of the carbonic 3cid formed during the combullion of the diamond re- mained in the potafs, for which it has a llrong affinity. To afcertain the quantity of this carbonic acid, he dii- folved the potafs in water, and added to the folution an- other fait compofed of muriatic acid and lime. Muria- tic acid has a ftronger affinity for potafs than for lime; it therefore combines with the potafs, and at the fame time the lime and carbonic acid unite and tall to the bottom of the veffcl, becaufe they are nearly infoluble in water. He decanted off the liquor, and put the lime which contained the carbonic acid gas into a glafs globe, having a tube annexed to it. This globe and tube he then filled with mercury, and inverted into a veffel con- taining the fame fluid. The lime by that means occu- pied the very top of the tube. It now remained to fepa- rate the carbonic acid from the lime, which may be done by mixing it with any acid, as almoft every other acid has a ftronger affinity for lime than carbonic acid has. Accordingly on introducing muriatic acid, 10,3 ounce meafures ot carbonic acid gas, or nearly 9,166 grains, were feparated. But, according to the experiments of Lavoifier, this gas is compofed of 72 parts of oxygen and 2H of carbon; 9,166 grains, therefore contain 2, 56 grains of carbon, which is almoll precifely the weight of the diamond confumed. It follows, therefore, that it was compofed of pure carbon*. The difficulty of burning the diamond is owing entirely to its hardnefs. Mefl'rs Morveau and Tennant rendered common charcoal fo liard by exj)ofn)g it for fome time to a violent fire in dole veiTels, that it loll much of its natural tendency to combuftion, and endured even a red heat without catch- ing fire f. Charcoal poffeffes a number of fingular properties, 219 which render it of confiderable importance. It is in-Hydr.>Kcn. capable of putrefying or rotting like wood, and is not'""'^ '"' therefore liable to decay through age. This property has been long known. It w3s cuftc-mary among the ancients to char the outfide of thofe flakes which were to be driven into the ground or placed in water, in or- der to preferve the wood from fpoiling. New-made charcoal, by being rolled up in cloths which have con- tracted a difagreeable odour, effedlually ilcltroys it. It takes away the bad taint from meat beginning to pu- trefy, by being boiled along with it. It is perliaps the bell teeth powder known. Mr Lowitz of Pelerfburgh has fhewn, that it may be ufed with advantage to puri- fy a great v.;riety of lubftances. Carbon unites with a number of bodies, and forms Carbmctj, with them compounds known by the name of carburets. Its affinities have not yet been afcertained. Sect. IV. Of Hydrogen. Put into a glafs veffel furnifhed with two mouths a - quantity of freih iron filings, quite free from rull. Lute\ierhod of into one of thefe mouths the end of a crooked glafsprocurTig tube. Infcrt the other end of this tube below a glafs *'y'^''<'g«"- jar filled with water, and inverted into a pneumatic ap- paratus. Then pour upon the iron filings a quantity of fulphuric acid, diluted with twice its own weight of water, and clofe up the mouth of the veffel. Imme- diately the iron filings and acid tffervcfce with violence, a valt quantity of gas is produced, which rufhes through the tube and fills the jar. This gas is called hydrogen gas {t^). It was obtained by Dr Mayow and by Dr Hales from various fubllances, and had been known long be- fore in mines under the name oit)neJi'e damp. MrCa- vendifh * was the fn (I who examined its properties with » pf.^ attention. They were afterwards more fully invelliga- iVan/rijje. ted by Prieftley, Scheele, and Fontana. Hydrogen, like a/r, is invifible and elaftic, and ca- its proper- pable of indefinite comprefTion and dilatation. ties. Its fpecific gravity differs according to its purity, Kirwan found it o,cooiof ; Lavoifier 0,000094 ;j:, or^OnPhlegif- about twelve times lighter than common air. *on , ft-et. 1 ft. All burning fubllances are immediately extin^uifhedL "''."'J'"'' ... 1,. 1. T-. ,.°. Uicmijlri, by benig plunged mio this gas. It is mcapable, there- ^fpinjfx, fore, of fupporting combuftion. Animals, when they are obliged to breathe it, die al- moft inftantaneoufly. Scheele, indeed, found that he could breathe it for lome time without inconvenience § ;^ Sdeilccn but Fontana, who repeated the experiment, difeoveredi"''"- that this was owing to the quantity of common air con- tained in the lungs when he began to breathe ; for 011 expiring as ftrongly as poflible before drawing in the hydrogen gas, he could only make three refpirations, and even thefe three produced extreme feeblcnefs and opprefhon about the breait p . II 7"""' '''• If a phial be filled with hydrogen gas, and a lighted ''^■'•'■''*'9'* candle be brought to its mouth, the gas will take fire, and burn gradually till it is all confumed. If hydro- E e 2 gen (m) Niti'e is compofed of potafs and nitric acid ; and nitric acid contains a great quantity of oxygen, w-hich is eafily feparated by heat. Diamond, when mixed with nitre, burns at a much lower heat than by any other procefs. j[n) It was formerly called irJlammaLle air,zin\ by fome ditrmVi^ phlogijloit. 220 C H E M I Hydrogen, rren and oxygen gas be mixed together and kindled, ' »r— ' lliey burn inllantaneoufly, and produce an ey.plollon like 'Tunpowder. The fame efFeft follows when a mix- ture of hydrogen gas and almofpherical air is kindled, but the exploiion is kfs viulent. Hydrogen gas will not biirii except in contatt with oxygen gas, nor will it burn even in contad with oxygen gas, unlcfs a red heat be applied to it. If 85 parts by weight of oxygen gas, and 1 5 of hydrogen gas, be mixed toge- ther, and fet on fire in a clofe veflll, they dil'appcar, and in their place there is found a quantity of water „ 3*„ exaAlv equal to them in weieht. This water miift be finn of wa- compufed of thele two gales ; tor it did not previoully tcr. exilt in the vcfTel, and no other fubftante except the gafcs was introduced. Water then is compofed ot oxy- gen and hydrogen ; and the combullion yt hydrogen is nothing elfe but the att of its combination with oxy- gen (o). It had been fuppofed, in confequence of the experi- ments of Dr Piicltley and feveral other philofophers, that when hydrogen gas was allowed to remain in con- tad with water, it was gradually dccompofcd, and con- _,. . verted into another gas; but Mr de Morveau *, Mr I X'n. J/**" Halfenfratz f , and Mr Libes^, have fliewn that it un- ti/OT.i. ipx.dergoes no change, provided fufBcient care be taken to f Jaur. J,' exclude every other gas. J'li;if ixxvi. Hydrogen gas difTolves fulphur, phofphorus, and car- bon. The compounds are calledyu^Ai»aW,/iAo/^io/-a- Compounds W, and carbonnled hydrogen gas. if hydro- j. Sulphurated hydrogen gas was firft examined with gen gas. attention by Scheele, \v\\o, together with Bergman, dif- covered many of its properties. Mr Kirwan likewife publifhed a very valuable paper on the fame fubjeiS. If equal parts of fulphur and potafs be melted together in a covered crucible, they combine together, and form a compound known by the name of fidphurct of potafs, but formerly called, from its red colour, hepar fulphur is, or li-uer of fulphur. When this fubltance is moiftened with water, it gives out a quantity of fulphurated hy- drogen gas; hence this gas was at firft called hepatic gas. Mr Gengenibre enclofed a bit of fulphur in a glafs velTel filled with hydrogen gas, and melted the fulphur by means of a burning-glals. A quantity of it difap- peared, and the hydrogen affunied all the properties of hepatic gas. Hence it follows that this gas is merely fulphur diffolved in hydrogen gas. The eafieft method of obtaining it Is to pour an acid, the muriatic for inftancc, on a quantity of the fulphuret reduced to powder. An effervefcence takes place, the gas is extricated, and may be coUefted by means of a pneumatic apparatus. The theory of this emiffion is obvious. The fulphur is gradually convert- ed into fulphuric acid, by decompofing the water, which is always united with acids, and feizing its oxygen : the hydrogen of the water is thus fet at liberty ; it af- fumes the gafeous form, and at the fame time difTolves S T R y. Part r. * F.ncycl. Mith'od. Sulphura- ted bydro- gcB gas. part of the remaining fulphur, for which it has a con-Hydroi-en, liderablc aflinity. ^ ' The fpeeltic gravity of fulphurated hydrogen gas is 0,00135*; it is to common air as 1 106 to 1000. * ^irwnn It has a very fetid odour, prccifely funilar to tWdt"" ^^'''•^'^"'* emitted by rotten eggs, which indeed is owing to the ^ ' emiffion of the very fame gas. It is not more rcfpirable than hydrogen gas. When fet on fire, in contaft with oxygen gas, it burns with a light blue flame, without exploding, and at the fame time a quantity of fulphur is depofited. The combuf- lion of this gas, then, is merely the union of its hydro- gei^, and perliaps part of its fulphur, with oxygen. This gas turns iyrup of violets to a green colourf.f Fourcrey't It does not feem capable of exiftinjr in atmufpherical '''"'""^'''-?'' •I . J ,- ■ f , ° ^ .'^ arl.Sulphur air without deeompolition ; tor the moment it comes into contaft with oxygen gas, fulphur is depofited :f. { Bergman. 2. Phofphorated liydrogen gas was difcovcred by Mr 4i Gergembre in 1783, and by Mr Kirwan fome time af- J'^"^'' j^"* ter, before he became acquainted with the experiments ^j, „j3_ of that gentleman. It may be procured by mixing phofphorus with potafs dilfolved in water, and applying a boiling heat to the folution. The phofphorus is gra- dually converted into an acid by decompofing the wa- ter, and uniting with its oxygen. The hydrogen af- fumes the form of a gas, and flies off after diflblving a little of the phofphorus. This gas may be coUefted by means of a pneumatic apparatus. Phofphorated hydrogen gas has a fmell refembling that of putrid filh. When mixed with oxygen gas or common air, it becomes luminous ; and on the applica- tion of the fmalleft heat, it burns with aftonifhing rapi- dity §. The produfts are water and phofphoric acid. 5 Kinean, The combuftion of this gas therefore is nothing elfe than the union of its phofphorus and hydrogen with oxygen, attended by an emiffion of heat and light. Phofphorated hydrogen gas may alfo be formed by introducing a bit of phofphorus into a jar containing hydrogen gas : but care mull be taken to make this gas as dry as poffible ; for its affinity with phofphorus is weakened in proportion to its moifture |]. II BrugimUl- 3. Carbonated hydrogen gas arifes fpontaneoufly inv!' ^'''"'' hot weather from marfiies, but always mixed with feve-'"/; °"'" ■ . «ii*, 1. 445' ral other gafes. Several fpecies of it have been lately difcuvered by the alTociated Dutch chemifts Bondt, DIeman, Van Troollwyck, and Lauwcrenberg^. WhenH Anr.de 75 parts of fulphuric acid and 25 of fpirit of wine are '^*'"'' ^^'* mixed together, a gas is extricated which fuffers no al-'^ teratioii from [landing over water. Its fpecific gravity 4» is 0,00111, or it is to common air as 9:9 to loco. Itj^"^"^^" has a fetid odour, and burns with a llrong compaftgas.. flame. When paffed through fulphur It is converted in- to fulphurated hydrogen gas, and at the fame time a quantity of carbon is depofited in the form of a fine powder ; It muft therefore be compofed of carbon and hydrogen gas. When burnt, the produft is carbonic acid (o) The hiflory of this great difcovery, and the obi.e£lions which have been made to it, we referve for the chapter which treats of Water, where they will be better underftood than they could be at prefent. ^This fub- flance was called hydrogen by the French chemills, becaufe it enters into the compofition of water, from ^i"? "wa- ter, and y""i^3i I am horn. Ohjeclions have been made to the propriety of the name, into which we fhall not enter. It ought never to be forgotten that Newton had long before, with a fagacity alraoll greater than human, corjedlured, from its great refratling power, that water contained a combuflibh fubflance. • IbiJ. f UiJ. 4.1 Part I. Hydrogen, acid gas and water*. By making ether (p) pafs thro' a red hot glafs tube, another carbonated hydrogen gas was formed, the Ipecffic gravity of which was 0,00086. Spirit of wine, pafTed in the fame manner, afforded a gas, the fpecific gravity of which was 0,1005.?, '^^'•^ which burned with a paler flame than the otlier two. Thcfe gafes were found to contain from 80 I0 74 parts of carbon, and from 20 to 26 of hydrogcii. The iiril fpecieo was found to contain moll carbon, and the lait to contain Icall f . The aflinity of hydrogen gas for thefc three combuf- Aflinitic'oftibles is as follows: tilde gafct. Sulphur, Carbon, Phofphorus (c^). Dr Auftin found, that by repeatedly pafling eleftric explofions through a fmall quantity of carbonated hy- drogen gas, it was permanently dilated to more than twice its original bulk. He rightly concluded, that this reiriarkable cxpanlion could only be owing to the ,..'*■ . . evolulion of hydrogen yas. On burniiU'" air thus ex- Attempt to , , , r ' , ? P • , *' • r dcompofe panded, he tonnd that it required a greater quantity or cdrbon oxygen than the f.ime quantity of gas not dilated by eleiitricity : An addition therefore had been made to the combullible matter ; for the quantity of oxygen neceflary to complete the conibuftion of any body, is always proportional to the quantity of that body. He concluded from thefe experiments, that he had decora- pofed the carbon which had been diffcilved in the hy- drogen gas; and that carbon was ccmpoled of hydro- gen and a7.ot(R), fome of which was always found in the veffel after the dilated gas had been burnt by means t PhU. of oxygen \. If this conclufion be fairly drawn, we Tru//. axx.mull expunge carbon from the lill of fimple fubilances, J'' and henceforth confider it as a compound. There was one. circumftance which ought to have prevented Dr Aullin from drawing this coiichilion, at leaft till warranted by mere deciiive experiments. The quantity of combuihble matter had been I'ncrealed. Now, if the expanlion of the carbonated hydrogen gas was owing merely to the decompolition of carbon, no fuch increafe ought tc have taken place, but rather the contrary; for the carbon, which was ittelf a combullible fubftance, was refolved into two ingredients, hydrogen and azot, only the lull of which burnt on the addition of oxygen and the application of heat. Dr Aullin's experiments have been lately repeated by Mr William c p,., Henry with a great deal of accuracy §. He found •/-,^„r'ij„.that the dilatation which Dr Auftin delcribes adlually part id. took place, but that it could not be carried beyond a certain degree, a little more than twice the original CHEMISTRY. 45 £x.iriiiiied, 221 bulk of the gas. Upon burnin|T feparately by means of Azot. oxygen, two equal portions of caibonsted hydrogen gas, * one of which had been expanded by elem- fent ftate of our knowledge, be confidered as a fimpleP°**^° fubftance. Dr Prieftley, who obtained azotic gas at a very early period of his experiments, confidered it as a compound of oxygen gas and phlogifton, and for that reafon gave it the name of phlogi/iicated air. Accord- ing to the theory of Stahl, which was then univerfally prevalent, he confidered combuftion as merely the le- paration of phlogifton from the burning body. To this theory he made the following addition : Phlogif- ton is feparated during combuftion by means of chemi- cal affinity : Air (that is, oxygen gas) has a ftrong af- finity for phlogifton : Its prefence is neceflary during combuftion, becaufe it combines with the phlogifton as it feparates from the combuftible ; and it even contri- butes by its affinity to produce that feparation : The moment the air has combined with as much phlogif- ton as it can receive, or, to ufe a chemical term, the moment it is faturaled with phlogifton, combuftion ne- ccffarily ftops, becaufe no more phlogifton can leave the combuf- (s) See his thefts De Aere Mephitico, pubhfhed in 1772. — " Sedaer falubris et purus refpiratione animali non modo ex parte fit mephiticus fed et aliam indoUs Jut mutalionem inde patitur. Poftquam enim omnis aer mephiti- rus (carbonic acid gas) ex eo, ope lixivii cauftici fecretus et abduflus fuerit, qui lamen rejlat nullo modo ialubrior jnde evadit ; nam quamvis nuUam ex aqua calcis prsecipitationem faciat baud minus quam antea et Jlammam et I'itam extingiiit. Page 17. " Aer qui per carbones ignitos folle adaftus fuit, atque deinde ab omni aere mephitico (carbonic acid gas) ex- purgatus, malignus tamen adhnc reperitur et omnino fimilis eft ei qui refpiratione inquinatur. Immo ab experi- meritis patet banc folam efte aeris mutationem quae inflammation! adfcribi poteft. Si enim accenditur materies quoilibet qua; ex phlogifto et bafi fixa atque fimplici conftat, aer inde natus ne minimam acris mephitici quantitatem in fe continere "videtur. Sic aer in quo fulphur aut phofphorus urinae cotnbuftus luit, licet maxime malignus, cal- cem tamen ex aqua minime praccipitat. Interdum quidem fi ex phofphoro natus tuerit, nubeculain aquae calcis inducit fed tenuiffimam, nee acri mephitico attribuendam, fed potius acido illi quod in phofphoro ineft, et quod, ut experimenta docuerunt, hoc fingulari dote pollet." Page 19. (t) Hence the name azot, given it by the French chemifts, which fignifies dejlrudive to life, from « and f^i". (u) It is remarkable enough, that the acidity of nitric acid was afcribed by Mayow, in 1674., to the pretence of oxygen. Indoles caujlica 'piritus nilri (fays hej a particulis ejus igneo-aereis j^rovenil. Traft. p. 19- Part I. C H E M Aznt. combuftible (v) : Air faturated with phlogifton is azo- ""~v~~- tic gas. This was a very ingenious theory, and, when Dr Prieftley pubh'fhed it, exceedingly plaufible. A great number of the moft eminent chemifts accordingly embraced it : But it was foon after difcovered, that during combullion the quantity of air, inftead of in- creaiing, as it ought to have done, had phlogifton been added to it, aftually diminilhed both in volume and - weight. There was no proof, therefore, that during combuftion any fubftance whatever combined with air, but rather the contrary. It was difcovered alfo, that a quantity of air combined with the burning fubftance during combuftion, as we have feen was the cafe with fulphur, phofphorus, carbon, and hydrogen ; and that this air had the properties of oxygen gas. Thefe dif- coveries entirely overthrew the evidence on which Dr Prieftley's theory was founded ; accordingly, as no at- tempt to decompound azot has fucceedtd, it has beei» given up by almoil every chemift excejit Dr Prieftley himfelf. Atmofpheric air, as Schtele firil proved, is oom- pofed of about 27 parts of oxygen and 73 of azotic gas. During combuftion, the oxygen is abftrafted and the azotic gas remains behind. La Metherie made an attempt to prove that azot was compofed of oxygen and carbon (w). He took a bit of burning charcoal, extiuguilhed it in mercury, and then plunged it while hot into oxygen gas. On being plunged into water, one fourth of the gas was dilenga- ged, and part of it was found to confift of azotic gas. From this he concluded that he had formed azotic gas by combining oxygen and carbon : But it was proved by Mr Lavoifier, beyond the poffibility of doubt, that oxygen and carbon form carbonic acid gas. They can- not then certainly form azot ; for two contradiftory lafts cannot both be true. There mull then have been fomething overlooked in the experiment. Indeed the experiment itfelf does not warrant the conclufion which De La Metherie drew from it. He did not afcertain whether the weight of the charcoal was diminiftied ; and, befides, there was azot mixed with the oxygen gas "ivhich he employed, as he himielf has informed us : And how was it pcffible for him to admit the charcoal into water without, at the fame time, admitting fome atmofpherical air ? We have now defcribed all the combuftibles which are at prefent reckoned fimple, except the nietals. We have found, that during combuftion all of them com- bine with oxygen ; that no part of them is difengaged, no part of them loft : we have therefore concluded, that the combuftion of thefe fuhftances is nothing clfe but the aft of their uniting with oxygen. We have feen, however, that none of them, except phofphorus, was capable of uniting with oxygen at the common temperature of the atmofphere ; that, iu order to pro- duce the union, heat was necelfary, and that the degree of this beat v/as different for each. Hydrogen required a red heat, and azot a ftiU greater. We have feen. I S T R Y. 225 too, that during tliefe combinations a quantity of heat Metals, and light efcaped. Now, why is heat necefTary for thefe '— v— ~' combinations ? and whence come the heat and the light which we perceive during the combuftion of thefe bo- dies ? Thefe queftions are of the highell importance, and can only be anfwered by a particular invtftigation of the nature and properties of lieat and light. This inveftigation we (hall attempt, as foon as we have de- fcribed the mttals and cirths, which form the fubjeft of the two following chapters. CiiAP.lII. 0/ Metals. J4 Metals may be confidered as the great inftruments Properties of all our improvements : Without them, many of the°^ metals, arts and fciences could hardly have exifted. So fen- lible were the ancients of their great importance, that they raifed thofc pcrfyns who firft difcovered the art of working them to the rank of deities, fn chemiftry, they have always filled a conlpicuous ftation : at one period the whole fcience was confined to them ; and it may be faid to have owed its very exiftence to 3 raj^c for making and tranfmuting metals. 1. One of the moft confpicuous properties of the Liiltre. metals is a particular brilliancy which they poffefs, and which has been called the metallic lujtre. This proceeds from their reflefti?ig much more light than any other body ; a property which fecins to depend partly on the clofenefs of their texture. This renders them peculiar- ly proper for mirrors, of which they always form the balls. 2. They are abfolutely opaque, or impervious to Opatit" light, even after they have been reduced to very thin plates. Silver leaf, for inft^nce, tttb^ss- of an inch thick, does not permit the fmallell ray of hVht to pafs throught it. Gold, however, may be rendered tranf- parent ; for gold leaf, t-jb-'ob^ of an inch thick, tranf- mits light of a lively green colour*. And it is not » KhhoJ improbable that all the other metals, as Sir Ifaac Newton fo,}, "noi,^ fuppofcd, would become tranfparent, if they could be «" f'ourcro^ reduced to a fufficient degree of thinnefs. It is to tiiis opacity that a part of the excellence of the metals, as mirrors, is owing ; their brilliancy alone would not qua- lify them for that purpofe. 3. They may be melted by the application of heat, PufiSility, and even then ftill retain their opacity. This property enables us to cail them in moulds, and then to give them any fliape we pleafe. In this manner many elegant iron utenfils are formed. 4. Their fpecific gravity is greater than that of any Gravitf. other body hitherto difcovered. ?. They are better condudlors of eledricity than any other body. 6. But one of their moft important properties is Malleabili, malleabiltty ; by which is meant the capacity of being 'X- extended and flattened when ftruck with a hammer. This property enables us to give the metallic body any form we think proper, and thus renders it eafy for us to (v) This ingenious theory was firft; conceived by Dr Rutherford, as appears from the following palTage of his thefis. " Ex iifdem etiam deducere licet quod aer ille malignus (azotic gas) componitur ex aere atmofbhericrt , cum phlogiflo u/iito et quafifatiirato. Atque idem confirmatur eo, quod aer qui meiallorum calciiiationi jam in-.- ferviit, et phlogifton ab iis abripuit, ejufJem plane fit indolis." De aere Mephitico, p. 20. (w) Or rather of hydrogen, for he confidered carbon itfelf as a compound. CHEMISTRY. Part I. to convert tliem into tlie various inftruments for which Were the calcination to be continued long enough to Mcud^. we liave occalioii. All uu-tals do not poiL-fs tliis pro- deprive them altogether of phlogilton, they would be -^"v— ^ ^ perty ; but it is remarkable that almoil ;ill thofe which reduced to the (late of other earths; and then it would ■ 60 es of metals were known to the ancients have it. Heat increaieti be etpially difficult to convert them into metals, or, to this property confiderably. ^^^ a chemical term, to reduce them. Accordingly wt; **. Another property which 13 alfo wanting in many find that the more completely a calx has been calcined, of the metals, \% duallily ; by which we mean the capa- the more dilficult is its redudlion. This explanation city of being drawn out into wire by being forced was favourably received. But after the charaCU'rillic Portlier im« throuoli iioles of various diameters. This property has properties of the various earths had been afcertained.P''''*^'*" by fjnie bee.i called lenacily ; and it doubtlel's depends and the calces of metals were accurately examined, it upon the tenacity of the v.iiiuus metals. was perceived that the calces differed in many particu- f- 1 ^'. • 8. When expofed to the action of heat and air, mod lars from all the earths, and from one another. To call of the metals lofe their lullre, and are converted into them all the fame fubltance, tlien, was to go much far- earthv-like powders of diiferent colours and properties, ther than either experiment or obfervation would war- according to the metal and the degree of heat emplo) cd. rant, or, rather, it was to declare open war agaiiill both Several of the metals even take fire when expofed to experiment and obfervation. It was concluded, there- a ftron-T enough heat^; and after combuilion the refi- fore, that each of the metals was compoled of a pecu- du'.im is found to ,je the very fame earthy-hke fub- liar earthy fub/lance combined with phlogifton. For ftance. If any of thefe calces, as they are called, be this great improvement in accuracy, chemillry is chiefly mixed " ith charcoal-powder, and expofed to a ftrong indebted to Bergman. 65 hea in a prope- vefTel, it is changed again to the metal But there were feveral phenomena of calcination Still impi Stahl's the- from which it was produced. Froin thefe phenomena which had all this time been unaccountably overlooked, 'ed. oryofthe Slahl concluded, that metals v/ere compoled of earth The calces are all confiderably heavier than the metals compol'ition^j^jj y,/^/g ^(/(^_ He was of opinion that there was only from which they are obtained. Boyle had obferved "'^ """"'" Qj,g primitive earth, which not only formed the bafis of this circumllance, and had afcribed it to a quantity of all thofe fnbftanccs known by the name of earths, but fre which, according to him, became fixed in the me- the balls rlfo of '--'^c wci^i- nhlo^-illon ; and concluded, therefore, with Beccher, that" voifier publiflicd his celebrated experiments on caleina-^ ' there' was another princtple befides earth and phlogif- tion, in the Memoirs of the Paris Academy for 1774. ton wiiich entered into the compofition of the metals. He put eight ounces of iin into a large glafs retort, the To this princi')le Beccher gave the name of mercur':a! point of which was drawn out into a very (lender tube earth, becaufe, accoiding to him, it exilled moll abun- to admit of eafy fulion. This retort was heated flowly dantly in mercury. This principle was fuppofed to be till the tin began to melt, and then fealed hermetically, very volatile, and therefore to fly off during calcination: This heat was applied to expel fome of the air from and fome chemifts even aflirmed that it might be ob- the retort : without which precaution it would have ex- tained in the foot of thofe chimneys under which metals panded and burft the veffel. The retort, which was have been calcined. capable of containing 250 cubic inches, was then weigh- A ftriking defeft was foon perceived in this theory, ed accurately, and placed again upon the fire. The tin 67 The orijrinal metal may again be produced by heating foon melted, and a pellicle formed on its top, which Uefuied by its calx along vvitlpfome other fubftance which contains was gradually converted into a grey powder, that funk '-^''■"''"^'■• phlofrifton : now, if the mercurial earth flies off during by a little agitation to the bottom of the liquid metal : combuftion, it cannot be neceffary for the formation of in fliort, the tin was partly converted into a calx. This complete metals, for they may be produced without it : procefs went on for three hours ; after which the cal- if on the contrary, it adheres always to the calx, there cination flopped, and no farther change could be pro- is no proof of its exiftence at all. Chemills, in confe- duced on the metal. The retort was then taken from Quence of thefe obfervations, found themfelves obliged the fire, and found to be precifely of the fame weight to difcard the mercurial principle altogether, and to as before the operation. It is evident, then, that no conclude that metals were compoled of earth only, new fubftance had been introduced, and that therefore united to phlogifton. But if this be really the cafe, the increafed weight of calces cannot, as Boyle fuppo- how comes it that thefe two fubftances cannot be uni- fed, be owing to the fixation of fire (x). ted bv art ? Henkel was the firft who attempted to «3 Defeilive. ■ *4 folve this difficulty. According to him, earth and Improved ' ~ ' When the point of the retort was broken, the air rufhed in with a hiffing noife, and the weight of the improved j^j^.^jfl-on are fubflances of fo oppofite a nature, that retort was increafed l>y ten grains. Ten grains of ^" ^ "ft is exceedingly difficult, or rather it has been hitherto air, therefore, mull have entered, and, conlequenlly, impoffible, for us to commence their union ; but after precifely that quantity mull have difappeared during it has been once begun by nature, it is an eafy matter the calcination. The metal and its calx being weigh- to complete it. No calcination has hitherto deprived ed, were found juft ten grains heavier than before : the metals of all their phlogifton ; fome Hill adheres to therefore, the air which difappeared was abforbed by the calces. It is this remainder of phlogifton which the metal : and as that part of the tin which remained renders it fo eafy to reftore them to their metallic ftate. in a metallic ftate was unchanged, it is evident that this air (f\ This experiment had been performed by Boyle with the fame fuccefs. He had drawn a wrong conclufion from not attending to the ftate of the air of the veflel. Shatu' s Boyle, II. 394. Part I. C H E M Metals, air muft have united with the calx. The increafe of ^ /""■ weight, then, whicli metals experience during calcina- tion, is owing to their uniting with air (y). But all the air in the veflel was not abforbed, and yet the cal- cination would not go on. It is not the whole, then, but feme particular part of the air which unites with the calces of metals. By the fubfequent difcoven'es of Prieftley, Scheele, and Lavoifier himfelf, it was afcer- tained, that the reflduum of the air, after calcination has been performed in it, is always pure azotic gas : It follows, therefore, that it is only the oxygen which com- bines with calces; and that a metallic calx is not a fimple fubftance, but a compound. Mr Lavoifier obferved, that the weight of the calx was always equal to that of the metal employed, together with that of the oxy- gen abforbed. It became a queftion then, Whether metals, during calcination, loft any fubftance, and con- fequently, whether they contained any phlogifton i' Mr Lavoifier accordingly propofed this queftion ; and he anfwered it himfelf by a number of accurate experi- ments and ingenious obfervations. Metals cannot be cal- cined excepting in contaft with oxygen, and in propor- tion as they combine with it. Confequently they not only abforb oxygen during their calcination, but that abforp- tioo is abfolutely neceflary to their affuming the form of a calx. If the calx of mercury be heated in a re- tort, to which a pneumatic apparatus is attached, to the temperature of i 200°, it is converted into pure mer- tcury ; and, at the fame time, a quantity of oxygen fe- parates from it in a gafeous form. As this procefs was performed in a clofe veffel, no new fubftance could en- ter : The calx of mercury, then, was reduced to a me- tallic ftate without phlogifton. The weights of the metal and the oxygen gas are together juft equal to that of the calx ; the calx of mercury, therefore, muft be compofed of mercury and oxygen ; confequently there is no reafon whatever to fuppofe that mercury contains phlogifton. Its calcination is merely the adi of uniting it with oxygen (z). The calces of lead, filver, and gold, may be decompof^d exaftly in the fame manner ; and Mr Van Marum, by means of his great eleftrical machine, decompofed alfo thofe of tin, zinc, and antimony, and refolved them into their refpeftive • Jour.Ji metals and oxygen *. The fame conclufions, therefore, thy/. ijSs- muft be drawn with refpeA to thefe metals. All the metallic calces may be decompofed by prefenting to Suppt.VoL. I. Parti. I S T R Y. 225 then^ fubftances which have a greater affinity for oxy- Mttali. gen than they have. 1 his is th • -earoii that ciiarcoal- '""V— ' powder is fo efficacious in reducing them : and if they are mixed with it, and heated in a proper vcnc), fur- niftied with a pneumatic apparatus, it will be cafy to difcover what pafles. During the redudion, a great deal of carbonic acid gas comes over, which, together with the metal, is equal to the weight of the calx and the charcoal : it muft therefore contain all the ingre- dients; and we know that carbonic acid gas is compo- fed of carbon and oxygen. During the procefs, then, the oxygen of the calx combined with charcoal and the metal remained behind. It cannot be doubted, therefore, that all the metallic calces are compofed of the entire metals combined with oxygen ; and that cal- cination, like combuftion, is merely the aft of this com. bination. All metals, then, in the prefent ftate of che- miftry, muft be confidered as fimple fubftances ; for they have never yet been decompounded. ,„ The words calx and calcination are evidently impro- Oxide and per, as they convey falfe ideas; we ftiall therefore af- oxidation, terwards employ, inftead of them, the words oxiJe and*''^'- oxidation, which were invented by the French chemifts. A metallic oxide fignifies a metal united with oxygen ; and oxidation implies the a&. of that union. Metals are capable of uniting with oxygen in diffe- rent proportions, and, confequently, of forming each of them different oxides. Thefe are diftinguifhed from one another by their colour. One of the oxides of iron, for inftance, is of a green colour ; it is therefore called the green oxide ; the other, which is brown, is called the brotvn oxide. r The metals at prefent amount to 21 ; only 11 of Number of which were known before the year 1730. Their names metals, are gold, filver, platinum, mercury, copper, iron, tin, lead, zinc, antimony, bifmuth, arfenic, cobalt, nickel, manganefe, tungften, molybdenum, uranium, telluiium, titanium, ciii'omum. The firft eight of thefe were formerly called metah by way of eminence, becaufe they are pofleffed either of malleability or duftility, or of both properties toge- ther ; the reft were called y^«;W/j/.', becaufe they are brittle. But this diftlnftion is now pretty generally laid afide ; and, as Bergman obferves, it ought to be fo altogether, as it is founded on a falfe hypothefis, and conveys very erroneous ideas to the mind. The firft F f four the (y) It ik remarkable that John Rey, a phyfician of Perigord, had afcribed it to this very caufe as fa^ back as : year 1630 : But his writings had excited little attention, and had funk into oblivion, till after his opinion bad been inconteftibly proved by Lavoifier. Mayow alfo, in the year 1674, afcribed the increafe of weight to the combination of metals with oxygen ^lippe I'ix concipi potejl (lays he), unde augmentum iHud antimonii (calcinaH) nifi a partiadis nitro-aereis igneifque inter calcinandum nxis procedat. Trad. p. 28. Plane lit an;im"nii fixatio non tarn a fulphuris ejus externi ajjhinptione, quam particuHs nitro-aereis, quilus jlamma nitri abundat Ei ;t:FixJS prove- fiire "videatur. Ibid. p. 29. _(z) This experiment was performed by Mr Bayen In 1774. This philofopher perceived, earlier than La. voifier, that all metals did not contain phlogifton. " Ces experiences (fays he) vont nous detrompcr. Je ne tiendrai plus le langage des dlfcljjles de Stahl, qui feront forces de rcftreindre la dodrlne fur le phlogiftlqne, ou d'avouer que les precipites mercurials, dont je parle, ne font pas des chaux metalliques, ou enfin qu'il y a des chaux qui peuvent fe reduire fans le concours du phlogiftique. Les experienceii que j'ai faitcs me force' de conclure que dans la chaux mercuriale dont je parle, le mercure doit fon etat calcoire, non a la perte du plylogi/liqite qu'il n'a pas efiiiyee, rnais a fa comhinaifon intinie avec le fuide ehfique, dont le poids ajoute a celui du mer- cure eft la feconde caufe de I'augmentalion de pefanteur qu'on obferve dann les precipites que j'ai foumis a I'examen." Jour, de Phyf. 1774, pages 288, 295. It was in confequence of hearing Baycn's paper read that Lavoifier was induced to turn his attention to the fubjed. 226 GclJ. TO Propt rties of guld. four metals were formerly called iwhk or perfccl melals, becaiifi; their oxides are reducible by the mere appli- cation of heat ; the next four were imptrficl metals, be- caufe their oxides were thought not reducible without the addition of fome combulHble fubilance ; but this diftinction alfo is now very propeily CNploded. Sect. I. Of Gold. Gold fcems to have been known from the very l)e- glnning of the world. Its properties and its fcarcity have rendered it more valuable tiuin any other metal. It is of K'trvians for fome hours to the utmoft heat of Mr Parker's lens f . JMinfr.i.yj.Mr Lavoifier, however, obferved, that a piece of filver, held over gold melted by a fire blown by oxygen gas, which produces a much greater heat than common air, was fennbly ^;.V : Part of the metal, then, mull have been volatilized. After fufion, it is capable of afTiiming a cryftalline form. Tillet and Mongez obtained it in iliort qua- drangular pyramidal cryftals. It is capable of combining with oxygen, and form- ing an oiade of gold. There are two methods of produ- cing this combination, the application of heat, 2.xiii Jolu- tion in acids. When it is expofed to a very violent heat CHEMISTRY. ill contaft with air, gold abiorlis oxygon. Oxidation ef goUJ. Part I But the ^'^■'i- temperature mu(l be very high ; fo high, iiukcj, that ^~-~Y~"~ hardly any certain method of oxidating gold by heat is known, except by cletlricity. When the eleftric ex. plolion is tranfniitted through gold leaf placed between two plates of glafs, or when a ftrong charge is made to fall on a gilded lurface — in both cafes the metal is oxi- dated, and afuiincs a purple colour. It has been faid alfo, that the fame efleft has been produced by a very violent five 4 but few ot the iiillances wljieh have been adduced are well authenticated. The other method of oxidating gold is much eafier. For this purpole, equal parts ot nitric and muriatic acids arc mixed together" (c) and poured upon gold; an effervefcence takes place, the gold is gradually dif- folved, and the liquid alFumes a yellow colour. It i:- eafy to fee in what manner this folution is produced. No metal is foluble in acids till it has been reduced to the Rate of an oxide. There is a ftrong alHiiity be- tween the oxide of gold and muriatic acid. The ni- tric acid furnilhes oxygen to the gold, and the muria- tic acid diflfolves the oxide as it forms. When nitric acid is deprived of the greater part of its oxygen, it af« fumes a gafeous form, and is then called nitrous gas. It is the emiffion of this gas which caufes the effervef- cence. The oxide of gold may be precipitated from the nitro-muriatic acid by pouring in a little potafs dilfolved in water, or, which is much better, a little lime ; both of which have a ftronger afSnity for muriatic acid than the oxide has. This oxide is of a yellow colour. It is probable that gold is capable of two different degrees of oxidation, and of forming two difTeient oxides, theyelloiu and the purple : But neither the quan- tity of oxygen contained in thefe oxides, nor the dif- ferences between them, have been accurately afcertairtd. The oxides of gold may be decompofed in clofe veiTels by the applicalion of heat. The gold remains fixed, and the oxygen aflumes the gafeous form. They may be decompofed, too, by all the fubftances which have a ftronger affinity with oxygen than gold has The af- finities of the oxides of gold, according to Bergman *,* Bergman are as follows : Muriatic acid, Nitro-muriatic, Nitric, \ Sulphuric, Arfeiiic, Fluoric, • Tartarous, n EteBivt AttraSialts, Qpufc. 1,3. (a) We have borrowed from Mr Kirwan the method of denoting the different degrees of hardnefs by figures, which we think a great improvement. Thefe figures will be undcritood by Mr Kirwan's own explanation, which we here fubjoin. 3, Denotes the hardnefs of chalk, 4, A fuperior hardnefs, but yet what yields to the naih 5, What will not yield-to the nail, but eafily, and without grittinefs, to the knife. 6, That which yields more difficuk'y to the knife. 7, That which fcarcely yields to the knife. 8, That which cannot be fcraped by ;i knife, but does not give fire with fteel. 9, That which gives a lev.' feeble fparks with fteel. 10, That which gives pkntiful lively fparks. Kirniian^s Mineralogy, I. 38. (b) According to the caJculation of the Dijon academicians, it melts at 1 2980 Fahr. ; according to Bei:g- man, at 1301°. fc) This mixture, from its property of diffolving gold, was formerly called aqua regta (for gold, among the alchymifts, was the king of metals) ; it is now called nitro-muriatic acid. Phofpliure of gold. * Ann. de dim, i. 71. \ lUJ.XVU. 104. Part I. C H E M Silver. Tartarouaj *" ' • Phofphonc, Sebacic, Pruffic, Fixed alkali (d), Ammonia. « Gold is not changed either by air or water. It does not feem capable of combining either with fulphur or carbon. Mr Pclteticr combined it with phoiphorus, by melting together in a crucible half an ounce of gold «^ and an ounce of phofphoric glafs (e), iurrounded with charcoal. The phofphiirtt of gold thus produced was brittle, whiter tlian gold, and had a cryllaUized appear- ance. It was compofed of 23 parts of gold and one of phofphorus *. He formed the lame compound by dropping fmall pieces of phofphorus into gold in fu- ll on \. Gold is iilfo capable of combining with mod of the metals. Its affinities are placed, by Bergman, in the fuUowing order : Mercury, Copper, Silver, Lead, Bifmuth, Tin, Antimony, Iron, Platinum, Zinc, Nickel, Arfenic, Cobalt, Manganefc, Phofphorus ? Sulpliurets of alkalies. Sect. II. Of SUvrr. Silver appears to have been known almoft as early as gold. It is a metal of a Ihining white colour, with- out either tafte or fmell. It is the moft malleable and duftile of all metals ex- cept gold, and perhaps platinum. It can be reduced to leaves about rs-a^ij^ of an inch thick, and drawn into wire much finer than a human hair. Its tenacity is fnch, that a wire of filver, tV^ °f 3" inch in diameter, is capable of fuilaining 270 pounds ', without breaking }:. Its hardnefs is 6,^ §. Its fpecific gravity, before hammering, is 10,474; after hammering, io,5io|| : for it is remarkable that the fpecific gravity of almoft all the metals is increafed by hammering. It continues melted at 28" Wedgewood (f), but re- f A'iVTOan*j Sebacic, Oxalic, Sulphuric, Saccholadtic, Phofphoric, Sulphurous, Nitric, Arfenic, Fluoric, Tartaric, Citric, Formic, Laftic, Acetous, Succinic, rrufllc. Carbonic, Ammonia. When filver is melted with fulphur in a low red heat, .Sulphuret it combines with it and forms fulphuret of Jilver. It is of filver. very difficult to determine the proportion of the ingre- dients which enter into the compofition of this fub- ftance, becaufe there is an affinity between filver and its fulphuret, which difpofes them to combine together. The greateft quantity of fulphur which a given quan- tity of filver is capable of taking up is, according to Wenzel, tVo t- Sulphuret of filver is of a black ox\I^''i-A^' very dc^ep violet colour, brittle, and much more fufible than filver. If fufficient heat be applied, the fulphur is volatilized, and the metal remains behind in a ftate of purity. If one ounce of filver, one ounce of phofphoric glafs, Ph,,fphuret and two drams of charcoal, be mixed together, and of filver. heated in a crucible, phofphuret of filver is formed. It F f z is (d) Have the alkalies any affinity for the yellow oxide ? Is not their affinity confined to (he purple oxide alone ? And does not this oxide adl as an acid ? (e) Phofphoric acid evaporated to drynefs, and then fufed. (f) According to the Dijon academicians, it melts at 1044° Fahr. ; according to Bergman, at iooo'-\ (g) Metallic oxides, after fufion, are called ^/a/>, becaufe they acquire a good deal of refemblance, in fome particulars, to common glafs. * PMttier, Ann de Ch'tm. i. 73- \ liiJ. 3d;i. 1 10. 77 Alloys of iilver. i Tranjla- i:on cf Wac querns Ty'i£i. art. Alhy. Becf^'mes tarniflied by ex^o- furc. C H E M I is of a white colour, anti appears granulated, or as it were cryftalllzed. It breaks undtr the hammer, but may be cut with a knife. It is compofed of four parts of filver and one of phofph )rus. Heat decompofes it by feparating the phofphorus *. Pelletier has obferved, that iilver in fufion is capable of combining with more phofphorus than folid filver : for when phofphuret of iilver is formed by projefting phofphorus into melted filver, after the crucible is taken from the fire a quan- tity of phofphorus is emitted the moment the metal con- geals f. Silver does not feem capable of combining with car- bon. Silver is capable of combining with gold, and form- ing an aUoy ( h ) compofed of one part of fdver and five of gold. That this is the proportion of the ingredients, was difcovercd by Romberg. He kept equal parts of gold and filver in gentle fufion for a quarter of an hour, and found, on breaking the crucible, two malTes ; the uppermoft of which was pure filver, the undermoll the whole gold combined with ^th of filver. Silver, however, may be mixed with gold in almofl any proportion. But there is a great difference between the mixture of two fubftances and their chemical combination. Metals which melt nearly at the fame temperature may be mixed from that very circumftance in any proportion ; but fubftances can combine chemically only in one pro- portion. This obfervation, which is certainly of im- portance, was firfl made, as far as we know, by Mr Keir J. The alloy of filver and gold is of a greenifh colour ; but its properties have not yet been accurately examined. Silver is not effefted by water, nor by expofure to the air ; but Mr Prouft has remarked, that when long expofed in places frequented by men, as in churches, theatres, &c. it acquires a covering of a violet colour, which deprives it of its luftre and malleability. This covering, which forms a thin layer, can only be detach- ed from the filver by bending it, or breaking it in pieces with a hammer It was examined by Mr Prouft, and found to be Julplmret of filver. He accounts for this tranfition of the filver into a fulphuret, by fuppofing S T R Y. that a quantity of fulphur is con ftantly formed and ex- haled by living bodies *, The affinities of filver, according to Bergman, are as follows : Lead, Copper, Mercury, Bifmuth, Tin, Gold, Antimony, Iron, Manganefe, Zinc, Arfenic, Nickel, Platinum, Sulphurets of alkalies. Sulphur, Phofphorus. Sect. III. Of Platinum. The metals hitherto defcribed have been known to mankind from the earlieft ages, and have been always in high eftimation on account of their beauty, fcarcity, duftility, and indeftruftibility. But platinum, though perhaps inferior to them in none of thefe qualities, and certainly far fuperior in others, was unknown, as a dif- tinM ait, If I An:!, de Ciii/n. xxiv, t UiJ. 9+ Afliniiie!. The eaficfi; way of fonning this amalgam is to throw fmall piccts of red hot gold into mercury. The pro- portions of the ingredients are not eafily determined, bteaiife the amalgam has an afiinity both fur the gold and the meicury ; in conlequcnce of which they appear to combine in any proportion. Molt probably it is compufed of two piirts of gold and one of meicury. The coivibination is formed mod readily in thefe pro- portioiib ; and if too much mercury be addeil, it may be feparated by filtration. Tlie amalgam is of a white colour, and of the conlillence ol butter*. This amal- gam cryftullizes in quadrangular prifms ; whicli cry- rtals, accoiding to the Dijon academicians, are conipo- fed of fiK jjaits of mercury and one of gold. It is much uM ill gilding. 2. The amalgam of filver is lande in the fame man- ner. It forms dendritical cryllal.-;, which, according to the Dijon academicians, contain eight parts of mercury and one of filver. Gcilert was the fn It who remarked that its fpecitic gravity was greater than that ol ratr- cury, though that of lilver be lefs. 3. Dr Lewis attempted to form an amalgam of pla- tinum, but hardly fucceeded after a labour which lafled for feveral weeks. Mr Morveau fucceeded by means of heatf. But a much more expeditious method has been lately difcovered by Count Mouflin Poufchin. He took a dram of the orange-coloured lidt, compofed of ox'ulc of platinum and ammonia (o), and triturated it with an equal weight of nitrcury in a mortar of chal- cedony. Ii. a few minutes the fait became brown, and afterwards acquired a greenilh lliade. The matter was reduced to a very fine powder. Another dram of mer- cury was added, and the trituration continued : The matter became grey. A third dram of mercury began to form an amalgam ; and fix drains made the amalgam perfeft. The whole operation fcarce laftcd 20 minutes-. Mercury was added till it amounted to nine times the weight of the fait, and yet the amalgam continued very tenacious. It was eafily fpread out under the pellle ; it received the impreffion of the moll delicate feals, and had a very clofe and brilliant grain. This amalgam is decompoied, and the mercury' pafTcs to the Hate of black oxide iiy the fimple contaCl of feveral of the me- tals and a great number of animal matters. This cffetl even takes place on rubbing it between the fingers \. The affinities of mercury, as afcertained by the expe- riments of Morveau (p), are as follows : Gold, ' Silver, Tin, Lead, Bifmuth, Zinc, Copper, Antimony, Arfenic (0> Iron. Sect. V. Of Coppir. Except gold and fdver, copper feems to have been more early known than any other metal. In the firft Copper. ages of the world, before the metlujd of working iron ' was difcovered, co]iper was a principal ingredient in all dome'lic utcnlils and iiiih-uments of war. Lven during the Trojan war, as we learn from Homer, the comba- tants had no other armour but what was made of bronze, which is a mixture of copper and tin. The word copper is derived from the illaiid of Cyprus, where it was tirft difcovered, or at leaft wrought to any ex- tent, by the Greeks. 55 Copper is of a pale red colour with a fliade of yel- Propertiei low. Its talle is ilyptic and naufeous ; and when vub-of 'oppsr- bed it emits a difagreeable fniell. It poflefi'ts a confi- dtrable degree of malleability, though lefs than filver. Its tenacity is fuch, that a wire of -,'j, "f an inch in dia- meter can fuilain a weight of 299J poujids without breaking*. _ *Maiijuir't Its hardnefs is 8f. Its fpecific gravity, when not Dia. hammered, is 7,788 ; when wire-drawn, 8,878$. The t^^^^^ff '' fpecific gravity of Japan copper is 9,000 J ; that oi^J^"' "* Swediili coppt», 9,3243 ||. _ } Brijfon. It melts at 27" Wedgcwood ; according to the cal-§ Ktirs cuhtion of the Dijon academicians, at 1.^49" Fahrenheit. ^"' "", When allowed to cool flowly, it affumes a cryftalllne ^^J""' form. The Abbe Monge, to whom we owe many || Bergman, valuable experiments on the cryilallization of metals, ii. 263. informs us, that thefe cryftals are quadrangular pyra- mids, frequently inferted into one another. jj When copper is heated red hot in contaft with air, Brown it is foon covered with a brown earthy crufl, which mayo^"''^ °f be ealily feparated by hammering or by plunging the me-'"^^^'^'' tal into water. If the heat be continued, another fcale of the fame kind foon forms ; and by continuing the pruccfs the whole metal may be converted into an ear- thylike cnill, which ;s merely a combination of copper and oxygen, and is therefore called broiun oxide of copper. Ir is compofed of about 84 paits of copper and 16 of oxygen*. *■ Kirwan', When copper is diffolved in fulphurlc acid, and pre- 0.' ' cipitated by means cf lime, it falls in the form of a blue- <)y coloured powder, which is the blue oxide of copl/cr. If Blue and this oxide of copper be dried in the open air, it anumesK''^'j'' a green colour, and is then called \.\\e green oxide of cop' per. I'his laft oxide may alfo be produced by diililling a fufficient quantity of nitric acid off copper. Little fatlsfadtory is yet known with refpedt to thefe oxides ; it has not even been afcertained whether the blue and green be really two difFtrent oxides, or whether the dif- ference in colour be owing to fome other caulc. It is probable, however, that the _j«m oxide contains more oxygen than the blue ; becaufe the blue oxide affumes a green colour when expofed for fome time to the open air, during which it may be fuppofed to abforb oxygen. An experiment of Fourcroy proves inconteftibly, that the brown oxide contains lefs oxygen than the green. He converted the green oxide into the brown by applying heat; and during tire diftillation obtained oxygen gasf .f Fo»k«j( Tlie affinities of the oxides of copper, according to'"" '°'- Bergman, are as follows : ' y^^^ 3(5. Pyro- mucous acid I rities. Oxalic, \Scbrkksl. Tartarous, (o) .Ammonia Is an alkali hereafter to be defcribed. It is often called, in Englilh, harljhorn, (p) We (hall have occafion to confider thefe celebrated experiments afterwards. (ci,) Thefe two are added from Bergman. Bergman places had before tin, and zinc before bifmuth. 99 Siilphiiret of copper. C H E M I Tartarous, Muriatic, Sulphuric, SaccholuAic, Nitric, Sc'acic, Arfciiic, Phofphoric, Succinic, Fluoric, Citric, Formic, X.aAic, Acetous, Boracic, Pruffic, Carbonic, Fixed alkalies. Ammonia, Fixed oils. Wh-n copper is long expofed to the air, its furface becomes covered over with a green cruft, which is green oxide of copper. This oxidation never penetrates be- yond the furface. Copper is not attacked by water at the boiling tem- perature ; but if cold water be allowed to remain long on its furface, the metal becomes partly oxidated. Sulphur mixes readily with copper. The combina- tion may be formed by mixing the ingredients together and applying a pretty ftrong heat. Sulphuret of copper is brittle, fofter than copper, of a black colour exter- nally, and within of a leaden grey. It is compofed, ac- cording to Kirwan's experiments, of 8i parts of copper • Klrvian i3Xid I 9 of fulphur*. Mintr. ii, jj^r Pelletier formed phofphuret of copper by melting 5"^ ■ together one ounce of copper, one ounce of phofphoric •Phofphuret glafs, and one dram of charcoal. It was of a white of copper, colour. On expofure to the air, it loft its luftre and became blackifhf. Margraf was the firft perfon that formed this phofphuret. His method was to diftil phofphorus and brown oxide of copper together. It is formed moft eafdy by projedling phofphorus into red hot copper. According to Pelletier, it contains 20 % mj. xiii. parts of phofphorus and 80 of copper f . This phof- •3' phuret is harder than iron : It is not duftile, and yet cannot eafily be pulverifed. Its fpecific gravity is $ Sage 7,1220. It cryftallizes in tetrahedral prifms^. Journ. dt j_ Copper combines readily with gold when the two isxviii.468."'^*^'^ are melted together. The compound is of a 1 01 reddilli colour, more fufible than gold, but lefs duftile. The proportions of the ingredients which form this al- loy are not known ; nor would it be eafy to afceitain them, as the two metals are almoft equally fufible. The current gold of this country is compofed of 1 1 parts of gold and one part of copper. 2. The alloy of copper and filver is made as eafily as that of gold, and the properties are equally unknown. It is harder and more fonorous than filver. The cur- rent filver coin of Britain is compofed of 15 parts of f:lver and one of copper. + Ann. dt Chim. i. 74, Alloys of copper. S T R Y. Part 1. 3. Platinum combines readily with copper. The al- Iron. loy is mucli more fufible than platinum ; it is duflile, • •' hard, takes a fine polifh, and is not liable to tarnilli. This alloy has been employed with advantage for com- pofing the mirrors of reflefting tclefcopes. { 4. The amalgam of copper cannot be formed by fim- 1 ply mixing that metal with mercury, nor even by the application of heat ; becaufe the heat necelTary to melt copper fublimes mercury. Dr Lewis has given us fe- veral procefTes for forming this amalgam. One of the fimpleft is to triturate mercury with a quantity of cora- moQ fait and verdigrife ; a fubftance compofed of oxide of copper and vinegar. The theory of this procefs is not very obvious. loi . The affinities of copper are, according to Bergman, Its affiaitici as follows : Gold, Silver, Arfenic, Iron, Manganefe, Zinc, Antimony, Platinum, Tin, Lead, Nickel, Bifmuth, Cobalt, Mercuiy, Sulphuret of alkali. Sulphur, Phofphorus. Sect. VI. Of Iron. Iron, the moft abundant and moft ufeful of all the Difcovery metals, was neither known fo early, nor wrought fo of iron, eafily, as gold, filver, and copper. For its difcovery we muft have recourfe to the nations of the eaft, among whom, indeed, almoft all the arts and fciences firft fprung up. The writings of Mofes (who was born about 1635 years before Chrift) furnifli us with the umpleft proof at how early a period it was known in Egypt and Phoenicia. He mentions furnaces for work- , ing iron*, ores from which it was extraftedf ; ^'^^u'Deai ir t- tells us that fwordsj, knives J, axes||, and tools for jg. cutting ftones<^, were then made of that metal. Howf ZWJ. viii. many ages before the birth of Mofes iron muft have 9. been difcovered in thefe countries, we may perhaps con-J^^""Jg' ceive, if we rejleft, that the knowledge of iron was t LeVit. i. brought over from Phrygia to Greece by the Dadlyli*, 17. who fettled in Crete during the reign of Minos I. about II D«>"- I431 years before Chrift ; yet during the Trojan ^'^r, "'^"^^^^jj_ which happened 200 years after that period, iron was^ in fuch high eftimation, that Achilles propofed a ball* Htfod, aj of it as one of his prizes during the games which hequoiedby celebrated in honour of Patroclus (r). At that period C''"^.'. none of their weapons were formed of iron. Now if^ \- ' the Greeks iu 200 years had made fo little progrtfs in an art which they learned from others, how long niuft it Oy srpiv ^(v ptrrraaxi fjayoi tr^t^Cf HsTiMn^f A\\* l»T?( Toy i-Xi^ii CTO(fa;:XBf JiOf A^iXXtv/, r.» 104 Vs proper- ties. Viil. 105 Form 5 two oxides. f Ann. de Chim, xxiii. 85. and Ni- tholfort's ^otinial^ i. 45.i- X M.-m. A- caii ftjr, I7S2. la's The r affi- nities. ^LaGran^e. I Scbrichl. C H E M I it have taken the Egyptians, Phrygians, Chalybes, or whatever nation firft dilcovered the art of working iron, to have made that progrefs in it which vi'e find they hud done in the days ot Muics ? Iron, when frefh broken, is of a bluifh grey colour. It has a llyptic taite, and emits a fmell when rubbed. It is malleable and diittile in every temperature ; and its malleability is increafed in proportion as the tempe- rature augments. Its tenacity is fuch, that an iron wire Vo "^ ""^ '"^'^ ■" diameter fuilains a weight of 430 pounds without breaking *. Its hardnefs is fuch, that it may be eafily reduced to powder by the appllcntion of a iile. Its fpecific gra- vity is 7,788. It is iaiufible in the ilrongell heats hi- therto produced. It is attrafted by the magnet or loadflone, and is it- felf capable of becoming magnetic ; Init it retains this property only for a very ihort time. It is not hardened by being plunged into liquids while hot, nor foftened by being cooled flowly. Iron combines with oxygen very readily. When kindled in oxygen gas, it burns with great rapidity and fplendor, and is in this manner converted into an oxide. It is converted into an oxide alfo when iurrounded by nioill air, or when plunged in water ; becaufe it has a ftronger affinity for ox) gen than hydrogen has, and is therefore capable of decompofing water. Mr Prouit has lately proved, that there are only two oxides of iron, the green and the broivn or reel, and that all the other fuppofed oxides are merely mixtures of thefe two in various proportions f. The green oxide may be obtained by diffolving iron in fulphuric acid, and then precipitating it by potafs. It is a light, green-coloured, earthy-like fubftance, com- pofed, as Mr Lavoifier has fhewn, of 27 parts of oxy- gen, and 73 of iron %. Wlien this oxide is expofed to the air, it quickly abforbs more oxygen, and is con- verted into a brown powder, which i& the Ironun oxide, Mr Proull lias proved that it contains 52 parts of iron and 48 of oxygen. This oxide is well known under the name oi riijl of iron, which is generally, how- ever, or perhaps always, combined with carbonic acid gas. The affinities of thefe oxides, according to Bergman, are as follows : Gallic acid ? Oxalic acid, Tartarous, Camphoric §, Sulphuric, Saccholaftic, Muriatic, Pyroraucous ||, Nitric, Sebacic, Phofphoric, Arfenic, SuppL. Vol. I. Part. I. 107 S T R Y. Fluoric, Succinic, Citric, Formic, Laflic, Acetous, Boracic, Pruffic, Cirbonic. Iron unites readily with fulpl^ur. Sulphuret of iron, Sulpfiurct. formerly called pyrites, is found ready formed in many parts of the world. It is not eai'y to determine the proportions of its ingredients, becaufe it is capable of combining both with iron and fulphur, and confequent- ly, if there happens to be any excefs of either during its formation, it takes it up. Perhaps the proportions are not far from equal parts of fulphur and of iron. It is of a pale yellow or browniili colour, and is cflpable of afluming a cryllalline form. Its fpeciiic gravity is a- bout 4,000. When placed upon the fire it precipi- tates ; and at a red heat lofes its yellow colour, and be- comefi of an iron grey, excepting its furface, which is of a bright red. It melts at 102° Wedgewood in a covered crucible into a bluifh flag, fomewhat porous internally*. When expofed to air and moifture, \.\\t'^ Klr-wan't fulphur, as happens in all fulphurets, gradually abforbs •''^''"»■•"• oxygen, and is conyerted into an acid. 7*- If iron filings and fulphur be mixed together, and formed into a pafte with water, the fulphur decompofes the water, and abforbs oxygen fo rapidly, that the mix- ture takes fire, even though it be buried under ground. This phenomenon was firil difcovered by Homberg j and it is conlidered as afibrdiiig an explanation of the origin of volcanoes. The native fulphuret of iron has been obferved more than once to take iire on being fud- denly moiftened with water. Iron combines readily with phofphorus, and forms pj,^^! phojpljiiret of iron ; to which Bergman, who firil difco-rct°^ vered it, gave the name o(fidcrum. There is a particular kind of iron, known by the name of coldjhort iron, becaufe it is brittle when cold, though it be malleable when hot. Bergman was cm- ployed at Upfal in examining the caufe of this proper, ty, while Meyer was occupied at Stetin with the fame inveiligation ; and both of them dilcovered, nearly at the fame time, that, bjr means of fulphuric acid, a white powder could be feparated from this kind of iron, whf ;h by the ufual procefs they converted into a metal of a dark fteel grey, exceedingly brittle, and not very fo- luble in acids. Its fpecific gravity was 6,700 ; it was not fo fufible as copper ; and when combined with iron rendered it cold Jhort. Both of them concluded that this iubftance was a new metal ; and Bergman gave it the name oi fiderum. But Klaproth foon after recol. lefting that the fait compofed of phofphoric acid and iron bore a great refemblance to the white powder ob- tained from cold fliort iron, fufpefted the prefence of G g phofphoric Toy J' ttryir (v vvtio-j-f o-utf a.\\oi7i y-TtaTttrai. -OfVUtT^- , oi KXt TBTB af&K\J rrftptnTt^^C Kptuf^ivoi' u /ttfy y»p 01 arf^j3ajUfvo( ys trt^n^v Iliad, xxiii. 1. 826. • Fcllttlcr, jinn ds Chtm. I. 104. CHEMISTRY. Part I. To decide the lead it acquires this property by being immerfcd while If n. pornriie'combiiKd phofphoric acid and iron, and oh- ignited int.. a cold liquid : for this immcriion, though ' ^ ' iained, by heating it in a crucible along with charcoal it has no cffeft upon iron, adds greatly to the liardntfs powde'rf's), a fubltance exaftly r.fcmbling the new oi Jleel. , ' rn .u ci . 1 r Sect. V] II. Of Lead. Leid appears to have been veiy early known. It is mentioned feveral times by Mofes. The ancients feem to have confidered it as nearly related to tin. Lead is of a bluifii white colour, fomewhat darker p^g"^;- than tin. When newly melted it is very bright, but of lead, foon becomes tarnifiied bv expofure to the air. It has fcarcely any tatte, but emits on friftion a peculiar fmell. It is very malleable, and may be reduced to thin plates by the hammer ; but its duAility is very im- perfect : a wire of lead -r'otli of an inch in diameter is only capable of fupporting a weight of 2ij\ pounds*. * Mucjrm'j Its hardncfs is 5-f ; its fpecific gravity is i 1,3523:!:. 'J'^''""'"-}'; Its fpecific gravity is not increaftd by hanimerintr, nei. t/"'""''" .1 • , •. 1 I , . , •' ^ . , ,t>' Miner, n. ther eioes it become harder, as is the cafe with other me-ao2. tals : a proof that the hardnefs vshich metals alfume un-{ Bnjtn. der the hammer is in confequence of an incrcafeof denfity. It melts, according to Dr Lewis, at 540° Fahrenheit; according to the Dijon academicians, at 549^ When expofed to a violent heat it evaporates completely. When cooled (lowly, after being fufed, it cryftallizes. The Abbe Mongez obtained it in quadranguhir pyra- mids, lying on one of their fides. Each pyrr.inld was compofed as it were of three layers. Pajot obtained it in the form of a polyhedron with 32 fides, formed by the concourfe of fix quadrangular pyramids^. r rr^^ , Lead ftains paper or the fingers of a bluilh black co-I'hv/. ' lour. xxxviii, 5j. There is a (Irong affinity between this metal and oxy- '*' gen. When nitric acid is poured upon it, an effervef. " ''^'"''• cence enfues, owing to the decompofition of the acid ; the lead feizes oxygen from it, and is converted into a white powder, which may be obtained pure by evapo- rating it to drynefs, and then wafliing it in pure water. This is the luhile oxide of lead. It is compofed of about 95 parts of lead and five of oxygen ||. The aflrnities|| Klrwan'! of this oxide are, according to Bergman, as follows : Miner, ii.. Sulphuric acid, 4J9' Sebacic, Saccholadlic, Oxalic, Arfenie, Tartarous, Phofphoric, Muriatic, ' ■ ■ Benzoicj <238 Levi. Benzoic (u) ? ■ ■ » Siilpliurous, Suberic ?1 / v Zoonic > I ^''' Nitric, Pyroniucous (v) ? Fluoric, Citric, Formic, Laftic, Acetous, Boracic, Prufilc, Carbonic, Fixed alkali. When lead is expofed to heat in contaft with air, its furface is foon covered with a grey pellicle ; when this is taken off, another foon forms : and in this manner the whole lead may foon be converted into a dirty grey powder, which feems to be the white oxide mixed with a little lead. When this powder is heated red hot, it af- fumcs a deep yellow colour. This is t.\\t yellow oxide oi lead, formerly called majjicot. If the heat be continued, the colour is gradually changed to a beautiful red. This is the red ox'ule of lead, formerly called mi/iium. It is conipofed, as Lavoifier has (hewn, of 88 parts of lead * ATcn:. and 1 2 of oxygen *. Par. J7Si. The manner in which thefe changes are brought about is evident ; the metal gradually abfovbs oxygen from the atmofphcre. This has been aftually proved by experiment. Thefe oxides (if they really differ in the proportion of oxygen) refemble acids in feveral of their properties. They are very eafily converted into glafs by fufion. Scheele has fhewn that there is alfo a iroti'i! oxide of lead, which contains more oxygen than ii6 any of the others. Suljihuret, Sulphur unites eafily to lead by fufion. The fulphu- ret of lead is brittle, of a deep grey colour, and much Itfs fuiible than lead. Thefe two fubftances are often found naturally combined ; the compound is then called galena. Sulphuret of lead is compofed, according to the experiments of Wenzel, of 868 parts of lead and 132 ^ Kirtvanj of fulphurf. Mhiir. ii. Phofphuret of lead may be formed by mixing toge- ^^^' ther equal parts of filings of lead and phofphoric glafs, Phofphu- ''"'^ fufuig them in a crucible. It may be cut with a rtt, knife, but feparates into plates when hammered. It is of 3 white filver colour with a (hade of blue, but it foon tarni(hes when expofed to the air. This phofphuret may alfo be formed by dropping phofphorus into melt- ed lead. It is compofed of about 12 parts of phof- % Pellitisr, phorus and 8b of lead J. "f?"' *... Lead combines with mod of the other metals. ' ' I. Little is known concerning the alloy of lead and 128 gold. It is faid to be brittle. Alloys, an i CHEMISTRY. Part I. 2. The alloy of filver and lead is very fufible, and t.t:.d. neither elallic nor fonorous 3. Platinum and lead unite in a ftrong heat the ' Fourcre^\ loy is brittle, of a puiplifh colour, and foon changes on expofure to the air *. 1 4. Mercury, when poured upon melted lead, dlffolves it' readily. The amalgam is white and brilliant, and alTumes a folid form. It is capable of cryftallizing. The cryftals are compofed of one part of lead and one and a half of mercury f. f nij^n A- 5. Copper and lead combine eafily by fufion ; but the '"dimUian^ alloy has not been apphed to any ufe. J 6. Iron does not unite with lead. ^ 7. Lead and tin may be combined by fufion. The alloy in the proportion of two parts of lead and one of tin is more foluble than either of the metals feparately. It is accordingly ufed by plumbers as a folder. jj. Lead, when taken internally, adls as a poifon. Its Afl5mtie* affinities, according to Bergman, are as follows : Gold, Silver, Copper, Mercury, Bifmuth, Tin, Antimony, Platinum, Arfenic, Zinc, Nickel, Iron, Sulphuret of alkali, Sulphur, Phofphorus ? j,q The ancients gave to the fcven metals lad defcribed Names and (omitting f/iUinum, which they did not know) the namesT^''" of the planets, and denoted each of them by particular ^[^^^^°] marks, which rcprefented both the planet and the metal, by the an- Gold was the Sun, and reprefented by 0. cients. Silver the Moon, J). ?. d". ■y. h- It feems moft probable that thefe names were firft given to the planets ; and that the fevcn metals, the only ones then known, were fuppofed to have fome re- lation to the planets or to the gods that inhabited them, as the number of both happened to be the fame. It appears from a palTage in Origen, that thefe names firft arofe among the Perfians (w). Why each particular metal was denominated by a particular planet it is not eafy to fee. Many conjeftures have been made, but fcarcely any of them are fatisfaftory. As Mercury Copper Iron Mercury, Venus, Mars, Tin Lead' Jupiter, Saturn, (u) Benzoat of lead is decompofed by muriatic acid. Trommfdorf, Ann. de Chim. xi. 317. (;/) Suberic acid decompofes nitrat of lead. Qze Jamefon's Mineralogy, ^. 166. Zoonic acid produces the fame effect, as Berthollct has obfevved. (v) Schrickel places it after the three mineral acids. (w) Contra Celfiim, lib vi. 2 2. — " Celfus de quibufdam Perfarum myfteriis ferraonem facit. Harum rerum, in- quit, aliquod reperitur in Perfarum doftrina Mithracifque eorum myfteriis veitigium. In illis enim dux cjeleftes converfiones, alia llellarum fixarum, errantium alia, et animas per eas tranfitus quodam fymbolo reprasfentantur, quod hujulmodi eft, Scala altas portas habens, in fumma autcm oi^ava porta. Prima portarum plumbea, altera llanaea, »o the ai- ologer 131 Aecnrdtng to the al- Part r. C H E M l.eaii. As to the charaflers by which thefe metals were cx- * ' ' " ' prefTed, adrologcrs ieem to have confiJered them as the Oriinii of attributes! of the deities of the fame name. The circle thefc marksin the earliell periods among the Egyptians was the accnrdiiii; fyrabol of divinity and perfcflion ; and ieems with great propriety to have been chofen by them a^ the character of the fun,efpecially as, when furrounded by fmall ftrokes projefting from its circumference, it may form fome re- prefentation of the emilfiou of rays. The femicii'cle is, in like manner, the image of the moon ; the only one of the heavenly bodies that appears under that form to the naked eye. The chararo- cefs of time was converted into cuf'rum. AVhen thefe changes took place is not known accurately. Plinv i.lir. cyprium, lib. xxxvi. c. 26. The word cuprum occurs firlt in Spartian, who lived about the year 290. He lays in his life of Caracalla, cancelli ex are vel cupro. (c) Mr Roux indeed, who at the requefl of Count Caylus analyfed an ancient mirror, found it compofecl of copper, lead, and antimony. This would go far to convince us that the ancients knew this metal, provided it could be proved that the mirror was really an ancient one ; but this point appears to be ejttieraely doubttu!. 242 CHEMISTRY. Part I. Antimony, procefs. To him indeed we are indebted for our ac- *— V quaintance with many of the properties of this metal. Antimony is of a white colour, with a (hade of grey. • Fourcrcy. It has a fcnlible tafte, but no fmell *. '43 It is neither malleable nor dudile, but exceedingly Pro(>crties jj|.;jj|g_ jts ipecitic gravity, according to BrifTon, is of amimo- ^^^^^ _ according to Bergman, 6,860. Its hardncfs is ikirnv^n-s 6,5 f. It melts at 809° Fahrenheit |. If after this the Minir.U. jj^at be increafed, the metal evaporates. On cooling it *''l affumes the form of oblong cryllals, perpendicular to } £,rgma^. ^^^ i„t^,.„ai f„rface of the veffel in which it cools. It is to this crydallization that the laminated flrudure which antimony always affumes is owing. Neither air nor water liave much effeft on this metal. Itsoilde- When antimony is beat to powder, and expofed for fome time to a gentle heat, it abforbs oxygen, and is converted into a grey powder. This is the giry oxide of antimony. When this metal is kept for fume time melt- ed in contaa with air, it fublimes in the form of a white powder, formerly called/now or luhite Jlowers of anti- mony. This is the white oxide of antimony. This oxide may be procured alfo by pouring nitric acid on antimo- my, and then evaporating to drynefs. Antimony at- trafts the oxygen from the acid, and thus palfes very rapidly into the ftate of an oxide. This oxide feems to confid of about 77 parts of antimony and 23 of oxy- 5 Klrwan's ^„ f The nature of thefe oxides has never yet been '"■"" "- accurately inquired into. It is not even known at pre- fent whether the white oxide obtained by heat and that obtained by nitric acid contain the fame quantity of oxygen. The experiments mentioned by Mr Kirwan make the contrary probable || ; and yet thefe oxides have too many qualities in common to render thefe ex- periments conclufive. The white oxide of antimony is foluble in waterf ; and when fufed, is converted into a tranfparent glafs. The white oxide obtained by nitric acid feems to poffefs many of the properties of an acid. The afTuiities of the grey oxide of antimony are, ac- cording to Bergman, as follows : Sebacic acid, Muriatic, Benzoic (d) ? Oxalic, Sulphuric, Pyromucous *, Nitric, Tartarous, Saccholaflic, Phofphoric, Citric, Succinic, Fluoric, Arfenic, Formic, Laftic, Acetous, Boracic, Pruffic, Carbonic. Sulphur combines readily with antimony. This com. pound is often found native : it was formerly called an. timony, and the pure metal was then called regulus of Miner, ll 489 II nid. ^ Rouelte, * Sel/rideL 145 Sulphurets, antimony. Sulphuret of antimony is eafily melted by a Antimony, moderate heat : if the heat be continued, the fulphur '~~^ fublimes, and at the fame time the antimony abforbs oxygen, and Is converted into a grey oxide. This ful- phurct is compofed of 74 parts of antimony and 26 of fulphur*. * Bergman, The grey oxide of antimony is alfo capable of combi-iii' idj. ning with about tsjj of fulphur. This compound, by fufion, may be converted into glafs. It was formerly ufed in medicine under the name of g/afs of antimony. 146 When equal parts of antimony and phofphoric glafs P'lofphu- are mixed togetlier with a little charcoal powder, and"^^'' melted in a crucible, phofphuret of antimony is produ- ced. It is of a white colour, brittle, appears laminated when broken, and at the frafture there appear a luimber of fmall cubic facettes. When melted it emits a green flame, and then fublimes in the form of a white powder. Phofphuret of antimony may likewife be prepared by fufing equal parts of antimony and phofphoric glafs, or by dropping phofphorus into melted antimony f . f Pelleiier, Antimony is capable of combining with raoft of the-^""- <''• metals _ ^'^^''' »'"• 1. Gold may be alloyed with antimony by fnfing ' . them together. The antimony is afterwards feparable Alloys, by an intenfe heat. This alloy is little known, and has never been applied to any ufe. 2. The alloy of filver and antimony is brittle, and its fpecific gravity, as Gellert has obferved, is greater than intermediate between the fpecilic gravities of the two metals which enter into it. 3. Platinum eafily combines with antimony. The alloy is brittle, and much lighter than platinum :j:. The ( Dr Leviii. antimony cannot afterwards be completely feparated by heat. 4. Mercury does not ealily combine with antimony. Mr Gellert fucceedcd in amalgamating this metal by putting it into hot mercury, and covering the whole with water. J. Copper combines readily with antimony by fufion. The alloy is of a beautiful violet colour, and its fpeci- fic gravity is greater than intermediate §. j CelUrt. 6. Iron combines with antimony, and forms a brittle Tiard alloy, the fpecilic gravity of which Is lefs than in- termediate. The magnetic quality of iron is much more dlminlfhed by being alloyed with antimony than with any other metal ||. | ij, 7. The alloy of tin and antimony is white and brittle ; its fpecific gravity is Icfs than intermediate ^. ^ y. 8. When equal quantities of lead and antimony are fu- fed, the alloy is porous and brittle : three parts of lead and one of antimony form a compacfl alloy, malleable, and much harder than lead: 12 parts of lead and one of antimony form an alloy very malleable, and a good deal harder than lead : 16 parts of lead and one of an- timony form an alloy which does not differ from lead except in hardnefs *. This alloy forms printers types, n, Gmelw ■ g. Zinc and antimony form a brittle alloy, the {•fi.cx- Aim.de fie gravity of which is lefs than Intermediate f. The Chim. viii. alloys of antimony are little known. Gellert is almoft^',?" the only pcrfon who has examined them. It would re- qiu're a great number of experiments to be able to fix the proportions of their ingredients. The t GellaU (d) Muriatic acid decompofcs benzoat of antimony. Tromnfdorf, Ann, de Chim, xi. 317. Part I. Bil'iniith. 148 Properties of biimuth. • Kirtvan^ \ Brijin. 149 Its oxides, § Kifwan , h/lirur. ii. 489. II Ihid. C H E M The affinities of antimony are, according to Berg- man, as follows : Iron, Copper, Tin, Lead, Nickel, Silver, Bifmuth, Zinc, Gold, Platinum, Mercury, Arfcnic, Cobalt, Sulphiiret of arfenic. Sulphur, Pliofphorus? Sect. XL Of Difmulh. The ancients appear to have known nothing of bif- muth, nor do we know who difcovercd it ; but it is firft mentioned by George Agricola, who was boru about the end of the 15th century. Bifmuth is of a yellowifli or rcddilh white eolour, and . alraoft deftitute both of tafte and fmell. It is brittle. Its hardnefs is 6*. Its fpecific gra- vity is 9,8z27t. It melts at 460" Fahrenheit f. Wlien heated in clofe veffels, it fublimes. When al- lowed to cool flowly after fufion, it cryftallizes. Bifmuth is not altered by water. When expofed to the air it foon tarniflies. When bifmuth is kept fufed in contaft with air, it is gradually oxidated. When heated red hot, it emits a very faint blue flame, and its oxide evaporates in the form of a yellowifli fmoke. When this fmoke is colleft- ed, it is found to confift of a brown coloured powder. This is the brown oxide of bifmuth. It is compofed of about 94. parts of bifmuth and 6 of oxygen $. Bifmuth decompofes nitric acid with great rapidity, by attiadl- ing its oxygen. If the quantity of acid be conlider- able, it diifolves the oxide as it forms ; but the greater part of it may be precipitated by diluting the acid with water. This precipitate, which is a white powder, is while oxide of bifmuth. It is compofed of about 84 parts bifmuth and 16 of oxygen ||. The affinities of the oxides of bifmuth are, according to Bergman, as follows : Oxalic acid, Arfenic, Tartarous, Phofphoric, Sulphuric, Sebacic, Muriatic, Benzoic (e) ? Nitric, Fluoric, Saccholadlic, Succinic, Citric, I S T R Y. Formic, Laftic, Acetous, Pruffic, Carbonic, Ammonia. Birmuch. 150 Sulphur combines readily with bifmuth by fufion. 3 uiphuret. The fulphuret of bifmuth is of a bluifli grey colour, and cryftallizes into Ijeautifnl tetrahedral needles. It is com- pofed of 85 parts of bifmuth and 15 of fulphur*. • IVenzel, There appears to be little affinity between bifmuth^'';""'"/ and phofphorus. Mr Pellelier attempted to produce ^'"'"'- "• the phofphuret of bifmuth by various methods without ,', , fucccfs. When he dropped j)hofphoru;, however, into Phofphu- bifmuth in fufion, he obtained a fubftance which did not ret, apparently dilfer irom bifmuth, but which, when expo- fed to the blow-pipe, gave evident figns of containing phofphorus. Phofphuret of bifmuth, according to Pel- letier, is compofed of about 96 parts of bifmuth and four of phofphorus f . M'"'- * Bifmuth combines readily with mofl; of the metals. "^"- ^"'* 1. Equal parts of bifmuth and gold form a brittle al- ,"jj loy, nearly of the fame colour with biimuth:};. Alloys, 2. Equal parts of bifmuth and filver (xjrm alio a l^rittle t K"'"' , alloy, but lefs fo than the lafl. The fpecific gravity of ^^^'?""' ' both thefe is greater than intermediate Ji. § /i,,/. 3. The alloy of bifmuth and platinum is alfo very brittle. When expofed to the air it afl'umes a purple, violet, or blue colour. The bifmuth may be feparated by heat II . \iDrLiivi,. 4. Mercury difliolves bifmuth very eafily. The amal- gam is more fluid than pure mercury, and has the pro- perty of diflblving lead and rendering it alfo fluid ^. It^ Cramer. is capable, however, of cryftallizing. The cry Hals are either otlahedrons, lamellated triangles, or hexagons. They are compofed of one part ot bifmuth and two of mercury *. * '-■^'"'' ^'' 5. The alloy of copper and bifmuth is not fo red as^""' '• ^* copper. 6. Nothing is known concerning the alloy of iron and bifmuth. 7. Bifmuth and tin unite readily. A fmall portion of bifmuth increafes the brightnels, hardnels, and fono- roufnefs of tin : it often therefore enters into the com. pofition of the compound called pewter. Equal parts of tin and bifmucii form an alloy that melts at 280° : eight parts of tin and one of bifmuth, melt at 390": two parts of tin and one of bifmuth, at 330°!. \ Dr Lewru 8. The alloy of lead and bifmuth is of a dark grey colour, a clofe grain, but very brittle. 9. Bifmuth does not combine with zinc. 10. The alloy of antimony and bifmuth is unknown. Bifmuth likewife enters into triple compounds with metals : Two parts of lead, three of tin, and five of bifmuth, form an alloy which melts at the heat of boil- ing water, which is 2 1 2°. is3 The affinities of bifmuth, according to Bergman, are And afBni- as follows : '"' Lead, Silver, Gold, H h 2 Mercury, (e) Muriatic acid decompofes benzoat oi biita^lh.—'Tromm/Jor/, /inn. de Cb'm. xi. '317. C H E IM Mercury, Antimony, Tin, Copper, Platinum, Nickel, Iron, Sulphuvei of alkali, .Sulphur, Phofphorus ? Sect XII. Of Arjtmc. The word arfenic (af5-i«i,o») occurs firft in the works of Diofcorides, and of fome other authors wlio wrote about the beginning of the Chriftian era. It denotes in their works the fame fubilance which Ariftotle had called cutia^a-^Y, (f), and his difciple Theophraftus apcitiyi; which is a reddifh coloured mineral, compofed of arfenic and fulphur, ufed by the ancients in painting, and as a medicine. The ivhite oxirJe of arfenic, or wbat is known in com- merce by the name of arfenic, is mentioned by Avicen- na in the nth century ; but at what period the metal called arfer.ic was firft extrafted from that oxide is un. known. Paracelfus feems to have known it. It is ■pif ntioned by Schroeder in his Pharmacopoeia publilhed * Birgman, in 1 649 *. ii. 27S. Arfenic, when pure, is of a bluifh white colour, [t is „ '■'•^ . exceedinglv brittle. Its hardnefs is 7+. Its fpecific cf arfenic. gravity S.JIoJ. i Kirzuan, When expoled to the temperature of 354° in clofe veffels it fublimes ^, and cryilallizes in regular tetrahe- drons. It is not much altered by water. Boiling water, how- ever, is capable of diflblving, and retaining .r_L__th of arfenic ; but that pan of the metid is no doubt reduced to the ftate of an oxide l|. When arfenic is expoled to the open air, it very foon lofes its luftre, and is gradually converted into a erevift black fvibftance by combining with oxygen. This is called the grey oxide of arfenic. When expofed to a moderate heat in contaft with air, it fublimes in the form of a white powder, and at the fame time emits a fmell rcfembling garlic. If the heat be increafed, it burns with an obfcure bluifh flame. This fiiblimate is •white oxide of arfenic, which is compo- 5 Kir-wan'i {ed of 93 parts of arfenic and 7 of oxygen ^. iWwtr. 11. jj jj ^jf 2 (},arp acrid tafte, which at laft leaves an im- preflion of fweetnefs, and is one of the moll virulent poifons known. It has an alliacious fmell. It is fo- luhle in bo parts of water at the temperature of 60'', * Bergman, zni in 15 parts of boiling water*. When this folu- + B ' dt *'°" '^ evaporated, the oxide cryftallizes f. When Ali. Upfal, heated to 283*, it fublimes : if heat be applied in clofe 1 733. veffels, it becomes pellucid like glafs, but when expofed to the air it foon recovers its former appearance. The fpecific gravity of this glafs is 5,000 ; that of the white } Btr^CTu/i, oxide, 3,706 J. This oxide is capable of combining 'sji. ays. vvith moil of the metals, and in general renders them brittle. Its af&nities, according to Bergman, are as follows : Mine,, u. li. 278. { JliJ. 154 Its oxidec, I H^jbrenuin, Chrn. At, I7SS, i. i8i. 1 S T R Y. PartT. Muriatic acid, , Arfenic. ^ Oxalic, '' Sulphuric^ Nitric, Sebacic, Tartaro'js, Phofphoric, Fluoric, Saccholaftic, Succinic, Citric, Formic, Laftic, Arfenic, Acetous, Pruffic, Ammonia, Water, Alcohol ? Arfenic, or rather the white oxide of arfenic, is ca- pable of combining with an additional dofe of oxygen. The compound produced is arfenic acid, firft difcovered by Scheele, which contains 91 parts of arfenic and 9 of oxygen*. * Bertbdlei, Arfenic combines readily with fulphur. When heat A/r'aan", is applied to a mixture of white oxide of arfenic and ' '""' "' fulphur, the oxide is decompofed, part of the fulphur n-^ combines with its oxygen, and the remainder unites Suiphurct, with the reduced metal. The fulphuret of arfenic pro- duced by this procefs is of a yellow colour, and was for- merly called orpiment. It is compofed, according to Wcftrum, of 20 parts of arfenic and 80 of fulphur f. It is often found native. If a ftronger heat be applied, .'„j fo as to melt the fulphuret, it affumes a fcarlet colour, and is much kfs volatile than formerly. This new com- pound was formerly called realgar. It is compofed, ac- cording to Weftrum, of 80 parts of arfenic and 20 of fulphur J. The difference therefore between it and or- ' "'*• piment is evident. During the fufion part of the ful- phur without doubt fublimes. It might be called red fulphuret of arfenic. 156 Arfenic combines readily with phofphorus. The Phofphu- phofphuret of arfenic may be formed by diililling equal''"' parts of its ingredients over a moderate fire. It is black and brilliant, and ought to be preferved in water. It may be formed likewife by putting equal parts of phof- phorus and arfenic into a fufficient quantity of water, and keeping the mixture moderately, hot for fome time §. § PMitler, Arfenic unites with moft metals, and in general ren- ■^": ders them more brittle and more fufible. ' 1. Melted gold takes up ^'^th of arfenic ||. The al- p b. loy is brittle and pale. ikii. 2. Melted filver takes up Tjth of arfenic f. The al-^ -''•''■ loy is brittle. Alloys, 3. The alloy of platinum and arfenic is brittle and very fufible. It was firft formed by Scheffer. The arfenic may be feparated by heat. 4. The amalgam of arfenic is compofed of five parts of mercury and one of arfenic *. * ^^'^• 5. Copper takes u'p |-ths of arfenic f. This alloy is \ ItiJ. white ; f JClr-wan't \Uner. ii. .d! Chim. Xlii.' ngna% (f) Pliny feems to make a diftinftion between fandaracha and arfenic. See Lib. xxxiv. c. 18. Part r. Cobalt « Ccllert. \'Bergman, Ann. de Chim xiii. 139- 5 Kirivan 3 £ Bergman, JbiJ. 11 UiJ. And ^Di- ti£5. f AB. Up. 159 PrpJlrIti«S •f mhr-.lt, '*^-LcQnhatdh ^ Kirivan s fdiner, ii. 168. X Bergman y IT. C H E M white ; and when the quantity of arfenic contained in it is fmail, both duftile and malleable *. It is called ivhile tombac. 6. Iron is capable of combining with more than its own weight of arfenic •)•. This alloy is white, brittle, and capable of cryftallizing. It is found native \. 7. The alloy of tin and arfenic is harder and more fo- norous than tin, and has much refemblance externally to zinc. Tin often contains a fmall quantity of ar- fenic. 8. Lead takes up ~th of arfenic J. The alloy is brittle and dark coloured. q. Zinc takes up fth of arfenic, antimony ^th, and bifmuth -rVth II . The affinities of arfenic, according to Bergman, arc as follows : Nickel, Cobalt, Copper, Iron, Silver, Tin, Gold, Platinum, Zinc, Antimony, S'jlphuret of alkali, Sulphur, Phofphorus. Sect. XIII. Of Cobalt. A MINERAL called cobalt (g), of a grey colour, and ▼ery heavy, has been ufed in different parts of Europe fmce the 15th century to tinge glafs of a blue colour. From this mineral Brandt obtained in 1733 ^ '"^"' ^'^- tal, to which he gave the name of cobalt ^. Cobalt is of a white colour, inclining to a bluiih or ftecl grty. When pure, it is fomewhat malleable while red hot *. Its liardnefs is 8 f-. Its fpecific gravity is 8,15 (h). It requires for fufion a heat at lealt as great as call iron, which melts at 130° Wedgewood. No heat has been produced great enough to volatalize itf. Cobalt, when pure, does not feem to be afltdtcd by air or water. It is attra a light violet colour. 8. Cobalt does not combine with lead by fufion. 9. The alloy of zinc and cobalt is not formed with- out difficulty. JO. The alloy of antimony and cobalt is unknown. J I . Cobalt does not combine with bilmuth by fu- fion *. 12. Arfenic combines very readily with cobalt. The alloy is brittle, mucli more fufible, and more ealily oxi- dated than pnre cobalt-|-. The affinities of cobalt are as follows ; Iron, Nickel, Arfenic, Copper, Gold, Platinum, Tin, Antimony, Zinc, Siilphuret of alkali, ' Sulphur, Pofphorus ? Sect. XIV. Of Nich!. A HEAVY mineral of a red colour is met with in fe- veral parts of Germany, which bears a ftrong refem- blance to an ore of copper; but none of that metal can be extrafted from it : for this reafon the Germans call- ed it hupfer nickel (devil's copper). Hierne mentioned it in 1694. Cronlledt was the I'lrft chemift who exa- mined it with accuracy. He concluded from his expe- riments, which were yubliflied in the Stockholm Tranf- aftions for 1751 and 17^4, that it contained a new me- tal, to which he gave the name of nickel. Some chemills, particularly Mr Sage, affirmed, that it contained no new metal, but merely a compound of various known metals, which could be feparated from each other by the ufual procefies. Thefe alTertions in- duced Bergman to undertake a very laborious courfe of experiments, in order if poffible to obtain nickel in a (h: 1 of purity : for Cronftedt had not been able to fe- parate a quantity of arfenic, cobalt, and iron, which adhered to it with much obllinacy. Thefe experiments have been very fully detailed in the article Chemistry, in the Encycl. to which be beg leave to refer. Berg- man has fliewn, that nickel poiTefles peculiar properties, and that it can neither be reduced to any other metal, nor formed artificially by any combination of metals. It mull therefore be confidered as a pecuhar metal. It may poflibly be a compound, and fo may likewlfe many other metals ; but we muft admit every thing to be a peculiar body which has peculiar properties, and we muft admit every body to be fmiple till fome proof be aftually produced that it is aj^ompound ; otherwife we forfake the road of fcience, and get i-nto the regions of fancy and romance. I S T R Y. Parti. Nickel is of a greyifii white colour, and when lefs Nickel. ■ pure inclines a little to red. '"■"">• ■' It is both duftile and malleable. Its hardnefs is 8*. ,. ' T c ■/• • . r •/•/-,- Its proper- its Ipecihc gravity 9, coof. It requires tor tuhon aiies, temperature at Icill equal to i ?o° Wedgewood f. * Kii-wmU It is powerfully attrafted by the magnet, and is even ^^^""■'■- 'i- pofieffed of the property of attrafting iron. This in- , „ duced Bergman to fuppofe that nickel, when pureft,ii. jj,. ' was ilill contaminated with about one-third of iron : f JiiJ. but as this is the only proof of its containing iron, Klnproth, with reafon, deems it an iafufficient one, and confiders attradlion by the magnet as a property of nickel §. 5 /?„„. j: When expofed to a ftrong heat, nickel is oxidated cli^. i. flowly. Its oxide is of a brown colour ; if impure, it '7°- is greeny]}. The oxide of nickel, according to Klaproth, oxides is compoied of 77 parts of nickel and 23 of oxygen ^.^ Kim-m't Its affinities, according to Bergman, are as follows ; Miner, ii. Oxalic acid, 490- Muriatic, Sulphuric, Tartarous, Nitric, Sebacic, Phofphoric, Fluoric, SaccholaAIc, Succinic, Citric, Formic, Laftic, Acetous, ^ Arfenic, Boracic, Pruffic, Carbonic, Ammonia, Potafs .' Soda ? jgj Cronftedt found that nickel combined readily with Suiphuret fulphur by fufion. The fulphuret which he obtained was yellow and hard, with fmall fparkling facets ; but the nickel which he employed was impure. Nickel combines very readily with phofphorus, either pi,ofnhu- by fufing it along with phofphoric glafs, or by drop-r^t, ping phofphorus into it while red hot. The phofphu- ret of nickel is of a white colour, and when broke ex- hibits the appearance of very flender prifms coUefted together. When heated, the phofphorus burns, and the metal is oxidated. It is compofed ot 8:? parts of nickel and 17 of phofphorus *. The nickel, however, iin* Pdutltr, which this experiment was made, was not pure. '^i"- d' Little is known concerning the alloys of nickel wlth'^'-""' '""• other metals. Equal parts of filver and nickel form a "' ,-0 white dudtile alloy. Equal parts of copper and nickel Alloys, form a red duftile alloy. The compounds which this metal forms with tin and zinc are brittle. It does not combine with mercury f. It has a very ftrong afSnityf Bergman, for iron, cobalt, and arfenic, and is fcarcely ever found"- 251. except combined with fome of them. Its af&nities, according to Bergman, are as follows : ^ndVlEni- Iron, Cobalt, Arfenic, Copper, Part L C H E M r'7'i Difcovery Iiefc-. * Bergman, ii. 211. 17-2 Its proper- ties, ■^ Kirtvan j Joiner, lu a88. 173 Oxides ^ Bergman, Ji. »3J, Copper, Gold, Tin, Antimony, Platinum, Bifmulh, Leud, Silver, Zinc, Siilplmrct of alkali. Sulphur, Popfphorus ? Sect. XV. Of Mansamfe. The dark grey mineral called man^anefe, in Latin magtiefia (according to Boyle, from its rtfemblance to the magnet), has been long known and ufed in making glafs. A mine of it was difcovered in England by Mr Boyle. It was long iuppofed to be an ore of iron ; but Port and Cronftedt having denionllratcd that it contain- ed very little of that metal, the latter referred it in his Mineralogy to a diltinft order of earths, which he call- ed terrs magnefia. Bergman, from its fpecific gravity, and feveral other qualities, fufpefted that it was a me- tallic oxide : he accordingly made feveral 'attempts to reduce it, but vyithout fuccefs ; the whole mafs either alTuming the form of fcoriae, or yielding only fmall fe- parate globules attrafted by the magnet. This difficul- ty of fufion led him to fufpeft that the metal he was in queft of bore a ftrong analogy to platinum. In the mean time, Dr Gahn, who was making experiments on the fame mineral, aijtually fucceeded in reducing it by the following procefs : He lined a crucible with char- coal powder moiftened with water, put into4t fome of the mineral formed into a ball by means of oil, then filled up the crucible with charcoal povviler, luted ano- ther crucible over it, and expofed the whole for about an hour to a very intenfe heat. At the bottom of the crucible was found a metallic button, or rather a num- ber of fmall metallic globules, equal in weight to one- third of the mineral employed*. It is eafy to fee by what means this reduftion was accomplifned. The char- coal attrafted the oxygen from the oxide, and the me- tal remained behind. This metal is called manganefe. Manganefe is of a greyilh white colour. It is not malleable, and yet not fo brittle as to be eafily broken. Its hardnefs is 8 f . Its fpecific gravity is 7,000 \. Its fufion requires fo great a heat, that it has been vefy fcldora accomplifhed. When reduced to powder, it is attrafted by the magnet. AVhen expofed to the air, it very foon tarnifhes, and affumes a darker colour, till at lad it becomes black and friable. This change is produced by the abforption of oxygen. It takes place much more rapidly if heat be applied to the metal. The fubilance thus obtained is the black oxide of manganefe. This oxide is found in great abundance in nature, though fcarcely ever in a ftate of purity. It is compofed of 75 parts of manga- nefe and 25 of oxygen §. I S T R Y. 247 If a quantity of tniiriatic acid be poured upon this Manganefe. oxide, and heat applied, part of the acid combines with ^"^ ' fome of the oxygen of the oxide, and flies off in yellow fumes. The oxide is dilfolved in the reft. If potafs be added to this folution, a white powder is precipitated. This is the ivhifs oxide of manganefe. It contanis, ac- cording to Bergman, about 80 parts of manganefe and ao of oxygen. It foon attrafts more oxygen when ex- pofed to the air, and is converted into black oxide. The affinities of the white oxide, according to Berg, man, are as follows : Oxalic acid, Citric, Phofphoric, Tartarous, Fluoric, Muriatic, Sulphuric, Nitric, Saccholaftic, Succinic, Sebacic, Tartaric, Formic, Laftic, Acetous,, Fruffic, Carbonic. The fulphuret of manganefe is unknown. ,^4 Phofphorus may be combined with manganefe by Phofphu- melting together equal parts of the metal and of phof-'''' phoric glafs ; or by dropping phofphorus upon red hot manganefe. The phofpluiret of manganefe is of a white colour, brittle, granulated, difpofed to cryftallize, not altered by expofure to the air, and more fufible than manganefe. Wh-en heated, the phofphorus burns and the metal becomes oxidated *. * VelUtler, Manganefe combines readily with carbon by fu- '^"'•- <>' fion (i). •a.>..xiii. Little is known concerning the alloys of manganefe. j,. It combines readily with copper. The compound, ac-Carburet, cording to Bergman, is very malleable, its colour is red, 176 and it fometimes becomes green by age. Gmelin mado ■'^"°y'« a number of experiments to fee whether this alloy could be formed by fufing the black oxide of manganefe along with copper. He partly fucceeded, and propofed to fubltitute this alloy inftend of the alloy of copper and arfenic, which is ufed in the artsf. We believe, how- f Ann. dt ever, that upon trial the new alloy has been found not C^'ot. u to anfwer. ^°^' Manganefe combines readily with iron ;, indeed it has fcarcely ever been found quite free from fome mixture of that metal. It combines alfo very eafily with arfe- nic and tin, not eafily witli zinc, and not at all with mercury \. \ Bergman, The affinities of manganefe, according to Bergman, 'i-*"- are as follows : AndYffini- Copper, jigj_ Iron, Gold, Silver, (i) Bergman, III. 379. — Sometimes manganefe is very fpeedily oxidated by expofure to the air; fometimes fcarcely altered by it, as Klaproth and Pelletier have obferved. Mr Kirwan fuppofes that the manganefe which is foon altered contains carbon, and that tbis is the caufe of the diS'erence. See Miner. II. 2 88< 178 . t>ifc-- When heated by the blowpipe upon charcoal, it burns with a very lively flame of a blue colour, inclining at the edges to green. It is fo volatile as to rife entirely in a whitifli grey fmoke ; at the fame time It exhales a dif- agreeable odour like that of radlfhes. This fmoke is the white oxide of tellurium, which may be formed alfo by dlfl^olving the metal In iiitroinurlatic acid, and pour- ing into the faturated folutlon a quantity of water : a white powder precipitates, wlilcli is the oxide ||. " II Kl''f"tli. When this oxide is heated tor fome time in a retort, it melts, and appears, after cooling, of a yellow ftraw colour, having acquired a fort of radiated texture. When I i formed (l) Blende is tTie name given to ores of zinc. (m) From Uranus (oujawo^), the name given by Mr Bode to the new planet difcovered by Herfchel ; which name the German aftronomers have adopted. Mr Klaproth c^.lled the metal at firft uranile ; but he afterwards changed that name for uranium. (n) Mr Kirwan, in the new edition of his Mineralogy, which was publiflied before Mr Klaproth's experi- ments were known, gives this metal the name of Syhanite. — Tellurium exifts in fevcral other mines in the fame Tnountalns. CHEMISTRY, formed into a pafte with any fat oil, and diftllled in a When placed on red hot cliarcoal, the metal burns as ' ' red heat, brilh'ant metallic drops are obferved to cover well as the fulphur with a blue flame, the upper part of the retort, which at intervals fall to Tellurium amalgamates with mercury by fimple tritu- the bottom of tlie veflel, and are immediately replaced rationf. — Theotherpropertie5ofthismetalareunknown.j by others. After cooling, metallic fixed drops are found adhering to the fides and at the bottom of the A new metal has lately been difcovered by Vauquclin ( veiTel ; the remainder of the metal is reduced. Its fur- in the red lead ore of Siberia. It is grey, very hard, face is brilliant and almoft always cryftallized. When brittle, and eafily cryftallizes in fmall needles J. Het this oxide Is expofed to heat on charcoal, it is reduced has given it the name oi chromum (o). ♦ iT/a/iro/i. with a rapidity that refembles detonation ♦. We have now defcribed all the metals at prefent' TeUurium combines with fulphur. The fulphuret of known. The following table will exhibit in one view this metal is of a grey colour and radiated ftvufture. their principal properties. Metal*. Colour. 4ara- nefs. Specific gravity Fuling Point. 32W.(P) 1398 F. Mallea- bility. Duaility Gold. Yellow. 6 7t 19,300 28 2000 500 270 Silver. . White. IO,J10 28 W. 1C44 F. 160000 Platinum. White. 23,000 150W..? above 500 Mercury. White. 13,568 -39 F- Copper. Red. 8 8,870 27 W. 1449 F. 299J Iron. Blue-grey. 9 7,788 150W. 20577 F. 450 Magnetic. Tin. White. 6 5 6 6i 6 7 7.299 410 F. 2000 49 Lead, Blue-white. 11.352 540 F. 29i Zinc. White. 7,190 700 F. Antimony. Grey. 6,860 700 F. Bifmuth. Yellow-white. 9,822 460 F. Arfenic. White. 8,310 400 F. ? Cobalt. White. 8 8 8,150 9,000 130 W. 17977 F. Magnetic. Nickel. White. 150 W. 20577 F. Magnetic. Manganefe. White. 8 6 7,000 150 W. 20577 F. Magnetic. Tungften. Brown. 17,600 Molybdenum Grey. 7,500 Uranium. Grey. 6 6,440 Titanium. Red. 9 4,180 Tellurium. White. 6,115 540 F. Chromum. Grey. (o) From xri"'' becaufe it poffefles the property of giving colour to other bodies in a remarkable degree. \t) W. Wedgewood's pyrometer. F. Fahrenheit's thermometer. We Part I. C H E M Chhn. xxiu. €5.— A^i- thoijln's Jcur/t. i. Tellurium. V.'c liave fccii tliat ali the metals arc capable of com- ^-—v—— bining with oxygen ; that almoll every one forms va- Remarks '""'"^ oxides, containing different quantities of oxygen, on metallic and varying in colour and other properties according to oxides. tlie proportion of oxygen which they contain. No part of chemillry has more engaged the attention of philo- fophcrs tlian the metallic oxides ; and yet fuch is the difficulty of the fubjeft, that fcarcely any part of che- iTiillry is more imperfectly underllood. We neither know how many oxides every particular metal is capable of forming, nor the manner in which they are formed : neither have the dhferenccs between oxides of the fame metallic bale been inquired into ; thougli there cannot be a doubt tliat they differ, not only in their affinities, but in many of their other pro- perties. The -white oxide of manganefe, for inllance, combines readily with acids, but the black is incapable of uniting with any. Mr Proud, in a very valuable paper which he lately * Am.de publiflied concerning the oxides of iron*, hints that metals are only capable of two degrees of oxidation, or, which is the fame thing, that only two difierent oxides can be produced from the fame metal. We think he has proved this completely as far as iron is concerned ; and probably the obfen-ation holds good with refpeA to many other metals. Arfenic, copper, tin, molybde- num, and perhaps even mercury, feem to be capable of only two degrees of oxidation ; but it would require a ■very numerous and accurate fet of experimcntb to be able to determine the matter, or even to form a pro- bable conjefture. Analogy is certainly againll the fup- pofition ; for it has been demonftrated that fome fub- ftances at lead are capable of combining with three dif- ferent dofes of oxygen (cl)> and why may not this be the cafe alfo with the metals ? There is one obfervation, however, which we owe to Mr Proud, the truth of which cannot be doubted, and which is certainly of the higheft importance — that me- tals are not capable of indetinite degrees of oxidation, but only of a certain number ; and that every particular oxide confids of a determinate quantity of the metal and of oxygen chemically combined. Iron, for inftance, is not capable, as has been fuppofed, of uniting with oxygen in all the intermediate degrees between tVs and ^~, and confequently of forming 20 or 30 different oxides ; it can only combine with precifely -^-^ parts, or ^^ parts, and with no other proportions ; and there- fore is only capable of forming two oxides, the green and the brown. In like manner, every other metal com- bines with certain proportions of oxygen, and forms cither two oxides or more according to its nature. To talk therefore of oxidating a metal indefinitely is not accurate, except it be intended to fignify the combi- ning of part of it with oxygen, while the red remains in its natural date. If iron be oxidated at all, it mull be combined with -i^-'- of oxygen ; if it be oxidated more than this, it muft be combined with xsV oi oxygen. We beg leave to add another obfervation, which we confider as of no lefs importance, and which will ferve in fome meafure to modify and explain what has been juft now faid. Oxygen is capable of uniting with me- I S T R Y. 251 tals, or with any other fubftance for which it has an Telljrium. affinity, only in one determinate proportion. Iron, for in- ' v ' ftance, and oxygen can only combine in the proportion of 73 parts of iron and 27 of oxygen. Thefe two quan* tities laturatc cacli other, and form a compound which is incapable of receiving into it any more oxygen or iron : this compound is the green oxiJc of iron. How comes it then, it will be alked, that there is another oxide of iron, the broiun oxide, which contains 52 parts of iron and 48 of oxygen, proportions certainly very different from 73 and 27 ? We aufwer, there is an af- finity between the green oxide of iron and oxygen ; they are capable of combining together, and of faturating each other in the proportion of about 71,5 parts of green oxide and 28,5 of oxygen ; and the compound which they form is the Irotun oxide, which of courfe contains 52 parts of iron and 48 of oxygen : But then it is not formed by the combination of thele two fub- ftances direftly, but by the combination of the green oxide and oxygen. In like manner, the arfenic acid is not compofed of arfenic and oxygen combined direiftly, but of white oxide of arfenic combined with oxygen. The vei"y fame thing takes place in all the other metals. We cannot at prefent prove the truth of this obferva- tion in a fatisfaSory manner, becaufe it would be ne- ceffary to draw our proofs from combinations which are yet uridefcribed ; but we will have occahon to confider it afterwards. We have feen that all the metals hitherto tried are capable of combining with fulphur, except gold and titanium ; that all of them on which the experiments have been made can be united with phofphorus ; and that three of them, iron, zinc, and manganefe, united with carbon ; and perhaps many more of them may hereafter be found capable of affuming the form of car- burets. We have feen, too, that they are capable of uniting with one another and forming alloys. This was long rec- koned peculiar to metals, and it is at prefent one of the bed cviterions for determining the metallic nature of any fubdance. Much is wanting to render the che- midry of alloys complete. Many of them have never been examined ; and the proportions of alniod all of them are unknown. Neither has any accurate method been yet difcovered of determining the affinities of me- tals for each other. The order of af5,nities which we have given for each metal was determined by Bergman ; but he acknowledged himfelf that he wanted the pro- per data to enfure accuracy. Chap. IV. 0/" Earths. The word earth, in common language, has two mean ings ; it fomctimes fignifies \}\t globe which we inhabit, and fometimes the mould on which vegetables grow. Chemifts have examined this mould, and have found that it confids of a variety of fubdances mixed together without order or regularity. The greated part of it, however, as well as of the ifones, which forni apparently fo large a proportion of the globe, confids of a fmall number of bodies, which have a variety of commmon pro- I i 2 perties. (q^) We (hall fee afterwards that azot is one of thefe. 191 Pr >iLr!ic5 ct tatths. llIEC, C H E M I perties. Thcfe bodies chemifts have agreed to clai's to- gether, and to denominate larths. Everv body which poflclTts the following properties is an tcrth : 1. Infolable in water, or nearly fo ; or at leail be- coming infoluble when combined with carbonic acid. 2. Little or no tafte or fmell ; at leaft when com- bined with carbonic acid. ^. Incombuftible, and incapable while pure of being altered by the fire. 4. A fpecific gravity not exceeding 4,9. 5. When pure, capable of afTuming the form of a white pow'der. The earths at prefent known amount to ten ; the ^nsmes of which are, liir.e, magnefia, barytcs, ftrontitts, alumina, fiiica, jargonia, glucina, yttria, aguftina. Every one of the above charafteriilics is not perhaps rigoroufly applicable to each of thefe bodies ; but all of them polTefs a fufficient number of common properties to render it ufeful to arrange them under one clafs. Sect. I. Of Lime. Lime has been known from the earlieft; ages. The ancients employed it in medicine ; it was the chief in- gredient in their mortar ; and they ufed it as a manure jn, to fertilize their fields. Method of It abounds in many parts of the world, or perhaps procuring we fhruld rather fay, that there is no part of the world where it does not exift. It is found pureft in lime- ftones, and marbles and chalk. None of thefe fubllances, however, is, llriftly fpeaking, liifie ; but they are all capable of becoming lime by a well-known procefs, by keeping them for fome time in a white heat : this procefs is called the burning of lime ; the produti; is denominated quicklime. This lait fubftance is what we call lime. Pure limJ is of a white colour, moderately hard, but eafily reduced to a powder. It has a hot burning tafte, and in fome meafure cor- rodes and deftioys the tfxture of thofe animal bodies to which it is applied. It has no fmell. Its fpecific gra- * KirwansVltJ is 2,3 *. Miner, i. J. if water be poured on newly burnt lime, it fwells and falls to pieces, and is foon reduced to a very fine powder. In the mean time, fo much heat is produced, that part of the water flies of in vapour. If the quan- tity of lime flacked (as this procefs is termed) be great, the heat produced is fufSicient to fet fire to combuftibles. In this manner veffels loaded with lime have fometimes been burnt. When great quantities of lime are flacked in a dark place, not only heat, but light alfo is emitted, iJcur.Je as Mr Pelletier has obferved +■ When flacked lime is J'ivf.t.s.i- weighed, it is found to be heavier than it was before. This additional weight is owing to the combination of part of the water with the lime ; which water may be feparated again by the apphcation of a red heat ; and by this procefs the lime becomes juft what it was before i Dr Bhti. being flacked J. Six hundred parts of water, at the temperature of 60", diffolve about one part of lime ; boiling hot water diffolves about double that quantity §. This folution is called ime-mater. It is limpid, has an acrid tafte, and changes vegetable blue colours to green. One ounce troy of lime-water contains about one grain of Ume. 194 _ Properaes of lime. .195 Lime-wa- ter. 5 Kirwiin^s THiiur. i. 5 S T R Y. Part I. One thoufand parts of lime are capable of abfovbing, Lime. and retaining, at a heat of 600°, 228 parts of water*. ~"^ . -' Lime has never yet been obtained in the ttate of "i*"'' cry Hals. It is incapable of being fufed by the moft violent heat that can be produced in furnaces, or even by the mod powerful burning-glaiTes. jtjg Lime unites readily with fulphur, and forms y'u^iur^'/Sulphuret, of lime. This compound may be obtained by niixing^""^ un.Oacked lime and flowers of fulphur together, and adding a little water. The heat produced by the flack- ing t)f the lime is fufficient to make the fulphur and the lime unite. This fulphuret is of a red colour. When water is poured on it, fulphurated hydrogen gas is emitted. The fulphur is gradually converted into fulphuric acid by uniting with the oxygen of the water, the hydrogen of which flies off in the form of gas, dif- folving at the fame time a part of the fulphur. j.- It is capable alfo of combining with phofphorus. — Phofphurei The phofphuret of lime decompofes water by the affift- of lime, ance of a moderate heat, and gives out phofphurated hydrogen gas. .^g Limeflone and chalk, though they are capable of be- Caufe of ing converted into lime by turning, pofTefs hardly any tiie diffe- of the properties of that aftive fubilance. They aie""'-'^ 'f' taflelefs, fcarcely foluble in water, and do not pf rcep- j^^j^g ^^^ j tibly aft on animal bodies. Now, to what are the newimie, properties of lime owing ? What alteration does it un- dergo in the fire ? It had been long known that limeflone lofes a good deal of weight by being burned or calcined. It was na- tural to fuppofe, therefore, that fomething was iepara- ted from it during calcination. Accordingly, Van Hel- mont, Ludovicus, and Macquer, made experiments in fucceffion, in order to difcover what thai fomething was; and they concluded from them that it was pure -water, which the lime recovered again when expofed to the atmofphere. As the new properties of lime could j hardly be afcribed to this lofs, but to fome other caufe. According Stahl's opinion, like all the other chemical theories oftoStahli that wonderful man, was generally acceded to. He fuppofed that the new properties which lime acquired by calcination, were owing entirely to the more minute divifion of its particles by the aftion of the fire. Boyle indeed had endeavomed to prove, that thefe properties were owing to t\te fixation of fire in the lime : a theory which was embraced by Newton and illuftrated by Hales, and which Meyer new modelled, and explained with fo much ingenuity and acutenefs as to draw the attention of the moll diftinguifhed chemifts. But while Meyer was thus employed in Germany, Dr Black, of Edinburgh, publifhedthofe celebrated experimentswhich form fo brilliant an era in the hiftory of chemiftry. j^^ He firft afcertained that the quantity of water fepa- Explained rated from limeftone during its calcination was not near-byDrBlack- ly equal to the weight which it lofL He concluded in confequence that it muft have loft fomething elfe than mere water. What this could be, he was at firft at a lofs to conceive ; but recoUefting that Dr Hales had proved, that limeftone, during its folution in acids, emitted a great quantity of air, he conjeftured that this might probably be what it loft during calcination. He calcined it accordingly, and applied a pneumatic appa- ratus to receive the produft. He found his conjefture verified ; 'artl. C H E M Lime, verified ; and that the air and lie water which fepara- -— V ' ted from the lime, were together precifely equal to the lofs of weight which it had fuflained. Lime therefore owes its new properties to the lofs of air; and limtftone differs from lime merely in being combined with a certain quantity of air : for he found that, by reftoring again the fame quantity of air to lime, it was converted into limeftone. This air, becaufe it exiflcd in lime in a fix- ed ilate, he called Jixed air. It was afterwards exami- ned by Dr Prieftley and other philofophers, found to poffefs peculiar properties, and to be that fpecies of gas now known by the name of carbonic acid gas. Lime then is a fimple fubftance, that is to fay, it has never yet been decompounded ; and limeftone is compofed of carbonic acid and lime. Heat feparates the carbonic acid, and leaves the lime in a ftatc of purity. The affinities of lime, according to Bergman, are as follows : Oxalic acid. Suberic (r) ? Sulphuric, Tartarous, . Succinic, Phofphoric, Saccholaftic, Nitric, Muriatic,. Sebacic, Fluoric, Arfenic, Formic, La£lic, Citric, Benzoic, Sulphurous, Acetous, Boracic, Nitrous, Carbonic,- Pruffic, Sulphur, Phofphorus,, Water, Fixed oil. Sect. IL Of Magnefa. About the beginning of the eighteenth century, a Roman canon expofed a white powder to fale at Rome a» a cure for all difeafes. This powder he called mag- nejja alba. He kept the manner of preparing it a pro- found fecret ; but in i 707 Valentini informed the pub- lic that it might be obtained by^calcining the lixivium which remains after the preparation of nitre ; and two I S T R Y. 253 years after, Slevogt difcovered that it might be prcci- Magnelia.^ pitated by potafs from the mother ley (s) of common ' fait. This powder was generally fuppoled to be lime, till Frederic Hoffman oblerved that it formed very dif- ferent combinations with other bodies *. But little was • Bfrgmjn, known concerning its nature till Dr Black publifhed his i. 305. celebrated experiments in 1755. Margraf publini<;d a differtalion on it in 1759, and Bergman another in 1775, in which he collefted the ol)l'crvatioiis of thefe two philofophers, and which he enriched alfo with many additions of his own. - ^^, As magnefia has never yet been found native in a Methmi of ftate of purity, it may be prepared in the following procuring manner: Sulpliat af magnefia, a fait compofed of this"' earth and fulphuric acid, exifts in fea- water, and in ma- ny fprings, particularly fome about Epfom, from which circumftancc it was formerly called Epfom fait. This fait is to be difl'olved in water, and half its weight of potafs added. The magnefia is immediately precipita- ted, becaufe potafs has a ftronger affinity for fulphuric acid. It is then to be wafhed with a fufficient quantity of water, and dried. Magnefia thus obtained is a very foft white powder, jt^ p,opgr„ which has very little tafte, and is totally deflitute of tits, fmcll. Its fpecific gravity is about 2,3 f. ^ K!r-war's It is foluble in about 7900 times its own weight of-^^'"""- '■ *• water at the temperature of 60° J. j juj. Even when combined with carbonic acid (for which it has a ftrong affinity) it is capable of abforbing and re- taining 14^ times its own weight of water, without let- ting go a drop ; but on expofure to the air, this water evaporates, though more flowly than it would from lian-. Magnefia has never yet been obtained in a cryllalli- zed form. It tinges vegetable blues of ati exeedingly fliglit green. It is not melted by the ftrnngeft heat which it has been pofilble to apply ; but Mr D' Aicet obferved that, in a very high temperature, it became foinewhat agglu- tinated. When magnefia and fulphur are put into a veffel of water, and kept for fome time expofed to a moderate heat, they combine, and form fulphuret of magnefia ; which, according to Fourcroy, is capable of cryftalli- zing. The phofphuret of magnefia has never been examined • Equal parts of lime and magnefia mixed togetlier, Effeift of and expofed by Lavoifier to a very violent heat, did not heat "" of lime and ■ melt ; neither did they melt when Mr Kirwan placed them in the temperature of 1 50° Wedgewood. Tlie,^^ j^^jj^ following Table, drawn up by Mr Kirwan from his own experiments, fhcws the effect of heat on thefe two earths mixed together in different proportions. Proportions. (r) The affinity of this acid for lime is inferior to the oxalic, which decompofes the fuberat of lime, ya- mefon's Mineral, of Shetland and /Irran, p. 168. (s) The mother ley is the liquid that remains after as much as poflible of any fait has been obtained from it. Common fait, for inflance, is obtained by evaporating fea-water. After as much fait has been extracted from a quantity of lea-water as will cryflallize, there is iliil a portion of liquid remaining. This portion is t'.ie mother lev. 354 Magnefil, C H E M I Propoitioii.s, -■'H.at. ■■' Eflea. 80 Lime 20 Mag. i50°We(lg. Went through the crucible. 75 Lime 25 Mag. 160 Went through the crucihle. 66 Ijime 33 Mag. Went through the crucible. 20 Lime ho Mag. 165 Did not melt. 33 Lime 66 Mag. 138 Did not melt. 30 Lime 10 Mag. 156 Melted into a fine greenifh yellow gla.s; but the crucible was corroded throughout. 406 ,. n Affinities of The affinities of magnefia, according to Bergman, are magnefia. 33 follows ; Oxalic acid, Phofphoric, Sulphuric, Fluoric, Sebacic, Arfcnic, Saccholaftic, Succinic, Nitric, Muriatic, Tartarous, Citric, Formic, La&ic, Benzoic, Acetous, Boracic, Sulphurous, Nitrous, Carbonic, Pruffic, Sulphur, Phofphorus ? Water. Sect. IIL Of Barytes. A ^-ERY heavy mineral is found in Sweden, Germa- ny, and Britain, which Margraf coiifidered as a com- pound of fulphuric acid and lime. But Schecle and Gahn analyfed it in 1774, ^f"^ found that it cnnfillcd of fulphuric acid combined with a peculiar fpecies of earth. This analyfis was foon after confirmed and ex- tended by Bergman. The earth was at firft called terra ponderofa, heavy earth, on account of the great fpecific gravity of the fubllance from which it was obtained. Morveau called it borate (from eapv;, heavy), which Bergman changed into barytes ; and this lalt term is now univerfally adopted. 107 Difcovery of barytes. S T R Y. Parti. Barytes is generally found combined eitlicr with ful- Barytes. jihuric or carbonic acid. From the firft of theie conv '~~^ "^ pounds, which is by far the moll common, it may bej^^'^^^ ^ ^ obtained by the following procefs : obtaiuing Reduce the mineral to a powder and mix it with 2 ^ it- its weight of carbonat of foda (t), previoufly deprived of all its water. Expole the mixture to a red heat for an hour and a half, avoiding fufion, and a double de- compofition takes place ; the fulphuric acid unites with the foda, while the carbonic acid combines with the ba- rytes. Walh it in a fufficient quantity of water to dif- folve the compound of fulphuric acid and foda, the car- bonat of barytes, which is almoft infoluble, remains be- hind. Left it (hould be mixed with fome other earths, which is generally the cafe, boil it for three hours in ten times its weight of diftilled vinegar, the fpecific gra- vity of which is 1,033 ; by which the barytes will be difiolved, and likewife the lime and magnefia, if there happen to be any; but every other earth (u) remains untouched. Pour off the folution, and add to it ful- phuric acid as long as any precipitate is formed. This precipitate confifts of the whole barytes and the lime (if there be any) combined with fulphuric acid. Wafli it in 50 times us weight of water, and all the lime will be diffolved. There will now remain nothing but bary- tes combined with fulphuric acid, which may be decora- pofed as before by carbonat of foda *. The carbonic *A/s'!iet'un, acid may then be feparated by applying a very violent^""- ^5.. heat f ; or, what is better, nitric acid may be poured , ^' '"■ upon it, which will feparate the carbonic acid and com- £j,„ Tranf. bine with the barytes ; and then the nitric acid may beiv. 36. driven off by a moderate heat J". t ^"ir"^ Bary tes thus obtained i, a light, fpongy, porous bo- ^" ji",Tdc dy, which may be very eallly reduced to powder. It c/j/m. ixi. has a harfli and more cauftic taftc than iime; and when 276. ' taken into the ftomach, proves a moft violent poifon. *°9 It has no perceptible fmell. Its fpecific gravity has not yet been afcertained. It imbibes water with a hiffmg noife, but, according to Dr Hope, without fvvelling or fplitting as lime does ^. However, wlien expoted to the air, as Four- 5 FJ'tx. croy and Vauquelin inform us, it efBorelces, cracks, '^runf. ibid. burfts, fwells up, heats, and becomes white, by abforb- ing moifture]]. I| Ann.d: Cold water diffolves about ^^xh. part of its weight of ''''"■ '^''■ barytes, and boiling water more than half its weight. ° , 'cy„„,,' As the water cools, the barytes is depofited in cryllals,,^/ 1.335. the (hape of which varies according to the rapidity with which they have been formed. When moft regular, they are flat hexagonal prifms, having two broad fides, with two intervening narrow ones, and terminated at each end by a four-fided pyramid, which in fome inltances conftitutes the larger part of the cryftal. When formed flowly, they are diftintl and large ; but when the water is faturated with barytes, they are depofited rapidly, and are generally more (lender and delicate. Then, too, they are attached to one another in fuch a manner as to affume a beautiful foliacious appearance, not unlike the leaf of a fern f . ^ Ho/f, iM Thefe cryftals are tranfparent and colourlefs, and ap- pear to be compofed of about 53 parts of water and 47 of Its proper- ties. (t) Soda is an alkali, which ftiall be afterwards defcribed. Carbonat of foda is foda combined with carbonic acid, the common ftate in which it is obtained ; potafs might alfo be ufed. (n) Except ftrontites, which Pelletier has deteAed in this mineral. Part I Baryre«. St'ontitCJ. • //. and Vauque- Itn^ ibiJ, iio Sulphuret cf barjtef. J Faurcfcy. 5 Lavoiper ^ Ac^d. Par. 311 Its affinu tics. CHEMISTRY. ofbarytes. "WTieti espofcd to the heat of boiling wa- ter, they undergo iht watery fuji on, or, which ib the 6ect. IV. Of Slronliles. fame thin^, they melt without loling any of the water About the year 1787, a mineral was brought to^^i/.'* which they contain. A ftronger heat makes the water Edinhurgb, by u dealer in foffils, from tlie lead mine of,,f'ltron^ fly oir. When expofed to the air, they attrattcaibo- Strontian in Argylrfhire, where it i,s found imbedded cites. ric acid, and crumble into dull. They are foluble in in the ore, mixed witli feveral other fi.bllances. It is 174 parts of water at the temperature of 60° ; but boil- fometimcs tranfparcnt and colouilefs, but generally has jng water difTolves any quantity whatever : the rcafon a tinge of yellow or green. Its liardnefs is c. Its fpe- of wliich is evident; at that temperature tlieir own wa- cific gravity varies from 3,4 to 5,726. Its texture is ter of cryllallization is fsfficient to keep them in folu- generally tihrous; and fometimcs it is found cryftallized tion *. _ in flendcr prifmatic columns of various lengths*. « fT„A, £, Water faturated with barytes is called barytic lualer. This mineral was generally confidered as a carbonate-". Iri/i/:' It has the property of converting vegetable blues to a ofbarytes; but Dr Crawford haviu"- obferved fome'v-44- green- _ differences between its folution in muriatic acid and tliat When barytes is expofcd to the blowpipe on a piece ofbarytes, mentioned in his treatife on Mur'iat of Bury - of charcoal, it fufes, bubbles up, and runs into globules, tes, publiihed in 1790, that it probably contains a new which quickly penetrate the cliarcoal \. This is pro- earth, and feiit a fpecimen to Mr Kirwan that he might .bably in confequence of containing water; for I, avoifier examine its properties. Dr Hope had alfo fufpedted found barytes not affeded by the Urongell beat which that its balls diflertd from barytes; and accordinfrly he he could produce. made a let of experiments on it in 1791, which were Barytes combines readily with fulphur. The eafieft read to the Royal Society of Edinburgh in J702. way of forming fuiphuret of barytes is to mix eight Thefe experiments fully proved that it contained a pe- parts of fulphat of barytes with one part of pounded culiar earth. Mr Kirwan likewifc analyfed the ftron- charcoal, and to apply a ftrong heat. The charcoal tian mineral, and drew precifely the fame conclufions. combines with the oxygen of the fulphuric acid, and It has been analyfed alfo by Mr Klaproth of Berlin, the compound flies off in the form of carbonic acid gas. and Mr Pelletier of Paris. It confifts of carbonic acid There remains behind fulphur combined with barjtes. combined with a peculiar earth, to which Dr Hope gave Sulphuret of barytes is foluble in water : It is of a yel- the name oijlrcntites. This appellation we fliall adopt. The c;irbonIc acid may be feparated by a heat of low colour. It is capable of cryftallizing ; and then affumes a yellowilh white colour J. The phofphuret of barytes has not been examined. No mixture of barytes and lime, nor of barytes and magncfia, is fufible in the ftrongell heat which it has been poffible to apply §. 140° Wedgewood, and then the ftrontites remains be- l""dt- . ^Kir-wan't Strontites has been found in Argylefhire in Scot--^'"""-'- land, near Briftol in England, and in Pcnnfylvania f . It^^^^} has been found alfo in France and in Sicily. It is of a;: r„T"''' The affinities of barytes, according to Bergman, are white colour. It has a pungent acrid tafte. When as follows 2'3 Sulphuric acid. Oxalic, Succinic, Fluoric, Phofphoric, Saccholaftic, Suberic (v) ? Nitric, Muriatic, Sebacic, Citric, Tartarous, Arfenic, Fluoric, Laftic, Benzoic, Acetous, Boracic, Sulphurous, Nitrous, Carbonic, Pruffic, Sulphur, Phofphorus, Water, Fixed oils. ties. Hope, ihidt PMclitr. pounded in a mortar, the powder that rifes is ofFenfive 'ts proper to the noftrils and lungs §. It is not poifonous ||. One hundred and fixty-two parts of water, at the temperature of 6c°, dilTolve nearly one part of it. The folution is clear and tranfparent, and converts vegetable blues to a green. Hot water diflblves it in much lar- ger quantities; and as it cools the ftrontites is depofited in colourlefs tranfparent cryftals. Thefe are in the form of thin quadrangular plates, generally parallelograms, the largeli of v. hich feldom exceeds one-fourth of an inch in length. Sometimes their edges are plain, but they oftener confill of two facets, meeting together and forming an angle like the roof of a houfe. Thefe cry- ftals generally adhere to each other in fuch a manner as to form a thin plate of an inch or more in length and half an inch in breadth. Sometimes they affume a cu- bic form. They contain about 68 parts in 100 of wa- ter. They are foluble in 51,4 parts of water, at the temperature of 60". Boiling water difi"olves nearly half its weight of them. When expofed to the air, they lofe their water, attrad carbonic acid, and fall into pow- When ftrontites is thrown into water, it attrads it«/y with a hiffing noife, much heat is produced, and it falls into powder much more rapidly than lime *. It combines with fulphur either by fufion in a cru- cible, or by being boiled with it in water. The ful- phuret (v) Suberic acid decompofes muriat and nitrat of barytes. Jamefon's Mineral, of Shetland and ^rran. CHEMISTRY. Part r. phurct Is of a Jark yellowifh brown colour. It is fo- luble in water*. Tiic airiLiities of ftrontitcs, 3S afcertained by Dr Hope, are as follows : Sulpluiric acid, Oxalic, Tartarous, Fluoric, Nitric, Muriatic, Succinic, Pholphoric, Acetous, Arfenic, Boracic, Carbonic. Sect. V. Of Silica. IIS TVTerhnd of obtaining filica. «i6 Its I roj^tr- ties. f Kivwans Jliiiitr.i. lo. t Hid. j Ibid. 1! ScUeU. ^ Kir*wans JMin. i. J4I. There are two methods of imitating thefe cryftaU by Si ica. avt. Tlie tirll metliod was difcovered by Bergman. He ' v ■■' dilTolvtd iilica in fluoric acid, the only acid in which it is folublo, and allowed the folution to remain undlilurb- td for two years. A number of cryftals were then found at the bottom of the vcffLl, moftly of irregular figures, but fome of them cubes with their angles trun- cated. They were hard, but not to be compared in this refpeft with rock cryfta! *. * Bctgmae, The other method was difcovered by accident. Pro."-3J- feflor Seigling of Erfurt had prepared a liquor fihcum, ■which was more than ufually diluted with water, and contained a fuperabundance of alkali. It lay undifturb- ed for eight years in a glafs veffel, the mouth of which was only covered with paper. Happening to look to it by accident, he obferved it to contain a number of crj'ftals ; on which he fent it to Mr Trommfdorft, pro- feffor of chemlftry at Erfurt, who examined it. The If one part of powdered flints or fand, mixed with liquor remaining amounted to about two ounces. Its three parts of potafs, be put into a crucible, and kept furface was covered by a tranfparent crull, fo ftrong in a ftate of fufion for half an hour, a brittle mafs will that the veffel might be inverted without fpilling any be formed almoft as tranfparent as glafs, which quickly of the liquid. At the bottom of the veffel were a num- attrafts moillure from the atmofphere, and is entirely ber of cryflals, which proved on examination to be ful- fohible in water. This folution k called /iqi/orji/icum, phat of potafs and carbonat of potafs (w). The cruft or liquor of Jiinls. It was firft accurately defcribed by on the top confided partly of carbonat of potafs, partly Glauber, a themift who lived about the middle of the of cryilallized filica. Thefe lafl. cryfl;als had aflumed the j^th century. form of tetrahedial pyramids in groups ; they were per. If an acid be poured into this liquor, a white fpongy feflly tranfparent, and fo hard that they ftruck fire fubllance is precipitated, which may be purified from with fteel f . \ Nkhal- tvery accidental mixture by walhlng it m acids, muria- Silica endures the moft violent heat without altera-yi"'' Jour/i, tic acid for inftance. This fubftaiice is called _/?//Vfo«j tion. ^'7- tarlh or plica. It was firft djftlnguifhed as a peculiar It feems incapable of combining with fulphur or phof- earth by Pott in 1741^, though it had been known long phorus. before ; and Carthcufer, Schcele, and Bergman, proved i. The e'feft of heat upon lime and filica, mixed in£(f^.^ pj- in fucceflion that it could not, as fome chcmifts had fup- various proportions, will appear from the following ex- heat on pofed, be reduced to any other earth. periments of Mr Kirwan J. mixtures of Silica, when dried, is a foft white powder, without either tafte or fmell. Its fpecific gravity is 2,66 f. It is Infoluble in water except when newly precipita- ted from the liquor filicum, and then one part of it is foluble in 1000 parts of water J. It has no effeft on vegetable colours. It is capable of abforbing about one-fourth of Tts weight of water, without letting any drop from it ; but on expofure to the air, the water evaporates very readily J. Silica may be formed Into a parte with a fmall quaii- tity of water : this pafte has not the fmalleft duftillty, and when dried forms a loofe, friable, and incoherent mafs 11 . Silica is capable of afluming a cryftalline form. Cry- . ftals of it are found in many parts of the world. They 5. Equal part of magnefia and filica melt with great Mj^^^fj^ are known by the name oi rock cryflal. When pure difficulty into a white enamel when expofed to the moft andYilica : they are tranfparent and colourlefs like glafs : they af- violent heat which can be produced $. They are infu-§ Lamifur, fume various forms; the moft ufual is a hexagonal fible in inferior heats in whatever proportion they are ■™"- ■'"'"■• prifm, furmounted with hexagonal pyramids on one or mixed ||. J98. " both ends, the angles of the prifm correfponding with 3. The effeft of heat on various mixtures of barytes 2,9 thofe of the pyramids. Their hardnefs is very great, and filica w^U appear from the following experiments of Barytesand amounting to eleven. Their fpecific gravity is 2,653 f. Mr Kirwan ^. ll".^** d proportions. |l,jJ,X;,. 17S0, p. .13. ^ Mineral. 'SJ- 4 Proportions. Heat. iiffcd. 50 Lime 50 Silica 150° Wedg. Melted into a mafs of a white colour,femitranfparent at the edges, and ftriking fire, tho' feebly, withfteel: itwasfome- what between porcelain and enamel. 80 Lime 20 Silica .56 A yellowifli white loofe pow- der. 20 Lime 80 Silica 156 Not melted, formed a brittle mafs. lime and filica ; I ]\iir.eral. i.ili. (w) Potafs, combined with fulphuric acid and witL carbonic acid. Part I. CHEMISTRY. ^51 Silica. I'roi'orticin';. Heat. fffcd. 80 Silica 20 Barytes 1550 Wcdg. A white brittle mafs. 75 Silica 20 Barytes 150 A brittle hard mafs, femi- tranfparcut at the edges. 66 Silica 33 Barytes 150 Melted into a hard fome- what porous porcclaiu mafs. 50 Silica 50 Barytes 148 A hard mafs not melted. 20 Silica 80 Barytes 148 The edges were melted into a pale greenifh mat- ter between a porcelain and enamel. 25 Silica 75 Barytes 150 Melted into a fomewhat porous porcelain mafs. 33 Silica 66 Bar)'tes 150 Melted into a ycllowiih and partly greenifh white porous porcelain. tzo And lime, magnefia, aiid lilica. • Mim. Berl. ibid, and Jour, de J'tyf- ixiv. an Affinities of filica. Method of obtaining alumina. 313 Its proper- ties. ^ Kirwan^s fitter . i. 9- 4. The effeft of heat on mixtures of ftrontites and filica is not known. 5. It follows from the experiments of Achard, that equal parts of lime, magnefia, and iilica, may be melted into a greenidi-coloured glafs, hard enough to Itrike fire with fteel ; that when the magiieila exceeds either of the other two, the mixture will not melt; that when the filica exceeds, the mixture feldom melts, only indeed with him in the following proportions ; three fiiica, two lime, one magnefia, which formed a porcelain ; and that when the lime exceeds, the mixture is generally fu- fible*. The affinities of filica are as follows : Fluoric acid. Fixed alkali. Sect. VL Of Alum'wa. Dissolve alum in hot water, and add to the folu- tion potafs as long as any precipitate is formed. De- cant off the fluid part, and wa(h the precipitate in a fufficient quantity of water, and then allow it to dry. The fubftance thus obtained is called alumina. Its pro- perties were nril afcertained with accuracy by Mar- Alumina thus obtained is a very white fpongy pow- der, without any fmell or tafte. Its fpecific gravity is 2,00 f. It is fcarcely fdluble in water, but may be diffufed through it with great faci- lity. SuppL. Vol. I. Part I. With a fmall quantity of water it forms a very tough Alnmina. duiilile paile, and does not readily mix with more. » In its ufual Hate of drynefs it is capable of abforbing 2\ times its weight of water, without fuffcring any to drop out. It retains this water more obfliuatcly tlian any of the earths hitherto defcribed. In a freezing cold It contracts more, and parts with more of its water than any other earth ; a circumllaiice which is of fome im- portance in agriculture *. * llij. Alumina has never yet been obtained in a cryftalli- zed form. It has no e(fe(3t whatever on ve£;etable co- lours. The mod intenfe heat does not fufe it, but it has the Angular property of diminillung in bulk in proportion to the intenfity of the fire to which it is expofed. It becomes at the fame time exceedingly hard: Mr Lavoi- fier rendered it capable of cutting glafs ; and Mr Boyle had long before done the fame thing f. f Sbaw't Wedgewood took advantage of this property of alu- ^o;''. '"• mina, and by mean.s of it conllrufted an inllrument for''^"' meafuring high degrees of heat. It confills of pieces ^^'^.,l„J. of clay of a determinate fi/.e, and an apparatus for mea- wood's furing their tulk with accuracy : One of thefe pieces istfie'nionie- put into the fire, and the temperature is eftimated by"*^' the contraftion of the piece. For a more complete de- fcription of this important inftrument, we refer to the article Thermometer in the Encycl. Alumina is hardly lufceptible of combining with ful- phur or phofphorus ; but from the experiments of La Grange, it appears to have an affinity for carbon \. t Nichol- I. The effect of heat on various mixtures of lime and ^f"' J""'- alumina will appear from the following table (J ; li Kir 56. Effca of eat on mixtures of lime and alumina; Propoitions. Htat. Effc-a. 75 Lime 25 Alumina 150'= Wedg. Not melted. 66 Lime 33 Alumina 33 Lime 66 Alumina 150 Remained a powder. {-) Melted. 25 Lime 75 Alumina (x) Melted. 20 Lime 80 Alumina (X) Melted. 226 2. Magnefia and alumina have no aftion whatever on Magnefia each other, aven when expoled to a heat of 150" Wedge- !"id aluini- wood II . _ "^^jj.^j 3. The effeft of heat on different mixtures of barytes ' ' ' ^''' and alumina will appear from the following experiments Barytes and of Mr Kirwarn ^. alumina ; Kk Proportions.^-^*'* (x) Thefe three experiments were made by Ehrman : The heat was produced by direfting a flrcam of oxygen gas on burning charcoal, and is the mod intenfe which it has been hitherto pofFible to produce. 2j8 Alumina. CHEMISTRY. Proportions. Heat. Effs.l. 80 Alumina 20 Barytes i50°Wedg. Scarcely hardened. 75 Alumina 25 Barytes 156 No fign of fufion, a ioofe powder. 66 Alumina 33 Barytes 152 As the former. 50 Alumina 50 Barytes 150 As the former. 20 Alumina 80 Bai7tes 148 Somewhat harder, but no fign of fufion. 25 Alumina 75 Barytes 150 Harder, but no fign of fufion. Part I. Alumina. 4, Nothing is known concerning the efFeft of heat 323 on mixtures of ftrontites and alumina. Alumina 5. Equal parts of alunilna and filica harden in the andfilica; temperature of 160° Wedgewood, but do not fufe *. * ^'"""g' Achard found them infufible in all proportions in a heat '"' '' ^ ' probably little inferior to 150" Wedgewood. Mi.\tures of thefe two earths in various proportions form clays, but thefe are feldom uncontaminated with fome other ingredients. Limefmag- (>• From the experiments of Achard, it appears that nefia/and no mixture of lime, magnefia, and alumina, in which the alumina ; \[^^ predominates, is vitrifiable, except they be nearly in the proportions of three lime, two magnefia, one alu- mina ; that no mixture in which magnefia predominates will melt in a heat below 166' ; that mixtures In which the alumina exceeds are generally fufible, as will appear ^ Ibid. i. 7a. from the following table f . 3 Alumina 2 Lime I Magnefia A porcelain. 3 Alumina 1 Lime 2 Magnefia A porcelain. 3 Alumina I Lime 3 Magnefia Porous porcelain. 3 Alumina 2 Lime 3 Magnefia Porous porcelain. 3 Alumina 2 Lime 2 Magnefia Porcelain. */iiV. j. 73. 431 Magnefia, filica, and alumiua ; f Ibid. i. 73. 131 And lime, magn fia, lilica, and alumina. ^33 Affinities o£ alumina. 7. From the fame experiments, and thofe of Kirwan, 430 ^.Tn'd'^al'u-we'learn, that in mixtures of lime, mina; when the lime .eaCceeds, the mixture is generaUy iulible filica, and alumina, cither into a glafs or a porcelain, according to the pro- portions. The only infufible proportions were, 2 3 Lime 1 I Silica 2 2 Alumina. That If the filica exceeds, the mixture Is frequently fu- fible into an enamel or porcelain, and perhaps a glafs ; and that when the alumina exceeds, a porcelain may often be attained, but not a glafs *. 8. As to the mixtures of magnefia, filica, and alumina, when the magnefia exceeds, no fufion takes place at 150''. When the filica exceeds, a porcelain may often be attained ; and three parts filica, two magnefia, and one alumina, formed a glafs. When the alumina exceeds, nothing more than a porcelain can be produced f. 9. Achard found that equal parts of lime, magnefia, filica, and alumina, melted into a glafs. They fiifed al- fo in various other proportions, efpecially when the fili- ca predominated. The affinities of alumina as as follows : Sulphuric acid, Nitric, ' Muriatic, Oxalic, Arfenic, Fluoric, Sebacic, Tartarous, Succinic, Saccholatlic, Citric, Phofphoric, Formic, Ladllc, Benzoic, Acetous, Boracic, Sulphurous, Nitrous, Carbonic, Pruffic. Sect. VIL Of Jargoma. Among the precious ftones which come from the dij-^q'^™ Ifland of Ceylon, there is one called jargon, which is uf jargoiua* poflelfed of the following properties. Its colour is various, grey, greenilh white, yellowlfh, reddlfh brown, and violet It is often cryftalllzed, ei- ther in right angular quadrangular prifms furmounted with pyramids, or ottahedrals confifling of double qua- drangular pyramids. It has generally a good deal of luftre, at lead internally. It is moftly femitranfparent. Its hardnefs is from 10 to 16 : Its fpecific gravity from 4,416 to 4,7 %. X Ibid. i. It lofes fcarcely any of its weight in a melting heat ;333- for Klaproth found that 300 grains, after remaining in it for an hour and a half, were only one-fourth of a grain lighter than at firft J. Neither was it attacked either { Jour.dt by muriatic or fulphuric acid, even when aflifted by heat, ^hf- 3** At laft, by calcining it with a large quantity of foda, '^ ^"^ he diflblved it in muriatic acid, and found that 100 parts of it contained 31,5 of filica, five of a mixture of nick- el, 434 Part T. Glucina. J. p. 14. 236 Difcovery of giuciiu, C H H M cl and iron, nnd 68 of an cartli potTcffLd of peculiur pro- peities. Tills earth lias been czlhdjtirgonia. Jargonia has a ftrong refcmblancc to ahimlna. It is of a white colour. Its fpeciiic gravity probably exceeds 4,000. It differs from alumina in the compounds which it forms with other bodies, in being inioluble in a boiling lolntion of pure potais or foda, imd in being infulible by heat when mi.xcd with tliele fubftances in a Itatc of dry- » A'lVmin'incfs*. No more of its properties are yet known. S£CT. VIII. Of Glucina. In the beryl was difcovered, fome time ago by Vau- quclin, a new earth, to which he gave the name of g/u- ciiia. To obtain it pure, the beryl, reduced to powder, is to be fuled with thrice its weight of potafs. The mafs is to be diluted with water, diffolved in muriatic acid, and the folution evaporated to drynefs. The re- fiduiim is to be mixed with a large quantity of water, and the whole thrown on a fdter. The fdica, which conftitutes more than half the weight of the (lone, re- mains behind ; while the glucina and the other earths, combined with muriatic acid, remain in folution. They are to be precipitated by means of carbonat ct potafs ; the precipitate is to be wafhed, and then diffolved in ful- phuric acid. When the folution, after potafs has been added to it, has been evaporated to the proper con- fillency, alum cryftals are gradually formed. When as many of thefe have been obtained as poffible, carbonat of ammonia in excefs is to be poured into the liquid, which is firft to be filtered and then boiled for fome time, when a white powder gradually appears. This powder is glucina. It is a foft light powder, without either tafle or fmell, but has the property of adhering ilrongly to the tongue. It has no aftion on vegetable colours, is alto- gether infufible by heat, and neither hardens nor con- trails in its dimenfions. It is infoluble in water, but forms with a fmall quantity of that liquid a palle to a certain degree duftile. It does not combine with oxy- gen, nor with any of the fimple combulUbles ; but ful- phurated hydrogen dilTolves it, and forms with it a hy- drolnlphuret, iimilar in its properties to other hydro- fulphurets. Glucina is foluble in the liquid fixed alka- lies ; infoluble in ammonia, but foluble in carbonat of ammonia. It combines with all the acids, and forms with them fwect tafted falts ; and hence its name, from yhvt.ofyf'weet. Its other properties have not been exa- mined. Sect. IX. Of Tttria and Jgujllna. Difcovery Some time before 1788 was difcovered, in the quar- and ]iro].er ry of Ytterby in Sweden, a peculiar mineral, called ties uf yt- from Profeffor Gadolin, who lirfl analyfed it, gadolinite. ""• Its colour is black, and its frafture like that of glafa. It is magnetic, and foft enough to be fcratched by a knife, and fometimes even by the nail. In this mine- ral a new earth has been difcovered by various chemifts, who have agreed to give it the name oi yttria. When feparated from the other fubflances with which it is I S T R Y. 259 5J7 \Xi 1 lope ties- combined, viz. the oKiden of iron- and mangatiefe, a Y una and little lime, and a conliderable quantity of lilica, it has *^" ''" ,, the appearance of a line while powder, and has neither tafle nor fmell. It is not melted by the application of heat, has no aftion on vegetable blues, and is not fo- luble in water. It is likiwlie inlolnhle In pure alka- lies ; but it dlffolves readily In carbonat of ainmonia. It combines wllh acids, and forms with them falts, which have a fweet talle, and at the fame time a certain de- gree of aullcrity. j.p Trommfdorf has la'ily difcovered in the Saxon icrj'/Uifcovcry a new earth, to which he has ^Iven the name of /Igujli-ol i^u^'iai. tia, becaufe the falts which il forms have little or no tafle. As Trommfdorf's experiments have not hither- to been repeated, the exillence of this earth mufl con- tinue doubtful till the conclufious of the difcoverer be confirmed by other philofophers. These are all the fimple earths that have yet been Rcmarlt ton difcovered; and the firfl four of them have a great ma- the eartlis. ny common properties. They tinge vegetable blues green, they have a ftrong affinity for carbonic acid, and combine readily with all acids. They have fometimes been called alkaline earths. None of the earths have been hitherto decompound- ed, nor has the fmalleft proof ever been brought that they are compounds. We mufl therefore, in the ])re- fent ftate of chemiftry, confider them as fimple bodies. Many attempts, indeed, have been made to fliew that there was but one earth in nature, and that all others were derived from it. The earth generally made choice of as the fimpleft was filica(Y). But none of thefe at- tempts, notwithftanding the ingenuity of feveral of the authors, has been attended with the fmalleft fhadow of fuccefs. We have mentioned formerly, that it was almofl the univerfal opinion of chemifts that metals were compofed of fome of the earths united to phloglfton ; but of late an attempt has been made to prove that all the earths are metallic oxides, and that they can aftually be redu- ced to the ftate of metals. Baron had long ago fufpefted that alumina had fome- what of a metallic nature ; and Bergman had been in- duced, by its great weight and feveral other appearan- ces, to conjefture that barytes was a metallic oxide : But the firft chemlft who ventured to hint that all earths might be metallic oxides was Mr Lavoilier *. * Chemijry, About the year 1790, foon after the publication of MrE;Y''|j ''^' Lavolfier's book, Mr Tondi and Profeffor Ruprecht, both of Schemnitz, announced, thit they had obtained from barytes, by the application of a ftrong heat, a me- tal of the colour of iron, and attiafted by the magnet, which they called borbonium ; from magnefia another, which they called auflrum ; a third from lime, alfo called auflrum ; and a fourth from alumina, which they denominated apulum. Their method of proceeding was to apply a violent heat to the earths, which were fur* rounded with charcoal in a Heffian crucible, and co- vered with calcined bones in powder. But their experiments were foon after repeated by Klaproth, Savorefi, and Tihaulki ; and thefe accurate K k 2 chemifts (y) Mr Sage, however, pitched upon lime. 26o C H E M Caloric, chcmifis foon proved, that the pretended metals were all '"""V—— oi t\xm J>/jcj] r.ure/s of ira:. The iron, by tlie violence of the heat, had been e,\tr.ifted from the crucible, and the phofphorus from the bones. The earths therefore nmft il.U continue a dillinft clafs of bodies: and, as Kla- proth has obferved, their properties are fo exceedingly different from thofe of metallic oxides, that the fuppo- fition of their being compofed of the fame ingredients is coiitraiy to every faft, and to every analogy with which we are acquainted. Cn.4P. V. 0/C.\LORic. Nothing is more familiar to \is than henl ; to at- tempt to define it therefore would be unneceflary . When we fay that n ferjon fteh heat, that ajlone is hot, the ex- prefTions caufe no difficulty ; every one underlf ands them perfcdfly : yet in each of theie propofitions the word heat has a dithnft meaning. In the one, it fignifies the J.-nfaiion of heat ; in the other, the caiife'oi that fenfation, This ambiguity, though of little confcquence in common lii'e, leads unavoidably in philofophical difcuffions to con- fiifion and perplexity. It was to prevent this that the French chemifts made choice of the word caloric to fig- uify the caufe of heat. When I put my hand on a hot itone, I experience a certain fenfation, which I call the 241 fenfation of heat ; the caufe of this fenfation is caloric. Whether Concerning the nature of caloric, there are two opi- ral' nc he a nJons v.hich have divided philofophers ever fince they ^feibftance. t„f„ej their attention to the fubjeft. Some fuppofe that caloric, like gravity, is merely a property of mat- ter, and that it confifts, fome how or other, in a pecu- liar vibration of its particles ; others, on the contrary, think that it is a diftinft fubftance. Each of thefe opi- nions has been fupported by the greateft philofophers ; and the obfcurity of the fubjeft is fuch, that both fides have been able to produce exceedingly plaufible and for- cible arguments. The recent difcoveries, however, in Part I. Caloric. 1 S T R Y. this branch of chtmiftry, have rendered the latter opi- nion much more probable than the former. Indeed we do not fee how it is polIibL' to account for many of the phenomena of nature, unlefs caloric be confidered as a fubftance, as we trull fliall appear from the invettiga- tion into which we are about to enter. We mean, then, with the generality of modern chemifts, to take it for granted that caloric is a fubftance, without pretending to be able to demonftrate the truth of our opinion, but nierely becaufe we conlider it as infinitely more plau- fible than the other. If the receiver of an air-pump, while it contains a thermometer, be fuddenly exhaufttJ of air, the thermometer finks feveral degrees, and then gradually rlfes again to its former height. Now if heat be owing to vibration, how comes it that the fmall quan- tity of matter remaining in the receiver is firft infufB- cient, and afterwards fufficient to maintain the tempe- rature ? Is it not more probable that part of the calo- ric was carried off with the air, and that it gradually returned through tlie glafs, which it is capable of per- vading, though with difficulty *. When air is let into « See Pi:. an exhaufted receiver, the thermometer, as Lambert firft trtfur t: obferved, rifes feveral degrees. Is not this owing to an '^"'< '■"• '' additional quantity of caloric introduced by the air ? The thermometer then finks flowly. Is not this becaufe the fuperabundant caloric gradually pervades the glafs and flies off? Taking it for granted then that caloric is a fubftance, we proceed to examine its propertis. 241 I. When bodies become hot, or, which is the fame Caloric m» thing, when caloric enters into them, they expand in P?"ds bo- every direftion ; and this expanfion is proportional to the accumulation of caloric. The firft: and moil obvious property of caloric then is the power of expanding bo- dies. It does not, however, expand all fubftances equal- ly, and we are ftill ignorant of the law which it follows. All that can be done therefore is to coUeft fails till this law be difcovered. A number of thefe may be feen- in the following Table : i i * BligJcn. •^ [^eijuton. Table of the Expanfion ef various Bodies at different Temperatures . Tem-f e- racure. Water ». Mercury. Linfced Ollf. Alcohol *. Tempe- rature. 100° Water *. Mercury. l.infeed oilf. Alcohol *. 30° ^_ I 00000 100908 100711,8 — 104162 .S2 — 1 00000,0 I 00000 — 105 — 100762,7 35 100000 100030,0 — 100267 no — 100813,6 40 99997 100081,0 — 100539 120 101404 100915,4 45 100005 100131,9 — IO1818 130 — 101017,2 50 100023 100182,8 — IOIIO5 140 — 101119,0 S5 100053 100253,7 — IOI40I 150 102017 101220,8 60 100091 100304,6 — 101688 160 — 101322,6 65 IOOI4I '00355,5 — 101984 167 102753 — 70 100197 100406,4 — IO2281 170 — 101424,4 75 100261 100457,3 — 102583 1 80 — 101526,2 80 100332 100508,2 — 102890 19D 103617 101628,0 85 100411 100559,1 — 103202 200 — 101729,8 90 100694 100610,0 — 103517 103840 212 104577 101835,0 107250 95 100790 100660,9 102560 408 — ■"" II5160 ■\ Newt 9a f Table CHEMISTRY. Tabls of the Expanfton ofvarious Bodies at dijfsrent Temperatures eonliiiueJ. Tempf- Sulph. Nitric Glafs f . Air Oxyxen Azotic Hydrogen Nitrous Cirb. acid Animonia- rature acid ». acid*. gafj. gas 5. gas 5. gas }. ga8§. calgas§. 32° __» lOOCOO lOCOOO I 00000 1 00000 lOOOCO I 00000 100000 1 00000 40 — — — 101790 45 — loooo; — — J-^ 100149 100149 — 104140 5? 10026:? 101C74 100006 — 60 100382 10J389 ___ 106560 65 ioo6n 101767 — — 70 10075 1 102096 — 108950 75 — — ICOOI4 — 77 — — — — 104520 103400 108390 106520 IIIO5O 1279IO 80 — — — III3CO 90 — — — H359O 100 — — 100023 — no _ — II7580 122 — 100033 — 124830 121860 122830 II7630 130660 184870 130 — — — 121870 150 — — 100044 126030 .67 — 100056 — I9OI80 176640 137420* 144370 173850 358780 170 — — 130090 190 — — 100069 133970 2;2 ^"~ 100083 134890 547670^ 694120 139120$ 160290J 200940J 680090I (A) Table of the Expanjion of Metals from 320 to 2i2''f . Tempera- ture. Antimony. Steel. Iron. Caft Iron. Bifmuth. Copper. Caft Brafs. Brafs M^ire. 32° 212 •White! heat 1 20000 I 20 I 30 1 20000 120147 123428* 120000 120151 121500* 120000 122571* 1 20000 120167 120000 120204 120000 120225 IJOOOO 120232 1 Tin. , J ,,. Hammered Lead. Z.nc. ^inc. Zinc S Tin I Lead i Tin I Brafs ^ Ziuc I Pewter. Copper 3 'I in ( B ) I 3^^ 212 120000 120298 120000 12034+ I2COO0 120000 120355 120373 120000 120323 1 20000 ii030i I 20000 120247 120000 120274 I 20000 1 202 1 8 261 Caloric. § Du ftr- Mtibod. art- Air. Phil. Trany xlviii. 612. • Rim Froi: (a) This mark % implies that, owing to fome inaccuracy in making the experiments, the numbers to which it is attached are not to be depended on. (b) The metal whole expanfion is here given was an alloy compofed of three parts of copper and -)ne of tin, . The figures in fome of the preceding columns are to be underftood in the fame manner. Thus in the laft column > but two, the metal coiififted of two parts of brafs alloyed with one of zinc. . • £% -' every direflion, and to continue to ftparate till they are.j..'''7 . oppofed by caloric in other bodies of the fame relativedes of calo. denfity with themfelves, ivhich, by repelling them in itsnc repel turn, compels them to continue where they are. The'-'*''' other. caloric in bodies therefore is in wliat has l)een called by Mr Pidet a ftate of tenfion (c). Its particles are actu- ated by a force which would make them feparate to an indefinite dillance, were they not confined by the op- pofite force of the caloric which lurrounds thci.'. The equililrlam therefore depends on the balancing of two op- pofite forces ; the repulfion between the particles of ca- loric in the body, which tends to diminilh the tenipera- ture ; and the repuliion between the caloric of the body and the furrounding caloric, which tends to raife the temperature. When the firll force is greater than the fecond, as is the cafe when the temperature of a body is higher than that of the furrounding bodies, the caloric flies off, and the body becomes colder. When the lall force is ftronger than the firlt, as is the cafe when a body is colder than thofe which are around it, the par- ticles of its caloric are obliged to approach nearer each other, new caloric enters to occupy the fpace which they had left, and the body becomes hotter. When the two forces are equal, the bodies are faid to be of the fame temperature, and no change takes place *. *See Pic- It is the aftion of thefe oppofite forces which makes'''/"''/'' the thermometer a mcafure of temperature. When ap- ''''"''"• '" plied to any body, it continues to rife or fall till the ca- loric in it and in the body to which it is applied are of the fame tenfion, and then it remains ftationary. The thermometer therefore merely indicates that the tempe- rature of the body to which it is applied is equal to its own. It is obvious that, in order to obtain the real temperature of bodies, the thermometer fliould be fo fmall that the quantity of caloric, which enters or leaves it, may not materially affcft the refult. This property of caloric feems to be the caufe of the elafticity of the gafes, in which, as we fliall fliew after- wards, it exifts in great quantities. Perhaps it is the caufe of elafticitv in general ; for we liave no demon- ftrative evidence that the particles of elaftic bodies repel each other (d), and we are certain that all of them contain caloric. Peihaps alfo it is owing to this repul- five property of caloric that the particles of no body aftually touch each other ; for the lefs caloric we leave in a body, the nearer its particles approach to one ano- ther. The expanfion of bodies by caloric feems alfo to depend on the fame property. The particles of caloric uniting with thofe of the body, endeavour to drag them along when they recede from each other. 1 he expan- fion (b) There was a curious faft concerning dilatation obferved by Mr de Luc. A brafs rod which he ufed as a thermometer became in fummer hahitually longer ; that is to fay, that after being for fome time lengthened by heat, it did not contrad by the application of cold to its old length, but continued fomewhat longer. In winter the contrary phenomenon took place. After being contrafted for fome time by cold, it did not return to its old length on the application of heat, but kept fomewhat fltorter. A leaden rod fliewed tliefe effects in a greater degree. Glafs has not this quality. De Luc fufpefts that this property is inverfely as the elafticity of bodies. Glafs is perfeftly elaftic, and lead is lefs elaftic than brafs. — Journ. de Phyf. xviii. 369. (c) The phrafe was firft ufed by Mr Volta. (d) We acknowledge that feveral philofophers of the firft rank, iEpinus for inftance, and Bofcovich, have fuppofed that the particles of all bodies both attradl and repel each other : but we cannot help thinking it rather improbable (if it be pofTible) that two fuch oppofite properties fhould exift together. 14S Bodies be- come li<;hc- Part I. Caloric, fion of bodies therefore ought to be inverfely as their <| ' ' cohelion, ami diredlly as the tenfion of the caloric which they contain. This property of caloric feems likewile to afford an explanation of a very curious fact, which was firil, we believe, mentioned by De Luc in his Treatile on the Modifications of the Atmofphere, and afterwards afccrtaincd by Dr George Fordyce, that bodies become . abfolutely ligiitcr by bcinir heated. He took a ghfs healed globe three inches in diiii'.eter, with a fliort neck, and weighing 451 grains; poured into it 1700 grains of water from the New river, London, an nearly equal. Platinum,' o J > much inferior to the others. Lead Of rtones and folicli capable of melting. 456 Whether fluids be condu(ftArs of tiluric. 257 •What led him to this opinion. inum,"! ■• water, its fpecific gravity was exaftly equal to that of amber, a fubftance but very little heavier than pure water. A number of fmall pieces of amber were then mixed with this folution, and the whole put into a glafs globe with a long neck, which, on being heated and expofed to cool, exhibited exactly the fame phenomena with the other fluids. A change of temperature, a.-nounting on- ly to a very few degrees, was fufficient to fet the cur- rents a-flowing ; and a motion might at any time be Next to metals ilone feems to be the beft conJiuSors; produced by applying a hot or a cold body to any part but this property varies confiderably in different ftones. of the veflel. When a hot body was applied, that part Bricks are much worfe conductors than moll ftones. of the fluid neareft it afcended; but it defcended on the All lollds capable of being melted become non-conduc- application of a cold body. ,.g tors the moment they are heated to the melting point: If caloric pals through water only by the internal Proofs of the caloric enters them eafily enough, but it remains in motion of its particles, as this experiment feems to'''^"°n; J them_. prove, it is evident that every thing which embarraires*^"'"'" "?» A qnefllon has lately been agitated among philofo- thefe motions niuft retard its tranfmiffion : and accord-jyater I phers, Whether fluids be conduftors of caloric ? No ingly Count Rumford found this to be the cafe. He doubt was entertained of their being not only conduc- took a large lintfeed oil thermometer with a copper tors, but good conduftors, till the publication of Count bulb and glafs tube : the bulb was placed exaftly in the Rumford's Eflays, in which the author contends, with centre of a brafs cylinder, fo that there was a void fpace much plaufibillty of reafoning, that though fluids carry, between them all around 0,25175 of an inch thick. they do not condud heat ; or, in other words, let it pafs The thermometer was kept in its place by means of freely from one particle to another. four wooden pins projefting from the fides and bottom In a fet of experiments on the communication of of the cylinder, and by the tube of it pafling through heat, he made ufe of thermometers of an uncommon the cork flopper of the cylinder. This cylinder was fize. Having expofed one of thefe (the bulb of which filled with pure water, then held in melting fnovv till was near four Inches in diameter) filled with alcohol to the thermometer fell to 32°, and immediately plunged as great a heat as it could fupport, he placed it in a into a veflel of boiling water. The thermometer role window to cool where the fun happened to be flilning. from 32° to zoc in 597 '. It is obvious that all the Some particles of duft had by accident been mixed with caloric which ferved to raife the thermometer mull have the alcohol: thefe being illuminated by the fun, became made its way through the water in the cylinder. The perfeftly vlfible, and dllcovered that the whole liquid in experiment was repeated exaftly in the fame manner; the tube of the thermometer was in a moll rapid mo- but the water in the cylinder, which amounted to 2276 tion, running fwiftly in oppofite direftlons upwards and gr. had 192 gr. of llarch boiled in it, which rendered it downwards at the fame time. The a/cending current much lefs fluid. The thermometer now took 1 109'' to occupied the axis, the defcend'wg cvivrtnv the fides of the rife from 32° to 200°. The fame experiment was again tube. When the fides of the tube were cooled by means repeated with the fame quantity of pure water, having ( F ) When tranfparent, it tranfmits caloric. Vivt I. C H li M ■Caloric. 192 gr. of tifierdown mixed with it, vhich would mcrc- ^•— V— — ly tend to cmbarrafs the motion of the particles, A quantity of Rcwed apples were alfo in another cxjieri. incnt put into the cylinder. The following Tables ex- hibit the refult of all thefe experiments. Time tie Caloric was in pajjing into the Thermometer 159 Tempera- ture. Through the Water and Starch. Thro* the Water and Ei Jerdown. Through llewed Aiiplc'. Through pure Water. Therm, rofc from 3 !" tu 2CG° in seconds. 1109 Seconds. 949 Seconds. IC96J Second-. J97 Therm, rofe 80°, mv.. from So° to 160°, ill 34« 269 335 172 Time the Caloric tuas in paffing out of the Thermometer. Tempera- ture. Througli the Water and Starch. Thro' the Water and Eiderdown. Through ftewed Apples. Through (lire Water. Therm, fell from 200° to 40° in Seconds. 1548 Seconds. 1541 Second?. '7491 Seconds. 1032 Therm, fell 800, viz. from 160° to So=', in 468 460 520 277 Now neither the ftarch nor the eiderdown could pro- duce any alteration in the water except impeding its internal motions; confequently whatever impedes thefe motions diminifhes the condufting power of water. But this could not happen unlefs every individual particle aftually went from the cylinder to the thermometer. Hence it follows that, if liquids be conduiftors, their conducing power is but fmall when compared with their carrying power. All liquids, however, are capable of condufting calo- ric ; for when the fource of heat is applied to their fur- face, the caloric gradually makes its way downwards, and the temperature of every ftratum gradually dimi- nilhes from the furface to the bottom of the liquid. The increafe of temperature in this cafe is not owing to the carrying power of the liquid. By that power caloric may indeed make its way upwards through li- quids, but certainly not downwards. Liquids then are conduftors of caloric. Count Rumford, indeed, has drawn a different con- clufion from his experiments. He fi.\ed a cake of ice in the bottom of a glafs jar, covered one-fourth inch thick with cold water. Over this was poured gently a coniiderable quantity of boiling water. Now if water were a non-con duftor, no caloric could pafs through the cold water, and confequently none of the ice would be melted. The melting of the ice, then, wan to de- termine whether water be a conduftor or not. In two hours about half the ice was melted. This one would think, at firft fight, a decifive proof that water is a con- duftor. But the Count has fallen upon a very ingeni- Suppi.. Vol. I. Part. I. I S T R V, 265 ou6 method of accounting for the melting of the lee, Caloric, without being under the neccflity (as he tells us) of re- • ' nouncing his theory that fluids are non-conduftors. It is well known that the fpecifio gravity of water at 40° is a m:\ximum : if it be cither heated above 40'', or cooled down below 40°, its dcnlity diminifiies. There- fore, whenever a particle of water arrives at the tempe- rature of 40'^ it will link to the bottom of the velTcL Now as the water next the ice was at 32*, it is evident that whenever any part of the hot water was cooled down to 40°, it would fink, difplace the water at 32°, come into contadl with tlie ice, and of courfe melt it. The Count's ingenuity, never without rcfources, ena- bled him to prove completely, that the ice employed in his experiment was adually melted in that manner : for when he covered the ice partially with flips of wood, that part which was (haded by the wood was not melt- ed ; and when he covered the whole of the ice with a thin plate of tin, having a circular hole in the middle, only the part exattly under the hole was melted. From thefe fafts it certainly may be concluded that the ice was melted by defcending currents of water. But the point to be afcertained, is not whether there were defcending currents, but whether water be a con. duftor or not. Now if water be a non.conduftor, by what means was the hot water cooled down to 40°? Not at the furface ; for the Count himfelf tells us, that there the temperature was never under 108'': not by the fides of the velfel ; for the defcending current in one experiment was exadlly in the axis : and it follows ir- refiftibly, from the experiment with the flips of wood, that thefe defcending currents fell equally upon every part of the furface of the ice ; which would have been impoflible if thefe currents had been cooled by the fide of the veflel. The hot water, then, muft have been cooled down to 40° by the cold water below it ; con- fequently it muft have imparted caloric to this cold wa- ter. If fo, one particle of water is capable of abforb- ing caloric from another ; that is, luater is a condudor of caloric. After the hot water has ftood an hour over the ice, its temperature was as follows : At the furface of the ice 40' One inch above the ice 80 Two inches • - 118 Three inches - - 128 Four inches - - 130 Seven inches • - 131 How is it poffible to account for this gradual diminli- tion of heat as we approach the ice, if water be a non- conduftor ? The water, it may be faid, gives out calo- ric at its furface, falls down, and arranges itfelf accord- ing to its fpecific gravity. If fo, how comes it that there is only one degree of difference between the tem- perature at 4 and at 7 inches above the ice ? Thus it appears that the Count's experiment, Inflead of demon- ftrating that water is a non-conduftor, rather favours the common opinion that it is a conduftor. The Count tried whether oil and mercury be con- «^ ' * duftors in the following manner : When water was fro-anj o\\ pro. zen in a glafs jar by means of a freezing mixture. Count ved to be Rumford obferved that the ice firft began to be formed condu<2ort. at the fides, and gradually increafed in thicknefs ; and that the water on the axis of the velTel, which retained its fluidity longeft, being comprefled by the expanfion of the ice, was forced upwards, and when completely L I frozen. 166 C H E M I Caloric, frozen, formed a pointed projeftion or nipple, which ■""v-"^ was foinetimes half an inch higiier than the rt(t of the ice. Upon ice frozen in this manner, he poured olive oil, previuiifly cooled down to 32°, till it flood at the lifiyht of tliree inches above the ice. The veffel was furroiirded as high as the ice with a mixture of pounded ice and water. A folid cylinder of wrought iron, i-Jth inch in diameter, and 12 inches long, provided with a hollow cylindrical fheath of thick paptr, was heated to the temperature of 2 10° in boiling water; and being fuddenly introduced into its fheath, was fuipended from the ceiling of the room, and very gradually let down into the oil, until the middle of the flat furface of the hot iron, which was direCily above the point of conical projtftion of the ice, was diflant from it only t'o'^^^ '^^ an inch. The end of the fneatli dcfcenJed VoVh "' ^n inch lower than the end of the hot nietallic cylinder. Now it is evident, that if olive oil was a condudlor, ca- loric would pafs down through it from the iron and melt the ice. None of the ice, however, was melted ; and when mercury was fubllituted for oil, the refult • Rumjord, was jufl the fame * ; confequently it follows that nei- F.J-iy-n. iJj^T oil nor mercury is a conduftor of heat. But this experiment is by no means fufficiently deli- cate to decide the point. If a thermometer be fubili- tuted inilead of the nipple of ice, it always rites fcve- ral degrees ; whence it follows that, even in this cafe, caloric palTcs downwards; fo that the experiment is in faft favourable to the fuppofition that oil and mer- cury are conduftors. Count Rumford therefore has not proved that fluids are non-conduftors of caloric ; and that they are in truth cunduftors, the author of this article afctrtained in the following manner : The liquid of which the con- ducting power was to be examined was poured into a glals vcfTcl till it filled it about half way ; then a hot liquid ot lels fpeciiic gravity was poured over it. Ther- mometers were placed at the furface, in the centre, and at the bottom of the told liquid ; if thefe rofe, it fol- lowed that the liquid was a condudlor, becaufe the ca- loric made its way downwards. For inflance, to exa- mine the condufting power of mercury, a glafsjar was iialf filled with that liquid metal, and boiling water then poured over it. The thermometer at the furface began immediately to rife, then the thermometer at the centre, and hillly that at the bottom. The firit rofe to 118", the fecond to 90 , and the third to 86": the firfl reach- ed its maximum in i', the fecond in 15', the third in 25'. The conducing power of water was tried in the iame manner with hot oil poured over it ; and the re- iult was fimilar. Fluids, then, as far as experiments have been made, are conduftors of caloric as well as folids ; and hence it follows that caloric is capable of making its way thro' all bodies with which we are acquainted. In this rc- fpedt it differs from all other lubltances, even from light, which, as far as we know, cannot make its way through all bodies. Tranfmif- '-^^^ motion of caloric through bodies is indeed of fioii of c3- two kinds : Through fome it feems to move with the Icric ra- fame rapidity as througli. free fpace ; whillt through diant heat. S T R Y. Part L others, as we' have fecn, it moves flowly. When it Caloric. moves through a body with undiminilhed velocity, it is v ' faid to be tranfmilted through it ; and when its velocity is prodigioufly dlminilhed, it is faid to be conduftcd. Air, and all tranfparent bodies hitherto examined, have the property ot iranfm'tllin^ caluiic through them ; though fome of them, ao glafs, do not tranimit it till after thty have combined with a certain proportion of it : and probably no body tranfnu'ts it unlefs a greater quantity enter than is capable of combining witli it in the flate in which the body is placed. The phenomena of the tranfmifGon of caloric are exaiflly fimilar to the , tranfmlflion of light, and admit of precifely Uie fame ■ explanation. What Scheele and feveral other chemiflij have called radiant heat, is nothing elfe than tranfmitted caloric ; as has been completely proved by Dr Hcr- fchel. See 'TuhRMOMETRtc SpeBrum in this Supplement. t, 6. If equal quantiiiea of water and of mercury be pin- Specific ca- ced at the lame dilfance from a fire, the mercury will loiic of bo- become hot much fooner than the water. After a fuf.'^'^^i "ha:, ficient interval, however, both of them acquire the fame temperature. Now caloric flows into all bodies while they continue of a lower temperature than thofe around them, and it flows with equal rapidity into all bodies of the fame conducting powers, as is the cafe with thcfc two fluids: But if equal quantities of caloric were con- flantly flowiflg into the mercury and the water, and yet the water took a longer time to become hot than the mercury, it mufl require a greater quantity of caloric to raife water to a given temperature than it does to raife mercury. Bodies that require a greater quantity of caloric to raife them to a particular temperature than other bodies require, are faid to have a greater capacity for caloric. That the capacity for caloric i.s different in different bodies, was firfl obferved by Dr Black. Dr Irvine afterwards invefligated the fubjeff, and Dr' Crawford publifhed a great number of experiments on it in his Treatife on Heat. Piofeffor Wilcke of Stock- holm alfo difeovered ths fame property of bodies. He called the quantity of caloric necelTary to raife the tern-- perature of fubllances a given number of degrees, their fpecific caloric ; a term which we fliall alfo employ, be- caufe the phrafe capacity for caloric is liable to a greaf deal of ambiguity, and has introduced confufion into this fubjett (f). It two fubflances of unequal tempe- ratures, as water at 100° and alcohol at 50", be mixed together, the mixture will be of a temperature different' both from that of the water and the alcohol, the water will become colder and the alcohol hotter : the water will give out caloric to the akohol till both are reduced to the fame temperature. Now if it requires juft as much caloric to raife alcohol a certain number of de- grees as it docs to raife water the fame number, that is, if thefe two fluids are of the fame fpecific caloric, it is evident that the temperature of the mixture will be jufl;' 7 i;" ; for as foon as the water has given out 25° of ca- loric, the alcohol has acquired 25°, confequently both will be reduced to the fame temperature, and will re- main flationary ; but if the fpecific caloric of the wa. ter be greater than that ot the alcohol, the tempera, ture of the mixture will be higher than 75° ; for 25" of (f) The term fpecific caloric has been ufed in a different fenfe by Seguin. which a body contains. He ufed it for the ivliole caloric Part I. Calorii _ 16.1 Bxpcri- Iiients on fpecific ca- loric by Wilckc, of caloric in tliat cafe would niifc alcoliol more tlian 2j°. If the fpecific caloric of water be fo much great- er than that of alcohol, that what raifes water 20" will raife alcohol 30" ; then the temperature after mixture will be 80", bccaufe when the water has given out 20\ the alcohol will liave rifen 30% and of courfe both will be of the fame temperature. On the contrary, if the fpecific caloric of alcohol were greater than that of wa- ter, the temperature of the mixture would be under 7 j". If the fame quantity of calorie that raifed alcohol 20" raifed water 30°, then the temperature of the mixture would be 70". Thus the ratios of the fpecific caloric of bodies may be dilcovered by mixing them together at different temperatures. The firil fet of experiments on this fubjcft, in point of time, were probably thofe of Mr VVilcke. They were firft publilhed in the Stockholm TranfaCtions for 1781, but had been made long before. The manner in which they were conduced is exceedingly ingenious, and they furnifh us with the fpecific caloric of many of the metals. The metal on which the experiment was to be made was firft weighed accurately (generally one pound was taken), and then being fufpended by a thread, was plunged into a large veflel of tinplate, filled with boiling water, and kept there till it acquired a cer- tain temperature, which was afcertained by a thermo- meter. Into another fmall box of tinplate exadlly as much water at 32" was put as equalled the weight of the metal. Into this velTel the metal was plunged, and fufpended iri it fo as not to touch its fides or bottom ; and the degree of heat, the moment the metal and wa- ter were reduced to the fame temperature, was marked ■hy a very accurate thermometer. He then calculated what tlie temperature would have been if a quantity of water equal in weigh/ to the metal, and of the fame tem- perature with it, had been added to the ice-cold water inftead of the metal. Let M be a quantity of water at the temperature C, m another quantity at the temperature c, and let their common temperature after mixture be x ; according to a rule demonftrated long ago by Richman, x=;-rT- — ^ ° " ■' M -H m • In the prcfent cafe the quantities of water are equal, therefore M and m are each = i ; C, the temperature r .1 • , J , _ MC -J- ?71 c ot the ice-cold water = 32 : therefore ,.■ ' 32 4-c . M-f-m — J M„..r , ,s the temperature of the metal. CHEMISTRY. ties. Therefore the volume of ice cold water is to a quantity of hot water equal in volume to theme-' as tiie fpecific gravity of the metal to that of the Now Therefore if ^2 be added to the temperature of the me- «al, and the whole be divided by 2, the quotient will ex- prefs the temperature of the mixture, if an equal weitrht of water with the metal, and of the fame temperature with it, had been added to the ice-cold water inftead of the metal. He then calculated what the temperature of the mix- ture would have been, if, inftead of the metal, a quantity of water of the fame temperature with it, and equal to the metal in hulk, had been added to the ice-cold water. As the weights of the ice-cold water and the metal are rqual, their volumes are inverfely as their fpecific gravi- tal, water. Let M = volume of cold water, m = volume ot hot water, g =: fpecific gravity of the metal, i = fpecific gravity of water ; then m : M : : i : g\ hence M . - , "' — ~r — (^ being made 3: i ) — . Subftituting this value of m in the formula, . , . ' ' ■ = x, in v/l -\- m which M : and C = 32, X wi be = . + I (g) We have altered all thefe fonnulas to make them corrtfpond wit'h Fahrenheit's thermometer. They are a pood deal fimpler when the experiments are made with Celfius's thermometer, as Mr Wlleke did. In it the freezing point is zero ; and confequently inftead of 32 in the formula, o is always fubftituted. 267 Calotic. . pi Therefore if the fpecific gravity of the metal be multi- plied by 32, and the temperature of the metal be add- ed, and the fum be divided by the fpecific gravity of the metal -I- r, the quotient will exprefs the tempera- ture to which the ice-cold water would be raifed by adding to it a volume of water equal to that of the me- tal, and of the fame temperature witli it. He then calculated how mucii water at the tempera- ture of the metal it would take to raife the ice-cold wa- ter the fame number of degrees which the metal had raifed it. Let the temperature to which the metal had raifed the ice-cold water be =: N, if in the formula MC-f-mf ~M'+7,r' - "' " '^^ '"^'^^ ~ '^' M = T, C = 32, w N— :!2 will be = ^ j^ . Therefore if from the temperature to which the ice-cold water was raifed by the metal 32 be fubtratled, and if from the temperature of the metal be fubtratled the temperature to which it raifed the wa- ter, and the firft remainder be divided by the laft, the quotient will exprefs the quantity of water of the tempe- rature of the metal which would have raifed the ice-cold water the fame number of degrees that the metal did. XT N-32 Now ^ ^ exprefles the fpecific caloric of the me- tal, that of water being =: i. For (negleding the fmall difference occafioned by the difference of tempera- ture) the weight and volume of the ice-cold water are to the weight and volume of the hot water as i to N— 32 • ^ ^ . and the number of particles of water in each are in the fame proportion. But the metal is equal in weight to the ice-cold water ; It muft therefore contain as many particles of matter ; therefore the quantity of matter in the metal muft be to that in the hot water as N — 32 ^ , I to — _ ^ '. But they give out the fame quantity of caloric ; which, being divided equally among their par. tides, gives to each particle a quantity of caloric in- verfely as the bulks of the metal and water ; that is, the fpecific caloric of the water is to that of the metal as t We fliall now give a fpeclmen or two of I1I3 experi- ments, and the calculations founded on them, as above dcfcribed. I- 1 2 Gold C H E M Gold. Specific Gravity 19,040. 164 Crawfortl, 265 Lavoifier and J.a Place, Temper, to Tempera- Tempe- which it ture to Denomina- would have which it tor of the Num- Tempe- which the me- tal raifoi thewatci been ralfed would have fradion ber of experi- ments. rature of the me- tal. by a (juan- tityof watei equal in weijiht and been railed by water e- qual in bulk and te.iipe- M-3. ' N_32 the numera. heat to the metal. ratureto ihc metal. tor bein^; i . I 163,4" 38.3" 97,7" 38,555" I9.«57 2 •44.5 37.4 88,25 37,58 19,833 3 '27.4 36.5 79,7 36,68 20,500 4 118,4 36,05 75.2 36,15 20,333 5 103,1 2S^(^ 65,75 35>42 18,750 6 95 34.45 63,5 35,06 t9,ooo Mean 19,712 Lead. Specific Gravity 11,^^6. Num- ber of experi- ments. Tempe- rature ol the me- tal- Tempe- rature to vhxh the me- tal raifed thewater at 3J°. Tempera- ture to which the waterwi.'uld have been raifed hy a quantity nf water equal in weight and heat to (he meial. Tempera- ture to which the waterwoulc have been raifed by water equa] in bulk and temijeraturc- to the me- tal. Denomina- tor of the fradlion I c— N N-3» I 186,8 38,3 109,4 44.425 23,571 2 181,40 37,85 106,7 43.473 24,538 3 165,2 37,4 98,6 42,692 23,666 4 5 6 163,4 37.4 97,7 42,548 23,333 136,4 36,5 84,2 40,344 22,200 >3i 36,05 81,5 39,947 24,700 7 '26,5 36,05 79.25 39,585 22,333 ■ 8 107,6 35,15 69,8 3«.339 23,000 9 94,1 34,7 63,05 56,985 22,000 Mtan 23^515 It is needk'fs to add, that the laft column marks^he denominator of the fpecific caloric of the metal, the numerator being always i, and the fpecific caloric of ■water being i. Thus the fpecific caloric of gold is . In exaftlv the fame manner, and by takine: 19,712 ■' ' / o a mean of a number of experiments at different tempe- ratures, did Mr Wilcke afcertain the fpecific caloric of a number of other bodies. He afcertained at the fame timf, that the fpecific caloric of a body did not vary witlr the temperature, but continued always the fame. This will appear evident from the experiments oa gold and lead above exhibited. Next, in point of time, and not inferior in Ingenious contrivances to enfure accuracy, were the experiments of Dr Crawford, made by mi.xing together bodies of different temperatures. Thefe were publifiied in his Trcatife on Heat. Several experiments on the fpecific caloric of bodies were made aifo by Lavoifier and De la Plaee, which, from the well-known accuracy of thefe philofophers, cannot but be very valuable. Their method was exceedingly fimple and ingenious; I S T R Y. it was firft fuggeiled by De la Place. An iiiftrument was contrived, to which Lavoifier gave the name of ca- ' lorimeler. It confills of three circular veflcls nearly in- fcribed into each other, fo as to form three different a- partments, one within the other. Thefe three we fhall call the interior, middle, and external cavities. The in- terior cavity ///y"( fee feftion of the inllrument fig. 4.), into ivhich the fubftances fubmitted to experiment aie put, is compofed of a grating or cage of iron wire, fup- ported by feveral iron bars. Its opening or mouth LM is covered by the lid HG, which is compofed of the fame materials. The middle cavity bbbb is filled with ice. This ice is fupported by the grate m m, and un- der the grate is placed a fieve. The external cavity aaflflis alfo filled with ice. We have mentioned al- ready, that no caloric can pafs through ice. It can en- ter ice, indeed, but it remains in it, and is employed in melting it. The quantity of ice melted, then, is a mea- fure of the caluric which has entered into the ice. The exterior and middle cavities being filled with ice, all the water is allowed to drain away, and the temperature of the interior cavity to come down to 32°. Then the fubftance, the fpecific caloric of which is to be afcer- tained, is heated a certain number of degrees, fuppofe to 2r2', and then put Into the interior cavity enclofed in a thin vefTcl. As it cools, it melts the ice in the mid- dle cavity. In proportion as it melts, the water runs through the grate and fieve, and falls through the co- nical funnel cc d and the tube xy into a veiTel placed below to receive it. The external cavity is filled with ice, in order to prevent the external air from approach- ing the ice in the middle cavity and melting part of it. The water produced from It is carried off through the pipe ST. The external air ought never to be below 32^, nor above 41°. In the firft cafe, the ice in the middle cavity might be cooled too low ; in the laft, a current of air flows through the machine and carries off fome of the caloric. By putting various fubftances at the fame temperature Into this machine, and obfer- vlng how much ice each of them melted in cooling down to 32s it was eafy to afcertain the fpecific calo- ric of each. Thus, if water, in cooling from 212 to 32, melted one pound of ice, and mercury ,029 of r pound ; the fpecific caloric of water was one, and that of mercury ,029. This appears by far the fimpleft method of making experiments on this fubjedl ; and muft alfo be the moft accurate, provided we can be cer- tain that all the melted fnow flows Into the receiver. But from an experiment of Mr Wedgewood, one would- be apt to conclude that this does not happen. He found that the melted Ice, fo far from flowing out, ac- tually yroz^ again, and choaked up the paffage. A table of the fpecific caloric of various bodies was^^j^jjjr^ llkewlfe drawn up by Mr KIrwan, and publlfhed by Ma--n'an. gellan in his Treatife on Heat. , . From all thefe fources we have drawn up the follow. R^fuit of Ing table, which exhibits at one view the fpecific calo- thefe eipe« ric of thofe bodies on which experiments have hkherto'"^""* been made. We have added to it a column, expreffing the fpeci- fic caloric of equal bulks of the fame bodies ; which: feeras to be a more accurate way of confidering this- fubjecl, and indeed the only way in which the phrafe capacity for caloric is intelligible. This column was formed, by multiplying the fpecific caloric of equal weights of the variouj fubftances into their refpeftive fpecific gravities. Table 266 Parti. Caloric. CHEMISTRY. Tasle of the Specific Caloric of Various Bodies, that of Water being a i,oooo (h). Calorie. BoJii I. Gases*. Hydrogen gas - • Oxygen gas ... Common air ... Carbonic acid gas Steam . . - - . Azotic gas - . - II. Liquids. Water Carbonat of ammonia f Arterial blood* - - Cows milk* . . - Sulphuret of ammoniaf Venous blood* . - Solution of brown fugarf Nitric acid J ... Sulphat of magnefia i 7 + Water 8 J ^ Common fait Water 8 Nitre I 7 X Water 8J + Muriat of ammonia Water Tartar I 7 Water 237.3 5 Solution of potafs f Sulphat of iron Water Sulphat of foda Water Oil of olives \ Ammoniaf Muriatic acidf Sulphuric acid Water Alum I 7 Water 4.45 J. Nitric acid 9 Lime Nitre 1 7 . Water 33* Alcohol * - . Sulphuric acid § Nitrous acid-f- Linfeed oilf . . Spermaceti oil * Oil of turpentine f Vinegarf - - ■ Lime 97 + Water 16 J "f Mercury ^ - . Dillilled vinegar f n nia 1 7 X V - .fsf - t - - Specific Gravity. 0,000094 0,0034 0,00122 0,00183 0,00120 r,oooo 1,0324 0,818 1,346 0.9 '53 0,997 1,122 0,8371 840 355 0,9403 0,9910 13.568 Specific Caloric of equal Weighf 21,4000 4.7490 1,7900 1,0459 l,55CO 0,7036 1,0000 1,851 1,030 0,9999 0,9940 0,8928 0,8600 0,844 0,844 0,832 0,8167 0.779 0,765 0,759 0.734 0,728 0,710 0,7080 0,6800 0,6631 0,649 o,6i8i 0,646 0,6021 0,5968 0,576 0,528 0,5000 0,472 0,3870 0.3346 0,3100 0,1030 f equal Volumes. 0,00214 0,00641 I 0,002183 0,00193 0,000952 1,0000 1,03:2 0,8130 I,Z2l6 0,6498 0,7041 0,763 0,4993 1,120 0,780 0,4964 0,4132 0,3966 4.'23 0,1039 Specific Calorie Bodies. Specific of equal of equal Gravity. Weight. Volumes. III. Solids. Icef 0,9000 Ox-hide with the hair * 0,787 Lungs of a rtieep * 0,769 Lean of ox. beef * 0,7400 Rice* 0,5050 Horfe beans * - - 0,5020 Dull of the pine tree * 0,5000 Peafe* 0,4920 Wheat* ■. . . - 0,4770 Barley* .... 0,4210 Oats* ..... 0,4160 Pitcoal* .... 0.2777 Charcoal* . - . . 0,2631 Chalk* .... 0,2564 Ruft of iron * . - 0,2500 White oxide of antimony wafhed • . . - 0,2270 Oxide of copper nearly freed from air * 0,2272 Quicklime {c) - - 0,2199 Stoneware f ... 0,195 Agate **.... 2,648 0,195 0.517 CryftalJ .... 3.189? 0,1929 0,6151 Cinders* .... 0,1923 Swedilh glafs** . . 2,386 0,187 0,448 AHies of cinders * 0,1885 Sulphur f . . . . '.99 0,183 0,3680 Flint glafs t .... 3.3293 0,174 0,5792 Ruft of iron nearly freed from air * . . . 0,1666 White oxide of antimo- ny ditto * . . . o,T 666 Afhcs of the elm * - 0,1402 Oxide of zinc nearly free from air * . • - 0,1369 Iron (.^) .... 7.876 0,1264 0.993 Brars(rt') .... 8,358 0,1141 0,971 Copper (^) ... 8,784 0,1121 1,027 Sheet iron J ... 0,1099 Oxide of lead and tin * 0,102 Gun- metal || - - - 0,1100 White oxide of tin nearly free from air * 0,0990 Zinc (//) .... 7.154 0,0981 0.735 A (lies of charcoal* 0,0909 Silver** .... 10,001 0,082 0,833 Yellow oxide of lead near- ly freed from air * 0,0680 Tin [e) 7.380 o,c66i 0,444 Antimony ( ; but there it ftops. The iee, however, dilTolves flowly ; and at the end of feveral hours, when it ia all jull melted, the thermometer ftill (lands at 32°. Af- ter this it begins to rife, and foon reaches the tempera- ture of the room. Here the ice continues for feveral b.ours colder than the air around it. Caloric muft then be continually flowing into it ; yet it does not become hotter : it is changed, however, into water. Ice, there- fore, is converted into water by a quantity of caloric uniting with it. This calorie has been called /ateni ca- loric, hecaufe its pvefence is not indicated by the ther- mometer. It might, jierhaps with more propriety, as Profeffor Pi&et obfervcs*, be called caloric of f.uidity ; *''^'''' ''■■'■'"' for there are other cafes in which caloric exifts in bo- dies without raifing their temperature. This very im- portant difcovery was made by Dr Black as early as J 757, and feems to have led the way to all the fubfe- quent dii'coveries in this part of chemillry, which have almofl completely changed tlic appearance of the fcience: for the difcovery that caloric may cxift in bodies while the thermometer cannot indicate its prcfence, is one of the ftrongeil links in the chain of fatts by which the uature of cowhullion was afcertained. The caloric which unites with ice, and renders it fluid, appears again during the aft o^ freezing. If a quantity of water be carried into a room where the temperature is below the freezing point, fuppofe at 20°, ic cools gradually down to 32^; but it becomes no colder till it is all frozen, which takes up fome time. The moment it is all converted into ice, it begins .jigain to cool, and foon reaches the temperature of the room. In this cafe, the water is furrounded by a cold atmofphere ; it muft therefore be giving out ca- loric conftantly ; yet it does not become colder till it is all frozen, that is to fay, till it has loll all its ca- loric of fluidity. Dr Black proved, by a very accurate experiment, that the quantity of caloric cf Jluiilily is fufficient to raife the fame quantity of water 140". All foUds become fluid by abforbing a quantity of caloric. Landriani proved that this is the cafe with fTo.vr. A_ fulphur, alum, nitre, and feveral of the metals f ; and /'iv/. xivi. jj. j^^^ \)eQn found to be the cafe with every fubftance hitherto examined. Fluidity, therefore, is owing to a \uiion between the foUd and a certain quantity of ca- loric. The late Dr Irvine of Glafgow advanced a theory on this fubjed different from that of Dr Black. The fpe- clfic caloric of water being greater than that of ice, it requires a greater quantity of caloric to raife it to a given temperature than it does to raife ice. The calo- ric does not therefore become latent ; it only feems to do fo from the greater fpecific caloric of water. This S T R Y. Part r. theory was zcaloufly adopted by Dr Crawford. Dr Caloric. Black obferved very juflly, that it did not account for « the production of fluidity at all. The fpecific caloric of water is indeed greateV than that of ice ; but how is the ice convered into water ? This is an objettion which the advocates for Dr Irvine's, or Dr Crawford's, theory (as it has been improperly called) will not eafdy anfwer. Let us now examine whether tills theory ac- counts for the apparent lofs of caloric. It follows from Mr Kirwan's expcrimenta, that the fpecific caloric of water is to that of ice as 10 to 9(1). Dr Black proved, that as much caloric entered the ice as would have raifed it, had it been water, 140". Let >is fup- pofe that it would only have raifed the ice 140'^; in that cafe the melted ice ought to have been of the tem- perature of 158^, for 10 : 9 : : 140 : 126; but it was only 32°: Therefore 126'^ of caloric have difappear- ed, and cannot be accounted for by the change ot fpe- cific caloric. Nor can the accuracy of Dr Black's ex- periment be fufpefted : it has been repeated in every part of the world, and varied in evei y poflible way. We cannot doubt, therefore, that caloric unites with fubftances, and caufes them to become fluid, or that there is in fad a caloric of Jlutdity dijerent from fpecific caloric. ■ _ _ _ ,jo Water alfo is converted into fleam by uniting wlthcjioric of caloric. Dr Black put an iron veflel, containing fourevaporatiou. ounces of water at tiie temperature of 53 ', upon a call- iron table which was red hot. The water rofe to the boiling point in three minutes ; but it did not after- wards become any hotter. It evaporated, however, in 18 minutes; and the llcam was precifely at the tempe- rature of 212^. During the firft three minutes, it re- ceived 159" of caloric, and as much muft have been en- tering it during every three minutes while the evapo- ration continued, as the temperature was always much lower than that of the table. This caloric, inftead of ralfuig the temperature of the water, was employed in, converting it into fteam. There is alfo, therefore, a quantity of latent caloric in fteam. It might, as Mr Pidlet obfcrves, be called, with propriety, caloric of eva- poration. This caloric appears again if the fteam be condenfed. Ifit be made to pafs, for inftance, through a pipe furrounded with cold water, it is condenfed in the pipe, and drops ont from it in the form of water. The caloric of the fteam enters into the water around the pipe, and the quantity of it in degrees may be dlf- covered by the number of degrees which it raifes that water. By an experiment of this kind, it was proved, that the caloric of evaporation would be fufficient to heat water red hot, were it employed only in raifing its temperature, inftead of converting it into fteam. It is therefore at leaft equal to hoo°. Mr Watt (hewed af- terwards that it was 920°. Even fpontaneous evaporation, as Dr Black firft ob- ferved, is owing to the fame caufe : and this explains why bodies cool when water is evaporated from their furface ; be * Arn di Clint, xi. ">■•:■ (i) We do not know how this was afcertained : Not by mixing water and ice furely ; becaufe that would . taking for granted the thing to be proved ; becaufe it would give a very different refult ; and what is ftill worfe, the fpecific caloric in that cafe would differ according to the temperature and the quantity of water. To give an inftance : Mr Gadolln concludes, from 180 experiments made by mixing hot water and ice, that the fpecific caloric of ice is to that of water only as I to 2 * ; and had he varied the quantities and the temperatures, he might have obtained feveral other ratios. CHEMISTRY. 27» furface ; a faft which has been long known, and which men bepran to think accurately on the fiibjeft, who con- Ca!onc. ^ 'has been employed in warm countries to diminilli the ctived the poffibihty of dcterminii)fj this queftion, was ^^^ temperature of liquids, and even to convert them into Dr Irvine of Glafgow. He invented a theorem, in or- j^^-^,^^-^ ice (k). That water is evaporated by uniting witli ca- der to afcertain the real zero, whicli has, we know not tlicorcin to loric, and not by folution in air, has been proved very for what realbn, been afcribed by feveral writers to Mr Jiftovcr it. completely by De Luc in his Treatife on Meteorology. Kirwan. He took it for granted (and the fad is Jiro- The evaporation of alcohol, ether, and every other ved by all the experiments liitherto made) that the Ipe- fubltance 'on which experiments have been made, has ciiic caloric of bodies continued the fame in evci7 de- been found owing to the fame caufe. Bodies, there- gree of temperature, as long as they remained in the fore, are converted into vapour by uniting with caloric, fame ftate, that is to fay, as long as they continued ei- 8. If caloric, as has been (hewn, exiils in bodies at ther folid or fluid or in a (late of vapour; but that the the lowe ft temperature which we are able to procure, fpecific caloric of the fame body while folid was lefs and if it exifts in them while the thermometer cannot than while fluid, and lefs while fluid than while in a difcover its prcfence— is there any method of afcertain- ilate of vapour. He took it for granted, too, that the ing its abfolute quantity in bodies ? At what degree 140 degrees of caloric which ei.lered ice during its fo- would a thermometer Hand (fuppofmg the thermome- lution without raifing its temperature, entered merely ter capable of meafuring fo low) were tlie body to which In confequence of the increafed fpecitic caloric of the it is applied totally deprived of caloric ? or what degree water, and that they were exaftly proportional to this of the thermometer correfponds to tiie reil zero ? increafed fpecific caloric. He took it for granted, like- The firft perfou (as far as we know), at leaft fince wife, that the fpecific calorie of bodies was proportional to * _^ . ' (k) Galen informs us, that the ancient Egyptians were accuflomed to put water prcvioudy boiled mto earthen jars, and expofe them all night on the upper part of their houfes to the air. Before funrife thefe veffels were put into the ground, moiftened on the outfidc with water, and then furrounded with frelh plants ; by which means the' water was preferved cool during the whole day. Comment, in lib. vi. Hippoc. de morbis vulgar. 4. 10. p. 396. By a fimilar procefs, water, in the Eall Indies, is converted into ice. The following fmgular pafiage, which has been pointed out to us by the ingenious Dr Barclay, Itfturer 011 anatomy in Edinburgh, furnilhes a llriking proof that the ancients were led, by a very different method of- rcafoning, to deduce, from their philofophical theory of the four elements, conclufions concerning the nature of heat not very different from thofe of the moderns. _( " Sic enim res fe habet, ut omnia, quae alantur et qua: crefcant, contineant in fe vim caloris ; fine qua nequt: ali portent nee crefcere. Nam omne, quod eft calidum et igneum, cietur et agitur motu fuo : quod autem alitur 9t crefcit, motu quodam utitur certo et -.equabili ; qui quandiu remanet in nobis, tamdiu ienfus et vita remanet : ■ refrigerato autem et extinfto calore, occidimus ipli et exftinguimur. Quod qnidem Cleanthes his etiain argu- mentis docet, quanta vis infit caloris in omni corpore : negat enim ullum elfe cibum tarn graveni, quiu is node et die concoquatur ; cujus etiam in reliquiis ineft calor his quas natura refpuerit. Jam vero vena; et arteria rni- care non definunt, quafi quodam igneo motu ; animadverfunique faepe eft, cum cor animantis alicnjus evoUura ita niobiliter palpitaret, ut imitarctur igneain celeritatem. Omne igitur quod vivit, five animal five terra editum, id"- vivit propter inclufum in eo calorem. Ex quo intellcgi debet, earn caloris naturam, vim habere in fe vitalem per omnem mundum pcrtinentem. Atque id facillus ccrnemus, toto genere hoc igneo, quod tranat omnia, fubtilius- e-xplicato. ■ Omnes igitur partes mundi (tangam autem maxumas) calore full se fuftinentur. Quod primiim in • terrena natura perfpici poteft. Nam et lupidum conflidlu atque tritu. elici ignem videmus ; et recenti foiujne terram fumare cahnlem ; atque etIam ex puteis jugibus aquam calldam trahi, et id maxume fieri teinporilnis liiberni?, quod magna vis ca-- loris, terra; contineatur cavernis ; eaque hienie fit denfior ; ub eamque cauftam, caloreni infitum in terns cjatinean arftius. ... ■ r- " Longa eft oratio, multa;que rationcs, quibus doceri poffit, omnia, qua; terra conclpiat, fcmina, quxque ipfa ex • fe generala ftirpibus infixa contineat, ea temperatione caloris et oriri et augefcere. Atque aqus eliam admixtu.|i cfle calorem, primum ipfe liquor, tum aqua declarat efFulio : quss neque conglaciaret frigonbus, ncque nive prui- naque concrefceret, nifi eadem fe admixto calore liquefatla et dilapfa difFandeiet. Itaque et aquilonibus i-elKpiif- -_rporibus continget, cum motu atqu . . miiiime eft expers caloris. llle vero et rniilto quldem calore admixtus eft : ipfe enim oritur ex refpiratione aqua- rum : earum enim quali vapor quidam aer hatendus eft. Is autem exiftit motu ejus caloris, qui aqais coutinetur. • Quam fimilitudiiiem cernere poffumus in his aquis, qua; effervefcunt fubditis ignibus. _ Jam_ vera rcl. C H E M ticks of caloric. But this is by no means the cafe : the fpecific gravity of iron, for inflance, is greater than that of tin, yet the fpecilic caloric of iron is more than double that of tin : the fpecific gravity of oxygen gas is greater than that of common air, yet the fpecilic ca- loric of the tird of tlieft fnbftances is more than three times as great as tliat of the other. There mull be fomething, therefore, in bodies themfelvcs quite diffe- rent from, and unconnefted with, the vacuities between their particles, which dilpoies fome to admit more calo- ric than others. And what can that be but a difpofi- tion in diSerent bodies to unite with a greater or a fmallcr quantity of caloric, and to retain it with more or lefs fnmnefs according to their ajfinity for it ? Dr Black pointed out, long ago, by diicovering latent heat, that caloric unites with bodies ; and this feenis to be the only real key for unfolding the aftions of this ex- traordinary fubftance. If caloric be matter, can it be deilitute of that property which all other matter poi- In aftatpoffefles, we mean attraftion? And if it poflcd'es attradllon, chemical rnuft it not combine with thofe bodies that attraft it combina. jyj^ g^ other bodies combine with each other I Mull there not be formed a chemical uin'on between caloric and other fubftances, which can only be broken by che- mical means, by prefenting a third body which has a greater affinity either for the caloric or the body to j,._ which it is united, than they have for each other ? Proved to That it unites chemically with fome bodies, at lead, te the cafe cannot be doubted, as we have flicwn already, that when- in liquids, gy^j. ^ {q\\^ Js converted into a liquid, a quantity of ca- '' loric enters, and remains in it ; and that both the folld and the caloric lofe their charafteriflic properties. This is prccilcly what takes place in every chemical union. All liquids, therefore, confift of folids combined with caloric. We have feen, too, that liquids are converted into vapours by the very fame prucefs. There are there- fore, atlcaft, two very large clafTes of bodies, liquids and vapours, in which we are certain that caloric ex ills in a J73 ilate of chemical combination. Audgtfcs; There is another clafs of bodies which refembles va- pours in almoft all their properties: thefe are the gales. Ijike them, they are invifible and elallic, and capable of indefinite expanfion. Is it not probable, then, that . the gafes alfo, as well as the vapours, owe their proper- tits to caloric ? that they alfo confift of their lefpedtive bafes combined with that fubtlle fubftance i' This pro- bability has been reduced to certainty by an experiment of Lavoilier. By adding two tubes to the calorimeter formerly defcribed, he contrived to make known quan- tities ot air to pafs through the interior cavity, and to fupport combullion. He found, that when a pound of oxygen gas was made to combine in this manner with phofpluirns, as much caloric was difengaged as melted S^-J- pounds of ice*. Now every pound of ice abforbs as much caloric in the aft of melting as is fuf- ficient to raife a pound of water 140". Therefore the whole caloric difengaged was fufficient to raife a pound of water 12250°. AH this could not have come from the phofphorus, becaufe it had been converted into a liquid, and mufl; therefore have abforbed inltead of part- ed with caloric, and becaufe the quantity of caloric dif- engaged in all cafes of combuftion is proportional, not to the combuftible,,but to the oxygen abforbed. Oxy- gen gas, then, is compofcd of oxygen and caloric : and if this be the cafe with one gas, why not with all ? SupPL. Vol. I. Part I. I S T R Y. 273 * Lartrficr. f . i. ch. tj. We may conclude, therefore, that the gafes, as well Ciltxic. as liquids and vapours, owe their form, to the caloric "-"-V"^ which they contain. The only difference between thenx and vapours is, that the latter return to their liquid ftate by the mere aftion of cold ; whereas mofl of the gafes refift the loweft tenqierature which it has been jtofhble to apply. It was natural to expccl, that if ca- loric combined clieinitally with bodies, its af6 lity would be difterent for dillerent fubftances, and that its affinity for fome bodies would be fo great that it would not leave them to combine with any other. It was natural to ex- pcct this, becaufe it is the cafe with every other fubftance with which we are acquainted. The difference, then, between the gafes and vapours is not furprifing. The affinity of the former for caloric is not only much greiit- er than that of the latter, but much greater than that of any other fubftances. It is owing to this flrong affinity between oxygen, And't' be hydrogen, and azot and caloric, that they cannot be the caufe i.f obtained except in a gafeous form : and we (hall dcfcribe 'htir gafc- feveral other fubftances afterwards exaftly in the fame """^ '^'^""' circumllances. Had we any fubftance pofTeftVd of a greater affinity for caloric than they have, we fhould be able, by prefenting it, to deprive them of their gafeous form. Doubtlefs there is a difference in the affinity between thefe bodies themfelves and caloric ; but as all of them are already faturated, this difference cannot be difcovered. If we could obtain them uncombined with caloric, that is to fay, in a concrete ftate, it would be eafy to afcertain this point. Suppofe, for inftance, that hydrogen had the ftrongeft affinity for caloric, and that we poiTeffed it in a concrete Hate — it would be eafy, by prelcntiiig it to the other gafes, to deprive their bafes of the caloric with which they are united, and thus to obtain them alfo uncombined with any other fubftance. But though we are acquainted with no fubftance that Wiiy calo. has a greater affinity for caloric than the bafes of the r.c appeari gafes, there are many fubftances which have a greater '''"■'"& affinity for thefe bales than caloric has. When any ""'^""'°"' fuch fubftance is prefented, the bafe combines with it, and the caloric is left at liberty. Thus, when phofpho- rus is prefented to oxygen gas, the phofphorus and oxy- gen unite together, and the caloric flies off. We are now, therefore, able to anfwer one of the queflions pro- pofed at tlie end of the fecond chapter, Wlience comes the calo;lc which appears during combuftion ? It is fe- parated from the oxygen, which leaves it in order to en- ter into a new combination. o The caloric alfo, which fometimes appears when two .An.1 during bodies combine together, is let at liberty exaftly in the "'^"7 'he- fame manner. When fulphuric acid and water, for in-T'"^*'. '^'""* fiance, are mixed together, a very confiderable heat is "'^"°°'* produced ; a good deal of caloric, therefore, becomes ienfible. In this cafe, the water combines with the acid, and at the fame time lets go the caloric with which it was formerly combined, and becomes dcnfer. In the fame manner, to give another inllance, when water is poured upon quicklime, a very great quantity of caloric becomes manifeft. The water in this cafe combines with the quicklime, and alfumes a concrete form, and of courfe lets go the caloric with which it was previoufly united. „ 10. It is no uncommon thing in nature to obferve Why ccr- two bodies, after combining together, manifefting a '•''■1 mix- much ftronger affinity for a third body than either of '""^^P^"" M m them 74 Caloric. C H E M I tlicni liad while fcparate. Thus, filver has no percep- tible afiiiity for fulphuric acid, ncitlier has iixygeii ; but unite them together, and they combine with that acid vcrv readily. A great many inilances of llie lame kind migiit be produced. Were there fubftances, tlien, which, after combining together, have a greater affinity for caloric than any of tliein had while feparate, this ought not to furprife us, hccaufe the fame phenomenon is often obferved in other bodies. Now this is aftually the cafe with regard to caloric. Mix together, for in- Aance, common fait and fnow, the mixture inftantly be- comes liquid, and fo cold, that it finks the thermometer down to zero. In this cafe, the fnow and fait united have a much ftro?iger affinity for caloric than either of them had while feparate ; they attraft it therefore from other bodies with which they happen to be in conta6t, till they have obtained a dofe fufncient for their fatura- tion ; and thisfaturationthey nianifcit by becoming liquid. It is for this reafon that all falls produce cold during their folution in water, when the freezing point of the folution formed is below that of water. All fuch folutions have a ilrong affinity for caloric ; they therefore attraft it till they are faturated, which appears by their becoming fluid. A number of experiments have been lately made in order to procure artificial cold bv means of fuch cfiinbinations. The moil complete ftt of experiments of that nature with which V!t are acquainted, is thofe of Mr Walker, publifhed in the Philofophical Tranf- aftions for 179;. We rtiall prefent the reiult of his experiments in the following Table : T/iBiE 0/ Freizing Mixtures. S T R Y. Mixtures. Thermometer finlc. Muriat of ammonia 5 parts. Nitre - 5 Water - - 16 From 50° to ]o". Muriat of ammonia 5 Nitre - - 5 Sulphat of foda 8 Water - - 16 From JO to 4. Nitrat of ammonia i Water - - i From 50 to 4. Nitrat of ammonia I Carbonat of foda i Water - - i From 50 to 7. Sulphat of foda 3 Diluted nitric acid 2 From 50 to 3. Sulphat of foda 6 Muriat of ammonia 4 Nitre - - 2 Diluted nitric acid 4 From 50 to 10. Sulphat of foda 6 Nitrat of ammonia 5 Diluted nitric acid 4 From 50 to 14. Phofphat of foda 9 Diluted nitric acid 4 From 50 to 12. Mixtures. Tlierniometcr Onks. Phofphat of foda 9 parts. Nitrat of ammonia 6 Diluted nitric acid 4 From 50° to 21°. Sulphat of foda 8 Muriatic acid - 5 From 50 to 0. Sulphat of foda 5 Diluted fulphuric acid 4 From 50 to 3. Snow - - 1 Common fait - 1 From 32 to c. Snow or pounded ice 2 Common fait - i From to — J. Snow or poimded ice i Common fait - 5 Muriat of ammonia and Nitre - - 5 From — 5 to — 18. Snow or pounded ice 1 2 Common fait - 5 Nitrat of ammonia 5 From — 1 8 to — 25 . Snow and diluted nitric acid From to — 46. Snow - - 2 Diluted fulphuric acid 1 Diluted nitric acid i From — 10 to — 56. Snow - - I Diluted fulphuric acid i From 20 to — 60. Part I. Caloric. In order to produce thefe effefts, the falts employed muil be frefh cryftallized, and newly reduced to a very fine powder. The velfels in which the freezing mix- ture is made fhould be very thin, and juft large enough to hold it, and the materials fhould be mixed together as quickly as poffible. The materials to be employed in order to produce great cold ought to be firft redu- ced to the temperature marked in the table, by placing them in (ome of the other freezing mixtures ; and then tliey are to be mixed together in a fimilar freezing mix- ture. If, for inflance, we wifh to produce a cold =: — 46, the fnow and diluted nitric acid ought to be tooled down to o, by putting the veffel which contains each of them into the 12th freezing mixture in the above table, before they are mixed together. If a flill greater cold is required, the materials to produce it are to be brought to the proper temperature by being pre- viouflv placed in the fecond freezing mixture. This proceis is to be continued till the required degree of cold has been procured *. ^ 7r«...-r 1 1. From the fafts already known, we may conclude,/"/,//, Traiif; that the particles of caloric have two properties, that 1 795- of repelling each other, and of attrafting and being at- ^^^ tradled by other fubftances. As there is no body in„],j^f,(.(,5, nature which does not contain caloric, we may fafely tain mod conclude, that there is no body in nature which has notca'oric. an affinity for it. When it unites with bodies, though the repulfion of its particles may be overcome by their attraction for the particles of the body, and by the at- traftion alltr, Part r. C H E M Caloric, traction of tlielo particles for each other — we cannot '— ■>"— ' fuppofe it anniliilated : It mull; therefore be the more powerful the greater the quantity of caloric combined in any body is. Probably, then, there is mod caloric combined with fjafes, lefs with fluids, and leall with lo- lids. It does not follow, however, from this, that the quantity of caloric combiiied with any body is propor- tional to the diftance between its particles, becaufe that may depend on other caules. Thus, though hydrogen jjas is much rarer than oxygen gas, it does not ioliow that hydrogen is combined with more caloric than oxy- gen, becaufe the rarity may be owing to the fmall- er cohefive force of the particles of hydrogen allow- ing a fmaller quantity of caloric to produce a greater effeft. If caloric unites only chemically with bodies, there ought to be a certain point of faturation between it and CjI" 275 I S T R y. feebler than that between oxygen atid caloric ; for the new compound is eafily broken, and the caloric abfotbed by many other fubllances. We can even conceive this new compound ftill to have an affinity for caloric, to unite with it, and to form another conipotind, the affi- nity between the ingredients of which is ftill feebler. And in this manner may the indefinite iiicreafe of tem- perature be accounted for. Kubftances may be conceived to be condviclors of ca- Caiife'if loric inverfcly as their affinity for it. Good conduftorstli= riifTi- may have very little affinity for caloric ; and for that '''"'.'°"* rcafon it may be eafily hirced through them by the re-p"^^"*' f- pullion of its own particles. But thofe fubllances different which have a great affinity for caloric, combine with it bojie.". the moment it is prefented to them ; and confequently it cannot pafs through them. Thus, when it is pre-, fented to ice, the affinity between the two fubflances is ^%6 the fubftances with which it combines, becaufe this takes fo great, that the caloric unites with the very firft par- place in all other chemical combinations. Oxygen gas, tides of ice which it meets with. The particles behind thefe cannot receive any caloric, except by attrafling it from the particles with which it has already coiiibincd. But the affinity of one particle of ice for caloric cannot be greater than that of another particle of ice: and the union of two bodies cannot be broken by a force not greater than that which unites them ; therefore the ca- loric cannot pafs from one particle to another. Confe- quently, fuppofing all the particles to keep their places, no new caloric could enter. Juft as when a piece of marble is put into fulphuric acid, the crutl of fulphat of lime which very foon covers it prevents the acid from getting to the particles of marble within. But as foon as a particle of ice unites with caloric, water, the new compound, leaves its ftation, and allows the caloric a paffage to the other particles. In the fame manner, wlien caloric 15 prefented to wa- ter, it combines with the outermofl llratum of parti- cles, and forms with them a compound which cannot be decompofed by the other particles of the water, be- caufe their affinity for caloric is no greater than that of the particles already united with it. No more ca- ior inftance, confills of a certain quantity of oxygen united with caloric. Now if this gas be a chtmical compound, the two ingredients ought to faturate each other in fuch a manner, that no more of either could be admitted. But it cannot be denied, that more caloric can ftill be added to oxygen gas, for its temperature may be raifed at pleafure as high as we think proper. This, at firil light, feems to be an infuperable objeftion to the theory, that caloric only combines chemically with bodies. It ought to be remembered, however, that caloric is not fingul^r in this refpeft. There are other bodies in nature, and bodies too which certainly combine with other fubftances only by affinity, which exhibit the very fame phenomenon. Water is capable of combining with fulphuric acid and many other falts almoft in any proportion, at leaft no limits have hither- to been obierved. Oxygen, too, combines with almoft ever)' body in various proportions : We have feen, that with almoft every metal it forms at leall two dift'e- fent oxides. Why then may not caloric be capable of uniting in the fame manner? Allowing, therefore, that it were impoffible to explain v^hy bodies are capable of loric, then, could gain admiffion, were it not that (the combinintr with caloric after faturation, this could be P ... no objeflion to the theory that it only unites ctiemical- iv with bodies, becauie the fame phenomenon is exhi- bited by other bodies which it cannot be doubted com- bine only by means of affinity. The manner in which thefe other combinations are formed has been already hinted, and (hall be conlidered ■inore tnlly afterwards; at prefent we ihall only attempt to explain the aftion of caloric. Let us fuppofe, then, that caloric is prefented to oxygen; that they combine together in a certain proportion, and latiirate each other. The product of this combination is oxygen gas; a fub- ilance polTelTed of properties very different from thofe of caloric or oxygen in a concrete ftate ; it is incapable of being decompoled by any merely mechanical method, and exhibits all the appearances of a firaple fubilance. Let us therefore coniider this compound tor a moment as a fimple fubftance. May it not ftill have an affinity for caloric? and will it not, in that cafe, unite with it ? Oxygen gas and caloric have an affinity for each other; accordingly when prefented to one another they combine in a certain proportion, and form a new cotrpound, differ- ing from oxygen gas, properly fo called, in elafticity, fpecific gravity, and feveral other particulars. The af- iinity, however, between oxygen gas and caloric h mucli fpecific gravity of the new Compound being inferior to that of the uncombined water) it immediately changes its place, and allows another ftratum of particles to oc- cupy its room. Thefe unite with caloric, and are dif- placed in their turn. And in this manner the procefs goes on, till all the particles have combined with calo- ric ; or, which is the fame thing, til! the whole of the water is heated. But fuppofing the firft ftiatnm of particles to remain j, '^^ in their place after their union with caloric, we can pj^^, .i*^^". conceive an affinity ftill to fubfifl between the new com-foliJs. pounil, thus formed, and caloric. In that cafe the new compound, which we fliall call A, would com- bine with an additional dole of caloric, and form a fecond compound B, differing in fcvcral' refpefts from the firft. We can conceive alio the affinity between the firft compound A and caloric to be inferior to that between water and caloric. In that cafe, the fecond ftratum of particles of water would fepurate the addi- tional dofe with which the hrll ftratum had united. In this manner would two flratums of particles combine with caloric. The firft ftratum of particles would com- bine with another dofe of caloric, and form a fecond compound B as before. But this ccnipound could not now be decompofed by the fecond ftratum of particles, M m 3 becaufe C H E M I becaufe they had already uniwd with a dofe of caloric ; and therefore their affinity for a new dofe louU be no greater than that of the firft ftratuni of particles. The procefs of heating could go on no farther. But we can conceive the" fecond compound B, into which the firil ftratum has entered, ilill to have an affinity for ca- loric, to combine with a dofe of it, and to form with it a third compound C. We can conceive, at the fame time, the affinity between the fecond compound B and caloric to be Icfs than that between the firft compound A and caloric. In that cafe, the ftcond ftratum of par- ticles would take thi« lall dofe from the firft ftratum, and form with it a fecond compound B. The third ftratum of panicles, which is ftill uncombined with ca- loric, would now attraft this new dofe from the kcond ftratum, and combine with it. And, fuppofing the ca- loric ftill flowing towards the water, the firft ftratum would again form the third compound C, by uniting with a frefti dofe : this new dofe would be again at- trafted by the fecond ftratum, and the firft ftratum would again form the third compound C, by uniting with another dofe of caloric. Thus three ftratums of particles would be combined witli caloric; the firft ftra- tum would contain three dofes, the fecond ftratum two, nnd the third one. The procefs of heating would again ftop ; becaufe now the affinity of the fecond ftratum is no greater than that of the firft, nor the affinity of the third ftratum greater than that of the fecond, nor that of the fourth than that of the third. But we can con- ceive an affinity ftill to fubfift between caloric and the third compound C, into which the firft ftratum has en- tered, and this affinity, at the fame time weaker than that between the fecond compound B and caloric. In that cafe they would combine and form a fourth com- pound D. This new dofe would be attrafted by the fecond ftratum of particles, which would combine with it and form the third compound C ; the third ftratum would attraft it from the fecond, and form with it the fecond compound B ; and the fourth ftratum would at- traft it from the third, and enter into the firft com- pound A. The firft ftratum would again enter into the fourth compound D ; which would be again de- compofed by the fecond ftratum ; and the compound formed by the fecond ftvatum, by the third ftratum. The fourth compound D would be again formed by the firft ftratum, and again decompofcd by tlie fecond ftratum. It would be formed a third time, and could not now be decompofed. Four ftratums of particles would now have combined with caloric : the firft ftratum with four dofes; the fecond, with three dofes; the third, with two; and the fourth, with one. We can conceive this procefs to go on exaflly in the fame manner, till all the particles of water have combined with a dofe of caloric. In that cafe, the quantity of caloric combined with cverj- ftratum of particles would form a regular decrea- fing feries from that part of the water at which the ca- loric enters to that part which is fartheft diftant from it. The procefs of heating would go on very llowly ; and the heat of that part of the water which is far- theft diftant from the fource of caloric could never be nearly equal to that of the part which is neareft to that fource. This feems in faiSt to be the manner in which all thofe folids are heated which are bad conduftors of caloric : in all probability it is the way in which all fo- lids are heated. S T R Y. Part I. That caloric combines with bodies merely by means Caloric. of affinity, feems at firft fight contrary to fa£l ; for '~~^r~~^ there is no fubftance whatever v/hich may not be cooled go ^j^ji-o^; indefinitely merely by furrounding it with other bodieseaeh other which are colder than itfelf. Place a piece of hot iron,'ecipiucal. for inftance, in cold water, it is very foon cooled down'''' to the temperature of that liquid. This feems plain enough ; the attra£lion of water for caloric is greater tiian that of iron : but reverfe the experiment ; put liot water within cold iron, and the water is cooled in its turn down to the temperature of the iron : fo that the iron alfo has a greater affinity for caloric, as well as the water; which is abfuid. ^Sg But it ought to be remembered, that caloric not on- And why, ly poftcflls affinity, but that it has another property al- fo, of which every other fpecies of matter, except per- haps light, feems to be deftitute, a repulfion between its own particles. It is neceflary for all organifed bodies, and probably for all bodies, that they Ihould poffefs a certain quantity of caloric ; and on this ac- count the greatett care has been taken to fecure its equal diftribution. This feems to be one ufc at leaft of its rcpulfive power ; a power which is never dtftroyed, however clofcly caloric is united with other bodies. We have fhewn already, that this power is increafed by di- minifhing the quantity of furrounding caloric ; and when thus increafed to a certain degree, it may at laft equal, and even exceed, the affinity between the caloric and the bodies to which it is united ; and in that cafe part of the caloric would neceflarily fly off. It feems to be in this manner that bodies reciprocally cool each other, and that they have always a tendency to an equi- librium of temperature. Thus fteam by cold is con- verted into water, and water into ice. And the affini- ty between bodies and that caloric which is employed in regulating the temperature feems to be fo weak, that the repulfion between the particles of caloric eafily over- comes it, and reftores the equilibrium. But the affini- ty between feme fubftances and caloric is fo great, that no diminution of temperature has been found fufficient to overcome it. This is the cafe, as we have already ften, with oxygen gas. The fpecific caloric of bodies feems to depend on Caufe of two things ; their affinity for caloric, and the diftancet' t dific- between their particles. For vi'hat is temperature but "^^"^ '" _^ the dli'pofition of a body to part with caloric? ^^he ^.^Jq^ -^ ^j ' more caloric a body is difpofed to part with, we call itsbodies. temperature the higher ; the lefs it parts with when a colder body is applied, its temperature is laid to be the lower. If oxygen gas parts with no caloric to a ther- mometer which ftands at — io°, we fay its temperature is — 10 ; yet we know that even then it contains, in all probability, much more caloric than the mercury in the thermometer does. Now the rtronger the affinity be- tween any fubftance and caloric, the greater quantity of caloric will be required before the repulfion between its particles is fufficient to overcom.e this attraftion ; confequently the more caloric is neceflary to raife it a given number of degrees. And the farther diftant the particles of bodies are, the farther from one another muft the particles of caloric be to which they are united; and confequently the weaker muft be the repulfion be- tween them. We cannot deny how new this theory of the aftion of caloric will appear to thofe who have been accuftom- ed I 290 Parti. CHEMISTRY. 277 Calor c. ed to look Upon Dr Craw ford's opinions on this fubjed of the oxygen, and, without any of the ufiial phenome- ^ Caloric. ^ ^— ~v— ^ as fully proved ; nor do we pretend that it can be re- na which attend combiiftiow, is converted into phofpho- » coiitiltd with thefe opinions. But this, we hope, is ric acid. StriAly fpeaking, then, combuilion is nothing no proof of its fallehood. We think it can be fairly elfe but the combination of oxygen with the burning ueduced from Dr Black's dodrine of latent heat : we body, and the term might therefore be ufcd in every cafe know, too, that Bergman believed caloric capable of where fuch an union takes place; and in this fenfe indeed ,^4 combining chemically with bodies: and Morveau has it is now cnipluycd by feveral writers. But the term Whether it not only embraced the fame opinion, but feems to af- cumliijllon h in common language confined to t'^"''-' "•^^s^^^''^'^^^^"-^'^ firm, that all the combinations into which caloric en- where the oxygen was previoufly combined with calo- ^^^^g^.^ j, » F.n:\!. ters are chemical *. And were this quellion to be de- ric, and where a quantity of heat and light btcome fen- not ptefent. JMrfio./. cided by authority, we appeal to all the world, whether fible ; and perhaps it would be better, in order to pre- ^'":'!'''' other three men could be produced to whofe decilions vent ambiguity, never to employ it in any other fenfe. 4ff,.iu: ^^^^ ^vould more willingly fubniit { 1 ). We do not, how- We are not yet abfolutely certain that caloric and light ever, mean to reft its evidence on authority ; let it be may not become fenfible in other combinations befides compared with fads, and put to the tell of experiment ; thoi'e into which oxygen enters. There are other fub- and by its correfpondence with theic let it Hand or fall, ftances befides oxygen capable of combining with calo- "^V . 12. Caloric both hallens the folution of falts in wa- ric ; for inftance, hydrogen and azot : and unlcfs their flens'folu!' ter, and increafes the folvent power of the water ; for affinity for caloric be greater than foi; any other fub- tion'and water diifolves a much greater quantity of alnioft every ftance, they may be capable of combining with other ircreafes {alt when hot than when cold. The reafon that calo- fubftances, and Separating from caloric, at leaft the im- the folvent ^.j^ produces thefe effei^is is obvious from thofe proper- poflibilily of this has never yet been demonftrated. It P°*" ties of it which have been defcribed. It hallens folu- is improper, therefore, to appropriate the word comhuf- tion by putting the panicles of the fluid in motion, and t'lon to the combinations of oxygen, till it can be fliewti thus bringing all of them in their turn into contaft with that the phenomena ufually denoted by that name are the fait : for only thofe particles can aCt as folvents never owing to any other caufe. Tliere is even one which are in contad with the fak. It increafes the fol- cafe in which thefe phenomena prefent themfelves, in vent power of the fluid by combining with it, and form- which we are next to certain tliat oxygen has no (liare. ing a compound which has a greater affinity for the fait. There is an affinity between fulphur and iron, and a and which therefore dllTolves more of it than the fluid high temperature promotes their union. When thefe alone woidd have done. This new compound is de- fubllances are mixed together, and heated till they juft ftroyed by cooling ; and then the additional dofe of the begin to appear red hot, they combine together, and fait which had been diflblved is precipitated. at the fame time, as the Dutch cheniifts firlt obferved, 13. We Ihould come now to the confideration of the a good deal of caloric and light is evolved. _ The very tworemainingqueftionspropofed atthcendofthe fecond fame phenomena appear in a vacuum, or in any kind chapter. Why do bodies combine with oxygen at one of air whatever. The explanation of them is very temperature and not at another I And why is caloric fimple and obvious. The fulphur or the iron, or per- necelfary to produce this union ? But as the difficulty haps both, had previoufly been combined with a quan- of thefe queftions is not inferior to their importance, tity of caloric ; and when they united together, this ca- we thall delay any attempt to anfwer them till we come loric of courfe feparated from them. _ jqj 191 to treat of a^wi/^)/. The theory of combuftion adopted by the earlier Stahl's ihe- Metlii>dsof i^.. It now only remains to confider the methods by chemifts was very different from the preceding, '^'^'^j'l' J^^,^i^„'^^y ' obtaining which caloric may be obtained in a fenfible ftate. Thefe as has been already explained, confidered combuftion ^i^^ ^^,^1^^. caloric. methods may be reduced to four; combuftion, percuf- in every inftance as owing to the feparation of phlogil-tion.ifphlo- fion, fridion, and light : the laft of which ftiall be con- ton ; and this opinion foon became univerfal. He con-gidon. fidered afterwards. fidered phlogifton as the fame thing with the element Gornbuf- We have feen already, that the combuftion oi fimple of fire ; which was capable both of becoming fixed in tion en- combujliblcs and mdah \s merely their combination with bodies, and of exifting iii^ a ftate of liberty. Two of plained. oxygen, during which the oxygen parts with the calo- its properties in this lall ftate were heat and light. The ric with which it was formerly united. Now the very heat and the light, then, which became fenfible during fame thing takes place in other combuftions. The com- combuftion, were nothing clle, according to Stahl, but burtible unites with oxygen, which at tiie fame time two properties of phlogifton or the clement ot fire. j^^j gives out its caloric. The change tiien which the Macquer, to whofe illullrious labours feveral of the moft Improved combuftible body fufters is not owing to the adion of important branches of chemiftry owe their exiftence,!'/ Mac- caloric on it, but to its combining with oxygen. The was, we believe, the fii 11 perfon who perceived a ftri-l"'""' very fame change can be brought about without any of king defed in this theory ot Stahl. Sir Ifaac Newton the ufual phenomena which attend combuftion, fimply had proved that light is a body ; it was abfurd, there- by prefenting the oxygen combined with fome other fore, to make it a mere property of phlogifton or the body inftead of caloric. Nitric acid, for inftance, is element of fire. Macquer accordingly confidered phlo- a body v/hich contains in it a good deal of oxygen : gifton as nothing elfe but light fixed in bodies. This If phofphorus be mixed with this acid, it attrads part opinion was embraced by a great number of the moft; diftin- (i) The fame opinion has been embraced by Seguin, Pidet, Gadolin, and feveral other philofophers. We . did not mention them, becaule the theory given above differs in a few particulars from theirs. But we have de- rived much inftrudion from their ingenious writings; and many of the fads which we have given were obtained from them. 278 Cik.tic. 1Q7 SPrieftley, And Craw ford. 399 Jf.irwan's thenry of fhlo^ifton C H E M 1 diftinpjuifhed cliemifts ; and many ingenious arguments were brought forward to prove its truth. But it phlo- giltoM be o;ih' light fixed in bodies, whence coincs the lieat that manitefts itklt during ci)mbullioi\ ? Is this heat merely a property of light ? Dr Black proved that heat is capable of combining witii, or becoming fixed in bodies which are not conibullible, as in ice and water ; and concluded of courfe, that it is not a property but a body. From that time heat or caloric was confidered by the greateft number of chemifts as a iliibinCl Aibftance from phlogillon. Soon after this, a phenomenon, which had been ob- ferved from the earliell ages, and which probably, for that very reafon, had been neglefted, began to be at- tended to ; that combuHibles would not burn except in contact with air. Dr Prieftlev obferved, that the air in which combuftibles had been fuffered to burn till they were extliiguilhed, had midergone a very remarkable change ; for no conibullible would afterwards burn in it, and no annimal could breathe it without fuffo- cation (k). He concluded, as Dr Rutherford had done before him, that this change was owing to phlogif- ton ; that the air had combined with that fubllance ; and that air was neceffary to combullion, by at- trafting the phlogifton, for which it had a ftrong af- finity. If fo, phlogifton could not be light any more than caloric ; for if it feparated from the combuftible merely by combining with air, it could not furely dif- play itfelf in the form of light. The queftion then re- curred with double force, What is phlogifton ? Dr Crawford, of whole ingenious experlmcn'-s on the fpe- cific caloric of bodies we have already given an account, w ithout attempting to anfwer this queftion, made a con- fiderable improvement in the theory of combuftion, by fuppofing that the phlogifton of the combuftible com- bined with the air, and at the fame time feparated the caloric and light with which that fluid had been previ- oufly united. The heat and the light, then, which appeared during combuftion, exifted previoufly in the air. This theory was very different from Stahl's, and certainly a great deal more fatisfadory. But ftill the queftion. What is phlogifton ? remained to be an- fwered. Mr Kirwan, who had already raifed himfelf to the firft rank among chemical phllofophers by many S T R Y. Part I. important difcoveries, and many ingenious Inveftlga- Caloric, tions or iome of the moll difficult parts of chcnn'llry, 't ' attempted to anfwer this queftion, and to prove that phlogifton was the fame with hydrogen*. The fub-* In hN icft was now brought to a ftate capable of the molt /'"'■'' '^ complete decilion. Does hydrogen actually exilt ui all J^ combuftible fubllances ? and is it feparated from, them Refuted, during every combuftion ? The French chemifts who anfwered his treatlfe, (liewed that this is by no means the cale ; and that therefore there was no proof what- ever of the identity of phlogifton and hydrogen. And Mr Kirwan in confequence, with that candour which diftlnguifhes fuperior minds, gave up his opinion as un- tenable. %^t Mr Lavoifier had already put the queftion, What^"''^^"" proof Is there of the exirtence of phlogifton at ^H ■ ton difuri^ There is only this iingle proof, that fubftances after ved. combuftion are different from what they formerly were. That this difference takes place is certainly true ; but it is owing, not to the feparation of any fubftance, but to the combination of one. It follows, therefore, that there is no proof whatever of the exlllence «f any fuch fubllance z% phlug'ijion in nature; and of courfe we muft , conclude that no fuch fubftance exifts (l). 5o» 15. It Is well known that heat Is produced by the P'""'^"^.''"'-, percuflion of hard bodies agalnft each other. When aP Jpre'r. piece of iron is fmartly and quickly ftruck with a ham-jjon mer, it becomes red hot ; and the production of Iparks by the collifion of flint and fteel is too familiar a faft to require being mentioned. No heat, however, has ever been obferved to follow the percuflion of liquids, nor of loft bodies which eafily yield to the ftroke. ,p. It has long been known, that hammering increafes Owing the denfity of metals. The fpeclfio gravity of iron be- Partly to fore hammering is 7,788; after being hammered, 7,840:"'"'™'^" that of platinum before hammering is 19,50; after it, ' 23,00. Now condenfation dimlnifties the fpecific calo- ric of bodies. After one of the clay pieces ufed In Wedgewood's thermometer has been heated to 120°, it is reduced to one half of Its former bulk, though it has loft only two grains of its weight, and Its fpecific calo- ric is at the fame time dlmlnlflied one third f. B ut * ^- ^^''''4''' we cannot conceive the fpecific caloric of a body to be^.'^" V '' dimlnllhed without its giving out at the fame time ajjoz. quantity i (k) Thefe very obfervations had been made almoft a century before by Mayow ; but chemiftry was then in its infancy ; little attention was paid to them, and they had been forgotten. (l) Mr Lavoifier was therefore the author of w-hat Is called ihe aritiphlog'ijlic theory in chemiftry, or the theory ■which accounts for the phenomena of chemiftry without the afliftance of phlogifton. It has been fo caUed iu oppofition to the theory of Stahl, which explained every thin^ by means of phlogiflon, and which is therefore •called the phlog'iflk theory. Some chemift;. have aff^edfed to omit Lavoifier's name altogether, when they fpoke of the antlphlogiftic theory. According to them, that theory was founded upon the experiments and difcoveries of other chemifts, and Lavoi- fier had no other merit but that of brirging it into public notice. That Mr Lavoifier, virtually at leaft, claimed feveral of the difcoveries of others, we are forry to be under the neceflity of acknowledging ; and that many of the experiments, brought forward to difprove the exiftence of phlogifton, were firft made by others, is known to all the world : but It Is equally evident, that the firft perfon who aclually formed the theory was Lavoifier ; and furely the merit lies in that. It is not thofe who coUeft the ftones, and the timber, and the mortar, but he who lays the plan, and ftiews how to put the materials toge- ther, that Is in reality the builder of the houfe. Who did not know, as well as Newton, that a ftone fell to the ground, and that the planets revolved round the fun ? and yet, who but Newton could have formed the theory of gravitation ? We would not be underftood to detraft any thing from the merit of the other illuftrlous phllofo- phers who have adorned the prefent age, liiany of whom are at leaft equal, and fome of them fuperior to Lavoi- fier : But we are afraid that envy, or fome worfe motive, guided the pen of one at leaft of the moft active and vi- lulent antagonlfts of that illuftrlous and unfortunate philofopher. It muft not, however, be concealed, that his t'lieoiy of combuftion is incomplete. See Combustion in this Supplement. Part r. Calo-ic. quantity of caloric ; and we know for certain that ca- *- V loiic is evolved during condtnfation. A ihernionieter plactd within a condenfer riles feveral degrees every »Pir-n.m, time air is thrown in *. We can even fee a reafon for ftil. Tra/j/;this. When the particles of a body are forced nearer J78S. each other, the repulfive power of the caloric combined with them is increafed, and confequently a paitofit will be apt to fly off. Now, alter a bar of iron has been heated by the hammer, it is much harder and brlt- tler than before. It mufl then have become denfer, and confequently mud have j>arted with caloric. It is an additional coniirniation of this, that the fame bar cannot be heated a fecond time by perculTion until it has been expofed for fomc time to a red heat. It is too brittle, and flies to pieces under the hammer. Now lirittlencfs feems in moil cafes owing to the abfence of the ufual quantity of calo'. ic. Glais unannealeil, or, which is the fame thing, that has been cooled very quickly, is always extremely brittle. When glafs is in a ftate of fulion, there is a vaft quantity of caloric accumulated in it, the repulfion between the particles of which mufl of courfe be very great ; fo great indeed, that they would be difpofed to fly off in every direftion with inconcei- vable velocity, were they not confined by an unufually great quantity of caloric in the furrounding bodies : confequently if this furrounding caloric be removed, the caloric of the glafs flies off at once, and more caloric will leave the glafs than otherwife would leave it, bccaufe the velocity of the particles rnnft be greatly increafed. Probably then the brittlenefs of glafs is owing to the deficiency of caloric ; and we can fcarcely doubt that the brittlenefs of iron is owing to the fame caufe, if we recoUeft that it is removed by the application of new caloric. Part therefore of the caloric which appears in confequence of percuffion feems to proceed from the body llruck ; and this is doubtlefs the reafon why thofe bodies, the denfity of which is not increafed bv percuf- fjon, as liquids and foft fubftances, are not heated at all. AncTrarilv ^^ ^^Y /"""' ^'^ '^^^ caloric, becaufe, often at leaft, to combuf- part of it is probably owing to another canfe. By con- tion. denfation, as much caloric is evolved as is fufficient to raife the temperature of fome of the particles of the body high enough to. enable it to combine with the oxygen of the atmofphere. The combination actually takes place, and a great quantity of additional caloric is fcparated by the decompofitlon of the gas. That this happens during the colllfion of flint and fleel cannot be doubted ; for the fparks produced are merely fmall pieces of Iron heated red hot by uniting with oxygen during tlieir paflage through the air, as any one may CHEMISTRY. 279 convince hiinfelf by aflually examining them. Mr Lane Caloric has (hewn that iron pr(jduces no fparks in the vacuum ' " "" '' of an air-pump; but Mr Kirwan has obferved that they are produced under common fpring water ; and we know that iroii at a certain temperature is capable of decom- pofing water. -q. When quartz, rock-cryllal (m), or other very hard''p"k«e. (loneS, are (Iruck agalnll one another they enu't fpark:i. "''"'''"'/ It they be often made to emit fparks above a flieet of 'fJo'','„f„„ white paper, there are found upon it a number of fmallcnfion. black bodies, not very unlike tlie eggs of flies. Thcfe bodies are hard but friable, and wiien rubbed on the paper leave a black Ifain. When viewed with a rai- crofcope, they feem to have been melted. Muriatic acid changes their colour to a green, as it docs that of lavas *. Thefe fubftances evidently produced tlie fparks • Lamanim, by being heated red hot. Lamanon (n) fuppofes that .T"""'"- "'< they are particles of quartz combined witli oxygen. ''^V- 'V^S'- Were that the cafe, the phenomenon would be pre- clfi-ly fimilar to that which is produced by the collifion of flint and ileel. That they are particles of quartz cannot be doubted; but to fuppofe them combined with oxygen is contrary' to all experience : for thefe llone. °' particles moving in ftraight lines from luminous bodies ^ with inconceivable rapidity. The diicovcries of New- ton eftabliflied this opinion on the firm bafis of mathe- matical demonftration ; and fince his time it has been generally embraced. Huyghens, indeed, and Euler, ad- vanced another (o). They confidercd light as a fubtile fluid, filling all fpace, which rendered bodies vifible by its undulations. But they tupported their hypothcfis rather by flarting objcdtions to the theory of Newton, than by bringing forward direct proofs. Their objec- tions, even if valid, infteadof ellablifliing their own opi- nions, would prove only that the phenomena of light are not completely underflood ; a truth which no man will refufe to acknowledge, whatever fide of the quef- tion he adopts, Newton and his difciplcs, on the con- trary, have (hewn that the known phenomena of light are inconjijhnt with the undulations of a fluid, and have brought forward a great number of direft arguments, which it has been impoITible to anfwer, in fupport of their theory. It can hardly be doubted, therefore, that the Newtonian theory of light is the true one, ,jg Dr Bradley, who, by a number of very accurate ex- Vefocity of periments, and a proceis of reatoning peculiarly ingeni.l'ght. ous, 4'feovered the aberration of light of the fixed itars, has fhewn from it that the velocity of light is to that of the earth in its orbit as 10313 to i. Light there- fore moves at the rate of 1952 18 miles in a fecond. ,,. Light, by means of a prilm, may be feparated intoDiviliWe feven rays, differing from each other in colour ; red, """ Icven orange, yellow, green, blue, indigo, violet. None of'^^5'*' thefe are capable of farther decompofition. Marat, in- deed, pretended that he had reduced them to three ; but his experiments are now known to have been mere- ly philofophical frauds, ^15 When light paffes obliquely into a denfer medium, it OiflerinK is refraSed towards the perpendicular; when into a ra-''! fff'^m- rer, from the perpendicular, 6ir Ifaac Newton difco-^' ' ^' vered that the rays differed in their refrangibility in the order in which they have been named, the red being the leaft, the violet the mofl refrangible. Mr Blair has obfervcd, that the ratios of the refrangibility of the different rays, though not their order, vary fomewhat in different mediums *. • FJinhurgh When light paffes. within a certain dillance of a body, P''/. Iran/. N n parallel '"• (o) Dr Franklin did the fame, without taking any notice of thefe philofophere, of whofc opinions perhaps he was ignorant. See Tranf. Philad. III. 5. CHEMISTRY. 319 InflciilioB, defleAion, * rrarJ Light ■which ap- pears du- ring coni- buRioii fup- poled com- bined with oxygen gas 3>4 Difficulties attending this rpi. sion. cated*. In this cafe, it is cviiknt that the light niuft cither combine with the oxygen or the metals. If a quantity of nitric acid he cxpofed for fome time to the lisht, it becomes yellow, as is well known, and a quan- tity of oxygen gas is found floating on its top. If it be now carried to a dark place, the oxygen is gradually abforbed, and the acid becomes coluurlcfs. In this cafe, nitric acid is decompolcd by means of light, and rcfol- ved into nitrous ac'ui and oX) gen gas. The light mult therefore have combined eiliier with the nitrous acid or the oxygen. But no ciiange wliatcver appears to have been produced in the nitrons acid ; for if it be obtained in the dark bv any other proeefs, it has precifely the fame properties. The oxygen, on the contrary, is con- verted into a gas. It is more probable, then, that the llii-ht has combined with the oxygen than with the acid. Hence there is reafon to fufpect that light makes one of the ingredients of oxygen gas. Caloric has already been Ihewn to make another ingredient. During combuftion, a quantity of light as well as ca- loric is almoll always evolved. Wc muil. conclude, there- fore, that light makes a part ot the compolition either of the combullibles themfelves, or of the oxygen gas with which they unite. We have already fliewn that oxvgen gas probably contains light ; and this probabi- lity is confirmed by another faft. Subllances may be combined with oxygen without the emifiion of any light, provided the oxygen be not in the (late of a gas. If phofphorus, for inilance, be put into nitric acid, it attratts oxygen, and is converted into phofphoric acid without the emiiTion of any light. Now if the light which appears during combuftion had been combined with the combullible, it ought to appear in all cafes when that combullible is united with oxygen, whether the oxygen has previoufly been in the ftate of a gas or not. But as this is not the cafe^ we may certainly in- fer, that the light which appears during combuftion is extricated, not from the combullible, but from the oxy- gen gas. And this feems at prefent to be the opinion of the greater number of philofophers. But we muft acknowledge, that this conclufion is not without its difficulties, and difficulties, too, which, in the prefent ftate of chemiftry, it does not feem poffible to furmount. In the firft place, it is evident, that light may be pro- duced during combuftion, though the oxygen be not in the ftate of a gas : For if nitric acid be poured upon oil of turpentine, the oil takes fire, and burns with the greateft rapidity, and a great deal of light is emitted. This combuftion is occafioned by the oxygen of the acid combining with the ingredients of the oil. It fol- lows, therefore, if the light emitted was previoufly com- bined with the oxygen, that oxygen muft contain liglit when not in the ftate of a gas. Mr Prouft has (hewn that a great variety of fimilar combuftions may be pro- duced. But what is very remarkable, by proper cau- tion the very fame combinations may be made to take place without the vifible emifiion of any light. In that cafe they take place very (lowly, as happens alfo when phofphorus decompofes nitric acid ; fo that the emif- iion or non-emilTion of light feems to depend not upon the ftate of the oxygen, fo much as upon the rapidity or llownefs of the combination. It is true, indeed, as the late Dr Hutton of Edinburgh obferved, that light may be emitted in thefe flow combinations though it be not CHEMISTRY. 483 vilible ; and this is very probably the cafe : but then the I.!gl't. proof is deftroycd that light exills in oxygen gas, from its not appearing duting combinations in which the oxygen did not exift previoufly in a gafeous ftate. In the fecond place, the colour of the light emitted during combuftion differs almoft always according to the combullible. During the combuftion of phofpho. rus, tin, and zinc, the liglit emllted is while ; during that of fulphur and bifmuth, blue. Now if this light were united with the oxygen, why does it not appear al- ways (jf the fame colour, whatever be the combuftible? In the laft place, the phenomena of phofpiiori fhcw that light is capable of entering into other bodies as well as oxygen gas ; and the emilfion of light on the colli- (ion of two flint ftcnes, when no oxygen gas can be de- compofed, is a proof of the fame kind, which cannot be got over. In the prefent ftate of chemiftry, therefore, it cannot be concluded, that the light emitted during combuftion does not exift in the combullibles as well as in the oxygen. 3,5 4. Light has the property of heating bodies. All ^'k!>' '''^-3 bodies, however, arc not heated by it. Thofe which '""^"'" arc perfcdly tranfparent, or which allow all the lio-ht to pats throw them, fuifer no alteration in their tem- perature. Thus light may be concentrated upon wa- ter or glafs without producing any effeft. Neither does it produce much change upon thofe bodies (mir- rors for inftance) that refletl all or nearly all the light which falls upon them. And the fmallnefs of the.altcr- ation of temperature is always proportional to the fiiie- nefs of the polilh, or, which is the fame thing, to the quantity of light which is refieftcd. So that we have reafon to conclude, that if a fubftance could be procu- red which refledled all the light that fell upon it, the temperature of fuch a fubftance would not be at all af- fefted by light falling upon it. Dr Franklin expofed upon fuow pieces of cloth of different colours (white, red, blue, blick) to the light of the fun, and found that they funk deeper, and confequently acquired heat, in proportion to the darknefs of their colour. Now it is well known that dark-coloured bodies, even when equally expofed to the light, refleft lefs of it than thofe which are light-coloured. But fince the fame quantity falls upon each, it is evident that dark-coloured bodies muft abforb and retain more of it than thofe which are light-coloured. That fuch an abforption a6lually takes place is evident from the following experiment. Mr Tliomas Wedgewood placed two lumps of luminous or phofphorefcent marble on a piece of iron heated juft under rednefs. One of the lumps of marble which was blackened over gave out no light ; the other gave out a great deal. On being expofed a fecond time in the fame manner, a faint light was feen to proceed from the clean marble, but none at all could be perceived to come from the other. The black was now wiped off, and both the lumps of marble were again placed on the hot iron : The one that had been blackened gave out juft as little light as the other*. In this cafe, the •/■<;/. light which ought to have proceeded from the lumi-rra/i/. 1791 nous marble difappeared : it muft therefore have been ftopped in its paffage out, and retained by the black paint. Now black fubftances are thofe which abforb the moft light, and they are the bodies which are moft heated by expofure to light. Cavallo obferved, that a N n 2 thermometer 284 C H E M l.ght. thentiom«'ter wilh its bulb blackened (lands higher than • one whifh has Its bulb clean, when e^ipofid to the light « Phil. "^ the fun, the light of. day, or the light of a lamp *. TMi/.i7Sc.^Tr Pidlct made the fame oliftrvation ; and took care to afccitain, that when the two tliermomctcrs were allowed to remain hjr fonie time in a dark jdacc, they iic(|uircd preclkly the fame height. He oblerved, too, that when both thermometers had been raifed a certain number of degrees, the clean one fell a good deal fuller than the + Sur Ic oth»-r-[-. Init it is not a fmall degree of heat alone />!/, en. 4. ^lij^-li can be produced by means of light. When its rays are concentrated by a burninj'-glals, they are ca- pable of fetting fire to combuftiblcs with eafe, and even of producii'^' a temperature at leatl as great, if not greater, than what can be procured by the moll violent and bed conducted fires. In order to produce thi<- ef- fe boiling -J 5,6 ° (.Sulphat of potafs 3 point 337 Boiling point of water. 338 Impre^na tt\ with various f.ilts. » Trnr., Berth «7Sj A faturated Xolutioa ;f 10,3 { 5.6 L 0,9 A faturated j f''^\ °^ ^^^^ 7 ^f'.' '^^ f -5' ^ r 1 ■ c ■{ Uoracic acid > boiling -i 2,2 "- folution ot)^, ^ c r 1 \ •.) t Carbonat or ioda J point L'-J) Water. This augmentation varies with the quantity of fait diflolved. In general, it is the greater the nearer the folution approaches to faturation. Class III. Salts •which loiuer the Boiling Point. f In a fraall quantity, lowers the boiling Borax, i. point . . . . (.Saturated folution of, c. 1 , , r r fin a fmall quantity, bulphat ot magneha, < ., . , j /- 1 ^- r '^ ° (Saturated iolution of f A very fmall quantity of. Alum, < A greater quantity, C A faturated folution of. in any proportion. { 1.350' 0,22 2.+7 I.I 0,0 0,7 0,0 2,02 0'45 0,22 1,24 Class IV. VT . r f Small quantity of, lowers the boil- ma, ^ , mg point - - . 0>45 Saturated folution of, raifes do. 9)79 Carbonat f Small quantity of, lowers do. 0,45 of potafs, |_ Saturated folution of, raifes do. 11,2 ,,„ Water was once fuppofed to be incomprefiible, but Water the contrary has been demonftrated by Mr Canton. The f"niprer- Abbe Mongez made a number of experiments, long af- ter that philofopher, on the fame fubjeft, and obtained fimilar refults. ^.g Water was believed by the ancients to be one of the Opinion four elements of which every other body is compofed ; ' -t its and, according to Hippocrates, it was the fubftance"^""^^ which nourifties and lupports plants and animals. That water was an unchangeable element continued to be be- lieved till the time of Van Helmont, who made plants grow for a long time in pure water : From which ek- peviment it was concluded, that water was convertible into all the fubllances found in vegetables. — Mr Boyle having digefted pure water in a glafs veflel hermetically fealed for above a year, obtained a quantity of earthy fcales ; and concluded, in confequence, that he had con- verted it partly into an earth *. He obtained the fame « shaw'i earth by diftilling water in a tall glafs veffel over a Hovie, iii. flow fire f. Margraf repeated the experiment with the 417- fame refult, and accordingly drew the fame conclufion. '' * '" But the opinion of thefe philofophers was never very generally received. The laft perfon who embraced it was probably Mr Wafelton, who publiflied his experi- ments on the fubjcdt in the yournal de Phyjique for 1780. Mr Lavoifier had proved, as early as 1773, *^'''- the glafs veffels in which the diilillation was performed loll a weight exaflly equal to the earth obtained. Hence it follows iirefiftibly, that the appearance of the earth, which was filica, proceeded from the decompofition of the veffels ; for glafs contains a large proportion of fili- ca. It has been fince (hevs'n by Dr Priellley, that wa- ter always decoinpofes glafs when applied to its furface for a long time in a high temperature. Vv'^ ;,. .e formerly mentioned, that water is compofed of oxygen and hydrogen. This great difcovery has con. ■»67' fart II. CHEM Water, contributed more purliaps than any otlier to the advance- '~~"v— ' rnent of the fcience of chemiftry, by fiirniflting a key •tin''' r for the explanation of a uiodi^Yd^"> Total, - Quantity of water obtained. Which is lefs than the gafes confumed by . - . . . 2,832 grains *., ^^^^^ Such are the principal experiments upon which the c/./«i. iiii. opinion is founded tiut water is a compound. Let usJii- examine tliem, and fee wlie'.her they are fufficient to ellablifli that opinion. The circumftances whicli chiefly claim our attention, and which have been chiefly infift- ed on, are thefe : 1. The whole of the gafes was not confumed. Obfcdion? 2. In the refiduum were .''ound feveral fubftancestn the com- which were not introduced, and which mull therefore pcfi""" "f have been formed during the combuftion. water exa. 3. The water obtained was feldom perfeflly pure.*"'"^ It generally contained fome nitric acid. 4. As only part of the gafes were confumed, and as all gafes contain water in them, might not the gas which difappeared have been employed in forming the other fubftances found in the refiduum ? and might not the water obtained have been merely what was former. ly diflolved in the gafes, and which had been precipi- tated during the experiment ? That the whole of the gafes was not confumed will not furprife us, if we recoiled that it is impoffible for that to take place, allowing them to be perfedfly pure, except they be mixed in precifely the proper propor. tions ; and not even then, except every particle oftheui could be raifed to the proper temperature. Nov/ how can this be done in experiments of that nature ? But how is it pofTible to procure a large quantity of gas completely pure ? And fuppofing it were poflible, how can every particle of atmofpiieric air be excluded ? In the laft experiment, notwithilanding every prccau. tion, 15 cubic inches (French) were admitted ; and there is reafon to believe from the refults, that the quan- tity was even confiderably greater than this. But if any atmofpheric air be admitted, there muft be a refi. duum of azotic gas. In the firft experiment, it had been previoufly afcer. tained that the oxygen gas employed contained Ti'h of azotic, or about 233,05 grains ; and the refiduum contained at moft 329,1 grains, or 96,05 grains more than what had for certain pre-exifted in the gafes. In the fecond experiment, the azot in the refiduum amounted at moft to \t]\ of the oxygen gas employed. But the oxygen was procured from the black oxide of manganefe, which always yields a quantity of azot as well as of carbonic acid. It has been afcertained, that the azot, mixed with oxygen gas procured in that man- ner, often exceeds .Jth. Ill tlie third experiment, the azotic gas found in the refiduum amounted to 170,258 grains; and the quanli. ty contained in the gafes before combuftion amounted to 151,178 grains : the furplus, therefore, amounted to 19,0?^ grains. Now, is it not much more probable that thefe incon- fiderablc quantities of azot, which in the laft experi- ment amounted to no more than -j-y-j- part by v/eight of the whole gas employed, pre-exllled in the gafes be- fore the combuftion began, thougii their extreme ml- nutcnefs prevented them from being difcovered, than that they v/ere formed during the experiment : a fup- O o 2 pofition CHEMISTRY. Part IT. • Ann. dd Cbim, iii. 91. \ A'nn. de Cbim. ix. 48. t Phil. "Tranf. 1784. pofitiotl which is direftly contraJifted by a great num. ber of well ulcertained facls. As to the carbonic acid gas, which in the fecond ex- periment amounted to ,V''^ o*" '^e gafcs employed, it was evidently derived from the raauganefe, which al- nioft conrtaiitly contains it. And when carbonic acid is once mixed witli oxygen, it is difficnlt to feparate it by means of lime-water, except a large quantity be ufed, as MrCavendidi Irs well obfervcd. The i-eafon is, that oxygen gas has the property of diffblving carbonic acid, as Mr Welter has remarked *. Mr le Fcvre de Gineau afcertaiucd byexperiment, that 1 8-0 cubic inches of oxy- gen gas, which did not affeft lime-water, loll between y-j-th and ^j'^-th "f 'ts weight when Wiiflied in nnlk of lime (b). In a fecond experiment, he previondy waflied the two gafes in milk of lime, and the refiduum after combuftion contained no carbonic acid gas. In a third experiment he wafiied only the oxygen, and obtained products e- qually free from carbonic acid. It is certain, then, that the carbonic acid is but an accidental mixture. As to the carbonic acid of the third experiment above related, which amounted only to yj-^ P^i't of the gafcs employ- ed, the fource of it has been already pointed out. As to the nitric acid, the quantity of nitre obtained iu Mr Lavoifier's experiment was 56 grains ; which, ac- cording to Mr Kirwan's calculation, contain 30,156 grains of nitric acid ; a quantity coufidcrably lefs than -j-lpth part of the gafes which difappeared. In the fe- cond experiment, the nitre obtained amounted to 80,7 grains ; which, according to Kirwan, contain 43,456 grains of nitric acid, or lefs than jf^rth part of the gafes confumed. Now, as nitric acid is compofed of oxygen and azot, both of which were prefent in the vefTcl, it is eafy to fee how it was produced. And that its pro- duftion is merely accidental, and not neceflary, is evi- dent from the laft experiment, in which no nitric acid was formed. It has been afcertained, indeed, that the formation of this acid during thefe experiments is quite arbitrary. It never is formed when the combultion goes on fo flowly as to produce but little heat, as Se- guin has afcertained f ; becaufe oxygen and azot do not combine except at a high temperature. Nor is it formed even at a high temperature, as Mr Cavendiih has proved :j:, except there be a deficiency of hydrogen; becauie hydrogen has a ftronger affinity for oxygen than azot has. The q_uantity of water obtained in the firft expe- riment was juft ^o grains more than the weight of the gafes whicii had difappeared : the water obtained in the fecond was precifely 30 grains lefs than the gafes confumed : and in the third experiment, the difference was only 16 grains. The quantities of gas operated upon were large ; in all of llie experiments fevcral thou- Water, fand grains, and in one ot them above' 20 thoufand. —— v"— ' Now, how is it poffible that the water produced (liould correfpond fo exadly with the gafes confumed (for the dlfferenccB are fo fmall as not to merit any attention), uiiltfs the water had been formed by the combination of thefe gafes ? Dr PrielUey, however, who made a great many ex- periments on this lubjeft, drew from them a very diffe- rent conclufion ; and thought he had proved, that du- ring the combultion the two gafes combined, and that the combination was nitric acid. This theory was adopt- ed, or rather it was fuggelled, by Mr Keir, who has fuppoited it with a great deal of ingenuity *. * A' ' '• Let us examine thefe experiments of Dr Pricffley f , D/a'w.cv, and fee whether they warrant the conclufions he has art. Kitiy.. drawn from them. The gafes were exploded in velfels'^";'; of copper. He found that the quantity of water ob--j-^^„V tained was always hj's than that of the gafes which hciySS. had ufed. He obtained alfo a confidcrable quantity of nitric acid. In the experiment made on the largeft quantity of the gafes, and from v.-hich he draws his conclufions, the quantity of liquid obtained amounted to 442 grains. This liquid was examined by Mr Keir. It was of a green colour, 72 grains of brown oxide of copper were depofited in it, and it contained a folution of nitrat of copper (copper combined with nitric acid). Mr Keir analyied this liquor : It confilled of pure wa- ter and nitrat of copper ; and Mr Keir concluded that the nitric acii formed amounted to ^^Xh. of the oxygen gas employed. Mr Berthollet, however, has (hewn that it could not have amounted to more than -^-il\\ part J. { Arm da Let us fuppofe, however, that it amounted to ^ gth. A Chim. iiu quantity of oxygen and hydrogen gas has difappeared ; Wliat has become of them ? They have combined, fays Dr Prieftley, and formed nitric acid. This nitric acid is only •j'o'-h "f their weight : Dr Prieftley fuppofes, however, that it contains the whole oxygen and hydro- gen that exifted in thefe gaies, and that all the reft of the weight of thefe gafes was owing to a quantity of water which they had held in folution. Oxygen gas, then (for we {hall negleft the hydrogen, which Dr Prieftley was not able to bring into view at all), is com- pofed of one part of oxygen and 19 of water. Where is the proof of this ? Dr Prieftley informs us, that he afcertained by experiment that half the weight of car- bonic acid gas was pure water. Suppofing the experi- ment accurate (c), what can be concluded from it? Surely to bring it forward in proof, that oxygen gas confiits of 4sth parts, or almoft wholly of water, is downright trifling. It is impoffible, therefore, from Dr Prieftley's experiments, allowing his fuppofitlons and conjedlures their ulmoft. force, to account for the difap- pearing \ (b) I^ime mixed with water till it is of the thicknefs of milk, or rather ai cream. (c) He informs us that the carbonat of barytes does not yield its carbonic acid by means of heat (this Dr Hope has Ihewn to be a miftake) ; but that, when the vapours of water are palled over it, the gas is difengaged: and he determines, by the water miffing, how much has combined with the gas. According to him, 60 grains, of water enter into the compofition of 147 grains of gas. But, befides affigning too fmall a weight to the gas, he forgot that its temperature was high, and that therefore it was capable of combining with much more water than in its ufual ftate : nor did he aicertain whether more of this water was depofited on the veffels ; and yet, by neglefting this precaution, Morveau has Ihewn that Mr Kirwan, in a fimilar experiment, obtained a refult nine times greater than it ought to have been. EncycL Method. Chim. art. Air. Partir. C H E M Water, pcaving of die two gafi'S, or the appearance of tlie \va- '"""*'""' tcr, without admitting that this liquid was adually compoffd of oxygen and hydrogen. H we add to this, that no oxygen gas has hitherto (as far as we know at Icall) been procured abfokitcly free from fome admix- ture of azot, and that his oxygen was always procured lither from red oxide of lead, or from black oxide of manganefe, or red oxide of mercury, all of which fulv llances yield a conlldcrable proportion of azot ; that in one experiment, in which he obferves that his oxygen was very pure, as it had been obtained trom red oxide ot mer- cury, Mr Bcrtiiollet (d) afcerfaincd, by actually making the experiment, that part of the very fatm oxide which Dr Priellley liad employed yielded a gas, -jd of which was azot * ; if we add, that it has been proved beyond the polFibility of doubt, and to Dr Pricl\ley's own fa- tisfavlion, that nitric acid is compofcd cf oxygen and azot — we fliall find it no diflicult matter to explain the origin of that acid in Dr Prieltley's experiments : and if we recolledl that in Seguin's experiment, upon a much larger' fcale indeed than Dr Priefllty's, no nitric acid at all was formed, it will be impoffible for us to believe for a moment that the compound formed by oxygen and hydrogen is nitric acid. Thus Dr Prielt- ley's experiments rather confirm than deftrov the theo- ry of the compofition of water. We obtain from them, however, one curious piece of information, that the pre- fence of copper increafes the quantity of nitric acid formed. This curious fa£l, Vv'itli a variety of others of a fimilar nature, will perhaps afterwards claim our at- tention ; but at prefent we muft confider another theory which this phenomenon fuggeiled, and which was firll propoiVd, we believe, by Mr de la Metherie (e). Had tlie French chemills, it has been faid, employed copper veffels in their experiments, they would have ob- tained three times the quantity of nitric acid. This acid, therefore, mull in their experiments have been de- compofed, after having been formed, for want of a bafe to combine with ; and the azot which appeared in the refiduum was owing to this decompofition. Hydrogen and oxygen, therefore, do not form water, but azot ( f). Let us examine the experiment of Mr Le Fevre by this theory, as the quantity of azot was accurately afcer- tained. The nitric acid obtained amounted to 4:1,456 grains; three times that quantity is 130,^65 grains, into which 230 54 grains of gas were converted ; which is impoffible. Or even fuppofing that the decompofition had been going on during the whole experiment, which is diredlly contrary to Dr PrielUey's experiments, and which there is no reafon whatever to fnppofe, but every reafon againft — ftill the whole azot amounted only to •^th of the quantity of gas employed, allowing this gas I S T R Y. 293 to have contained no azot, which was evidently not the Wattr. cafe. It appears, then, that this hypothefis, even if it ' v '' could be admitted, would be totally inadequate to ac- count h)r the phenomena. liut if we were to examine it by Mr Seguin's experiment, its abfurdity would be Hill more glaring. In that experiment the azotic gas amounted to only 19 grains, and the quantity of gas which difappcared was 5946 grains: fo that were the hypothefis true, oxygen and hydrogen gas would con- fill of one part of oxygen and hydrogen and 312 parts of water ; a fuppofition fo enormoullv abfurd, that it ia impoffible for any perfon even to advance it. It is impofTiblc, therefore, for the pheriomena which attend the combufiion of oxygen and hydrogen gas to be accounted for in any way confillent witli common fenfe, except we fuppofe that water is formed. But the experiments above related, conclufivc as they Dccompo. appear, are not the only ones by which this important fition of f;id has been afcertaincJ. Melfrs Van Trooftwyk and*^'"- Dieman, affifted by Mr Cuthbertfon, filled a fmall glafs tube, -^th ot an inch in diameter and 12 inches long, with diililled water. One end of this tube was fealed hermetically ; but, at the fame time, a fmall gold wire had been pafl'ed through it. Another wire pafl'ed thro' the open end of the tube, and could be fixed at greater or fmalltr dilhmces from the firfl wive. By means of thefe wires, they made a great number of tleftrical ex- plofions pats through the water. Bubbles of air ap- peared at every explofion, and collected at the top of the tube. AVhen eleftric fparks were pafled through this air, it exploded and dif<)ppeared alnioft completely. It mull therefore have confilted of a mixture of oxygen and hydrogen gas, and this gas mull have been formed by the decompofition of the water : for they had taken care to deprive the water before hand of all its air, and they ufed every precaution to prevent the accefs of at- mofpherical air; and, befides, the quantity of gas pro- duced did not diminifh, but rather increafed, by con. tinning to operate a number of times upon the fame water, whicli could not have been the cafe had it been merely air difTolved in water : nor would atmofpherical air have exploded and left only a very fmall refiduum, not more than -g-'o-th part. They had taken care alfo to prove that the eletlric fpark did not contribute to form hydrogen gas ; for on paifing it through fulphu- ric and nitric acids, the produft was not hydrogen, but oxygen gas *. _ « y,„,_ j^ Thefe experiments have been fince repeated by Dr Phyf. xhv. Pearfon, afliftcd by Mr Cuthbertfon. He produced, 3^9- by means of eleftricity, quantities of gas from water, amounting to 56,5488 cubes of ^'sth of an inch each ; on nitrous gas being added to which, it fulfercd a dimi- nution (o) Mr Berthollet had fupplied Dr Priellley with the oxide. He had received two ounces of it from Mr Le Blanc, one of which he fent to Dr Priellley, and the other he referved. (e) Another favourite theory of La Metherie was, that gafes themfelves are dcllitute of gravity, and that they owe their whole weight to the water with which they are combined : that during combuftion the water of the two gafes is depofited ; and that the gafes themfelves efcape through the veflel and are loll. He complains bitterly that this theory had never been noticed by his antagonifts ; as if it were necelTary to refute a hypothefis which is not fupported by any proof whatever, and as if it had not been proved that oxygen increafes the weight of metals, and confequently pofTeires gravity. (f) This, as has been formerly explained, was the original opinion of Dr Priellley ; to which, though he does not explain himfelf fully, he evidently Hill adheres. There is then no difference betweea his theory and this, except what relates to the decoropofition of the nitric acid. 'j'Urnd, i. £94 C H E M I Alcolo!. nution of bulk, nnd nitrous acid sppeaied to have been *■""* formed : It muft therefore liave contained oxygen gas. When oxygen gas was added to the remainder, and an eleftric fpaik paflld through it, a diminution took place pricifely as wlien oxygen and hydrogen gas are mixed : It mull therefore have contained hydrogen. When ai\ eledtric fpark was pafll-d tlirough the gas thus produced from water, the gas difappeared, being no \^''"'"^/''''Aa\\\.\ converted into water*. Such are the proofs by which the compound nature of water is afcertained ; and we do not beheve that any phyfic-al fact whatever can be produced which is fup- ported by more complete evidence. But wliat becomes of the caloric which was previ- oufly combined with thefe gafes ? It pafFes through the vefiel and is loft, and its weight is too inconfiderable to make any fenfible variation in the cjuantity of the pro- diift. If we were to judge from analogy, we would conclude, that the oxygen and hydrogen, while in the flate of gas, are probably fomewhat lighter than after they are condenfed into water ; but the difference, if it exifts, can fcarcely be fenfible. Water is capable of combining with a vaft number of _ . , f'ibltances: all bodies, indeed, which are foluble in wa- waier ^^'^ form a chemical union with it. Its afGnity for other bodies is doubtlefs various, tho' we have no method of afcertaining this difference, ex- cept in thofe bodies which have no affinity, or but a very fmall affinity, for each other ; and it is only in a few even of thefe that this difference can be afcer- tained. If muriat of barytes be poured into lime-wa- ter, the lime is precipitated, owing, no doubt, to the fu- perior affinity of tlie muriat for water. Several very curious inftances of the affinity of different falts for wa- ter have been mentioned by Mr Quatreraere Dijonval. When the folutions of nitrat of lime and nitrat of mag- iiefia in water are mixed together, the nitrat of magne- fia is precipitated. Muriat of magnefia is alfo precipi- tated by muriat of lime, and fulphat of magnefia by fulphat of lime ; fo that it would feem that the falts which have magnefia for their bafis, have a lefs affinity ■; 7«r/rir. ii for water than thofe whofe balls is lime -f. Fhyf.w.i. Water has the property of diffolving oxygen gas. If a quantity of common air be confined for fome time above water, the whole cf the oxygen is abt'orbed, and nothing but the azotic gas remains. This faft was firlt obferved by Mr Scheele. S T R Y. Part If. 34S Combina- tion and 349 CiiAF. II. 0/" Alcohol. "Dilcdve.-y WiNE has been known from the earlieft ages. The of alcohol. Scriptures inform us, that Noah planted a vineyard and drank wine; and the heathen writers are unanimous in afcribing the invention of this liquor to their earlieft kings and heroes. Beer, too, fecms to have been dilco- vered at a very remote period. It was in common ule iLib.ii. in Egypt in the time of Herodotus j. Tacitus informs { d! Afs. us, that it was the drink of the Germans^. Whether rU-.drm'. the ancients had any method of procuring ardent fpirits ch. xxiii. from thefe or any other liquors, does not appear. The Greeks and Romans feem to have been ignorant of ar- dent fpirits altogether, at leafl we can difcover no tra- ces of any fuch liquor in their writings. But among the northern nations of Europe, into.sicating liquors were in ufe from the earlieft ages. Whether thefe li I quors rcfembled the beer of the Germans, we do not Alcohol, know. It is certain, at leaft, that the method of procu- ""^^ ' ring ardent fpirits by dilhllation was known in the dark ages; and it is more tl-.an piobable that it was praftifed in the north of EUrope much earlier. They are mention- ed exjirefsly by 'I hadda^us, Villanovanu's, and LuUy *. ^'f.?- 4''i Ardent fpirits, fuch as brandy, for inftance, rum, and ''',■ whilky, conlift almoft entirely of three ingredients, wa- Method of ter, claJ.'ul or fpir'it of iv'ine, to which they owe tlieirprocuri..g ftrength, and a Imall quantity of a peculiar oil, to which"* they owe their tiavour. 'l"he alcohol may be feparated from the water by the following proccls. Into the whiUcy or other ardent fpi- rit a quantity of potals is to be put, which has jull imme- diately before been expofed for about half an hour in a crucible to a red heat, in order to deprive it of nioifture. Potafs in this ftate has a ftrong attraction for water; it accordingly combines with the water of the fpirit, and the folution of potafs thus formed finks to the bottom of the veffcl, and the alcohol, which is lighter, fwims over it, and may calily be decanted off; or, what is perhaps better, the folution of potals may be drawn off from be- low it by means of a ftop.cock placed at the bottom of the veffcl. It is impoffible to fix the quantity of potafs which ought to be ufcd, becaufe that muft depend en- tirely on the ftrength of the fpirit ; but it is of no con- fequence though the potafs employed be a little more than enough. The alcohol thus obtained contains a little potafs diffolved, wliich may be feparated by dillil- ling it in a water bath with a very fmall heat. The al- cohol paffes over, and leaves the potafs behind. It is proper not to dillil to drynefs. This procefs is firft mentioned by LuUy. Alcohol may be obtained in the fame manner from wine and from beer ; which liquids owe their ilrength entirely to the quantity of that fub- ftance which they contain. _, Alcohol is a tranfpareut liquor, colourlefs like water, it, proper- ^ of a pleafant fmell, and a ftrong penetrating agreeableties. tafte. It is exceedingly fluid, and has never been frozen, though it has been expofed to a cold fo great that the thermomer ftood at — 69'^ -f . \ At V.ud- Its fpecific gravity when pure is about 0,800. />»'' "^'S' It is exceedingly volatile, boiling at the temperature of 176°; in which heat it affumes the form of an elaftic fluid, capable of refilling the preffure of the atmofphere, but which condenfes again into alcohol when that tem- perature is reduced. In a vacuum it boils at 56°, and exhibits the fame phenomena: fo that were it not for the preflure of the atmofphere, alcohol would always exifl in the form of an clallic fluid, as tranfparent and invifible as common air. This fubjeft was firft exa- mined with attention by Mr Lavoifier J. The fadf, J 7""'''- ^ however, had been known long before, rb\J.\^^•■,• Alcohol has a flrong affinity for water, and is mif- cible with it in all proportions. The fpecific gravity of all the different mixtures, in every proportion, and in all the different degrees of temperature, from 32" to lOO", has been lately afcertained with great accuracy by Sir Charles Blagden and Mr Gilpin. But as a very full account of thefe interefting experiments has been given in the Encyclopsedia in the article Spiritdous Liquors, we do not think ourfelves at liberty to repeat it here. If alcohol be fet on fire, it burns all away with a blue flame without leaving any refiduum. Boerhaave obferved, Part II. ,1731 C H E M obfcrved, tlmt when the vapour whicli efcapes during ' this combiillion is collcfted in proper veflcls, it is found to conlllt of nothing but water. Junker had made tlie fame rcmarlc ; and Dr Blacli fufpcfted, from liis own obfcrvations, that tlie quantity of water obtained, if properly collefted, exceeded tlie weight of the alcohol confumed. This obfervation was cim firmed by Lavoifier; who found that the water pruJuccd during the corn- bullion of alcohol exceeded tiie alcohol confumed by about 4th part*. Different opinions were entertained by chemifts about the nature ot alcohol. Stahl thought that it was com- pofed of a very light oil, united by means of an acid to a quantity of water. According to Junker, it was compofcd of phlogifton, combined with water by means of an acid. Cartheufer, on the other hand, affirmed, that it contained no acid, and that it was nothing elfe than pure phlogifton ar\d water. But thefe hypothefes were mere aflertions fupported by no proof whatever. Lavoiller was the firft who attempted to aualyfc it. He fet fire to a quantity of alcohol in clofe vefttls, by means of the following apparatus : BCDE (lig. 6.) is a veflel of marble filled with mercury. A is a ilrong glafs veflel placed over it, filled with common air, and capable of containing about 15 pints (Fiench). Into this vcfTel is put the lamp R filled with alcohol, the weight of which has been exaftly determined. On the wick of the lamp is put a fmall particle of phofphorus. The mercury is drawn up by futtio', to the height IH. This glafs communicates by m.eans of the pipe LK with another glafs veflel S filled with oxygen gas, and placed over a veflel of water T. This communication may be fliut up at picafure by means of the ilop-cock M. Things being thus difpofed, a crooked red-hot iron wire is thruil up through the mercury, and made to touch the phofphorus. This inftantly kindles the wick, and the alcohol burns. As foon as the flame begins to grow dim, the itop-cock is turned, and a communica- tion opened between the veflels S and A ; a quantity of oxygen gas ruflies in, and rtilores the brightncis of the flame. By repeating this occafionally, the alcohol may be kept burning for fume time. It goes out, however, at lart, notwithllandiag the admiflion of oxygen gas. The refuk of this experiment, which Mr Lavoifier repeated a great number of times, was as follows : The quantity of alcohol confumed amounted to 76,7083 grains troy. The oxygen gas confumed amounted to 266,82 cu- bic inches, and weighed 90,^06 grains troy. The whole weight of the fubltances confumed, there- fore, amounted to 167,2143 grains.. After the combuftion, there were found in the glafs veflel 115,41 cubic inches of carbonic acid gas, the weight of which was 78,1 192 grains troy. Tliere was like wife found a confiderable quantity of water in the veffel, but it was not pofllble to collttf and weigh it, Mr Lavoifier, however, ellinnted its weight at 89,095 1 gi'ains ; as he concluded, witii realon, that the whole of the fubilances employed were ftiU in the veflel. Now the whole contents of the veflel coniilled of carbonic acid gas and water; therefore the carbonic acid gas and water together mull be equal to the oxygen gas- and alcohol which had been confumed. But 78,1192 grains of carbonic acid g^s contain,, according to Mr Lavoifier's calculationf , 5 5,279 grain.s of oxygen ; 90,506 grains, however, of oxygen gas had I S T R Y. 295 difappeared ; therefore 35,227 grains mull have been Alcoh.l. em])loyed in forming water. » ' 35,227 grains of oxygen gas require, in order to form water, 6,058 grains of hydrogen gas ; and the quantity of water iormed by this combination is 41,265 grains. But there were found 89,09,- grains of water in the glafs veflel ; therefore 47,83 grains of v/ater mull have exitted ready formed in tlie alcohol. It foUows from all thefe data, that the 76,7083 grains of alcohol, confumed during the combuftion, were com- poltd of 22,840 Carbon, 6,038 Hydrogen, 47,830 Water. 76,7* * ^"'- Such were the confequences which Mr Lavoifier drew " ' from his analyfis. He acknowledged, however, that there were two fources of uncertainty, which rendered his conclufions not altogetlier to be depended upon. The firll was, that he had no method of determining the quantity of alcohol confumed, except by the difference of weight in the lamp before and after combufl;ion ; and that therefore a quantity might have evaporated with- out combuftion, which, however, would be taken into the fum of the alcohol confumed. But this error could not have been great ; for if a confiderable quaiuitv of alcohol had exifted in the ftate of vapour in the veflel, an explofion would certainly have taken place. The other fource of error was, that the quantity of water was not known by aftual weight, but by calculation. 354 To this we may add, that Mr Lavoifier was not war-Ingre.Hipntr ranted to conclude from his experiment, that the water"^^'"^"'' found in the veflel, which had not been formed by the oxygen gas ufed, had exifled in the alcohol in the ftate of water : he was intitled to conclude from his dat.i, that the ingredients of that water exifted in the alcohol be- fore combuftion ; but not that Vtity were aclually com- * bined in the fttte of water, becaufe that combination might have taken place, and in all probability did part- ly take place, during the combuftion. It follows, theie. fore, from Mr Lavoifier's experiments, that alcohol, fuppofing he ufed it perfedlly pure, which is not pre-- bable, is compofed of 0,2988 parts carbon, 0,1840 parts hydrogen,. 0,5 1 7 2 parts oxygen, I,COOO' But it gives us no information whatever of the manner' in which thefe ingredients are combined. That alcohoii contains oxygen, h.is been proved by a very ingenious fet of experiments performed by Mefirs Fourcroy and' Vauquelin. When equal parts of alcohol and fulphnric acid are mixed together, a quantity of caloric in difcn- gagcd, f'lfTicient to elev.ite the temperature of the mix. ture to 190°. Bubbles of air are emitted, the liq'vir be- comes turbid, aifumcs an opal colour, and atthetiid of a few days a deep red. When examined, the fulphuiio acid is found to have fuQ"ered no change ; but the alo- hol is decompofed, partly converted into water and part- ly into ether, a fubftance which we fliall dcfcribc imme- diately. Now, it is evident that the alcohol could not have been converted into water unlefs it had contained oxygen*. * XL-W- When equal parts of fulphuric acid and alcohol are/""''.?"'""- mixed tagether and heat applied, tiie mixture boils at""'"'" ^S**" aoS",. acjG Akohcl, 355 Ether. 3S6 Its proper- tiis. * Count de J^auraguais, 357 Theory of its forma- Cion. C H E M I ZoS", and a liquid <;qual to half the v^;iglit of the alco- hol comes over into the receiver. This liquid is ether. Ether is obfcurely hinted at in feme of the older che- mical authors, but little attention was paid to it till a paper appeared in the Philofop^ieid Tranfaftlons for 173c, written by a German, wiio called himfelf Frobe- Tiius (g), containing a number of experiments on it. In tliis paper it full received the name of et/ier. Ether is limpid and colourlefs, of a very fragrant fmcU, aiid a hot pungent talle. Its fpecific gravity is 0,73911. It is exceedingly volatile, boiling in the open air at 98", and in a vacuum at — 20'. Were it not therefore for the prelTure of the atmofphere, it would always exill in a gafeous ftate. Ether u::ites with wa- ter in the proportion of ten parts of the latter to one of the former". It is exceedingly inflammable, and, when kindled in the Hate of vapour, burns with rapidity, or rather explodes, if it be mixed with oxygen gas. Chemills entertained various opinions refpedling the nature of ether. Macquer fuppofed that it was mere- ly alcohol deprived by tlie acid of all its water. But it was generally believed that the acid entered partly into its compolition. Since the nature uf acids has become better known, a great number of phllofophers have fup- pofed that ether is merely alco'iol combined with a quan- tity of oxygen furniditd by the acid. The real compa- ction of this lingular fub lance has been lately afcertain- ed by the experiments of Fourcroy and Vauquelin. " A combination (fay they) of two parts of fulphu- ric acid and one part of alcohol e'cvates the tempera- ture to 201°, becomes immediate! jyof a deep red co- lour, which changes to black a few days afterwards, and emits a fmell perceptibly ethereal. " V/hen we carefully obferve what happens in the combination of equal parts of alcohol and concentrated iulphuric acid expofed to the action of caloric in a pro- per apparatus, the following phenomena are feen : " I. When the temperature is elevated to 208'^, the fluid boils, and emits a vapour which becomes conden- fed by cold into a colourlels, light, and odorant liquor, ■which from its properties has received the name ot elLer. If the operation be properly condufted, no permanent gas is diiengaged until about half the alcohol has palfed over in the form of ether. Until this period there palfes abfolutely nothing but ether and a finall portion of wa- ter, without mixture of fuiphurous or of carbonic acid. " 2. If the receiver be changed as foon as the fulphu- rous acid manlfefts itfelf, it is obferved that no more ether is formed, but the fweet oil of wine, water, and acetous acid, without the difengagement hitherto of a fino-le bubble of carbonic acid gas. When the fulphu- ric acid contUtutes about four-hiths of the mafs which remai'ns in the retort, an inflammable gas is difengaged, which has the fmell of ether, and burns with a white oily flame. This is what the Dutch chemlfts have call- ed carbonated hydrogen gas, or ohjiant gas, bccaufe when mixed with the oxy-muriatic acid it forir.s oil. At this period the temperature of the fluid contained in the re- tort is elevated to 230^ or 234°. " 3. When the fweet oil of wine ceafes to flow, if the teceiver be again changed, it is found that nothing more pafles but fulphurous acid, water, carbonic acid gas; and that the refiduum in the retort is a black mafs, confifting for the moll part qf fulphuric acid thickened by carbon. S T R Y. Part ir, (g) The name was fuppofed to have been feigned. <' The feries of phenomena here expofed will juftify Alcohol. the following general induiflions: *~~^ "^ " 1. A fmall quantity of ether is formed fpontanc- oufly, and wit limit the alTiftance of heat, by the combi- nation of two parts of concentrated fulphuric acid and one part of alcohol. " 2. As foon as ether is formed, there is a produc- tion of water at the fame time ; and while the firll: of thefe compolitions takes place, the fulphuric acid under- goes no change in its intimate nature. " 3. As foon as the fulphurous acid appears, no more ether is formed, or at lealt very little ; but then there pafles the fweet oil of wine, together wiili water and acetous acid. " 4. The fweet oil of wine having ceafed to come over, nothing further is obtained but the fulphurous and carbonic acids, and at lail fulphur, if the dillillation be carried to drynefs. . " The operation of ether is therefore naturally divi- ded into three periods : the firtt, in which 3 fmall quan- titv of ether and water are formed witliout the aflTiftance of heat ; the fecond, in which the whole of the etlier which can be obtained is difengaged witliout the ac- companiment of fulphurous acid; and the third, in which tlie fweet oil of wine, the acetous acid, the fulphurous acid, and the carbonic acid, are afforded. The three ilages have no circumflance common to all, but the con- tinual formation of water, which takes place during the whole of the operation. " The ether which is formed without the afliftanceof caloric, and the carbon which is feparated without de- rompofition of the fuljihuric acid, prove that this acid acts on alcohol in a manner totally diflercnt from what has hitherto been fuppofed. It cannot, in fa£t, be af- firmed, that the acid is altered by the carbon, becaule dally experience ftiews that no fenfible attraction takes place between thefe two bodies in the cold ; neither can it be afFefled by the hydrogen ; for in that cafe fulphu- rous acid would have been formed, of which it is known that no,trace is exhibited during this firft period. We mule therefore have recourfe to another fpecies of ac- tion, namely, the powerful attraftion exercifed bytjie ful- m phuric acid upon v/ater. It is this which determines the " union of the principles which exifl: in the alcohol, and with which tlie concentrated acid is In contaft : but this aftion is very limited if the acid be fmall in quantity ; for an equation of affinity is foon eftabliflied, the effett ^ of which is to maintain the mixture in a flate of repole. ■ " Since it is proved that ether is formed in the cold by the mixture of any quantities of alcohol and fulphu- ric acid, it is evident that a mafs of alcohol might hi completely changed into ether and vegetable acid by ufing a fufficient abundance of fulphuric acid. It is equally evident that the fulphuric acid would not by this means undergo any other change than that of being diluted with a certain quantity of water. This obler- vation proves that alcohol contains oxygen, becaule wa- ter cannot exift without this principle, which muft be afforded by the alcohol only, lince the fulphuric acid fuffers no decompofition. " We mull not, however, imagine, from thefe fafls, that ether is alcohol minus oxygen and hydrogen. Its properties alone would contradidl this ; for a quantity of carbon proportionally greater than that of the hy- drogen Part ir. C H E M Alcnhol. drogen 18 at the fame time feparated. It may, in faft, ' V ' ' be conceived that the oxygen, whicl- iii tliis cafe com- bines with the liydrogeii to form water, not only fatu- rated that liydrogen in the alcohol, but h'kewiie the carbon. So that, inftead of confidering ether as alcoliol minns hydrogen and oxygen, we mu(t, by keeping an account of the precipitated carbon and the fniall quan- tity of hydrogen contained iji the water which is form- ed, regard it as alcohol plus hydrogen and oxygen. " The foregoing are the efFeils produced by a combi- nation of alcohol and fulphuric acid, fpontaneouily pro- duced without foreign heat. Let us, in the next place, obferve how this combination is effeftcd when caloric is added. The phenomena are then very different, tho' feme of the refults are the fame. " In the firll place, we muit obferve, that a combina- tion of fulphuric acid and alcohol in equal ]»arts does not boil at lefs than 207 degrees of temperature, while (hat of alcohol alone bolls at 176. Now fince ebullition does not take place till the higher temperature, it is clear that the alcohol is retained by the affinity of the ful- phuric acid, which hxes it more confidcrably. Let us alfo confider that organic bodies, or their immediate pro- dufts, expofed to a lively brifk heat, without the poffi- bility of efcaping fpeedily enough from its aftion, fuifer B partial or total decompofition, according to the degree of temperature. Alcohol undergoes this lalt alteration when paflTcd through an ignited tube of porcelain. By this fudden decompofition it is converted into water, carbonic acid, and carbon. The reafon, therefore, why alcohol is not decompofed when it is fubmittcd alone to iieat in the ordinary apparatus for diflillation, is, that - the temperature at which it rifes in vapours is not ca- pable of effefting the fcparation of its principles ; but when it is fixed by the fulphuric acid or any other bo- dy, the elevated temperature it undergoes, without the poflibility of difengagement from its combination, is fuf- Hcient to effect a commencement of decompofition, in which ether and water are formed, and carbon is depo- fited. Nothing more therefore happens to the alcohol in thefe circumftances than what takes place in the dif- tillation of every other vegetable matter in which water, oil, acid, and coal, are afforded. " Hence it may be conceived that the nature of the produfts of the decompofition of alcohol muft vary ac- cording to the different degrees of heat ; and this ex- plains why at a certain period no more ether is formed but the fweet oil of wine and acetous acid. In faft, ■when the greateft quantity of the alcohol has been chan- ged into ether, the mixture becomes more denfe, and the heat which it acquires previous to ebullition is more confiderable. The affinity of the acid for alcohol be- ing increafed, the principles of this acid become fepa- rated ; fo that, on the one hand, its oxygen feizes the hydrogen, and forms much water, which is gradually volatilized ; while, on the other, the ether retaining a I S T R Y. 297 greater quantity of carbon, with which at that tempe- Alcohol. rature it can rife, affords the fweet oil of wine. Tliis *"*'"^'~~' lait ought therefore to be confidered as an ether con- taming an extraordinary portion of carbon, which givc3 it more denlity, lefs volatility, and a kmon yellow co- lour. " During the formation of the fweet oil of wine, the quantity of carbon which is precipitated is no longer in the fame proportion as during the formation of ether. " What we have here Hated concerning the manner in which ether is formed by the fimultaneous aftion of the fulphuric acid and heat, ajipears fo conformable to truth, that nearly the fame effefts may be produced by a cauf- tic fixed alkali. In this cafe alfo a kind of ether and a fweet oil of wine are volatilized, and coal is precipitated. It is therefore only by fixing the alcohol that the ful- phuric acid permits the caloric to operate a fort of de- compofition. It may alfo be urged as a proof of this affertion, that the fulphuric acid, which has ferved to make ether as far as the period at which the fweet oil of wine begins to appear, is capable of faturating the fame quantity of alkali as before its mixture with the alcohol *". « Nicho!- Ether may alfo be obtained by means of feveral other/"""' J"""" acids. The different liquids thus formed are diftin-''^''" guifhed by prefixing the name of the acid ufed in the procefs. Thus the ether above defcribed is called /u/- phurlc ether ; that obtained by means of nitric acid, ni- tric ether, and fo on. There are feveral minute ffiades of difference between thefe various ethers, which have not yet been properly inquired into. 35S Alcohol is capable of diffolving a great many bodies, ^u'^'^anc'-s A confiderable number of thefe, with the quantities fo.'^?'"^'^,''* luble, is exhibited in the following tables. a co o . I. Suljiances dijfolvcd in large families. Names of tlic Subftances. Tempi- 2^o parrs of alcohol lature. diffolve Nitrat of cobalt 54,5' 240parts copper 54.i 240 alumina 54.5 240 magnefia 180,5 694 Muriat of zinc 54.5 340 alumina 54>5 240 magnefia 180,5 'lU iron - . 1 80, J 240 copper - . 180,5 240 Acetite of lead - - «i3 copper f f Wilhcnng, Benzoic acid . - . J55.5 Phil. Tranf- Sulphat of magnefia hrii. 336. Nitrat of zinc decompofed iron decompofed bifmuth decompofed SuppL. Vot. I. Part I. PP IL CHEMISTRY. Part ir. II. Suljlantes diffbl'vid In fmall ^anthtet. * U^if Bering, Fbil. Tranf. hxii. 336. + Macquer, ibid. J Withering, Hid. § ^lacquer, UU. Niimes of the Subflarccs. Mutiat of lime Nitrat of ammonia Oxy-muriat of mercury Succinic acid Acetite of foda Nitrat of filver Refined fugar Boracic acid Nitrat of foda Acetite of copper Muriat of ammonia Arleniat of potafs Acidulated oxalat of potafs Nitrat of potafs Muriat of potafs Arfeniat of foda Barytes Strontites White oxide of arfenic Tartrat of potafe Phofphorus Nitrat of lead • lime * Muriat of mercury f Carbonat of ammonia * 140 pans of :ilcoliol at iht. boiling tempt rature difTi-lvr 240 parts 214 2 I 2 177 1 12 ICO 59 48 23 18 17 7 5 5 4 III. Suhjlances infoluble with Alcohol. Sugar of milk, Sulphat of foda. Borax, magnefia. Tartar, Sulphite of foda, Alum, Tartrite of foda and Sulphat of ammonia. potafs. lime, Phofphoric acid, barytes %, Nitrat of lead, iron (green), mercury. copper, Muriat of lead, filver, filver J, mercury, Common fait. zmc, Carbonat of potafs. potafs, foda. in Genefi?, and during the time of Abraham was even Oils, ufed in lamps *. The olive was very early cultivated, Thefe have been chiefly borrowed from tables which Mr de Morveau publifhed in the Journal de Phyjique July 1785, and which were drawn up for the moft part from the experiments defcribed in Wenzel's Treatife on AfSnities. UsaiSni'.ici. "^^^ affinities of alcohol are very imperfeftly known. Thofe ftated by Bergman are as follows : Water, Ether, Volatile oil, Sulphurets of alkalies. 3";9 360 D'lfc livery Chap. III. 0/Oils. Oil, which is of fuch extenfive utility in the arts, was known at a very remote period. It is mentioned and oil extradled from it in Egypt. Cccrops brought '"' it from Sais, a town in Lower Egypt, where it had been cultivated from lime immemorial, and taught the Athenians to e.\traft oil from it. In this manner the ufe of oil became known in Europe f. But the Greeks f- HeroJot. feem to have been ignorant of the method of procuring lib. ii 59. light by means of lamps till after the fiege of Troy j.-^'^ ^*' at leaft Homer never mentions them, and conftantly de- fcribi's his heroes as lighted by torches of wood. Oils are divided into two claffes. Fixed and Volatile; each oi which is diftinguifhed by peculiar properties. .5, I. The FIXED OILS, called alfo fut or <'A;/>r^'c/ oils. Fixed oilt are numerous, and are obtained, partly from animals and partly from vegetables, by fimple exprefiion. As in- fiances, we (hall mention whale oil or train oil, obtained, from the blubber of the whale ; olive oil, obtained from the fruit of the olive ; lintfeed oil and almond oil, ob- tained from lintfeed and almond kernels. Fixed oils may alfo be obtained from poppy feeds, hemp feeds, beech maft, and many other vegetable fubflances. All thefe oils differ from each other in fcveral parti- culars, but they alfo poflefs many particulars in com.- mon. Whether the oily principle in all the fixed oils is the fame, and whether they owe their differences to ac- cidental ingredients, is not yet completely afcertained, as no proper analyfis has hitherto been made ; but it is exceedingly probable, as all the oils hitherto tried have been found to yield the fame produfls. In the prefent ftate of our knowledge, it would be ufelefs to give Ji particular defcription of all the fixed oils, as the diffe- rences between them have not even been accurately af- certained. We (liall content ourfelves, therefore, with giving the charaflers which ditlinguifh fixed oils in ge- neral, and an analyfis of one oil, by way of ipecimen. , Fixed oils are infoluble in alcohol, which diftinguiflies-pheir pro- them from volatile oils. They are alfo infoluble in water, pertice. They have an undluous feel, are tranfparent while fluid, are deftitute of fmeli, and have a mild infipid kind of tafte. They are all fufceptible of becoming folid by expo- fure to a fuflicient degree of cold. Olive oil and al- mond oil freeze at iot degrees if. t Chaptal^t They are capable of being converted into vapour hy ^'■'""'1^'}^ heat ; but require tor that purpofe a temperature con--p"^ i ... fideraLly fupevior to that of boiling water. Olive oil .,, boils at 600'', and moft of the fixed oils hitherto tried require nearly the fame degree of heat. When in the ftate of vapour they take fire on the approach of an ignited body, and burn with a yellowilh white flame. It is upon this principle that candles and lamps burn. The tallow or oil is full converted into the ftate of vapour in the wick ; it then takes fire, and fupplies a fufhcient quantity of heat to convert more oil into vapour ; and this procefs goes on while any oil remains. The wick is neceflary to prefent a fufficient- ly fmall quantity of oil at once for the heat to adl up- on. If the heat were fufScieptly great to keep the whole oil at the temperature of 600°, no wick would be neceflary, as is obvious from oil catching fire fponta- neoufly when it has been raifcd to that temperature. ,5^ Mr Lavoifier analyfcd olive oil by burning it in pre- Analyfis of cilely the fame apparatus as that which he employed forol''^ '^''• analyfiug alcohol. The Parcir. C H E M O'l'- The quantity of oil confumeJ amounted to 15,79 *" grains troy. The quantity of oxygen gas amounted to jo,86 gr. troy. The whole amount therefore of ihi fubilances confumed during the coinbullion is 66,65 grains troy. The carbonic acid obtained amounted to 44,50 gr. There was alfo a confiderable quantity of water, the weight of which could not be accurately afcertained : but as the whole of the fubrtances confumed were con- verted into carbonic acid gas and water, it is evident that if the weight of the carbonic acid be fuhtratled from the weight of thefe fubllances, there muft remain precile- ly the weight of the water. Mr Lavoifier accordingly concluded, by calculation, that the weight of tiie water was 22,1 5 grains. Now the quantity of oxygen in 44, ^o grains of carbonic acid gas is 32,04 grains, and the oxy- gen in 22,15 grains of water is 18,82 grains ; both ot which taken together amount to 50,86 grains, precifely the weight of the oxygen gas employed. I'here does not appear therefore to be any oxygen in olive oil. The quantity of carbon in 44,50 grains of carbonic acid gas is 12,47 grains; and the quantity of hydro- gen in 22,15 grains of water is 3,32 grains; both of which, when taken together, amount to 15,79 grains, whicli is the weight of the oil confumed. It follows, therefore, from this analyfis, that 15,79 grains of olive oil are compofcd of 12,47 Carbon, 3,32 Hydrogen. Olive oil therefore is compofed of about 79 Carbon, 21 Hydrogen. « Mrm. 100* J'^r. 1734. In what manner thefe fubllances are combined, can. ypj'r^ ''o'bs learned from this analyfis. Whether they combine 1787 7»/v '^''"S'Sly' ^"d faturate each other in that proportion, as is moft probable or whether the hydrogen is combined previoufly with a part of the carbon, and that compound combining with a certain quantity of carboii, forms oil, is altogether uncertain. Yet thefe queftions are of the utmoft importance ; and till the method of folviiig them be difcovered, we never can acquire any precife ideas about the conftituent parts of a great number of fub- llances, which, though formed ultimately of the fame in- gredients, differ very much in their properties from one » another; as wax and oil; alcohol, fugar, and ether. Rancidicy. When fixed oils are expoled to the atmofpliere, they become thick, acquire a brown colour, and a peculiarly unpleafant fmell : they are then faid to be raiuij. When oil is poured upon water, fo as to form a tliin layer on its furface, and is in that manner expofed to the atmofphere, thefe changes are produced much foou- er, the oil becomes thicker, and affumes an appearance very much refemhling wax. Berthollet, who firll exa- mined theie phenomena with attention, afcribcd them to the aftion of light: but Sennebier obferved, that no fuch change was produced on the oil though ever fo long expofed to the light, provided atmofpherical air I S T R Y. was excluded ; but that it took place on the admiflion OiU. ot oxygen gas, whether the oil was expofed to the light ' 299 or not *. It cannot be doubted, then, that it is owing • -^o'. •^.• to the combination of oxygen. All fubllances that arc '''""• ■"• capable of fupplying that principle, the metallic oxides'*'^* for inllance, and feveral of the ac'ds, produce the fame effed upon oils ; and it is a known fart, that oil is capable of reducing many of the metallic oxides to the metallic Hate, and confequently that it has a ilrono-er affinity for oxygen. Mr Chaptal has fuppofed that oils become rancid merely bccaufe they contain a quantity of mucilage, with which the oxygen combines ; and that when oxy- gen combines with lixed oils, it produces a different eV- feil, converting them into what is called drying oils. It is certain that oils contain a quantity of mucilage; but fome change is evidently produced ou the oils them- felves by rancidity; for no agitation in water is capable of reftoring them to their former Hate, although water 365 deprives them of their mucilage. Drying oils, fo called Oryingoilf. becaufe they are capable of aO-j;(«^completely when fpread out, a property which renders them ufeful in painting, feem, as Sennebier obferves, to be completely deprived of mucilage ; for, in order to render an oil drying, it muft be boiled, which evaporates or decompofes all the muci- lage: they feem alfo to lofe part of their hvdroffenf. . ^ .. ,, tixed oils are capable ot dillolving fulphur at their ,66 boihng temperature. The folution is very fetid, owing rixed oils to a partial decompofition of the oil. Hydrogen gas'^''^"'"^ '"'• flies off, having a quantity of fulphur diffolved in it. P''"'^' When the folution cools, the fulphur cryllaliizfs. ,5, Fixed oils diffolve phofphorus. The folution is lu- And phof- minous, from the flow combuflion of the phofphorus. phorus. Fixed oils are capable of combining with many of the metallic oxides. The compounds are called metallic foaps. Several of the oxides are decompofed by being boded in oils. Fixed oils combine alfo with the alkaline earths and with alumiiia. The compounds are called <'a)-?adily with fixed oils, and forms the compound known by the name of foap. Potafs has never yet been decompofed. Several che- mifts, indeed, have conjeftured, that it was a compound of lime and azot ; and fome perfons have even endeavour- ed to prove this by experiment ; but none of their proofs are at all fatisfaftory. We ought, therefore, in ftridl propriety, to have affigned it a place in the firft part of this article : but this would have feparated the alkalies from each other, and would have introduced a confufion into the article, which would have more than counterba- lanced the logical exaftnefs of the arrangement. Befides, we are certain, from a variety of faiSls, that all the al- kalies are compounds : One of them has aftually been decompounded ; and the other two have been detefled in the aft of formation, though the ingredients which compofe them have not hitherto been difcovered. I S T R Y. Part. II, Whether potafs contains lime is a different queftion. Alkalies Were we to judge from analogy, we Ihould liippofe, '— ~\— -^ that the four alkaline earths, and the three alkalies, poffefs one common principle. They have a great num. ber of common properties, and perhaps ought to be claffed altogether under the name of alkaHts. That azot enters into the compofition of all thefe bodies, as I'ourcroy has conjeftured, is far from impro- bable. One alkali, as we (hall loon fee, aftually con- tains azot. But no conclufion can be drawn till future difcoveries have lifted off the veil which at j)refent ob- ftrufts our view. 380 The affinities of potafs are as follows : Its affiniti«j Sulphuric acid, Nitric, Muriatic, Sebacic, Fluoric, Phofphoric, Oxalic, Tartarous, Arfenic, Succinic, Citric, Formic, Laftic, Benzoic, Sulphurous, Acetous, Saccholaftic, Boracic, Nitrous, Carbonic, Pruffic, Oil, Sulphur, Phofphorus, Water. The place of the metallic oxides has not yet been afcertained. Sect. IL Of Soda. Soda, called mineral alkali, becaufe it is found in the earth, was known to the ancients under the names of v.'fo. and nitrum (p). It was long confounded with pot- afs; and perhaps was never properly dillinguilhed from it till Du Hamel publiihed a paper on the fubjeft in ^''f- ■ w^ T, t. r ^8' Its properties, while pure, are preciiely the fame p^ppcrtiej with thofe of potafs, excepting only that its affinity foroffoda. other bodies is not fo ftrong ; it does not, therefore, require any particular defcription. We ought to men- tion, however, that it differs from potais in one particu- lar ; potafs attrafts moifture in the air, but foda parts with it, and when expofed to the atmoiphere, foon crumbles down into a dry powder. It is capable of combining with all the fubftanceg with which potafs unites; but it forms compounds pof- feffed, in general, of very different properties from thofe of the compounds into which potais enters. It (n) If the glafs be made with foda. (o) But reddifh if the glafs be formed of foda. Klaproih. (p) The M'f,, of the Athenians was evidently the fame fubftance; and fo was the inj of the Hebrews. 391 Bifcovery of ammo- nia. Part II. CHE M Alkalies. It is reckoned more proper than potafs for foiming '~^^f^~' glafs and foap. Some cliemifts have fiippofcd that it is cornpofcd of magnefia and azot ; but tlieir proofs are infufiicient. The order of its al&nities is the fame with that of potals. Sect. III. Of Ammonia, Ammonia {qJ)i volatile alkali, or hart/horn, as it is called in commerce, is mentioned as early as the 15th century. Both Bafil Valentine and Raymond LuUy defcribed the methods of procuring it. Dr Black was the firft who diftiiiguifhed pure anummia from the car- bonat of ammonia, or ammonia combined with carbo- nic acid ; and Dr PricRlcy firll difcovered the method of obtaining it in a ftate of complete purity. To obtain pure ammonia, mix common lal ammoniac with three parts of flacked lime ; apply heat ; and re- ceive the produdl in a veffel filled with mercury ftand- ing in a bafon of mercury. A gas comes over, which • Pr/'f/J/cjinnis pure ammonia*. This gas is tranfparent like com- jiirMii; I -tnon air, and is not condenicd by cold. . -^ ■' Its fnecific gravity is 0,000752. It is to common Its pioiiei- . .' 1 ' / J ^i55 air as 000 to 1000 f. \Kirtvan en It has a very ftrong, but not unpleafant fmell. Ani- jPA/of. li.ib.mals cannot breathe it without death. When a light- ed candle is let down into this gas, it goes out three or four times fucceffively ; but at each time the flame is conhderably enlarged by the addition of another flame of a pale yellow colour, and at lall this flame dcfcends t PtlrjlUy, from the top of the vcflel to the bottom J. ii. 3S1. Water abforbs this gas with avidity. It difappears almofl: inftantly on the introduftion of a little water. From an experiment of Dr PricU'ey, it appears that water faturated with this gas is of the fpecific gravity § njJ. p. 37»- i.'4?5 J II nid. p. 377' 3K4 It=; (Oiiip This water acquires the fmell of ammonia. It has a veiy itrong difagreeable talte, and converts vegetable colours to a green. Ammonia in the ftate of gas has no effedl upon ful- phuv or phofphorus. Carbon abforbs it ; probably becaufe it contains water. Neither hydrogen nor azot produce any alteration on it ||. Alcohol and ether abforb it in confiderablequantity ^. Dr Priellley difcovered, that when tleftric cxplofions were made to pals through this gas, its bulk was gra- nent parts, dually augmented to thrice the fpace which it formerly occupieil. It was then nioftly converted into hydro- gen gas. He difcovered, too, that heat produced the very * J'jid. jSo.f^'""^ effeft *. Thefe experiments prove that hydrogen enters as an ingredient into the compofitiou of ammonia. Mr Seheele oblerved, that when ammonia was treat- ed with the oxides ot manganefe, gold, or mercury, the oxides were reduced ; th^ ammonia difappeared ; and nothing remained but a quantity of azotic gas. Thefe fa£ls induced Bergman to conjetlure, that ammonia was compofed of hydrogen and azot: a conjctlure which has been fully conlirmed by the experiments of BtrthoUet. This ingenious chemift obferved, that if oxy-muria- tic acid and ammonia be mixed, an effervefcence takes place ; azot is diftngaged, a quantity ot water formed, I S T R Y. 303 and the oxy-muriatic acid is converted into common mu- Alkahi-^. ^ riatic acid. Now the fnbftances mixed were an\moiu'a ' and oxy-muriatic acid, which is compofed of oxygen and muriatic acid ; the products were, muriatic acid, azot, and water, which is compofed of oxygen and hydrogen. The oxygen of the water was furnillKd by the acid ; the other produfts muft. have been furnilhed by the am- monia, which h. The order of its affinities h precifely the fame with that of the fixed alkalies. Chap. (q^) We have arlopted this word, which is Dr Black's, becaufe we think it preferable to ammov'uu or ammc r.iaca, the words propofed and uftd by the French chemitis. . 304 Acii!s, 3S7 P-optrties of acid.-. 3S8 Theories about the acid prin- 3S9 I.avoifisr's theory. C H E M I Chap. V. Of Acids. Substances pofl'efltd of the following properties are denominated ac'uls. 1. When aj>plied to the tongue they excite that fen- fation which is called yc/j/r or ac'td. 2. Tlicy change the blue colours of vegetables to a red. The vegetable blues employ>.(' for this purpofe are geii>;rallj- tin.?t\ire of li'.miis and fyrup of violets or of radifhes, which have obtained the name of rciigrits or tejls. If thefe colours have been previoufly converted to z great by alkalico, the acids reilore them again. 3. They unite with water in almoft any proportion. 4. They combine with all the alkalies, and mod of the metallic o.Kidcs and earths, and form with them thofe compc'unds which are called ueulral fahs. It mull bj remarked, however, that every acid does not r.ofTefs all thefe properties ; but all of them poflcfs a fuliicient number of them to dillinguifli them from other fubllances. And this is the only purpofe which artificial definition is meant to anfwer. Paracelfus believed that there was only one acid prin- ciple in nature, vhich communicated tafte and fulubili- ty to the bodies in which it was combir.ed. Becchcr embraced the fame opinion ; and added to it, that this acid principle was a compound of earth and water, which he confidered as two elements. Stahl adopted the theory of Beccher, and endeavoured to prove, that his acid principle was fulphuiic acid; of which, ac- cording to him, all the other acids were mere com- pounds. But hit. proofs were only conjedures or vague experiments, from which nothing could be deduced. Neverthelefs, his opinion, like every other which he ad- vanced in chemiftry, continued to have fupporters for a long time, and wa^ even countenanced by Macquer. At laft its defefts began to be perceived ; Bergman and Scheele declared ojienly againit It ; and their difcove- ries, together with thofe of the French chemifl;, not- withllanding the ill-natured attempts of Monnet to fnp- port it, demonftrated the falfehood of both parts of the theory, by (hewing that fulphuric acid did not exHt in the other acids, and that it was not compofed of water and earth, but of fulphur and oxygen. The opinion, however, that acidity is owing to fome principle common to l\\ the falts, was not abandoned. Wallerius, Meyer, and Sage, had advanced different theo- ries m fucceflion about the nature of this principle ; but as they were founded rather on conjefture and analogy than direft proof, they obtained but few advocates. At laft Mr Lavoifier, by a number of Ingenious and ac- curate experiments, proved, that feveral combuftlble fub- ftanccs when united with oxygen form acids ; that a great number of acids contain oxygen ; and that when this principle is feparated from them, they lofe their acid properties. He concluded, therefore, that the aci- difying principle is oxygen, and that acids are nothing elfe but combuftlble fubftances combined with oxygen, and differing from one another according to the nature of the combuftlble bafe. This conclufion has been con- S T R Y. Part II. firmed by every fubfequent obfervation. All the acids Arid*, hitherto analyfcd contain oxygen, one perhaps excepted, ' the Prtijff add, which pofielfes properties fo difl'erent from the reft, that it might, without gre;)t impropriety, be placed in a diftinft clafs. It Is probable, therefore, that thofe acids which it has not yet been polFible to decompofe cor.fift of oxygen combined with a combuf- tlble bafe : but till this analyfis Ii.is adlually been ac- coniplilhed, the theory of Mr Lavoifier cannot be con- fidered as completely demonftrated (r). 39<* The acids at prefent known amount to about 39,'''.'^"''''* molt of which have been examined within thefe 30' years. i lieir names are as h dUows I. Sulphuric acid, 21. Benzoic, 2- Sulphurous, 22. Succinic, 3. Nitric, *3- Camphoric, 4. Nitrous, 24. Suberic, 5. Muriatic, 2J- Laccic, 6. Oxy muriatic. 26. Pyromucous, 7. Pliofphoric, 27. Pyrolignous, 8. Phofphorous, 28. Pyrotartarous, 9. Boracic, 29. PrufTic, 10. Fluoric, 30- Formic, 1 T . Carbonic, 3»- Scbacic, 12. Acetic, 3^- Bombic, 13 Acetous, 33- Zoonic, 14. Oxalic, 34- Arfenic, 15. Tartarous, 35- Tungftic, 16. Citric, 36- Molybdic, 17. Malic, 37- Chromic, 18. Ladle, 38. Platinic, 19. Saccholadic, 3y- Stannic, 20. Gallic, Thefe acids (hall form the fubjeCl of the foUowinij feclions. \ Sect, I. Of Sulphuric Acid. Sulphur combines with two different quantities of oxygen : with the fmaller quantity it {orm„ Julphuroiis acid ; with thi; hrgtr fu'p/juric acid. The laft of thcle is the fubjed of the prefent feftion. ^gr The ancients were acquainted with fome of the com-'^'fcovery pounds into which fulphuric acid enters ; a/am, for in-" ," P""""' ftance, ana gr^cn -jitnol : but they appear to nave been ignorant of the acid itfelf. It Is firft mentioned in the works of Bafil Valentine, which were publiflied about the end of the 15th century. It was for a long time obtained by diftllllng green vi- triol, a fait compofed of fulphuric acid and green oxide of Iron ; hence it was called rAI of vitriol, and afterwards vitriolic acid. Another method of oVitalnlng it was by burning fulphur under a glafs bell ; hence it was called alfo oleum Julphuris per campanam. The French che- mifts in 1787, when they formed a new chemical no- menclature, gave it the name of yui^ZiuWc artf/. , At prefent it is generally procured by burning aMethoiof mixture of fulphur and nitre in chambers lined withprocuringit, lead. The theory of this procefs requires no explana- tion. The nitre fupplies a quantity of oxygen to the fulphur. k (r) This theory has been carried fo far by fome chemlfts, that they have confidered it as a conclufive proof that oxygen did not enter into the compofition of a body, if they could fhew that the body was not an acid. Thus, according to them, i8 of oxygen. He afcertained, in the iirll place *, Far. 17S1, that nitre is totally decoinpofcd by being heated with *3*' 3th of f.ilpliur. He then niixcd together 288 grains of nitre and j i of fnlphur ; and after expofing them to a fnfficient heat, he foan at the Spe- pf ftan- cific gra- dard aciu cific gra- Jari! aciii cific gra- dard acid vit," vity vity 2,000 100 1,6217 67 1,2847 34 1,9859 99 1,6122 66 1,27^7 33 |>y7i9 98 1,6027 65 1,2668 3« i>9579 97 1.5932 64 1,2589 31 1.9439 96 1,5840 63 1,2510 30 1,9299 95 1.5748 62 1,2415 29 1,9168 94- 1,5656 61 1,2320 28 1,9041 91 '.5564 60 1,2210 27 1,8914 92 '.5473 59 i,2ior 26 1,8787 9' ^^Si^'i 58 1,2009 25 1,8660 90 1,5292 57 1,1918 24 1,8542 89 1,5202 56 1,1836 23 1,8424 88 1,5112 S'i III 746 22 1,8306 87 1,5022 54 1,1678 21 1,8188 86 '.4933 Si 1,16(4 20 1,8070 85 1,4844 52 I. '53' >9 '.7959 84 ^AISS 51 1,1398 18 1,7849 83 1,4666 50 1,1309 17 1.773** 82 '.4427 49 1,1208 16 1,7629 81 1,4189 48 1,1129 '5 i,75'9 80 1,4099 47 1,1011 14 1,7416 1,7312 79 78 1,4010 1.3875 46 45 ',0955 '3 1,0X96 12 1,7208 77 '.374' 44 1.0833 11 1,7104 76 1,3663 43 1,0780 10 1,7000 75 '.3586 42 1,0725 9 1,6899 74 1.3473 4« 1,0666 8 J, 6800 73 1.3360 40 1,0610 7 1,6701 72 1.3254 39 1,05 ;5 6 1,6602 71 1.3 '49 38 1,0492 5 1,6503 70 1,31 = 2 37 1,0450 4 1,6407 69 1,3056 36 1,0396 3 1,6312 68 1,2951 35 1.0343 ^ fo far from that, we know for certain that it contains a ,yg conliderable proportion ; for when it is combined with Quantity other bodies, barytcs, for inftance, or potafp, there is a;'' ''=='1 ••'i^' coniiderable quantity of water which remains behind,).", J'"''^ and docs not enter into the combmation. Now, is ita^jj, poffiblc to determine what would be the denfity of ful- phuric acid, fuppofing it to be deprived of all water, or at leail of all water except what is neceflfary for its ev., iftence as an acid ? or to determine, how much real acid exifts in a given quantity of ilandaid acid ? Homberg firfl. attempted to anfwer this queftion. It was afterwards undertaken by Bergman, and Wenzel, and Wiegleb. They do not inform us of the quantity of water contained in a given weight of acid, but they put it in our power to find it, by informing us how much real acid is neceflary to laiurate a given quantity of potafs. Their refpetlive experiments give the fol- lowing numbers : -- • - Wenze!. I Wiegleb. I03 parts of pot-") afs require J Homb. 38.3 Berg. 78.5 82,63 I 10'. 92- Homberg ufed carbonat of potafs, and did not take into coniideration the carbonic acid driven off by the fulphuric. When this is taken in, his number fiiould be 54 inllead of 38,3. Now to difcover the quantity of real acid in any ful- phuric acid mixture, we have only to find out how much potafs it would require for faturation. The differences between the above refults are fo great, that there was reafon to fufpedl their accuracy. Mr Kirwan therefore attempted to afcertain the denfity of pure lulphuric acid by another method, and he rated it at ,,226. As this method has been already defcribed in the article Chemistry, Encycl. we cannot enter upon it here. At any rate, it would be unneceffary, as many of the principles upon which Mr Kirwan went were erroneous, as Mr Moi-veau* and Mr Keir f have fufficiently (hewn ; * Encye. and Mr Kirwan, with his ufual candour, has accord- '^ '<;'*"'• art. ingly abandoned it, and adopted another method which 't;^.'"'.''- is not liable to the fame exceptions. He diffolved 1523,5 m^^^^art Q_q 2 grains art, yf«V. ' "ienfity or diminution of bulk z ,• we fhall have f : s : n = I ) = 4 c .■>c^ The diminution of bulk, calculated according to this formula, make the lafl; column of the above table. They correfpond very well with experiment, while the meafures of alcohol are more than thofe of water, but not when the reverfe is the cafe. This Mr Poujet thinks is owing to the attraftion which exiils between the particles of water, and which, when the water is confiderable compared with the alcohol, refills the union of the water with the alcohol. By the formula s ^ 4 r n jc — 4 .4<:.x- Thi Part IT. as Morveau lias Sulphuric iilj/huric acid deprived of the water with. a folid form, or cryftallized, fliewn, is which it is ufually combined. When this glacial acid, as it has been called, is expofed to the air, it rifes in white fumes, and is foon diflipattd. This fingular effeft is produced by its violent attraiition for the water which Acid. «.£->, 308 CHEMISTRY. Sulrhucic grains of pure carbonat of potafs, dried in a red heat, in . ■^"'^ diftillcd water. The whole weighed 4570 grains. He ' took ^60 grains of this mixture, which contained 120 grains of carbonat of potafs, and faturated it with pure fulphuric acid of the fpecific gravity 1,565, which, ac- cording to the above table, contained 61 percent, of ilandard acid. The acid required for faturating the fo- exifts m atmofpheric air. When thrown into water, it lution of potafs amounted to i 30 grains, and contained felzes it with violence; a great deal of caloric is evolved, therefore 79 of ftandard. The carbonic acid difenga- fufficient, if the quantity of water be not too great, to ged was ^4 grains, and confeqiiently the quantity of al- elevate the whole in vapours * kali was 1 20 34 = 86 grains. The fulution being Sulphuric acid is capable of decompofing alcohol and ^''''""l- turbid, was diluted with 3238 grains of water. Its oils ; and when alfifted by heat, it dctompoles alfo fome -J^' '' fpecific gravity was then 1,013 ^^ ^^^ temperature of of the metaUic oxides which contain the greateft quan- ' 399 60'-'. The weight of the whole was ^694 grains. Forty- tity of oxygen ; as red oxide of lead, black oxide of man- .^fiion oj five grains of fulphat of potafs (potals combined with ganefe. It decompofes likevvife all the fulphurets and ''^"' ^j-"* fulphuric acid), diffolved in 1017 grains of diftiUed wa- phofpliurets which have an alkaline or earthy bafis. bodieJ'" ter, have the fame fpecific gravity at the fame tempera- It oxidates iron, zinc, and manganefe, in the cold, ture • from whence it follows, that the proportion of By the aififtance of heat it oxidates lilver, mercury, fait in each was equal. But in the lad folution the quan- copper, antimony, bifmuth, arfenic, tin, and tellurium. I At a boiling heat it oxidates lead, cobalt, nickel, mo- tity of fait was — -g of the whole ; therefore the quan^ lybdenum. It does not aft upon gold, platinum, tung- tityof faltin theVirftwas l^j = ^j9,52grs. Now lUn, nor titanium . ^ „ , „ ,. ^ „,. ' 23,0 It unites readily with all the alkalies, the alkaline of this weight 86 grains were alkali ; the remainder, earths, alumina, and jargonia, and with mod of the me- therefore which amounts to 70,52 grains, muft be tallic oxides, and forms falts denominatedya;^,6a/j. Thus acid. But the quantity of ftandard acid employed was the combination of fulphuric acid and foda is called /a/- 79 grains ; of this there were 8^ grains which did not phal of foda ; the compound of fulphuric acid and lime, enter into the combination, and which muft have been fulphat of lime, and fo on. It does not aft upon filica pure water : 79 parts of ftandard acid, therefore, con- nor adamanta. tain at leaft 8,5 parts of water, and confequently 100 The affinities of fulphuric acid are as follows f : parts of ftandard acid contain 10,75 parts of water. It Barytes X>i^ionary, art. Aciii. only remains now to confider how much water fulphat of potafs contains. Mr Kirwan thinks it contains none, becaufe it lofes no weight in any degree of heat below ignition, and even when expofed to a red heat for half an hour it hardly lofes a grain. This is certainly fuf- ficient to prove, at leaft, that it contains very little wa- ter ; and confequently we may conclude, with Mr Kir- wan, that 100 parts of fulphuric acid, of the fpecific gravity 2,000, are compofed pretty nearly of 89,25 of pure acid and 10,75 o^ water. This method ufed by Mr Kirwan is nearly the fame with that propofed by Mr Keir *. It feems even poffible to obtain fulphuric acid free from all the water that may not be necefTary to its acid ftate. When it is procured by diftillation from green vitriol, if the receiver be changed after the procefs has gone on for fome time, a quantity of acid is obtained in Strontites J, Potafs, Soda, Lime, Magnefia, Ammonia, Alumina, Jargonia ij ? Oxide of zinc, iron. manganefe, cobalt, nickel, lead, tin, copper, . bifmuth, 400 Its af1ini» ties. f See Bus- man and I Dr Hope, Tranf £Jiit^ jinn, de Chim. Xiii, 30S. Oxide Then fince the increafe of denfity does not change the weight of the whole, i — x y, a ■{■ b it ^s V 4'^.)' ^ V 8 0,1801 X t. /_L::i^+(2zl5£i 0,5) V 0,1152;! \©,2304> / I — 0,115a* + 0,1 152 x'- See Iri/b Tranf. HI, Part IT. Sulphurous At id. 4Ct Oxide of antimony, - arfenic, •^— — mercury, -' iilver, gold, - ■ ■ platinum, Oil, Water. Sect. II. Of Sulphurous /IclJ. Component SuLrHunous acid is compofed of fiilphur and oxy- !'•"■'" "f*^"'" gen combined : the proportions have not been afcer- cid"""^ *" tained ; but the faft itielf, and that the quantity of oxygen is lefs than what enters into fulphuric acid, has been proved beyond the polUbility of doubt. Neither can It be doubted, though the fuA has not been attend- ed to, that in this acid the fulphur and oxygen mutu- ally faturats each other ; and that fulphuric acid is not compofed of fulphur and oxygen, but of fulphurous acid and oxygen. Phofphorus is capable of decompoiing fulphuric acid by the affillance of heat, of fei/.ing a quantity of its oxygen, and converting it into fulphu- rous acid ; but upon fulphurous acid it has no efteft * Fourcroy whatever *. The affinity of phofphorus therefore for 3,nA rau. oxygen is lefs than that of fulphur; yet it is capable of taking oxygen from fulphuric acid. Is it not evident from this, that fulphuric acid is compofed of fulphu- rous acid and oxygen ? and that fulphur has a ftronger affinity for oxygen than fulphurous acid has ? For if both the acids were compofed direClly of fulphur and oxygen, it would follow from experiment, that the affi- nity of phofphorus for oxygen was both llronger and .Qj weaker than that of fulphur; which would be abfurd. Its Ui(ta. Sulphurous acid has been known fnice the time of '"/• Stahl. Scheele firft difcovered the method of obtain- ing it in quantities ; and Dr Prieltley firft procured it in a ftate of purity ; for Scheele's acid was diflolved in water. WcthoJ cf Stahl's method of procuring fulphurous acid was to procuring burn fulphur at a low temperature, and expofe to its it- flames cloth dipped in a folution of potafs. By this me- thod he obtained a combination of potafs and fulphu- rous acid ; for at a low temperature fulphur forms by combuftion only fulphurous acid. On this fait Scheele poured a quantity cf tartarous acid, and then applied a gentle heat. The fulphurous acid is in this manner dif- placed, becaufe its affinity for potafs is not fo ftrong as that of tartarous acid ; and it comes over into the recei- ver diflolved in water. It is now commonly procured by mixing with fulphuric acid oil, greafc, metals, or any other fubftance that has a ftronger affinity for oxy- gen than fulphurous acid, and applying a heat fufiicient to diftil over the fulphurous acid as it form,;. Mr Ber- thoUet has found, that fugar is the beft fubftance to employ for this purpofe. Dr Prieftley poured a little oil on fulphuric acid, ap- plied heat, and received the produft in a glafs jar filled with mercury. It was fulphurous acid free from all fu- ^0^ perfluous water, and in a gafeous form. ■Its proper- In this ftate it is colourlefs and invifible like common *'"> air. It is incapable of maintaining combuftion ; nor can animals breathe it without death. It has a ftrong and fufFocating odour. It is this odour which burning fulphur exhales. Its fpecific gravity, according to Berg. CHEMISTRY. 309 man, is 0,0^246* i accordinj* to Lavoifier, o.oozyi f.Sulrhwn'Uj Clouet and Mongc found, that by the application of ^ ^ "" ^ extreme cold it is converted into a liquid. « ,j|i /.,/«- Dr Prieftley difcovered, that when a ftrong heat niivc Attmc. applied to this acid in ciofe veffels, a quantity ot ful- ■''"•.§- 3- phur is precipitated, and tie acid is converted into ful- \_-''"""i'''3i pluiric J. BerthoUet obtained the fame refult ; but , ^J„ ^,y Fourcroy and Vauquelin could not fucceedj. ii. 3,fo. Water abforbs this acid with avidity. According to 5 Nicbol- Dr Prieftley, I too grains of water, at the temperature-/^" ■'7°"''" 54,5 ', abforb 39,6 grains of this acid. The fpecific""' ' gravity of water faturated with fulj)hurousacid is t,040||. || BcrilolUt, Water in the ftate of ice ahlbrbs it very rapidly, and is ^"'<- '^ inftantly melted. Water faturated with this acid can ''^"''' "• be frozen without parting with any of it. When wa- ter, which has been faturated with this acid at the free- zing temperature, is cxpoftd tt) the heat of 65,25', it is filled with a vaft number of bubbles, which continually increafe and rife to the furtace. Thefe bubbles are a part of the acid feparating from it. It freezes a few degrees below jZ^f. t Vourcny Sulphuric acid abforbs it at zero; but allows great ^', ^''"' V ■ r ^ Quel' part ot It to elcape at 32 * Ni- - cbol forty ibiJ^ It reddens tindure of turnfol ; but deftroys the co- * U.d. lour of fyrup of violets. It is decompofed by hydrcigen and carbon, and ful- phurated hydrogen gas, when aflifted by heatf . f UiJ. Oxygen gas gradually converts it into fulphuric acid; but this' change does not take place unlefs water be prefent. It does not feem capable of oxidating any of the metals except iron, zinc, and manganefc. When in the ftate of gas it is abforbtd by oils and ether. AVhen glafs tubes, filled with fulphurous acid in the ftate of ga,«, are expofed to a llrong heat, a quantity of fulphur precipitates, 'and the reft ot the acid is convert- ed into the fulphuric. 40^ It combines with the alkalies, alkaline earths, andl'scombi- alumina, and many of the metallic oxides, and forins ncu-"^"""'" tral falts, known by the name oi fulph'iles. ^g Its affinities, as far as they have been inveftigated. And aiEm. are as follows J : ties. Barytes, » i^'''- Lime, Potafs, Soda, Mag' A mm Alumina, Jargon ia * ? Metallic oxideS; Water. jnefia, l imonla, J" Chintt xxiir aoS. 4or S E C T. 1 1 1 . Of Nltrk Acid. There are three different fubftances compofed of a- zot and oxygen, nilrlc acid, nitrous acid, and nitrous gas. The firft contains moft oxygen; the laft contains Icaft. Nitric acid feems to have been firft obtained in a fe-oifcovery parate ftate by Raymond Lully, who was born at Ma- of nitric 3- jorca in 1235. He procured it by diftilling a mixtureciJ. of nitre and clay. Bafil Valentine, who lived in the 15th century, defcribes the procefs minutely, and calls the acid water of nitre. It was afterwards denomina- ted 310 NItr'c AckI j-iot urirg it. » Sch,eU. 4Cp f^i'covery "* its cora- porent pai ts. » regH. ii. 2S4. ■f Pbtt. •Tralf. C H E M I ted rijiia forth nnd Jpirh 0/ tiilre. The name tiilric acid was fivft given it in 1787 bv the French chemiits. Nitiic ;icid is gciicraliy obtained in large manufado- ries by diililling a mixture of nitre (t) and clay ; hut the acid procured by this prmefs is weaii and impure. Cliiiniili cenerally prepare it by diftilhng three parts of nitre and one of fulphurie ae-id in a gUfs retort. This metliod was hrtl ufed by Glauber. When obtained in thiv. manner .'t contains fome nitrous acid, which may be exj)e!led by the application of a very gentle heat *. Nitric acid is one of the moil important inftruments of analyfis which the chemift poffefTes ; nor is it of in- ferior cbnfequence when confidered in a political or com- mercial view, asit foims one of the moft efTential in- gredients of gunpowder. Its nature and compofition accordingly have long occupied the attention of philo- lophers. We faall endeavour to trace the various fteps by which its component parts were difcovered. As nitre is often produced npon the furface of the earth, and never except in places which have a commu- nication with atmufpheric air, it was natural to fuppofe that air, or fome part of the air, entered into the com- pofition of nitric acid. Mayow having obferved, that nitre and atmofpherical air were both poffeiTed of the property of giving a red colour to the blood, and that air was deprived of this property by combuftion and refpiration —concluded, that nitre contained that part of the air "jihich fupported comlnjlion, and was nscejfary for refpiration. Dr Hales, by applying heat to nitric acid, and what he called IValtcn mineral, obtained a quantity of air pof- feiTcd of fmgi'.lar properties. V/hen atmofpherical air was let into the jar which contained it, a reddiflr turbid fume appeared, a quantity of air was abforbed, and the remainder became tranfparent again *. Dr Prieftley difcovered that this air could only be obtained from nitric (u) acid; and therefore called it nitrous air. He found that when this gas was mixed with oxygen gas, nitrous acid was reproduced. Here, then, we find, that oxygen is a part of the nitric acid, and confequently that Mayow's affirmation is verified. Dr Prieftley, however, explained this fad in a diffe- rent manner. According to him, nitrous gas is com- poled of nitrous acid and phlogillon. When oxygen is added, it feparates this phlogiftqxi, and the acid of courfe is precipitated. This hypothefis was adopted \)y Macquer and Fontana ; and thefe three philofophers endeavoured to fupport it with their ufual ingenuity. But there was one difficulty which they were unable to furmount. When the two gafes are mixed in proper proportions, almofl the whole afTumes the form of ni- tric acid ; and the fmall refiduum (yith part), in all probability, or rather certainly, depends on fome acci- dental impurity in the oxygen gas. What then be- comes of the oxygen and phlogiflon ? Dr Prieftley fuppofed that they formed carbonic acid gas : but Mr Cavendifh proved, that when proper precautions are ta- ken, no fuch acid appears \. S T R Y. Part 11. Dr Prieflky had proctired his tiitrous gas by difTolving Nitnc metals in nitric acid ; during the iohition of which a , '^'^ "^- great deal of nitrous g;is eleapes. He iuppoftd that '' nitrous gas contained phlogillon, becaufe the metal was oxidated (and co' fequently, accoidiiig to the then rc- cei\ed theory, niufl have lofl phlogillon) during its for- mation. Mr Lavoifier proved that this luppohtion was ill-founded by the following celebrated experiment * : * ^•"'^ To 94; grains of nitric acid (fpecific gravity 1,316) "^',1'^ ' he added 1 104 grains of mercury. During the folution 273,2^4. cubic inches of nitrous gas were produced. Ho then diililled the fait (oxide of mercury) which had been formed to drynefs. As foon as it became red hot it emitted oxygen gas, and continued to do fo till al- mofl the whole of the mercury was revived: The quan- tity of oxygen emitted was 287,742 cubic inches. All that had happened, therefore, during the folution of the mercury, was the feparation of the acid into two parts; nitrous gas, which flew off, and oxygen, which united with the metal (x). Mr Lavoilier concluded, therefore, that the whole of the nitrous gas was derived from the nitric acid ; that nitric acid is compofed of oxygen and nitrous gas ; and that the proportions are nearly 64 parts by weight of nitrous gas, and 36 of oxygen gas. But there was one difficulty which Mr Lavoifier ac- knowledged he could not remove. The quantity of oxygen obtained by decompofing nitric acid was often much greater than what was neceffary to faturate the nitrous gas. Mr De Morveau attempted to account for this ; but without fuccefsf . Nitrous gas itfelf was \ Emyc. evidently a compound ; but the difficulty was to difco- _.f " V.-, ver the ingredients. Mr Lavoifier concluded, from an f^jt,igus. experiment made by decompofing nitre by means of charcoal, that it contained azot : and feveral of Dr Priellley's experiments led to the fame refult. But what was the other ingredient ? Mr Cavendifh had obferved, while he was making ex- periments on the compofition of water, that fome nitric acid was formed during the combuflion of oxygen and hydrogen gas, and that its quantity was increaled by adding a little azot to the two gafes before the explo- fion. Hence he concluded that the formation of the acid was owing to the accidental prefence of azotic gas. To verify this conjefture, he pafTed an eleftrical fhock through a quantity of common air enclofed in a glafs tube : the air was diminifhed, and fome nitric acid formed. He repeated the experiment, by mixing toge- ther oxygen and azotic gas ; and found that when they bore a certain proportion to each other, they were to- tally convertible into nitric acid. In one experiment, the proportion of azot to oxygen (in bulk) was as 416 to 914 ; in another, as 1920 to 4860 J. j pm, Thefe experiments were immediately repeated by Tranf. MelTrs Van Marum and Van Trooilwyk, and with near-'/ 33' ly the fame refult. The moil convenient method of performing them is the following : Take a glafs tube, the diameter of which (t) Nitre is compofed of nitric acid and potafs. (u) Or nitrous acid : for at the period of Dr Prieftley's difcovery (1772) they were not accurately diflin- guifhed. (x) We have already mentioned, in a preceding note, that this experiment was firfl made by Mr Bayen. See Part I. chap. iii. of this Article. Part II. CHEMISTRY. 311 Nitric Acid. 411 llsilrength at different fpccific gra- vities. wliicli is about the fixth part of an inch, through the cork that fliuts one enil of wlu'ch let a I'mall metalh'c con '.3775 65 1,2291 39 1.4731 90 1,3721 64 1,2209 38 i>47'9 89 1,3671 63 1,2180 37 1.4707 88 1,3621 62 1,2152 36 1,4695 87 '.357' 61 1.2033 35 1,4683 86 •-352' 60 1,2015 34 1,4671 85 1,3468 59 1,1963 33 1,4640 84 i.34'7 58 1,1911 32 1,461 1 83 ^^ii(-'(^ 57 1.1845 31 1,4582 82 i.33'5 56 I. '779 30 i'45J3 81 1.3264 55 1.1704 29 1.4524 80 1,3212 54 1,1639 28 1.447' 19 1,3160 53 1,1581 27 1,4+22 78 1,3108 52 1,1524 26 1.4373 77 1,3056 5' 1,1421 25 i»4324 76 1,3004 5^ 1,1319 24 I;4^75 75 1,2911 49 1,1284 23 1,4222 74 1,2812 48 1,1241 22 1,4171 73 1.2795 47 1,1165 21 1,4120 72 i^iT19 46 1,1111 20 1,4069 71 1,2687 45 1,1040 19 Nitric Acid Now, how much water does nitria acid cont.iin, the denfity of which is 1,5543 ? 4;^-? Mr Kirwan dried a quantity of cryftallizeJ carbonat Qm mtity of foda in a red heat, and diffblved it in water, -in fuch"' '^^.' ^"^'"^ a proportion, that 367 grains of the folution contained "'''"'^' 50,05 of alkali. He faturated 367 grains of this folu-traicd ni- tion with 147 grains of nitric acid, the fpecific gravity trie acid, . of which was 1,2754, and which, therefore, by the pre. ceding table, contained 45,7 per cent, of acid flandard. The carbonic acid driven oil amounted to 14. grains. On adding 939 grains of water, the fpecil\c gravity of the folution, at the temperature of 58,5^, was 1,0401. By comparing this with a folution of nitrat of foda, of' the fame denfity, precifely in the manner defcribcd for. merly under fulphuric acid, he fuund, that the fak con- tained in it amounted to of the whole. There 16,901 was an ex'cefs of acid of about two grains. The weio-hf of the whole was 1439 grains : The quantity of fait, confequently, was — "lilL zz 85,142 grains. The quan- 16,901 tity of alkali was 50,05 — 14 = 36^05. The quantity of ftandard acid employed was 66,7. Tire whole of which amounted to 102,75 grains ; but as only 85,142 grains entered into the conipofition of the fait, the remaining 17,608 mull have been pure water mix- ed with the nitric acid. But if 66,7 of llandard acid contain 17,608 of water, 100 parts of the fame acid mull contain 26,38*. * Irlfa One hundred parts of llandard nitric aciil, therefore, 7Vu/^. iv, - J8 compofed of 73,62 parts of pure nitric acid and 26,38 of water. But as Mr Kirwan has not proved that ni- tiat of foda contains no water, perhaps the proportion of Its a<:tion on other bodies, • PrmJ}, Dijon Aca- and Cer- ntu. \'TromJd(ir£^. 414 Its combi- And affini- ties. C H E M I of water may be greater. He lias rendered it probable, however, that nitrat of foda contains very little water. Nitric acid is decompofed by a great variety of fub- ftances. \Vlien poured upon oils, it fets them on fire. This is occafioned by a decompoiition both of the acid and oil. The o;;ygen of the acid combines with the carbon arid with the hydrogen of the oils, and at the fame time lets go a quar.tity of caloric. Hcuce we lie that the oxygen which enters into the compofitioii of the nitric acid ttill contains a great deal of caloric ; a fatt which is confirmed by a great number of other phenomena. The combuftion of oils by this acid was firft taken notice of by Borrichius and Slare ; but it is probable that Homberg communicated it to Slare. In order to fet fire to the fixed oils, it muft be mixed with fome fulphuric acid ; the reafon of which teems to be, that thefe oils contain luater, which muit be previouily removed. The fulphuric acid combines with this wa- ter, and allows the nitric acid, or rather the oil and ni- tric acid together, to adt. The drying oils do not re- quire any fulphuric acid ; they have been boiled, and confequently deprived of all moifture. It fets fire alfo to charcoal, provided it be perftSly dry. This fact was firll obferved by Prouft, and afterwards confirmed by the Dijon academicians. It fets fire alfo to zinc, bifmuth, and tin, if it be poured on them in iufion, and to filings of iron, if they be perfectly dry *. In all thefe cafes the acid is decompofed. Sulphurated hydrogen gas alfo takes fire, and burns with a ttrong flame by means of this acidf . It is capable of oxidating all the metals except gold, platinum (x), and titanium. It appears, trom the ex- periments of Scheffer, Bergman, Sage, and Tillet, that nitric acid is capable of diifolving (and confeqvently of oxidating) a very minute quantity even of gold. Nitric acid combines with alkalies, alkaline earths, alumina, and jargonia, and with the oxides of metals, and forms compounds which are called iihraU. It does not act upon filica nor adamanta. The order of its affinities is as follows : Barytes, Potafs, Soda, S T R Y. Sect. IV. Of Nitrous /teiJ, Part ir. t Dr Kofi. 5 Vauquelin^ ^nn. de Chim. xxii. los. Strontites \, Lime, Magnefia, Ammonia, Alumina, J.nrgonia y ? Metallic oxides, in the fame order as for fulphuric acid. Water. Nitrous Acid. If oxygen gas be mixed -with nitrous gas, a quanti- " ty of red fumes appear, which are readily ablorbcd by Componeat water. Thefe red tumcs are nitrous acid. jians of If a glafs veffel containing nitric acid be inverted in-"'"''"'^ »• to another vetTel containing the fame acid, and expofcd" " to the light, the inverted glafs will become partly full of oxygen gas, and at the fame time part of the nitric acid is converted into nitrous acid *. It follows, from « Schtfit this experiment, that nitrous acid contains lefs oxygen Crf//'i An- than nitric acid. Lavoifier has calculated, that it con-"''^ ijSa. ; tains fomewhat lefs than three parts of oxygen to one of azot. 4,^ Nitrous acid is of a brown or red colour, exceeding- rts proper- ly volatile, and emitting a very fuffocating and fcarcely ''". toleiable odour. When to this acid, concentrated, u fourth part by weight of water is added, the colour is changed from red to a fine green ; and when equal parts of water are added, it becomes blue +. Dr Prieil- ( Bergmar., ley obferved, that water impregnated with this acid in the ftate of vapour became firll blue, then green, and laftly yellow. A green nitrous acid became orange- coloured while hot, and retained a yellow tinge when cold. A blue acid became yellow on being heated in a tube hermetically fealed. An orange-coloured acid, by long keeping, became green, and alterwards of a deep blue ; and when expofed to air, refumed its ori- ginal colour. Thefe colours feem to depend upon the concentration of the acid. Dr PrieiUev found that water abforbed great quan- tities of this acid in the ftate of vapour ; and that w"i» n faturated, its bulk was increafed one-third. In the ftate of vapour, it is abforbed rapidly by oils. Whale oil, by abforblng it, became green, thick, and heavier It gradually decompofed the acid, re- tained the oxygen, and emitted the azot in the ilate of gas J;. _ _ i?ri,Jllej, It is abforbed by fulphuric acid, but feemingly with-'"- '"• out poducing any change ; for when water is poured into the mixture, the heat produced expels it in the nfual form of red fumes ^. The only fingular circum-^ u\j_ fiance attending this impregnation is, that it difpofesp. 144- the fulphuric acid to cr)llaUize ||. This fa^'t, firil ob-'| Uid. ferved by Dr Prieft.ley in 1777 (y), was afterwards p. ij 6. confirmed by Mr Cornette. Nitrous acid appears capable of combining with moft of the bodies with which nitric acid unites. The lalts which it forms are called nitrites. Its affinities have never been accurately examined. Bergman fuppofes them the fame with thole of nitric acid. Of Morveau had (x'l Nitre, however, afts upon platinum, as Mr Tennant has proved. Phil. Tranf. 1 797. made the fame obfervation in the Elemens de Chimie de V ^-icadtmie de Dijon. (y) Bernhardt, however, relates, in 1765, that once, when he was diftilling a mixture of ten pounds of nitre with an equal quantity of calcined vitriol, which he had put into a retort, to which was fitted an adapter be- tween the retort and the receiver, which contained a quantity of water — he obferved a confiderable quantity of a white cryftalline fait formed in the adapter, while the liquid acid pafTed as ufual into the receiver. This fait was very volatile, fmoked ilrongly when it was expofed to the air, and exhaled a red vapour; it burnt, to a black coal, wood, feathers, or linen, as fulphuric acid does ; and where a piece of it fell, it evaporated in form of a blood red vapour, till the whole of it difappeared. Half an ounce of thefe cryftals difiblved in water with fpurt- ing and hifling, like that of a red-hot iron dipped in water, and formed a green nitrous acid. Some of this fait being put into a bottle, which was not well flopped, entirely vanilhed. Thefe cryftals were evidently the fame with Dr Prieftley's. See Keir^s Diffiorn'ry. Part 11. C H E M I 419 ) Ibid. p. 407. Of Nilrout Gas. Nitrous gas was firft obtained hy Dr Hales, but Its properties were difcovcred by Ur PriciUey. It may be pnicgred by difTolving mttals in nitric or iiitruus acid, and cattliiiig the produiil by means of a pneuma- tic apparatus. As nitrous acid is formed by combining nitrous gas and oxygen, it is evident that nitrous gas contains lefs oxygen than nitrous acid. According to Lavoifier, it is compofed of two parts of oxygen and one of azot. Nitrous gas is elaftic, and invifible like common air. Itsproi'er- It extinguilhes light, and inllantly kills all thofe ani- *"*■ mals that are obliged to breathe it. Its fpccific gravi- • On Phlo- 'y» according to Mr Kirwan, is 0,001458 *. tiRcn, p. 28. Dr Prieftley found that water was capable of abforb- ing about one-tenth of nitrous gas, and that by the ab- ♦ PrUfiley fu'ption 't acquired an aftringent tafte f. Water parts ,61;. with all the nitrous gas it has imbibed on being frozen |. Neither phofphorus nor fulpbur leem capable of de- compofing nitrous gas. Mr Linck, profeffor at Roftoc, found, that three parts of nitrous gas and two of hydrogen gas, obtained by fulphuric acid and iron, are Icarcely, or not at all, diminiflied when expofed to day-light over water. Com- mon air Is not more dminilhed by this admixture kept a long time : but the mixture itfelf of thefe two gafes is diminifhed by the addition of new portions of nitrous gas. Mr Linck concludes, from this obfervation, that part of the oxygen of the nitrous gas combined with the hydrogen and formed water, and that the remaining oxygen and azot formed a mixture fimilar to the air of the atmofphere. Mr Vauquelin had previoufly made the fame obfervation. The affinity of hydrogen, there- fore, for oxygen is greater than that of azot §. Oils imbibe nitrous gas with avidity, and dccompofe it. Nitric acid abforbs a vaft quantity of it, and is by that means converted into nitrous acid. — Sulphuric acid alio abforbs It. The moft important property of nitrous gas is that of combining inllantly vvitii oxygen gas, and forming nitrous acid, which is inllantly abiorbed by water. This property induced Dr Prieftley to ufe nitrous gas as a tcft. of the purity of common air. He mixed together equal bulks of thefe fubftances, and judged of the pu- rity of the air by the diminution of bulk. The appa- ratus uftd for this purpofe, which confifls of a gradua- ted tube, has been called a eudiometer. This eudiome- ter has been greatly improved by Fontana, but it is llill liable to uncertainty in its application. Perhaps the bell eudiometer is fulphuret of potafs, which, as Mor- veau has dlfcovercd, ablorbs, on the application of heat, the whole oxygen in a given bulk of air almoft inftan- taneoufly. Dr Prieftley found that nitrous gas was decompofed by paffing eleftric explofions through It. Let us now confider In what manner oxygen and azot are combined in the three fubftances which have been juft defcrlbed. Manner ia It can hardly be conceived that azot is capable of which azot combining with three'different proportions of oxygen, and oxygen jj,)(} ^f being faturated with each: it Is furely much ,yj '' more probable, that in nitrous gas the oxygen and azot faturate each other dlredtly and completely ; that ni- trous acid is compofed of nitrous gas and oxygen, and SuppL.VoL, L FartL f NIchol fans 'Jtiur, a. ■)%. 410 The eudio- STRY. 3T3 nitric acid of nitrous add and oxygen. And tMs fup- Muriatic pofition is confirmed by confidering th.it ilie ftrength ''^"^- , of affinity by which tlie oxygen is retained in each of """"^ thefe fubftances is very different. Sorrlc lubftances, as light, are capable of decompoling nitric acid, by fe'zing fome ot its oxygen, and of converting it into nitrous acid ; but they have no effcdl whatever upon nitnnis acid or nitrons fjas. Others, as bifniuth, copper, jihof. phorus, and fulphur, are capable of decompoling both nitric and nitrous acids, but are incapable of altering nitrous gas : And others, again, as carbon, zinc, and Iron, are capable of (lecompoling all the three. Every body which is capable^ of dccompofing nitrous add is capable alfo of dccompofing nitric acid ; and every body that decomjxjfes nitrous gas is capable alfo of dccom- pofing the other two. But the reverfe of this is not true. The affinity of oxygen, tiien, for azot, nitrous gas, and nitrous add, Is different : oxygen has a ftronger affinity for azot than it has for nitrous gas, and a ftronger affinity for nitrous gas than for nitrous add. But if all thefe bodies were dircft combinations of azot and oxygen, how could this difference of affinity take place ? Is it reafonable to fuppofe that a fubftance has a ftronger affinity for one proportion of any other body than for another proportion? or that, if fuch a difference exifted, the ftrongeft affinity (hould not always prevail? Mix together nitric add and nitrous gas in proper pro- portions, and the whole mixture is converted into ni- trous acid : but mix nitrous and nitric adds together, and no change whatever is produced. In the firil cafe. Is It not evident that the affinity of nitrous gas for oxy- gen is greater than that of nitrous acid ; that therefore It decompofes the nitric acid, deprives it of oxygen, and leaves It in the ftate of nitrous acid? But, in the fecond cafe, no change can take place, becaufc nitric acid is compofed of nitrous acid and oxygen ; and it would be abfurd to fuppofe, that nitrous acid has a ftronger affinity for oxygen than nitrous acid lias. But were azot and oxygen capable of uniting In various proportions, why lliould not a mixture of nitric and ni- trous acids, or of nitrous gas and nitrous acid, form new fubftances ? And why are the only fubftances which appear in decompofitions nitrous acid and nitrous gas ? Surely thefe reafons are fufficient to fhew us, that thefe bodies are combined In the following manner ; Azot and 1 ^ 0> torm nitrous cas ; xygen y ° ' Nitrous eas \ c ■ • . , J ° > form nitrous acid ; and oxygen \ ' Nitrous add 1 c ■ ■ ■ , _ I J- form nitnc acid, and oxygen J Perhaps there may be even more links in the chain than we are aware of. The dephlogifticated nitrous air of Dr Prieftley, which Dieman and Van Trooftwyck have lately proved to be compofed of 37 parts of oxy- gen and 6j of azot, and of which little more is known than that It fupports flame. Is noxious to animals, ab- forbed by water, and only obtained by means of fub- ftances capable of dccompofing nitrous gas — perhaps this air is compofed direttly of oxygen and azot, ni- trous gas of this air and oxygen, and fo on. There may be even links ilill farther back than that. Sect. V. 0/ Muriatic JcU. •lit Muriatic acid appears to have been known to Bafil Difcovtry Valentine ; but Glauber was the fiift who extrafted it"f marutic from acid. 314 CHEMISTRY. , Part If Muriatic from common fait by means of fulphuric acid. Com- is always called by that name) is generally of a pale Ox)- muria . ''^ , mon fait is compofed of muriatic acid and fuda, for yellow colour, owing, ae Dr Pricflley fuppofed, to fome '"^ '^"J- which lad fubftance fulphuric acid has a ilronger afiini> earthy matter difl'olved in it ; but much more probably """"v— ty. This acid «as firil called^wV// of fall, afterwards to its having abforbed a quantity cf oxygen, for which • From ««-»""■'"« ocitl, and now, pretty generally, mur'nuic acid*, it has a Ibong affinity. Indeed, that tliij is the caufe ria. It is fonietimes prepared by mixing one part of com- ap])ears evidently from Dr Prieftley 's own obftrvations ; mon fait with feven or eight prrts of clay, and diftilling for it was deftroyed only by thofc bodies which had a the mixture. The clay, in this inilance, is fuppofcd to Ilronger affinity for oxygen. It is very volatile, as acl chiefly by means of the fulphuric acid which it al- might be expefted, conitantly emitting white fumes of ways contains (z) : But this fubjeft ftill requires far- a peculiar and unpleafant odour. ther elucidation. By thefe pioccITes, muriatic acid is Muriatic acid is capable, by the affiftance of heat, oflsa(aion obtained diffolved in water. Dr Prieftley dilcovered, oxidating the following metals : Iron, tin, lead, zinc, °" "'her that by applying heat to this folution, and receiving the bifmuth, cobalt, nickel, manganefe, antimony, arfenic. "' product in veffels filled with mercury, a gas was procu- Several of thclc, as iron, for inftance, it oxidates even 4>3 Its proper ties. red ; which gas is muriatic acid in a ilate of purity. Muriatic acid gas is invifible and elalllc, like com- mon air. It deitroys life and cxtinguiflics flame. A candle, juft befoie it goes out in it, burns with a beau- tiful'green, or rather light bine flame ; and the fame ^ Pritfiliy, flame appears when it is fuil lighted again +. "•»93- - - Tranf, iv. without the afliftance of heat. At a boiling heat, it oxidates filver and copper. It has no atlion on gold, platinum, mercury, tungften, molybdenum, tellurium, titanium. Its atlion on ura- nium has not been tried. In the Hate of gas, it appears to decompofe alcohol The fpecific gravity of muriatic acid in the Rate of and oils by its afiinity for water * PrunU' gas is, according to Mr Kirwan \, 0,0023x5, which is nearly double that of common air. Water abforbs this gas with avidity. Ten grains of water are capable of ablorbing ten grains of the gas. The folution thus obtained occupies the fpace of 13,3 grains of water nearly. Hence its fpecific gravity is It 'i<"}f IS capable of diffolvintr a little fulphat and fluat + " ^''' „ c V jr-.r + see feet, 01 lime, and arleniat 01 mercury. ■ It combines with the alkalies, alkaline earths, alumi- na, and jargonia, and with moft of the metallic oxides, and forius neutral falts, known by the name olmurlats. 416 Morveau hrft fhewed, that this acid, in the Hate of Deflroys i,;oo, and the denfity of the pure muriatic acid in it gas, neutralized putrid miafmata, and by that means 1'"'"'' '"'* 7r§'T«">.'M'°3HA)- deftroyed their bad eft'eds. In 1 773, the cathedral of """^'*- vol. iv. '* As muriatic acid can only be ufed conveniently when Dijon was fo infefted by putrid exhalations, that it was diflblved in water, it is of much confequence to know deferted, after feveral unfuccefsful attempts to purify it. how much pure acid is contained in a given quantity of Application was made to Mr Morveau to fee whether 424 liquid muriatic acid of any particular denfity. he knew any method of deftroying thefe exhalations. Quantity nf J^qw the fpecific gravity of the pureft muriatic acid He poured two pounds of fulphuric acid on i\ii. pounds It contained jj^^^ can eafily be procured and preferved, is 1,196 ; it of common fait, contained in a glafs capiule, which had various would be needlefs, therefore, to examine the purity ot been placed on a few live coals in the middle of the denfitits. any muriatic acid of fuperior denfity. Mr Kirwan cal- church. He withdrew precipitately, and fliut all the culated that muriatic acid, of the denfity 1,196, con- doors. The muriatic acid gas foon filled the whole ca- tains rVo pai'ts of acid of the denfity 1,500, which he thedral, and could even be perceived at the door. After took for the ftandard ; then, by means of experiments, 1 2 hours, the doors were thrown open, and a current of he formed the following Table : air made to pafs through to remove the gas. This de- too parts, at the fpe- cific i;ra- viiy 1,196 Contain of ftan. lard acid 103 parts, at the fpe- cific gra- vity Contain of llan- c'ard acid 100 parts, a* the Tpe- cific gra- vity Contain of Han- dard acid 49 1. 147 37 1,1036 26 1,191 48 1,1414 36 1,0984 25 1,187 47 1,1396 35 1,0942 24 1,183 46 1,1358 34 1,0910 23 I. "79 45 1,1320 33 1,0868 22 i>i7S 4+ 1,1282 32 1,0826 21 1,171 43 1. 1244 31 1,0784 20 1,167 42 1,1206 30 1,0742 19 I, "63 41 i,ti68 29 1,0630 16 1,159 4^ 1,1120 28 J, 0345 10 i-'JS 39 1,1078 27 1,0169 5 i.iyi ?« 1 ftroyed completely every putrid odour -j- The affinities of muriatic acid are as follow Barytes, Potafs, Soda, Strontites f , Lime, Magncfia, Ammonia, Alumina, Jargonia II, _ Metallic oxides as in fulphuric acid, ■^''"' ' .. --, '^ Chim. Xill. \V ater I Jour, de 427 ItsaSnitiei, 5 Drliofe. Vaiiqiiclinf »0S. Sect. VI. Of Oxy-murlattc Acid. 41S Put into a glafs retort one part of the black oxide Difcovery of manganefe and three parts of muriatic acid ; place ^"4 P'*?*' ■ • r . , 1 ■ r 1 I 11- 1 • 1 ration 01 it in a fand-bath in Inch a manner that the liquor which (,jy.„uf;i. Muriatic acid (for this folution of the acid in water rifes up into the neck of the retort may fall back again tic acid. into (z) Morveau has (hewn, that even alumina contains fulphuric acid, provided a precipitation, on adding mu- riat of barytes, be a fufficient left. (a) For let D =: the denfity of a mixture; m the weight of the denfer ingredient; iits denfity; /the weight of an Part II. CHEMISTRY. 419 !ts compo Ccion. Oxy-muri- into tKc vtfTcl ; and npply a fmall receiver, with a little atic AciJ. ^yater in it, luted to the retort merely by a fillet of *"""*'""" brown paper. In about a quarter of an hour the re- ceiver will appear filled with a yellow-coloured gas; it is then to be removed, and others applied fucceilively till the operation be fini(hed. This gas is oxy-murlatic acid, firll difcovcred by Scheele, while he was making experiments on manga- nefe, and called by him dephlogijVicUed muriatic acid, be- canfe he thought it muriatic acid deprived of phlo- gifton. The French chemitls called it osygenala! muri- atic acid, which l)r Pcarfon contrafted into oxy-miiria- tic acid ; and this lall name we have adopted, becaufe it is fhorter and equally dlilincl. The true theory of the formation and compofition of this acid, wllich was firll given by Berthollet, will appear from the following facts : The black oxide of manganefe is, during the proeefs, converted into tuhite oxide, and mull therefore have given out a quantity of oxygen. When oxy-muriatic acid dilTolved in water is prefented to the ligiit in a vefiel half empty, oxygen gas is difengaged and floats above, and the acid is con- verted into common muriatic acid : Confequently oxy- muriatic acid is compofed of muriatic acid and oxygen. Black oxide of manganefe is compofed of white oxide and oxygen ; muriatic acid has a llronger affinity for oxygen than the white oxide ; during the dillillation the black oxide is decompofed, the oxygen combines with muriatic acid, and the produdl is oxy-muriatic acid gas. Oxy-muriatic acid gas is of a yellow colour. It fup- ports flame, but cannot be breathed without proving noxious. The death of the ingenious and induHrious Pelletier, to whom we have fo often referred, was occa- fioned by his attempting to relplre it. A confumption was the confequence of this attempt, which, in a fliort time, proved fatal. It does not luute readily with water. Scheele found, that after Handing ! 2 hours over water, iths of the gas were abforbed : the remainder was common air, which no doubt had been contained in the velfel before the operation. Berthollet furrounded feveral bottles con- taining it with ice : as loon as the water in thefe bottles was faturated, the gas became concrete, and funk to the bottom of the veffcls ; but the fmalleft heat made it rife in bubbles, and endeavour to efcape in the form of • J^urn. * gas*. Wellrum obferved that it became folid when + "y '' J expofed in large veffcls to the temperature of 40°; and fMjti'i:, ^''*t t'l'^" ■'^ exhibited a kind of cryllallization ■]-. The xsxvii. 3Si.fpecific gravity of water faturated with this gas, at the 430 Its prop;-- ties • Morveau^ 5«5 temperature of 43'', 18 1,0:3 *• Water impregnated Oiy-mnri. with it has not an acid, but an auftcre tafte f , unlike .°"^ - • '■c'd-^ that of other acids. « » ,111. T , 111 I • , , Btrtbollet, U renders vegetable colours tobite, and not red, as jaurn. de other acids do; and the colour thus dellroyed can '"^.-.y- ' ?85. neither be rellored by acids nor alkalies. It has the t •^^*"''' fame tffefts on yellow wax. If the quantity of vegetable colours to which it is applied be fuffic'ently great, it is found reduced to the Rate of common muriatic acid. Hence it is evident, that it dellroys thefe tol.iurs by communicating oxygen. This property has rendered oxy-muriatic acid a very important auicle m bleaching. Nitrous gas, hydrogen, fulphur, luiphurous acid, and phofphorus, deeompole this acid, by depriving it of its oxygen, and leaving the muriatic acid in a ieparate (late. Phofphorus, however, does not produce this efTeft fo readily, except when aflrilled by heat*. When muriatic acid is mixed with nitric acid, the f""c." compound has precifely the fmell and the qualities of Wfjoi/. oxy-muriatic. It can fcarcely be doubted, therefore, •'""""i'' that as far as it a6ls as an acid, different from the mu-*^'" riatic and the nitric, it is nothing elfe but oxy-muriatic Nitro-nMu acid, riatic acidi This mixture of the two acids was formerly called aqua regia ; but at prefent it is called by the French chemifts nilro-tnurialic acid. It is firll mentioned by Ifaac the Hollander, and feems to have been known be- fore the muriatic acid itfelf. It was prepared by pour- ing nitric acid on common fait. The nitric acid de- compofes the fait, and part of it unites with the muri- atic acid thus fet at liberty- a-i% Oxy-muriatic acid oxidates all the metals (except, Its aiSiin perhaps^ titanium) without the affillance of heat. "" 9'''=r It decompofen red fulphuret of mercury, or cinnabar, ''"^^^ which neither fulphuric nor nitric acid is able to ac- complifh § , , r ■ . § B'rf«."». All the fubflances placed before muriatic acid In the table of the affinities ot oxygen, are capable of decompo- fingthis acid. Many of them, when plunged into it while in the flate of gas, aftually take fire. Wellrum obfer- ved, for inflance, that when pieces of wood were plun- ged into this gas, they took fire ; that arfenic burned with a blue and green flame ; bifmuth, with a lively bluifli flame ; nickel, with a whire flame, bordering dn yellow ; cobalt, with a white flame, approaching to blues ziuc, with a lively white flame ; tin, with a feeble bluifli flame ; lead, with a fparkling white flame ; cop- per and iron, with a red flame : that powdered char- coal took fire in it at the temperature of 9-0", and that ammonia produced with it a loud detonation |{. || jcurn.dt R r 2 With Pl'iffi^-'c, xxxvii. 3S51 m -^m' an equal billk of Vsfater; and m', d', and /', the fame elements of the rarer : Then D = . . In the above cafe, m-<-m' = 20, and / -f / = 13,3. Then D = = 1,5, Now to find the fpecific gravity of the condenfed muriatic acid gas, we have from the above equation / = tt := — ~ = 3,3 j and d =: m 10 -j-^ =: 3«P3' ^'^ I''lft> TranfaSioni, vol. iv. This calculation, however, is formed upon the fuppofition that the water fuflfers no condenfation at all a fuppofition certainly contradifted by every analogy, and which, as Mr Keirhas Ihewn, the experiments mentioned in Mr Kirwan's firft paper are tnfuMcient to prove. 3i6 > CHEMISTRY. Part IL Oxy-muri- With alkalie'!, earths, and metallic oxides, it is ca- out of the bottle ; they were ftrongly inflammable, and Pliof^Iiorle. atic Acid, p^y^. ^,f combining and forming neutral falls, which probably, therefore, pure hydrogen gas. The liquor, ' have been called oxy-i)hiriats. Acid. -V" Its • Vauqiie' fin, Ann di Chtm. xxii. ac8. ffiuitiei. The affinities of this acid, according to Lavoifier, are as follows : Alumina, Jargonia * ? Ammonia, Oxide of antimony, fdver, arfenic, Barytes, Strontites ? Oxide of bifmuth, Lime, Oxide of cobalt, ■ copper, ■ ■ tin, iron, Magnefia (b). Oxide of nianganefe, — -^ — mercury, molybdenum, nickel, gold, — platinum, lead, Potafs, Soda, Oxide of tungften, zinc (c). Of*Wom- The component parts of muriatic acid are ftill ira- perfeftly known. Dr Girtanner pretended, about the year i 790, that he had decompofed it ; and that it con gradually loll its odour of iulphurated hydrogen gas, and after iome days ImtUcd very much like ftagnant rain-water. As the bubbles ceaied to be produced, it recovered its tranfparency. On evaporating a fmall quantity of this iolution in a watch-glafs to drynefs, a bitter deliquefcent fait was left behind. On this fait a little fulphuric acid was dropped, and paper moiften- ed with ammonia was held over the glafs ; white va- pours were immediately formed over the glafs ; and confequently fonie volatile acid was feparated by the fulphuric acid. Mr Lambe evaporated about eight ounce meafnres of the lame liquor, and, as before, drop- ped a little fulphuric acid on the reiiduum ; a ftrong effervefcence was excited, very pungent acid fumes arofe, which, from their fmell, were readily known to be mu- riatic. The fame truth was eftabliflied beyond a doubt, by holding a bit of paper moillened with water, which made the vapours vifible in the form of a grey fmoke ; a diftinguifliing charafteriftic, as Bergman has obferved, of the muriatic acid. — When manganefe and mercury were difTolved in fulphurated hydrogen gas, the falts formed gave the fame unequivocal marks of the pre- fence of muriatic acid *. * tamht, Shall we conclude from thefe fafts, that the bafis of'^'''- muriatic acid is fulphurated hydrogen ; that muriatic acid is fulphurated hydrogen combined with oxygen ; that this combination takes place during the folution of the iron ; and that the efcape of hydrogen is owing to the decompofition of the water ? fonent y>a '5 of muriatic acid. Sect. VII. Phofphoric Add. 435 Phosphorus is capable of forming combinations'-'"'^'''''^ lifted of hydrogen combined with a greater proportion with two different quantities of oxygen ; with the larger"^ ^ o p e- of oxygen than enters into the compofition of water, it forms phofphoric ; and with the Imaller phofphorous He pafled eleftrical explofions through muriatic acid, acid. and obtained a quantity of oxygen and hydrogen gas. Phofphoric acid was unknown till after the difcovery But a repetition of thefe experiments (hewed, that the of phofphorus. Boyle is perhaps the firft perfon who gafes were owing, not to the decompofition of the acid, mentions it : he difcovered it by allowing phofphorus but to that of the water with which the acid was com- to burn flowly in common air. But Margraf was the bined. firft perfon who examined its properties, and difcovered The experiments of Mr Lambe (d) have lately opened it to be a peculiar acid, a new and unexpedled path, which feems to lead direft- It may be procured by expofmg phofphorus to a mo- ly to the difcovery of the component parts of this acid, derate heat : the phofphorus takes lire, combines with He found, that when iron was acted upon by fulphu- oxygen, and is converted into an acid. ^36 rated hydrogen gas, a fubftance was produced which It may alfo be prepared by expofing phofphorus Method of poffefied all the properties of oxy-muriat of iron (oxy- during fome weeks to the ordinary temperature of the pi'«P*'"'6 '' muriatic acid combined with iron). The fulphurated atmofphere, even in winter; when the phofphorus un- hydrof en gas which he ufed was obtained from fulpliuret dergoes a flow combuftion, and is gradually changed in- of iron, formed by fufing equal parts of iron and flowers to a liquid acid. For this /purpofe, it is ufual to put of fulphur ; and it was extricated by diluted fulphuric fmall pieces of phofphorus on the inclined fide of a glafs acid. In a folution of this gas in diftilled water, he di- funnel, through which the liquor which is formed drops jrefted iron filings, previoully purified by repeated wafh- into the bottle placed to receive it. From one ounce ings with dillilled water. The bottle was filled with of phofphorus about three ounces of acid liquor may be the folution, and corked. The iron was prefently aifed thus prepared, called phofphoric acid by deliquefcence. upon ; numerous bubbles arofe, which drove the cork Scheele has contrived another mode of obtaining the pliofphoric (b) According to Trommfdorf, oxy-niuriatic acid is incapable of combining with magnefia. Ann. de Chim. xxii. 2 1 8. ' (c) This is the order of the affinities of nitro-muriatic acid. Many fafts (fome of which Ihall appear after- wards.) concur to prove that the affinities of the oxy-muriaiic acid are the fame, and indeed that they are the fame acids. (d) Analyfis of the waters of two mineral fprings at Leminton Priors. Manchejler Memoin, vol. V. fart I ft. 1 Part ir. CHEMISTRY. Phofphoric phofphoric add from phofphonis witliout combuftion, , ■'^'■ '^- by the mere adioii of the nitric acid on phofphonis*. • On Vire ^'" Lavoifier has repeated and dcfcribed tliis procels-f-. § Ixxvii. He put two pounds of nitric acid, the fpecific gravity ^ Mem. A. of which was 1,2989?, into a retort, the contents of tmi. i-jho. ^yluYli were equal to fix or feven French pints, and to whicii a balloon was fitted. Having placed this retort in a fand-bath, and brought the heat of the acid contained in it to 133 J deg he added fucccffively fmall quantities of phofphorus, about 10 or 12 grains at a time, until he had diffolved 2;^ oz. At iiril the tfFervefcence was great, but at laft he was obliged to apply heat to effeiSl the folution. The operation Lifted 17 or 18 hours. A good deal of nitrous acid had paflTed into the receiver. He then poured the contents of the retort into a fmaller retort, and evaporated by means of a llronger heat, un- til the phofphoric acid began to diftil in white vapours. The remaining acid was fo thick that he could not pour it out of the retort, and therefore could not afcertaiii its quantity ; but he fuppofes it might be 8 or 9 oun- ces, in wliich he thinks there were about 2\ oun- ces of phofphorus ; the remaining ^ ounce being fup- pofed to have evaporated. The quantity of oxygen imbibed he reckons at 34^ ounces, and the quantity of water at about 2 ounces. Lavoifier computes that phofphoric acid contains ico 437 parts of phofphorus and 154 of oxygen. Its proj-er- The colour of this acid is white; it has no fmell, has '*'■ an acid talle ; but is not corrofive (e). It is exceedingly fixed. When expofed to the fire in a matrafs with a long neck, it lofcs at firft the greater part of its water ; then an odour of garlic is felt, ow- ing to lome phofphorus, from which it is exceedingly difficult to clear it entirely ; there is likewife a fmall quantity of the acid volatilized along with the water. The liquor then becomes thick and milky: fmall lumi- nous decrepitations take place from time to time, and they continue for fome time after the veflc:l is taken from the fire. If the matter be then put into a cru- cible, and placed among burning coals, it firft boils vio- lently, and gives out a vapour which tinges flame green, and is at lall converted to a v,'hite tranfparent glafs, in- foluble in water. The fpecific gravity of this acid in a ftate of dry- \ 'Birgmnn. nefs is 2,687 J, that, of phofphoric acid by deliquef- J Monctiu, cence 1,417 J. It is capable of cryftallizing ; its cry- ftals are quadrangular prilms terminated by quadrangu- lar pyramids. Phofphoric acid obtained bv deliquefcence, when mix- ed with an equal quantity of diftilled water, acquired fo little ieat as to raife the thermometer only one degree, as Mr Sage obferved. Mr Lavoifier raifed Reaumur's thermometer from S" to 14° or 15*^ by mixing phofphoric acid boiled to the confiftence of a fyrup, with an equal quantity of water ; and from 8'^ to 32° or 33° when the acid was as thick as turpentine 1). Phofphoric acid is capable of oxidating iron, tin, lead, zinc, antimony, bifmuch, manganefe. When fu- fed with feveral of thefe metals, as tin, lead, iron, and zinc, it is converted into phofphorus; a proof that they have a ft.ronger af&nity for oxygen. 3n [I Keir's Uiiiiotrary 45 S ts at'-tioii in other iod:es. 439 Its affini- ties. It does not adt tipon gold, platinum, filvcr, copper, Boracic mercury, arfenic, cobalt, nickel. It appears, however, , ^'^"'- _ to have fome aiSlion on gold in the Jry -way, as it is ' called; tor when fufed with gold-leaf it affumes a purple colour; a proof that the gold has been oxidated. It is capable of combining with alkalies, alkaline earths, alumina, and metallic oxides; and of forming falls known by the name ol phofj>hats. Phofphoric acid, by the aflillaiice of heat, is capable of decoinpofing glafs. Its affinities are as follows : Lime, Barytes, Ktrontites*, « jy„^,_ Magnefia, Tranf.E- Potafs, dii.ii. Soda, Ammonia, Alumina, Jargoniaf, \ Vauqur- Metallic oxides as in fulphuric acid, ''". ■^'"'- "/' Water. '-^■^"'- ''^"• The Phosphorous Acid is formed when phofpho- .' rus is expofed to a flow fpontancous combuftion at the Pt ofpho- temperature of the atmofphere; but it gradually abforbs rous acid. more oxygen, and is converted into phofphoric acid. Concerning phofphorous acid nothing of any confe- queiice is at prelent known, except that it contains Icfs oxygen than phofphoric acid. Sect. VIII. Boracic Aciil. 441 The word borax fiift occurs in the works of Geber, Bor.i. an Arabian chcmift of the loth century. It is a name given to a fpecies of white fait inuch ufed by various artifts. Its ufe in foldcring metals appears to have been known to Agricola. Borax Is found mixed with other fubftances in Tiil- bet. It feems to exift in fome lands adjacent to Likes, from which it is extrafted by water, and depolited hi thofe lakes; whence in fummer, when the water is fhal- low, it is extrafled and carried ofl'in large lumps. Some- times the water in theielakes is admitted Into refervoirs, at the bottom of which, when the water is exhaled by the fummer's heat, this fait is found. — Hence it is car- ried to the Eaft Indies, where It Is in fome meafiire pu- rified and cryftallized: in this ftcite it comes to Europe, and Is called tinea!. In other parts ot Thibet, it feems, by accounts received from China, they dig it out of th<; ground at the depth of about two' yards, where they find It in fmall cryftalline maffes, called by the Cliinefe mi pc/uii, houi poun, sndpinpoun; and the earth or ore IS Cidltd poijnxij i, i Kirvau\ Though borax has been in common ufe for nearly .'}-'^""'''''"%J'> three centuries, it was only in 1702 that Homberg, by""^'" diftilling a mixture of borax and green vitriol, difcovered nilcovery the boracic acid. He called it narcotic or fedative fait, nf tioracic from a notion of his, that it poifeifed the properties in-^'^'''' dicated by thefe names In his opinion, it was merely a produft of the vitriol which he had ufed ; but Le- mtry the Younger foon after difcovered, that it could likewife be obtained from borax by means of the nitric and muriatic acids. Geoffroi afterwards difcovered, that (e) We have obferved, however, that when very much concentrated it deitroyed the texture of vegetable fub- ftances, paper for inflance, very completely. Acid. 44.1 Attempts 318 ^ C H E M I Boracic that borax ContEineJ foda : and at laft Baron proved, by a number of experiments, that borax was compofed of boracic acid and foda ; that it mi^jht be reproduced by combining thefe two fubftanccs — and that therefore the boracic acid was not formed during the deconipofi- tion of borax, as furiner chemitts had imagined, but was a pecuh'ar fubllance which pre-exiited in that fait. This conclufion has been called in queftion by Mr Ca- to prnve det * ^vho affirmed that it was compofed of foda, the that It does . . ' , , , . , , '^ / J not exill in "vitnfiable tartb oj copper, another unknotvn metal, and mu- borax ; riatie acid. But this aflcrtion has never been confirmed • Jixtrn-de Jjy 3 fingle proof; Mr Cadet has only proved that bo- -V' '7*^' racic acid fometimes contains copper; and Beanme's experiments are fufficient to convince us that tins metal is merely accidentally prefent, and that it is probably derived from the veflels employed in cryftallizing borax: That boracic acid generally contains a little of the acid employed to feparate it from the foda, with which it is combined in borax : And that crude borax contains a quantity of earth imperfectly faturated with boracic acid : — All which may be very true ; but they are al- together iiifufficient to prove that boracic acid is not a peculiar fubflance, fince it difplays properties different from every other body. And to MelTrs Exfcliaquet and Struve have endeavoured, on prove that the other hand, to prove that the phofphoric and ba- it K phof- racic acids are the lame. But their experiments mere' J. oncaui. jy o^j^^ (y,j[ thefe acids refemble one another in feveral particulars ; and though they add confiderably to our knowledge of the properties of the phofphoric acid, they are quite inadequate to eflablifh the principle which thefe chemifts had in view ; fince it Is not fufficient to prove the identity of the two acids, to flicw us a refem- blance in a few particulars, while they differ in many others. Boracic acid mull therefore be confidered as a diftinft fubftance, the component parts of which are en- tirely unknown. The eafiell method of procuring boracic acid is the following one : Diffolve borax in hot water, and filter the folution; then add fulphuric acid, by little and little, till the liquor be rather more than faturated. Lav it afide to cool, and a great number of fniall, (hining, la- minated cryitals will form. Theie are the boracic acid. They are to be walhed with cold water, and drained upon brown paper. This acid has a fourifli tafle at firft, then makes a bittevilli cooling impreffion, and at laft leaves an agree- able fweetnefs. Its cry dais have fome refemblance to Ipermaceti, and it has the fame kind of feel. It changes vegetable blues to red ; it has no fmell ; but when fulphuric acid is poured on it, a tranfient odour of muflc is produced *. The air produces no DcSahSi- change on It. " ' ' ' ' According to Rcufs, it is foluble In 10 parts of cold water, eight parts of warm water, and 2,5 of boiling water. According to Wenzel, 960 grains of boiling wa- ter dilTclve 434 of this acid. According to Morveau, one pound of boiling water dilTolves only ll- {or common air. Bergman left a bottle of it uncorked, and found that in a few days it contained nothing but common air. Common air, indeed, has fo ftrong an af- finity for this gas, that it attrails it from water, as Mr Welter has obferved J. SupPL. Vol. I. Part I. 460 Its proper- ties, \ Bergman^ 1.9. I Uid. § IM. fins Jour- nal, i. 440 X Ann. (i^ Grim. iii. JIJ. It is abfurbcd by red hot charcoal, as Moroizo and Acctou» La Metherie have ihevvn. , ^''^' . It is capable of combining with alkalies, alkaline ,(,, earths, and alumina, and feveral metallic oxides, and ofCoin- fiiiming compounds known by the ndmu of carlionats.\"^^"<^i It has no affinity for jargonia, according to Klapioth •; * Jmrn. combined, nor their proportions, have been accurately afcertained. " 463 Acetous acid, as commonly prepared, is very fluid, Lowitz't has a pleafant fmell, and an acid talle. ' It reddens ve- ",'«'';"<* "'' 11 1 T 1 • ii • ■ ■ ]• ■ L obtaining gctable colours. In this ftate it is mixed vi'itti a gfeat ^j.^ ^^^^ proportion of water ; but Mr Lowiiz of Peterfburg has tons acid, difcovered that it may be obtained in a folid cryltalli- zed form. Of this curious and inftruftive procefs we fhall tranfcrlbe his own account ||. 1| Crtll't " I have long been accullomed (fays he) to prepare J''""'"'''' concentrated vinegar by congelation in the following'' "'' n. ''^' manner : I freeze a whole barrel of vinegar as much as poffible, then dillil the remaining unfiozen vinegar in a water-bath ; by which means I at firft efpecially coUeft the fpirituous ethereal part ; the vinegar, which next comes over, I freeze again as much as poffible, and af- terwards purify it, by difb'lliiig it again with three or four pounds of charcoal powder. Thus I never fail to get a very pure, fwect-imelling, highly concentrated vi- negar ; the agreeable odour of svhich, however, may be S s ftill (i) Count MufPin-Pufchin having boiled a folution of carbonat of potafs on purified phofphorus, obtained carbon. This he coniidered as an inftance of the decompofition of carbonic acid, and as a confirmation of the experiments rchrted in the text. See Hnn. de Chim. xxv. 105. (k) At lead near the furface of the earth. Lamanon, Mongez, and the other unfortunate philofophcis who accompanied La Peroufe in his lad voyage, have rendered t not improbable ihat at great heights the quantity of this gas is much fmaller. They could detedl none in the atmofphere at the furamit of the Peak of Teneriffe. See Lamanon' s Memoir at the end of La Peroufi^t Voyage, 322 Acetous Acid. G H E M I ftill improved by the addition of a proper quantity of the ethereal h'quor collefttd it the beginning of the firft dif- tillation, but which mult be previoufly dephlegmated by two or three reftificalions. " After the diftillatlon in the water-bath was over, that no vinegar might be loft, I ufed to move the retort, with the charcoal powder whicli remained in it, to a fandbatli ; and thus I obtained, by means of a ftrong fire, a few ounces more of a remarkably concentrated vinegar, which was of a yellow colour. " Having coUefted about ten ounces of this concen- trated vinegar, I expofed it lail winter in the month of ^December to a cold equal to — 2 2^; in which fituation it {hot into cryftals from every part. I let what re- mained fluid drop away from the cryftals into a bafon placed underneath, lirft in the cold air, and afterwards at the window within doors. There remained in the bottle fnow-white finely foliated cryftals, clofcly accu- mulated one upon the other, and which I at firll took to be nothing but ice : on placing them upon the warm flove, they dilTolvcd into a fluid which was perfeftly as limpid as water, had an uncommonly ftrong, highly pun- gent, and almoft fuffucating acetous fmell, and in the temperature of — JV immediately congealed into a fo- lid white cryftallized mafs, refembling camphor. " After I had obferved that vinegar in this ftate is of fuch an extraordinary ftrength and purity as to he in its higheft degree of perfeiStion, I took aO poffible pains to find out a method of obtaining all the acetous acid in the ftate of glacial vinegar. " To avoid circumlocution, I (hall denote the ftrength of each fort of vinegar, which it was neceflary for me to know in my experiments, by degrees, which I afcer- tain in the following manner : viz. to one drachm of vinegar I add, drop by drop, a clear 'Solution of equal parts of carbonat of potafs and water, till all at once a cluudinefs or precipitation appears. Although, on the appearance of this fign, the acid is already fuperfatu- rated with the alkali, yet it feems to me to be a more accurate left for afcertaining its ftrength than the cefla- tion of efFcrvcfcence ; for as the point of faturation ap- proaches, the efl"ervefcence becomes fo imperceptible, that it is alinoft impoflible to determine with precifion when it is really at an end. Now, every five drops of the alkaline folution, which I find it neceffary to add to the vinegar till the precipitation takes place, I reckon as one degree. Thus, for example, if a determinate quantity of vinegar requires 25 drops for that cffeft, I denote its ftrength by five degrees. This is about the ftrength of good dillilled vinegar. •' 1 call that vinegar which, in confequence of Its concentration, is capable of cryftallizing in a great de- gree of cold, cryjlalitxabh "vinegar ; the cryftals of vine- gar, feparatcd after the cryftallization is completed from the remaining fluid portion, I czW glacial vinegar ; and, laftly, to the fluid refiduum I give the name of mother- ky of vinegar. " From a great number of experiments, I have found that vinegar mull have at leaft 24 degrees of concentra- tion before it can be brought to cryftallize by expofure to the mod intenfe cokL Vinegar muft be of the llrength ef 42 degrees at leaft, in order to become glacial vine- gar ; iiiz. in this ftate of concentration it has the pro- perty of cryftallizing in a degree of cold not exceeding that iu which water begins to freeze. S T R y. Part ir. " I have found that charcoal, on being diftilled with vinegar in a water bath, poflcifes the fnigular and hi- therto unknown property of imbibing a certain quan- tity of the acetous acid in a very concentrated ftate, and of retaining it fo ftrongly, that the acid cannot be fe- parated from it again but by the application of a con- iiderably greater degree of heat than that of boiiinj; water. Upon this circumftance is founded the new method which I have difcovered of concentrating vine- gar, fo as to obtain all its acid in the pureft ftate, viz. that of a glacial vinegar. " Let a barrel of vinegar be concentrated by freezing in the manner above defcribed, and let the concentrated vinegar thus obtained, free from all inflammable or fpi- rituous parts, be put into two retorts: Add to each of them five pounds of good charcoal reduced to a fine powder, and fubjciSt them to dillillation in a water-bath. When no more drops of vinegar come over, put the diftilled liquor into two frefh retorts ; and after adding five pounds of charcoal powder to each, proceed as be- fore to the diftillation in a water-bath. In the mean while, the two firft retorts are to be placed in a fand- bath,, that, by means of a brifl< fire, the cryftallizable vinegar, which is retained in the apparently dry char- coal powder, may be expelled from it. The heat muft be ftrong enough to make the drops follow one another every two feconds ; and when, in this degree of heat, 20 feconds intervene between each drop, the vinegar which has been collefted muft be removed ; for what follows is hardly any thing elfe but mere water. In this manner about fix ounces and a half of cryftallizable vinegar, which is generally of the ftrength of between 36 and 40 degrees, may be collefted from each retort. As foon as the diftillation by the water-bath in the two retorts is over, the diftilled liquor is to be poured back again into the firft retorts upon the charcoal powder,- which remauis in them, and which has been already ufed ; and from each of thefe retorts the remaining cryftallizable vinegar (which generally amounts to as much as the firft quantity) is to be abftrafted by diftiU lation in a fand-bath. Thefe operations may be alter- nately repeated till all the acid of the vinegar which had been concentrated by freezing is converted into cryftallizable vinegar ; or until the diftilled liquor, con- ftantly becoming weaker and weaker at every repeti- tion of the diftillation, comes over at length in the ftate of mere water, which, with the above mentioned quan- tity of charcoal powder, generally happens at the fourth cr fifth diftillation. Now, in order to obtain the great- eft part of the pure acid contained in the cryftallizable vinegar in the form of glacial vinegar, it muft be fet to cryftallize in a great degree of cold ; and the mother- ley muft be afterwards thorotighly drained from the gla- cial vinegar, by letting it drop from the cryftals, firft in the cold, and then in the room before the window. The mother-ley may be rendered further cryftallizable by diftilling it with a little charcoal powder ; the weak- er part, which comes over firft, being put afide. But if a perfon wiihes to keep the cryftallizable vinegar for other purpofcs, and without feparating any glacial vine- gar from it, he muft diftil the whole of it again with charcoal powder in a fand-bath. " I have found by accurate experiments, that, by means of this curious procefs, ten pounds of vinegar^ concentrated by freezing to the 90th degree, may be made. Acetous Acid. Part II. Ac^ruu- Acid. CHEMISTRY. 464 A^ion of acetou' a- cid on o- ther bo- dies. 465 Its aftini. li£3. made to yield 38 ounces of ciTflallizabk vinegar, from which 20 ounces of ghicial vinegar may be olnaincd. " What conllitutes the cxtclleiice of this method is, that the conceiitraiiou and puiilication are effcCltd by one and the fame medium, viz. the cliarcoal powder; in confequence of which, both intentions are lulSUed at the fame time. " Lad year, after muc-h reflexion, I was fo happy as to find out another very efFertual method of fepaiating the acetous acid from the other lubftances combined with it, fo as to obtain it at once in the ilate of a gla- cial vinegar of the grcatefl pofTible llrength. The fe- parating medium which I thought of is fulphat of pot- afs fuperfaturated with iulphuric acid ; a fait in which, conformably to my purpole, the fulphuric acid exills in a perfeftly dry and dcplilegmatcd ftate. " By means of this fait a highly concentrated glacial vinegar may be obtained in the following manner : " Let three parts of acetated foda, prepared with vi- negar diftilled over charcoal, and evaporated to perfeft drynefs, be melted in a ftrong heat ; then pour it out, and rub it to a very fine powder. Mix this powder very accurately with eight parts of fuperfaturated ful- phat of potafs that has been previoufly well dried, and in like manner reduced to a fine powder; put the whole into a retort, and diftil with a gentle heat, in fuch man- ner that, along with the drops, fome vapours alio may be perceived to come out of the neck of the retort ; but by no means fo that the receiver fliall be filled with thcfc vapours. Notwithftanding the moderate heat, the vinegar conies over very fall, and the quantity of gla- cial vinegar, of the ftrength of 54 degrees, which is thus obtained, amounts to nearly two parts." Acetous acid is capable ot oxidating iron, zinc, lead, nickel, tin, copper. It does not aft upon gold, filver, platinum, mercury, bifmuth, cobalt, antimony, arfenic. It combines with alkalies, alkaline earths, and alumi- na, and metallic oxides, and forms compounds known by the name of acetltes. Its affinities are as follows : Barytcs, Potafs, Soda, Strontitcs ? Lime, Magnefia, Ammonia, Oxide of zinc, -^— — manganefe, Alumina *, Jargonia f ? iron, lead, tin, cobalt, copper, nickel, arfenic, bifmuth, mercury, antimony, filver, gold, platinum. ■iECT. Watw, Alcohol, XII. Of Acetic Acid. Accric Aci.l If ncctite of copper be diftilled, an acid comes over of a more pungent tmell than acetous acid, capable of cryilallizing, and having a ftrojiger afiinity for otl.er bo- dies than acetous acid. It is called acelic acid, and is fuppofed to contain a larger proportion of oxygen than acetous acid. This additional dofe it is fuppijfed to re- ceive from the oxide of copper, which during the pro- cefs is reduced to the metallic ilate. It can hardly be doubted that the glacial vinegar of Lowitz, defcribed in the preceding fedion, is really acetic acid, though it would perhaps be difficult to explain its formation. Il» affinities are the fame with thofe of the acetous acid. Sect. Xin. 0/ Oxalic MJ. Sugar, a well-known fubftance extrafted from the fngar-cane, appears to have been ufed in the Eaft at a very early period ; but it made its way weftward very Howly. As a medicine, it is mentioned by Diofcorides ; but it was not in common ule in Europe till after the 14th century. It has been proved that fugar is compofed of oxygen, Ccmvofi. carbon, and hydrogen. Lavoifier concluded, from a longtion of fu- feries of delicate experiments, that it confills of 8 parts g'>r. of hydrogi;n, 64 of oxygen, and 28 of carbon. , From fugar, by a particular procefs, an acid has been Dn^overy obtained called oxu/ic acid, becaufe it exifts ready form of oxalic ed, as Scheele has proved, in the oxalis acelofella, oratid. wood forrel. At firlt, however, it was called t!ie acid oj fugar, or the ftccharinc acid, i\.s the earlitll and bell account of the oxalic acid was publiflied by Bergman, he was for a long time reckoned the difcoverer of it ; but Mr Ehrhart, one of Scheele's intimate friends, informs us, that the world is indebted for its knowledge of this acid to that ilhiftrious chemid*, and Hermftadt and WeJlrum affign the dif- • Ehvart't covcry to the fame author f. The affertions of thefc -Vi,"i'« gentlemen, who bad the beft opportunity of obtaining/'*'' '^^'"*'" accurate information, are certainly fufficient to ellabiidi p^'"; '^^^' the faft, that Scheele was the real difcoverer of oxalic p. 54. acid. t keir's Bergman gives us the following procefs for obtaining •'■'"'"""'O'- this acid. " Put one ounce of white fugar powdered ,vie1hod of into a tubulated retort, with three ounces of llrong ni- procuring trie acid, the fpecific gravity of which is to that ofit. water as ,561. When the folution is over, during which many fumes of the nitrous acid efcape, let a re- ceiver be fitted, and the liquor made to boil, by which abundance of nitrous gas is expelled. W^hen the liquor in the retort acquires a nddilh brown colour, add three ounces more of niiric acid, and continue the boiling till the fumes ceafe, and the colour of the liquor va- niflies. Then let the contents of the retort be emp- tied into a wide vcffcl ; ami upon cooling, a cryllallj. zation will take place of flender, quadrilateral prifmj, which are often aflixcd to each otiicr at an angle of 450. Thcfe cryitals, collected and dried on blottnig paper, will be found to weigh i| dr. 19 gr. By bo3ing the remaining lixivium with two ounces of nitric acid in the retort, till the red fumes almoil difappear, and by repeating the cryflalirzation as before, -J dr. i^ gr. of folid acid will be obtained. If the procefs be repeated S s 2 once 3H CHEMISTRY. Oxalic Acid. * Bergman. t HermJIaJt. 469 Its proper- ties. t Bergman ^ II Hid. § ttid^ 1 Uid. » Jiid. f Encyc. MetboJ art. .4«J; Saccharin , once more upon the refiJiium, which has now a glutL- nous conlillence, witli the AicccfTive additions of fmall quantities of nitric acid, amounting in all to two oun- ces, a faline brown deliqnelcent inafs will be formed, weighing half a dram, of which about a half will be lofl by a farther purification. The cryilals obtained thus at different times may be purified b-- folution and ci-)ftHllization, and by digciting the lad lixivium with fome nitric acid, and evaporation with the heat of the fun." By the fame procefs Bergman obtained It from gum arabic, alcohol, and honey : Schecle, Hermftadt, Wef- trum, Hoffman, &c. from a great variety of other ve- getable produftions ; and BerthoUet from a great num- ber of animal fubilances. It is of great confeqiicnce not to ufe too much nitric acid, otherwife the quantity of oxalic acid will be dimi- nifhed ; and if a very great quantity of nitric acid be ufed, no oxalic acid will be obtained at all *. On the contrary, if too fmall a quantity of nitric acid be ufed, the acid obtained will not be the o.\alic, but the tarta- rous-|-. We think we haveobferved, that a confiderably larger proportion of oxalic acid may be obtained by pouring nitric acid on fugar, and allowing thefe fubilan- ces to aft upon each other while cold. When the pro- cefs is condufted in that manner, hardly any thing fe- parates but nitrous gas. Oxalic acid is capable of cryflallizatlon, or rather it is generally obtained in that ftate. Its cryilals are qua- drilateral prifms, the ends of which often terminate in ridges J. They are foluble in their own weight of boiling wa- ter : water at the temperature of 65,7" diffolves half its weight of them. The fpecilic gravity of the folution is 1,0593 II • ^"'^ hundred parts of boiling alcohol dlf- folve 56 parts of thefe cryilals ; but at a mean tempe- rature only 40 parts §. They are not eafily fuluble In ether. Fixed and volatile oils diffolve them, and they may be again obtained by gentle evaporation. Too vio- lent a heat would fublime the acid itfclf. Oxalic acid has a very acrid taile when it Is concen- trated, but a very agreeable acid taile when fufficlently diluted with water <[[. It changes all vegetable blues except Indigo to a red. One grain of cryflaUized acid, djffolved in 1923 grains of water, reddens the blue paper with which fugar loaves are wrapt: one grain of it, diffulved in 3600 grains of water, reddens paper ftained with turnfole*. Accord- ing to Morveau, one part of the cryftallized acid is fufficlent to communicate a fenfible acidity to 2633 parts of water -f-. Its fixity Is fuch, that none of It is fublimed when water containing it In folution is railed to the boiling temperature. When this crydallized acid is expofed to heat in an open veffel, there arifes a fmoke from It, which affefts difagreeably the nofe and lungs. The refiduuni is a powder of a much whiter colour than the acid had been. By this procefs it lofes tV^^^ °f ''^ weight ; but foori recovers them again on expofure to the air. When di- ftilled, it firft lofes its water of cryftalllzation, then li. quifies and becjmes brown; a little phlegm paffes over, a white faline cruil fublimes, fome part of which paffes into the receiver ; but the greateft part of the acid is deftroyed, leaving in the retort a mafs -j-gth of the whole, Part If, which has an empyreumatic fmell, blackens fulphuric Tartarouj acid, renders nitric acid yellow, and diffolves in muria- •^' ^''*- tic acid without alteration. That part of the acid which * fublimes is unaltered. When this acid is dlilllled a fe- cond time, it gives out a white fmoke, which, conden- fmg in the receiver, produces a colourltls uncryftalli- zable acid, and a dark coloured matter remains behind*. * Bergman. During all this diftillation a vail quantity of elalllc va- pour makes its efcape. From 279 grains of oxalic acid, Bergman obtained 109 cubic inches of gas, half of which was carbonic acid and half hydrogen. Fontana from an ounce of it obtained 4^0 cubic inches of gas, one-third of which was carbonic acid, the reil hydro- gen. From thefe fadls, it is evident that oxalic acid Is compofed of oxygen, hydrogen, and carbon ; but the proportions are ftill unknown. When nitric acid is frequently dlilllled off oxalic acid, acetous acid is produced f. The fulphuric acid, when f Wejtrum. concentrated, feems to produce the fame effeft. Mu- riatic and acetous acids diffolve oxalic acid, but without altering It J. } Bergt,tan, Oxalic acid is capable of oxidating lead, copper, iron, 47° tin, biimuth, nickel, cobalt, zmc, manganele. ^^ other It docs not att upon gold, tilver, platinum, mercury, bodies, arfenic ? Oxalic acid combines with alkalies, alkaline earths, and alumina, and metallic oxides, and forms falts known by the name of oxalats. Its affinities, according to Bergman, are as follows: j,sa^' •_ Lime, Barytes, Strontites J, Magnefla, Potafs, Soda, Ammonia, Alumina, Jargonla || ? Metallic oxides as \n fulphuric acid, Water, Alcohol. Sect. XIV. 0/ Tartarous JchL § DrHcp?, Tranf, Edw. ll emcjue.tr.^ Ann. de Clim, xxii. »o3. 472 Tartar, or cream of tartar as It is commonly called oifcovery vi'hen pure, has occupied the attention of chemifts for of tartarouj feveral centuries. Duhamel and Groffc, and after thcm^^'*^* Margraf and Rouelle the Younger, proved that It was compofed of an acid united to potafs: but Scheele was the firll who obtained this acid in a feparate ftate. He communicated his procefs for obtaining it to Retzlus, who publilhed it in the Stockholm '1 ranfaftlons for 1770. It confiiled in boiling tartar with lime, and in decompofing the tartrite of lime thus formed by means of lulphuric acid. This acid, by a gentle evaporation, yields cryftals fo u, proper. Irregular In their figure, that every chcmift who has ties, treated of this fubjedl has given a different defcrlptlon * *'^.f«""'» of them. According to Bergman, they generally con.'"y^°^' fift of divaricating lamellae * ; according to Van Pack- £iT,„f, acidi en, they affume ofteneft the form of long pointed T;r/ari. prifms f ; Spielman and Corvinus J obtained them in -' '^nateSa groups, fome of them lance-fliaped, others needle-form- /p"''''"'''" ed, others pyramidal. Morveau obtained them needle- ^/,,i,y^ form §. They do not experience any change in the air; CA/». i. heat 3^3- Fart Tr Citric Ac ill. ihiJ lil'.d ii. 4<'5 3Iid Cctvt- nils, ii>:J, ^ hcii'ifaJt and «•idijb behind pure malic acid ]|. r'-WA '^'''^ ^'■'"^ '** contained in the berries of the ^ariifw nils for ' •vulgaris, the famliucus nigra, the primus fpinofa, the ybr- bus aucuparia, and the prunus domejiica^. If nitric acid be diftilled with an equal quantity of fugar, till the mixture affumes a brown colour (which is a fii^n that all the nitric acid has been abftrafled from it), this fubftance will be found of an acid tatte ; and after all the oxalic acid which may have been formed is feparated by lime-water, there remains another acid, which may be obtained by the following procefs : Sa- turate it with lime, and filter the folution ; then pour upon it a quantity ot alcohol, and a coagulation takes place. This coagulum is the acid combined with lime. Separate it by filtration, and edulcorate it with frefli al- cohol ; then diffolve it in diftilled water, and pour in acetite of lead till no more precipitation enfues. The precipitate is the acid combined with lead, from which it may be fepaiated by diluted fulphuric acid. It pof- fefTes all the properties of malic acid *. This acid, therefore, may be obtained from fugar ; and it may be converted into oxalic acid, by diftiUing off it the prp- f Hfrw/aA.per quantity of nitric acid f. fhyf. chtm. This acid bears a ftrong refemblance to the citric, but differs from it in the following particulars: 1. The citric acid (hoots into fine cryftals, but this aold does not eryftalllze. 2. The fait formed from the citric acid with lime Is almoft Infoluble in boiUng water; whereas the fait made with malic acid and the fame bafis Is readily foluble by boiling water. 3. Malic acid precipitates mercury, lead, and filver, from the nitrous acid, and alfo the folution of gold when * Hid. 4S2 Its proper- ties. diluted v.ith water ; whereas citric acid docs not alter any of tlufc folutions. 3. Malic acid feenis to have a lefs aflinity than citric acid for lime ; lor wlien a folution of lime in the for- mer acid is boiled one minute with a fait formed from volatile alkali and citric acid, a decompofitlon takes place, and the latter acid combines with the lime and is precipitated. The malic acid combines with alkalies, alkaline earths, and alumina, and metallic oxides, and forms falls known by the name of mnlats. Its ailliilties have not yet been afcertained. Sect. XVII. Of Laaic Acid. If milk be kept for fome time It becomes four. The acid wliich then appears in it was firft examined by Schcele, and found by him to have peculiar properties. It is called laQic acid. In the whey of milk this acid is mixed with a little curd, fome phofphat of lime, fugar of milk, and mucilage. All thefe muft be feparated before the acid can be examined. Schecle accomplilhed this by the following procefs : Evaporate a quantity of four whey to an eighth part, and then filtrate It: this feparates the cheeiy part. Sa- turate the liquid with lime-water, and the phofphat of lime precipitates. Filtrate again, and dilute the liquid with three times Its own bulk of water; then let fall In- to It oxalic acid, drop by drop, to precipitate the lime which it has diffolved from the lime-water : then add a very fmall quantity of lime-water, to fee whether too much oxalic acid has been added. If there has, oxalat of lime Immediately precipitates. Evaporate the folu- tion to the coniiftence ot iioney, pour In a fufficient quantity of alcohol, and filtrate again ; the acid pafies through diffolved in the alcohol, but the fugar of milk and every other fubftance remains behind. Add to the folution a fmall quantity of water, and diftll with a fmall heat, the alcohol paffes over, and leaves behind the ladlic acid diffolved in water *. This acid Is Incapable of cryftalllzing : when evapo- rated to drynefs, It deliquefccs again in the air f. When diftilled, water comes over firft, then a weak acid refembling the tartarous, then an enipyreumatic oil mixed with more of the fame acid, and laftly carbonic acid and hydrogen gas — there remains behind a fmall quantity of coal f . The combinations which this acid forms with alka- lies, earths, and metallic oxides, are called laHats. Its affinities, according to Bergman, are as follows : Barytes, Potafs, Soda, ^ Ammonia, Lime, Magnefia, Alumina, Jargonia J ? Metallic oxides as in fulphuric acid. Water, Alcohol. Sect. XVIII. Of Sacchokaic Acid. La(5lic Acid. 483 'te comb;, nations, 484 Method •! o!ua'ninjj iai5iic acid, * Srhctli, St ci/jolm Trali/.ljSo. t 'i!d. 485 lt= [Topei" ties, t 'liJ. 4S5 Ccmbina. tions, 487 And aSu, tiss. § KauguttlK jinn, de Chtm. xxii. 208. 488 If a quantity of frefh whey of milk be filtrated, and Sugar der which he obtained was nothing elfe than oxalat ofcsiftcce. lime with excels of acid, as indeed Scheele himfelf did at firft. After he became acquainted with Schcelc's conclufions, he publiflied a paper in defence of his own opinion ; but his prools are very far from eilablilhiug it, or even rendering its truth probable. He acknowledges himfelf, that he has not been able to decompofe this fup- pofed fait : he allows that it polfefres jiroperties dillinft from the oxalic acid ; but he afcribes this difference to th£ lime which it contains ; yet all the lime which he- could difcover in 240 grains of this fait was only 20 grains ; and if the alkali which he employed was a car- bonat (as it probably was), thefe 20 muft be reduced to n. Now Morveau has ihewn, that oxalic acid, con- taining the fame quantity of lime, exhibits very different properties. Befides, this acid, whatever it is when uni- ted with lime, is feparated by the oxalic, and muil therefore be different from it, as it would be abfurd to fuppofe that an acid could difplace itfelf |:. The fac- t Metvcm, choladlic acid mull therefore be confidered as a dillincl -^"'.v- acid, as it poflefTes peculiar properties. ^ '' ° ' '• Its compounds with alkalies, earths, and metallic ^g~ oxides, are denominated _/i;«/;o/j/x. Its com- Its affinities, according to Bergman, are as follows : P'^nd* ^r.d Lime, Barytes,. Magnefia, Potafs, Soda, Ammonia, Alumina, JargoniaJ? ^fauyelin,. Metallic oxides as in fu'piuric aciJ,'^""''' Water, Alcohol. * Chim. xxii»> 20 8. 493 Sect. XIX. Of Gallic /Icid. There is an excrefccnoe, known by the name of wr/Z-Nut-'alW^. gall, which grows on fome fpecles of oaks. This furv. Ibance contains a peculiar acid, called from thatcircum- {\.Sincit gallic acid, the properties of which were firlt ex- amined with attention by. the commlflioners of the aca- demy of Dijon ;. and the refult of their experiments was publiHied in 1777, in the third volume of their Ele- ments of Chemlllry. In thefe experiments, hou-ever, they employed the infufion of galls, In which the acid is combined with the tanning principle (m). It was referved for Scheele to obtain it in a itate of purity. He (m) a fubftance lately difcovered by French chemlfts, which exifts alfo in oakbnrk, and aveiy other body which may be fubilituted for that bark in the operation of tanning. It reTembles the relins in many projjertics ;; but Its dillingulfhing property is tb^t of forming with glue a compound Infoluble In water. When a little of< tfee decoftlon of glue is dropped into an Infufion of nut-galls, a white curdy precipitate is inflantly feen : This; is the tanning principle combined with glue. The name tanning principle has been applied to it, becaufe tamiingi eonfills in corabinipg this principle with^X-inf, by which they are coriverted into leather. tid. 328 C H F. M Gallic He oSfcrvcJ, in an I'nfuilon of galls made with cold , ^" ' water, a fcdimcnt, which proved on examination to ^g. have a cryllalline form and an acid tafte. By letting Difcovery an infufiun of galls remain a long time expofed to the ot gallic a- air, and removing now and then the mouldy (1-cin whith formed on Its fnrface, a large quantity of this lediment was obtained ; which being edulcorated with cold wa- ter, rediflolved in hotw;itcr, filtrated, and evaporated very »StoM(ilm (]o„-ly^ yielded an acid fait in cryftals as fine as fand*. itS6 There is a (hortcr method of obtaining this acid in 4^5 a ftiU purer ftate than Scheelc obtained it. Method of Poui" fulphuric ether on a quantity of powdered galls, obtaining g^j ^Uow it to remain a few hours ; by which time it becomes coloured. Put this tinfture into a retort, and dlPuil off the ether with a fmall heat. The rtfiduum poiTcffes the colour and brittlenefs of a refin, and has all the charafters of Rouelle's refiduous-extraft ; it does not attraft moillure from the atmofphere. Diffblve it in its own weight of water, and add fulphuric acid, drop by drop, till the liquor has become of a manifeilly acid taile. It caufes a white precipitate, which be- comes coloured, and is immediately redilTolved. At the €nd of fome hours a rcfinous matter will have precipi- tated. Decant off the fluid, dilute it with half its weight of water, filtrate ^ii.i evaporate it to |ths in a moderate heat ; add pure barytes till the liquor is no longer ca- pable of decompofmg muviat of harytes ; tlien filtrate it again ; and on evaporation in a moderate heat fmall white prifmatic cryftals of gallic acid are formed on the Di-'e 7o'J' '''^" "f '■'"= ^"^''^ t • deFb/r.'"'' It appe'iirs from the experiments of Dcyeux, that the Dec.'i-Qt. fubilance extrafted from nut-galls by ether does not dif- t y^rn.iie^ fer much from the extraiSl by water J. Probably, then, the only reafon fur employing ether is the imall heat necelFary for evaporating it. There is ftill another method of obtaining this acid. Diftil nut-galls In a ftrong heat, a wliite fubftance fu- blimes, which cryftallizes in the form of needles : This is gallic acid. If the cryftals are impure, they may be purified by a feeond fabiimation : but the heat niuft; not be too violent, otherwife the cryftals will melt in. to a brown mafs §. This procefs was difcovered by Scheele. But the moft elegant method of obtaining gallic acid is that of Mr Prouil. When a folution of muriat of tin is poured into an infufion of nut-galls, a copious yellow precipitate is inftantly formed, confifting of Xhe tanning principle, combined with the oxide of tin. After di- luting the liquid with a fufficient quantity of water to feparate any portion of this precipitate which the acids might hold in folution, the precipitate Is to be fepara- ted by filtration. The liquid contains gallic acid, mu- riatic acid, and muriat of tin. To feparate the tin, a quantity of fulphurated hydrogen gas is to be mixed with the liquid. Sulphuret of cxide ot tin is precipi- tated under the form of a brown powder. The liquid 18 then to be expofed for fome days to the light, cover- ed with paper, till the fuperfluous fulphurated hydrogen gas exhales. After this, it is to be evaporated to the proper degree of concentration, and put by to cool. Cryftals of gallic acid are depofiled. Thefe are to be feparated by filtration, and wafhed with a little cold water. The evaporation of the reft of the liquid is to 5 HiJ. Lg repeated till all the eallie acid is obtained from it'll. Cfjisi, xvii. 8. § nij. 496 Prouft's method. I S T R Y. Part 11. The gallic acid thus obtaired has a very acid tafte, Gallic and reddens vegetable colours. It is foluble In i|- parts ^' - ''^' of boiling water, and in 12 parts of water at the tem- perature of the atmofphere. Alcohol difTolves one-It« (ironcr- fourth of its weight of this acid at the temperature ofii-i. the atmofphere. When boiling hot it diflblvea a quan- tity equal to its own weight. When placed upon burning coals, gallic acid takes fire, and at the fame time diffufes a very ftrong odour, which has fomething aromatic in it. When ftrongly heated, it melts, bolls, becomes black, isdiflipated, and leaves a quantity of charcoal behind it. When dillil- led, a quantity of oxygen g is is difergaged, an acid li- quor is found in the receiver, with fome gallic acid not decompofed, and there remains In the retort a quantity of carbon. If what has paiTed into the receiver be again dlftllled, more oxygen gas is obtained, fome gallic acid ftill fublimes, and a quantity of carbon remains in the retort. By repeated diftillations the whole of the acid may be decomjiofed. This decompofition may be more eafily accomplKhed by diftlUIng repeatedly a folu- Ji tlon of gallic acid In water. The produfts are oxygen 9 gas, charcoal, and an acid liquor. 45S From thefe experiments, JMr Deyenx, who perform-''^ i:ompoG» ed them, has concluded, that gallic acid Is compofed of"°"' oxygen, and a much larger proportion of carbon than enters into the compofition of carbonic acid. But this conclufion is not warranted by the analyfis ; for Mr Deyeux did not find that the quantity of oxygen gas and carbon obtained was equal to that of the gallic acid decompofed :. and in the acid liquor which came over, there evidently exifted a quantity of water, which doubtlefs was formed during the diftillation. Scheele, by treating gallic acid with nitric acid in the ufual man- ner, converted It into oxalic acid. Now it Is certain that oxalic acid contains hydrogen as well as carbon. It cannot be doubted, then, that gallic acid is compo- fed of oxygen, hydrogen, and carbon, in proportions not yet alcertaiiied. But Mr Deyeux has proved, that the quantity of carbon is very great, compared with that of the hydrogen. Gallic acid combines with alkalies, earths, and me- tallic oxides, and forms compounds known by the name ol a allots. Its affinities have not yet teen determined; but oxide of iron ieems to have a ftronger affinity for it than for any other fubftance ; for gallic acid is capable of taking it from every other acid. In confequence of this pro- perty, the Infufion of galls is employed to deteA the prtfence of iron In any liquid. As foon as it Is poured in, it iron be prefent, a black or purple colour is pro- duced. 4Q9 Sect. XX. Of Benzoic act J. Benzoin or benjamin (as it is fometimes called) Is aB^,[^2(,i^, kind of refin brought from the Eaft Indies ; obtained, according to Dr Dryander, from the ftyrax benzoe, a tree which grows In the ifland of Sujtiatra This fub- ftance confifts partly of a peculiar acid, defcrlbed as long ago as i6c8 by Blalfe de Vigenere, in his Trea- tife on Fire and Salt, under the name oijloivers of ben- zoin, becaufe it was obtained by fubllniation. This acid, which is now called the benzoic acid, may be fu- blimcd from benzoin by heat ; or it may be obtained by j Scheele's p c\A. CHEMISTRY.' 329 It is obtained by the fullowiiig proccfs : Fill a retort Camphoric half way witli powdered amber, and cover the powder '^^'^- witli a quantity of dry faiid ; lute on a receiver, and ' diftil in a fand-batli without employing too much heat. Method of There palfes over lirft an inlipid phlej^in ; then a weak'ih'aining fulion of violets ; but it reddens that of turnfole, tfpe- acid, which, according to Scluele, is the acetous * ; then'"'''"'' Part ir. Succinic Seheele's proeefs, which has been defcribed in the ar- ^^ ''^ ^ticie Chemistry, Encycl. ' Benzoic acid has little or none of the peculiar odour Propertios which diilinguiflies benzoin. Its tafte is not acid, but of benzoic fweetilh, and very pungent*. It hardly affcfts the in- * °'JJ,y^"'cially if that infulion be hot f . Heat volatilizes this thuj. Cbim. acid, and makes it give out a ftrong odour, which ex- i. 44. cites coughing. When expofed to the heat of the + Licbim- blow-pipe in a fiK-er fpoon, it melts, becomes as fluid ■r""' as water, and evaporates without taking fire. It only burns when in contact with flame, and then it leaves no rellJuum behind. When thrown upon burning coals, it rifes in a white fnioke. When allowed to cool alter being melted, it hardens, and a radiated crull forms on its furfacej. It fuffers no other alteration In the air than lofing the little of the odour of benzoin which remained to Cold water dlfTolves no fenfible quantity of it ; but it is foluble enough in hot water : 480 grains of boil- ing water diflblve 20 grains of it ; 19 of thefe are de- polited, when the water cools, in long, flender, flat, fea- ther-like cryllals ||. Concentrated fulphuric acid diflolves it without heat or any other change except becoming fomewhat brown: when water is poured into the folution, the benzoic acid feparates and coagulates on the furface without any al- teration ^. Nitric acid prefents precifely the fame phe- nomena, and alfo the fulphurous and nitrous acids. Nei- ther the muriatic, the oxy-muriatic, nor the phofphoric acids diflblve it. The acetous, formic, and febacic acidj, when hot, diflblve it precifely as water does ; but it cryttallizes again when thefe acids cool *. Alcohol diflolves it copioufly, and lets it fall on the addition ot water -j-. Little is known refpeAing its bafe. It combines with alkalies, eartlis, and metallic oxides, nations and and forms falts known by the name of ieiizoiits. Its aiiinnies, from the experiments ot Iromniidort, appear to be as follows : White oxide of arfenic, Potafs, Soda, Ammonia, Barytes, Lime, Magnefia, Alumina, Jargon ia:j: ? Water, Alcohol, Sect. XXI. 0/ Succinic /Icid. Amber is a well-known brown, tranfparent, inflam- mable body, pretty hard, and fufceptible of polifli, found at fome depth in the earth, and on the fea-coaft of feveral countries. It was in high eftimation among the ancients both as an ornament and a medicine. — When this fubftance is diftilled, a volatile fait is obtain- ed, which is mentioned by Agricola under the name of fait of amber ; but its nature was long unknown. Boyle was the firft; who difcovered that it was an acid J. From fuccinum, the Latin name of amber, this acid has recei- ved the appellation oifuccinic acid. SUPPL. Voi,. I. Part I, X IJtm. uu. II Lichtai- Jit'ln. \Id. m Id. 501 Irs n,m\- affinities. t Va:tque- /m, Ann. de Chim. xxii. 308. 501 Amber. $ "Boyle n~ bridged by SbazVf ill, 3h- the fuecinic acid attaches itfelf to the neck of the re-.w' tort ; and it tlie diltillation be contmued, there comes a-o/,, «, over at lall a thick brown oil, which has an acid talle. Scbegcr. Tiie fuecinic acid is at firll mixed with a quantity of oil. Perhaps the bell method of purifying it is that recommended by Pott, to diflblve it in hot water, and to put upon the filter a little cotton, previoufly moil- tcned with oil of amber ; this fubftance retains moft of the oil, and aflows the folution to pafs clear. The acid is then to be cryftallized by a gentle evapora- tion. And this procefs is to be repeated till the acid 504 be quite pure. The cryllals are white, fliining, and Its propcr- of a foliated triangular prifmatic form: they have an""^'i acid tafte, but are not corrofive : they redden tinfture of turnfole, but have little efft'dl on that of violets. They fjblime when expuled to a confiderable heat, but not at tiie heat of a water-bath. In a fand bath they melt, and then fublime and condenfe in the upper part of the veflTel ; but the coal which remains fliews that they are partly decompofed f . | p„ii. One part of this acid diifolves in 96 parts of water at the temperature of 50", according to Spielman J, in 24)/,^ Chem. parts at the temperature of 5 2", and in 2 parts ot water at j xii. the temperature of 21 a', according to Stockar de Neu- fornf; but the greatelt part cryftallizes as the water » 73« S»5«. cools. According to Roux, however, it ftill retains morco. of the acid than cold water is capable pf diflblviug ||. u Morveau 240 grains of boiling alcohol dilFolve i 77 ol tin's acid ; /''/i/. p. 72. but cryftals again flioot as the iolution cools ^. \ IVenzel. The combinations of this acid arc ciWiid fuccinats . 5'5 Its component parts are Hill unkiiov.u. Combma. T^ fj. . . • ,. - , f. ,, ■ tjon.s and Its ailiiatie.s, accordmg to Morveau, are as toUows i Barytcs, Lime, Potafs, Soda, Ammonia, Magnefia, Alumina, Jargonia * ? Metallic oxides as m fulphuric acid, Water, Alcohol. S E CT. XX II. Of Camphoric Acid. Camphor, is a well-known white cryftalline fubftance, Camphor, of a ftrong tafte and frnell, obtained from a fpecies of laurel in the Eaft Indies ; and Mr Prouft has fliewn that feveral volatile oils contain a confiderable quantity of it f . It is fo volatile, that it cannot be melted in f /fm. i Ann, Je Cbim. iUd. Its proper- tics. H KofegaT' Un. ^J.aCrangt. * Kofi:gir. tn. f bouillon La G range y jAan. ds Chim. iivii, 40. Total 7(^,427 Lofs 45,821 Carbonated hydrogen gas and carbonic acid were alfo formed *. The oil obtained has the following properties : It has a fharp cauftic talle, and leaves upon the tongue a fenfe of coldnefs. It has an aromatic odour, approaching to that of thyme or rofemary. Its colour is a golden yellow. When expofed to the air, it partly evaporates, and there remains a thick brown matter with a fharp bit- terifli tafte, which at laft alfo evaporates. With alkalies, it forms a foap, which poffeffes all the charafters of foaps made with volatile oils. Alcohol didblves it entirely ; and when water is add- ed to the folution it becomes milky, but no precipitate is produced \. Thefe properties fhew that this is a volatile oil, and confequently it is probable that camphor is compofed of volatile oil and carbon. Mr Kofegarten, by dirtilling nitric acid off camphor ei^ht times Tucceffively, obtained an acid in cryftalsj, to which the name of camphoric acid has been given. His experiments have been repeated by Mr Bouillon La Grange. He mixed together 122,284 parts of cam- phor with 4^59, 1 36 parts of nitric acid of the fpecific gravity 1,33, and diftilled them. Much nitrous and car- bonic acid gas were difengaged, and part of the cam- phor vyas fublimed ; but part was converted into an acid. He returned the fublimed camphor into the re- tort, poured on it the fame quantity of nitric acid as at firft, and diftilled again. This procefs he repeated till the whole camphor was acidified §. The quantity of camphoric acid obtained amounted to 53,498. The quantity of nitric acid was 21 14,538. Camphoric acid thus obtained is in fnow-white cry- ftals, of the form of patallelopipedons||. Thefe ci7llals efflorefce in the air^. Camphoric acid has a flightly acid bitter tafte, and fmell like that of fafFron. It reddens vegetable colours. It is foluble in 200 parts of cold water, according to -Kofegarten ; I'l 96 parts of water at the temperature of 60°, according to La Grange. Boiling water dif- folves Tifth of its weight *. According to Kofegarten, it is iufoluble in alcohol ; according to La Grange, alcoiiol dilfolves it, and when the folution is left in contadl with the air of the atmo- fphere, the acid cryflaliizes. It is not precipitated from its folution in alcohol by the addition of water f. When this acid is placed on ignited coals, it emits a denfe aromatic fume, and is entirely diflipated. By a gentler heat, it melts, and is fublimed. If it be put into a heat'Cd porcelain tube, and oxygen gas be patfed through it, the acid docs not undergo any change, but is fublimed. By mere dilHllation, it firft. melts and then fublimes ; by which procels its properties are in fome refpedt changed. It no longer reddens the tinfture of turnfole, but acquires a brilk aromatic fmell ; its tafte becomes lefs penetrating, and it is no longer foluble either in water or the fulphuric and muriatic acids. Heated ni- tric acid turns it yellow and dilfolves it. Alcohol like- wife diffolves it ; and if this folution be left in contaft with the air of the atmofphere, it cryftallizes. Camphoric acid docs not produce any change in ful- phur ; alcohol and the mineral acids totally dilfolve it ; and fo likewife do the volatile and the fat oils. Camphoric acid does not precipitate lime from lime- water. It produces no change on the folution of indi- go in fulphuric acid. jro It forms combinations with the alkalies, earths, and'tscombi- metallic oxides, which are called camphorats. nations and Its affinities, as far as afcertained by La Grange, are ^ as follows * Seci Lime, Potafs, Soda, Barytes, Ammonia, Alumina, Magnefia. XXIII. Ann. de Ciim.jixyil, II. 5'I Of Suberic Acid. Cork, a fubftance too well known to require any pif^^^gr- defcription, is the bark of a tree which bears the fameof fuberic name. By means of nitric acid, BrugnatcUi converted *cid. it into an acidf, which has been called the/uberic acid,f Cnll't from Suber, the Latin name of the cork-tree. Several ^^"iii/i, chemifts affirmed that this acid was the oxalic, becaufe 'V^?- it pofleffed feveral properties in common with it. Thefe aftertions induced Bouillon la Grange to undertake a fet of experiments on fuberic acid. Thefe experiments, which have been publiihed in the 2^d volume of the Annales de Chimie, completely cllablifh the peculiar na- ture of fuberic acid, by (hewing that it polfeffes proper- ties diff^erent from thofe of every otiier acid. To prepare it, a quantity of found cork grated down Method of fmall is to be put into a retort, fix times its weight of preparing nitric acid of the ipecific gravity 1,261 poured upon'"^- it, and the mixture diftilled by means of a gentle heat. Red vapours are immediately difcharged; the cork fwells up and becomes yellow, and as the diftillation advances, it finks to the bottom, and its furface remains frothy. If that froth does not form properly, it is a proof that fome part of the cork has efcaped the action ot the acid. In that cafe, after the diftillation is pretty far advanced,, the acid wliich has paffed into the receiver is to be poured back into the retort, and the diftillation conti- nued till no more red vapours can be perceived ; and then the retort is to be immediately taken out of the fand-bath, otherwife its contents would become black and adhere to it. While the matter contained in the retort is hot, it is to be poured into a glafs veftcl, pla- ced upon a faud-bath over a gentle fire, and coaftantly llirred with a glafs rod. By this means it becomes gradually Part ir. CHEMISTRY. Suberic gradually thick. As foon as ivhite vapours, exciting '^'^i '• a tickling in the throat, begin to difengagc thcmfelves, "~"^' the vcfTtl is removed from the bath, and the mafs con- tinually ftirred till it is almolt cold. By this means an orange-coloured mafs is obtained of the confidence of honey, of a ftrong and Iharp odour while hot, but having a peculiar aromatic fmell when cold. On this mafs twice its weight of boiling water is to be poured, and heat applied till it becomes liquid ; and then that part of it which is infoluble in water is to be feparated by tiltration (n). The filtered liquor be- comes muddy ; on cooling it depofites a powdery fedi- ment, and a thin pellicle forms on its furface. The f^- diment is to be feparated by filtration, and the liquor reduced to a dry mafs by evaporating in a gentle heat. This mafs is fuberlc add. It is ftiil a little coloured, owing to fome accidental mixture, from which it may be purified either by faturating it with potafs and pre- cipitating it by means of an acid, or by boiling it along with charcoal powder. Suberic acid thus obtained is not cryftallizable, but when precipitated from potafs by an acid, it affumes the form of a powder ; when obtained by evaporation it forms thin irregular pellicles. Its tafte is acid and flightly bitter ; and when diffol- ved in a fmall quantity of boiling water it adls upon the throat, and excites coughing. It reddens vegetable blues ; and when dropped into a folution of indigo in fulphuric acid {^liquid blue, as it is called in this country), it changes the colour of the folution, and renders it green. Water at the temperature of 60° or even 70* diflblves only part of its weight of fuberic acid, and if the Its proper- ties. ■57'6 acid be very pure, only -rjjth part : boiling water, oji the contrary, diffolves half its weight of it. When expofed to the air, it attrafts moifture, efpe- cially if it be impure. When expofed to the light of day, it becomes at lall brown ; and tliis effect, is produced much fooner by the dircA rays of the fun. When heated in a matrafs, the acid fublimes, and the infide ot the glafs is furroundcd with zones of different colours. If the fublimation he flopped at the proper time, the acid is obtained on the fides of the vefTel in fmall points formed of concentric circles. When ex- pofed to the heat of the blow-pipe on a fpoon of pla- tinum, it firft melts, then becomes pulverulent, and at lalt fublimes entirely with a fmell refembling that of fe- bacic acid (o). It is not altered by oxygen gas : — the other acids do not diflblve it completely. Alcohol developes an aro- matic odour, and an ether may be obtained by means of this acid. It converts the blue colour of nitrat Sf copper to a green ; the fulphat of copper alfo to a geen; green ful- phat of iron to a deep yellow ; and fulphat of zinc to a golden yellow (p). It has no adtion cither on platinum, gold, or nickel ; I's adion but it oxidates filver, mercury, copper, lead, tin, iron,"" "'*^^'' bifmuth, arfenic, cobalt, zinc, antimony, manganefc, and molybdenum. With alkalies, earths, and metallic oxides, it forms compounds known by the name oi fuberats. Its affinities are as follows (q^) : T t 2 Barytes 5'4 Itsallinicies, (n) When this fubftance is put into a matrafs, water poured on it, and heat applied, it melts ; and when the velfel Is taken from the fire and allowed to cool, one part of it, which is of the confiftence of wax, fwims on the furface of the water, and another part precipitates to the bottom of the vcffel, and afTumes the appearance of a whitifh magma. When this magma is feparated by filtration, and wallied and dried, a white taftelefs powder is obtained, mixed with ligneous threads, foluble in acids and alkalies, (o) An acid which (hall be afterwards defcribed. (p) Owing perhaps to the prefence of a little iron in the fulphat. (,0 The place which the fuberic acid occupies in the affinities of the alkalies, earths, and metallic oxides, as far as this fubjecl has been invelligated by Bouillon La Grange, will appear by the following Tables 4 Potass. Soda. Barytes. Lime. Sulphuric acid, Sulphuric acid, Sulphuric acid. Oxalic acid. Nitric, Nitric, Oxalic, Sulphuric, Muriatic, Muriatic, « » * # * • Suberic. Suberic. Muriatic, Muriatic, Suberic. Suberic. Alumina. Oxide of Tin. Oxide of Silver. Magnesia as lime. Sulphuric acid, * « # Oxide of Molybdenum. # * * Muriatic, Suberic. Muriatic, # « * Oxalic, Suberic acid. Suberic. Sulphuric, Oxide of Lead. Suberic. Oxide of Antimony. Oxide of Mercury. Oxide of Copper. * « * % ^ % Sebacic acid, Muriatic, Muriatic, Siiheric, • * • Suberic. * * « Nitric, Sulphuric, Manganese the fame. Suberic. Suberic. OXIDK * Ann, Je 44. 516 Itscompofi- (inn. j\ 1 ineraiogy of Shetland and Arran^ p. 167. Difcovery of white lac. C H E M I Barytes, Potafs, Soda, Lime, Ammonia, Magncfia, Alumina *. Mr Bouillon La Grange, to whom we are incl-bted for all the fafts relative to this acid, fuppofes that it is compofed of oxygen, hydrogen, and carbon : but Mr Jaraefon, in conlequence of the refult of a feries of ex- periments which he made on charcoal, has been led to fufpeft that it confifts entirely t)f carbon and oxygen. He found, that by the atlion of nitric acid upon char- coal, a brown, bitter, dcllquelcent mafs was formed, foluble in water, alcohol, and alkalies, and which emit- ted, particularly when heated, a very fragrant odour. This matter was more or lefs foluble in water according to the time that it had been expofed to the action of the acid. When the nitric acid ufed was concentrated, and confiderable in quantity, part of the charcoal was converted into an acid, which pofiefTed the characters of the fubericf . Thefe fafts are curious, and may extend our know- ledge of the nature of vegetable acids, but they are in- fufScient to prove the abfence of hydrogen in fuberic acid, becaufe charcoal cannot eafily be procured perfeft- ly free from hydrogen, and becaufe feveral of the pro- perties of fuberic acid indicate the prefence of hydrogen in it, its becoming bro^vn, for inftance, when expofed to the light. Mr Jamefon has obferved, that the acid which exifts ready formed in peat poffeffes the proper- ties of fuberic acid. Sect. XXIV. Of Laccic Jcid. About the year 1786, Dr Anderfon of Madras men- tioned, in a letter to the governor and council of that place, that nells of infefts, refembling fmall cowry (hells, had been brought to him from the woods by the na- tives, who eat them with avidity. Thefe fuppofcd nefts he foon afterwards difcoveredto be the coverings of the females of an undefcribed fpccies of coccus, which he fhortly found means to propagate with great facility on feveral of the trees and flirubs growing in his neigh- bourhood (r). On examining this fubftance, which he called 'white lac, he obferved in it a very confiderable refemblance to bees wax ; he noticed alfo, that the animal which fecretes it provides itfelf by fome means or other with a fraall quantity of honey, refembling that produced by our bees ; and in one of his letters he complains, that l.accic Acid. 5IS S T R Y. Part II. the children whom he employed to gather it were tempted by its fweetnefs to eat fo much of it as mate- rially to reduce the produce of his crop. Small quan- tities of this matter were fent into Europe in 1789, both in its natural ftate and melted into cakes ; and in 1793 Dr Pearfon, at the requell of Sir Jofeph Banks, undertook a chemical examination of its qualities, and his experiments were publiflied in the Philofophical TranfaC\ions for 1794. A piece of white lac, from 3 to 15 grains in weight, it/^'.jj.fig, is probably produced by each infeft. Thefe pieces are of a grey colour, opaque, rough, and roundifh. When white lac was purified by being ftraincd through muf. lin, it was of a brown colour, brittle, hard, and had a bitteridi tafte. It melted in alcohol, and in water of the temperature of 145^. In many of its properties it refembles bees wax, though it differs in others ; and Dr Pearfon fuppofes that both fubftances are compofed of the fame ingredients, but in different proportions. Two thoufand grains of white lac were expofed in fuch a degree of heat as was juft fufficient to melt them. As they grew foft and fluid, there oozed out ^50 grains of a reddifh watery liquid, which (melled like newly baken bread (s). To this liquid Dr Pearfon has given the name of lacc'ic acid* . * Pnr/ont It pofTefles the following properties : Trunjl. =25. A little of It having been evaporated till it grew very turbid, aflForded on ftanding fmall needle-fhaped cryftal& in mucilaginous matter. Two hundred and fifty grains of it were poured into a very fmall retort and diftilled. As the liquor grew warm, mucilage-like clouds appeared ; but as the heat increa- fed they difappeared again. At the temperature of 200°, the liquor diftilled over very faft : A fmall quan- tity of extraftive matter remained behind. The diftil- led liquor while hot fmelled like newly baken bread, and was perfeftly tranfparent and yellowidi. A (hred of paper ftained with turnfole, which had been put into the receiver, was not reddened ; nor did another which had been immerfed in a folution of fulphat of iron, and alfo placed in the receiver, turn to a blue colour upon being moiftened with the folution of potafs (t). About acid. Oxide of Iron. Oxide of Bismuth. Oxide of Arsenic *♦• *•» »«# Sulphuric, Muriatic, Nitric acid, Suberic. Suberic. Suberic. Cobalt and Zinc the fame with arfenic. (r) The Chinefe colleft a kind of wax, which they call pe-la, from a coccus, depofited for the purpofe of breeding on feveral (hrubs, and manage it exactly as the Mexicans manage the cochineal infeft. It was the knowledge of this that induced Dr Anderfon to attempt to propagate his infedl. (s) The fame liquid appears on prelfing the crude lac between the fingers 5 and we are told, that when newly gathered it is replete with juice. (t) A proof that the acid was not the pruiEc. Partir. Laccic Acid. CHEMISTRY. About one hundred grains of lliis dillilled liquM be- ing evaporated till it grew turbid, after being fet by fur a night, afforded acicular cryllals, which under a lens appeared in a group not unlike the umbel ot parf- ley. The whole of them did not amount to tile quar- ter of a grain. They tailed only bitterirti. Another lOO grains being evaporated to drynefs in a very low temperature, a blaekifli matter was left be- hind, which did not entirely dilappear on heating the fpoon containing it very hot in the naked fire ; but on heating oxahc acid to a much leis degree, it evaporated and left not a trace bchirid. Carbonat of lime diiiblved in this diftilled liquid with effervelcence. The ioUition tailed bitterifli, did not turn paper ilained w itli turnfole red, and ou adding to it carbonat of potais a copious precipitation eniued. A little of this folutiou of lime and of allcali being eva- porated to drynels, and the reiiduum made red hot, no- thing remained but carbonat ot lime and carbonat of potais. This liquid did not render nitrat of lime turbid, but it produced turbidnels in nitrat and muriat of barytes. To five hundred grains of the reddifh-coloured liquor obtained by melting white lac, carbonat of foda was added till the efFervcfcence ceafed, and the mixture was neutralifed ; for which purpofe three grains of the car- bonat were neceffary. During this combination a quan- tity of mucilaginous matter, with a little carbonat of lime, was precipitated. The faturated folution being filtrated and evaporated to the due degree, afforded on ftanding dcliqnefcent cryflals, which on expolure to iire left only a reiiduum of carbonat of foda. Lime-water being added to this reddifh-coloured li- quor produced a light purple turbid appearance ; and on ftanding there were clouds juft perceptible. Sulphuret of lime occafioned a white precipitation, but no fulphurated iiydrogen gas was perceptible by the fmell. Tinfture of galls produced a green precipitation. Sulphat of iron produced a purplifh colour, but no precipitation ; nor was any precipitate formed by the addition firlt of a little vinegar, and then of a little pot- afs, to the mixture. Acetite of lead occafioned a rcddifh precipitation, which rediffolved on addiiig a little nitric acid. Nitrat of mercury produced a whitifh turbid liquor. Oxalic acid produced immediately the precipitation of white acicular cryftals, owing probably to the pre- fence of a little lime in the liquid. Tartrite of potafs produced a precipitation not un- like what takes place on adding tartarous acid to tar- trite of potafs (u) ; but it did not diflblve again on adding potafs. Such were the properties of this acid difcovered by Dr Pearfon. Its dellrudlibility by lire, and its afford- ing carbon, diflinguifh it from all the acids defcribed in this article before the acetous ; and its peculiar fmell when heated, its precipitating tartrite of potafs with- out forming tartar, its bitterifh tafte, and its being con- 333 verted into vapour at the temperature of joo^, JIflin- Pyriniu- guilh it from all the acids hitherto examined*. ct-us Acid. Sect. XXV. Of Pyromucoui Add. 'Phil. PvROMUCous (v) acid is procured by diililling fugarp-sSs. or any of the fweet juices. As they foam very much, -5*° the retort ihould be large, and feveii-eighths of it empty . ^J^^J]"^ A prodigious quantity of carbonic acid and carbonated "lyni'mu- hydrogen gas is difcngaged: A very thin light coal rc-cous acid, mains behind in the retort. Morvcau found the glafs of the retort attacked. The quantity of fugar diftilled was 2304 grains; the coal weighed 9S2 grains. There were 4.28 grains of a brown liquor in the receiver, con- filling moltly of an acid phlegm. This redillilled gave 313 grains ot a liquor almoll limpid, the fpecilic gra- vity of which was 1,0115 at the temperature of 77". It reddened blue paper. This acid may be concentra- ted by freezing, or by combining it with fome bafe, potafs, for inllance, and decompoling the compound by a ftrouger acid, as, for example-, the fulphuric. It has a very lliarp talle. When expofed to heat in !(,„"„„. open vtffels, it evaporates, leaving a brown fpot. Dil- tics, tilled in dole vefTcls, it leaves charcoal behind it. It does not diffolve gold as Schriekcl and Lemery and feveral other ch>:mills affirmed. It does nut attack fiiver nor mercury, nor even their oxides f . Ii corrodes lead, and forms flyptic and long). Schriciet. cryflals. Copper forms with it a green folution : With iron it forms green cryflals ; with antimony and zinc greenifli folutions. The compounds which it forms are called /yromair/Vi'j. Combina- Its afiinities, according to Morveau, are as follows : tion«, and Potais, Soda, Barytes, Lime, Magnefia, Ammonia, Alumina, Jargonia J:. Metallic oxides as lafulfh. acid. Water, Alcohol. afiii.itics. yltnu de Chlm, xzii, 108. 5»1 ■3 Method of S E CT. XXVI. Of Pyro-lignous Acul It is well known that the fmoke of burning wood exceedingly oHer.livc to the eyes : And chemiils haveobuinmg long ago obfcrved, that an acid might be obtained by PVo-'iR- diftilling wood. nous aiiJ. It is to Mr Goettling, however, and to the Dijon academicians, who repeated his experiment, that we are indebted tor what knowledge we pofTel's of the peculiar properties of this acid, which, becaufe it is obtained from wood by means of fire, has been called ihe pyro' itgnous iicid (w). It appears to be the fame from what ever kind of wood it is obtained. Mr Goettling filled an iron retort with pieces of birch tree bark, and obtained by dillillation a thick, brown, very empyreumatic acid liquor. This liquor he allowed (u) On this addition, tartar, or acidulated tartrite of potafs, is formed, which precipitates, becaufe it is very little foluble in water. The addition of potafs diflblves it again, (v) Morveau called this ac\A fyrupous acid, (w) Goettling calkdit ligneous acid. i;79- 334 . C H E M I I'yro li;,^- allowej to remain at reft for three months, and then fe- ,"""' ^"^- paratcd from it a quantity of oil which had rifen to the top. Bv diililliiig this lifjuor again, and then fatura- ting it wlrli potals, and tvaporating to di jiicfs, he ob- tained a blown fahne mals ; whieh, by being reditlol- veJ in water, and evaporated, yielded grtyifli white cry- llals : Thefe cryftals were conipol'cd ot pyro-lignous acid and potafs. He poured upon them, by little and little, a quantity of fulphuric acid ; and by applying a gentle heat, the pyro-lignous acid came over in confider- able purity *. The Dijon academicians obtained this acid from beech wood ; by diftilling ; ^ ounces, they procured 17 ounces of acid ; which, when rettified by a fecond 514 dillillation, was of the fpecific gravity 1,02083. It5 proper- jt reddens vegetable colours : when expofed to a "".'"""'". flronff heat, it takes fire and is dellroyed. It unites Iiitio!is,aiid ° „ • 1 1 1 I aflinlties. ■^''^O' ^^^" ^^"" alcohol. Its compounds are called pyro-/igriifes. Its affiQitics, as fixed by Mr Eloy Bourfier de Cler- vaux and Mr de ^lorveau, are as follows : Lime, Barytes, Potafs, Soda, Magnefia, Ammonia, Oxide of z.inc, .— — manganefe, ■ iron, — — — lead, t — tin, cobalt, copper, ^— — — nickel, arfenic, ■ — bifmuth, mercury, — — antimony, filver, gold, platinum, Alumina, Jargonia f ? Sect. XXVII. Of Pyro-tartarous Acid. An acid may alfo be obtained by diftiUing tartar ; it is called pyro-tartarous add. p ^^-^ • It has an empyreumatic tafte and odour ; reddens the of pyro-tar- tinfture of turnfole ; but has no effedt on that of violets. tarousacid. Little is known concerning this acid, except that many of its properties are the fame with thofe of the pyro-lignous ; and Morveau conjettures that, if pro- perly purified, it would probably be difcovered to be the fame with it. The compounds which it forms are called pyro-tar- t rites. Its affinities are unknown. Morveau fuppofes that they are the fame with thofe of the pyro-lignous acid. liris Ann. de Cbim. xxii. aoS. S T R Y. Part II. they are obtained from vegetable fubftances. We have Vrgctable placed the laftic and facchokftic acids in the fame clafs; ^Acni?. becaufe thty bear a (Irong refcmblance to vegetable * acids, and becaufe they are evidently compofed of the fame ingredients with them. Vegetable acids are riiftinguiflied from all the acids p|,f|.|.|jj. defcrlbed in the beginning of this chapter, by their de- by fire. flniiSihility by fire. ,-,3 There is no circumftance in cheroiftry which has at- Cw ert. trailed greater attention than the poflibihty of convert-'''''^' """ ing the various vegetable acids into each other by means'" "">«'•■ of different procefiVs. To explain what pafies during thefe proceffes, it would be neceffary to know exaftly the component parts of every vegetable acid, the man- ner in which thefe acids are combined, and the affinities which exill between each of their ingredients. This, however, is very far from being the cafe at prefent. Though a vaft number of experiments have been made on purpofe to throw light on this very point, the diffi- culties which were to be encountered have been fo great, that no accurate refults have yet been obtained. It follows from thefe experiments, that all the vege- Inquiry in- table acids are compofed, chiefly at lead, of oxygen, hy-*° ^^'^ I'ro- drogen, and carbon ; but that the proportions differ i" Fhlir"inp°, every individual acid. We fay chiefly, becaufe it hasjients. been fufpefted from foroe plienomena, that one or two of thefe acids contain befides a little azot. Let us take a view of what is at prefent known of the compofition of thefe acids in their order. 1. As to carbonic acid, its compofition has been af- certained with tolerable accuracy ; it confifts of about 28 parts of carbon and 72 of oxygen. 2. By diftiUing 7680 grains of acetite of potafs, Dr Higgens obtained the following produfts * : ' Hi^gemca 5»9 3862,994 grains, j--,,, '473.564 1047,6018 78,0000 J 80,0000 340,0000 726,9402 J 26 Vegetable acids. The 18 preceding acids are all (except the laftic and faccholattic) denominated vegetable acids, becaufe Potafs, Carbonic acid gas. Carbonated hydrogen gas, Refiduum, confifting of carbon. Oil Water, .... Deficiency (x), ... This deficiency Dr Higgens found to be owing to a quantity of water and oil which is carried off by the elaftic fluids, and afterwards dcpofited by them. He calculated it, in the prefent cafe, at 700 grains of wa- ter and 26,9402 grains of oil. Now, fince acetite of potafs is compofed of acetous acid and potafs, and fince the whole of the potafs remained unaltered, it follows that the acetous acid was converted into carbonic acid gas, carbonated hydrogen gas, carbon, oil, and water ; all of which are compofed of oxygen, hydrogen, and carbon. Now 1473,564 gr. of carbonic acid gas are compofed of 1060,966 gr. of oxygen, and 41 ;,598 gr. of carbon. 1047,6018 grains of carbonated hydrogen gas, from a comparifon of the experiments of Dr Higgens and Lavoifier, may be fuppofed to confift of about 7 14,6008 grains of carbon, and 333,0010 of hydrogen. 200,9402 grains of oil contain 163,4828 grains of carbon and 43,4574 grains of hydrogen. 1040 grains of water contain 884 grains of oxygen and 156 grains of hydrogen. Therefor? (x) For 29,1 grains of oxygen gas had alfo difappeared from the air of the velTels. Partir. C H £ M Vegetable Therefore 3817,006 grains of acetouB acid are corn- Acids, pofgd of ,5,44,966 — 29,1 = 1915,866 grains of *"'""*'"~^ oxygen, 532,4584 grains of hydrogen, and 1 ;68,6Si6 grains of carbon. Confequently lOO parts of acetous acid are corapofed of 50,19 oxygen, 13,94 hydrogen, 35,^7 carbon. 100,00 Thefe numbers can only be confidered as approxima- tions to the truth ; for the objedl of Dr Higgens was not to afcertain the proportions of the ingredients which compofe acetous acid ; and therefore his experiments were not condufted with that rigid accuracy which would have been necefTary for that purpofe. It is extremely probable, that during the acetous fermentation, or the converfion of alcohol into acetous *t!erm/faJi,acid, a quantity of water is formed* ; and it is certain Crtil's Alt- that oxygen is abforbed. It follows from this that mh, j7S6. acetous acid contains more carbon and lefs hydrogen than alcohol. Now we have reafon, from Lavoiiier's experiments, to believe that alcohol is formed of 51,72 oxygen, 18,40 hydrogen, 29,88 carbon. Lavoifier fuppofes that this acid contains alfo azot. 3. Acetic acid is fuppofed to confift of the fame bafe with acetous acid, combined with a larger propor- tion of oxygen ; we would rather fay, that it is ace- tous acid combined with oxygen. 4. When oxalic acid is' diftilled with fix times its weight of fulphuric acid, the prodiiiEts are acetous acid, fulphurous acid, carbonic acid gas, and fulphuric acid . f'^^ji remains in the retort f . Hence it follows, that oxalic Jour, ,,'f acid contains more carbon than acetous acid ; but that i'i>/ 1785. it is compofcd of the fame ingredients. It has been fuppofed that oxalic acid is compofed of fugar and oxy- gen. Now fugar, according to Lavoifier, is compofcd of Hydrogen, - - - - 8 Oxygen, - - - - 64 Carbon, - - - - 28 Thefe proportions are rather unfavourable to that notion ; at lead if any dependence can be put in the compofition of acetous acid as deduced from the expe- riments of Dr Higgens. 5. Hermlladt dilfolved four ounces of tartarous acid in 16 ounces of water, and kept the folution in a veffel covered with p?per in a warm place. In three months the tafte of the folution was changed, and the air in the upper part of the vcfTel was found to be carbonic acid. In fix montlis the folution was converted into acetous acid. It follows from this experiment, that tartarous acid contains more carbon than acetous acid, and that their ingredients are the fame. If any doubts Ihould remain, the following experiment is fuiScient to remove them. Weftrum mixed ftrong fulphuric acid with tar- tarous acid, and added manganefe ; acetous acid was produced, and a great quantity of carbonic acid gas was difengaged. When nitric acid is dillilled off tar- tarous acid, it is converted into oxalic acid, as Scheele firft proved. Hence it has been fuppofed by fome, that oxalic acid differs from tartarous merely in contain. ing more oxygen : but this is very far indeed from be- I S T 11 Y. ZiS ing proved. According to HafTcnfratz, tartarous acid Prufljc contains a confiderable quantity of azot. , ' ' . . 6. When citrat of lime is allowed to remain in a bottle nightly corked along with a little alcohol, the citric acid is gradually converted into acetous acid *.• i/oW. Wellrum converted it into oxalic acid by means of ni- tric acid. 7. Malic acid was converted into oxalic by means of nitric acid by Scheele. It has been fuppofed to con- tain more oxygen than oxalic acid. Some of it is al- ways formed during the common procefs of converting fugar into oxalic acid. Were we to judge from an ex- periment, which, however, was not performed with- fufficient accuracy, we would conclude that the bafe of malic acid is gum ; for by diililling two parts of weak- nitric acid off one part of gum in a very fmall heat, we obtained a quantity of acid more in weight than the> gum, which exhibited feveral of the diflinguifhing pro- perties of mah'c acid. It was exceedingly light, white, and fpongy, and attrafted water very quickly from the atmofphere, and could not afterwards be brought by evaporation to its former ftate. 8. Scheele converted ladtic acid into acetous by mere expofure to the atmofphere, and found that a quan- tity of carbonic acid was difengaged. Hence this acid is merely the acetous with a fmaller proportion of car- bon. 9. The gallic acid, we have feen, contains more car- bon than any of the others. 10. Nothing is known concerning the compofition of the benzoic and fuccinic acids. Hermlladt fays he converted benzoic acid to oxalic by tneans of nitric acid : but Morvcau did not obferve that any change was pro- duced. J I. The bafe of camphoric Isprobably camphor. Though thefe eighteen are the only acids which have hitherto been examined with attention, it cannot be doubted that the number of vegetable acids, either ex- illing naturally, or at leall capable of being formed by art, is confiderably greater. Morveau has lately afcer- tained, that the red colours of flowers are owing to acids : This had already been conjeftured by Linnaeus, Sect. XXVIII. Of Pmjtc Acid. 530 About the beginning of the prefent century, Dicf-Difeovcry ■ bach, a chemiil oi Berlin, wifhing to precipitate a folu-"f Pf""'^"'' tloii of cochineal mixed with a little alum and fulphat ' of iron, borrowed from Dippel fome potafs, from which that chemill had dijl'illed feveral times his onmul oil. On pouring in the potafs, Dicfbach was furprifed to fee, iniltad of the red precipitate which he had cxpcfled, a beautiful blue powder falling to the bottom of the veffel. By reflcfting on tiie materials which he had employed, he eafily diicovered the method of procuring the blue powder at ))leafure \. This powder was callecl Pnijfmn , r, ii- blue, from the place where it was difcovered. It was ,00 Expe-- announced in the Berlin Memoirs for 17 10; but i^itrmmii. procefs was concealed, becaufe it had become a lucra- tive article of commerce. A method of preparing 't,., •'o'j p however, was publillied by Woodward in the Philofo-prcparinj;-- phlcal Tranfdftions for 1724, which he faid he had got it. from one of his friends in Germany. This method was as follows : Detonate togetiier 4 ounces of nitre and as much tartar, in order to procure an extemporaneous al- kali ; then add 4 ounces ot dried bullock's blood, m'x the- 33^ C H E M 531 Its ciiinpo lition difco' vered by Macquer. Pruflle the ingredients well togethei", and put them into a cru- " ' , cible covered with a lid, in which there is a fmall hole ; calcine with a moderate fire till the blood emits no more fmc ke or flame cap:ihle of blackening any white body expofed to it : increafe the fire towards the end, fo that the whole mattf contained in the crucible Ihall be mo- derately but fenlibly red. In this Hate throw it into two pints of water, and boil it for half an hour. De- cant off this water, and continue to pour on more till it come off infipid. Add all thefe liquids together, and boil them down to two pints. Diffolve two ounces of fulphat of iron and tight ounces of alum in two pints of boiling water ; mix this with the former liquor while both are hot'. An efFervefcence 'akes place, and a pow- der is precipitated of a green colour mixed with blue. Separate this precipitate by filtration, and pour muria- tic acid upon it till it becomes of a beautiful blue ; then wafli it with water and dry it. Different explanations were given of the nature of this precipitate by different chemiils. All of them ac- knowledged that it contained iron, but to account for the colour was the difficult point. Brown, and Geof- frey, and Neumann, difcovered in fuccefTion, tliat a great many other animal fubllances befides blood communica- ted to alkalies the property of forming Pruflian blue. Macquer undertook an examination of this fubftance, and puhlifhed the rcfult of his experiments in the Me- moirs of the French Academy for 1752. He oblcrved that, when alkali is added to a fohi- tion of iron in any acid, the iron Is precipitated of a yellow colour, r.od foluble in acids ; but if iron be pre- cipitated from an acid by an ailoli prepared as above defcribed, by calcination with blood (wliicli has been called a Pri^iav alkali), it is of a green colour. Acids dilFolve only a part of this precipitate, and leave behind an infoluble powder whicli is of an intenfe blue colour. The green precipitate therefore is compofed of two dif- ferent fubftances, one of wliich is Pruflian blue ; the other, as he afcertained by experiment, is the brown or yellow oxide of iron : and the green colour is owing to the mixture of the blue and yellow fubftances. When heat is applied to the iafolubie precipitate, its blue co- lour is dcllroyed, and it becomes exatlly fimilar to com- mon oxide of iron. It is compofed therefore of iron and fome other fubftance, which heat has the property of driving off. If this infohible precipitate be boiled with a very pure alkali, it lofcs its blue colour alfo, and at the fame time the alkali acquires the property of precipita- ting of a blue colour tolutions of iron in acids, or it has become precifely the fame with the PrulTian alkali. Pruffian blue, therefore, is compofed of iron and fome- thing which a pure alkali can feparate from it, fomething which has a greater affinity for alkali than for iron. By boihtig a quantity of alkali with Pruffian blue, it may be completely faturated with this fomething, which we fhall call colouring matter, and then it has loft all its alkaline properties. No acid can feparate this co- louring matter from iron after it is once united with it. When iron diffolved in an acid is mixed with an alkali faturated with the colouring matter, a double decompo- fition takes place, the acid unites with the alkali, and the colouring matter with the iron, and forms Pruflian blue. The reafon that, in the common method of pre- paring Pruffian blue, a quantity of yellow oxide is pre- cipitated, is, that there is not a fui&cient quantity of co- Acid. 5.^3 I S T R Y. Partll. louring matter (for the alkali Is never faturated with it) Pruillc to faturate all the iron difplaced by the alkali; a part of it therefore is mixed with Pruflian blue. Muriatic acid dilTolves this oxide, carries it off, and leaves the blue in a flate of purity. Such were the conchifions wliich Macquer drew from his experiments; experiments which not only difcovered the compofition of Pruffian blue, but threw a ray of light on the nature of affinities, which has contributed much towards the advancement of that important branch of chemiftrv. The nature of the colouring matter, however, was ftiU unknown. Macquer himfelf fuppofed that it was pure phlogifton ; but the opinion was untenable. He hrid fhewn that it pofLiTcd the property of forming neutral falts, and therefore Bergman and Morveau (ufpefted that it was an acid. Scheele undertook the tafk of examining its nature, and publifiied the refult of his experiments in tlie Stock- holm Tranfaftions for 1782. He obferved that the Pruffian allva!!, after being ex- pofed for fome time to the air, loft the property of form- ing Pruffian blue ; the colouring matter mu:l therefore have left it. He put a fmall quantity of it into a large glafs globe, Dj^orispo. corked it up, and kept it fome time ; but no changefed by was produced either in the air or the Pruffian alkali. Scheele. Something muft therefore difplace the colouring matter when the alkali is expofed to the open air, wliich is not prefent in a glafs vefTcl. Was it carbonic acid gas ? To afcertaiu this, he put a quantity of Pruflian alkali into a glafs globe tilled with that gas, and in 24 hours the alkali was incapable of producing Pruffian blue. It is therefore carbonic acid gas which difplaces the colour- ing matter. He repeated this experiment with this dif- ference, that he hung in the globe a bit of paper which had been previoufly dipped into a-folution of luiphat of iron, and on which he had let fall two drops of an alka- line lixivium, in order to precipitate the iron. This paper was taken out in two hours, and became covered with a fine blue on adding a little muriatic acid. Car- bonic acid, then, has the property of leparating the co- louring matter from alkali without decompoling it. ,,^ He found alfo that other acids produced the fame ef-Thecolour- feft. The cokiuring matter then may be obtained per-'"g matter haps in a feparate ftate. He accordingly made a num- P"^' ber of attempts to procure it, and at laif dilcovered the following procefs : He boiled together for fome minutes two ounces of Pruffian blue in powder, one ounce of the red oxide of mercury, and fix ounces of water ; then pafTcd the whole through a filter, and waftied the reli- duum with two ounces of boiling water. The oxide of mercury has a greater affinity for the colouring matter than the oxide of iron ; it therefore unites with it, and forms with it a fait foluble in water. The iron remains behind upon the filter, and the liquid is a folution of the colouring matter combined with mercury. He poured this folution upon half an ounce of pure iron-filings, and added at the fame time three grains of fulphuric acid. The iron feparates the oxygen from the mercury, in order to combine with the fulphuric acid; the mercury is precipitated in its metallic flate, and leaves behind it a quantity of fulphat of iron and of colouring matter diffolved in water, but not combined, as the colouring ., ir. matter is unable to feparate the iron from the acid '. ^„„ ^ He then diftilled in a gentle heat ; the colouring mat- ci>mie, i. terao- Part If. C H E M PrufTic ter came overly the time that one-fouvth of the liquor Acid. liatJ pnfled into tlie receiver. It was mixed, however, "~^ with a Imall quantity ot'fulphuric acid; from wliich he fepavated it by diiliUiiig a i'ccoud time over a quantity of carbonat of lime. The fulphuric acid comlMiits with the lime and remains behind, which the colourinjr mat- ter cannot do, bccaufe carbonic acid has a ilionger affi- nity for lime than it has. Thus he obtained the colour- ing matter in a ftate of purity. It remained now to difcover its component parts. He formed a very pui e PrufTian blue, which he dillilled, and increafed the fire till the velTel became red. The Imall quantity of water which he had put into the receiver contained a portion of the blue colouring matter and of ammonia ; and the air of the receiver confilled of azot, carbonic acid gas, and the colouring matter. He con- cluded from this experiment, that the colouring matter was compofed of ammonia and carbon. He mixed to- gether equal quantities of pounded charcoal and potafs, put the mixture into a crucible, and kept it red iiot for a quarter of an hour : he then added a quantity of fal ammoniac in fmall pieces, which he puflied to the bot- tom of the melted mixture, kept it in the fire for two minutes till it had ceafed to give out vapours of ammo- nia, and then threw it into a quantity of water. The folution polTefled all the properties of the Prufllan al- kali. Thus Mr Scheele fucceeded in forming the co- louring matter ; and it was confidered as proved that it was compofed of ammonia and carbon. But after the publication of Scheele's experiments, it was difcovered that ammonia itfelf is compofed of azot and hydrogen. It became therefore a queilion. Whether ammonia entered into the compofition of this fubftance, or merely its ingredients? VVIiether it was compofed of ammonia and carbon, or of azot, hydro- gen, and carbon combined in a different manner? This point has been decided by the following experiments: Mr Clouet made a quantity of ammoniacal gas pafs through a red hot porcelain tube filled with charcoal, and by this procefs formed a quantity of the colouring matter *. Here the temperature was fu high that the ammonia mull have been decompofed: and the colouring matter cannot be formed by combining ammonia and charcoal except at a temperature equally high. There is reafon therefore to fuppofe that the ammonia is de- compofed. When oxy-muriatic acid is mixed with the colouring matter, it communicates to it a quantity of oxygen, and caufes it in confequence to alfume very dif- ferent properties. When a fixed alkali or lime is added to it in this ftate, it is immediately decompofed, and converted into ammonia and carbonic acid gas. The colouring matter in this ftate contains all the ingredients neceflary to form thete two iubflances, namely, azot, hydrogen, carbon, oxygen : but in order to induce the ingredients to form thefe two compounds, the affiftance of an alkali or lime to combine with the carbonic acid is neceflary ; juft as fulphur combines more eafily with oxygen when united with an alkali or with iron than when feparate f . SuppL. Vol. I. Part I. f T>er:lolht, iiiJ. i. I S T R Y. The colouring matter, then, which we (hall hence- forth call the Prujfic acid, is compofed of azot, hydro- gen, and carbon; but the proportions of thefe ingrcdient.i have not yet been determined. It is confidered as an acid, though the prefence of oxygen has not been proved, bccaufe it has the property of turniing neutral falls with the fame bales as other acids. The Pruflic acid is exceedingly volatile, and evident- p,;,j^,i.j ly capable of exilting in a gafeous ftate. It has a pecu- f Hruffic liar odour, not dilagreeable, and which has been com-^''^- pared to the flowers of the peach. It has a fweetifti and fomewhat hot taft^, and excites cough*. * ScheiU. It has no affinity for alumina nor for alcohol f. i ^^^ This fubftance differs exceedingly in its adtion from all other acids. It is capable of combining, like them, with earths, (, 5 "^'^;o„ alkalies, and metallic oxides, and of forming compoundsou otK-r which have been denominated PniJJiats. But it enters'-'O'^'';'- much more readily into triple compounds with alkalies or earths, and metallic oxides, than into combinations with earths or alkalies feparately ; and though its affi- nity appears to be greater for alkalies and earths than for metallic oxides, yet when in a free or gafeous ftate it does not enter into combinations with earths or alkalies without difficulty, and it is ieparated from them much more eafily than from metallic oxides. Mere expofure to the light of the fun, or to a heat of 110°, is fuilicient for that purpofe. Its affinities are fuppoied to be as follows :, 53S Potafs, Soda, Ammonia, Lime, Barytes, Magnefia, Oxide of zinc, ■ — iron, ■' manganefe, cobalt, nickel, lead, ■ — tin, copper, ' bifmuth, — — — antimony, — — - — arfenic, ■ — fdver, mercury, gold, — platinum (y). Sect. XXIX. Of Formk ^cU. . In the 15th century feveral botatiifts obfcrved, with r,-/^' aftonifhment, that the flower oi luccory, when thrown „f'f™)''.'7 into an ant hill, became as red as blood : But it wasacij. Mr S. Fiflier who firft difcovered that ants poffefl'ed a peculiar acid, which he obtained b) diftiiling thefe ani- mals. His experiments were publiflied in the Philoiophi- cal Tranfaftions for 1670. Though Hoffman afterwards U u repeated Its affini- ties. (y) We fufpeft that this is not the real order of the affinities of this acid; the metallic oxides ought probably to be placed before the alkalies and earths, and the metallic Pruffiats ought to occupy the pface which is at pre- fent filled by the metaUic oxides. The reafons for this conjefture will appear afterwards. See Part III. chap. ii. {(.&., 23. of this article. 338 CHEMISTRY. Part IF. Formic repeated his procefs, little was known concerning tlni ^" ^' nature of this acid till Margraf uiidertohk its examiiia- * tion, and ptiblilhcd his experiments in the Berlin Me- moirs for 1749. The fpecies of ants from which the formic acid is obtained is the formica rufa, which reiide mod common. Iv in woods, or at leall in elevated and dry places. They have been found to contain the greatcft quantity of acid in the months of June and July. If at that feafon one of thcfe animals be prcffed upon paper tin- ged with turnfole, it changes the colour of it to a moil lively red: they even fometimes llain it merely by crawl- ^-o ing over it. Methods of There are two methods of obtaining the formic acid, obtaining JJftHlation and lixiviation. "• When the firft method is to be employed, the ants aie to be wadied clean, dried with ?. gentle heat, put in- to a retort, and diftilled with a moderate heat, gradual- ly increafed till all the acid has come over. It is mix- ed with an empyreumatic oil, from which it is feparatetl by paffing it tln-ough a flraiacr previoufly moiftened with water. By this procefs MelTrs ArdvilTon and Oehrn obtained from a pound of ants yi ounces of acid, the fpeciiic gravity of which, at the temperature of 6o^ • Z)//rf<. o» was 1,0075*. Morveau obtained from 49 ounces of tbeAcidof ants 23 ounces of pretty llrong acidf. Margraf added ^"".1777. a quantity of water; but it is evident that thia ferves '"rv'^^J, ««''ely to weaken the acid. ^Magnz'iZ When the other method is preferred, the ants are to /»r Art!, be wafhed in cold water, put upon a clean linen cloth, f Encyc. ^ an(j boiling water poured on them repeatedly till it can Mithod.i. extradl no more acid. The linen is then to be fqueezed, and the feveral liquors mixed and filtrated. This me- thod was firft ufed by Ardviflon and Oehrn : they ob- tained from a pound of ants an acid liquor which had more fpecific gravity than common vinegar. It is to be purified from the oil which adheres to it by repeated ' diftillations. After four diftillations the empyreumatic oil ftiU manifefts its prefence by its fmell, but this fmeli vanilhes if the acid be expoied for fome time to the air; a quantity of effential oil, however, ftill remains, which cannot be feparated. The fpecific gravity of the acid X Ardvljfon (hus rcttified is 1,0011 %. 'h-J ^'^"'' Hermftadt employed a third method. He exprefTed " ' the juice of dry ant's, and by this means obtained from albs, of thefe animals 21 oz. 2 dr. of juice, which on diftillation yielded a clear pure acid, equal in ftrength to very concentrated vinegar^. This acid feems to be capable of affuming a gafeous form ; at lead Hermftadt obferved, that when he put fome of it into a bottle with a glafs ftopper, the ftop- per was frequently raifed by an elaftic fluid making itsefcape, and that after fome days it had loft its fmell ||. When this acid is boiled with nitric acid, a gas is extri- cated, which renders lime-water turbid, and has a very 5^.rf^i^.»,pu''gentodour^. * , r r 11 r Hid. This acid has a ftrong but not unpleaiant ImeU, a caui- tic tafte, and when much diluted a pleafant acidity. When • Hid. "'o'^ concentrated, its fpecific gravity is 1,0453 *• One part of this acid, mixed with 75 parts of water, gives a faint red to fyrup of violets ; mixed with 430 parts of water, it reddens paper coloured with turnfole; reixed with 1300 parts of water, it produces no efFeft ^MorvcM, on the infufion of turnfole f. It mixes readily with al- f.Ct. cohol. $ CreU's 17S4. J4I Its proper- ties. 11 Jiid. Sel.acic .Adi. It unites readily with the other acids. When boiled with fulphuric acid, it becomes black. White acrid va- pours rife when the mixture becomes hot; and when it "' boils, a gas rifes which unites with difficulty to water and lime-water; the formic acid is again obtained, but its quantity is diminiftied *. * Jtid, Nitric acid decompofcs it altogether, and is itfelf converted into lutrous acid. Muriatic acid docs not al- ter it. Oxy-muriatic afts like nitric acidf. f liu. Its compounds are called ybrm/af/. J-iz Its affinities are the fame with thofe given above for ''* '^°™' r. rt- • , ° ( nurds ani ^Ihnities. the Prufiic acid. Sect. XXX 54.'! Of Seback JclJ. Chemists had long fufpefted that an acid could be uifcovery obtained from tallow, on account of the acrid uature of oi Icbacic the fumes which it emitted at a high temperature ; but *'^"^' it was M. Grutzmacher who firft demonftrated this acid in a diflei tation De OJftum Medulla, publiftied in l 74B J. } LmitiardU Mr Rhodes mentioned it in i 753, and .Segner publilbed a differtation on it in 1734, and Crell examined its pro- perties very fully in two diftertations publiflied in the Piu'l. Tranf. for T780 and 1782. It was called at firft acid of fa!, and zht-vw ards febacic acid. It may be procured by heating together a mixture of fuet and lime. Sebat of lime is formed, which may be purified by folution in water. It is then to be put into a retort, and fulphuric acid poured on it. Sebacic acid pafTcs over on the application of heat. Sebacic acid has an acid, fharp, bitterilh tafte, and a its pioper- very pungent fmell. It reddens tint^ure of litmus. ties, Heat caufes it to aiTume a yellow colour. It oxidates filver, mercury, copper, iron, lead, tin, zinc, antimony, manganefe. It does not att upon bifmuth, cobalt, nickel; When mixed with nitric acid it diffblves gold. Its compounds are c^\iA febats. Its affinities, according to Morveau, are as follows Barytcs, Potafs, Soda, Lime^ Magnefia, Ammonia, Alumina, Jargonia §, Oxide of zinc, — — — manganefe, — iron, . — lead, tin, I — cobalt, — copper, nickel, arfenic, — bifmuth, — mercury, — antimony, filver. 545 , Cempnunds and affini- ties. § Vattqite-^ iin, Ann. de Cbim. xxii. »0S. Sect. XXXI. Of Bomlyc JciJ. 546 Mr BoissiER DE Sauvages obferved, that the juice jjij-^^^^y of the filkworm, in the difeafe called in France wi//?a- of hombjc dine, was acid ; and Chauffier remarked, that the Clk- acid. worm, after being converted into a butterfly, gives out fart 11. Zoonic aliqiior which turns vegetable blues to a red. He found, ^cul fij^j during the time that tlie animal was forming its ' cocon, the acid was depolited in a rifervoir near the a- nns. By means of a pair of fcifF.irs he collefted fome which reddened blue paper, united with alkalies with effervefcence, and even attacked the icilfixrs. He after- wards coUeftfd it by iiifufiiig tlie chryfalids in alcohol, which diflblved the acid, but left the impurities un- touched. This acid has never been examined with attention ; fo that almolt all it.'i properties are unknown. C H E INI I S T R Y. 339 ^lethml of obtaining zounic a- cid. • Ann. f/' Cb'in. xxvi. 54S If. prcper Ues. \BirthaUct, Ann, dd Chim. Xjvi. 549 Animal icids. Sect. XXXII. Of Zoonk /tciJ. Mb. Berthollet has obtained a peculiar acid by di- ftilling vegetable and aniiiial fub'.lances, to which he has given the name of the zoonic aciil*. He procured it by dillilling the gluten of wheat, the yell of beer, bones, and woollen rags ; and concludes, therefore, that it may be produced by the dillill.ition of all auiiiLil fubltances. To obtain this acid pure, he mixed lime with the di- ftiUed liquid, after having feparaled the oil, which it always, contains (for the produA of the diltillatiou of animal fubftanccs is chiefly oil and carbonat of ammo- nia.) He boiled this mixture till the carbonat ot am- monia was exhaled : he then filtered it, added a little more lime, and boiled it again till the fmell of the am- monia had gone off entirely. The liquor, which now contained only zoonat of lime, he tillered again, and then added a little water impregnated with carbonic acid, in order to precipitate any lime which might hap- pen to be dilTolved in the liquid without being com- bined witli the zoonic acid. After concentrating the zoonat of lime, he mixed it with priofphoric acid, and diftilled it in a retort. At a beat ne.uly equal to that of boiling water, the zoonic acid paifes over in a date of purity. The zoonic acid has an odour like that of meat when frying, aird it is a6lually formed during that procefs. It has an auftere talle. It gives a red colour to paper tinged with turnfole. With alkalies and earths it produces falts, which dp not appear capable of cryftallizing. It forms a white precipitate in the folutions of ace- tite of lead and nitrat of mercury. Part of the zoonic acid feems to be deftroyed by the aftion of heat during the diftillation of the zoonat of lime with phofphoric acid ; for the liquor, which is in ebullition, becomes brown, and grows black at the end of the operation ; hence Mr Berthollet concludes that the zoonic acid contains carbon. The zoonat ot filver, when kept, becomes gradually brown j hence he con- cludes that the acid contains hydrogen. Thefe conclu- fions he draws from a very ingenious theory of his, which has been already dcfcribed in the article Bleach- ing in this Supplenienf\. The five preceding acids have obtained the name of animal acids, becaufe they are all obtained from the ani- mal kingdom. It can fcarcely be doubted that a more accurate examination of animal fubftances will add con- fiderably to the number of thefe acids. Sect. XXXIII. Of Arfcnic Acid. Arsenic acid, which was firft difcovered by Scheele, may be produced by fimply mixing the white oxide of arfenic with oxy-murlatic acid, and applying a heat filf- Arfcnic ticient to fublime the muriatic acid. The theory ol ^ . this operation is evident : the white oxide has a greater . \ affinity for oxygen than muriatic acid has ; of courfe M 1 A of it combines with it, and is thus converted into arfenic "'"■''''■"S acid, and the muriatic acid is eafily fublimcd by apply-"''''"*' ing heat. Landriani has infoimed us, that this acid may be al- fo formed by fubliming feveral times luccelfively the while oxide of arlenic, and taking care every tinx to re- new the air. This proccis is equally fimplc ; the oxide combines at a high temperature with the oxygen of the atmofphere. This acid is exceedingly fixed. When expofed to j^, proper, the air it attracts humidity, and at laft becomes li-tics. quid. At the temperature of 60" it difTolves in two- thirds of its weight of water. Its folution may be eva- porated to drynefs, and even converted into a glafs, which attrafts moifture from the air, and adls power- fully on the crucible. It is poifonous as well as the white oxide of arfe- When expofed to a red heat, it is partly decompofed and converted into white oxide of arfenic f. \U. It does not aft upon gold, platinum, filver, mer- cury. It oxidates copper, iron, lead, tin, zinc, bifmuth, antimony, cobalt, nickel, manganefe, and arfenic, and in a very ftrong heat, mercury and filver. According to Berthollet's experiments, arfenic acid is compofed of eight parts of white oxide of arfeiu'c and one part of oxygen. Its compounds are called arfeniats. Its affinities are as follows : Jjime, Barytes, Magnefia, Potafs, Soda, Ammonia, Oxide of zinc, — — — manganefe, — — iron, — lead, — — — tin, — — — cobalt, copper, nickel, bifmuth,, mercury, antimony, filver, gold, platinum, * ScheeU^ Us ct)ni- piiindsand aflunities. Alumina, Jargonia % ? Water. ^ Vauqiirlitti Ann. Ji Clim. xxii. »0S. , Propertici exannncd„f,;;ng(l,j Sect. XXXIV. Of Tungstic AciJ. TuNGSTic acid, or oxide of tungften, was firfl dif- covered by Scheele ; but the acid which he was not pure, being compofed, as Mr Luyart has (hewn, acid, of nitric acid, amn;onia, and tungilic acid. The real acid is infolublc m A-ater, taftelefs, and incapable of turning vegetable blues red till it has been firft rendered U u 2 folublc Moiybdlc Acid. • Rinaan. CHEMISTRY. 554 Its cora- pnunds and alTirities. } VaujwHn, jinn, de Cbim. mil. 3o8. Properties of molyb- Tb'Ufbphica i. >i2. foluble by being partly combined with ammonia. It is of a beautiful yellow colour, which becomes bhie when expofed to the light, or heated violently in clofe vefTels. It does not recover its yellow colour except by calcina- tion in the open air, and then increafes in weight. Wlicn put into muriatic acid along with tin, zinc, or iron, the liq-Jor becomes blue *. Treated with acetous acid, it becomes blue. When reduced to a glafs with phofphat of foda, the blTie colour appears and difap- pears according as the blue or yellow part of the flame is direfted to it, as happens to manganefe. Probably this blue fubftance is an oxide of tungften with a (mai- ler quantity of oxygen. Its compounds are called iungstats. Its affinities are as follows f : Lime, Barytes, Magnefia, Potafs, Soda, Ammonia, Alumina, Jargonia $ ? S E CT. XXXV. Of BJolybdlc Acid. Concrete moIyHdic acid, firll difcovered by Scheele, is white, and has an acid but metallic tafte. Its fpecific gravity is 3,75 J. It is not altered in the air. When heated in a crucible till it is beginning to melt, it ex- periences no alteration. It remains fixed even in a great fire as long as the crucible is covered ; but the moment it is uncovered the acid rifes unaltered in a white fmoke. It dilTolves in 570 parts of water. The folution red- dens turnfole ; nitric acid does not affeft it, but fulphu- ric and muriatic acids diffolve it by the afiiftance of heat. It may be prepared by treating the ore of molybde- num with nitric acid, and walhing the acid when form- ed in water. When combined with potafs, it forms a colourlefs fait. Mixed with filings of tin and muriatic acid, it imme- diately becomes blue, and precipitates flakes of the fame colour, which difnppear after fome time, if an excefs of muriatic aciv, that all the former analyfes were inaccurate. ayii. A hundred parts of this mineral, reduced to a fine powder, were mixed with 300 parts of the faturated carbonat of potafs, and about 4000 parts of water ; and this mixture was expofed for an hour to a boiling heat. He obferved, ift, that when thefe matters began to aft upon each other there was produced a ftrong effervef- cence, which continued a long time ; 2d, that the o- range colour of the lead became a brick red ; ^d, that at a certain period the whole matter feemed to dilTolve } 4th, that in proportion as the effervefccnce advanced the matter reappeared under the form of a granulated powder of a dirty yellow colour ; jth, that the liquor alTumcd a beautiful golden yellow colour. When the effervefcence had entirely fubfided, and appeared to have no longer any aftion on the fubftances, the liquor was filtered, and the metallic dull coUefted on the paper. After being walhed and dried, it weighed no more than 78 parts: the potafs, therefore, had taken fromit22part5. He poured upon the 78 parts juft mentioned fome of the nitric acid, diluted in 1 2 parts of water, which produced a briilt effervefcence. The greater part of the matter was diffolved : the liquor affumed no colour, and there remained only a fmall quantity of powder of an orange-yellow colour. The liquor of the refiduura was feparated by the help of a fyphon, the matter wafh- ed feveral times, and the wafhings united with the firft liquor. This reliduum, dried, weighed no more than 14 parts : from which it follows, that the nitric acid had dilToived 64. He again mixed thefe 14 parts with 42 parts of the carbonat of potafs and the neccffary quantity of water, and Part II. S57 And difco very of chromic Mid. C H E M and then treated them as before, and the phenomena were the fanne. The liquor, after being filtered, was united to the former ; and the refiduum, walhed and dried, weighed no more than two parti, which were ftiU red lead, and therefore thrown away. The two nitric folutions, united and evaporated, pro- duced 92 parts of nitrat of lead, cryftallized in oftahe- dra, perfe(?Hy white and transparent. Thefe 92 parts of nitrat of lead, dilTolved in water, were precipitated by a folution of the fulphat of foda. This produced 81 parts of the fuljihat of lead, which were equivalent to 56,68 of metallic lead. The alkaline liquors were found to contain a fait com- pofed of potafs combined with a peculiar acid, which Mr Vauquelin afterwards called chromic acid. Thefe liquors, fubjefted to evaporation until a faline pellicle was formed on their furface, produced, on cool- ing, yellow cryftals ; among which there was a carbonat of potafs, not decompofed. Thefe cryllals, dilTolved in water, and the folution united with the mother-water, the whole was mixed with weak nitric acid until the carbonat of potafs was faturated. The liquor then had a very dark orange-red colour. Being united with a folution of the muriat of tin, newly made, it Crft af- fumtd a brown colour, which afterwards became green- iih. Mixed with a folution of the nitrat of lead, it im- mediately produced the red lead. Lailly, evaporated fpontaneoufly, it produced ruby-red cryftals, mixed with cryftals of the nitrat of potafs. Ninety-eight parts of this mineral, decompofed as above-mentioned, having produced 81 parts of the fulphat of lead, 100 parts would have given 82,65, which are equivalent to 57, t of metallic lead. " But admitting, as experiment proves (fays Mr Vauquelin), that lOO parts of lead abforb, in combining with acids, 12 parts of oxygen, the 57,1 of metallic lead ought to contain in the red lead 6,86 of this principle, and we ought to have for the minerali- zing acid 36,4. Chromic acid cryftallizes in the form of elongated prifms of a ruby colour. When mixed with filings of tin and the muriatic acid, it becomes at firil yellowifh brown, and afterwards af- fumes a beautiful green colour. Wlien mixed with a little alcohol and nitric acid, it immediately affumes a bluilh green colour, wliich pre- ferves the fame fhade even after deficcation. Ether alone gives it the fame colour. With a folution of nitrat of mercury, it gives a pre- cipitate of a dark cinnabar colour. With a folution of nitrat of filver, it gives a precipi- tate, which, the moment it is formed, appears of a beau- tiful carmine colour, but becomes purple by expofure to the light. This combination, expcfed to the heat of the blow-pipe, melts before the charcoal is iiiflamedj It affumes a blackilh and metallic appearance. If it be then pulverifed, the powder is ftill purple ; but af- ter the blue flame of the lamp is brought in contaft with this matter, it aflumes a green colour, and the fil- ver appears in globules difleminated throughout its fub- ftance. With nitrat of copper, it gives a cbefaut red precipi- tate. With the folutions of fulphat of zinc, muriat of blf- muth, muriat of antimony, nitrat of nickel, and muriat of platinum, it pruduces yellowifti precipitates whea I S T R Y. 34r thefe folutions do not contain excefs of acid. With Chromic muriat of gold, it produces a greenilh precipitate. , "^^ • , When melted with borax or glais, it communicates * to them a beautiful emerald green colour. Paper impregnated with chromic acid affumes in the light a greenilh colour. Wiien mixed with muriatic acid, the mixture was capable of diffolving gold like aqua regia ; when this mixture of the two acids is diftilled, oxy-muriatic acid is diiengaged, and the liquor affumes a very beautiful green colour. Sulphuric acid, while cold, produces no effeiSl upon it ; but when warmed, it makes it affume a bluilh green co- lour, probablyby favouring the difengagement of oxygen. When this acid is heated along with charcoal, it is reduced to the metal called chromum. It is therefore compofed of this metal and oxygen. From Vauque- lin's experiments, it appears to contain one part of chromum and two parts of oxygen. Such are the properties of tljis acid, as far as they have hitherto been difcovered. Vauquelin is the only chemift who has examined it ; and from his memoir the above account has been taken *. * Ano.dt Cbim. xxir. The four laft defcribed acids are called metallic aciJi, phH^jopkkal- becaufe they are compofed of metals and oxygen. Mog^-^im, It is believed that moft of the metals, we would ra-'-^?';- ^"d ther fay of the metallic oxides, are capable of being 5^^- converted into acids by being combined with oxygen. Metallic It is certain that this is the cafe with platinum ; andaciJe. Hermftadt, by diftilling nitric acid off tin, converted it into a white mafs, foluble in three parts of water, which has been called y/ann/c acid\. Several -maxi. oi \ Ann. ie the metallic oxides aft the part of acids : But no com- Chim. iv. plete fet of experiments on this important fubjeA has '*^' yet appeared. Chap. VI. 0/" Affinitt. 5 60 The meaning of the word affinity has been already I'"P"r"nce explained; and it muft appear evident, from the ufe"'^ '''''"''''" which has been made of it in this article, that the con- fideration of the nature of affinity is the moft important part of chemiftry. While its laws are unknown, che- miftry is not a icience, but a wildernefs of fafts with- out beauty or regularity : every thing is equally per- plexing and inGornprchenfible. The chemift, inftead of being able to trace the operations of Nature, is loft in ' an endlefs maze of uncertainty, without a guide to con-- duft him, or a ray of light to illuminate his Iteps. It is the knowledge of affinity which difpels the dark- nefs, I'emoves the confufion, (liews us the order which fubfifts in all the phenonvcna of nature, points out their ' dependence on one another, and enables us to diredl them as we think proper, to make them fubfervient to the improvement of the arts, and thus to render them the minifters of our comforts and enjoyments. j^r I. When two bodies are united together by affinity,'' tJiiitcj how fniall a portion foevcr of the compound we exa- ■"!"'"' ''*''"" mine, we (hall always find it to contain both of the in-., I5 " gredie'nts. From this it is evident, that affinity com- bines bodies, particle witii particle. By particles we do not mean wliaC philofophers have called atoms, or the fmalleft parts into which it is^pof- fible to divide matter ; but the fmalkft parts which nKvke- 343 CHEMISTRY. Part 11, Aflini-y. make an integraril of any fubftance. Water, for in- parently in contaft ? or ftippofing that it does athe circumllances are the fame, querift to the ifudy of Bofcovich's curve; but as our 564 Now what are the laws which :iffinity follows ? There modern chemiils are not generally verfant in fuch flu- Wheiher Jj 3 fpecies of attraftion which matter pofl'cfles, called -ijies, we beg leave to obferve, in this place, that we have the fame „,avitation, the laws of which were inveltigated by Sir no proof whatever of abfolute contact between bodies, vitatioir' I'**^" Newton. Is affinity the fume with gravitation, On the contrary, it is highly probable, we had almoil or does it follow different laws ? faid demonffrable, that particles are in every indance at Upon a flight view of thefe two attradlions, their fome diflance from one another. For, on the fuppofi- phenomena appear very different. Gravitation afts at tion that two bodies were in aftual contact, their at- very great diflances ; affinity not until the bodies are traftlon for each other would not only be as great as mixed together : Gravitation adts on the whole mafs ; poffible, but as great as the attraftion of any other body affinity only on the particles : Bodies gravitate to one for either of them could poffibly be : Confequently, it another direttly as their maffes, and inverfely as the neceffarily follows, that, iince bodies chemically com- fquares of their diflances. But how can affinity follow bined fan be feparated, they are not in aftual contaft(A); thefe laws, when it does not ad till the bodies are ap- but if they are not in contad, their dillance from one another (a) Perhaps the following demonflration, which we borrow from the ingenious Mr Broughman, will render Plate ti,is „jor£ evident. In lig. 7. let the body A have foi" P an [attradion which at the diftan^ of AP is propor- XVII. tional Part FT. C H E M Affi'iity. anottior may vary in different c:ifes, and the force "'~v~~'of alfinity will vary with the diilance. Here then is a real'on wliy tlie affinity of different bodies va- ries in ftrength. Sulphuric acid, for inllance, has a tlronger affinity for barytes than for lime; becaule when tlie combinations are formed, the diftance between the acid and barytes is iiot fo great as that between the acid and iime. But why do the diftances differ? If afKnity be the fame with gravitation, it niuil tend to bring the particles nearer one another : And what then prevents the lime from approaching as near the acid as the barytes does ? We reply, the Ji;;ure of its parlulfs. This anfwer was firll given to the quellion by Bnifon, and it is fully ade- quate to folv.e the dilficulty. The particles of bodies, indeed, are a great deal too nunute for us to difcover their figure by adual infpedion ; but the phenomena of ^ryllallization fhew us that this diil'erence actually exiils. The crvftals of every body alTume^a peculiar figure. Now as thefe cryltals are all formed in the fame man- ner, and by the fame law, it is impofTible to conceive ' any other reafon for their variety but the difference in the form of the particles which compofe them. But why does one body difplace another ? When a particle of barytes is brought within a certain dillance ot a particle of fulphuric acid and lime combined toge- ther, affinity aits and draws them nearer to one ano- ther ; and the barytes, from its figure, approaches near- er the acid than the lime could, and forms with it a compound, the figure of which is fuch, relatively to that of the lime, that they cannot approach within a fmall enough dillance of each other to counteradl the attrac- tion of the earth. Accordingly no compound is form- ed ; for all that is meant by two particles having form- ed a con\pound, is, that their attraftion for each other is greater than the attraftion of the furrounding bodies for either. Having thus feen that none of the phenomena of n/"- qusntly It Jimty are inconliftent with their refulting from the fur- . ^rj "."^ces which brinsj about the phenomena of gravitation, as the/tfir«, we have a riglit to concfude, that it is at ieaft fiigtily probable, that all the motions of the corporeal woild are produced by the fame power which, though not efTen- tial to matter, was imprefled upon every atom of it by the Great Creator when he formed this univerie ; and that as the effects of this power are modified according to the fituation of the bodies on which it acts, they are known by the different names of gravity, adhefion, co- hefioH, and ajjinity. Gravity is the attraflion between bodies fo diflant, that the maffes alone influence the refult, and that the 586 Confe- IS TRY. 343 power may be confidered as placed in the centre of the Affinity, attrafllng bodies. '• " 'v ^ Adhesion fuppofes a diflance too fmall for our fenfes. It has been demonllrated to be proportional to the number of touching points, which depends upon the figure of the particles that form the bodies. ' CoHtsiON takes place only between particles of the fame nature. Thefe, inllcad of touching only in one fuperlicics, as In adhefion, touch In every point where their figure will allow contaCl ; confcqueiuly the force of cohefion alfo mull dently owing to the fmaller cohefion of alcohol. Mr Morveau's method muft therefore be confined to thofe eafes in which the cohefion of the hquid is ftronger than its adhefion to the folid, which may be known by the furface of the fohd not being moiftened ; and to thofe in which the cohefion is not much inferior to the adhefion ; for then, it is evident, that the force of cohefion will be increafed as tiie force of adhefion. Let us fuppofe, for inftance, that two folids, A and B, are made to adhere to the furface of a liquid, and that A can only form an adhefion with 50 particles of tike liquid, whilft B adheres to 100 ; it is evident that a much fmaller force will deftroy the cohefion of the 50 particles to which A adheres with the reft of the li- quid, than what will be required to deftroy the cohe- fion of the '100 particles united to B with the fame • Mirvwu, liquid*- r ^, ■.:, 1, u V J £„cyc. Mc- The method of Mr Morveau, then, may be applied tbod. Chim. ^Jth accuracy in both cafes ; and luhen they occur can Adhc. ^i^jy ^^ determined by experiment. It cannot, how- ever, be applied indifcriminattly even then ; for unlefs the folid and the fluid be prefented in fuch a ftate that S T R y. Part II. no gas is extricated when the adhefion takes place, an Affinity, accurate judgment cannot be formed of the force of ad- *"~~v~-~' hefion. Wlien marble (carbonat of lime), for inftance, is applied to the furface of fulphuric acid, there is an extrication of gas, which very foon deftroys the adhe- fion, and prevents an accurate refult. Were it poffible to employ quicklime inrtead of marble, this would be prevented ; or if this cannot be accompllflied, why might not lime be employed, united with fome acid that would not aifume a gafeous form, and at the fame time has a weaker affinity than fulphuric acid for lime ? Wliy miglit not the phofphat of lime, for inftance, be ufed, wliich may be reduced to a ftate of hardnefs fuffi- ciently great for the purpofe ? The extrication of gas, during the application of metals to the furfaces of acids, might be prevented by oxidating their furfaces. It is true, indeed, this could not be done with all the metals, on account of the nature of the oxide, but it might with feveral ; copper, for inftance, and filver. It cannot be doubted, that by thefe methods, and other contrivances that might be fallen upon, a fufficient number of re- fults might be obtained to render this method of the greatcft importance. It is rather furprifing, therefore, that it has never been profecuted. Mr Kirwan has propofed another method of folving AndKiO" the problem. While he was engaged in his experiments wan. on the ftrength of acids, he obferved that the quan- tity of real acid neccflary to faturate a given quantity of each of the bafes, was inverfely as the affinity between the refpefiive bafes and the acid ; and that the quan- tity of each of the bafes neceffary to faturate a given quantity of acid was diredlly as the affinity between the bafc and the acid. Thus 100 grains of each of the acids require more alkali for faturation than lime, and more lime than magnefia, as may be feen in the foUow- ins table : 1 574 100 grains fif Potafs. Soda. Lime. Anini. Mag. Alum. Sulphuric acid 215 165 110 90 80 75 Nitric acid 215 16? 96 87 75 65 Muriatic acid, 215 158 89 19 71 55 art /an. He concluded, therefore, that the affinity between acids and their bafes may be rtlimated by the quantity of bafes neceffary for faturation. Thus the affinity be- tween potafs and fulphuric acid is 215, and that be- tween nitric acid and lime 96 *. ♦?*■/■_ We have mentioned formerly, that the principle on Tnsn/.iyi^i which Mr Kirwan calculated the ftrength of the acids was founded on a miftake. It muit follow of courfe, therefore, that the numbers which reiult from it muft alfo be wrong. This Mr Kirwan has acknowledged, and feems to have given up all thoughts of afcertain- ing the ftrength of affinities by this method. But be- fore it be abandoned altogether we wi(h the following obfervations were confidered. ,_- Bergman long ago eftabhfhed as a principle, under Attempt « the name of a chemical paradox, that the Jlronger a«)/ remedy thi fah -was, the lefs of any other it required for /aturation.^V Pi Thus, according to him, 100 (d) Striftly fpeaking, this is owing not fo much to a decreafe of theTorce of adhefion, as of that of the co- hefion of the fluid itfelf. Part II. Ariii.ity. CHEMISTRY. 100 parts of potafs require 78,5 Sulphuric acid, 64 Nitric, 51,5 Muriatic, 41 Carbonic, 177 Sulphuric, 135,5 Nitric, 125 Muriatic, 80 Carbonic. loo parts of foda 347 ted by Morvcau *, evidently rtjfolvea itfelf into ttic two Affi nity. ^ following : * F 1. A iafi requires t/je more of an acid for faturation ^,^,,^^-^ ' thejlnnger its affuiity for that acid is. Ci/w.i. 597. 2. An acid requires the more of any bafe for fatura- tlon the greater ajfiiii/y it has for that bafe. In order to judge of tlie truth of the tirlt of thcfe pro- pofitions, let us examine the following table, dra« n up This propofition, which has been admirably illuftra- from the experiments of Bergman, Wenzcl, and Kirwan. 1 00 parts of Bergman Sul^^huric. N'.tric. Muri.itic. Wenzel. Sulphuric. Nitric. Muriatic. Suljihuric. KlRWAH. Nitric. Muriatic. Barytes '5.4 3c,8 Potafs 78,6 6+ 51.5 82,4 107,7 54 81,8 87.1 78,2 Soda •75 135.5 lis 125,8 166,6 83 129.4 136,1 114,2 Lime 143.7 •34.4 7C.45 •47.74 •195,6 103,6 141 180 86 Magnefia 173.67 159,25 82,92 181,8 257.15 122,27 •70.5 255 104,275 Ammonia 142,42 201,22 96,25 •87.5 233 116 Alumina 211,11 220,2 77,7 68,7 38,6 It 13 evident at firft fight, that Bergman's experi- ments correfpond exaftly with the propofition. To fa- turate, according to him, 100 parts ot potafs, requires 78i6 of fulphuric acid, 64 of nitric, and 51,5 of mu- riatic acid. There is only one deviation from the pro- pofition in the whole table, and this regards barytes, which, according to him, is faturated with i -,4 of fulphuric and 3", 8 of muriatic acid. But Mr Morveau has (hewn, by ftveral accurate experiments, that bary;. tes requires much more fulphuric acid for Saturation ^ P than Bergman fuppofed *. And Klaproth has fhewn, Meilnd. that 100 parts of barytes require 49,2 of Urongfulphuric CiiOT. i. 59i.acid for faturationj-. And Dr Withering's calculation \ \ Chim. agrees almoft exactly with this ; nor does that of Four- -"fr"' croy differ much from it f. Inifead of 15,4 of fulphuric X Phil. acid, therefore, which, according to Bergman, are ne- ?'ri7n,/:i784.ce(rai-y to faturate 100 of barytes, it (hould be 42,8. \ Ann.d! The firft and laft columns of Wenzel and Kiruan's ""■"■ •''experiments agree equally well with the propofition, but the fecond deviates from it completely. Wenzel pro- bably might have been mifled by the manner of per- forming his experimentsj but the fame objedlion docs not fccm to lie againft thofe of Kirwan. It can fcarccly be doubted, however, to whatever caufe the error is to be imputed, that the numbers in the fecond column of Mr Kirwan's table are too large. The following experiment of Morveau is fufficient to fhew this. According to Mr Kirwan's experiments, the propor- tions of acid and alkali in the four following falts are as under : Sulpha«f potafs 1^;;^^^^ r'08,7 Sulphat of lime NItrat of potafs Nitrat of lime 100 80,6 100 83.33 100 34.4- ("Acid |_Lime JAcid \ Potafs fAcid [_ Lime Now when fulphat of potafs and nitrat of lime are mixed together, a double decompofition takes place, and fulphat of lime and nitrat of potafs are formed. Let thefe two falts be mixed together ; let the quantity of fulphat of potafs be fuch, that the acid contained in it amounts to 100 ; and let a more than fufficient quan- tity of nitrat of lime be added, to faturate the fulphuric acid with lime. It is evident that for that purpofe 80,6 of lime muft be prefent; and the quantity of nitric acid combined with thefe 80,6 muft be 234,4. This quan- tity would require for faturation 195,32 of potafs, but there are only 108,7 in the mixture ; confequently there ought to exill in the mixture, after the mutual decompofition of the falts, 64,87 of nitric acid in a ftate of liberty. Such would be the refult, provided Mr Kir- wan's numbers were accurate ; but the faft is, that no fuch excefs of acid exifts in the mixture f ; and confe-f Ann.d! quently the quantity of nitric acid contained in nitrat of Ci/m. xiy. lime is ftated too high by Mr Kirwan. Although *W' therefore Mr Kirwan's tables do not coincide with the propofition which we are confidering, this is not to be confidered as a proof of its falfehood ; as there is rea- fon, from the experiment above defcribed, to fufpedt fome error in the data from which Mr Kirwan calcula- ted the ftrength of the acids. The truth of the fecond propofition may be judged of by the following Tables : Xx2 /fccording too paits of A Baryt. 646 ccord'mg to B Horafs. Sola. 127,5 56,5 148,4 74,4 194 78 RRGfJAN. Lime. Magn. 69,5 578 74,4 62,8 141,9 120,5 Amm. 42 Alum. Snip, acid Nitric acid 473 40 Mur. acid 324.7 CHEMISTRY. Part. IL Table II. ^antUy of At'id netc^tuy to Saturate 100 Affinity, Pulls of the fix Bafts. ' f-^ According to Wsnzel. 100 parts oflByryf.Potaff. Soda. Lime. Magn. Amm. Alum, Sulp. acid Nitricacid Mur. acid 120,8 92.7 83,8 79,16 60 1 19,2 67,2 51. T 96,5 55 38,8 81,7 70,2 49.7 103,9 128 147.' 259 According to Kirivan. TOO part* o\ Sulp. acid Nitricacid Mur. acid Baryt Potaf'. .So.Ij. 122,2 77.2 112 73.8 168,6 '33 Lime. 70,4 55.5 112,7 57.3 39>2 89,9 Amm. 53.3 44.8 78,5 Alum It appears that all the table of Bergman agrees with the propofitioD except the numbers which correfpoftd to fulphat of foda, fulphat of alumina, nitrat of h'me, and muriat of foda, which the late experiments of Mr Kir- wan have fufficiently {hewn to be inaccurate. Wenzel's table correfponds exaftly, except the co- lumns under ammonia and alumina, which Morveau has proved to be inaccurate. Kirwan's table correfponds exaftly, except with re- gard to the quantity of ammonia neceffary to faturate muriatic acid, which does not appear to have been ac- curately determined by experiment. Let us therefore take the truth of tbele two propo- fitions for granted, and let us confidcr every deviation from them as an error ; and let us lee whether they will enable us to difcover the abfolute affinity of fal- phuric, nitric, and muriatic acids, for their refpeftive bafes- Table I. family ef Bafe neceffary to Saturate 100 Parts of the three Acids. 100 parts Bar) t. 233.3 258,4 324,7 Poial.-. 123,3 148,4 188,8 , Soda. 78,7 95.6 126,1 Lime. 68,3 74.4 1 r6,7 Ma>;n. 56,8 62,8 97 '3 Amm. 49.3 54.8 78,5 Sulph. acid Nitric acid IVIuriat. acid lOo pans Sul[-1.. acid. Niinc at id. Mur. acid. Barytes 42,8 38,7 30.8 Potafs 81 64 52.9 Soda 126,7 101,4 79 Lime 145.7 134.4 87.5 Mngnefia 176,2 139.25 105,4 Ammonia 202,6 182,4 127,25 The firft of thcfe tables reprefents the affinity be- tween the fame acid and its various bafes ; and the ie- cond that of the bafes for the different acids. If it were required to know the ratios of the affinity which diffe- rent bafes have for any particular acid, the firll table, fuppofing it accurate, would give it exadlly. In like manner, if it were required to know the ratios of the affinity of the acids for the various bafes, we would find them in the fecond table. - But if we wifhed to know what was the affinity he-Andtocen- tween one acid and bafe, compared witli that between ftruifttablef- another aeid and a different bafe; or if we wanted to of affinity, have not the relative but the abfolute affinity between two bodies — it is plain that we could not find it in either of the tables ; for the ablblute affinity muft confift of two things, the affinity which the acid has for the bafe, and the affinity which the bafe has for the acid. Now the firft table gives us the one of thcfe, and the fecond the other ; fo that in order to reprefent affinity in ab- folute numbers, the two tables mull be multiplied into one another. This was the miftake into which Mr Kir- wan fell. His method confifted merely in conftrufting a table like our firft, which (fuppofing the numbers accu- rate) gave only the affinity between the bafes and the fame acid, but left out the affinity between the different acids and the fame bafe ; confequently the different co- lumns could not be compared with each other. It is evident, however, that if the tables were multi- plied together in their prefent ftate, they could not pof. ftbly give an accurate table of affinities. For that pur- pofe, it is neceffary to put the iame number in the firfc column of each table, and then to fubftitute other num- bers in the remaining ccJumns, having the. fame ratio to^ one another with the numbers in the original columns. This is done in the following Tables : Table I. Ratios of ihi Affinity of fix Bafes for three Acids. B.irytes. PotaR 52,85 57.43 58,11 Soda. 33.73 36,98 38,81 Lime. 29.27 28,77 3J.70 Magn. 24.34 24,28 29.94 Amm. 21,12 19.59 Sulph. acid lOOjCO Nitricacid 100,00 Mur. acid 100,00 24.15 Table Part ir, ^fljnity. ry^^^^ jj_ jj^fi^^ gj- ii^^ /jfinity of three Ac'ids for Jlx Bajei. iSulph. acifi. Nitric acid. Mur. aci'. Barytcs 100,00 90,42 74.54 Potafs 100,00 79,01 65,30 Soda 1 00,00 80,03 62,35 Lime 100,00 92,24 60,05 Magnefia too, 00 90.34 59,68 Ammonia 100,00 90,02 62,77 CHEMISTRY. 349 the fubjeft, for the candour which he has difplayed, Afiiniiy. and for the new rout which he has opened to the che- ' mical philofopher. Though this problem has not hi- therto been folved, and though the difficulties which furround it are almoll infurniountablc, we may hope much from the general fenfe which is at prefciil enter- tained of its importance, and from the zeal and abili- ties of thofe philofophcrs who have particularly turned their attention to it. In the mean time, the following Table of the (Ircngth of affinities by Morveau, though the numbers be arbi- trary, will be found of very great ufe ' Table III. ylffinUy bettueen three yields and fix Bafes in AlJoJute Numbers. .' Barytes Sulph. acf: Potafs Soda Lime Magnefia Ammonia Nitric acid lOOOO 5285 3373 2927 2434 211 2 9042 4537 2969 ^(>i3 *'93 1763 Mur. acid. 7454 3794 2419 2143 1786 15 1. 5 On the fuppofitton that the two pvopofitions men- tioned above were ftriftly true, and that the numbers which we fixed upon were precifely the quantities of acid and bafe neceflary to faturate each other recipro- cally, this lail table would reprefent accurately in num- bers the ftrength of the affinities of the three acids for each of the fix bafes refpedlively. We muft acknowledge, however, that the truth of thefe propofitions has not hitherto by any means been fufficiently proved ; but a great number of faifls concur to render them exceedingly probable, and highly wor- thy of the attention of chemical philofophers. And we hope that the method propofcd by Morveau, and which had been prevloudy pradif<"d by Richter, of verifying theoretical calculations of the compofition of the falts, by mixing together two falts which n>utually decom- pofe each other, and afcertaining whether the refult correfponds with calculation, will be followed out, and that it will be the means of enfuring more accuracy than it has hitherto been poffibie to obtain. No one will fufpecl that any thing which has here been faid is meant as a reficftion on the ingenious che- inifts who have attempted to folve this molt difficult of all chemical problems, the proportion of the ingredients ■which enter into the compofition of the falts. Mr Kir- wan, in particular, is entitled to the greateft praife for the perfevering induftry with which he has profecuted Sulph. acid Nitric acid. Miiriit. acid Aceiou- acid. 28 Caib.mc acid. Barytes 66 62 36 '4 Potafs 62 58 32 26 Soda Lime 58 50 3' 25 8 54 44 24 19 12 Ammonia 46 38 21 20 4 Magnefia 50 40 22 17 6 Alumina 40 36 18 15 2(d) • Encye. MetlmJ. CA/ct. i. 773* 577 Morveau** tabic of affinity. 5. Although every chemical combination is produced - by the fame general law, yet as their phenomena vary fomewhat according to circumftances, affinities have, for the fake of greater perfpicuity, been divided into „■ clafies. Thefe clafles may be reduced to three— Jhtiple,-^]^^^^ compound, and difpoftng affinities. claffcsofaf?- The^/y? clafs comprehends all thofe cafes in which finity, ox\\y two bodies combine together; as, for in (lance, ful-„. ""^ , u ■ J 4 .1- J u T-u a: Viz. fimple pnuric acid ana potals, oxygen and carbon. 1 he am-.g^^jiy. iiities which belong to this clafs are known by the name oi fimple oT Jingle ajjinities. Although one ot the fub-- fta net's to be combined happens to be already united with another body, the combination is lliU reckoned a cafe of fingle affinity. Thus (uppofe the iulphuric acid previoufly co-xbined with magnefia, and forming with it the fait c:.'\tAj'ulphiit of magnefia, as icon as potafs is- prefented, the acid leaves the earth (which is precipi- tated), and unites with the alkali. Even when three bodies combine, it often happens that the union is pro- duced merely by fingle affinity. Thus, when fomc pot- afs is dropped into tartarous acid, part of the acid unites with the alkali, and forms tartrite of potafs ; after this the remainder of the acid combines with the tar- trite juft formed, and compofes a new lalt known by the name of acidulous tartrite of potcfs, or tartar. This is evidently nothing tlfe than two inllances of fimple affinity immediately following each other. - When more than three bodies are mixed, decompo-Cnnipound fitiuns and new combinations often take place, which nfiini'y, could (d) This table, however, does not correfpond quite accurately to all the phenomena. For inftance, accord- ing to it, fulphat of barytes is not decompofed by carbonat of foda, although the contrary takes place ia faft. 350 C H E M I Affinity, could not have been produced had the bodies been pre- '~*~v~~-^ fented in a different ftate. If, for inftance, into a fo- lution of fulphat of potafa tliere be poured nitric acid, no decompofition is produced, bceaufe the fulphurio acid has a ilronger affinity for potafs than nitric acid has. For the viry fame realon, ammonia may be pour- ed into the fokition without producing any change. But if nitrat of ammonia be poured in, a decompofition inrtantly takes place, and two new bodies, fulphul of ammonia and nltiat of polafs, are formed. Such cafes of decompofition form the feconil clafs of affinities. They were called by Bergman cafes of double e/e3ive attrac- iion ; a name which is exceedingly proper when there are only four bodies concerned. But as there are often more than four, it is neceffary, as Mr Morveau has ob- ferved, to employ fome more comprehenfive term. We Ihall therefore call the affinities belonging to this clafs compound ajfinitie. (e) ; and comprehend under the term all cafes where more than three bodies are prefent, and produce combinations which would not have been formed without their united aftion. In thefe cafes the affinity of all the various bodies for each other afts, and the refulting combii..;>,on is produced by theaftion of thofe affinities wliich are ftrongeft. The manner in which thefe combinations and decompofitions take place, was firft clearly explained I y Dr Black. Let the affinity between potafs and fulphi'ric acid be =: 62; that uetween nitric acid and ammonia =: 38 ; that be- tween the fame acid and potafs =r 58 ; and that be- tween the fulphuric acid and ammonia =: 46. Now, let ua fuppofe that all thefe forces are placed fo as to draw the ends of two cylinders crofGng one another, and fixed in the middle in' this manner, Potafs. Nitric acid. (too 46 Sulph. acid — — Ammonia. 104 It is evident, that as 58 and 46 z=. 104, are greater than 62 -f- 38 ■:!: 100, they would overcome the other for- ces and {hut the cylinders. Jull fo the affinity between potafs and nitric acid, together with that between ful- phuric acid and ammonia, overcomes the affinity be- tween potafs and fulphuric acid, and that between nitric acid and ammonia, and produces new combinations. In all cafes of compound affinity, there are two kinds of affinities to be confidered ; \J}, Thofe affinities which tend to preferve the old compound, thefe Mr Kir- wan has called quiefcatt affinities ; and thofe which tend to deftroy them, which he has called divellent affinities. Thus, in the inftance above given, the affinity be- tween potafs and fulphuric acid, and that between ni- tric acid and ammonia, are quiefcent affinities, which endeavour to preferve the old compound ; and if they are ftrongeft, it is evident that no new compound can take place. On the contrary, the affinity between pot- afs and nitric acid, and that between fulphuric acid and S T R Y. Fart II, ammonia, are divellent affinities ; ard as they are in this Affinity, cafe ftrongeft, they adually deftroy the former combi. *~"~V""^ nations and form new ones. Bergman, who publiflied a great many cafes of com- pound affinities, employed to explain them a method fomewhat difterent from this. He would have rtpre- fented the above cafe in the following manner : Nitrat of Potafs. Potafs Nitric acid. Sulphat of Potafs. Nitrat of Ammonia, Sulph. acid. Ammonia. Sulphat of Ammonia. At the four corners of an imaginary fquare are placed the four fubftances, fo that one acid (hall be diagonally oppofite to another. On the right and left fide of the fquare are placed the old compounds, each on tlie fide of its own ingredients, and above and below are placed the new compounds. Mr Elliot improved this method of Bergman, by ad- ding numbers txpreffive of the affinity of the various fubftances. It is in cafes of compound affinity that the ratios of affinities, if we were pofTefled of them, would be peculiarly ufeful. For it is evident, that if we knew the ftrength of affinities in abfolute numbers, we would be able to determine before hand all the cafes of compound affinity. If we knew, for inftance, that the affinity between the muriatic acid and barytes were =: ^61, that between the fame acid and potafs =: 32 ; the affinity between potafs and carbonic acid ^ 9 ; and that between the lame acid and barytes ^ 14 ; — we would be certain, previous even to experiment, tiiat when muriat of bary- tes and carbonat of potais are mixed, a double decom- pofition would take place ; which we know from expe- riment to be actually the cafe. Muriat of Potafs. Muriat of Barytes, Muriatic acid, 36 Barytes, 32 14 46 Potafs. 9 C45, Carbonic acid. Carbonat "of Potafs. Carbonat of Barytes. Another inftance of decompofition by compound affinities. Sulphat (e) Morveau caUed them affinite par coiKOurt. pare II. Affinity. CHEMISTRY. Sulphat of Lime. Sulphat of Magnefia. 351 Sulph. acid, 54 Lime. Sulphuric ., „ acid, 50 Magnefia. Affinity. v.. ^ -a Sulpliat of Ammonia, 46 lAmraonis 38 92 44 (9a Nitric acid. Nitrat of Lime. SiUpliat of foda,^ I Soda, 100 40 (98 50 Nitric acid. Nitrat of ' magnefia. Nitrat of Ammonia. Nitrat of Soda. Suppofing Morveau's numbers exaft, it follows alfo, When a new compound is precipitated, a line bent even prior to experiment, that no decompofition takes downwards in the middle is to be placed between it and place when fulphat of lime and muriat of putafs are the fquare, as in the following fcheme : in'5":d ; Sulphat of Potafs. Sulphuric. g p f3_ J ( c , , •. J acid, / I Sulph. acid, . 62 Potafs. Sulphat of ^ 54 Lime, Lime, 20 82 Muriat 32 (86 )> of J Potafs. Muriatic \ acid. I for the quiefcent aSnIties are 86, and the divellent on- ly 82. Nor when acetite of lime and m\iviat of foda are mixed ; Acetite of Lime, Acetous acid, 25 19 Lime, I 20 45 Soda. :8 (47 Muriatic acid. Muriat ■ of Soda. becaufe the quiefcent affinities are 47, and the divellent only 45. Thefe cafes where no decompofition takes place have been called by Morv^u cafes of inverfe com- pound affinity. Morveau has propofed the following improvements in ^ _ reprefenting thefe cafes of compound affinities*. Method'. When decompofition does not take place, nothing is Ci/>».i.555.to be written above and below the fquare, as in the two laft examples. When a new compound remains diflbl- ved, a ftraight line is to be placed between it and the f"quare, as in the following fcheme. Sulphat of Barytes, 65 Barytes, 14 76 9 {74 Carbonic ' acid. Carbonat of Potafs. Carbonat of Barytes. When a new compound is fublimed, the line between it and the fquare is to be pointed upwards in the middle, thus , 1^ ,• When a new compound is partly diffolved and partly precipitated, the line placed between it and the fquare is to aflume the following (hape : , '. When it is partly diffolved and partly fublimed, the following is the line to be ufed : ' ,. The third clafs of affinities has been called by ^'^ AaAiiita^ Morveau tlifpofmg affinities, becaufe they dlfpofe fub-fing affinity, (lances to combine that would not otherwife have done it. Suppofe, for inftance, that fulphur is prefented to oxygen gas, it does not manifefl any affinity for it ; but combine it previoufly with potafs, and it unites with oxygen with avidity. Its previous union with potafs, in this cafe, d'lfpofcd it to unite with oxygen. The caufe of this curious affinity is not yet well underllood. If we confider what it was that prevented the fulphur and oxygen from combining, we fhall find that it can only be its own attraftion of cohefion, and the affinity between the oxygen and caloric which are combined. What- ever then diminifhes this attra£lion of cohefion, or of aggregation as it has been called, mull facilitate the union of different tempera- -tures to ui.ite, 352 C H E M Afiiiiity. of the fulpliur ivith oxygen. This 13 done in fome mca- '~ V— — j'lirt by tlif potp.fs. Befides, if aifinity depends upon tlie fiifiire of p:irticlc-s, it is evident that there muft be an alfinitv between the new compound and oxyj^en; but the niomeut the oxyf;eii appro;iches within a certain dillaiice •of tlie fiilpluir, it unites u-ith it, as its alfiaity is much greater for that fubllanee than for the compound. Tlie following is another iiiilance of this curious afli- nity : Sugar, as Lavoil'ur has proved, is coir.pofeJ of oxygen, hydrogen, and carbon : Now if concentrated fulphurio acid be poured upon fugar, the oxygen and hydrogen Combine, and form water, which unites with the acid, and the carbon is precipitated. In this cafe, the prefence of the acid difpoful the oxygen and hydrogen to con;biiie. In what manner this new combination is produced, it would not be eafy to explain : not by weakening the attraftion of cohefion ; for we do not fee how the acid could produce that effeft. The only ex- planation that can be given, is to fuppofe that the ful- phuric acid, when it approaches within a certain dif- tance of the oxygen and hydrogen, attrafts them ; and that this attraftion, together with the affinity between the oxygen and hydrogen, is greater than that which produces the combination between the ingredients of the fugar themfelves : the confequence of which muft ^gj be decompofitiou. Why bo- 6. We come now to one of the moft difficult quef- erior to that of afnnity; accordingly, it becomes ne- ceffarv to weaken that attraction by caloric till it be- ct)ines inferior to that of affinity. The quantity of ca- loric neceffary for this purpofe muft vary according to the fliength of the cohefion and of the affinity ; it muft j be inverfely as the affinity, and direflly as the cohelion. Wherefore, if we knew preclfely the force of the cohe- fion between the particles of any body, and of the af- finity between the particles of that body and of any other, we could eafily reduce the temperature neceffary to calculation. That caloric or temperature afts in this manner can- not be doubted, if we confider that other methods of diminifliing the attraftion of cohefion may be fubfti- tuted for it with fuccefs. A large lump of charcoal, for inftance, will not unite with oxygen at fo low a temperature as the fame charcoal will do when reduced to a very fine powder ; and charcoal will combine with oxygen at a ftlU lower temperature, if it be reduced to its integrant particles, by precipitating it from alcohol, as Dr Prieftley did by palfing the alcohol through red hot copper. And to (hew that there is nothing in the nature of oxygen and carbon which renders a high temperature neceffary for their union, if they be pre- fented to each other in different circumftances, they combine at the common temperature of the atmofphere ; for if nitric acid, at the temperature of 60°, be poured upon charcoal powder, well dried in a clofe crucible, the charcoal takes fire, owing to its combining with the oxygen of the acid * : And In fome other lituations , Pr,ufia, carbon is fo completely divided, that it is capable oi Mor^au, combining with the oxygen of the atmofphere, or, tlncyc- Mr- which is the fame thing, of catching fire at the com-. '' f^&w. mon temperature. This feems to be the cafe with it in thofe pyrophori that are formed by dillilling to dry- nefs feveral of the neutral falts which contain acetous acid -f-. Thefe obfervations are fufficient to fhew that f Morveau^ caloric is in many cafes neceffary in order to diminifh 'i'Sts only by diminifhing cohe- Con : And the reafon that it is required fo much in gafeous fubftances, and in thofe combinations into which oxygen enters, is the ftrong affinity of oxygen and the other bafes of the gafes for caloric ; for, owing to the repulfioQ which exilis between the particles of that fub- tile fubftance, an effedt is produced by adding large dofes of it, contrary to what happens in other cafes. The more of it is accumulated, the ftronger is the re- pulfion between its particles ; and therefore the more powerful is its tendency to fly off: and as this tendency ii oppofed by its affinity for the body and the cohe- lion of its particles, it mull diminilh both thefe attrac- tions. Though we have thus attempted to explain what has been always confidered as one of the moft difficult pro- blems in chemiftry, we are far from fuppofing that we have removed every difficulty. Much ilill remains to be done before the aftion of light and caloric can be fully underftood ; and there may be other agents, of whofe exillence we have not yet even conceived the idea. One difficulty ftill remains to be examined. Heat not only produces the combination of fome bodies, but alfo occaiions the decompofition of others. How does it aft in thefe cafes ? That many of thefe decompofitions are produced by decomtiofes chemical affinity, will be evident from the following ex- '""''"• amples. When fulphur and arfenic acid are expofed to heat, * f'll'ti'r- fulphuret of arfenic is formed * evidently by a kind of compound affinity. Oxygen Gas. A 584 How heat Caloric Sulphur 50 Oxygen 60 Arfenic > Arfenic Acid. Sulphuret of Arfenic. It) the fame manner, when nrtrat of potafs and bora- cic acid are expofed to heat, the nitric acid is volati- lized, and borat of potafs is left behind. S T R Y. Nitric Acid in Vapour. A Part IL Affinity. Caloric 4 Nitric acid „ ^Nitrat of ^" / Potafs. Boracic acid 55 Potafs Borat of Potafs. By the fame compound affinity boracic acid and heat decompofes muriat of foda. Muriatic Acid Gas. A Caloric 10 Muriatic acid 31 Muriat of Soda. Boracic acid 24 Soda Borat of Soda. In the fame manner, it would be cafy to explain hovr all the decompofitions by the dry -way, as it is called, are Bfoduced. Bat how comes caloric to decompofe water after ha- ving produced the union of oxygen and hydrogen ? The union, we have feen, was probably brought about by the play of oppofite affinities ; but in the feparation, caloric ieenis to aft by its peculiar power, or the re. pulfion which exilis between its particles. When ca- loric combines with an integrant particle of water, this repulfion muft feparate the component parts fomewbat from one another ; confequently it muft weaken their affinity ; for every increafe of diftance produces that ef- feft. Now let us fuppofe that the affinity between oxygen and hydrogen is 10?, and that the affinity be- tween caloric and each of thefe bodies is 50 : as foon as the particles of oxygen and hydrogen are fo far fe- parated from each other that their affinity is lefs than ioo, they will unite with caloric in preference, becaufe the fum of their affinities for caloric is equal to 100 ; confequently, whenever that takes place water will be decompofed. Hence we fee the reafon why more heat is always neceffary to produce the decompofition of bo- dies than what produced their union. Caloric poileffes another fmgular property, that of changing the compound affinities of bodies, even when it art II. C H E M I vfliiiiiy- it does not appear to enter as an ingredient. Wliatwc — "v mean will appear eviHent trom the following examples : Miiriit of ammonia, 7 (iecoir.pofo each other at the Caviionat of maynelia, J ordinar)- temperature of the atniofpheie, ami form miniat of magnelia and earboiiat of ammonia: but, on the contrary, Miiriat of msgnefia, audi decoinpofe each other at Carbonat of ammonia, J a high temperature ; for indance, at 212°. The products are muriat of ammo- nia and carbonat of magncfia *. Again, if muriat of loda and fulphat of magnefia be mixed together at a low temperature, for inilance at zero, they decompofe each other, and muriat of mag- nelia and fulphat of foda are formed ; but no decom- polition takes place at a temperature above 32°. — Mu- riat of foda, and fulphat of alumina, exhibit precilely the fame phenomena f . LalUy, fulphat of magnefia and carbonat of ammonia decompofe each other at the ordinary temperature ; but '"""•'"""■at 212" the carbonic acid flies off, and the remaining Fcurcroy, fubftances form a triple fait \ inn. de "Mm. ii .91. XVtfirum, tun, dc 'bim. li. IS. nd Grcn inn, de The lail of thefe phenomena appears owing to the affinity between carbonic acid and caloric, and the two lirll to the affinity between muriat of ammonia and ca- loric, for that fait is volatilized. It would not be fo eafy to explain the mutual decom- pofition of muriat of foda and lulphat of magnefia at a low temperature. It is probably connetted with the alterations in the dillance of the ingredients of chemical compounds, which are produced by the prefence and .. abfence of caloric. )f Count From the important part which caloric afts in chemi- tumford's cal combinations, Count Rumford has been lately indu- pinion re- ced to fufpecl that this fubtile fluid is the only agent by J^^-ng af- ^hich they are produced. That caloric is a necejfary agent in all chemical de- compofitions and new combinations, we very readily al- nity S T R Y. low ; brcaufe we know no other caufe except caloric fo -A prevent tiie particles of bodies from ad^ual contadt ; in which cale dccompofilion would be impoffible : and if this be the fenle in wliich that ingenious philofophcr aicribcs chemical combinations to caloric, we very rea- dily agree with him ; but if he fuppofes l!iat caloric is the agetit by which the particles of bodie* are brought near each other, and i\\t force by which tliey adhere to one another, we cannot help thinking that he is iniila- kon : For that bodies, chemically combined, are kept near each other by fome force, cannot poffibly be de- nied. Now, what is that force ? We have laid, after Newton, an allnulion between liij particles themfehes ; acknowledging, at the fame time, that we are 'unable to explain what that is. Count Rumford feems to fuppofe that there is no fuch thing as attraftion between the particles them- felves, but that caloric is the agent which keeps them together. If fo, how does caloric perform this office i For our part, we do not pretend to imderftand it any more than the nature of attraftion ; nor do we fee that it is poffible to render it more intelligible. But there is another queftion of Hill greater importance. What are the proofs that caloric is the only agent in all cafes of chemical combinations \ For our part, we can think of no proof that can render this opinion in the fmallelt de- gree plaufible. Has this celebrated and candid philofophef confider. ed this fubjeft with his ufual accuracy ? If heat be a body, it cannot furely be the caufe of affinity, unltfs it be pofiefTed of properties which, fo far from being pro- ved, have not even been fufpetled. On the contrary, if it be a property of matter, what property is it i If it be a peculiar motion, as Count Rumford fufpefts, we would alk if it be poffible for any motion whatever, in- dependent of attradtion, to produce the permanent union of two bodies ? 355 Part III. Of DOUBLY COMPOUND BODIES. THE bodies which confift of combinations of thofe fubftances that have been denominated compound, and which, for that reafon, we have ventured to call doubly compound bodies, may be reduced to three clalFes : Soaps, Neutral falts, Hydrofulphurets. Thefe fhall form the fubjedl of the three following Chapters ; and we fhall finifh this part of the article with iorne obfervations on cry/lallization. Chap. I. 0/Soaps. The compounds into which oils enter without de- compofition have been denominated /o/t/sj. Oils are capable of combining with alkalies, earths, and metallic oxides ; they are capable alfo of combining with fcveral of the acids. There are therefore two clalTes of foaps ; I. Alkaline, earthy, and metallic foaps, which, for the fake of brevity, we fhall call alialine foaps ; and, 2. Acid foaps. Thefe two clafTes form the fubjecl of the two following Sedlions. Sect. I. Of Alialine Soaps. As there are a great number of oils, all or moft of which are capable of combining with alkalies, earths, and oxides, it is natural to fuppofe that there are as ma- ny genera of alkaline foaps as there are oils. That there are differences in the nature of foaps correfponding to the oil which enters, into their compofition, is certain ; but thefe differences are not of lufficient importance to require very particular defcription. We fliall therefore dclcribe all the alkaline foaps together, and notice, as we go along, fome of the moll important differences re- fulting from the oily ingredients. „ I . Soap of foda, or common foap. The word foap Common C/apo, cfxray) firll occurs in the works of Pliny and Ga-hardfoapj len, and is evidently derived from the old German word fepe (g). Pliny informs us, that foap was firll difco- vered by the Gauls ; that it was compufed of tallow Y y 2 and (g) Beckmonn's Hijlory of Inventions, III. 2^^. — A fimilar word is ftill ufed by the common people of Scot- land. 35^ C H E M Alkaline and adies ; and that the German foap was reckoned the . Soaps, beft*. • Pliny Soap may be prepared by the following procefs. A )ib. xviii. quantity of the foda of commerce, which is a carbonat *• 5'- of foda, and which is often called lar'illa from the name ■Kt^yJ ^ , of a plant, by burning which it is procured in great forminij it- '^''''ntities in Spain, is pounded and mixed in a wooden vcfTel, with about a fifth part of its weight of lime, flacked and palTed through a fieve immediately before. TIpon this mixture a quantity of water is poured, con- fiderably more than what is fufficient to cover it, and allowed to remain on it for feveral hours. The lime attraAs the carbonic acid from the foda, and the water becomes ilrongly impregnated with the pure alkali. This water is then drawn off by means of a (lop-cock, and called the Jir/} ley. Its fpecific gravity (hould be about 1,200. Another quantity of water is then to be poured up- on the foda, which, after (landing two or three hours, is alfo to be drawn off by means of the ftop-cock, and called ihefecond ley. Another portion of water is poured on ; and after (landing a fufficient time, is drawn off like the other two, and called the third ley. Another portion of water may dill be poured on, in order to be certain that the whole of the foda is ditfol- ved ; and this weak ley may be put afide, and employ- ed afterwards in forming the (ird ley in fubfequent ope- rations. A quantity of oil, equal to fix times the weight of the foda ufed, is then to be put into the boiler, together with a portion of the third or -weaiejl ley, and the mix- ture mud be kept boiling, and agitated conftantly by means of a wooden inftrument. The whole of the third ley is to be added at intervals to the mixture ; and after it is confumed, the fecond ley mud be added in the fame manner. The oil becomes milky, combines with the alkali, and after fome hours it begins to acquire confidence. A little of ihe Jirjl ley is then to be added, rot forgetting to agitate the mixture conftantly. Por- tions of the firft ley are to be added at intervals ; the foapy fubdance acquires gradually greater confidency, and at lad it begins to feparate from the watery part of the mixture. A quantity of common fait is then to be added, which renders the feparation much more com- plete. The boihng is to be continued dill for two hours, and then the fire mud be withdrawn, and the li- quor mud be no longer agitated. After fome hours repofe the foap feparates completely from the watery part, and fwims upon the furface of the liquor. The watery part is then to be drawn off; and as it contains a quantity of carbonat of foda, it ought to be referved for future ufe. The fire is then to be kindled again ; and, in order to facilitate the melting of the foap, a little water, or rather weak ley, is to be added to it. As foon as it boils, the remainder of the firft ley is to be added to it at intervals. When the foap has been brought to the proper confidence, which is judged of by taking out fmall portions of it and allowing it to cool, it is to be ■withdrawn from the fire, and the watery part feparated from it as before. It is then to be heated again, and a 1 S T R Y. Partlir. little water mixed with it, that it may form a proper Alkaline palle. It is then to be poured into the veffels proper S .aps. for cooling it ; in the bottom of whicii there ou^ht to """^ ' ' be a little chalk in powder, to prevent the foap from at- taching itielf to it. In a few days the foap will have acquired fufficient confidence to be taken out, and form- ed into proper cakes ( h ). Tlie ufc of the common fait in the above procefs is to feparate the water from tiie foap ; for coiumon fait has a dronger affinity for water than foap has. Olive oil has been found to anfwer bed for making foap, and next to it perhaps tallow may be placed : but a great vaiiety of other oils may be employed fur that purpofe, as appears from the experiments of the French chemids above quoted. They found, however, that lintieed oil and whale oil were not proper for making hard foaps, though they might be employed with ad- vantage in the manufailure o( foft fonps. Whale oil has been long ufed by the Dutch for this lad pur- pofe. Soap may alfo be made without the aflidance of heat ; but in that cafe a much longer time and a larger proportion of alkali is neceffary. Manufadlurers have contrived various methods of fo-.,, 5 . n.. pnilticating ioap, or or addmg ingredients which in- cation, creafe its weight without increafing its value. The mod common fubdance ufed for that purpofe is water; which may be added in confiderable quantities, efpecial- ly to foap made with tallow (the ingredient uled in this country), without dimini(hing its confiftency. This fraud may be eafily detefted, by allowing the foap to lie for fome time expofed to the air. The water will evaporate from it, and its quantity will be difcovered- by the diminidiing of the weight of the foap. As foap fophifticated in this manner would lofe its water by be- ing kept, manufafturers, in order to prevent that, keep their foap in faturated folutions of common fait ; which do not diffolve the foap, and at the fame time, by pre- ventii.g all evaporation, preferve, or rather increafe, the weight of the foap. Meffrs Darcet, Lelievre, and Pel- letier, took two pieces equal in weight of foap fophifti. cated in this manner, and placed the one in a dry place in the open air, and the other in a faturated folution of common fait. After a month, the firft had loft ^'ao "f its weight, the- other had gained about t'j?^ parts *. •An. * Various other methods have been fallen upon to fophif- ''"'"• *"- ticatc foap ; but as they are not, we hope, generally^'' ' known, it would be doing an injury to the public to defcribe them here. g Different chemifts have analyfed foap, in order to af- proportion certain the proportions of its ingredients; but the re- ff its ingre- fult of their experiments is various, becaufe they ufed*^""'*- foap containing various quantities of water. From the experiments of Darcet, Lelievre, and Pelletitr, it ap- pears that foap newly made and expofed to fale con- tains 9,75 Oil, 1,37 Alkali, 4,87 Water. Soap is foluble both in water and in alcohol. Its properties as a detergent are too well known to require any defcription. j It (b) See the Memoir of Darcet, Lelievre, and Pelletier, in the Ann. de Chim. XIX. i^'^- Soaps. Soft foap. Part HI. C H E M Alkaline It Is decomportd by !in»c, and by compound affini- ty (i) by fiilphat of lime, nitr.it of lijiit, miiriat of litne, and probably all the falls which contain lime. 2. Soap of potafs. — Potafs may be fubttituted for fo- da in making' foap, and in that cafe precilely the fame procefs is to be followed. It is remark;>ble, that when potafs is ufed, the foap does not adume a folid form ; its confiftencc is never greater than that of hog's lard. This is what in this country is cMed foft/oiij). Its pro- perties as a detergent do not differ materially from ihofe o{ hard foap, but it is not nearly fo convenient for ufe. The alkali employed by the ancient Gauls and Ger- mans in the formation of foap was potafs: hence we lee the reafon that it is defcribtd by the Romans as an un- guent. Some perfons have rfSrmed that they knew a me- thod of making hard foap with potafs. Their method is this: After forming- the foap in the manner above defcribed, they add to it a large quantity of common fait, boil it for fome time, and the foap becomes folid when cooled in the ufual way. That this method may be praftifed with fuccefs has been afcertained by McfTrs Darcet, Lelievre, and Pelletier; but then the hard foap thus formed does not contain potafs, but foda: for when the common fait (mun'at of ioda) is added, the potais of the foap decompofes it, and combines with its muri- atic acid, while at the fame time the foda of the fait combines with the oil, and forms h:.rd foap : and the muriat of potafs formed by this double decomjiofitlon is • Ann. ite diflolved in the water, and drawn off along with it*. Chtm,z.ix. Chaptal has lately propofed to fubftitute wool in '*'■ place of oil in the making of foap. The ley is formed in the ufual maniier, and made boiling hot, and flireds of woollen cloth of any kind are gradually thrown into it ; they are foon diffolved. New portions are to be added fparingly, and the mixture is to be conilantly a- gitated. When no more cloth can be diflolved, the f UiJ. XX}. foap is madef. This foap is faid to have been tried with '7- fuccefs. It might doubtlefs be fubilitutcd for foap with advantage in feveral manufad.ures, provided it can be obtained at a cheaper rate than the foaps at prefent employed. Fifl'., too, have been lately fubflituted for oil with equal fuccefs. The only difadvanlage which foap made in this manner is liable to, is a difagreeable fmell, from which it cannot eafdy be freed. 3. Soap of ammonia. — This foap was firft particular- ly attended to by Mr Bertholltt. It may be formed by pouring carbonat of ammonia on foap of lime. A double decompofition takes place, and the foap of am- monia fwims upon the furface of the liquor in the form of an oil; or it may be formed with ftiU greater eafe by pouring a folution of muriat of ammonia into common foap diflolved in water. We have formed it often by J 'BtrihoUei, mixing cauftic ammonia and oil \. Mem. Par. It has a more pungent tafle than common foap. Water diflblves a very fmall quantity of it ; but it is eafily dilFolved in alcohol. When expofed to the air, it is gradually decompofed. 4. Soap of lime. — This foap may be formed by pour- ing lime-water into a folution of common foap. It is 59' Soap of ammonia. 1780, or i^khotjon journal., i, 170 Soap of lime. I S T R Y. 357 infoluble both in water and alcohol Carbonat of fixed Alkjline alkali decompofes it by compound affinity *. It melts Suaps. with difficulty, and requires a (Irons heat. «„, ''~~~'^, 5. boap ot magnelia. — 1 his ioap may be formed by 5^3 mixing together folutioiis of conuiion foap and fulphat S^ap of of magnelia. magnefia, It is exceedingly white. It is unftuous, dries with difTiculty, and preferves its whitenefs after deficcation. It is infoluble in boiling water. Alcohol and fixed oil didolve it in conliderable quantity. Water renders its folution in alcohol milky. A moderate heat melts it ; a tranfparent mafs is formed, flightly yellow, and very 6. Soap of alumina. — This foap may be formed by '''"'• mixing together folutioiis of alum and of common foap. qj.^'* . It is a flexible foft fubftance, which retains its fupple-n^ " " nefs and tenacity when dry. It is infoluble in alcohol, water, and oil. Heat eafily melts it, and reduces it to a beautiful tranfparent yellowifh mafs|. } Uid. 7. Soap of barytes refembles almolt exadly the foap^.-SW of lime §. ?/w^'"' 8. Soap of mercury. — This foap may be formed by 596 mixing together a folution of common foap and of cor- Of mercu. rofive muriat of mercury. The liquor becomes milky, '')'■ and the ioap of mercury is gradually precipitated. This foap is vifcid, not eafily dried, lofes its white colour when expofed to the air, and acquires a flate colour, which gradually becomes deeper, efpecially if expofed to the fun or to heat. It dilTolves very well in oil, but fparingly in alcohol. It readily becomes foft and fluid when heated II . || nu. 9. Soap of zinc — This foap maybe formed by mix- J97 ing together a folution of fulphat of zinc and of foap. °^ ^""^» ' It is of a white colour, inclining to yellow. It dries fpeedily, and becomes friable «|[. H ■'^'''• 10. Soap of cobalt. — This foap, made by mixing ni-„,-''^? , . . r 1 K 1 r ■ r i ii , , ° Of cobalt, trat ot cobalt and common foap, is of a dull leaden co- lour, and dries with difSculty, though its parts are not connefted. taa Mr BerthoUet obferved, that towards the end of the Of nickel, precipitation there fell down fome green coagula, much more confiflent than foap of cobalt. Thefe he fuppo- fed to be a foap of nickel, which is generally mixed with cobalt *- * IbiJ- I I. Soap of tin. — It may be formed by mixing com-„r'°° r -1 r 1 • r ■ • • • P Ot tin, mon ioap with a lolution er tin in nitromunatic acid. It is white. Heat does not fufe it like other metallic foaps, but decompofes it \. ^ Ibid. 12. Soap of iron. — Formed by means of fulphat of-,*°' iron. It is of a reddifh brown colour, tenacious, and ' eafily fufible. When fpread upon wood, it finks in and dries. It is eafily foluble in oil, efpecially of turpentine, t ■^^"'■ BerthoUet propofes it as a varnifhj. 13. Soap of copper. — Formed by means of fulphat of copper. It is of a green colour, has the feel of a refin, and becomes dry and brittle. Hot alcohol ren- dcrs its colour deeper, but fcarcely difiblvcs it. Ether diflblves it, liquefies it, anrirenders its colour deeper and more beautiful. It is very foluble in oils, and gives § •'^"'• them a pleafant green colour^. nt 1 ,< 14. Soap of lead. — It may be formed by means of ' acetite 60a Of copper, (i) In thiB and the following chapter, compound affinity is not taken always in its ftrifk and proper fenfe, but is applied to all thofe decompofitions in which the affinities of more than three, bodies aS, 358 C H E M I S T R Y. Alkajiiie arctite of liad. Tt is wnite, tenacious, and very adhe- ^"'l'" live wlicii heated. Wlifn filled, it is traiilparent, and * H-il> >l I becomes fomewliat yellow if the heat be incieafed* ii!J. Part III. 6^4 Ot iV.vcr, C.Oj Of gM, 1 5. Sn.ip of fdver. — It may be formed by means of nitrat of filver. It ip at fiid white, but becomes led- dllh bv expiifuvc to the air. AVIien fufed, its fur^ace btco-.res covered with a very brilhant iris; "beneath tlie furface it i? black -f. 1 6. Soap of jrold. — It is at firft white, and of the confiftcnee of cream. It gradually afliimes a dirty pur- ple colour, and adheres to the fkin fo that it is difficult to efface the impreffion J. 17. Soap of manganefe. — It is at firft white, but it afliimes iu the air a reddifli colour, owing evidently to Acid 61- UiJ. 60S Si lap of bLnzoin, i in J. 606 Ai a of lapga Cj^^g abforption of oxygen. It fpeedily dries to a liard brittle fubftance, and by liquefaction affumes a brown blackifli colour J. We owe the following refinous foaps to Mr Me- gQy zai7e. Soapcftur- ife. "Soap of turpentine and potafs. — 576 grains of pemine a^Jturpentine were diirolved in 9216 grains of alcohol, and rpotafo. then ^76 grains of potafs ucve added. The alcohol was dilb'lled off at a boiling water heat. There remain- ed in the retort 648 grains of a browiiifh foapy matter, which when fpread on glafs appeared tranfparent. There remained alio nearly the fame quantity of potafs diffol- ved in water. This foap was put in a vefFel for fix weeks ; during which time 72 grains of fulution of pot- afs feparated from it. It bad aflumed the confillence of honey. Its colour was browner. It was completely foluble in water : the folution was milky. It diffolved alfo in alcohol. It had no difagieeable tafte. Vinegar decorapofed it. 19. Soap of benzoin and potafs. — By treating 9216 grains of alcohol, 1728 grains of benzoin, and 576 grains of potals, as above, 1728 grains of a foap were obtained, browner than that of turpentine, of an odour a little aromatic. When left in a cellar for fix weeks, it became folld. Its folution in water was yellowhh. Vinegar decompofed it. This compound is the fame §3- with Starkey's foap. Of balm of 20. Soap of balm of Peru and potafs — 1152 grains Peru, of balm, 2304 grains of potafs, and 9216 grains of al- cohol, produced a foap of a reddiih colour, and pretty confiltent. 21. Soap of guaiac and potafs. — 1728 grains of guai- ac was diflblved in 18648 grains of alcohol, and the fo- lution filtered, and to this 1728 grains of potafs were added, and the foap obtained as above. It was folid, of a brown colour at firll, which afterwards became green on the furface, but remained unaltered within. Its fo- lution in water was greenifh. It had no difagreable tafte. It diflblved in alcohol, and formed a green tinfture. Vi- negar decompofed it. 2 2. Soap of fcammony and potafs. — By the above f^ammony. procefs a foap was obtained with fcammony pretty con- fiif ent, of a brown colour, foluble in water, and not de- compofed by the water of pits from which felenites is obtained. It has no difagreeable tafte. Its folution in alcohol is of a deep amber colour ||. S E c T . II . 0/ Acid Soaps. Sulphuric acid may be combined with oils in the following manner : Put two ounces of it into a glafs 610 Of gbaiac, 611 And of 11 Jtar. dc FhyJ. XV. 4+1- 6il Method of foi mir\^ »cid foaps. mortar, and add, by little and little, three ounces of the oil nearly boiling hot, triturating it coiiftantly. A fub- llani-e is obtained of the confiftence of turpentine. Dif- folvc it in about fix ounces of boiling water, and the f wliice, opaque, vifcld ; frothes. Solution in alcohol tranfparent and brown. Potafs, ammonia, magnefia, nitric acid, muriatic acid, vinegar, nitre, fal ammoniac, acetite of lead and white oxide of lead, decompofe it. g , 4. Soap of fulphuric acid and butter of cocao. — It is Of butter hard, and marbled like Venice foap. Solution in waterof cocao, grey, ojiaque, vifcid; frothes. Solution in alcohol yel- low and tranfparent. Potafs, ammonia, nitric, muriatic, and acetous acids, tartar, lal ammoniac, tartrite of pot- afs, acetite of lead, and zinc in powder, decompofe it. When diftilled, there came over water, an oil that coa- gulated, and a few drops of a black oil, which alfo con- gealed : both were rancid. gj. 5. Soap of fulphuric acid and virax. — It is white, and of wax, becomes very hard. Its folution in water is white, and opaque, aid frothes: Its folution in alcohol is yellow and tranfparent. Potafs, ammonia, nitric and muriatic acids, decompofe it. g,g 6. Soap of fulphuric acid and fpermaceti. — It isOf fperma. brown. It diffolves in water: the folution is milky, "'■> vifcid, and frothes on agitation. It diffolves in alcohol ; the folution is tranfparent and yellow. It is decompo- fed by as much alkali as iaturates the acid : if more be added, it unites with the oil, and forms a new foap. Lime and magnefia decompofe it. The oil is alfo fe- parated, and appears in the form of a coagulum on add- ing to the folution nitric acid, muriatic acid, tartar, nitre, nitrat of foda, common fait, and zinc in powder; but not on adding vinegar, tin, lead. 6ij 7. Soap of fulphuric acid and oil of eggs. — Its folution Of oil <^ in water is white, opaque, vifcid; frothes : that in alco-"^88'' hoi yellow and tranfparent. Alkalies decompofe it ; but if too much be added a new foap is formed. Nitric and muriatic acids feparate the oil of the confiftence of wax, Part III. CHEMISTRY. 359 Neutril Salts. 670 Of turpen- :iiie, 6ii Ard of am. ber oil. * Jnrn. ic ftyf.xsi. \°9- wax, the firft yellow, the !ail a deep brown. Nitre, fal ammoniac, acetite of lead, iron iilings, zinc powder, decompofe it ; vinegar, borax, iilings of lead do not. To unite this acid with the efTtntial oils, three ounces were put into a glafs mortar, and four ounces of the oil were added drop by drop, and care taken to pre- vent Its becoming hot : equal parts of water were then poured on, and the whole heated flowly nearly to the temperature of boiling water : on cooling, the foap united into a brown mafs. 8. Soap of fulphuric acid and turpentine. It is brown, and of the confitlence of foft wax. Its folution in wa- ter is grey, opaque, vifcid ; frothes : Its folution in al- cohol IS brown and tranfparent. Alkalies decompofe it : with too much it forms at the boiling heat a new foap. Nitric and muriatic acids feparated the oil thicken- ed, as did alio white oxide of lead, muriat of lead, mu- Tiat of foda and iron filings ; but acetous acid, boracic acid, tartrite of potafs, and tin iilings, produced no fuch effeft. p. Soap of fulphuric acid and amber oil. — Its folution in water and alcohol as in the laft foap. Alkalies, mag- nefia, and lime, decompofed it. Nitric and muriatic acids feparated the oil of the confiftence of wax. Tartar, fal ammoniac, muriat of antimony, acetite of lead, iron iilings, decompofed it ; vinegar, acetite of ammonia,, and lead did not. Mr Achard, to whom we owe thefe foaps *, could not fucceed in his attempts to form foaps with nitric and muriatic acids. < Chap. II. 0/" Neutral Salts. 6l% Salt ex- lUincd. The -worAJalt has been ufed in chemiftry in a very extenfive, and not very detinite fenfe. Every body which is fapid, eafily melted, foluble in. water, and not combullible, has been called z fait. Salts were confidered by the older chemifts as a clafs of bodies intermediate between earths and water. Many difpiites arofe about what bo.lies ought to be compre- liended under this clafs, and what ought to be excluded from it. Acids and alkalies were allowed by all to be falts ; but the difficulty was to determine concerning earths and metals. Several of the earths poflefs all the properties which have been afcribed to falts ; and the metals are capable of entering into combinations which poiTcfs faline properties. It is needlefs for us to enter into this difpute at prefent, as we have taken, the liber- ty, in imitation of fome of the bell modern chemifts, to expunge the clafs of falts altogether, and to arrange thofe i'ubordinate claffes, which are ufually referred to J,, it, under diftinft heads, ftutralfalt The word neutral fait was originally applied exclu- iflained. furely to combinations of acids and alkalies, which were confidered as fubftances poffeffing neither the properties of acids nor alkalies, but properties intermediate between the two. But the word is now always taken in a more extenfive fenfe, and fignifies all compounds formed by the combination of acids with alkalies, earths, or metal- lic oxides. In thefe compounds, the earth, alkali, or oxide, is denominated the lafe. Each order of falts is denominated after the acid which enters into its compo- Su!phats. fition ; and every individual fait is dillinguilhed by fub- >'"'"" joining the name of its bafe. Tluis all the falts into which fulphuric acid enters arc calkdyu.y'/«/j, and the fait formed by the combination of fulphuric acid and potafs is c^Wt:A fulphat of potafs. It is evident, then, that there muft be as many orders of- neutral falts as there are acids ; and as many falts in each order as there are alkalies, earths, and metallic oxides,- fuppofing every acid capable of combining with every one of thefe fubftances. But befidcs thefe fimple com- binations of one acid and one bafe, there are others more complex, compofed of two acids combined with one bafe, or two bafes combined with one acid, or a neutral fait combined with an acid or a bafe. Thefe combina- tions have been called triple falts ; and they increafe the number of neutral falts very confiderably. In the following feftions we (hall take a (hort view of the properties of the principal neutral falls at pre- fent known ; for this wide and important region of che- miftry is Itill very far from being completely explored. Sect. I. Of Sulphats. Sulphuric acid is capable of combining with all the alkalies, with alkaline earths, alumina, jargonia, and the greater number of the metallic oxides. The prin- cipal neutral falts which it forms are as follows : 6,4 I. Sulphat of potafs. — This fait may be formed byS.lphatof. faturating diluted potafs with fulphuric acid, and theuf'-'f'- evaporating the folution gently till cryftals are formed. It feems to have been known at a very early period by chemills, and a great variety of names were given to it, according to the manner of forming it, or the fancy of the operator. Some of thefe names were, fpecijicum purgans, tiitrum fxum, arcanum duplkatum, panacea bol- fatica, fal de duohus, fal polychrtjl glafcri, &c. ; but it was commonly known by the name of vitrhlatfd tartar till the French chemifts called 'w fvlphal of potafs-, when they.fnrmed their new nomenclature in 1787 (k). g When the folution of fulpliat of potafs is fufficiently itsjironer-.' diluted, it affords by evaporation hexahedral pyramios, tits. or fliort hexangular prilms, terminated by one or more htxangular pyramids. But tiiefc cryftals vary much in their figure, according to the care with which they are prepared. It has a very difagreeable bitter tafte. Its fpecific ' gravity is 2,298*. _ _ * griffon. It is foluble in the temperature of GoP m 16 times its weight of water ; in a boiling heat, it is foluble in 5 times its weight f. ^ Scr^man, - According to Bergman, it is compofed of 40 parts of acid, 52 parts of alkali, and 8 of water; but accord- ing to Kirwan, whofe experiment has been already de- Icribed, it is compofed of 45 parts of acid and 55 of alkali.. It fuffers no alteration in the air. When placed upon burning coals, it breaks into pieces with a noife rcfembiing a number of imall explo- fions fucceeding each other at fliort intervals ( l), but fuffers no other alteration. In a red heat it melts. It has hitherto been applied to little ufe. It is a purgative. ( K ) Bergman called it allali •uegetah'tlt vitriolalam^ and Morveau vitriol of potafs. (l) This is called decrepitation. C H E M I purgative, but I'n difugreeable ta.le prevents it from being much employed for that purpofe. It often has aii excefs of acid, owing, as Mr Berg- man and Morveau have very ingenioully explained, to an affinity which exids between this fait and fulphuric acid. It is decompofed by compound affinity by the f(jl. lowing; falts : • Xlrxvan. J Bergman. § /t of fait was difcovered by Mr Fourcroy. Into the folution^"*""""'" of 100 parts of fulphat of magnefia in 500 parts of wa-nenaT*^* ter, 12 parts of ammonia being poured, a very fmall quantity of magnefia was precipitated, and a confider- able quantity more on the addition of another dole of ammonia; but farther additions had no effeft. From the magnefia precipitated, it appeared that 38 pans of the fulphat had been decompofed. There remained, therefore, 62 parts in folution, mixed with a large quan- tity of ammonia. By evaporation, 92 parts of a white tranfparent rhomboidal fait were obtained, evidently compofed of fulphuric acid, ammonia, and magnefia, in the proportions that would have formed 62 parts of fuU phat of magnefia and 30 of fulphat cf ammonia, and probably confifting of a combination of thefe two ful- phatsf. ^^nn.Ji 9. Sulphat of alumina. This fait m.ay be formed hyCNm. iv. diffblving alumina in fulphuric acid. It has an ailrin-*"; gent tafte, is very foluble in water, and cryftallizes in SulphL of thin plates which have veiy little confil'a-ncef . Little aliimira. attention has hitherto been paid to this fait, which was* ^'"u^'i'^'it never properly diftlnguilhed from alu?n till two memoirs, f""'"' -, one by Vauquellu and another by Chaptal, on the na- aj^^and"* ture of alum, made their appearance in the 22d volume Ch.iptal, of the Annates de Chimie. This fait generally contains'*"'- **+• an excefs of acid, and is not neutralized without con- fiderable difficulty J . ( UtJ. p. 10. Sulphat of alumina and potafs, or alum. The*^"^" , trrurr.pi^ of the Greeks, and the alumen of the Romans, ^iJn,^ was a native fubftance, which appears to have been nearly related to grnn iiitriol or fulphat of iron ; and which confequently was very different from what we at prefent denominate alum. From the refcarchcs of Pro- feffor Beckmann, it appears that we owe the difcoveiy of alum to the Afiatics ; but at what period, or by what means, the difcovery was made, is altogether un- known. It continued to be imported from the Eaft till the I ^th century, when a number of alum works were efta- bliihed in Italy. In the 16th century it was manufac- tured in Germany and Spain ; and durliig,Queen Eli- zabeth's reign an alum work was eftabliftied in England by Thomas Chalomer. The alum of commerce is ufually obtained from earths containing fulphur and clay, or fulphuric acid and clay. The compofition of alum has been but lately under- its compo- Z z ftoodCtion, (?) Only below the temperature of 32". Scheele, Gren, ./inn. de Chitn. xxiii. (cl) Only below the temperature of 2ia°. Fourcroy^ jhid. ii. 791. 362 CHEMISTRY. Sulphats. ftood with accuracy. It has been long known, indeed, ' that one of its ingredients is fiilphurie acld(R) ; and the experiments of GeofTroy, Hellot, Pot, Margraf, and Maoquer, proved inconteftibly that alumina is an- other ingredient. But fulphuric acid and alumina are incapable of forming alum : Mjnufafturers knew, that iHt addition of a quantity of potafs, or of ammonia, or of fome fubllance containing thefe alkalies, is almoft al- ways neccfiary ; and it was proved, that in every cafe in which fuch additions are iinnecefTary, the earth from which the alum is obtained contained already a quan- tity of potafs. Various conjectures were made about the part which potafs afts in this cafe; but Chaptal and Vauquelin appear to have been the firft chemifts that afcertained, by decifive experiments, that alum was a triple fait, compiled of fulphat of alumina and of pot- 638 afs united together (s) And pro- Alum crylUllizes in large oftahedrons, compofed of perries. ^^^^ tetrahedral jvyraiiiids^ applied to each other at their bafes. It has a fweetifh and aflringent tafte, and always red- dens the tincture of turnfole. • N!umann j^ j^ foUible at the temperature of 60°, in from 1 o * r^/>Tr^^'''to 15 t t™fs its own weight of water, according to its vid Chaptal.-^anty ; pure alum being mod infoluble. Seventy-five :J Bergman, pgrts of boiling-water diffolve 100 of alum J. A hundred parts of alum contain, according to Kir- , r, . wan, 17,62 parts of acid, 18 of earth (and alkali), and i^/B ii.14. 64,38 of water ^. When expofed to the air it efflorefces (lightly. When expofed to a gentle heat it undergoes the wa- tery fufion. A ftrong heat caufes it to fwell and foam, and to lofe about 4.4 per cent, of its weight, confiiting l^iii- (.(jiefly of water of cryftallizationll. What remains is called calcined or burnt alum, and is fometimes ufed as a corrofive. / " Alum is of great importance as a mordant in dyeing, and is ufed alfo in feveral other arts. By compound affinity it is decompofed by the fol- lowing falts. Partlir. Homberg'fr ryropho- Nitr^ of foda, . lime, ammonia, magncfid, Muriat of barytes, . potafs, foda, lime, - ammonia, ■ magnelia, Acetite of barytes, Acetite of potafs, foda, . . . lime, ammonia, magnefia, Carbonat of barytts, potafs, - ■ foda, lime, — — — — — ammonia, macrnefia. If three parts of alum and one of flour or fugar be melted together in an iron ladle, and the mixture dried Suljihatj. till it becomes blackifh and ceafes to fwell ; if it be *— -v— ' then pounded fmall, put into a glafs phial, and placed in a fand-bath till a blue flame iffues from the mouth of the phial, and after burning for a minute or two be al- lowed to coo1(t), a fubllance is obtained known by the name of Homberg's pyrophorus, which has the property of catching fire whenever it is expofed to the open air, efpecially if the air be moift. This fubftance was accidentally difcovered by Hom- berg about the beginning of the 18th century, while he was engaged in his experiments on the human fieces. He had dillilled a mixture of human fgeces and alum till he could obtain nothing more from it by means of heat ; and four or five days after, while he was taking the refiduum out of the retort, he was furprifed to fee it take fire fpontaneoufly. Soon after Lemery the Young- er difcovered that honey, fugar, flour, or almoft any animal or vegetable matter, could befubftituted for hu- man fzeces ; and afterwards Mr Lcjoy de Suvigny fliew- ed that feveral other falts containing fulphuric acid might be fubilituted for alum *. Scheele proved, that * See Af^r. alum deprived of potafs was incapable of finrming py. ?""■'' C/a. rophorus, and that fulphat of potafs might be fubilitu- ted for alum \. And Mr Prouft has fliewn, that a num-f Scheeli on ber of neutral falts, compofed of vegetable acids andal-^""'- ""^ '* kalies, or earths, when diftlUed by a fl^rong fire in a ^e- J"'"'^*'"''"' tort, left a refiduum which took fire fpontaneoufly on expofure to the air. Thefe facts have thrown a great deal of light on the nature of Homberg's pyrophorus, and enabled us in fome meafure to acjou'nt for its fpontaneous inflamma- tion. It has been afcertained, that part of the fulphu- ric acid is decompofed during the formation of the py- rophorus, and of courfe a part of the alkaline bafe be- comes uncombined with acid, and the carbon, which gives ii its black colour, is evidently divided into very minute particles. It has been afcertained, that during the combuflion of the pyrophorus a quantity of oxygen is abforbed. The inflammation feems to be owing to a d'ljpofng ajintty. Part of the carbon and of the fulphur attraft oxygen from the atmofphere, in order to com- bine with the potafs, and the caloric difengaged pro- duces a temperature fufhciently high to kindle the reft of the carbon. Alum is capable of combining with alumina, and of forming what has been called alum faturated 'with its earth, which is an infoluble, taftelefs, earthy-like fub- llance. It is capable alfo, as Chaptal informs us, of combi- ning with feveral other bafes, and of forming many triple falts, which have never yet been examined with attention %. f ^„„. a II. SulphatCAiw. uii, J93. (r.) Rome chemifts have thought proper to call the fulphuric acid, obtained by diftilling alum.^inV of alum. (s) This they did in the two memoirs above quoted, and which were firft publiflied in the 22d volume of the Annales deChimie. An account of Vauq\ielin's memoir has been already given under the article Alum in this Subbhmint. Chaptal's memoir is no lefs interelting. This celebrated chemift appears, from the fafts ftated in the 2?d volume of the Annales, p. 222. to have made his difcovery before Vauquelin : who, however, was igno- rant of what Chaptal had done, as he informs us in the Jnn. de Chiin. xxv. 107. that his paper was read to the Inftitute a fortnight before that of Chaptal's came to Paris. He informs us, too, that Defcroifilles bad long be- fore made the fame difcovery, and that he had publiflied it in BerthoUet's Jrt de la Teinlure. (t) Care mull be taken not to keep it too long espoftd to the heat. Part III. C H E M Sulpliao. 640 Su phat of jargonia. ♦ yatiguc' lln, An:!' •/« Cbia. xxii. 199- f Jour. Jc fhyf. XXXvi. 187. 641 Green ful- (ihaiof irunc ) Lit. ixxiv c. I]. j Bergman, II. Sulphat fif jargonia (u). In order to combine 'jargonia with acids, they fliould be poured upon it while it is yet moilt, after being precipitated from fome of its folvents ; for after it is dry, acids do not aCt upon it without difficulty. By this method fulphat of jarjTo- nia is eafdy formed. It is white, and without fenfiblc tafte. Heat expels the acid from it, and the jargonia remains in a ftate of purity. At a high temperature charcoal converts it into a fulphuret, which is foluble in water, and which, by evaporation, furnifhes cryrtals of hydrofulphuret (t) of jargonia*. Klaproth informs us, that with excefs of acid ful- phat of jargonia forms tranfparent ftelllform cryllals, fo- luble in water, and having an afhingent talle \. I 2. Sulphat of iron. There are two fulphats of iron, which were firll accurately dlllinguiflied by Mr Prouft. The one contaixis the green oxide, the other the red oxide of iron. We fliall, in imitation of Mr Prouft, de- nominate them from their colours. The green fulphat of iron. — This fait, which is com- ■pofed of fulphuric acid and green oxide of iron, is found native, and was known to the ancients. It is mention- ,ed by Pliny under the names of mify,fory, calchantum \. It was formerly called green vitriol. It is generally prepared by expofmg native fulphuret of iron, a vei-y abundant mineral, to air and moifture. Its cryftals are of a light green colour, and in the form of rhomboidal parallelopipeds. It has a Iharp aftringent talle. It is foluble in fix times its weight of water at the temperature of 60°, and in |ths of its weight of boil- ing water ^. It is infoluble in alcohol. According to Bergman, it is compofed of 39 parts I S T 11 Y. 36J of acid, 2^ of oxide, and 38 of water; but according Sulihati. to Mr Kirwan, of 26 parti of acid, 28 (u) of oxide, ——r-"-' and 46 of water. When expofcd to the air, it efflorefccs ; but if it be moillened, it is gradually converted into red fulphat of iron. When heated, it firft aflTumes a yellow colour, lofes its water and its acid ; if the heat be increafed, no- thing remains but a yellow powder. Tlie Pruflic alkali precijiitates from the folution of this fait a white powder, which gradually becomes blue by attrafting oxygen *. » Preu/t. It is ufed in dyeing, and in making ink, &c. It is decompofed by compound affinity by Nitrat of filver, Muriat of foda f . ^ b„//^„ ^/ij The rfj fuj[that of iron may be formed by expofing Tutlitn, a folution of green fulphat to the air, or by treating it 'f'"'- '''^. with nitric acid. It was formerly called mother ivater of vitriol. 641 Little is known of its properties, except that it isRedfiiliiliat deliquefcent, incryftallizable, and foluble in alcohol. «iiron. It was firft accurately examined by Mr Proult. The green fulphat of iron generally contains fome of it, which may be feparated by means of alcohol. It is alone capable of forming Pruflian bli;t with the Pruffic acid, and of ftriking a black colour with the gallic acid J. t See We have obferved, that when it is diluted with w^-Vroufl's p,i. ter, and an excefs of fulphuric acid is poured iji again flowly converted into green iulphat. 13. Sulphat of zinc. — This fait, according to the 64) beft accounts, was difcovered at Rammelfberg in Ger-Sulphat of many, about the middle of the 16th century. Many^'"'* Z z 2 afcribe u isf , „ "I, Nuhul. 435- (u) jfargotiia, or, as the French chemifts call it, xirconia, has been difcovered in great abundance in France by Morveau, who found that the hyacinths of Expailly contained more than half their weight of it. From Vau- quelin's analyfis they appear to be compofed of 3 2 parts of filica, ' 64 jargonia, 2 oxide of iron. Jargonia has been examined with great care by thefe two philofophers, the experiments of Klaproth have been confirmed, and feveral new properties of it have been difcovered. Perhaps a more detailed account than we have hitherto given of this new earth may not be unacceptable to our readers. Jargonia is a white powder, its fpecific gravity is confiderable, it has a feel refembling that of filica, it has no tafte, and is infoluble in water. When feparated from its folutions by pure alkalies, it retains, when expofed to the air to dry, a pretty confiderable quantity of water, which renders it tranfparent, and gives it a refemblance to gum arabic both in its colour and frafture. When expofed to the heat of the blow-pipe it does not melt ; but Vauquelin melted it by expofing it furround- ed with charcoal in a porcelain crucible to an intenfe heat for an hour and a half. Its fpecific gravity was then 4,35, its colour was grey, and its hardnefs fuch that it was capable of fcratching glafs. It melts with borax, and forms a tranfparent and colourlefs glafs ; but pholphat of foda and the fixed alkalies do not attack it. It is infoluble in the fixed alkalies, has very little affinity for carbonic acid, and is precipitated from its folu- tions together with iron by the Pruffic alkali. Its affinities, as far as they have been afcertained by Vauquelin, are as follows : Vegetable acids, order unknown, Sulphuric acid. Muriatic, Nitric. See upon this fubjeft the Memoirs of Morveau and Vauquelin, j4nn, de Chim. xxi. 72. and xxii. 179. (t) Thefe curious falts form the fubject of the next chapter. (u) Perhaps the quantity of oxide is fomewhat over-rated here ; for before it was examined by Mr Kirwan, it' had afTumed a red colour : it muft therefore have been converted into the brown or red oxide by attracting oxy- gen from the atmofphere. CHEMISTRY. mann's HiJ}. of Inven~ thns, art. + Btrgman, t UiJ. 644 Sulphat of maiiganefe. § SchieU, 645 Sulphat of nickel. ^ "Bergmanj ii. 16S. 646 Sulphat of cobalt. 647 Sulphat of lead. * Monntt. 648 Sulphat cf copper. afcribe the invention to Julius Duke of Brunfwick. Hciikel and Neumann were the firfl chemitb who proved that it contained zinc ; and Brandt firft. afcer- tained its compofition completely *. It is generally formed for commercial purpofes from fulphurct of zinc or blir.de, as it is called. This fait is called alfo ivhhe vitriol. It is of a white colour, and its cryftals are rhomboi- dal prifms, terminated by quadrangular pyramids : there is generally a flight defeA in two of the oppofite an- gles of the prifm, which produces a quadrangular fec- tion f. Its fpecific gravity is 2,000. It has a (harp ftyptic tafte. It is foluble in 2,28 parts of water at the tempera- ture of 60" ; but in a much fmaller quantity of boiling water J. It is compofed, according to Bergman, of 40 (v) parts of acid, 20 of oxide, and 40 of water : Kirwan fuppofes that it is compofed of iz parts of acid, 26,4 of zinc, 20 of oxide, 4 T, 6 of water (wj. According to Bergman, this fait is not altered in the air; others affirm that it efflorefces. This, no doubt, depends upon the place where it is kept. Heat decompofes this fait. 14. Sulphat of manganefe. — This fait was firft ob- tained by Scheele (x) ; It is compofed of fulphuric acid and white oxide of manganefe. Its cryftals are oblique parallelepipeds ; they are of a white colour, and very bitter J. Thefe cryftals are decompofed by a ftrong red heat, and the fulphuric is converted into fulphurous acid by the oxide attrafting its oxygen, and being changed into black oxide ||. 15. Sulphat of nickel This fait, which is compo- fed of fulphuric acid and oxide of nickel, was firft de- fcrib«d by Bergman. Its cryftals are in the form of decahedrons, compofed of two quadrangular truncated pyramids ; they are of a green colour ^. I 6. Sulphat of cobalt. — This fait was firft mentioned by Mr Brandt. Its cryftals are of a reddifli colour; but if any nickel be prefent, they are green. 17. Sulphat of lead. — This fait has been long known: it is compofed of fulphuric acid and white uxide of lead. The cryftals are white, fmall, and moft commonly needle- fhaped: according to Sage, they are tetrahedral prilms. It is foluble in 18 parts of water. Heat decompofes it. — It is very cauftic. 18. Sulphat of tin. — Nothing is known concerning this fait, except that it cryftallizes in fine needles inter- laced with one another*. 19. Sulphat of copper. — This fait appears to have been known to the ancients. It is generally obtained by evaporating thofe waters which naturally contain it. It is called ullo l/ue •vitriol. Its cryftals are of a deep blue colour; they are in the form of oblong rhomboids. Its fpecific, gravity is 2,230. It has a very ftrong ftyptic tafte ; and indeed is em- ployed as a cauftic. It is foluble in four parts of water at the tempera- I S T R Y. Part lir» ture of 60° ; but in a much fmaller quantity of boiling Sulphats. water *. ' " ' It is coinpofed, according to Bergman, of 46 parts "S'"'"' of acid, 26 of oxide of copper, and 28 of water. Kir. wan fuppofes it to contain 27,68 of acid, 35 of oxide, and ■?7,32 of water f. t Mlntr.i'u When expofed to the air, it efflorefces, and is cover. ^J- ed with a yellowifti grey powder. It requires a very ftrong heat to decompofe it. It has the property of communicating a green co- lour to flame. It is ufed in the preparation of feveral paints, and for a variety of other purpofes. It is decompofed by compound affinity by acetite of lead. • , 20. Sulphat of bifmuth. — Little is known of this <;y| [,', ^j fait, except that it is with difficulty cryftallized, and is bifmuth, very dehquefcent. ^.^ 2 1. Sulphat of antimony. — This fait does not cry- Antimony, ftallize. It is eafily decompofed by heat. , 22. Sulphat of arfenic. — This fait is fcarcely known. Arfenic It does not appear to be cryftallizable. It is decom- pofed by water. ^^ 23. White fulphat of mercury. — This fait may be wiiite fuU formed by boiling together two parts of mercury andphatof three of concentrated fulphuric acid, and rtop')ing the "'ercury. procefs whenever the mercury is converted into a white mafs. This mafs, in order to remove the excefs of acid, is to be w^died repeatedly with fmall portions of water, till it ceafes to redden turnfole. The fulphat of mercury, thus obtained, is very white. Its cryftals ave either fmall plates or prifms. Its tafte is not very cauf- tic. It is foluble in 500 parts of water at the tempe- rature of 55°, and in 287 parts of boiling water. It is compofed of 8 ^ parts of white oxide of mercury, 12 of fulphuric acid, and 5 of water J. It is not altered { Fswwoj. by expofure to the air. Heat decompofes ft. ■^'"'- <^i This fulphat is capable of combining with a new ''• portion of acid : It was in that ftate before it was wafti- ed with water. This fait, which may be called acidu- lous white fulphat of mercury, has a very cauftic tafte, and is corrofive. It reddens vegetable blues. It is foluble in 1 57 parts of water at the temperature of 55% and in 33 parts of boiling water {. _ j Fourcroy, 24. Yellow fulphat of mercury. — This fait may be/'foV. obtained by continuing to boil the preceding mixture of ^ii mercury and fulphuric acid till the mercury aftumes a yel- 1" °^ low colour. It appears to be compofed of yellow oxide merci of mercury and a fmall portion of fulphuric acid. It is foluble in 2000 parts of water at the temperature of 51;°, and in 600 parts of boiling water. The folution is colourlefs. It was formerly called turliih mineral ]| . || Fourcrty, 25. Sulphat of ammonia and mercury. — This triplci'V. fait may be formed by pouring ammonia into a folution , ^|^4 ^ of fulphat of mercury. If only a fmall quantity of am- jj^P^^^^;"' monia be ufed, a copious blackilh precipitate takes j^d mer-. place, part of which is converted into running mercury cury. Ijy expofure to light ; and confequently is black oxide of mercury ; the remaining part is the triple fait. If a large quantity of ammonia be ufed, only the black oxide is :of - mercury. (v) There is evidently fome miftake in this ftatement ; it does not correfpond with what he fays elfewhere. (w) Mineralogy, ii. 24. We do not underftand this ftatement. (x) Weftfield, indeed, obtained it ; but he miftook it for fulphat of magnefia. part in. CHEMISTRY. ^Strgir. 656 Sulphat of urauium. 6^7 Titanium, Sulphats. I's precipitated ; for the triple fait 13 rendered much •■"■"v^""^ more foliible by an exccfs of ammonia. As this exeefs evaporates, the fait cryllallizes. The cry Hals are poly- gons, very brilliant and hard. It has a Iharp, aultcre, metallic tafte. It has no peculiar odour. It is fcarcely foluble, except with excels of ammonia. It is compo- fed, according to Fourcroy's analyiis, of 18 parts of fulphuric acid, 33 of ammonia, and 39 of oxide of mer- cury. Heat decompjfes it. The produfts obtained by dillilling it are, a little ammonia, azotic gas, a little pure mercury, fome fulphite of ammonia ; and there re- • Fcunro); mains yellow fulphat of mercury *. iiU. This triple f It may- be formed alfo by pouring am- monia upon acidulous lulphat of mercury, or on yellow \ liiJ. fulphat of mercury f. *?5 26. Snlphat of fdver. — This f.ilt Is formed by pour- Siilj hat of ju^ fulphuric acid on o^ide of lilver. Its crylLals are fmall needles. It mtlts when expofed to a llrong heat, but does not fublime. It is dccompofed by niuriat of lead J. 27. Sulphat of gold. — This fait is unknown. 28. Sulphat of platinum. — Unknown. 20. Sulphat of tungllen. — Probably no fucli combi- nation is poflible. 30. Sulphat of molybdenum — Probably impoffible. 31. Sulphat of uranium This fait was firll formed by Mr Klaproth. He formed it by pouring fulphuric acid on the oxide of uranium. Nothing farther is known of it, except that its cryftals are fmall, and of a ytUow colour. 32. Sulphat of titanium. — This fait was firfl formed by MrM'Gregor. It does not appear, from Klaproth's - „ experiments, to be crylfallizable. Tellurium. 33- Sulphat of tellurium. — When one part of tellu- rium is mixed cold in a well-ftopped vcffelwith a hun- dred parts of concentrated fulphuric acid, the latter gradually affumes a beautiful crimfon red colour : when a fmall quantity of water is added, drop by drop, the colour difappears, and the metal is precipitated in the form of black flakes. The folution is deftroyed by heat, the colour difappears, and the metal feparates in the ftate of a white oxide. When fulphuric acid is di- luted with two or three parts of water, and a fmall quantity of nitric acid is added, it diffolves a confider- able quantity of tellurium. The folution is tranfparent and colourlcfs, and is not decompofed by the addition 5 Xlafirotl, of a larger quantity of water j . Mag.i.%0. Sect. 11. Of Sulphites. Salts compofed of fulphurous acid united refpec- tively with alkalies, earths, or oxides, are calledyii^^i/fj-. Thofe hitherto examined are the following : Sulphite of '■ Sulphite of potafs. — This fait was firlf formed by jutafs. Stahl ; but was firft accurately defcribed by BerthoUet, Fourcroy, and Vauquelin. It may be formed by pafTmg fulphurous acid into a faturated folution of carbonat of potafs till all effervef- cence ceafes. The folution becomes hot, and cryflal- I Fourcroy, lizes by cooling ||. nd Vauque- jjg cryftals are white and tranfparent ; their figure Vj loun '^^' °^ rhomboidal plates. Its cryftallization often pre- . 317. fents fmall needles diverging from a common centre *I. Ibid. Its tafte is penetrating and fulphurous. At the common temperature of the atmofphere, it is foluble in its own weight of water, but much more foluble in boil- ing wnter. 3^5 When expofed to the air, it efflorefces, becomes Siilphiies. opaque and hard, and is gradually convened \nio fulphat ^— — v— -^ of potafs by abforbing oxygen. When expofed to a fudden heat. It decrepitates, lofcs Its water : at a red heat fome fulphurous vapours are emitted ; at lull a portion of fidphur feparates, and the refiduum is fulphat of potafs, with a flieht excefs of al- kali. Nitric and oxy muriatic acids convert it into fulphat of potafs by imparting oxygen. It dti.ompofes the ojtides of gold, filver, mercury, the red oxide of lead, the black oxide of manganefe, and the brown oxide of iron. When the green oxide of iron and the white oxide of iron are boiled with it in water, and an acid added, a precipitate takes place of thefe bodies united to fome fulphur, and the filt is convert- ed into a fulphat : at the fame time fulphurated hydro- gen gas is emitted. By compound affinity it is decompofed by All falls with bafe of foda, except the borat and car- bonat ; All metallic falts except carbonats ; All neutral falts whofe acid has a ftronger affun'ty for potafs than fulphurous acid has*. » 7h\i. 2. Kulphite of foda. — This fait was firft accurately '>t>° defcribed by Fourcroy and Vauquelin. Sulphite of It is white and pcrfedly tranfparent. Its cryftals '^°''*' are four-fided prifms, with two very broad fides and two very narrow ones, terminated by dehedntl pyramids. Its tafte is cool and fulphurous. It is^ foluble in four times its weight of cold water, but it is more foluble in hot water. It is compofed of iS,8 parts of foda, 31,2 of acid, and 50 of water. By expofure to air, it e/Horefces, and is flowly con- verted into a fulphat. When expofed to heat, it undergoes the watery fu- fion, and afterwards exhibits precifely the fame pheno- mena as the fulphlte of potafs. Metallic oxides and falts affeft it precifely as they do fulphlte of potafs. It is decompofed by compound affinity by carbonat of potafs, and the other falts which decoinpofe fulphlte of potafs f . j^.j 3. Sulphite of ammonia. — This fait was firft defcri- aVr bed by Fourcroy and Vauquelin J. sulphite of It cryft.dllzes in fix-fided prifms terminated by fix- »n'">onia- fided pyramids. t Fo^rc.oy T. 1 n ■ 1 , . ... and ^ui/jirf. Its tafte IS cool and penetrating like that of the/;„ NUM. other ammoniacal falts, but it leaves a fulphurous im-/»"'-' J'^rn, prcffion in the mouth. i- 3'7- It is foluble in Its own weight of cold water. Its folubllity is increafed by heat. It is compofed of 29,07 parts of ammonia, 60,06 of acid, and 10,87 of water. When expofed to the air, it attrafts moifture, and is foon converted into a fulphat. Heat volatilizes it without decompofition. Its habitudes with metallic oxides and falts are nearly the fame with thofe of the above defcribed fulphltes, ? S'llphite of lime. f /inn (/c Cij'ff:- il'iJ- tit. 5 Ibid. 664 Snlphi'e pf magneGa. II Fourcrey and Vau(iue- tin. 665 Sulphite of alumina. ^ Fourcroy and yauqut- lin. 666 Sul|'hi(e rf iron * j4nn. de dim. ii. j 8. 667 Kitre. It is compofeJ of 59 parts of barytcs, 39 parts of acid, and ?. of water. It dues nut t;ilily Chanel' into a fiilpliat by expofure to air ; but htat produc^:^^ iliis cffcft *- 5. Sulphite of lime. — This fait was firll defcribed by IJertholltt f. Jts cryllals are fix-fided prifms, terminated each by a very long jiyramid;]:. It has fcarcely any tafte ; however, when kept long in the mouth, it communicates to the tongue a tafte which is maniftftly iulphurous. It is very fparingly foluble in water, except with ex- cefs of acid. It is compofed of 47 parts of lime, 48 of fulphurous acid, and 5 of water. By contadt of air it is converted into a fulphat, but verv flowly. Heat converts it into a fulphat by depriving it of a portion of fulphur. It is decompofed by compound affinity by Carbonates of alkalies, Fluats of alkah'es, Pliofphats of alkalies, Moft metallic falts §. _ 6. Sulphite of magnefia. — This fait was firft defcri- bed by Fourcroy and Vauquelin. Its crvllals are white and tranfparent, and in the form of deprefled tetrahedrons. Its tatte is mild and earthy at firft, and afterwards fulphurous. It is fparingly foluble in water, except when there is an excefs of acid. It is compofed of 16 parts of magnefia, 39 of acid, and 45 of water. It becomes opaque when expofed to the air ; is very flowly converted into a fulphat. By expofure to heat, it foftens, fwells up, and be- comes duftile like gum ; a ftrong heat decompofes it altogether. It is decompofed by Alkaline falts. Earthy falts, except thofe of alumina ||. 7. Sulphite of alumina — Firft formed by Berthollet. It does not cryftallize, but is converted into a foft duftile mafs. It is not foluble in water, but becomes abundantly fo when there is an excefs of acid. It is compofed of 44 parts of alumina, 32 of acid, and 24 of water. Heat decompofes it ^. ■ 8. Sulphite of iron. - It was firft formed by Berthol- let. Its cryftals are white, and have but very little of the ftyptic tafte of iron falts *. Berthollet alfo formed the fulphites of zinc and tin, but he has not defcribed them. Sect. III. 0/ Nitrats. Those falts, in the compofition of which the nitric acid forms one ingredient, are called nitrats. I . Nitrat of potafs, nitre, or faltpetre. — As this fait is produced naturally in confiderable quantities, parti- cularly in Egypt, it is highly probable that the ancients were acquainted with it ; but fcarcely any thing cer- tain can be collefted from their writings. If Pliny mentions it at all, he confounds it with foda, which was known by the names of nitron and nitrum. It is cer- tain, however, that it has been known in the eaft from time immemorial. Roger Bacon mcnliuns this fait in Niti-.m. the I ^th century under the name of iiitrf. •' ' It-cryllalli/.cs in flender oblong hexagonal prifms, of- ten ftriated, terminated by hexagonal pyramids oblique- ly truncated. Its fpecific gravity is 1,920. Its t.>oft convenient method of procuring ])ure barytes yet known. It was firft propofed by Mr Vauciuelln. By compound affinity it is decompofed by Alkaline carbonats, Oxalat of ammonia *. * Sergmon, 5. Nitrat of lime. This fait forms by cryftalllzation ^^^ *^' fix-fided prifms, terminated by dehedral pyramids, bat|,,J|j'' more commonly fmall regular oflahedral needles. It has a ftiarp bitterifli tafte. It is foluble in two parts of cold water, and in its own weight of boiling water. Boiliiig alcohol diftolves its own weight of it f . t ?"■.?»"'•." According to Bergman, it is compofed of 43 parts of acid, 32 of lime, and 25 of water. Kirwan has found, that 100 parts of lime require for faturation 1S0 parts of acid f. t Min,r.\l Nitrat of lime deliquefces when expofed to the air. ir- Heat decompofes it like all other nitrats. By compound affinity it is decompofed by Sulphat of barytes, Acetite of potafs, Carbonat of barytes, potafs, foda. potafs, — — foda, ■ ammonia, alimiina, Muriat of barytes, potafs, ammonia, alumina, magnefia. Acetite of barytes, Tungftat of ammortia (). ^ SchrtU. 6. Nitrat of ftrontites. This fait, firft formed by Dr' 67? Hope, cryftallizcs readily, but the cryftals are very irre- '^""'. '^^ gular in their (liape : fometimes they are hexagonal '^"""■'^'° truncated pyramids; fometimes oftahedrons, confiding of two four-fided pyramids united at their bafes. It IS foluble in its own weight of water, at the tem- perature of 60", and in little more than half its weight of boiling water. It has a ftrong pungent tafte. In a dry air it elHorefces, but in a moift air it deli- quefces. It deflagrates on iiot coals. Subjeded to heat in a crucible, it decrepitates gently, and then inelts. In a red heat it boils, and the acid is diffipated. If a com- bullible fubftatiee be at this time brought Into contact with it, a deflagration with a very vivid red flame is produced II . || }i,p,^ 7. Nitrat of magnefia. The <;omppCtion of this i-d\tTran/. ILJin was firll afcertained by Dr Black. '*• '*■ Its cryftals are quadrangular prifms. It has a very xjj„j*pf bitter tafte. It is very foluble in water. Alcohol dif-niifri.ffia. folves ^th of its own weight of it <[[. 1[ V.^gmnn, One hundred parts of magnefia require 255 of nitric "■''''■ acid for faturation *. ^ Kirtv-in It deliquefces in the air, according to Bergman; bi\t Dijonval affirms, that he has procured it in cryftals which rather eiflorefce. It 368 CHEMISTRY. Part nr. Nitrat«. It is decompofeJ by heat. By campouiid affinity it is Jecompofed by 675 Nitrat of am.n. rii Sulpliat of barytes, potafs, foda, —— ammonia, alumina, Muriat of barytes, potafs, foda. Muriat of lime, Acetite of barytes, potafs, — — foda, - — lime, Carbonat of barytes, potafs, ^-^ lime. Its folution is exceedingly cauftic. Wlien placed on Nitrau. burning coals it melts and detonates as it dries. It k * can fcircely be dried without being in fome raeafure de- compofed. Chim. iv. 676 Kitiat of alumina. ft77 Nitra' of jargouia. 8. Nitrat of rmmonia and magnefia. This triple fait was difcovercd by Mr Fourcroy. Into a faturated lo- neCa""^" '"'^'°" '^^ nitrat of magnefia, containing 73 grains of magnefia, he poured ammonia as long as any precipi- tate could be obtained. Twenty-one grains of magne- fia were precipitated, i;2 grains remained combined with the acid and the ammonia. He found that 52 grains of magnefia produced, when faturated with nitric acid, 288 grains of nitrat ; and that the quantity of nitric acid neceffiry to faturate 21 grains of magnefia, when faturated with ammonia, produced 84 grains of nitrat of ammonia. He concludes, therefore, though the da- ta are not quite fatisfaClory, that the triple fait is com- pofed of 2S8 grains of nitrat of magnefia, and 84 of ni- trat of ammonia *. 9. Nitrat of alumina. This feems to have been firll attended to by Beaume. Its crylldls are pyramidal. It has a very aftringent tafte. It is foluble in water, and deliquefces in the air. 10. Nitrat of jargonia. This fait may be eafily formed by pouring nitric acid on newly precipitated jargonia. It alwa>s contains an excefs of acid. By evapora- tion a yellowifli tranfparent matter is obtained, exceed- ingly tenacious and vifcid, and which dries with diffi- culty. It h:is an aftringent talle, and leaves on the tongue a vifcid matter, owing to its being decompofed by the faliva. It is only very fparinj^ly foluble in wa- ter ; the greatell part remains under the form of gela- tinous and tranfparent flakes. Like all the other falts into which jargonia enters, it is decompofed by heat. It is decompofed alfo by fulphuric acid, which occafions a white precipitate, foluble in excefs of acid; by carbonat of ammonia, which produces a precipitate foluble by adding more carbonat ; and by an infufion of nut-galls in alcohol, which produces a white precipitate, foluble in an e::cefs of the infufion ; unlefs the jargonia con- tains iron ; in which cafe the precipitate is a greyifh blue, and part of it remains infoluble, giving the liquor a blue colour. This liquor, mixed with carbonat of am- monia, produces a matter purple by tranfmitted light, but violet by refleded light. Gallic acid nifo precipi- tates nitrat of jargonia qi a greyilh blue, but the co- lour is not fo fine. Moll of the other vegetable acids decompofe this fait, and form combinations infoluble in water f. till, Ann. dz J J _ Nitrat of iron. The green oxide of iron decom- Cbim.xxn. ^^f^^^ j^^ ^j^gg j,ot combine with nitric acid. The ^^678 brown oxide forms with it a red or brown folution, Nitrat of which by evaporation may be reduced to a jelly, but will not cryllallize. 12. Nitrat of zinc. The oxide of zinc combines with nitric acid, and forms with it a fait which cryftal- lizes in compreffed and ftriated tetrahedral prifms, termi- nated by four-fided pyramids. f Vauquf iron. 679 Nitrat of zinc. It deliquefces in the air *. * Foi '•ircroy. I 13. Nitrat of manganefe. This fait, compofed of ^So oxide of manganefe and nitric acid, was firft examined "' °^ by Scheele. Its cryftals are fmall and Ihining, of a ' *" very bitter tafte, and foluble in water f . f ScbcrU on 14. Nitrat of cobalt. It is of a pale red colour, and-^'"l?'"'c/'> cryftallizes in needles. It deliquefces when expofed to,,.''''' , 1 ■ TT 1 r ■ TTM • 1 1 • r Nitrat of the air. rleat decompoles it. When nickel is prelentjcob^it this fait affumes a green colour. gj 15. Nitrat of nickel. Its cryftals are of a green CO- of nickel, lour, and in tiie form of rhomboida! cubes. They are dehquefcent, and are gradually decompofed when expo- fed to the air, the acid leaving theiTi|. t Bcnman /6. Nitrat of lead. Nitric acid combines with theii. a6S. white oxide of lead. The cryftals of this fait are of a "'^J white colour ; their form an irregular oftagon, or ra- ' ther truncated hexahedral pvramid. When expofed to heat it decrepitates, and melts with a yellowiih flame. By compound affinity it is decompofed by Muriat of potafs, foda, ammonia, Carbonat of foda §. { Btrgmm, 17. Nitrat of tin. Tin is converted into an acid hy j.^. ■* nitric acid : it is not probable, therefore, that any per- ' manent nitrat of tin can be formed. gg, 18. Nitrat of copper. This fait appears to have been Of coppe.-, firft obtained by Macquer. Its form, when properly cryftallized, is an oblong pa- rallelogrcioi. It is of a fine blue colour. It is exceed- ingly cauilic. It melts at 77^^11. | It is deliquefccnt in a moift air, but in a dry place is covered with a green efflorefcence. It is very loluble in water. Heat decompoies it. 19. Nitrat of bifmuth. This fait cryftallizes in va- Of bilmuth, rious forms. Fourcroy obtained it in flattened rhom- boids. It. efflorefces in the air. Water deconipofes it. It detonates in the fire. ,„ 20. Nitrat of antimony. Little is known concern- of i,,tin,o. ing this fait, except that it is very deliquefcent, and isny, decompofed by heat. ^gg 21. Nitrat of arfenic. With white oxide of arfenic Of arfenic, nitric acid forms a fait which cryftallizes. It is very deliquefcent. It does not detonate. , 22. Nitrat of mercury. This fait may be formed by Qf ^^^^^^ diffolving mercury in nitric acid. It cryftallizes in the^j', cold in regular flat 14-fided figures ; but their form dif- fers according to the manner in which the cryftalliza- tion has been performed. It is foluble in water. This fait is exceedingly cauftic. It detonates on coals. When heated in a crucible it melts, and is de- compofed. The oxide attracts oxygen from the acid, which flies off in the form of nitrous gas, and red oxide of mercury remains behind. It is (lowly decompofed alfo in the air. It is decom- pofed by compound affinity by Sulphat of copper, and a great many other fulphats, Phofphat of foda, Borax. 6jo 23. Nitrat of ammonia and mercury. This triple Of ammo- fait may be formed by pouring ammonia into a folution ma ani 16. Muriat of nickel— This fait is deliquefcent, and .'l"^^''' lofes its acid when expofed to the air ^. ,^ iCif''"' 17. Muriat of lead. — Muriatic acid combines with depofited : if the evaporation be ftopped before the mafs oxide of lead eafily enough : but this fait is more readi- be reduced to drynefs, it forms a kind of jelly when ly procured by pouring muriatic acid into a folution of cold. It is alfo decompofed by the phofphoiic, citric, nitrat of lead ; the muriat immediately precipitates in tartarous, oxalic, and faccholaftic acids, which form the form of a white powder. It is foluble in ^o times with jargonia infoluble compounds that precipitate in its weight of boiling water ; and the folution yields by white flakes. evaporation fmall, flender, brilliant needles in bundles. The gallic acid poured into muriat of jargonia pro- It is fomewhat deliquefcent. When expofed to heat, duces a white precipitate ; but a green, bordering on it melts into a brown mafs, formerly called corneous grey, if the jargonia contain iron ; and this laft pre- lead. 712 llead. cipitate becomes, when dry, of a bright black colour, and refembles China ink. The liquid preferves a green- ilh colour ; new portions of gallic acid produce no far- ther precipitation ; but carbonat of ammonia feparates in great abundance a flaky matter of a purplifh colour, not unlike that of the leys of wine. From thefe expe- riments it follows, that gallic acid has a greater affinity for jargonia than muriatic acid has ; and that the gal- iats ot jargonia and iron are ioluble in muriatic acid. It is decompofed by compound affinity by Sulphatoff.lverll, \\ B^rgma,, Carbonat ot loda. 713 18. Muriat of tin This fait may be formed by dif- Tin, folving tin in hot muriatic acid. By evaporation it aftords needle-fhaped crylltds, which are deliquefcent. This fall has a flrong affinity for oxygen. It de- compofes oxy-muriatic, nitric, fulphurous, arfenic, mo- lybdic, and tungftic acids, the red oxide of mercury, Carbonat of potafs decompofes muriat of jargonia, black oxide of manganefe, oxide of antimony, zinc, iil- 3 A 2 ver, (v) Only at a high temperature. See Muriat of jimmonia. 372 Muriits. * PclUtitr, jinn, de Chim. xii. .714 Muriat of copper, ■f" Bergman. Ti Muriat of bifmuth, 716 Antimony, 7>7 Arfenic, t Bergman^ il 293. 718 Mercury, § Bergman. 719 Muilat of ammonia and mer- tur)-, }l Fourcny, Ann de Chim. xiv. 47- 710 Muriat of fiker. 7»t Muriat of titanium. C H E M I ver, and gold; and by that means is converted Into oxy- muriat of tin. It even abforbs oxygen when expofed to the air *. Thefe compofitions are doubtlels produ- ced by difpofwg affinity. 19. Muriat of copper. — This fait may be formed by diffolving copper or its oxide in muriatic acid. Its cryftals are prifmatic. It is of a beautiful grafs green colour. It has a very aftringent and cauftic tafte. It deliquefces when expofed to the air. A moderate heat is fufficient to melt it; and when cooled it congeals into a mafs. It requires a ftroiig heat to volatilize it. It is decompofed by nitrat of filver-|-. 20. Muriat of bifmuth. — This fait cryflallizes with difficulty. By fublimation it forms a folt fufible fub- ftance, formerly called butler of lifmuth. 21. Muriat of antimony. — This fait is found native. It cryftallizes in prifms. When heated it evaporates. 22. Muriat of arfenic. — This fait cryftallizes ; it is very volatile, and not very foluble, in water J. 23. Muriat of mercury. — This fait may be prepared by pouring diluted muriatic acid into a diluted folu- tion of nitrat of mercury : the muriat of mercury is immediately precipitated in the form of a white pow- der. Common fait may be ufed inftead of muriatic acid. This fait was formerly called •white mercurial precipitate and calomel. It cryftallizes ; but the form of the cryftals, which are very fmall, has not been determined. It has little tafte. It is almoft infoluble in water. It is ufed as a medicine. It is decompofed by fulphat of ammonia §. 24. Muriat of ammonia and mercury. — This triple fait was firft difcovered by Fourcroy. It may be form- ed by pouring ammonia into a folutlon of corrofive mu- riat of mercury. It has the appearance of a white powder. Its tafte is at firft earthy, afterwards metallic. It is nearly Infoluble In water. According to Fourcroy's analyfis, It Is compofed of 81 parts of oxide of mercury, 16 of muriatic acid, and 3 of ammonia. Heat decompofes It; producing ammonia, azotic gas, and muriat of mercury. Sulphuric, nitric, and muriatic acids decompofe it ||. 25. Muriat of filver. — This fait may be formed by dilTolvIng oxide of filver In muriatic acid, or, which is better, by pouring muriatic acid into nitrat of filver; muriat of filver Immediately precipitates. It is very little foluble in water ; according to Monnet, one part of it requires 3072 parts of water. When expofed to a fmall heat, It melts into a grey fe- mitranfparent mafs, not unlike horn ; hence It was for- merly called luna cornea. A long continued heat de- compofes It. This fait Is very cauftic : it is employed as an efcharotic under the name of lunar caujlic. 26. .Muriat of titanium has been formed by Mr Kla- proth. 1 Sect. VI. 0/ Oxy-muriats. Those falls, into which the oxy-muriatic acid enters as an Ingredient, are called oxy-muriats. As we confi- der the nitro-muriatic acid to be precifely the fame with the oxy-muriatic, its combinations of courfe muft receive the fame name. S T R Y. Part III. 1. Oxy-muriat 6f potafs. — This fingular fait was dlf- Ox\.mu. covered by Mr BcrthoUet in 1786. It may be formed ■''^'s- by faturatiiig a folutlon of potafs with oxy-muriatic ^ acid gas. By evaporating this folutlon in the dark.OiT.mn- common muriat of potafs is firft obtained : When It Isriatof pot. feparated, and the liquor allowed to cool, oxy-muriat'''^*" of potals cryftallizes. Its cryftals are rhomboids, of a filvery brilliancy. It has an Infipid cooling tafte, refembling that of nitre. It Is foluble in 1 7 parts of water at the temperature of 60, and in 2i parts of boiling water *. It does 'not* Mtylt^ deliquefce in the air ; but light converts it into com- !*« by diifolving tin in muriatic acid, and then faturating it'*^' with oxy-muriatic acid gas. It is ufed in dyeing. .j- 9. Oxy-muriat of iron. This fait is deliquefcent ; Oxy-mu- colourlcfs ; of a pure bitter tafte, without any of the riat i^f iron, fweet aftringency of the common falts of iron J. j r.amte. Few of the other oxy-muriats have been hitherto ex- MambcJItr amined with attention : Many of the metals, indeed,^'"- ^• have been diffolved in aqua-rcgia ; but in moll of thefe''" '" folutions the fait produced is a common muriat. The nitric acid fupplies oxygen, and the muriatic acid dif- folves the oxide. Sect. VII. Of Phofphats. Those falts, into which phofphoric acid enters as an ingredient, are called phofphats. This clafs of falts was firft difcovertd by Margraf. «jg. 1. Phofphat of potafs. This fait cryftalllzes in fliort Phi.fphat tetrahedral prifms, terminated by quadrangular pyra- '^f P"'*'^) mids. It is very foluble in cold water, and ftill more fo in hot water. It decrepitates on ignited coals like common fait. W.hen a very ftrong heat is applied, it melts into an opaque vitreous mafs, ftill foluble in water. The following falts decompofe it by compound affi^ nity : Sulphat of lime, Muriat of mercury, Nitrat of mercury, Acetlte of lead. 2. Phofphat of foda. — Dr Pearfon, who firft formed phofphat this fait, gives the following procefs for preparing it ; of foda, Diflblve ill a long-necked matrafs 1400 grains of cry. ftallized carbonat of foda in 2100 grains of water at the temperature of 150". Add gradually 500 grains of phofphoric acid of the fpccific gravity 1,85, Boil the liquor for fome minutes ; and while it Is boiling hot,, filtrate it, and pour it into a Ihallow veflcl. Let it re- main In a cool place, and cryftals will continue to form for feveral days. From the above quantities of mate- rials he has obtained from 1450 to 1550 grains of cryftals. Its cryftals are rhomboidal prifms, of which the acute angles are 60 , and the obtule angles \20'', terminated by a three-iided pyramid. Its tafte is almoft the fame with that of common fait. It is foluble in water. When expofed to the air it efflorefces. This lalt has been introduced into medicine as a pur- gative, and on account of its pleafant tafte has of late been much ufed. It Is ufually taken in broth, which it is employed to feafon inftead of common fait. Hellot remarked a particular fait in urine, different from thofe that had ufually been obferved, in 1737. Haupt defcribed it in 1740 under the name oi fal mi- rabile (a) If we liften to Junker, the ancients applied the name mcrcurium to this fait ; mercury they called argeti' turn vivum. 374- C H E M I I'lu.f, hits. y,,/,;/^^^,.;,,/;,„^ ox wontfcrfiil perlctltcl fa!l. It was call- * fd perhiteil troni the grey, opaque, pearl-like colour uhijh it afTumi'd when melted bv tlie blow-pipe. Mar- p-iii deferibcd it in 1741;, and found it would not yield piiofphorus when treated with charcoal, as the other lalts of urine did. Roiielle the Younger analyfed it in 1776, and concluded from his experiments that it was a compound of phofphoric acid and foda ; but Mr Proud, being unable to obtain phofphorus from it, con- cluded, that it did not contain phofphoric acid, but •another acid analogous to the boracic. To this fub- iUnce, which Mr Prouft aftually obtained, Bergman gave the name oi perlated add, and Morveau afterwards called it ouretic acid. But Mr Klaproth foon after- wards analyfed it, and proved that it confifted of foda fupcrlaturaled with phofphoric ae.id. Scheele foon af- ter made the fame difcovery. This acid of Mr Prouft, then, is merely phofphat of foda combined with phof- ,^3 phone acid, or acidulous phofphat of foda, 3. Phofphat of ammonia. — This (alt forms oblong- pointed cryftals, pr, as Mr Lavoifier aflirms, cryftaU re- fembling ihofe of alum. It is foluble in water. Heat evaporates it fo eafily, that it is difficult to obtain it in cryftals except by adrl- ing an exeefs of alkali. Microcofmic fait, or fait of urine, is merely a mixture of thefe two laft defcribed falts. 4. Phofphat of barytcs. — This fait is infoluble in water *. Of lime, 5- Phofphat of lime. — This fait is taftelefs, and al- moft perfeftly infoluble in water. It forms the balls of bones, and is therefore often called earth of bones. Wenzel obferved it cryftallize when held in folution by phofphoric acid. It is decompofed by fulphat of ammonia f . Carbonat of potafsj, • foda ^ . 6. Phofphat of ftrontites. — This fait was firft formed by Dr Hope. It is a white powder foluble in 1920 Phofphat ol auimo- 731 Of "1 arytes \ntlhfiamp Chim, vi. 37- % Bergman. § Id. 733 Of (Iron . ti'es, Dr Ho/,. parts of boiling water | 7. Phofphat of magnefia. — This fait does not cry- ftallize except with exeefs of acid, and then the cry- Tn^y: £ftalHzes in fmall tior^ts. grains hardly foluble in water *. ' v- ■ < 14. Phofphat of uranium. — Firft formed by KInp-Qf'''° . roth. It does not cryftallize, but afl"umes the appear- * a,.':^wa';,' ance of yellowilh white flakes, diffieultty foluble inii. ago. ' water. ;.)i 15. Phofphat of antimony and lime. — Dr Pearfon *^^ *"^*' has difcovered, that ihe well known medicine called'""!'' ^ jfames'i Powder is a triple fait, compofed of phofphoric James"? acid, oxide of antimony, and lime. It is very inlolublcP^'WJcf. in water. The remaining phofphats are fcarcely known. Sect. VIII. Cf Borais. The compounds into which the boracic acid enters are called borats. 1 . Borat of potafs. — This fait, formed by combining Boiat ot boracic acid and potafs, is very little known. Baron put»fs, firft formed it. Borat of potafs cryftallizes, is foluble in water, and may be melted into a vitreous mafs, fo- luble in water. .^, 2. Borat of foda or borax. — This fait is brought Of foda, from the Eaft Indies in an impure ftate under the name of tinkal. When purified in Europe, it takes the name of borax. Its cryftals are hexangular prifms, of which two fides are much broader than the remainder, terminated by triangular pyramids. It is of a white colour. Its fpe- cific gravity is 1,740. Its tafte is ftyptic and alkaline. It is foluble in 18 times its weight of water of the temperature of 60°, and 6 times its weight of boiling water. It is compofed, according to Bergman, of 17 parts of foda, 39 of acid, and 44 of water. When expofed to the air, it efflorefces flowly and flightly. When heated, it fwells, lofes about four-tenths of its weight, becomes ropy, and then aflumes the form of a light, porous, and very friable mafs, known by the name ot calcined borax ; it then melts into a tranfparent glafs, ftill foluble in water. By compound affinity it is decompofed by . Nitrat of mercury f. | Bergman. When two pieces of borax are ftruek together in the dark, a flafh of light is emitted J. * Aeevm Borax has the property of facilitating the fufion oiNkhotfon'i a great number of bodies. This property renders it 7'""'''«'> "• ufeful in glafs-making, In aflaying ores, and in folder-* ing metals. Borax turns fyrup of violets green; it appears there- fore to be fuperfaturated with alkali. The real borat of foda, or the fait in which boracic acid and foda faturate each other, has not yet been exa- mined with attention. According to Dr Withering, foda requires twice its weight of boracic acid to fatu- rate it. 3. Borat of ammonia.- — This fait has been examined of Imm* I only by Mr Fourcroy. Its cryftals are polyhedral pyramids. It has a poignant urinous tafte, and turns fyrup of violets green. It diffolves readily enough in water. , r . It isgreenifh, and does not When expofed to the air, it gradually lofes its cryftal-^if^J; Jine ferm and becomes brown §. Pattii. 4. Borat ch. 4. Part in. Borats. 746 Of lime, 747 Of (Iroll- tites. * Ho/i-, Trarif. Edin. jv. 17. 4. Borat of baiytes. — Unknown. 5. Borat of lime. — It is difficultly foluble in water, and did not cryftallize with Beaume. 6. Borat of llrontites. — This fiilt was firft formed by Dr Hope. — It is a white powder, loKible in about 130 parts of boilinj;; water. The folution turns the fyrup of violets green •. 7. Borat of magncfia. — It aflTumes the appearance of CHEMISTRY. It ia taftelefs and nearly infoluble in wafer. fpecific gravity Its 748 fmall irregular cryftals. It is toluble in acetous and ior- Of magne mic acids. Alcohol decompofes it. It melts eafily in ^^' the fire without Ijting decompofed f. ■f ergm It, g Borat of alumina. — It does not cryftallize, and is fcarcely foluble in water. o. Borat of iron. — Its cryftals are of a yellow culour, but the fait has never been examined with attention. 10. Bojat of zinc.-*This fait does not appear to be capable of cryllallizing. By heat, it melts into a light green infoluble flag J. J I. Borat of cobalt. — When o.xide of cobalt is melt- ed with boracic acid, a bluifh grey flag is produced. This, by lixiviation and evaporation, yields cryftals of a reddilh white colour and ramified form §. 12. Borat of nickel. — A faline fubltance difficultly jj. 33f. 749 Of alumi- na, 7^0 Of iron, 751 Of 21DC, 751 Cnbalt, 753 Nickel II Btrg"'"'- foluble 7i4 Lead, 755 Tin, 756 3. Borat of lead. — When boracic acid and red oxide of lead are melted together, the produCl is a fine grecn- ifli yellow, tranfparent, hard, infoluble glafs ^. 14. Borat of tin. — When equal parts of boracic acid and tin filings are melted together, the produft diffol- ved in water yields by evaporation tranfparent white polygonous cryftals. 15. Borat of copper. — When borax is poured into a folution of fulphat of copper, borat of copper is preci- pitated in the form of a pale light green jelly, which when dikd is with great difficulty foluble in water. It eafily m Bergman, melts into a dark red vitreous lubftance*. According to Palm, by long trituration of filings of copper and boracic acid in water, and then digtiling the mixture, it diffolves, and cryftals may be obtained from it. 16. Borat of bifmuth.— A white powder, which melts into a white tranfparent permanent glafs f. 17. Borat of arfenic. — White oxide of , artenic and boracic acid form a. fait- foluble in water and cryftjl- lizable J. Sect. IX. Bifmuin, ^ li erfz.eL 758 Arfenic, J Rcuji. Of Fluau. Those falts into which fluoric acid enters are called Jluats. Thty were firft formed by Schecle. 1. Fluat of potafs. It forms a gelatinous mafs al- moft without tafte. It diffolves readily in water. When expofcd to the ISchceUaa fire it melts without any ebulition § fluor. 759^ Fluat of fotaf?, 760 Snda, Ib\ Ammonia, ^ lyitgtli. 761 BarvtfB: 2. Fluat of foda. This fait refembles exadfly the fluat of potafs j|. 3. Fluat of ammonia. It cryftallizes in fmall prifms. It is deliquefcent, and. is partly decompofed by heat<([. It is decompofed by Nitrat of mercury, filver, . lead. 4. Fluat of barytes. A powder which requires a - Birg'/ian. large quantity of water to diflblve it *. 76.S J. Fluat of lime. This fait abounds in nature. It *^'"^' is known by the name of fluor fpar. It cryftallizes moft commonly in the form of cubes. 764 It is not altered by the air. about 3,1. When expofed to a fudden heat it decrepitates. A very violent heat melts it into a white opaque mnfs. When reduced to powder and heated it becomes phof- phorefcent ; but it lofes this quality altogether if it be heated red hot. 6. Fluat of ftrontites. This fait was formed by Dr Hope : but its properties have not been examined. 7. Fluat of magnefia. — It is not foluble in water ex- l^agneCaj cept there be an exctfs of acid. In that cafe, by fpon- taiieous evaporation, it forms hexagonal prifms, termi- nated by a low pyramid compofed of three rhomboidal fides. Thefe cryftals are hardly foluble in water. Alcohol diffolves a fmall portion of them. Heat does not de- compofe them *. » n b. rluat of alumma. A faline mafs; which is fweet- 'i- 384. i(h, clammy, and gelatinous. 705 9. Fluat of filica. Little is known concerning this '^'"'^g"^' Angular combination, except that it can cxift in a ga- SiUta, feous form, and that it dcpofites filica in cryftals after a certain time. I o. Fluat tf filica and potafs or foda. This triple fait may be formed by pouring fixed alkali into a folu- tion of fiuat of filica. It contains an excefs of acid. On evaporation it yields a kind of jelly, which when ■ dry feparates into gritty particles like fand. It is fo- luble in 96 parts of hot water. In the fire it readily melts into a white mafs. If the heat be continued the acid feparates, and there remains a tranfparent glafs, which is foluble in water, and forms a liquor Jt!icum\. ^ 5^^,,);. 11. Fluat of iron. It is incryftallizable ; but when rr,/r,7«r. evaporated leaves a haid mafs, ""A i. sc?-. 12. Fluat of zinc. It refembles that of iron. t"frTraniI. 13. Fluat of manganefe. It may be formed by pour-MmlUc ing fiuat of ammonia into a folution of oxide of zinc influats. any of the three mineral acids. It cryftallizes. 14. Fluat of cobalt. A yellow gelatinous mafs. 15. Fluat of nickel. It affords green cryftals. 16. Fluat of lead. A fweet tafted powder. 17. Fluat of tin. A naufeous tafted jelly. 18. Fluat of cupper.. Blue cryftals ; fome of them'" oblong, others cubic. 19. Fluat of arfenic. Small cryftals. 70. Fluat of mercury. A powder. Before the blow. pipe it melts into a yellow glafs, moft of which evapo- rates by a continued heat |. , .W«/.ott ■ Sect. X;. Of Carbonats. ^'"°^- The compounds into which the carbonic acid enters are called carbonats. They were firft analyfcd by Dr Black. I. Carbonat of potafs. This fait is formed by fatu-o '1 ,, - rating potals with carbonic acid, which is beft done byof potafc^ expoling a folution of potafs fur a coiifideiable time to carbonic acid gas. It cryftallizes, according to Bergman, in quadrangular prifms ; the apexes of which are compofed of two in- verted triangles, converging like tiie roof of a houfe ||.i| According to Pelietier they are tetrahedral rhomljoidal prifms, with dihedral funuiiits. The complete cryftal has eight faces, two hexagons, two redanglcs, and four rhombs ^. BLrgman, It * Ann. dt ■ CUm, XT, 13. 37« G H E M I t PlUltitr. Carhonati. It hii an alkalin«, hut not « caufti'c taftc, ^~~^ It is foluble at the common temperature in about J "^'"' io\xr times its weight in water*. Boiling water dif- folves |ths of its weight f . Alcohol, even when hot, does not dilTolve above xt'bo^ parts of it. AccordiiiiJ' to Bergman, it is compofed of 48 parts of potafs, 20 of acid, and 32 of water. According to Pel- ieticr, of 43 parts of acid, 40 of potafs, and 17 of water. Bergman under-rated the quantity of acid from not ob- ferving that the fait lofes part of its acid when heated. Even fohition in hot water produces a feparation of feme acid J. It is not altered by expofure to the air. Heat deprives it of its water and part of its acid, but does not decompofe it completely. The following falts deconjpofe it by compound affinity ; %U ^ Bergman, 11 /i Sulphat of lime, — barytcs, — — foda, — — ammonia, magnelia, . alumina, Muriat of barytes, lime, ~— — ammonia, •^— magnefia, alumina, foda §, Nitrat of barytes, foda, — ammonia, magnefia, — • alumina, Acetite of barytes, I lime, . ammonia, I magnefia, alumina, Oxy-muriat of mercury, Phofphat of hme \\. 769 Carl>onat of foda. Nitrat of lime, When potafs is faturated with carbonic acid it al- ways lets fall a quantity of filica. Mr Pelletier has pro- pofed this faturation as the bell method of purifying potafs from that earth. 2 Carbonat of foda. This fait may be formed in the fame manner with carbonat of potafs. Its cryftals are fivefided prifms, vs'ith one of the an- gles frequently truncated, furmounted by dihedral pyra- mids with rhomboidal faces. Its tafle is precifely the fame with that of carbonat of potafs. It is foluble in double its weight of cold water. It is compofed, according to Bergman, of 1 6 parts of acid, 20 of alkali, and 64 of water. It efflorefces when expofed to the air. Heat is inca- 5 Bergman, p^^lg of decoiiipofiiig it completely ^. *■ ' The following falts decompofe it by compound affi- nity : Sulphat of ammonia, barytes, . lime, magnefia;}:, alumina. \ Bergman* 770 Carbocat of ammo- nia, % Bergman, 111, Muriat of barytes, ammonia, . lime, •^— magnefia, alumina, Acetite of barytes, ammonia, lime, magnefia, alumina, Nitrat of ammonia, magnefia, alumina, lead*, Phofphat of lime f . This lalt forms oftahe- S T R Y. Part lit. cold water. Hot waM!" diHfj've? iti own weight of it. C^rbpn^ts, According to Bergman it is compofed of 43 parts of ^— — y-— ' alkali, 45 of acid, and i 2 of water. When expofed to the air It becomes fomewhat moift. The fmallell heat is fuiHcient to evaporate it. The following falts decompofe it by compound affi- nity : Acetite of barytes, lime, magnefia, — — alumma. Sulphat of alumina, Nitrat of lime, Muriat of lime, magnefia, — — alumina, /\. Carbonat of barytes. native. This fait has been fouad Carbonat of barytes. Its cryftals have been obferved to affume four diffe- rent forms; double lix-fided art*] double four-fided py- ramids, fix-fided columns terminated by a pyramid with the lame number of faces, and fniall radiated cryftals 4 an inch in length, and very thin, appearing to be hexagonal prifms, rounded towards the point. Cold water dilTolves ^yo^j part, and boiling water ■vTsr P"""' °^ '^'^ ^''''' Water faturated with carbonic acid diflblves -j-fsth part*. * Ftureray, According to Dr Withering, who firft difcovered itAnn.Je native, it is compofed of 80 parts of barytes and 2D of ^'-""'- '"• acid. Bergman informs us, that artificial carbonat is *' compofed of 7 parts of acid, 28 of water, and 65 of earth f. f Bergman, It is not altered by expofure to the air. i. »i. It is decompofed by the application of a very violent heat J. \DrlUfe, By compound affinity it is decompofed by the fol- lowing falts : Nitrat of alumina, Muriat of lime, : — ammonia, magnefia, alumina. 3. Carbonat of ammonia. dral cryftals, having for the moft part their two oppofite apexes truniated J. Its tafte and fmell, though much weaker, are the fame with thofe of pure ammonia. Like all the alka- line carbonats it converts vegetable blues to green, pre- cifely as pure alkalies do. It is foluble in rather Icfs than twice its weight of Sulphat of foda, lime, - — ammonia, magnefia, alumina. Nitrat of foda, . lime, ammonia, magnefia, 5. Carbonat of lime. Acetite of lime, — — magnefia, alumina. 771 This fubftance, under the Carbonat names of marble, chalk, lime Hone, &c. exills in great"^""'*' abundance in nature, varioufly mixed with other bodies. When pure, it is of a white colour, and has very little tafte. It is infoluble In pure water j but water faturated with carbonic acid dlffolves tt'oo part of it ; from this folu- tion it gradually precipitates as the acid leaves it in the form of fmall rhomboidal cryftals §. t Birgman, It is compofed, according to Bergman, of 34 partsi. 11. of acid, II of water, and 55 of lime. It fuffers little or no alteration by being expofed to the air. When expofed to heat, it firft lofes its water, and afterwards its acid feparates as the heat is increafed : But to feparate the acid completely, a very ftrong heat is required. The following falts decompofe it by compound affi- nity : Sulphat of alumina, 7 copper. _ yy^ 6. Carbonat of ftrontites. This fait, which was firft Carbonat examined by Dr Hope, is infipid, and foluble in 1536°/ ft'on- parts''"'' Part III. ^ Fouicroy^ jirtn, df Chim. li. } Bulini. Hid. ibiJ. Carboiiats. pgrto of hoiling water. It is compofed of 30,2 parts of "' 1 acid, 69,8 of ftrontites. A violent heat decompofes it *, ~ °t'v •• 7. Carbonat of maffnefia. This fait may be formed jv. 5. oy faturating the common magneda or the Ihops with 774 carbonic acid gas. Carbonat of j( diffulves in water faturated with carbonic acid; magneua. ^^^ forms by evaporation cryllals, which are traiifparent hexagonal prifms, terminated by a hexaj^onal plane ; thefe are partly in groups and partly folitary : their f BK/iMi/z/f length is about fix lines, their breadth two f. They laAlagMp. ^ygrg difcovered by Mr Butiai of Geneva. Water at the temperature of 50 diffolves j'-j- part of its weight of this fait \. When in the ftate of powder, and of courfe deprived of its water of cryftallization, it is much more inioliible ; and what is very remarkable, it is more foluble in cold than in hot water, impregna- ted with carbonic acid ^. It is compofed, according to Fourcroy, of 50 parts of acid, 25 of magnefia, and 25 of water. When expofed to the air, it efflorefces, and falls into U Fourcroy, powder||. _ When heated, it decrepitates, falls into powder, and is decompofed «(f. The following falts decompofe it by compound affi- nity : Sulphat of lime, Nitrat of lime, ammonia, Muriat of lime, alumina, Acetite of lime. 8. Carbonat of alumina. Carbonic acid is capable of diflblving alumina; for if alum be decompofed by an al- kaline carbonat, fome alumina remains dilfolved in the liquor, and may be precipitated by a heat fafTicicnt to drive off the carbonic acid *. It cannot be doubted, then, that there may be produced a carbonat of alumi- na; but the fait has never been examined with accuracy. 9. Carbonat of iron. Water faturated with carbo- nic acid diffolves Tsfo^ part of its weight of iron, which gradually precipitates by cxpofure to the air -j-. Ruft of iron is a kind of carbonat, at leaft it always contains carbonic acid. 10. Carbonat of zinc. Zinc is copioufly diffolved by water faturated with carbonic acid \. As the me- tallic oxides, when faturated with carbonic acid, do not differ materially in their appearance from pure oxides, we fhall not attempt to defcribe any of the metallic car- bonats. We fhall, however, prefent our readers with the following Table, exhibiting a view of the weight which metallic oxides gain by being faturated with this acid. By Bergman. By Wenzel. 1* ccipitateJ by C H E M I S T R y. 577 Quantity of lofs by driving off the gas by folution Acetitcs. according to Weiizel : ' » Zinc, - . . . Iron, .... Cobalt, Lead, Carbonat of -alumina. * Bergman ^ i. «z. 776 Mctillic carbonats. + Bergm.in, '•33' t UIJ. Carb. of So !a. 100 parts of ^y'eiJ;h^. Oxide of zinc, ... 160,930 iron, - - 100,250 manganefe, - 100,800 cobalt, - - 100,600 nickel, - - 100,350 lead, - - - 100,320 tin, - - . 100,310 copper, - . 100,940 bifmuth, - 100,300 antimony, - 100,400 mercury, . 1 00, 1 00 filver, - - 100,290 gold, - - - 100,060 SVPPL. VoL.I. Part I, Carb. of Po'afs. Weight. 100,774 100,863 100,304 100,345 100,884 100,224 100,395 100,062 100,288 ioo,3j6 Tin, Copper, Bifmuth, Antimony, Mercury, Silver, Gold, 0,137 0,009 0,3 >2 0,157 0,000 0,174 0,056 0,000 ■ 0,038 0,158 0,144 rn Thefe determinations differ too widely from each other to be exact. It is obvious that part of the weight mull be owing to adhering water, and very probably triple falts are formed, which mud render the determi- nation ftill more erroneous. Sect. XI. Of Acetites. The compounds which the acetous acid forms are called acetites, I. Acetite of potafs. Pliny is fuppofed, but pro- Acet'it'e of bably without any reafon, to have been acquainted withl'o'afe. this fait, becaufe he recommends a mixture of vinegar and vine afhes as a cure for a particular fpecies of tu- mor*. It was firlt clearly defcribed by Raymond Lully. * P/.m/.I, It has received a great number of names ; as, for in- >""''• ^'■''■- ftance, arcanum lartari, fecret foliated earth of tartar, ef.""'""' fentlal fait of ■wine, regenerated tartar, diuretic fait, digef- ti-ve fait of Sylvius. Its cryftals are very white, and affume the form of thin plates. It has a ftiarp warm taile. It is foluble in about ten times its weight of water at the temperature of 6o°f . It is foluble alfo in alcohol, f Bergman, According to Wenzel, 240 parts of acetous acid re-"- ?"• quire for faturation 24liths of potafs. And from the experiments of Dr Higgins, it appears that acetite of potafs is compofed of 6j,5 parts of alkali and 38,5 of acetous acid and water J. ) o„ Autout When expofed to the air it is very deliquefcent. — AdJ,f.i. When heated, it melts as readily as wax ; and if a very ftrong heat be applied, the acid is decompofed. The following falts decompofe it by compound affi. nity : Nitrat of ammonia, ■ — magnefia, alumina, bifmuth. Sulphat of foda, lime, ammonia, magnefia, alumina, Nitrat of foda, lime. mercury, Muriat of ammonia, alumina. -78 2. Acetite of foda. This fait was firft: defcribed by Acetite of Mr Baron. '<"*»• Its cryftals are ftriated prifms, not unlike thofe of fulphat of foda. It has a fharp tafte, approaching to bitter. It is foluble in 2,86 parts of water at the tempera- ture of 60" f. ^Bergman, According to Wenzel, 440 parts of acetous acid re-'*"'- quire for faturation i57^ths of foda. It is not affeAed by cxpofure to the air. When hea;ed, it firft lofes its water of cryftallization; 3 B in 378 Acetites. 179 Acttitc of • M,r:. I'ur.i.-j-jS •^ nr(rpin.t o« AccUus yUi.l, p. I88. ibji, p. 192. 5 7i5;irit of MiniJtrerus. It is too volatile to be eafilv cryftallized : It may, however, by gentle evaporation, be made to depofite iieedle-fhapcd cryftals. Mr de LafTone cryftallized it by fuWimatiou *. When the fubllmation is (low, it forms long, (lender, flatted cryftals, terminating in (liarp points, of a pearl white colour, and about an inch and eight-tenths In length f. It imprelTcs the tongue at firft with a fenfe of cold- nefs, and then of fweetnefs, which is followed by a tafte rtfembling that of a mixture of fugar and nitre, in which the fweet does not predominate over the maw- kilh tafte of the nitre J. According to Wenzel, 240 parts of acetous acid fa- turate 244 of ammonia. It is very deliqucfcent. It melts at 170°, and fu- blimes at about 2^0" §. When a watery folution of this fait is diftilled, there comes over firft a quantity of am.monia, next a quantity of acetous acid, and at laft of the neutral fait itfclf. No fuch decompofition takes place when the cryftals are diftilled by a moderate heat ||. The following falts decompofe acetite of ammonia by compound af&nity : Sulphat of alumina, Carbonat of foda, Carbonat of potafs, Nitrat of filver ^. 4. Acetite of barytes. This fait was firft formed by Mr Morveau. It is not eafily cryftallized. Morveau procured it in long prifms in groups. It has a pleai'ant, fomewhat acid tafte, and always contains an excefs of acid. It is foluble in water, and does not deliquefce when expofed to the air *. The following falts decOmpofe it by compound affi- nity : I S T R Y. Part III. According to Wenzel, 240 parts of acetous acid re- Aceiites. quire for laturation 125 of lime : according to Maret, ^^~v— ' 100 parts of acetite of lime contain 50 of lime *. From « En.-yc tne experiments of Dr Higgins, it follows, that ace- MrthoJ. tite of lime is compofed of 35,7 parts of lime and 64,3 "^""- '• S- of acetous acid and water j-. f On Acciout It is not altered by expofure to the air; at leaft ^"''. P- 47. Morveau kept fome of it for a whole year merely co- vered with paper, and even quite uncovered for a month, without its undergoing any alteration |. \ Ibid. En. Heat dccompofes it, and at the fume time partly de-0'- Mc- compofcs its acid. '* • The following falts decompofe it by compound affi- nity : Muriat of alumina, Carbonat of barytes, potafs. Sulphat of potafs, foda, lime, . ammonia, magnelia, alumina. Nitrat of alumina, Muriat of potafs, loda, lime, ammonia, maguefia, alumina. Carbonat of potafs, foda, ammonia. 1^1 Acciite of Jinie. + Plinii, I. ixivi. c, a4- Nitrat of potafs, foda, lime, . . ammonia, magnefia, 5. Acetite of lime. This fait was firft defcribed ac- curately by CroUius. The ancients, however, ufed a mixture of lime and vinegar in furgery f . It cryftallizes in fine needles, of a glofly appearance like falin. Its tafte is bitter and four, becaufe it has an excefs of acid. It is foluble in water. Sulphat of foda, ammonia, magnefia, alumina. Nitrat of ammonia, magnefia, alumina, Muriat 6f ammonia, 6. Acetite of ftrontitcs. foda, ammonia, magnefia, alumina. 78i This fait was firft formed Acetite oi by Dr Hope. It forms fmall cryftals, which are not ^'°'"""- affefted by expofure to the atmofphere. 49 parts of it are foluble in 120 parts of boiling water : It feems to be nearly as foluble in cold water. It renders vege- table colours green ^. § ^^ Ko/f, 7. Acetite of magnefia. This fait was firft mention- -^^""-^ ^'''"'• ed by Mr Wenzel. 1^3 It is not cryftallizable ; but forms by evaporation a Acetite of vifcid mafsjl. magnefia. It has a fweetifh tafte ; leaving, however, a fenfe of-; .'J?'"'"'' bitternefs^f. _ ^ .W„mb, It is very foluble both in water and alcohol *. ioiJ. According to Wenzel, 240 parts of acetous acid re- * Brrgman, quire for faturation 1 z^^Jths of magnelia. '' ^ ' When expoied to the air, it deliquefces. Heat de- compofcs it. The following falts decompofe it by compound affi- nity : Sulphat of ammonia, alumina, Nitrat of ammonia, alumina, Muriat of ammonia, alumina. Carbonat of barytes, — — potafs, foda, ammonia, alumina. 784 8. Acetite of alumina. This fait can only be form- Acetite ot ed by digefting acetous acid on alumina recently preci-*'""""*" pitated. By evaporation needle-ftiaped cryftals are obtained, which are very deliqucfcent. According to Wenzel, 240 parts of acetous acid Require 20-Tths of alumina for faturation. This fait is decompofed by compound affinity by the following falls : Nitrat of ammonia, Carbonat of potafs, Muriat of ammonia, foda, Carbonat of barytes, ammonia. ^j^ g. Acetite of jargonia. This fait may be formed by Acetite of pouring acetous acid on newly precipitated jargonia. J^irgonia. It has an aftrlngent tafte. It does not cryftallize ; but when evaporated to drynefs, it forms a powder, which | Khprott, does not attraft moifture from the air as acetite of alu-Jo^irn.at uiina does t. It is very foluble in water and in alco- ^''yf- xxx»i hol.'8^- Part III Acetires. Aceiite of zinc. C H E M I liol. It is not fo ciifily dtcompofed by heat as nitrat of jaigonia, probably becaufe it dots not adhere fo ftrongly to water *. 10. Acctitc of iron. — This fait was mentioned by Schroedcr and Juntkcr. It is coinpofed ol acetous acid and brown oxide of iron. Its folution forms by gentle evaporation fmall oblong cryttals ; but the greattit part of the fait affumes the ■f Wtnzel. form of a gelatinous mafs f. It has a fweetifh ftyptic taile. According to Werzel, ^^o parts of acetous acid re- quire for faturation l86i of iron. Heat decompofes this fait ; and it feems alfo to be gradually deconipof>:d by expofure to the air. 11. Acetite of zinc. — This fait was firft mentioned by Glauber. Its cryllals are rhomboidal, and fometimes hexagonal plates, of a white colour, and the appearance ot talk. It is foluble in water. According to VVenzel, 240 parts of acetous acid require for faturation I95yths of zinc. It is not altered by expofure to the air. Heat de- compofes it. When thrown upon burning coals, it ex- plodes with a blue flame. 12. Acetite of manganefe. — This fait is not cryftal- lizable ; and when evaporated to drynefs, it deliquefccs. Is it not an acetat ? 1 3. Acetite of cobalt. — This fult is deliquefcent. Its folution is of a fine red colour while cold; but becomes blue by being heated, and it recovers its former colour on cooling. According to Wenzel, 240 parts of ace- tous acid require for faturation 24iyths of cobalt. 14. Acetite of nickel. — ['his fait forms rhomboidal cubes of a green colour J : They are not deliquefcent : Their tafte is fweet §. I ?. Acetite of lead. — This fait is mentioned by Ifaac S T R Y. 379 788 Acetite of cobalt. 7S9 Acetite of nickle. J Bergmtin. § Mound. 790 Acente of Hollandus and Raymond Lully. It is compofed of lead. acetous acid and white oxide of lead. It was formerly called fugar of lead, fugar of Saturn, fait of Saturn, -vinegar of Saturn, extraH of Saturn, &c. Its cryitals are flat parallelopipeds, terminated by two inclined planes approaching each other. It has a fweet and fomewhat allringent tafte. It is not very foluble in water ; but acetous acid dif- folvcs it abundantly. According to Wenzel, 240 parts of acetous acid re- quire for faturation 503 of lead. When expofed to the air it becomes yellow, but un- dergoes no other alteration. Heat decompofes it by deftroying the acid. When riiftilled, the refidutim takes tire fpontaneoufly on expo- fure to the air. Paper dipped into acetite of lead forms excellent matches, which are not fubjtft to go out, and which bum very flowly. The following falts decompofe it by compound affi- nity : Muriat of ammonia, Phofphat of ammonia, Sulphat of copper, Oxalat of potafs {{, Phofphat of fdda, Malat of potals ^. 16. Acetite of tin. — This fait was firlt dcfcrihed by Lemery. Its cryftals are prifmatic needles in groups *. Ac- cording to Wenzel, 240 parts of acetous acid require for faturation j-jV o^ tin. 791 Acetite of tin. 17. Acetite of copper Thib fait was known to the Acetite. ancients, and various ways of preparing it are defcribed * by Pliny *. It was formerly known by the names of,\„ti,jof crji^/ials of Venus and verdigrife. copper. It is of a deep green colour. Its cryftals are rhom- *Lib.xxxiv. boids. '• "• It has a difagreeable coppery tafte. It is foluble in water and in alcohol. According to Wenzel, 240 parts of acetous acid re- quire i6-|rth of copper ior faturation. It efflorefces when expoled to the air. Heat de- compofes it. It is ufcd in painting. 753 18. Acetite of bifmuth. — This fait feems to have been Acetite of firft mentioned by Geoffroi. He called 'il fugar ofl/fmuth.^''^'^^'''-^- It is moll eafily procured by mixing together the fo- lutions of nitrat of bilmuth and acetite ot potaf?. It forms brilliant, talky, filvery cryftals. It has a fweetifti tafte. According to Wenzel, 240 parts of acetous acid require for faturation ij^-ths of bifmuth. It does not deliquefce when expofed to the air. Heat decompofes it. 79+ 19. Acetite of antimony. — It yields with difficulty '^'-"•'"^ °^ fmall cryftals f . According to Wenzel, 240 parts of, rr"",/' acetous acid require for faturation i |d of antimony. -^^ 20- Acetite of arfcnic. — This fait forms fmall cry-Acetite of ftals in grains, hardly foluble in water J. arlenic. 21. Acetite of mercury. — This fait is mentioned by jnh"'"' Schroeder. Acotitc of Its cryftals are fmall thin plates. mercury. It has a difagreeable tafte, and excites coughing. It is hardly foluble in water. According to Wen- zel, 240 parts of acetous acid require for faturation 240-Tths of mercury. When expofed to the air it becomes black, owing tt> the reduction of the oxide of mercury. Heat decom- pofes it. 797 2 2 Acetite of filver. — This fait was perhaps firft ^""''"^ defcribed by Margraf. It is beft formed by dropping acetite of foda or pot- afs into a faturated folution of nitrat of fdver ^. 5 Mant, It forms fmall oblong cryftals, eafily diffolved in wa-""'^- tcr f . It has a (harp tafte. f Margtaf. According to Wenzel, 240 parts of acetous acid re- quire for faturation loi^ths of filver. Heat decompofes it. It is decompofed by muriat of magnefia ^. f Ber^man^ 23. Acetite of gold. — This fait is mentioned by 79^ Sehroeder and Juncker. '^""'^ "^ 24. Acetite of uranium. — This fait was firft formed -nn by Klaproth. Acititc of Its cryftals are regul.ir four-fided flender prifms, ter.""'""™- v minated at both ends by regular quadrilateral pyramids: they are tranfparent, and of a beautiful topaz yellow colour. Heat decompofes them : and what is Angular, if they be heated gradually red hot, the oxide which remains retains nearly the form of the cryftals *. * '^''•'^''f-'* The compounds into which the acetic acid enters are"" ''^'"""• railed rt(-<7(//^. They are fo imperfcilly known at pre- .^g^^^j^s. fent, that we fliall not attempt a defcriptlon of them. Sect. XII. Of 0:«''. 19. Tartrite or tin. Unknown. The tartrite of pot- afs and tin, compofed of tartar and oxide of tin, is ca- pable of cryllallizing. 20. Tartrite of copper. This fait is beft formed by pouring tartarous acid into the folutions of muriat or fulph.at of copper ; it precipitates in the form of blue cryftals *. * Birgman. This fait forms the beft kind of the pigment called Bnwfivick grem\. t Limhardi, 21. Tartrite of potafs and copper. This triple fait is alfo in the form of blue cryftals. 2 2. Tartrite of bifmuth. Small cryftalline grains J. ^ ^'rgnan, 23. Tartrite of antimony. This fait has never been examined with attention. 24. Tartrite of potafs and antimony, or tartar emetic. To this fait, which is perhaps the moft powerful emetic known, a great deal of attention has been paid, and a vaft number of methods have been tried to prepare it. Thefe methods have been already defcribed in the En. cyclopsedia. It appears from the experiments of Mr Biadhein),. Chim 382 C H E M I Bi:idhciin, tl.at if this fait he carefully prepared, the difference that refults from the ufe oi different pKides ia • Ann.Jt not l"o jrreat as no'ght have heen expected *. It was lirll made known by Adrian in 1631. It is a triple fait, compofed of tartar and white oxide of an- timony. It is of a while colour and tranfparent. Its cryftals are trihedral pyramids. It diflolvcs in (o parts of cold water, and in a fmaller proportion of hot water. It is decompofed by lime - and alkalies, iron, &c. Care ought therefore to be taken to ufe only diftilled water when it is adminiftered as a medicine. 25. Tartrite of arfenic. This fait forms prifmatic f Brrgman, cryftals very like tliofe of oxalat of aricnicf. »'• =i'i- 26. Tartrite of mercury. A yellow powder. 27. Tartrite of potafs and mercury. This triple fait } Moitnei. cryftallizes J. Sect. XTV. 0/ Citrats. The compounds into which the citric acid enters have been denominated citrats. Thefe falts are at prefent very imperfeftly known. Mr Dize has promifed foon to fupply this defeft J. 1. Citrat of potafs. This fait does not cryftallize. It has a cooling faline tafte, and deliquefces when ex- pofcd to the air. 2. Citrat of foda. This fait does not deliquefce. It has a mild, pleafant, cooling tafte I|. According to Scheele, it does not ci7ftallize. 3. Citrat of ammonia. This fait cryftallizes ia thin needles. It has a cooling and moderately faline tafte ^. The ammonia is feparated by the application of heat*. 4. Citrat of barytes. This fait is fcarcely foluble in water. It afl'umes the form of a white powder f . It is foluble in citric acid. 5. Citrat of lime. This is a white powder, fcarcely foluble in water J. 6. Citrat of magnefia. Does not cryftallize. It forms a gummy fahne mafs very foluble in water §. 7. Citrat of alumina. This fait is fcarcely foluble in water, 8. Citrat of iron. A folution of a brown colour. 9. Citrat of copper. A green gummy mafs. 10. Citrat of mercury. This fait may be formed by pouring citric acid into nitrat or acetite of mercury. It is a flaky fait, of a brickduft colour, more or lefs red 11. Sect. XV. Of Malati. The compounds into which the malic acid enters are called malats. This clafs of falts was firft difcover- cd by Scheele. They are no better known than the ci- trats. 1. Malat of potafs. T 2. Malat of foda. J- Thefe falts are deliquefccnt^. 5. Malat of ammonia. J 4. Malat of lime. Small irregular cryftals. _ They require a large quantity of boiling water for their folu- tion. Wiih excefs of acid they are readily foluble in cold water |. They are infoluble in alcohol J. 1 Id 5- Malat of barytes. The properties of this fait re- fcmble pretty much thofe of malat of lime §. ''''■ 6. Malat of magntfia. Dtliquefcent H- S T R Y. Part III. ^ "Journ. dt J'hf- ' -94, Alkaline citrats. II D, Do- nald Monro, Phil. Irarf. SI- t Dob/on. 814 Earthy ci- •«ra's. \u \IJ. J u. 8>S Metallic utrats. I Vi: 816 Malat!:. zable Malat of iron. A brown folution, not ei7ftalli- LaflatJ. 8. Malat of zinc. This fait forms beautiful cryftalsf. * fj"'''' Sect. XVI. Of LaSuts. 817 The neutral falts formed by the combination of the Ladtats. laftic acid with various bafes are called Liciats. They were firft; difcovered by Scheele. 1. I.idat of potafs. A deliquefcent fait, foluble in alcohol J. I Srirclt on 2. Laflat of foda. This fait does not cryftallize. It ^'"• is foluble in alcohol J. , ... , 3. Laftat ef ammonia. Cryftals which deliquefce. Heat feparates a great part of the ammonia before de- ftroying the acid. 4. Laaat of barytes. T Thefe falts deliquefce ||. The 1| UiJ. 5. Laftat of lime. |> laftat of lime is foluble in al- 6. Laftat of alumina, j cohol 5[. ^ Ibid, 7. Laftat of magnefia. Small deliquefcent cryftals*. ^ ,,.. 8. Laftat of iron. A brown folution. 9. Laftat of zinc. Cryftals f. \ Ibii. Thefe falts have a very ftrong refemblance to malats. The only difference which Scheele obferved was, that the malat of lime was infoluble in alcohol, while alcohol diflblved laftat of lime. Sect. XVII. Of Saccholais. 818 The compounds into which the faccholaftic acid en- saccholats. ters are csWeA facikolats. They alfo were firft difcover- ed by Scheele. 1. Saccholat of potafs. Small cryftals, foluble in eight times their weight of boiling water J. j '^chtrl! on 2. Saccholat of foda. The fame ; foluble in five Sugar of times their weight of boiling water J. Milt. 3. Saccholat of ammonia. A fait which has a fourifh ? ""'• tafte. Heat feparates the ammonia ^. ^ Ibid. 4. Saccholat of barytes. "J 5. Saccholat of lime. (Thefe falts are infoluble 6. Saccholat of magnefia. fin water*. * liid. 7. Saccholat of alumina. J Sect. XVIII. Of Gallats. The compounds into which the gallic acid enters are q-u'? denominated gallats. They were firft attended to by the Dijon academicians and by Scheele. 1. Gallat of potafs. T We only know that thefe 2. Gallat of foda. > compofitions are poffible, 3. Gallat of animbnia. J ''"'^ 'hat their properties are different from thofe of all other falts. 4. Gallat of barytes. 1 Thefe falts are foluble in wa- ' J. Gallat of lime. J ter, cfpecially when there is excefs of acid. 6. Gallat of magnefia. This fait is a yellow powder, foluble in water and in alcohol *. * * Bartboldl 7. Gallat of alumina. This fait, according to Bar- yi„„. ji. tholdi, exifts ready formed in nut galls. It is very fo- '.tim. xii. luble in water. ^oi- 8. Gallat of iron. This fait, which Mr Prouft has difcovered to be formed of gallic acid and brown oxide of iron, is of a black colour, and does not ieem capable of cryftallizing. It is foluble in the three mineral acids, and by that means is deprived of its black colour. It is to this fait that ink partly owes its black colour. Gallat of iron is decompofed by alkalies. We ftiall not attempt any farther account of this clafs of Part III. C H E M Benzoats. of fait s. Scarcely any adJItJon has yet been made to ' — V ■ the experiinents of ticheele which have been given al- ready in the article CunMiSTRV, Encyrl. Sect. XIX. OJ Benxoals. The compounds into which the benzoic acid enters have been called len%oats. 1. Benzoat oF potafs. This fult forms pointed fea- thery cryltals. It has a faline (hnrp taile. It is very fo- luhle in water. It deliquefces when expoied to the air*. 2. Benzoat of foda. Tlie cryftals of this fait are lar- ger, but its talle is the fame with that of benzoat of potafs. It is alfo very fuluble in water. It cfflorefces in the air f. 3. Benzoat of ammonia. This fait cryftallizes with difficulty. Its cryftals are feather-fhaped. It deli- quefcesj. 4 Benzoat of lime. This fait forms white, (hining, pointed cryftals, of a fweetifti tafte, and not eafily fo- I S T R Y. .38-3 8ao Alkaline benzoacs. i liia. i UiJ. Earth)' bcn7iiits § I.id. luble in water ^. 5. Benzoat of magnefia. Feather-fhaped cryftals, of ■}■ Ibid. a fliarp bitter tafte, and eaiily foluble in water -|-. Sii 6. Benzoat of alumina, an aftringent fait. Metallire 7. Benzoat of iron. This fait forms yellow cryftals. berjzoitf. \[ Jjaj a fvveet tafte. It is foluble in water and alcohol. <[ Trcmmf- It efflorefccs in the air. Heat difengages the acid^. Jf.', " ■ 8. Benzoat of zinc. This fait forms arborefcent cry- ,, ' ftals. It is foluble in water and alcohol. When expo- * IJ.iiid. fed to the air it is diffipated. Heat decompofes it*. 9. Benzoat of manganefe. This fait, which is form- ed of benzoic acid and white oxide of manganefe, cry- ftallizes in fmall fcales. It difTolves readily in water ; with difficulty in alcohol. It is not altered by expofure + IJ.aiJ. to the airf. \ld.ibU. 10. Benzoat of cobalt. Flat cryftals J. 11. Benzoat of lead. Very white cryftals, foluble in water and alcohol. They are not altered by expofure § IJ.iiiJ. to the air. Heat difengages the acid j. 12. Benzoat of tin. This fait may be formed by pouring ben/.oat of potais into a folution of tin in the nitro-muriatic acid. The benzoat of tin is precipitated. It is foluble in hot water, but infoluble in alcohol. Heat D JJ. ihid. decompofes it ||. 13. Benzoat of copper. Small cryftals of a deep green colour. They arc with difficulty foluble in wa- 1 Id. Hid. ter, and not at all in alcohol ^. 14. Benzoat of biimuth. This fait forms white reedle-ftiaped cryftals. They are foluble in water, and in a very fmall proportion in alcohol. They are not altered by expofure to the air. Heat decompofej * Id. Hid. them*. 15. Benzoat of antimony. Cryftals which efflorefce ■f-IJ ibid, in the air, and are decornpofed by heat \. 16. Benzoat of arfenic. Small feather-fhaped cry- ftals. It is foluble in hot water, but cryftallizes in the cooling. A moderate heat fublimes it ; a ftrong beat decompofes it. Sulphur decompofes it. It is not de.^ \:U.ilid. compofed by alkalies ^i- 17. Benzoat of mercury. A white powder. It is infoluble in water, but diifolves in a fmall quantity in alcohol. It is not altered by expofure to the air. A fmall heat fublimes it ; a greater decompofes it. It is jf.ZJ.iiid. decornpofed by fulphur §, i&. Benzoat offilver. This fait is foluble in water, and alfo in a very fmall proportion in alcohol. It is Cmipho- not altered by expofure to the air, but the rays of the ^ " ""' fun render it brown. Heat difengages its acid *. . jj_ ,i,ij_ 19. Benzoat of gold. Small irregular cryftals, not eafily foluble in water ; infoluble in alcohol. It is not altered by expofure to the air. Heat decompofes it f. ^ Id. ihid. 10. Benzoat of platinum. This ialt forms fmall brownilli cryftals, with difficulty foluble in water ; not foluble in alcohol. When expofed to heat, it is decorn- pofed, and there remains behind a brown powder J. } IJ.iiid. Sect. XX. Of Succinats. The neutral falts, formed by the combination of the fuccinic acid with various bafes, have been called /uffi- JUllS. We ftiall not defcribe thefe falts, as we could not add much to the account given in the Appendix to the ar- ticle Chemistry in the Encycl. That account was ta- ken from Mr Kier's Chemical Dictionary, and tliat gentleman borrowed it from Leonhardi. Sect. XXI. Of Camphorais. The neutral falts into the compofition of which cam- phoric acid enters, have been denominated camphorati- The only chemift who has hitherto examined them is Bouillon la Grange ; his experiments have been publiffi- ed in the 27th volume of the Annahs de Chimie. 1. Camphorat of potafs. To prepare this fait, car-,, \ bonat ot potais is to be dillolved in water, and the folu. „f p„t„f, tion faturated with camphoric acid. When the effervef- cence is over, the liquor is to be evaporated by a gentle heat to the proper confiftence, and cryftals of campho- rat of potafs will be depofited when the liquor cools. Camphorat of potafs Is white and tranfparent ; its cryftals are regular hexagons. Its tafte is bittenTa and (lightly aromatic. Water at the temperature of 60° diftblves -' jth part of Its weight of this fait ; boiling water diirolves ^th part of Its weight. It Is foluble in alcohol, and the folution burns with a deep blue flame. Wlien expofed to moift air, it lofcs a little of its tvanfparency, but in dry air it fuff^ers' no change. When expofed to heat it melts, fwells, and the acid is volatilized in a thick fmoke, which has an aromatic odour. Before the blow-pipe it burns with a bhie flame, , and the potafs remains behind in a. ftate of purity. By compound affinity this fait is decompofed by Nitrat of harytes. All the falts whofe bafe h lime, Nitrat of filver, Sulphat of iron, Muriat of tin, lead §. { BoailUn 2. Camphorat of foda. This fait may be formed •^'' '^'"'"'.f'""- precifcly in the fame manner with the camphorat of^f"''^ .. potafs. ^. It is white and tranfparent ; Its taft.c is fomewhat Sxi bitter ; its cryftals are irregular. Camphorat Water at the temperature of 6g° diflolves lefs than"^ '^"''^" -s-i^th part of its weight of this fait ; boiling water dif- folves -J-tli of its weight. It is alfo foluble in alcohol. Wiienespofed to the air it lofes its tranfparcncy, and eftlorefcrt CHEMISTRY. efflorefces flightly, but is never completely reduced to powder. Heat produces the fame effeft upon it as on cam- phorat of potafs : tlie acid burns with a blue flame, which becomes reddifh towards the end. Bv compound affinity it is decompoled by * Btutllon ia Grange, Jin*, de Ctim.avVl. 96. 815 Camphorat of ammo- tiia. Nitrat of lime, filver, Muriat of magnefia, barytes, alumina, Muriat of lime, • • iron, Sulphat of alumina, iron : and ma- ny other fdks with me- •{• 7iiJ. 8j6 Camphorat of barytes. I Bouillon La Grange, ibid. p. ZS. Camphorat •flime. tallic bafes *. 3. Camphorat of ammonia. This fait may be pre- pared by diflblving carbonat of ammonia in hot water, and adding camphoric acid flowly till the alkali is fatu- rated. It mull then be evaporated with a very mode- rate heat, to prevent the difengaging of ammonia. It is very difficult to obtain this fait in regular cry- ilals. When evaporated to drynefs, there is obtained a folid opaque mafs of a fliarp and bitterith tafte. Water at the temperature of about 60' diffolves near- ly Tstfth part of its weight of this fait ; boiling water diffolves yd of its weight : But this and the two falts above defcribed are a good deal more foluble when there is excefs ot bafe. ♦It is entirely foluble in alcohol. When expofed to the air it attrads moifture, but not in fufficicnt -quanuty to enable it to alTume a liquid form. When expofed to hent it fwcUs, melts, and is con- verted into vapour; before the blow-pipe It burns with a blue and red flame, and is entirely volatilized. Mod of the calcareous falts form triple falts with camphorat of ammonia. It decompofes in part _all the aluminous falts except the fulphat of alumina f . 4. Camphorat of barytes. In order to prepare this fait, barytes is to be diilblved in water, and camphoric acid added to the folution ; the mixture is then to be boiled, and afterwards filtered and evaporated to dry- nefs. Camphorat of barytes does not xrryftallize; when the evaporation is conducted llowly, the fait is depofited in thin plates one above another, which appear tranfpa- rent while immerfed in the liquor, but become opaque whenever they come into contaft with the air. It has very little tafte, though it leaves at laft upon the tongue a flight impreffion of acidity mixed with bit- ternefs. Water diffolves only a very fmall quantity of this fait, boiling water being c:ipable of taking up only g^Tsth part of it. It is not altered by expofure to the air. When expofed to heat it melts eafdy, and the acid is volatilized. When the heat is confidcrable, the acid burns with a lively blue flame, which becomes red and at laft white. It is decompofed by Nitrat of potafs, foda, lime, ammonia, and magnefia. Muriat of lime, potafs, alumina, and magnefia. All the fulphats. Carbonat of potafs and foda. Phofphat of potafs, foda, and ammonia*. 5. Camphorat of lime. This fait may be prepared by dropping into lime-water cryftallized camphoric acid. ZLim. xivii. Part III. The mixture is then to be made boiling hot, paffed Caiipho, through a filter, and evaporated to about \\\\% of its "W- volume. On cooling, camphorat of lime is depolited. » ' It has no regular fliape ; but if the evaporation has been properly condufled, it is in plates lying one above another. It is of a white colour, and has a taft.e flightly bitter. Water at the temperature of 6o» diffolves very little of this fait; boiling water is capable of diifolving about T^^^th part of its weight of it. It is iufoluble in alco- hol. It is compofed of 43 parts of lime, 50 of acid, and 7 of water. When expofed to the air it dries and falls into pow- der. When expofed to a moderate heat It melts and fwells up : when placed on burning coals, or when iieated m clofc veffels, the acid is decompofed and volatilized, and the lime remains pure. When fulphuric acid is poured into a folution of this fait, it produces an in foluble precipitate; nitric and mu- riatic acids precipitate the camphoric acid. It is decompofed by compound affinity by Carbonat of potafs, Nitrat of barytes, Muriat of alumina, Sulphat of alumina, Phofphat of foda *. • Bcu'itln 6. Camphorat of magnefia. This fait may be pre- i" Grange, pared by pouring water on carbonat of magnefia, and ■f ''"• * then adding cryftallized camphoric acid : heat is then applied, the folution is filtrated, and evaporated to dry- SiS neis. The fait obtained is diffolved in h jt water, paffed Camphorat through 3 filter, and evaporated by means of a mode-"' "'^gne- rate heat till a pellicle forms on the furfice of the folu- tion. On cooling, the fait is depofited in thin plates. The fecond folution is to remove any excefs of magne- fia that may happen to be prefent. This fait does not cryftallize. It is white, opaque, and has a bitter tafte. It is fcarcely more foluble in water than camphorat of lime. Alcohol has no aftion on it while cold, but when hot it diffolves the acid and leaves the magnefia ; and the acid precipitates again as the alcohol cools. When expofed to the air it dries and becomes cover- ed with a little powder ; but this effect is produced flowly, and only in a warm place. When this fait is placed on burning coals, the acid is volatilized, and the magnefia remains pure. Before the blow-pipe it burns like the other camphorats with a blue flame. The nitrats, muriats, and fulphats, do not complete- ly decompofe this fait, if we except the nitrat of lime and muriat of alumina f . {Id. ind. 7. Camphorat of alumina. To prepare this fait, alu- 819 mina, precipitated by means of ammonia, and well wafti- *"J'"j'P''?"' ed, is to be mixed with water, and cryftals of campho- ric acid added. The mixture is then to be heated, fil- tered, and concentrated by evaporation. This fait is a white powder, of an acid bitterifli tafl;e, leaving on the tongue, like moft of the aluminous falts, a fenfation of aftringency. Water at the temperature of 60" diffolves about -r^tli part of its weight of this fait. Boiling water diffolves it rart in. CHEMISTRY. 385 Suherats. ** Bouillon ixi GmngCy jimn. de dim. xxvii 34- Suherat of potal's. ■^ v. iby. xxii). 52. Sulierat of foda. } /y. iiU p. 5.!- Suberat nf aranionla. P-S5. i>33 Sulieriit of barytes. II IJ. ibid. p. 5J. 834 Suberat of lime. ^ W. ibiJ. p. 54- 835 Suberat of magnefia. it in confiderable quantities; but It precipitates again as tlie folution cools. Alcohol, while cold, difTulves it very fparingly ; but when hot it dilTolves a confiderable quantity of it, which precipitates alio as the folution cools. This fait undergoes very little alteration in the air ; but it rather parts with than attradls moillure. Heat volatilizes the acid; and when the fait is thrown on burning coals it burns with a blue flame. It is decompofed by the nitrats of lime and ba- rytes *. Sect. XXII. Of Suherats. The falls formed by the fuberic acid have obtained the appellation oi fubtrats. They have hitherto been examined only by Bouillon la Grange. 1. Suberat of potafs. — This fait ought to be formed by means of cryllullized carbonat of potals. It cryftallizes in prifms, having four unequal fides. It has a bitter faltifh talle, and it reddens vegetable blues. It is verv foluble in water. Caloric melts it, and at laft volatilizes the acid. It is decompofed by mod of the metallic falts, and by fulphat of alumina, muriat of alumina, and of lime ; nitrat of alumina and of lime ; and phofphat of alu- mina \. 2. Suberat of foda. — This fait does not cryftallize. It reddens the tinfture of turnfole. Its tafte is flightly bitter. It is very foluble in water and in alcohol. It attrads moillure from the air. Caloric produces the fame effeft on it that it does on fuberat of potafs. It is decompofed by the calcareous, aluminous, and magnefian falts |. 3. Suberat ol ammonia. — This fait cryftallizes in pa- rallelopipeds. Its tafte is faltifti, and it leaves an im- prefGon of bitterncfs : It reddens vegetable blues. It is very foluble in water. It attracts moifture from the air. When placed upon burning coals, it lofes its water of cryftallization, and fwells up ; and before the blovv-pipe it evaporates entirely. It is decompofed by the aluminous and magnefian falts J. 4. Suberat of barytes. — This fait does not cryftallize. Heat makes it fwellup, and melts it. It is fcarcely fo- luble in water except there be an excefs of acid. It is decompofed by moft of the neutral falts, except the barytic falts and the fluat of lime {|. 5. Suberat of lime. — This fait does not cryftallize. It is perfectly white : It has a faltifh tafte : It does not redden the tinfture of turnfole. It is very fparingly foluble in water except when hot; and as the folution cools moft of the fait precipitates again. When placed upon burning coals it fwells up, tlie acid is decompofed, and there remains only the lime in the ftate of powder. It is decompofed by The milriai of alumina, The carbonats of potafs and foda, The fluat of magnefia. The phofphats of alumina and foda. The borat of potafs, All the metallic folutions ^. 6. Suberat of magnefia. — This fait is in the form of a powder :. It reddens the tinfture of turnfole. It has a Suppt. Vol. I. Part I. and attrafts fome Piuffiau t U itii, P-i7- bitter tafte : It is foluble in water, moifture when expofed to the air, • When heated it fwells up and melts : before the blow-pipe the acid is decompofed, and the magnefia re- mains in a ftate of purity. It is decompofed by Muriat of alumina, Nitrat of lime and alumina, Borat of potafs, Fluat of foda, Phofphat of alumina *. • Bouillon 7. Suberat of alumina. — This fait does not cryftallize. f^* Grange, When its folution is evaporated by a moderate heat in-^""'* . . a wide veflel, the fait obtained is of a yellow colour, ' tranfparent, having a ftyptic tafte, and leaving an im- g^$ prelTion of bitternefs on the tongue. When too much Suberat of heat is employed it melts and blackens. It reddens the al"n>ina. tinfture of turnfole, and attrafts moifture from the air. Before the blow-pipe it fwells up, the acid is volatilized and decompofed, and nothing remains but the alumina. It is decompofed by The carbonats of potafs and foda. The fulphat of iron. The muriat of iron. The nitrats of filver, mercury, and lead \. t '^^ '^''• Suberic acid forms alfo compounds with the oxides of filver, mercury, lead, copper, tin, iron, bifmuth, arfenic, cobalt, zinc, antim(«'iy, manganefe, and molybdenum ; moil of which are incryftallizable, and have an excefj of acid J. Sect. XXIII. Of PrufmH. The compounds into which the pruffic acid enters are called Prufflals. Thefe fubftances, the moft important of which are triple falts, have fomethiiig very peculiar in their affi- nities. The pruflic acid appears to have a ftronger af- finity for alkalies and earths than for metals, at leaft thefe fubftances are capable of decompofing metallic prufliats ; yet acids fcarcely decompole the metallic prufliats, while the weakeft acid known decompofes the prufliats of al- kalies and earths. Thefe phenomena have not yet been fatisfadlorily accounted for. 1. Pruffiat of potafs. 1 r^^^^^ ^^,^^ ^^^^^ ^_.^ ob- Alkaline 2. rrumat 01 lona. J pruILats. tained pure by Mr Scheele. They are foluble in wa- ter ; but they are of little ufe, as mere expofure to the air decompofes them. 3. Pruifiat of ammonia. — This fait has the fmell of ammonia. It is very volatile and as eafily decompofed as the other two. 838 4. Pruflidt of lime. — This fait is foluble in water. Earthy It is alfo decompofed by expofure to the air. prufliats. 5. Pi ufliat of barytes. 6. Prufliat of magnefia. lublc in water, and decompofed by all acids. Pruflic acid does not combine with alumina. 839 7. Prufliat of iron, or Pruffian blue. — This fubftance Pfultian is compofed, as Mr Prouft has fliewn, of the pruflic acid and brown oxide of iron. With the green oxide the pruflic acid forms a white compound, which, how. ever, becomes gradually blue when expofed to the at- mofphere, becaufe the oxide abforbs oxygen, and is con- . verted into brown oxide §. J Nicial- Prulfiat of iron is a deep blue coloured powder. It j, ^^^, 3 C 16 ."37 } Thefe falts are alfo fo- 386 CHEMISTRY. Part III, Prufliat' (40 An.nities rf the priif- £c acid ex- f'liined. S4T Pfoferties «f prulTian aliUU. is iiifoluMe in Vfater, and fcarcely foiuble in acids. It is compoltd, according to the tnoit accurate experiments hitherto made, of equal parts of oxide of iron and pruf- fic acid. It is not affefted by expofure to the air. Heat dtcompofcs it by deftroying the acid, and the oxide of iron remains behind. The Pruflian blue of commerce, befides other impuri- ties, contains mixed with it s great quantity of alumina. Its ufe as a pigment, and the attempts which have been made to introduce it as a dye, arc well known. Prufliat of iron may alfo exill in another ftate : It may have a fiiperabundance of oxide ; its colour is then more or lels yellow. '1 o this Hate it may be reduced by digefting it with alkalies or any of the alkaline earths. Thcfe fubftances deprive it of part of its acid, but not of the whole. This yellow pruffiat is foiuble in acids. Were vfe to attempt an explanation of this, and the other phenomena which the pruflic acid difplays in its combinations, we would conjeAure, that this yellow prufliat is the fubflaiice formed by the direft combina- tion of brown oxide of iron and pruflic acid, and that the blue prufliat is formed of the yellow prufliat combi- ned as an integrant with pruflic acid : That the affinity between the pruflic acid and oxide of iroii is much ftrong- er than that between yellow prufliat of iron and pruflic aeid ; that therefore alkalies and earths have a ftronger affinity for pruflic acid than the yellow pruflTiat has, hut a much weaker afiinity than oxide of iron, and perhaps fvery other oxide ;— hence the apparent fupcriority of alkalies and earths in fome cafes, while in others they appear very inferior. We would fuppofe, then, that the pruflic acid has a much ftronger affinity for oxide of iron, and perhaps for all other oxides, than for other bodies ; that the prulfiats, thus formed, are capable of GombiiiiTig with pruflic acid ; but that their affinity for it is much Icfs than that of the alkalies and earths. This Gonjefture is fupported by all the plienomena at prefent known ; it would remove all the apparent anomalies which the combinations of this fmguJar acid prefent, and reduce the whole of them under the known laws of afiinity. S. Prufliat of potafs and iron, commonly called Pruf- Jmn alkali, or PruJJian tejl. This fubllance is a triple fait, compofed of pnifiic acid, potafs, and oxide of iron combined together. To chcmifts and mineralogift:s it is one of the moft important inftruments ever invented ; as, when properly prepared, it is capable of indicating ■whether any metallic fubilance (platinum excepted) be prefent in any foluticn whatever, and even of pointing out the particular metal, and of afcertaining its quan- tity : This it does by means of a compound affinity, which, after what has been faid above, may be eafily underllood. The Pruflian alkali may be conceived to be a combination of two fubftances, prufliat of pot- afs and blue prufliat of iron. Now every metallic oxide has a ftronger afSnity for pruflic acid than potafs has fand, in faft, feems to have a ftronger affinity for it than for any other fubftance). If, therefore, there hap- pen to be any oxide in the folution, it immediately feizes the pruflic acid with which the potafs is combined, and by that means decompofcs the triple fait. A prufliat of the particular metal is formed, and, as moil prufliats of metals are infoluble, it is precipitated ; and it indi- cates by its colour the particular metal, and by its weight the quantity of metal that happens to be pre- Prufliatt, feut. At the fame time the blue prufliat of iron is al. ' * * fo precipitated, and its weight muft be deducted from the quantity of the precipitate. In order to be certain of the accuracy of thefe re- fults, it is neceffary to liave a Pruflian alkali perfeftly pure, and to be certain before hand of the quantity, or rather of the proportions of its ingredients. To ob- tain a teft of this kind has been the objedt of chemifts ever fince the ditcoveries of Macquer pointed out its importance. It is to the ufe of impure tefts that a great part of the contradiftory refults of mineralogical analyfes by different chemifts is to be afcribed. There are two * ways in which this teft may be ren- « See Kir. dered impure, befides the introduftion of foreign in- y"'' Min, gredients, which we do not mention, becaufe it is ob-'"*|7' vious that it muft be guarded againft. i. There may be jja^le to a fuperabundance of alkali prefent, or, which is the impuritief, fame thing, there may be mixed with the Pruflian teft a quantity of pure alkali ; or, 2. There may be contain- ed in it a quantity of yellow prufliat of iron, for which prufliat of potafs has alfo a confiderable affinity. If the Pruflian teft contain a fuperabundance of al- kali, two inconveniences follow. This fuperabundant quantity will precipitate thofe earthy falts which are li- able to contain an excefs of acid, and which are only foiuble by that excefs : Hence alumina and barytes will be precipitated. It is to the ufe of impure tefts of this kind that we owe the opinion, that barytes and alumina are precipitated by the Pruffian alkali, and the confequent theories of the metallic nature of thefe earths. This miilake was firft correfted, we believe, by Mr Kla- proth. Another inconvenience arifmg from the fuperabun- dance of alkali in the Pruflian teft is, that it gradually decompofes the blue prufliat which the teft contains, and converts ft into yellow prufliat. In what manner it does this will be underllood, after what has been faidi without any explanation. On the other hand, when the Pruffian alkali contain*- a quantity of ycllcw pruffiat of iron, as great inconve-^ niences follow. This yellow pruffiat has an affinity for pruffic acid, which, though inferior to that of the pot- afs, is ftiU confiderable ; and, on the other hand, the potafs has a ftronger affinity for every other acid than for the pruffic. When, therefore, the teft is expofed to the air, the carbonic acid, which the atmofphere al- ways contains, affifted by the affinity between the yel- low pruffiat and the pruffic acid, decompofes the pruf- fiat of potafs in the teft; and the yellow pruffiat is pre- cipitated in the form of Pruffian blue : And every other acid produces the fame eff^eft. A teft of this kind, therefore, would indicate the prefence of iron in every mixture which contains an acid (for a precipitation of Pruffian bltie would appear) ; and could not, therefore, be trufted to with any confidence. g,. We will not attempt to defcribe the various methods KUproth'*- which diff'erent chemifts have adopted of preparing this method of teft; but (hall fatisfy ouifelves with defcribing the fo^i^S ''■ method of Klaproth, which anfwers the purpofe com- pletely. This we ffiall do nearly in the words of Mr KIrwan. Prepare a pure potafs, by gradually proJeAing into a large crucible heated to whitnefs a mixture of equal parts of purified nitre and cryftals of tartar ; when the whole Part III. CHEMISTRY. IPiullbts. i. 494. f Bcrtbdht. Prudiat of ammoD'a and iron. 'J turn, de i'tyf- ixxiv. le:. is inje£>ed, let it be kept at a white heat for half an hour, to burn ofi the coal. Detacli the alkali thus obtained from the crucible, reduce it to poivdcr, I'prtad it on a muffle, and expofc it to a white heat for half an hour. DIflolve it in fix times its weight of water, and filter the fohition while warm. Pour this fulution into a glafs receiver, placed in a fand furnace, heated to 170" or 180'', and then gradu- ally add the beft Pruffian blue in powder, injedling new portions according as the former becomes grey, and iupplyiiig water as faft as it evaporates ; continue until the added portions are no longer dilcoloured, then iu- creafe the heat to 212° for half an hour. Filter the ley thus obtained, and faturate it with ful- phuric acid moderately diluted ; a precipitate will ap- pear ; when this ceafes, filter off the whole, and wafh the precipitate. Evaporate the filtered liquor to about one quarter, and fet it by to cryftallize : after a few days, ycllowifh cryftals of a cubic or quadrangular form will be found mixed with fome fulphat of potafs and oxide of iron ; pick out the yellowifh cryftals, lay them on blotting paper, and rediflblve them in four times their weight of cold water, to exclude the fulphat of potafs. 7. Effay a few drops of this folution with barytic water, to fee whether it contains any fulphuric acid, and add fome barytic water to the remainder if neceflary : filter off the folution from the fulphat of barytes, which will have precipitated, and fet it by to cryftallize for a few days ; that the barytes, if any (honld remain, may be precipitated. If the cryftals now obtained be of a pale yellow colour, and difcover no bluilh ftreaks when fprinkled over with muriatic acid, they are fit for ufe ; but if they ftill difcover bluilh or green ftreaks, the fo- lutions and cryftallizations muft be repeated. Thefe cryftals muft be kept in a well-ftopped bottle, which to preferve them from the air ihould be filled with alcohol, as they are infoluble in it. Before they are ufe(}< the quantity of iron they con- tain fhould be afcertained, by heating 100 grains to rednefs for half an hour in an open crucible : the pruf- fic acid will be confumed, and the iron will remain in the ftate of a reddiih brown magnetic oxide, which ihould be weighed and noted : This oxide is half the weight of the Prufiian blue afforded by the Prudian alkali ; its weight muft therefore be fubtrafted from that of me- tallic precipitates formed by this teft. Hence the weight of the cryftals, in a given quantity of the folution, (hould be noted, that the quantity employed in precipitation may be known. Care muft be taken to continue the cal- cination till the oxide of iron becomes brown ; for while it is black it weighs confiderably more than it (hould *. 9. Pruffiat of foda and iron. The only difcernible difference between this fait and the laft is, that it cry- ftallizes differently f. 10. Pruffiat of ammonia and iron. This triple fait has alfo been employed as a teft ; but it is not fo cafy to obtain it in a ftate of purity as the other two. It was difcovered by Macquer, and firft recommended by Mej'er. It forms flat hexangular cryftals, foluble in water, and deliquefces in the air. Heat decompofes it like the other pruffiats \. We ftall not give any defcription of the triple falls .1»7 formed by digeftinjj the alkalin; eurths on pruffiat of Sebst!.. iron; they are fufficiently knov.-n, and arc not of any '~~~v ■-' ufe except as tefts ; and in that ri-fpedt they are inferior to that above defcribed. They are all foluble in water, and are moft of them capable of cryftallizing. g;^ II. Pruffiat of mercury. This l'<»)t, which was firft I'rnflijt of formed by Schecle, is compofed of the piuffic acid'""'^"')'' combined with the red oxide of mercury. It may be formed by boiling ihc red oxide of mercury with Pruf- fian blue. It cryftallizes in tetrahtdral prifms, termi- nated by quadrangular pyramids, the fides of which cor- refpond with the angles of the prifm. This fait is capable of combining with fulphuric and muriatic acids, and forming triple falts, which have not yet been examined *. ' Serthtlhf Sect. XXIV. 846 Of Formats. The compounds into which the formic acid enters are cdM^i formats. We fliall nut r— » Metallic Solutions, Soluiioii 1)1 Hydrogenous Sul- phuret cf Poufs. Water impregnated with Sul- phuraieJ Hydrogen Gas. Hydrofulphuretof Fotafs. Oxide of antimony lublimed. Scarcely changes colour. Solution of oxide of arfenic. Sulphuret decompofed as by an acid. Becomes fomewhat muddy, and of a yellow colour. A yellow colour, but no pre- cipitate. Sulphat of titanium. A precipitate of a deep green. Molybdic acid. A brown precipitate. A brown precipitate. Chap. IV. 0/" Crystallization. 3«4 ery(la!s 8fiS The word cryjlal, in its ftrift and proper fenfe, fig- nifies a tranfparent body pofieiTed of a regular figure. But it is now ufed to denote a body which has affumed a regular figure whether it be tranfparent or not. Cry- Jiati'f^iMtion is the atl by which this regular figure is formed. As the greater number of cryftals belong to the clafs of neutral falts, it may not be improper, before we con- clude this part of the article, to make a few obfervations on the phenomena of cryftallization. As cryftallization is confeftedly nothing elfe than the regular arrangement of the particles of bodies, it is evi- dent that before it can take place the particles of the body to be cryftallized muft be at feme diftance from each other, and that they muft be at liberty to obey tiie laws of attraftion. They may be put into this fituation by three methods, folution, fufpenfion, and fufion. Farmed by '• Solution is the common method of cryftallizing fblution, falts. They are dilTolved in water : The water is flow- ly evaporated, the faline particles gradually approach each other, combine together, and form fmall cryftals ; which become conftantly larger by the addition of other particles till at lalt they fall by their gravity to the bot- tom of the vefTel. It ought to be remarked, however, that there are two kinds of folution, each of which pre- fents different phenomena of cryftallization. Some tails diffolve in very fmall pi'oportions in cold water, but are very foluble in hot water ; that is to fay, water at the common temperature has little effeft upon them, hut water combined with caloric diflblves them readily. When hot water faturated with any of thefe falts cools, it becomes incapable of holding them in folution : the oonfequcnce of which is, that the faline particles gra- duaUy approach each other and cryftalllze. Sulphat of foda is a fait of this kind. To cryftalllze fuch falts, nothing more is neceftary than to faturate hot ^water with them, and fet it by to cool. But were we to at- tempt to cryftalllze them by evaporating the hot water, we ftiould not fucceed ; nothing would be procured but a ftiapehf? mafs.- Many of the I'alts which follov; this law of cryftallization combine with a great deal of wa- ter ; or, which is the fame thing, many cryftals formed in this manner contain a great deal of water of cryftal- lization. There are other falts again which are nearly equally foluble In hot and cold water; common fait for inrtance. It is evident that fuch falts cannot be cryftallized by cooling ; but they cryftalllze very well by evaporating their folution while hot. Thefe falts generally contain but little water of cryftallization. 2. It appears, too, that fome fubftances are capable g„j-^._ of afturaing a cryftalline form merely by having their particles fufpended in water, without any regular folu.^ tlon ; at leaft it is not eafy, on any other fuppofition, to explain the cryftallizations of carbonat of lime foms- times depofited by waters that run over quantities of that mineral. ■I. There are many fubftances, however, neither fo- » j 7. , 1 1 • Li ri • r • 1 .• ■ , , And fu- luble in water, nor capable 01 being io mmutely divided f,oii. as to continue long fufpended in that fluid; and which, notwithftanding, are capable of afluming a cryftalline form. This is the cafe with the metals, with glafs, and fome other bodies. The method employed to crvftaJ. lize them \% fufion, which is a folution by means of ca- loric. By this method the particles are feparated from one another; and if the cooling goes on gradu^illy, they are at liberty to arrange themfelves in regular cryftals. There are many fubftances, howeirer, which it has been hitherto impoflible to reduce to a cryftalline form, either by thefe or any other method. Whether this be owing . to the nature of thefe bodies themfelves, or to our ig- norance of the laws by which cryftals are formed, as is ■ much more likely, cannot be determined. The phenomena of cryftallization feem to have at- ^ n ■,- r> ! I I- 1 r L • r 1 • , .1 CrvflaUl--' tratted but little or the attention ot the ancient philo- ztif'ion cr- - fophers. Their theory>indeed, that the elements of bb- plained. dies poflefs certain regular geometrical figures, m:iy have been fuggefted by thefe phenomena ; but we are ignorant of their having made any regular attempt to explain them. The fchoolmen afcribed the regular fi- gure of cryftals to their fubftantial forms, without orivlntr themfelves much trouble about explaining the meaning of the term. This notion was attacked by Boyle ; who proved th.at cryftak were formed by the mere aggrega- tion of particles *. But it ftlU remained to explain, . why that aggregation took pjace ? and why the parti- „,l"r)r^„- cles united in luch a manner as to form regular figures Jo/Tormjuri/ Thefe queitions were anfwered by Newton. Accord-^'"''''", ing to him, the aggregation is produced by the at- traction which he had proved to exift between the par- ticles of all bodies, and which afts as foon as tliefe particles are brought within a certain diftance cf each other by the evaporation of the liquid in v.-hich they are diffolved. The regularity of their figures he exp!aine, matter it is to proportion the diilerent ingredients w\Xh/i„„, dt abfolute exaftnefs, muft appear evident to all. CAira. xiv. Another circumttance which contributes much to va- '49- ry the form of cryftals, is the different degree of con- centration to which their folution has been reduced, and the rapidity or flownefs with which they are fonned. For it is too evident to require illuftration, that when cryftals are depofited very rapidly they muft obftruft one another, and mix together fo as very much to ob- fcure the natural regularity of their form. Even the nature of the veffel in which the cryftalliza- tion is performed is not without fome influence. But, independent of thefe accidental circumftances, p, 7* Mr Hauy has fhewn that every particular fpecies o^niyoioi cryftals has a primitive figure, and that the variations ftals. are owing to the different ways in which the particles arrange themfelves. Of this theory, which is certainly exceedingly ingenious, and even fatisfaftory, we fliall attempt to give a fhort view. Happening to take up a hexangular prifm of calca- reous fpar, or carbonat of lime, which had been detached from a group of the fame kind of cryftals, he obferved that a fmall portion of the cryftal was wanting, and that the frafture prefented a very fmooth lurface. Let abcde fgh (fig. 8.) be the cryftal; the frafture lay obliquely as the trapezium /I J u /, and made an angle of 135°, both with the remainder of the bale abcs ph and with tuef, the remainder of the fide i n ef. Obferving that the fegment ps u /in thuscut off had for its vertex in, one of the edges of the bafe abcnih of the prifm, he attempted to detach a Part. 111. CHEMISTRY. 393 Cryllalliza- a fimilar fepment in the n.irt to which the next edge may alfo be divided by fe£l'ons parallel to the fiiTcs of Cryflj|lu»- '■'""■ ^ c n belonged, employed for that purpol'e the blade of the primitive cryllal. It follows from this, that the , "°"" . * a knife, direfted in the fame degree of obliquity as the parts detached by means of thefe fedlions are finiilar, ' trapezium^ s u t, and afTifted by the ftrokes of a ham- and differ from one another only in fize, which dimini- mer. He could not fucceed : But upon making the flies in proportion to the length that the divjfion is car. attempt upon the next edge be, he detached another ried. But the divifion of the cryftals into fimiiar foljds fegmcnt, precifcly fimilar to the firft, and which had for has a term, beyond which we iTiOuld come to the fmblU its vertex the edge b c. He could produce no effeft on eft particles' of the body, which could not be divided the next edge a b ; but from the next following, a h, without chemical decompofition. It is probable, there- lie cut a fegment fimilar to the other two. The fixth fore, that the form of the integrant particles of a body edge likewife proved refraftory. He then went to the is the fame with the primitive form of its cryftals. Here other bafc of the prifm d efg h r, and found, that the then, we have a method of difcovering the form of the edges which admitted fedlions fimilar to the preceding particles of bodies ; and if this method could be applied ones were not the edges e f, d r, g k, correfponding vi'itli to all fubftances whatever, it would enable us to afcer- thofe which had been found divifible at the oppofite tain the af&nity of all bodies for each other by accurate bafe, but the intermediate edges d e, k r, gf. The tra- calculation. It muft be allowed that feveral objeftiong pezium I qy v reprefents the feftion of the fegment, might be made to the conclufions of Mr Hauy ; but his which had i r for its vertex. This feftion was evident- theory is, on the whole, fo plaufible, that it would cer- ly parallel to the feftion^ s u t ; and the other four fee- tainly be worth while to extend it, and rpply it to the tions were alfo parallel two and two. Thefe fcdions calculation of affinities as far as it is fufceptible of the were, without doubt, the natural joinings of the layers application. If the cryftals obtained by the above pro- of the cryftal. And he eafily fucceeded in making cefs be the primitive forms, it becomes a queftion of others parallel to them, without its being pofllble for fome confequence to determine in what manner the fe- him to divide the cryftal in any other direction. In condary forms are produced. this manner he detached layer after layer, approaching According to Hauy, all the parts fuperadded to the always nearer and nearer the axis of the prifm, till at primitive cryftals, in order to form the fecondaiy cry- " laft the bafes difappeared altogether, and the prifm was ftal, con fift of plates, which decreafe regularly by the converted into a iolid OX (fig. 9.), terminated by fubtraftion of one or more rows of integrant particles, twelve pentagons, parallel two and two ; of which in fuch a manner, that the number of thefe ranks, and thofe at the extremities, that is to fav, ASRIO, IG confequently the form of the fecondarv cryftal, may be EDO, BAODC at one end, and FKNPQ^MNPXU, determined by theory (c). ZQPXY at the other, were the refults of mechanical To explain this, let us fuppofe that EP (fig. 12.) re- divifion, and had their common vertices O, P fituated prefents a dodecahedron, terminated by equal and fimi- at the centre of the bales of the original prifm. The lar rhombs ; that this dodecahedron is a fecondary cry- fix lateral pentagons RSUXY, ZYRIG, &c. were the ftal, the primitive form of which is a cube : the fitua- remains of the fix fides of the original prifra. tion of this cube in the dodecahedron may be conceived By continuing feftions parallel to the former ones, from fig. 13. The fmaller diagonals DC, CG GF, the lateral pentagons diminilhed in length; and at laft FD, of four fides of the dodecahedron, united round the points R, G coinciding with the points Y, Z, the the fame folid angle L, form the fquare CDFG. Now points S, R with the points U, Y, &c. there remained there are fix folid angles, compofed of four plains, to- nothing of the lateral pentagons but the triangles YIZ, wit, the angles L, O, E, N, R, P (fig. 12.) ; and con- UXY, &c. (fig. 10.). By continuing the fame fee- fequently, by making feftions through the fmaller dia. tions, thefe triangles at laft difappeared, and the prifm gonals of the fides that form thefe angles, fix fquares was converted into the rhomboid a f (fig. ir.). will be made apparent, which are the fix fides of the So unexpefted a refult induced him to make the primitive cube, three of which are reprcfented in fig 13 fame attempt upon more of thefe cryftals ; and he found CDFG, ABCD, BCGH. that all of them could be reduced to fimilar rhomboids. This cube being compofed of cubic integrant parti- He found alfo, that the cryftals of other fubftances cles, each of the pyramids, LCDFG for inftance (fiir. could be reduced in the fame_ manner to certain prinii- 13.) which repofe upon its fides, muft alfo, accordin^j tive forms ; always the fame in the fame fubftances, but to the theory, be compofed of fimilar cubic ■jarticles. every fubftance having its own peculiar form. The To make this appear, let us fuppofe that ABFG (fig! primitive form of flnat lime, for inftance, was an oc- 14.) is a cube compofed of 72c; fmall cubes: Each of tahedron ; of fulphat of barytes, a prifm with rhomboi- its fides will confift of Si fquares, being the external dal bafes; of field-fpath, an oblique angled parallelopi- fides of as many cubic particles, which together con- ped, but not rhomboidal ; of adamantine fpar, a rhom- ftitute the cube. Upon ABCD, one of the fides of boid, fomevvhat acute; of blende, a dodecahedron, with this cube, let us apply a fqiiare lamina, compofed of rhomboidal fides ; and fo on. cubes equal to thofe of which the primitive cr'y'ftal con- Thefe muft be confidered as the real primitive forms fifts, but which has on each fide a row (.f cubes lefs of the cryftals; the other forms which they often af- than the outcrmoft layer of the primitive cube It will fume maybe c- the bafe of which is this face, and the vertex the cube r (fig. 18.). By continuing the fame operation on the other five fides of the cube, as many fimilar pyramids will be formed ; which will envelope the cube on every fide. It is evident, however, that the fides j)f thefe pyra- mids will not form continued planes, but that, owing to the gradual diminution of the lamina; of the cubes which compofe them, thefe fides will refemble the fteps of a ftair. We can fuppofe, however (what muft. certainly be the cafe), that the cubes of which the nucleus is formed are exceedingly fmall, almoll imperceptible ; that therefore a vaft number of laniiiis: are required to form the pyramids, and confequently that the channels which they form are imperceptible. Now DCBE (fig. 19.) being the pyramid relling upon the face ABCD (fig. 14.), and CBOG (fig. 19.) the pyramid applied to the next face BCGH (fig. 14.), if we confider that every thing is uniform from E to O (fig. 19.) in the manner in which the edges of the lamina of fuperpofit'wn (as the Abbe Hauy calls the lamiiix which compole the pyramids) mutually projed beyond each other, it will readily be conceived, that the face CEB of the firll pyramid ought to be exaftly in the fame plane with the face COB of the adjacent pyramid ; and that therefore the two faces together will form one rhomb ECOB. But all the fides of the fix pyramids amount to 24 tri- angles fimilar to CEB ; confequently they will form I2 rhombs, and the figure of the whole cryllal will be a do- decahedron, fimilar to that reprcfented in ng. 12 and 13. If the decreafe of the laminae of fuperpofition took phce according to a more rapid law, if each hmina had on its circumference two, three, or four rows of cubes lefs than the inferior lamina — in that cafe, the pyramids produced being lower, their adjacent faces ■K-ould no longer form one plane; and therefore the fur- face of the fecondary cryftal would confitl of 24 ifo- fceles triangles, all inclined towards each other. In this manner Mr Hauy has {hewn, that a variety of fecondary cryftals are formed, and that their forms vary by means of flight variations in the ratio of the decrement. Dodecahedral fulphurct of iron, for inftance, is formed from a cubic nucleus, by the addition of la- minx, decreafing, as in the example given above, with this difference, tliat from every lamina laid upon the face ABCD (fig. 14) only one row of cubes are fub- tracled at the fides AD and BC refpeftively ; whereas two rows are fubtrafted at each of the fides AB and CD. The confequence of this more rapid decrement on two parallel fides than on the other two will be, that the pyramid raifed on the face ABCD (fig. 14-), inftead of terminating in a fingle cube as in the ex.imple given above, will terminate in a range of cubes ; or (fwppofing the cubes infinitely fmall) inftead of termi- nating in a point, it will terminate in a ridge. The pyramid will therefore have for its two fides, contigu- ous to AB and DC, two trapeziums, and for its fides, ^ Part lir, contiguous to AD and BC, two triangles. Let usCryftalliza. fuppofe alfo, that with regard to the lamins of fuper- ^^_ pofition which arife on the face BCGH (fig. 14.), the decrements follow the fame law, and that each lamina decreafes by two rows of cubes towards the lines BC and HG, and only by one row towards the lines CG, BH : The pyramid, in that cafe, will be placed in a direction oppofite to the pyramid on ABCD, the ridge at the vertex of it running parallel to BC : the vertex of the pyramid raifed upon CDFG muft be parallel to CG: the pyramids on the three other fides of the cube ought to Hand each like that which arifes on the op- pofite face. The fides of all the fix pyramids thus formed amount to twelve trapeziums and twelve triangles. Every tri- angle is evidently contiguous and in the fame plane with a trapezium of the ntareft pyramid ; confequently the fecondary cryftal thus formed confifts of twelve fides, each of which is a pentagon. Several other examples have been given by Mr Hauy; but thefe are fufficieiit to (liew in what manner the va- rious fecondary forms of cryftals are conftrucled, ac- cording to the theory of that ingenious philofopher. In his refearches on this fubjeft, Mr Hauy percei- ved, that fome cryftals aflTumed fecondary forms which could not be accounted for by any decrement whatever along the edges. Thus, for inftance, fome bodies, the primary form of which is cubic, are fometimes found cryftallized in regular oftagons. Mr Hauy explains the formation of thefe fecondary cryftals, by fuppofing that the decrement took place parallel, not to the edges, but to the diagonals of the faces of the primary cubes. In order to comprehend this, let us fuppofe ABCD (fig. 20.) to be the furface of a lamina compofed of fmall cubes, the bafes of which are leprefentcd by the little fquares in the figure. It is evident, that the cubes a, h, f, d, e,f, g, h, i, are in the diredllon of the diago- nal of the fquare ABCD ; that the row of cubes y, v, i, u, x,y, c, is parallel to the diagonal ; as alfo the row n, t, I, VI, p, 0, r, s ; and that the whole figure might be divided into rows of fquares, each of which would be parallel either to the diagonal AC or DB. Now wc may conceive that the lair.ina; of fuperpo- fition, inftead of decreafing by rows of cubes parallel to the edges AB, AD, decreafe by rows parallel to the diagonals. Let it be propofed to conftruft around the cube AB GF (fig. 21.), confidcrcd as a nucleus, a fecondary fo- lid, in which the laminas of fuperpofition (hall decreafe on all fides by fingle rows of cubes, but in a direftion parallel to the diagonals. Let ABCD (fig. 22.), the fuperiur bafe of the nucleus, be divided into 81 Iquares, reprefeiiting the faces of the fmall cubes of which it is ciimpofed. Figure 23. reprefents the fuperior furface of the firft lamina of fuperpofition ; which muft be placed above ABCD (fig. 22.) in fuch a manner that the points a', V, c' , d', (fig. 23.) anfwer to the points a, b, Cy d, (fig. 22.). By this difpofition the fquares A a, 'Bb,Cc,'Dd (fig. 22.), which compofe the four outermoft rows of fquares parallel to the diagonals AC^ BD, remain uncovered. It is evident alfo, that the borders QV, ON, IL, GF (fig. 23.), projeA by one range beyond the borders AB, AD, CD, BC (fig. .22.), which is neceflary, that the nucleus may be en- veloped towards thefe edges ; For if this were not the cafe. Tart in. C H E M Cryftalti^a. cafe, re-entd !nj^ angles would be formed towards tlie tion. pa,.ts AB, BC, CD, DA, of the ciyllal; which angles » appear lo be excluded by the laws which determine the formation of fimplc crylUls, or, wliich comes to the fame thing, no fuch angles are ever oblervtd in any cry- ftal. The folid mull iucrcafe, then, in thofe parts to which th-' decrement does not extend. But as this de- crement is alone fufiicient to determine the form of the fecondary cryftal, we inay fet afide all the other varia- tions which intervene only in a fubfidiary manner, ex- cept when it is wilhed, as in the prefent cafe, to con- ftruft artificially a folid reprefentation of a cryftal, and to exhibit all the details which relate to its ftruftiire. The fnperior face of the fecond lamina will be A' G'L'K' (fiij. 24. )• It miift be placed fo that the points a", i",c", (^", correfpord to the pointsa 1/ c' d (fig. 23. j, •which will leave uncovered a iecond row of cubes at each angrle parallel to the diagonals AC and BD. The folid ftill increafes towards the fides. The large faces of the lamina: of fuperpofilion, which in fig. 23. were oftagoiis, in fig. 24. arrive at that ot a fquare ; and when they pafs that term they dccreafe on all fides ; fo that the next lamina has for its fupcvior face the {'unare B'M L'S' (fig. 25), lefs by one range in every diredlion than the preceding Umina (fig. 24.). This fquare muft be placed fo that the points e',f,g', //, (fig. 25.) correfpond to the points e,f,g, h (fig. 24.). Figures 26, 27, 28, and 29, reprefent the tour lamiiix which ought to rife fucceffively above the preceding ; the manner of placing them being pointed out by corre- fponding letters, as was done with refpeft to the three firll laminjE. The lafl lamina a' (fig. 30. ) is a fingle cube, which ought to be placed upon the fquare a (fig. 29.). The iaminx of fuperpofition, thus applied upon the fide ABCl) (fig. 22.), evidently produce four faces, which correfpond to the points A, B, C, D, and form a pyramid. Thefe facts, having been formed by Iaminx, which began by incrcafing, and afterwards decreaied, mufl be quadrilaterals of the figure reprefented in fig. 31. ; in which the inferior angle C is the fame point with the angle C of the nucleus (fig. 21. and 22.) ; and the diagonal LQ^reprefents L'G' of the lamina A'G'L'K' (fig. 24.). And as the number of Iaminx compofing the triangle L Q_C (fig. 31.) is much fmaller than that of the Iaminx forming the triangle ZLQ. it is evident that the latter triangle will have a much greater height than the former. The furface, then, of the fecondary cryftal thus pro- duced, muft evidently confift of 24 quadrilaterals (for pyramids are raifed on the other 5 fides of the primary cube exaftly in the fame manne"-), difpofed 3 and 3 around each folid angle of the nucleus. But in confe- quence of the decrement by one range, the three qua- drilaterals which belong to each folid angle, as C (fig. 21.) will be in the fame plane, and will form an equila- teral triangle ZIN (fig. 32.). The 24 quadrilaterals, then, will produce 8 equilateral triangles ; and confe- quently the fecondary cryftal will be a regular oftagon. This is the ftrufture of the oftahedral fulphuret of lead and of muriat of foda. Decrements which take place in this manner have been called by Mr Hauy decrements on the angles. There are certain cryftals in which the decrements on the angles do not take place in lines parallel to the diagonals, but parallel to lines fituated between the dia- 39." 1 S T R Y. gonals and the edges. This ik tl-.e cafe when the fub- Cryftalliza- tradfions are made by ranges of double, triple, &c. , "" "- moleculx. Fig. 33. exhibits an inftance of the ftib- '''" trattions in qucftion ; and it is feen that the mole- culx wliieh compofc the range reprefented by that fi- gure are aflorted in fuch a manner as if of two there were formed only one ; fo that we need only to con- ceive the cryftal compofed of parallelopipedons having their bafes equal to the fmall rectangles a I c d, e dfg, h g i I, &c. to reduce this cafe under that of the com- mon decrements on the angles. To this particular kind of decrement Mr Hauy has given the name of in~ iermediale. In other cryftals the decrements, either on the edges or on the angles, vary according to laws, the proportion of which cannot be expreffcd but by -the fraftion i. or \. It may happen, for example, that each himina ex- ceeds the following by two ranges parallel to the edges, and that it may at the fame time have an altitude triple that of a fimple molecule. Figure 34. rci)refents a ver- tical geometrical feftion of one of the kinds of pyramids which would refult from this decrement ; the effett of which may be readily conceived, by confidering that AB is a horizontal line taken on the uppei- bale of the nu- cleus, b a ^ r the feftion of the fufl lamina, of fuperpo- fition, gfen that of the fecond, &c. Thefe decrements Mr Hauy has called mixed. Thefe two laft fpccies of decreqients occur but rarely; Mr Hauy found them only in certain metallic fubflances. All the mctamorphofes to which cryftals are fubjttt- ed depend, according to Mr Hauy, on the laws of itrudure jult explained, and others of the like kind. Sometimes the decrements take place at the fame time on all the edges; as in the dodecah'-drou having rhom- bufes for its planes, as before mentioned ; 01 on all the angles, as in the odfahedron originating from a cube. Sometimes they take place only on certain edges or certain angles. Sometimes there is an uniformity be- tween them ; fo that it is one fingle law by one, two, three ranges, &c. which adls on the different edges, or the different angles. Sometimes the law varies from one edge to the other, or from one angle to the other; and this happens above all when the nucleus has not s fymmetrical form ; for example, when it is a parallelo- pipedon, the faces of which diflFer by their refpeftive inclinations, or by the meafure of their angles la certain cafes the decrements on the edges concur with the decrements on the angles to produce the fame cryftalline form, it happens alfo fometimes that the fame edge, or the fame angle, is fubjeded to feveral laws of decrement that fucceed each other. In ftiort, there are cafes where the fecondary cryftal has faces pa- rallel to thofe of the primitive form, and which combine with the faces produced by the decrements to modify the figure of the cryftal. The cryftals arifing from a fingle law of decrement have been called by Mr H&uy fimple fecondary forms ; tbofe which arife from feveral fimultaneous laws of de- crement he has called compound fecondar^^ forms. " If amidft this diverfity of laws (he obferves), fome- times infulated, fometimes united by combinations more or lefs complex, the number of the ranges fubtradled were itfelf extremely variable ; for example, were thefe decrements by twelve, twenty, thirty, or forty ranges» or more, as might abfolutely be poflible, the multitude Dd 3 of 396 tr)nali;: CHEMISTRY. Part Iir, a of the forms which might exift in each kiiiJ of mineral would be immeiifc, and exceed what could be imagined. "" Bat the power which elTccts the fubt raft ions fecms to have a very limited aftiun. Thefe fubtractions, for the moil part, take place by one or two ranges of molecules. 1 have found none which exceeded four ranges; except in a variety of calcareous fpar, forming part of the col- leftionof C. Gillet Laumoiit, the ftrufture of which de- pends on a decrement by fix ranges ; fo th.it if there exift laws which exceed the decrements by foar ranges, there is reafon to believe that they rarely take place in nature. Yet, notwithilanding thefe narrow limits by which the laws of cryftallization are circunifcribed, I have found, by confining myfelf to two of the fimplcll laws, that is to fay, thole which produce fiibtraftions by one or two ranges, that calcareous fpar is fiifceptible of two thou- fand aud forty-four different forms: a number which exceeds more than fifty times that of the forms already known ; and if we admit into the combination decre- ments by three and four ranges, calculation will give 8,388,604 poflible forms in regard to the fame fubftance. This number may be dill very much augmented in con- fequence 01 decrements either mixed or intermediary. " The itriae remarked on the furface of a multitude of cryftals afford a new proof in favour of theory, as they always have direilions parallel to the projecting edges of the laminae of fuperpofition, which mutually go beyond each other, unlefs they arife from fome par- ticular want of regularity. Not that the inequalities refulting from the decrements muft be always fenfible, fuppofing the form of the cryftals had always that degree of finifhing of which it is fufceptlble; for, on account of the extreme minutenefs of the molecules, the furface would appear of a beautiful polifh, and the flriae would elude our fenfcs. There are therefore fccondary cry- ftals where they are not at all obferved, while they are very vifible in other cryftals of the fame nature and form. In the latter cafe, the aftion of the caufes •which produce cryftallization not having fully enjoyed all the conditions neceffary for perfefting that fo deli- cate operation of nature, there have been ftarts and in- terruptions in their progrefs, fo that, the law of conti- nuity not having been cxaftly obferved, there have re- mained on the furface of the cryftal vacancies apparent to our eyes. Thefe fmall deviations are attended with this advantage, that they point out the direction accord- ing to which the ftris are arranged in lines on the perteft forms where they efcape our organs, and thus contri- bute to unfold to us the real mechanifm of the ftrutlure. " The fmall vacuities which the edges of the lamlnse of fuperpofition leave on the furface of even the moft per- fect fecondary cryftals, by their re-entering and falient angles, thus afford a fatisfaftory folution of the difficul- ty a little before mentioned ; which is, that the frag- ments obtained by divifion, the external fides of which form part of the faces of the fecondary cryftal, are not like thofe drawn from the interior part. For this di- veiCty, which is only apparent, arifes from the fides in queftion being compoftd of a multitude of fmall planes, really inclined to one another, but which, on account of their fmallnefs, prefent the appearance of one plane ; fo that if the divifion could reach its utmoft bounds, all thefe fragments would be refolved into mole- cules fimilar to each other, and to thofc fituated to- wards the centre. " The fecundity of the laws on which the variations Ciyftalliza. of cryftalline forms depend, is not confined to the ''""• producing of a multitude of very different forms with " » "* the fame molecules. It otten happens alfo, that mole- cules of different figures arrange themlelves in fuch a manner as gives rife to like polyhcdra in different kinds of minerals. Thus tlie dodecahedron with rhombufes for its planes, which we obtained by combining cubic molecules, exifts in the granite with a ftrufture com- pofed of fmall tetrahedra, having ifofceles triangular faces ; and I have found it in fparry fluor (fiuat of lime), where there is alfo an affemblage of tetrahedra, but regular ; that is to fay, the faces of which are equi- lateral triangles. Nay more, it is poflible that finiilar molecules may produce the fame cryftalline form by dif- ferent laws of decrement. In fhort, calculation has condufted me to another refult, which appeared to me ftill mo*'e remarkable, which is, that, in conlequcnce of a fimple law of decrement, there may exill a cryftal which externally has a perfeft refemblance to the nu- cleus, that is to fay, to a fohd that does not arife from any law of decrement *." * Ann. de Cbint. xvii.- SucH Is a fhort view of the theory by which Mr**^* Hauy explains the various cryftalline forms of the fame fubftance. We would with pleafure have entered more into detail, had not moft of his examples been deduced from fubftances which belong rather to mi- neralogy than to the elements of chcniiftry. Thij theory, to fay no more of it, is, in point of ingenuity, inferior to few ; and the mathematical flciU and iuduftry of its author are intitled to the greateft applaule. But what we confider as the moft important part of that philofopher's labours, is the method which they point out of difcovering the figure of the integrant particles of cryftals; becaufe it may pave the way for calculating the affinities of bodies, which is certainly by far the moft important part of chemiftry. This part of the fuDJeft, therefore, deferves to be inveftigated with the greateft care. Mr Hauy has found, that the primitive form of all the cryftals which lie has examined may be reduced to fix; I. The parallelopipedon in general, comprehending the cube, the rhomboid, and all lolids terminated by fijc fides parallel two and two; 2. Tlie regular tetrahedron ; ^. The oftahedron with triangular fides ; 4. The hex- agCTUil prifm ; 5. The dodecahedron bounded by rhombs ; 6. The dodecahedron bounded by ifofceles triangles. Were we to fuppofe that thefe primitive forms are exaftly fimilar to the form of the integrant particles which compofe them, it would follow, that the, integrant •particles of all the cryftals hitherto formed have only fix different forms. This fuppofition, how- ever, is not probable ; becaufe the fame nucleus has been difcovered in different fpecies of minerals, and be- caufe we can eafily conceive integrant particles of diffe- rent forms, combining in fuch a manner as to compofe nuclei of the fame figure, juft as we have feen that dif- ferent primitive forms are capable of producing the fame fecondary form. Still, therefore, in endeavouring todifco- ver the integrant particlea of bodies, there are difficulties to remove, which hitherto, at leaft, have been unfurmount- able. But the theory of Mr Hauy may be confidered as a firft ftep towards the difcovery ; and Sijiep in refearches. of fo difficult a nature is of very great confequence. We Partlir. C H E M I Con.lufion. We have now fini'died the three firft parts of this av- '—"y' — ' tide, which comprehend all the elementary part ot ehe- miftry. We ought now to proceed to the fourth part, which was to confift of a chemical examination of luh- ilances as tliey exift in nature in the mineral, vegetable, and animal kingdoms; but this, for various reafons, we fhall defer till we come to the words Mineralogy, and Animal and Vegetable Subst/inces. We fliall finifli this article with a few remarks upon the chemical nomenclature, which for fome time pafl has been an objeft of ferious attention. Chemiftry was unfortunately firft cultivated by a fet of ignorant men, filled with the higheft notions of their own importance, and buoyed up with the mighty feats iner,c!ature.^^,j,j^i, ^jigy ^^yg to perform by their art. The little which they did know they were anxious to conceal; and their anxiety was no lefs to infpire the vorld with high ideas of their knowledge and power. The confequence of this was, that they loaded chemiftry with the moll ri- diculous and whimfical names that can well be conceived. Liver of fulphur, mercury of Ife, horned moon, butler of antimony, the double fecret, the corraline fecrct, the fecret of vitriol, the wonderful fait, the fecret fall, the fait tviih many -virtues, the fill of two ingredients, the foliated earth 873 Remarks on the che niciil no- S T R y. ' 397 1 . livery fubftance ought to have a nsme, and not to Condufion. be denoted by a phrafc. »— y— j 2. Names ought to be as much as pofiible conformable to the nature of the things lignified by them. 3. When the character ot a fubftance is not well enough known to determine the denomination, a name which has no meaning is preferable to one which con- veys a falie idea. 4. In the choice of new words thofe ought to be pre- ferred which have their roots in the dead languages moft generally known, that the word may be eafily fug- - gefted by the ftnfe, and the fenfe by tlie word. 5. The new words ought to be as fuitablc as poflible to the genius of the languages for which they are formed. This nomenclature was approved of by Macquer, and by Bergman, who had himfclf propofed one upon a plan not very different (d). He wrote to Morveau, and ex- . horted him to profecute his undertaking with courage. " Do not fpare (fays he) a fingle improper denomina- tion ; thofe that are already learned will be always fo, and thofe that are not will learn the fooner*." mr .7-', ' 1 his norrienclature was adopted by leveral chemiits, ci;„, p^,,^ and it was ufed in the greateft part of the firft volume face, of the chemical part of the Encyclopedic Melhodique ; ef tartar, were the names by which they diftinguilhed but the new difcoveries in chemiftry had produced a fome of the moft familiar preparations; and, were it more accurate method of reafoning, and had enabled ■worth while, a great many more names of the fame ftamp might eafily be added. As foon as chemiftry had attrafted the attention of men of fclence, the abfurdity of its nomenclature was felt, and feveral partial improvements were at different times made in it. Macquer, iii particular, difcardcd many of the ancient names, and fubftituted others leis exceptionable iu their place. But foon after the publication of the fii ft edition of his Dlftlonary, an evil began to be felt feverely, which never could have occurred to the earlier cliemifts. Hi- therto the number of objefls which had engaged the attention of thofe who cultivated the fcience had been very limited ; the acids amounted only to five, the earths to four, the metals to i 2 or 14, and the neutral falts Icarcclv exceeded 20 or ^o. To remember names for fo fmall a number of bodies, however ridiculous they happened tolae, was no very difficult matter. But about that time, In confequence chiefly of the difcovery of fixed air by Dr Black, which laid the foundation of pneumatic chemiftry, the fcience began to extend itfelf, and to enlarge its boundaries with inconceivable rapi- dity. The number of bodies connetted with it, and which it had to defcrlbe, foon became immenfe; and if every one of them received names not dependant upon one another, the moil retentive memory could not have remembered the thoufandth part of them. The difliculty of ftudying chemiftry from that tinn« till the year 1782 muft have been very great : it was even perceived and complained of by the matters of t?he fcience. In 1782 Mr de Morveau, who had undertaken the chemical part ot the Encyclopcdie Methodiqite, pub- liftied in the journal de Phyfique a new chemical no- menclature, and at the fame time invited all thofe per- fons who were fond of chemiftry, and intercfted in its proprefs, to propofe objeftions and improvements. This new nomenclature was formed agreeable to the five following rules :. Lavoifier to explain the phenomena of the fcience without the alFirtance of the hypothetical principle of phlogifton, which had hitherto been neceflary. As the language, even in its improved ftate, was accommodated to this principle, and prefuppofcd Its exiilence, new changes became evidently neceftary, in order that, ac- cording to Morveau's rule, the words might denote tlie moft eifentlal properties- of the things intended to be fignified.. Accordingly, when Morveau was in Paiis in 1787, Lavoifier, BerthoUet, and Fourcroy, agreed to labour in concert with him to bring the chemical no- menclature ftill nearer to perfeftlon. ' Thele pliilofo- phers, aflifted by the mathematicians of the Royal Aca- demy and by feveral chemilfs, formed a new nomencla- ture, which they made public in 1787. For fome time little attention v/as paid to this no- menclature by ii»reigu chcmills, and it feemed generally to be dilapproved. The adherents of the phlogiitic fyftem in France, who were exceedingly numerous, viewed it as aji engine artfully formed to undermine and deftroy their favourite theory. They relolved, there-* fore, unanlmoufly, to crufti, it pofiible, this new inftru. ment, which they confidered as in nnfiros fibricata machlna muros, ■ InfpeSura domos, •uailiiraqtie defuper urbi. And for this purpofe they exerted themfelves with a vf- gour, which was only equalled by tho zeal and indefati- gable exertions of their antagonills.- A kind of civil war was thus kindled in the republic of letters, which was carried on with great animofity : And poilcrity ' will fee, with regret, m.cji of undoubted genius at times divefting themfelves of the armour of truth and of can- dour, and endeavouring, to lerve their party, and ftab their adverfaries with darts fteeped in the poifon of ca- lumny and falfehood *. This conteft, however, which ( gee thg was not confined to France, was produftive of good ei-Jouni.dc fctts, which infinitely furpafted all. the bad ones. It^hf-^"^' 90. 91. fa/' occa- (o) See his thoughts on a natural hiftory of foflils ia the 4th vol. of his Opufc, 398 Concrufuni. * Confide r a iions on the doSrine of pblogiflon , Introduc- tion. C H E M I occafioned an actrumulation of fnfts, produced a rigid examination of theories and opinions, introduced an ac- curacy into chemical experin>ents which has been of the moft eflential fervice, and gave tliat tone and vigour to the cultivators of chcniillry wliich have brought to light the moft fubhme and unlooked for truths. It deferves attention, and the faft is no inconfiderable evidence in favour of the antiphlogilHc theory, that ahvioft all the ilhiftrious chcmifts who at prefent adhere to it declared origir.alK agaiiift it. .Berthollet, Morveaii, Black, Kir- wan, and many other chemifts who are now its ableft defenders, were at firft its moft powerful opponents. •' This fyftem had hardly been publillied in France (favs Dr Prieftley, who ftill continues to adhere to the doctrine of phlogifton) before the principal philofophers and chemifts of England, notwithftanding the rivalftiip which has long fubfifted between the two countries, ea- gerly adopted it. Dr Black in Edinburgh, and as far as I hear all the Scots, have declared themfelves con- verts, and, what is more, the fame has been done by Mr Kirvvan, who wrote a pretty large treatifc in oppofitiun to it. The Englifti reviewers of books, I perceive, uni- verfally favour the new doftrine. In America, alfo, I hear of nothing tlfc. It is taught, 1 believe, in all the fchools on this continent, and the old fyftem is entirely €,xploded. And now that Dr Crawford is dead, I hardly know of any perfon except my friends of the Lunar Society at Birmingham, who adhere to the doc- trine of phlogifton ; and what may now be the cafe with them in this age of revolutions, philofophical as well as civil, I will not at this diftance anfwer for. " It is no doubt thne, and of courfe opportunity of examination and difcuflion, that gives ftability to any principles. But this new theory has not only kept its ground, but has been conftantly and uniformly advan- cing in reputation more than ten years, which, as the at- tention of fo many perfons, the beft judges of every thing relating to the fubjeft, has been unreniittingly given to it, is no inconfiderable period. Every year of the laft twenty or thirty has been of more importance to fcience, and efpecially to chemiftry, than any ten in the preceding century *." We have endeavoured in the preceding article to ftate the different theiKies which have fucceffively made their appearance in chemijli-y with as much fairnefs as poffible. If we have fucceeded, the reader will be enabled to judge for himfelf which of thefe theories is the moft con- fiftent with truth ; or rather, if we have fucceeded, he will join with us in thinking that the theory of Lavoi- fier is in moft points an accurate account of what takes place in nature. This we confider as a fufficient reafon for having adopted the new nomenclature ; for, as Morveau long ago obferved, moft of the objedions that were made to it were rather levelled at the doftrine of thofe who formed it, than at the nomenclature itfelf. Its fu- periority to every other nomenclature cannot be dif- put«d for an inftant ; and the vaft facility which it has S T R Y. Part III, added to the acquifition of chemiftry, niuft be acknow-Coiiclufton, ledged by every one who knows any thing about the « "* fcience. The Table of the new nomenclature will not be expefted here, as it has been already given in tho Appendix to the article Chemistry 'in X.\m Encyclo' ped'ta. At any rate, it would have been unnecelTary, as we have ufed the new names all along; and therefore our readers muft by this time be well acquainted with them. Upon the almoft infinite number of criticifms vihich have been made on the new nomenclature, and the ma- ny new terms which fince its publication have been fuc- ceffively propofed, we do not mean to enter. Few of thefe terms can bear a comparifon with the French no- menclature, and ftill fewer have any claim to be pre- ferred to it ; and the philofophers who perfift in thefe uielefs innovations, are more probably actuated by the dcihe of appearing to have a Qiare in the great revolu- tion which chemiftry has undergone, tlian by any hopes of being able to improve the accuracy or the elegance of its language. How few have difplayed the magna- nimity of an illuftrious pl'iilofophtr of our own country, who, though he had invented a new nomenclature him. felf, exhorted his pupils not to ufe it, but to adopt that of the French chemifts, which was likely foon to come into univerfal ufe. Even the etymological remarks which have been made on the new nomenclature, we confider as either of little confequence or as ill-founded. The philofophers who formed it have difplayed a lagacity and a moderation which could not be excelled, and have, upon the whole, formed a language much more fyftematic, and much more perfeft, tlian could have been expefted; and who- ever compares it with the nomenclature propofed in 1782 by Morveau, will fee how great a (hare of it is due to that illuftrious philofopher. Notwithftanding what we have here faid, we would not be undeiftood to confider the new nomenclature as already arrived at a ftate of fuch abfolute perieflion, that no alteration whatever can be made in it except for the worfe. Such pertettion belongs not to the works of man ; nor if it did, could it be expefted in this cale, if we confider for a moment the prefent ftate of chemiftry. New difcoveries muft occafion additions and alterations in the nomenclature ; but the authors of the new nomen- clature have given u« the rules by which changes and additions are to be made ; and if they are adhered tO) we may expeft with confidence that the language of chemiftry will in its advancement to perfedlion keep pace with the fcience. We have in the preceding ar- ticle ventured in an inftance or two to adopt little im- provements that have been fuggefted by later writers. We have taken the liberty, too, of choofing, from the variety which the BritKh chemifts have propoied, that mode of fpelling each of the terms which appeared to us moft agreeable to the Englifli idiom, and moft con- formable to analogy : Whether or not we have made a proper choice muft be left for others to determine. INDEX rKE>as-rin-. FtATt .ttv-ui _Viu,.8. (•ii!"..sns'ntY i't..viK.->cix . Kii";. 10. Vij.-.i:i S — n 1 n 1 1 ; 1 1 J 1 -;» Wtr.l l'i,ir.-Art. F.g.18 A, ''- 3 A V\;<::i:i- «- 1 1 '•^ i ?- /■ c ^■ r / c/ ■J' < nt e t ti /f y rt j- ^ .^ .1 /• A -f z ^ /' » c I I I I M I J I" 2- I I f - I I I I I I I I Ic rf-H — "T n _^ TZ — ^ ^- — / ' «^ ll.nii). tt- .r,sr:i-!. Vi^--l3 l"iV;J+. , ^ ■/ , *■ , Vi-tr-a. ■■ . , . H 1 - • J ,F Ri'-' ' f ! 1 ! ' ' • H_ ^ Tig.'G. l-.^o2 . / - n .18. , I. 1 1 .\ / ' u V.V.&l- T^ il^J+ . L-L Index. CHEMISTRY. 399 INDEX. JCETATS, n" »co. -^ Jcttitci, 464, and Part III. chap, if fed. \ i. Jcetic acid, Part II. chap. v. lea. 12. jtcetous acid, Part II. chap. v. feft. II. Acid principle, ;488. yldd,i:id\,'in fulphuric acid, 398. in nitric acid, 41 2. /ic'td foaps, Part III. chap 1. feft. 2. jlc'tds, Part 11. chap. v. Adds, animal, 549. metallic, 559. vegetable, 526. Ac'idum pingue, 374. ./f note. Alumen, n° dl^i- Alumina, Part I. ch. iv. feft. 6. acetite of, 784. benzcat of, 821. borat of, 749. camphorat of, 829. carbonat of, 775. citrat of, 814. fluat of, 765. laftat of, 817. muriat of, 705. nitrat of, 676. oxalat of, 805. phofphat of, 73?. faccholat of, 818. Alumina, febat of, n" 847, foap of, 594. fuberat of, 836. fulphat of, 627. fulpl\ite of, 665. tartrite of, 8n. Amalgam, what, 93. Amber, qo2. Ammonia, Part II. ch. iv. feft. 3. acetite of, 779. anrat of, S49. brnzoat of, 820. borat of, 725. camphorat of, 825. carbonat of, 770, citrat of, 813. cuprat of, 852. fluat of, 761. lat^at of, 817. malat of, 816. mercurial of, 851. muriat of, 697. nitrat of, 670. oxalat of, 804. phofphat of, 730. prufiiat of, 837. faccholat of, 8iS. febat of, 8ji6. foap of, 591. fuberat of, 832. fulphat of, 627. fulphite of, 66 r. tartrite of, 8 1 o. zincat of, 855. Animal zcids, 549. Antimony, Partl. ch.iii. feft. 10. acetite of, 794. benzoat of, 822. muriat of, 7 16. nitrat of, 687. oxalat of, 806. febat of, 848. fulphat of, 650. tartrite of, 812. Anliphlogijlic theory, p. 277. note. ylnt.t, acid of. Part II. ch. v. feft. 29. Apulum, n" 240. Aquafortis, 407. Aqua-regia, p. 224, note. Arcanum duplicatum, n° 624. tartari, 777. Arfeniats, 552, and Part III. ch. ii. feft. 26. Arfenic, Part I. ch. iii. feft, 12. acid, 550. acetite of, 795. benzoat of, 822, Arfenic, borat of, n" 7 j8. fluat of, 767. muriat of, 717. nitrat of, 688. oxilat of, 806. phofphat of, 740. febat of, 848. fulphat of, 651. tartrite of, 81 2. Atmofpheric air, compofition of, Aurum mufivuni, 1 20. Aujlrum, 240. A-zot, Part I. ch. ii. feft. 9. how combined with oxy- gen, 421. B Balfam of fulphur, 370. Balm of Peru, foap of, 609. ■ Barytes, Part I. ch. iv. feft. 3. acetite of, 780. •borat of, 725. camphorat of, 826. carbonat, 771. citrat of, 814. fluat of, 762. laftat of, 817. malat of, 816. muriat o.^, 699. nitrat of, 671. oxalat of, 805. oxymuviat of, 724. phofphat of, 731. pruffiat of, 838. faccholat of, 818. foap of, 595. fuberat of, 834. fulphat of, 62S. fulphite of, 661. Barytic, water, 209. Beer, when firll known, 340. Bill metal, 122. Benzoats, 501, and Part III. ch. ii. feft. 1 9. Benzoic acid, Part II, ch. v. feft. 20. Benzoin, 499. foap of, 608. Bergman, charafter of, 1 7 4. Bifmuth, Part I. ch. iii. feft. i i. acetite of, 793. benzoat of, 822. borat of, 757. muriat of, 7 1 5. nitrat of, 686. oxalat of, 806. fulphat of, 649. tartrite of, 812. Black, Dr, difcovers latent heat, 268. difcovers the compo- fition of the carbo* nats, 200, 373. Black bodies fooneft. lieated by light, 325. lead, 109. Blende, p. 247, note. Blue liquid, n° 513. Boiling point of water, experi- ments on, ^37, 338. Bologna ftone, 629. Bomhyc acid, 546. Boracic acid. Part II. ch. v. feft. 8. Borats, 447, and Part II. ch. ii. feft. 8. Borax, 441, 744. Barbonium, 240. Brap, 140. Brittlenefs, to what owing, 303* Bronze, 122. Brunfviick green, 81 2. c Cadmea, J 34. Careous acid, 457. Calchanlum, 641. Calcination, 6 1. Calomel, 718, 725. Caloric, Part I. ch. v. whether a fubftance, 241,312. equilibrium of, 246. of fluidity, 269. of evaporation, 270. methods of obtaining, 292. whether the fame with light, 328. Calorimeter, 265. Calx, 6 1 . Camphor, 506. Camphorats, 5 10, and Part III. ch. ii. feft. 21. Camphoric acid. Part. II, ch. v, feft. 22. Canton' i pyrophorus, 320. Capacity for caloric explained, 362. Carbon, Part I. ch. ii. feft. 3. attempts to decompofe, 44. Carbonats, 462, and Part III. ch. ii. feft. 10. Carbonated hydrogen gas, 42,- and Part III. ch. iii. Carbonated azotic gas, 50. Carionie 400 'Curbon'ic acid, 32, and Part II, ch. V. fcift. 10. Carbunets, 11° 35. Curiunct of iron, I 39. muiigaiictc, 175. ■/.[lie, 139. Cavallo's expcrimcnts'on light, 34i- Ca.'uendijh, Henry, difcovers the coiiipofitioa of wa- ter, :;4 I . and of nitric acid, 409. Caujltcum acidum, 374. Cemfnlalion, 1 13, Chalybeated tartar, 8 1 2. Charcoal, condufting power of, 252- Chemtjlry, definition of, I. Chronic acid. Part 11. ch. v. feci. 35. Chromum, 189, Cinnabar, 91. Cilrats, 478, and Part III, ch. ii. feft. 14. Citric acid, 476. Cobalt, Part I. ch. iii. fe£l. 13. acetite of, 790. benzoat of, 822. borat of, 752. fluat of, 767. muriat of, 7 10. nitrat of, 680. oxaht of, 806. foap of, 598. fulphat of, 646. Cohejion, 570. Cold, methodofproducing, 280. why produced by mix- tures, 282. Colour efFefls the heating of bodies by hght, 335. Colouring matter of Pruflian bhie, v33. Combujlion explained, 293. Common falts, 696. Compound affinity, 583. Compound bodies, Part II. Condenfation dirainifhes fpecific caloric, 303. Condu8ing powers of bodies, 251, 2:^6. CoiilaB, no abfolute, 568. Copper, Part I. ch. iii. fed. j. acetite of, 792. ■benzoat of, 822, borat of, 756. citrat of, 815. fluat of, 767. muriat of, 7 1 4. nitrat of, 685. oxalat of, 8c6. febat of, S48. foap of, 602. lulphat of, 684. CHEMISTRY. Corh, n" 5ri. Corroftve muriat of mercury, 72?. fublimate, 7JJ. Corundum, 2*0- Crawford, Dr, hia experiments on fpecific caloric, 264. his theory of com- bultion, 297. Cryjlal, rock, 216. CryJlallf:.ation, Part III. ch. iv. Cryjlals, what, 18, 864. Cuprum, when firft. ufed, page 239, note. D Decrepitation explained, p. 359, notes. De Luc's theory of light, 332. Denjity, incr^fafed by hammer- ing, of different mixtures of acidsand water, 397, 41 1, 424. Dephlrjgijlicated air, 6. muriatic acid, 428. Detonation of nitre, 667. Diamond, 38. Dige/li've fait of Sylvius, 777. Difpoftng affinity, 584. Diuretic fait, 777. DuaUity, 60. E Earthi, Part I. ch. iv. properties of, 192. combinations with each other, 205, 217. 225. remarks on, J40. EJfer-vefcence, what, page 214, note. Efflorefcing explained, n° 626, and note. Eggs hatched by eleftricity, Ekilrive attraftion, what, J 3. Ekaricity, analogy between and caloric, 246. whether an agent in producing heat by friftion, 3.14. Emetic tartar, 812. Empyreal air, 6. Epfom fait, 633. Equilibrium of caloric, 246. Ether, 355. Ethiops mineral, 90. Eudiometer, 420. Euler's theory of light, 3 1 5. Expanjion of bodies, table of, 242. Extraa of Saturn, 790. F Fat, acid of, 543. Fea'hers, why a warm cover. ing, n° 260. Febrifuge fait of Sylvius, 695. Fire damp, 36. Fixed air, 203, 457. ammonia, 701. oil, 361. Fluats, 455. and Part III. ch. ii. kct. 9, Fluids, whether conduiftors of caloric, 256. provedthattheyare, 259. Fluor, 449. Fluoric acid, Part II. ch. v. feft. 9. Formic acid, 529, Formica rufa, 539. Franklin's experiments on the heating of bodies by light, Friaion, caloric produced by, 307, 310- Fulminating gold, 849,! filver, 850. Furs, in what their warmth con- fifts, 260. Fufible fpar, 449, Fujion, 867. G Gallats, 498, and Part III. ch, ii. feft. 18. Gallic acid, Part II. ch. v. fed. 19. Galls, 493. Gas explained, 5, 457, Gafeous form of bodies, to what owing, 279. Gafes, not heated red hot, 327. Glaf, o,-ii. condudlingpowerof, 253. of antimony, 145. Glauber's fait, 626. Glucina, 236, 237. Gold, Part I. ch. iii. feft. r. afted on by nitric acid, 413- . fulminating, 848. acetite of, 79S. benzoat of, 822. febat of, 848. foap of, 605. ftannat of, 853. Guaic, foap of, 6ic. Gunpo'wder, 667. Gypfum, 630. Hnrtfhorn, 382. i/juy's theory of cry ftallization, 872. Heat, Part I. ch. v. makes bodies luminous, 326. Hepatic gas, 40. Hot bodies lighter than cold, 248. i Index. Houi poun, n" 441 . Hutton'i theory of light, 333. explanation of the ap- parent refle£lion of cold, page 283, note. Hydrogen gas. Part I. cli. ii, lea. 4. Hydrogenous fulphurets, 858. Hydrofulphurets, Part III. ch, iii. I yames's powder, 742, "^l Jargon, 243. _ " Jargonia, Pait I. ch. iv. feft, 7. & page 363, note, acetite of, n" 785. muriat of, 706. nitrat of, 677. fulphat of, 640, ^^'y 335- liiflammahk air, page 2 1 7, Iron, Part I. ch. iii, feft. 6., call, 113. cold fhort, 108, wrought, I II, acetite of, 786, benzoat of, 822. borat of, 750. carbonat of, 776. citrat of, 815, fluat of, 767. green fulphat of, 64 1» laftat of, 817. malat of, 816. muriat of, 707. nitrat of, 678, oxalat of, 806, phofphat of, 736, prufliiat of, 839. red fulphat of, 642. febat of, 848. foap of, 601. fulphite of, 666. tartrite of, 812. Irvine, Dr, his theory of heat, 296. theorem to difcover the real zeno, 272. K Kirwan's theory of phlogifton, 299. experiments en the flrength of acids, 497,511, L Lae, white y 1 7. Laccic acid. Part II. ch. v, feftj 24. LaBats, 486, and Part III, ch. ii. feft. 16. Z«fl(Vacid.PartII.ch.v.feft,l7. Lana philofophica, page, 238. note. Latent caloric, n° 269. Lavoifier and La Plage, experi. ments ments of on fpecific caloric, n« 265. Lead, Part I. ch. ili. fed. 8. acetite of, 782. benzoat of, 822. borat of, 754. fluat of, 767. muriat of, 712. nitrat of, 683. oxalat of, 806. febat of, 8^8. foap of, 603. fulphat of, 647. Lemons, cffential f;ilt of, 802. Light, Part I. ch. vi. * Ligneous acid, page 333, note. L Lime, Part I. ch. iv. fed. i . acetite of, 781. benzoat of, 821. borat of, 746. camphorat of, 827. citrat of, 814. fluat of, 763. laftat of, 817. malat of, 816. niercuriat of, 851. inuriat of, 701. nitrat of, 672. oxalat ot, 805. oxy- muriat of, 724. phofphat of, 732. plunibat of, 854. priifliat of, 83S. faccholat of, 8 1 8. febat of, 847. foap of, 59Z. fuberat of, 834. fulphat of, 630. fulphite of, 663. tartiite of, 8n. Lime-water, 195. Liquid blue, 5 13. Liquor filicum, 21 5, 377. Lute, what, 7. M Macquer'i opinion about phlo- gifton, 296. Mdgne/ia, Part I. ch. iv. fed. 2. acetite of, 783. benzoat of, 8ji. borat of, 748. camj)horat of, 8 28. citrat of, 814. fluat of, 764. laftat of, «I7. malat of, 8 1 6. muriat of, 703. nitrat of, 674. oxalat of, 805. oxy-muriat of, 724. phofphat of, 734. prufliat of, 838. faccholat of, 818. febat of, 847. SuppL. Vol. I. Part II. CH E M I Magnejtii, foap of, n° 593. fuberat of, 835. fulphat of, 633. fulphite of, 604. tartrite of, 811. Malats, 483, and Part III. ch. ii. fed. 15. Malic acid, 480. Miilleability, 59. Manganefe, Part I. ch. iii. fe£l. 15- benzoat of, 822. fluat of, 767. muriat of, 709. nitr:it of, 680. oxalat of, 8c6. phofphat of, 738. ioap of, 606. fulphat of, 644. Marcaftte of gold, 134. Marks given to metals by the ancients, 1 30. Marine acid, 422. MaJfKoi, 125. Menachanite, 186. Mephetic acid, 457. Mercury, Part I. ch. iii. feft. 4. a nonconduftor of ca- loric, 259. acetite of, 796. benzoat of, 822. citrat of, 815. fluat of, 767. hydrogenous fulphu- ret of, 859. muriat of, 7 ) 8. nitrat of, 689. oxalat of, 806. oxy-muriat of, 7 2 J. prufliat of, 845. febat of, 848. foap of, 596. tartrite of, 8 1 2. white fulphat of, 651. yellow fulphat of,653. Metallic acids, 559. Metals, Part I. ch. iii. expanfion of, 242. condutling power of, 254. Miafmata, how deftroyed, 426. Microcofmic fait, 730. yi//nf/-(!/ cryftal, 667. Minium, 1 25. Mi poun, 441. Mify, 641. Molybdena, 180. Molybdenum, Part I. ch. iii. fedl. 17- Molybdats, ^^^. Molybdic acid, ^^^, Mother ley, explained, page 25 r, note. ■ Muriatic acid, Part II. ch. v. fea. 5, S T R Y. Muriatic acid dcpliloglfticated, n" 428. oxygenated, 428. compofition of, 434- Murials, 425, and Part III. ch. ii. feft. j. N Names given to metals by the ancients, 130. Narcotic fait, 442. Newton's theory of light, 315. Niciel, Part I. cli. iii fed. 14. acetite of, 789. borat of, 753. fluat of, 767. muriat of, 711. nitrat of, 682. oxalat of, 806. phofphat of, 739. foap of, 599. fulphat of, 645. Nitrats, 414, and Part III. ch. ii. feft. 3. Nitre, 667. ads on platinum, p. 312, note, cubic, 669. Nitric acid, 51, and Part II. ch ii. fed. 3. its ad Ion on oils, 413. Nitrites, 417, and Part III. ch. ii. fed. 4. Nitrous air or gas, 409, 418. acid. Part II. ch, v. fed. 4. Nitro-muriatic acid, 43 1. Nitrum fixum, 624. flammans, 670. femivolatile, 670. O Oil of vitriol, 391. Oils, Part II. ch. iii. drying, 365. noncondudois of heat, 295- Olive, when firft cultivated in Europe, 330. Olive oil analyfed, 363. Orichalcum, what, 140. Orpiment, 155. Ouretic acid, 729. Oxalats, 470, and Part III. ch. ii. fed. 12. Oxalic acid, Part II. ch. v. fed. Oxide and oxydation, 68. Oxides of antimony, 144. arfenic, 154. bifmuth, 149. cobalt, 160. copper, 96. gold, 71. iron, 10 J. lead, 125. 3E 401 Oxides of manganefe, n" 173. mercury, 85. molybdenum, 181. nickel, 167. platinum, 81. filver, 74. tellurium, 188. tin, I 19. titanium, i8y. tungllen, 179. uranium, 183. zinc, 136. metallic, remarks on, 191. Oxygen, Part I. ch. i. gas contains light, 322. caloric it gives out, 278. Oxy-muriats, 432, and Part III. ch. ii. fed. 6. Oxy muriatic acid, Part II. ch. V. fed. 6. P Panacea holfatica, 624. Pe-la, page 33 z, note. PercuJJion produces heat, and why, n° 302. Perlaled fait, 729. acid, 729. Peiuter, 14c, 152. Phlogijlon explained, 29J, 20, its exiftcnce difpro- ved, 301. Pblogi/llc theory, page 277, note. Phlugijlicated air, n° 52. Phofphats 438, and Part III. ch. Ii. fed. 7. Phojphorated hydrogen gas, 41. azotic gas, 50. Phofphoric acid, 28, and Part II. ch. v. fed. 7. Phofphorous acid, 440. Phofphorus, Part I. ch. ii. fed. 2. whether an ingre- dient of fl:eel, 1 15. Phofphuret of antimony, 145. arfenic, 156. bifmuth, 151. cobalt, 162. copper, 100. gold, 72. iron, 108. lead, 127. lime, 197. manganefe, 174. mercury, 92. molybdenum, 181. nickel, 169. platinum, 82. potafs, 375. lilver, 76. tin, 121. Phofphuret 402 Phofphuret of tungften, no 179. zinc, 138. PiSet's experiments on light and caloric, 325, and p. 284, note. P'mchleck, 140. Pin poun, 44 1. Plajcr of Paris, 631. Platinum, Part I. ch. iii. fedl. 3. benzoat of, 82i. oxalat of, 8c6. febat of, 848. Plumbago, 109. Pneumatic apparatus, 7. Pomphohx, page 240, note. Potafs, Part II. ch. iv. feft. I. acetite of, 777. acidulous oxalat of, 802. antimoniat of, 856. benzoat of, 820. borat of, 74^. camphorat ot, 823. carbonat of, 768. citrat of, 813. fluat of, 759. laftatof, 817. malat of, 816. muriat of, 605. nitrat of, 667. oxalat of, 801. oxy-muriat of, 722. phofphat of, 728. prufliat of, 837. iaccholat of, 818. febat of, 846. fuberat of, 830. fulphat of, 624. fulphite of, 659. tartrite of, 808. Pounxa, 441- Precipitate per fe, 88. Priejikyi theory of combuftion, 297. experiments on ni- nitrous gas, 409. Prince's metal, 140. Prujian blue, 530, 839. alkali, 532, 841. Prujiats, 537. PruJJic acid, Part II. ch. v. La. 28. affinities of, 840. Pyrolignites, 524. Pyrolignous acid. Part II. ch. v. feft. 26. Pyromucites, 522. Pyromucous acid, Part II. ch. v. feft. 25. Pyrophori, 32"!. Pyrophorus of Romberg, 639. Pyrotartrites, 528. Pyrotartarous acid, Part II, ch. V. feft. 27. ^icklime, 193. C H E M I ^idjilver, Part I. ch. iii. fedl. 4- R Rancidity, n° 364. Realgar, I 55. Red he.Ti.t. explained, 326. lead ore of Siberia, page 299, note, precipitate, n« 88. Redu^icn explained, page 232, note. Regenerated tartar, n° 777. Rejtduum, what, 19. Refin explained, p. 299, note. Rock cryftal, 2 1 6. Rujl of iron, lO?. S Saccharine acid, 467. Saccholats, 492, and Part III. ch. ii. feft. 17. Sal ammoniac, 697. catharticus amarus, 633. de duobus, 624. gem, 696. mirabile, 626. perlatum, 629. polycrefl Glaferi, 624. Salt of Saturn, 790. Salli, 622. neutral, 623. Saturation explained, 571. Scammony, foap of, 611. Scheele, account of, 33 1, and note in page 286. Sea fait, 696. Sebats, 545, and Part III. ch. ii. fedf. 25. Secret foliated earth of tartar, 777- , . ^ fal ammoniac, 027. Selenite, 63O. Semimetals, 69. Seydler fait, 633. Siderum, 108. Sidneia, 239. Silica, Part I. ch. iv. feft. 5. Scheele's theory of the formation of, 4J0. fluat of, 766. Sill-, why a warm covering, 260. ^ Silkworm contains an acid, 546. Silver, Part I. ch. in. feft. 2. fulminating, 850. acetite of, 797. benzoat of, 822. muriat of, 720. nitrat of, 691. oxalat of, 806. ,fuap of, 604. fulphat of, 6jJ. Simple affinity, 582. bodies what, 3. Smoiing liquor of Libavius, 726. S T R Y. ijnow of antimony, 144. Soap, 378._ origin of the term, 586. method of forming, 587. hard, ^86. foft, 59;. of wool, 590. of filli, 590. Soaps, Part III. ch. i. Soda, Part II. ch. iv. fed. 2. acetite of, 778. benzoat of, 820. borat of, 744. , camphorat of, 824. carbonat of, 769. citrat of, 813. fluat of, 760. ladat of, 817. malat of, 816. muriat of, 696. nitrat of, 669. oxalat of, 80J. oxy-muriat of, 723. phofphat of, 729. prufliat of, 837. faccholat of, 8 1 8. febat of, 848. fuberat of, 831. fulphat of, 626. fulphite of, 660. Solulle tartar, 808. Solution, 865. why haftened by heat, 291. Sory, 641. Sparks produced by the colli- fion of quartz, 305. Specific caloric, what, 262, 290. table of, 267. Specificum purgans, 624. Spelter, 134. Spirit of Mindererus, 779. nitre, 407. fait, 422. Stahl's theory of combuftion, 295- Steam, 336. a nonconduftor of calo- ric, 261. Steel, 112. Stibium of the ancients, what, 142. 5/o««,condufting power of,255. Strength of acids, 397, 411. Stronlites, Part I. ch. iv. feft. 4. acetite of, 782. carbonat of, 773. muriat of, 702. nitrat of, 673. oxalat of, 805. phofphat of, 733. fulphat of, 633. tartrite of, 811. Suberats, 514. and Part III. ch. ii. feft. 2 2. Index* Suberic acid, Part II. ch. v. iett. 23. Succinats, n^ 50J. Succinic acid, Part II. ch. 5, ' feft. 21. Sugar, 465. acid of, 466. of bifmuth, 793. of lead, 790. of milk, 488. of Saturn, 790. Sulphats, 399. and Part III. ch. ii. feft. 1. Sulphites, 405. and Part III. ch. ii. feft. 2. Sulphur, Part I. ch. ii. feft. i. Sulphurated hydrogen gas, 40, 857. Sulphuret of ammonia, 386. antimony, 145. arfenic, 155. barytes, 2 10. bifmuth, 150. cobalt, 161. copper, 99. iron, 107. lead, 126. lime, 196. magnefia, 204. mercury, 90, 9r, 859. molybdenum, 181, nickel, 168. potafs, 375. filver, 7j. tellurium, 188. tin, 120. tungften, 179. uranium, 183. zinc, 137. Sulphurets, remarks on, 858. Sulphuric acid. Part II. ch. v. feft. I. Sulphurous acid. Part II. ch. v. feft. 2. Syl-vanile, page 247, note. Syrupous acid, page 333, note. T Tanning principle, page 327, n. Tartar, 472, 807. emetic, 812. Tartarized tinfture of Mars^ 812. iron, 8 I 2. Tarlarous acid, Part II. ch. v. feft. 14. Tartrites, 474. and Part III. ch. ii. feft. 13. Telluriumr Part I. ch. iii. feft. 20. fulphat of, 658. Temperature explained, 290. Tennant, Smithfon, decompofes carbonic acid, 459. Tenjton of caloric explained, 247. Terra Index. Trrra penderofa, 207. Thermometer, 244. how a meafure of temperature, 248. ftands higher when its bulb is black- ened, 325. finks in an ex- hauftedreceiver, Wedgewood's, 224. Tm, Part ch. iii. feft. 7. acetiie of, 791. benzoat of, 822. borat of, 755. fluat of, 767. niuriat of, 713. nitrat of, 684. oxalat of, 806. oxy-muriat of, 726. febat of, 848. foap of, 600. fulphat of, 647. fin/oil, n8. finplate, n° 128- C H E M I S T R Y. Vitriolated ammonh, 627. tartar, 624. Vitriolic acid, 391. Volatile and •volatilical'ion, what, Tincat.'^nr. Titanium, Part I. ch. iii. led.. 19. muriat of, 721. fulphat of, 6j7. Tombac, white, 157. Tungstats, 5; 54. Tungsten, Part I. ch. iii. fed. 16. Tung Stic acid. 553. Turbitli mineral, 653. Turpentine, foap of, 607. Types, printers, compofition of, 147. U Vegetable acids, 5 26. Venus, cryftals of, 792. Verdigrife, 792. Vermilion, 91. Vinegar, Part II. ch. v. feft. 1 1. of Saturn, 790. Vital air, 6. Vitriol, blue, 648. green, 641. white, 643. ^/VWo/ of potafs, p. 359, note, mother water of, 642. '7- Volatile alkali, 382. oils, 369. Uranium, Part I. ch. iii. fedl. £8. acetite of, 799. jihofphat of, 741. fulphat of, 655. W Water, 38, Part II. ch. i. weight of, 334. hillory of its decompo- (Ition, 341. proofs of its decompo- fition, 342. a nonconduftor of heat, 256. of nitre, 407. Watery fufion explained, 626, and note. Wedgeiuood, Thomas, his expe- riments on light, 325, }yi(i> 327.329- /rf(7^fwo(»(/'s thermometer, 224- Wikklcs'i experiments on fpeci- fie caloric, 263. Wine, effential fait of, 777. ^W.condudling power of,252. Y Tttria, 2»8. Z Zero, real attempt to difcover, 271. Zinc, Part I. ch. in. fedl. 9. acetite of, 787. benzoat of, 822. borat of, 750. carboHat of, 776. fluat of, 767. laftat of, 817. malat of, 816. muriat of, 708. ■• nitrat of, 679. oxalat of, 8c6. phofphat of, 737. ioap of, 597. fulphat of, 643. tartrite of, 81 2. Zirconia, page 363, note. Zoonic acid, 547. C tt E Cherubim. CHERUBIM were emblematical figures ; of which « an account, a very vague one indeed, has been given in the Encyclopedia Britannica. We are far from think- ing ourfelves qualified to improve that account, or to explain emblems in the Jewifh worthip, which even Jo- fephus did not underftand ; and we certainly (hould not have refumed the fubjeft but to gratify a numerous clafs of our readers, and to comply with the requeft of fome highly refptfted friends. The followers of Mr Hutchinfon, who are firmly per- fuaded that their mafter brought to light from the writings of the Old Teftament many important doc- trines which had lain concealed from all the piety, all the induRry, and all the learning of 1700 years, be- lieve that, among other things, he and they have been able to afcertain the form and the import of the He- brew Cherubim. Their difcoveries on this fubjedt, as we have been loid by better judges than we pretend to be, are more clearly ftated by Mr Parkhuril in his He- brew Lexicon, than by any other writer of that fchool. We (hall therefore lay before our readers his doftrine refpefting the form of the artificial cherubs, as well as of their emblematical meaning ; arid fubjoin a few re- marks, which the nature of his realoning has forced from us. " Firjl, then, as to ihe form of the artificial cherubs in the tabernacle and temple. Mofes (fays our author) was commanded (Exod. xxv. 18, 19.) ' Thou fhalt make two cherubs : of beaten gold flialt thou make them at the two ends of the mercy-ftat. And thou CHE (halt make one cherub at the one end, and the other Cherubin: cherub at the other end : msan )o, out of the mercy- ' •''—'- feat (Margin Eng. Traflat. of the matter of the mer- cy-feat) fhall ye make the cherubs at the two ends thereof.' All which was accordingly performed (Exod. xxxvii, 7, 8.), and thefe cherubs were with the ark pla- ced in the holy of holies of the tabernacle (Exod. xxvi. 33, 34. xl. 20.) ; as thofe made by Solomon were af. terwardc in the holy of holies of the temple (i Kings vii. 23, 27.) We may obferve that in Exodus Jehovah fpeaks to Mofes of tire cherubs as of figures well known ; and no wonder fince they had always been among believers in the holy tabernacle from the beginning. (See Gen. iii. 24. Wifd. ix. 8. And though mention is made of their faces (Exod. xxv. 20. 2 Chron. iii. 13.), and of their wings, (Exod. xxv. 20. I Kings viii. 7. 2 Chron. iii, II, 12.); yet neither in Exodus, Kings, nor Chro- nicies, have we any particular defcription of their form. This is however very exaftly, and, as it were, anxioufly fupplicd by the prophet Ezekicl, ch. i. 5. ' Out of the midll thereof ( ;'. e. of tiie fire infolding itfelf, ver. 4.) nioT the likenefs of four livings creatures or animals ; ninS Q1N mo-r the likenefs of a man (being) with them.' This lall Hebrew exprefiion cannot mean that thev, t. e, the four animals, had the likenefs of a man, which interpretation would indeed make the prophet con- tradict himfelf (comp. ver. 10.) ; but it imports that the likenefs of a man in glory, called (verfe 26.) aiH PX1D3 mm the likenefs as the appearance of a man, 3 E 2 and CHE [ 404 ] CHE Cherabim. and particularly defcribed in that and the following piece of gold as that was' (Exod, xxv. 18, 19. xxxvii. Cl.cmbi'm, ^~~^''~~^ verfcs, waswitli them. Ver. 6. ' And there were four p.). Now the mercy-feat, made of gold and crowned, v~-- faces to one (nwT or fimilitude), and four wings to one, was an emblem of the Divinity of Chrift (See Rom. ili. on'? to thi'm. So there were at lead two compound fi- 25. The cherubs therefore reprefented not the ange- gures. Ver. lo- ' And the likenefs of their faces; the lie, but the Divine nature. face of a man, and the face of a lion, on the right fide, " ^'Uy, The typical blood of Chrift was fprinkled to them four ; and the face of an ox to them four ; and before tlieni on the great day of atonement (compare the face of an eagle to them four.' Ezekiel knew (ch. Exod. xxxvii. 9. Lev. xvi. 14. Heb. ix. 7, 12.) : And X. I. 20.) that thefe were cherubs. Ver. 2i. ' Four this cannot in any fenfe be referred to created angels, faces inub to one (cherub) and four wings to one.' but mud be referred to Jehovah only ; becanfe. This text alfo proves that the prophet faw more cherubs " t^thly. The liigh priell's entering into the holy of than one, and that each had four faces and four wings, holies on that day, reprefented Chrill's entering with And we may be certain that the cherubs placed in the his own blood into heaven ' to appear in the prefence holy of holies were of the form here defcribed by the of God for us' (Heb. ix. 7, 24.) And, pried and prophet of Ezekiel, becaufe we have already 5'''6'' When God ' raifed Chrid (the humanity) feen from Exodus, t Kings, and z Chronicles, that from the dead, he fet him at his own right hand in the they likewife had faces and wings, and becaufe Ezekiel heavenly places, far above, 'TnEPANn, all principality knew what he faw to be cherubs, and becaufe there and power, and might and dominion, and every name were no four faced cherubs any where elfe but in the that is named, not only in this world, but alfo in that holy of holies; for it is plain from a comparifon of which is to come (Eph. i. 21.). Angels and antho- Exod. xxvi. I, 31. I Kino-s vi. 29, 32. and 2 Ciiron. rities and powers being made fubjeft unto him' (l Peter iii. 14. with Ezekiel xli. 18, ig, 20. that the artiiicial iii. 22.) cherubs on the curtains and vail of the tabernacle, and " bthly. The prophet Ezekiel faith (ch. x. 20.), on the walls, doors, and vail of the temple, had only ' This is the living creature, n'nn (which mud mean tv/o faces ; namely, thofe of a lion and of a man. one compound figure, comp. ver. 14.) that .\- faw' nnn " For it mud be obferved further, that, as the word indead of, a fubditute of ' the Aleim of Ifrael. nnn, ana is ufed for one compound figure with four faces, it is granted, may refer either to fituation or fubditu- and D'm3 in the plural for feveral fuch compounds (fee tion, (fee Gen. xxx. 2. 1. 19.) as the fenfe requires. Exod. xxv. 18, 19. xxxvii. 8. I Kings vi. 23 — 26 ), Here, notwilhilanding what is faid ver. 19. the latter fo is 3113 applied to one of the cherubic animals, as to fenfe is preferable ; becaufe it was the glory of the God the ox, Ezek. x. 14.; (compare ch. i. 10.) to the of Ifrael, i. e. the God-man in glory, (compare ch. i. coupled cherub, or lion-man, Ezek. xli. 18. ; and D'^tis 26.) not the Aleim (the Trinity) of Ifrael that were to feveral of the cherubic animals, as to feveral oxen, 1 over the cherubim ; and the text fays not, tlvfi were Kings vii. 36. (compare ver. 29.) to feveral coupled the living creatures, but, this was the living creature, cherubs, Exod. xxvi. I. I Kings vi. 32, 35 & al. I which I faw ''n-'ii" 'rhK nnn.' Now the glory was over proceed to fhew. both the cherubims, ver. 19. but one compound cherub " Seconefly, of wliat the cherubs were emblems, and only was a fubditute of the Aleim. with what propriety. " If 't dionld be here afted, Wh)'' then were there " That the cherubic figures were emblems or repre- two compound cherubs in the holy of holies ? I anfwer, fentatives of fomething beyond themfelves is, I think, Had there not in this place been two compound che- agreed by all, both Jews and Chridians. But the quef- rubs, it would have been naturally impoflible for them tion is, Of what they were emblematical ? To which I to reprefent what was there defigned ; for otherwife, anfvver in a word, Thofe in the holy of holies were em- all the faces could not have looked inwards toward each blematical of the ever-blefled Trinity in covenant to re- other, and down upon the mercy-feat, and on the inter- deem man, by uniting the human nature to the Second ceding high pried fprinkling the typical blood of Chrid, Perfon; which union was fignitied by the luiion of the (fee Exod. xxy.vii. y.) and at the lame time have look- faces of the lion and of the man in the cherubic exhi- ed outward toward the temple, rraS (Vulg. ad domum bition, Ezek. i. 10. compare Ezek. xli. 18, 19. The exteriorum, to the outer houfe.) 2 Chron. iii. 13. Or, cherubs in the holy of holies were certainly intended to in other words, the Divine Perfons could not have been reprefent fome beings in heaven, becaufe St Paul has reprefented as witnefllng to each other's voluntary en- expreisly and infallibly determined that the holy of ho- gagements for man's redemption, as beholding the la- Ijes was a figure or type of heaven, even of that heaven critice of Chrid's death, typified in the Jewifli church, where is the' peculiar refidence of God (Heb. ix. 24.). and at the fame time as extending their gracious re- And therefore thefe cherubs reprefented either the ever gards to the whole world. _ (See Ifa. liv. 5. and Spear- blefTed Trinity with the man taken into the elfence, or man's Inquiry, p. 382. edit. Edinburgh, created fpiritual angels. The following reafons will, I " The coupled cherub, or lion-roan, on the vail and hope, clearly prove them to be emblematical of the curtains of the outer tabernacle, and on the vail, doors, former, not of the latter : and walls of the temple, accompanied with the emble- " I/?, Not of angels ; becaufe (not now to infift on matic palm-tree, is fuch a ftriking emblem of the lion of other ci'rcumftances in the cherubic form) no tolerable the tribe of Judah (Rev. v. 5.) united to the man reafon can be afllgned why angels diould be exhibited Chrift Jefus, as is eafy to be perceived, but hard to be with four faces apiece. evaded. Thefe coupled cherubs appropriate the taber- " 2il/y, Becaufe the cherubs in the holy of holies of nacle or temple, and their vails, as emblems of Chrift, the tabernacle were, by Jehovah's order, ' made out of and exprefs in vifible fymbols what he and his apoftles the matter of the raercy-feat, or beaten out of the fame do in words. See John ii. 19, 21. Heb. viii. 2. ix. 1 1. X. 20. I CUE [ Clxru'iim. X. 20. comp. Matt, xxvii. ^i. And as the texts _ ' " \i • cited from the New Tellunient afford us divine antliori- ty for afTertiiig that the outer tabernacle or temple was a type of the body of Chrilt, fo they fiirnilli us with an irrefragable argument to prove that the cherubs on their curtains or walls could not rcprcfent angels. For did angels dwell in Chrill's body ? No, furely ; But • in him dwelt all the fulnefs of the Godhead bodily.' (Col. ii.,9.) "I gO on to confider the propriety of the animals in the cherubic exhibition reprefenting tht Three Perfons in the ever-blcfled I'rinity. And here to obviate any undue prejudice which may have been conceived againlt the Divine Perfons being iymbolicallv rcprefented under any animal forms wtiatever, let it be remarked that Je- hovah appeared as three men to Aliraliam (Gen. xviii. ); that the ferpent of brafs fct up by God's conjmand in the wildcrnefs was a type or emblem of Chrift, God- man, lifted up oil the crofs (comp. Num. xxxi. i — 9. with John iii. 14, 15.); that at Jcfus's baptifm the Ho- ly Spirit dcfcended in a bodily (hape, like a dove, upon him (Luke iii. 21, 22.); that Chriil, as above intima- ted, is exprefsly called the lion of the tribe of Judah (Rev. V. 5.) ; and continually in that fymbolical book fet before us under the fimilitude of a lamb. All thefe are plain fcriptural reprefentations, each of them admi- rably fuited, as the attentive reader will eafdy obferve, to the particular circumftances or fpecific defign of the exhibition. Why then fhonld it appear a thing incre- dible, yea why not highly probable, that Jehovah Aleim fhould, under the typical ilate, order his own Perfons and the union of the manhood with the efTence to be reprefented by animal forms in the cherubim of glory ? Efpecially if it be confidei-ed that the three animal forms, exclufive of the man (who flood for the very human nature itfelf) are the chief of their refpeftive genera : the ox or bull of the tame or graminivorous ; the lion, of the wild or carnivorous ; and the eagle, of the winged kind. — But this is by no means all : For as the great agents in nature, which carry on all its operations, certainly are the fluid of the heavens, or, in other words, the fire at the orb of the fun, the light if- fuing from it, and the fpirit or grofs air conllantly fup- porting, and concurring to the aiifions and effedls of the other two ; fo we are told (Pfal. xix. i.) that a"'3U'n 'rx Tias a'lEco the heavens (are) the means of declaring, recounting, or particularly exhibiting the glory of God, even his eternal power and godhead, as St Paul fpeaks, Rom. i. 2D. And accordingly Jehovah himfelf is fome- times, though rarely (1 prefume for fear of millakes) called by the very name n'ow or X'W heavens in the Old 'J'eflament, fee 2 Chron. xxxii. 20. (comp. 2 Kings xix. 14. Ifa. xxxvii. 15.) Dan. iv. 23. or 26.; as he is more frequently expreffed by On^an^ heaven in the New. (See Mat. xxi. 25. Mark xi. 30. 31. Luke xv. 18, 21. xx. 4, 5. John iii. 27.) Yea not only fo, but we find in the Scriptures both of the Old and New Teftament, that the Perfons of the eternal Three and their econo-' uft Mai c Luk i. H E IV. 2. or III. 20. J-,uk 1. 78. ii. 32. Jchn i. 4 — 9 viii. 12. xii. ^5, 36, 46.) The Third Perfou has no - other diftinctivc name in fcripture but """ in Hebrew, and nvjuM-' in Greek (both which words in their pri- mary fenle denote the material fpirit or air in motion), to which appellation the epithet '■'"'P. "J-i" holy, or one of the names of God, i^ ufually added : and the aftions of the Holy Spirit in the fpiritual fyftem are defcribed by thofe of he air in the natural (See John iii. 8. xx. 22. AiTts ii. 2.) Thus, then, the fecond and Third Per- fons ot the ever blelTcd Triiiity are plainly reprefented in fcripture by the material light and air. But it is further written, Jehovah thy Aleim is a confuming fire. Dcut. iv. 24. (Comp. Deut. ix. 23. Heb. xii. 29. Pfal. xxi. ic. Ixxviii. 21. Nah. i. 2.) And by fire, dtTivtrd either immediately or mediately from heaven, were the typical facrifites confumed under the old dif- penfation. Since, then, Jehovah is in fcripture repre- fented by the maleiial heavens, and even called by their name, and efpecially b) that of fire, and fince the Se- cond and Third Perfons are exhibited refpeftively by the two conditions of light and fpirit, and fince fire is really a condition of the heavenly fluid as much diftindl from the other two as they are from each other, it re- mains that the peculiar einblem of the Firfl Perfon (as we ufually fpeak) of the eternal Trinity, confidered with refpeft to the other two, be th^ fire. " Bearing then in mind that tlie perfonality in Jeho- vah is in fcripture reprefented by the material Trinity of nature ; which alio, like their divine antitype, are of one fubftance, that the primary fcriptural type of the Father is fire; of the Word, light ; and of the Holy Ghoft, fpirit, or air in motion ; we lliall eafilv perceive, the propriety of tl'.e cherubic emblems. For the ox or bull, on account of his horns, the curling hair on his forehead, and his unrelenting fury when provo- ked (fee Pfal. xxii. 13.) is a very proper animal em- blem of fire ; as the lion from his ufual tawny gold- like colour, his flowing mane, his fhining eyes, his great vigilancy and prodigious ftrength, is of light; and thus likewife the eagle is of the fpirit or air in aiitlon, from his being chief among fowls, from his impetuous 100- tion (ice 2 Sam. i. 25. Job ix. 26. Jer. iv. 13. Lam. iv. 19.), and from his towering and furpriling flights in the air (fee Job xxxix. 27. Prov. xxiii. ;. xxx. 19. Ifa. xl. 31. and Bochart, vol. iii. p. 173.) And the heathen ufed thefe emblematic animals, or the like, fometimes feparate, fom'etimes joined, in various manueis, as repre- fentatives of the material Trinity of nature, which they adored. Thefe particulars Mr Hutchinfon has pro- ved with a variety of ufeful learning, vol. -rnrp. 381, et feq. and any perfon who is tolerably acquainted with the heathen mytiiology will be able to iiicrcafe his va- luable colledfluu with many inflances of the fame kind from modern as well as ancient accounts of the pagan religions., " Thus, then, the faces of the ox, the lion, and the eagle, reprefenting at fecond hand the Three Perfons Cherubim. mical operations in the fpiritual, are reprefented by the of Jehovah, the Father, the Word, and the Holy Spi- three conditions of the celeftial fluid and their opera, rit ; and the union of the divine light with man beins tions in the material world. Thus the peculiar emblem plainly pointed out by the union of the faces of the of the Word or Second Perfon is the vDiy or light, and lion and the man (fee Ezek. i. 10. xll. 18.), we may he is and does that to the fouls or fpirits of men which fafely affert, that the cherubim of glory (Heb. ix. c.) the material or natural light is and does to their bo- in the holy of holies were divinely inftituted and proper dies. (See inter al. 2 Sam. xxiii, 4. Ifa. xlix. 6. Ix. i. emblems of the Three Eternal Perfons in covenant to redeem CHE 'frheru' im. rcJcciTi man, and of the union of tlie divine and human ' ' 'f~~ nalut-es in the perfon of Chrifl. And we find (Gen. iii. 24 ) that immediately on Adam's expidfion from ]);iiadii'c, and the cefTatioD of the firft u\- paiadifiacal d fpenfation of rchgion, Jehovah Alcim hmilclt let up tbiTe emblom-;, together with the burning flame nssnron niliing upon itfelf, to keep the way to the tree of life; undoubtedly, coiifidering the ferv ices performed before them, iK>t to hinder, but to enable, man to pafs through it." I'hus far Mr Parkhurft; and to his difTertation where is the man who will deny the merit of erudition, com- bined with ingenuity ? To the latter part of his rea- foning, however, objeftions obtrude themfelvcs upon us of fuch force, that we know not how to anfvver them. The reader obferves, that, according to this account, the cherubim are only it fecofid hand emblematical of the 'Holy Trinity, and that the primary emblem is that fluid which the author conceives to lill the folar fyftem, and to be one fubllance under the different appearances or nioditications oijire, light, and grofs air. But unfortu- nately for this reafoning, we are as certain as we can be of any matter of fa6t, that Jire anti air are not one lubftance ; that the grofi air itfelf is compounded of very different fubifances ; and that even light is a diffe- lent fublfance from that which caufes in us the fenfa- ticn of heat, and to which modern chemifts have given the name of fa/or/'i,- (See C hem isTRY-/n(/fx in this Sup- plement). We admit, that the primary atoms of all matter nw^ be fubitances of the very fame kind, though ■we do not certainly knoiu that they are: but this makes nothing for our author's hypothefis ; becaufe the fun and all the planets muft, in that cafe, be added to his one t 406 ] CHE any propriety, or without the greatcft folecifm, be laid CHeruIi-'i. and dclcrihed to fall down before and worfhip other ' » emblematical reprefentations of the fame divine nature and perfeftioiis : And therefore, whatever thefe beafts were emblems of, they could not be tlierubim in Mr Hutchlnfon's fenle ot that word ; it being as coritrary to the rational explanation of a viiion to fay that one emblem of the divinity fllould worlhip another emblem of it, as it is contrary to the reafon ot mankind, 'and to all our notions either of the Godhead or of worihjp, to fay that the Trinity worfhipped the Trinity, or any one t'trfon in the Trinity." This objection is admitted by our learned author to be a very plaufible cue. To us it appears unanfwerable. He aniwers it, however, in the following words : " Let it be carefully obferved, that thefe reprefenta- tions in Rev ch. v. and xix. are not only vliional but hieroglyphical, and therefore mull be explained accord, ing to the analogy of fuch emblematical exhibitions ; and as at ver. 6. ' the lamb, as it had been flain, having feven horns and feven eyes, (landing in the midll of the throne, and of the four animals, and of the four-and- twenty elders,' is evidently iymbolical of the Lamb of God now raifed from the dead, and inverted with all knowledge and power both in heaven and in earth ; fo ' the four animals falling down before him' (ver. 8.), and, as it is expreffed (ch. xix. 4.), ' worftipping God who fat upon the throne,' muft, in all reafon, be ex- plained fymbolically likewife, not from any abftraft or metaphyfical notions we may have framed to ourfelves of worfhip in general, but from the fpecific and pe- culiar circumilances of the cafe before us. Thus, likewife, when in i Chron. xxix. 20. ' All the con- fubftance, which would no longer appear under a triple gregation worfhipped Jehovah and the king, namely form. Could it indeed be proved, that all men from David, the worfhip to both is expreffed by the fame Adam downwards, who made ufe of cherubic figures ftrong phrafe — ': ■nnnii* proftrated themfelves to, LXX. for the very fame purpofe with the ancient Jews, belie- »p5iirav. ; yet furely no one will fay that the people ited that fire, air, and light, are different modifications meant to worfhip David as God, but only to acknow- of the fame fubftance, their belief, though erroneous, ledge him as king. So Adonijah, who had contefted would be a fufficient foundation for our author's reafon- the crown with Solomon, came, innwi and worfhipped «Ch.v. six, 4. ing ; but of this no proof is attempted, and certainly none that is fatisfaftory could be brought. Our learned authcir, indeed, takes much for granted without proof. He has not proved that anywhere the bull was the emblem or hieroglyphic oi Jire, the lion of light, or the eagle of air. We do not, it muft be owned, know that fuch hieroglyphics were not ufed in Egypt and other countries before the introduftion of alphabetical charafters ; but unlefs they were fo ufed by Adam, all that is here faid of the propriety of thefe smbltm.s muft go for nothing: Indeed we fee not their peculiar propriety. The tawny colour, flowing mane, and fiercenefs of the lion, might, for any thing that we can perceive to the contrary, reprefent Jire as fitly as the horns, curling hair, and fury of the bull ; and if ■it be true, as is generally faid, that the eagle can look jleadily on the fun, he feems, of all the three, to be the fitteft emblem of light. But there are other objcdlions to this interpretation of the word cherubim. The four animals in the Revela- tion, which were undoubtedly cherubim, as well as the four and twenty elders, fell down before the Lamb, i. and worfhipped God*. Now, fays Dr Gregory Sharp, " it is fcarce to be conceived, if thefe four beafts were re- King Solomon (l Kings i. 53.), not as God doubt- lels, but as king, thereby furrenderiiig his own claim to the throne. However ' contrary therefore it may be to the reafon of mankind, and to all our notions either of the Godhead or of worfhip, to fay that the Trinity wovlhipped the Trinity, or any one Perfon of the Tri- nity,' /'. e. with divine worfhip as a creature worfhips his Creator ; yet it is by no means contrary to the ra- tional and fcriptural explanation of an emblematic vi- fion, to fay that the in'croglyphical emblems of the whole ever-bleffed Trinity fell down and worfhipped the hieroglyphical emblem of the God-man, or God who fat upon the throne. Since fuch falling down, proilration, or worfhipping, was the ufual fymboHcal aft, as it ftill is in the eaft, not only of divine worfnip, but of acknowledging the regal power to be in the per- fon fo worfhipped ; and thefe afts of the cherubic ani- mals in Rev. v. 6. xix. 4. meant nothing more than either a ceffion of the adminiftration of all divine power to Chrifl God-man, or a declaration of the divine Per- fons, by their hieroglyphical reprefentatives, that He muft reign till all his enemies were made his footilool. Comp. Mat. xxviii. 18. 1 Cor. xv. 25." With every inclination to honour the memory of Mr prefeiitativesof the divine jierfons, that they could with Parkhurft, who was certainly a fcholar, and, which is of CHE [ 407 ] CHE Cher*, of more value, a pious and a good man, we cannot help horfe ; then the ionl ; and before them all, (onr foot -fol- — V— ' confidcrlng this anfwer as mere trilling. In the i8th diers ; but the iotit mud be placed in the angle of the Pfalm, the Lord is faid to "ride upon a cherub;" board." and in Ezekiel, chap. i. there is faid to have "been " From this palTage (fays the prefident) it clearly- over the heads of the cherubim a throne, and upon that appears, that an army with its four an^js muft be pla- throne the likenefs or appearance of a pwn," whom we ccd on each fide of the board, fince an dtpbant could take to be the Son of God incarnate. But is there not Hand, in any other pofition, on the left hand of each any country in which the regal power of the fovereign li'tg ! an^l RADHACANr (a Pandit) informed mc, that is acknowledged by his riding, not upon his fubjetils, the board confilled, like our's, of 64 fquares, half of thein but upon other co-equal fovereigns ? or, in which it is occupied by the forces, and half vacant. Pie added, the cuftom for the fovereign to place his viceroy (for that this game is mentioned in the oldeft law-books, fuch our Saviour in his human nature certainly is) in and that it was invented by the wife of a king, to amiife his throne above himfelf ? him with an Image of war, while his metropolis was be- We muft therefore confefs, that we know not of fieged, in the fecond age of the world. A Jhi[> or boat what the cherubic figures were emblematical, and that is abfurdly fubftitutcd, we fee, in this complex game for he who labours to eftablifh the doftrine of the ever the rat'h, or armed chariot, which the Bengatefe pro- blefTed Trinity by fuch criticifms and reafonings as thofe nounce rot'h, and which the Perfians changed into rohh ; which we have examined, is either a fccret enemy to whence came the rook of fome European nations ; as that dodtrine, or a very injudicious friend. the vierge zndful of the French are fuppofed to be cor- CHESS, the celebrated game, of which a copious ruptions of ferz and Ji/, the prime mini/ler and elephant Chefs. llAfialhRi fearcbeiy vol a. Mem. 9. account has been given in the Encyclopaedia, is affirm- ed by Sir William Jones to have been invented by the Hindoos. " If evidence were required to prove this faft (fays he *), we may be fatisfied with the teftimo- of the Perfians and Arabs." As fortune is fuppofed to have a great fliare in de- ciding the fate of a battle, the ufe of dice is introduced into this game to regulate its moves ; for (fays the Pu- ny of the Perfians, who, though as much inclined as ran) " \i cinque be thrown, the king or a patun muft be other nations to appropriate the ingenious inventions of moved ; if qualre, the elephant ; if trois, the horje ; and a foreign people, unanimoufly agree that the game was if deux, the boat. The king paffes freely on all fides, imported from the weft of India in the fixth century of but over one fquare only ; and with the fame limitation our era. It feems to have been immemorially known ihe panvn moves, but he advances ftraight forward, and in Hindojlan by the name of Cheturanga, i. e. the four kilis his enemy through an angle. The elephant marches anga's, or members of an army ; which are thtfe, ele- in all direftions as far as his driver pleafes ; the horfe phants, horfes, chariots, and foot foldiers ; and in this runs obliquely, traverfing the fquares; and the /hip fenfe the word is frequently ufed by epic poets in their goes over two fquares diagonally." The elephant, we defcriptions of real armies. By a natural corruption of find, has the powers of our queen, as we are pleafed to the pure Sanfcrit word, it was changed by the old Per- call the general or minijler of the Perfians ; and thejhip fians into Chetrang ; but the Arabs, who foon after has the motion of the piece to which we give the unac- took poffeffion of their country, had ncitlier the initial countable appellation of lifhop, but with a rcftriftion nor final letter of that word in their alphabet, and con- which muft greatly leffen its value. fequcutly altered it further into Shetranj, which found In the Purjn are next exhibited a few general rules its way prefently into the modern Perfian, and at length and fuperficial direflions for the conduft of the game, into the dialeifts of India, where the true derivation of Thus, " the paiuns and the /Zi/^ both kill and may be the name is known only to the learned. Thus has a voluntarily killed ; while the kivg, the elephant, and the " very fignificant word in the facred language of the horfe, may (lay the foe, but muft not expofe themfelves = Brahmins been transformed by fucceftive changes into to be flain. Let each player preferve his own forces" axedrez, fcacchi, echecs, chefs, and, by a whimfical con- with extreme care, fecuring his ling above all, and not ourrence of circumftances, has given birth to the Eng- facrificing a fuperior to keep an inferior piece." Here lifli word check, and even a name to the exchequer of (lays the prefident) the commentator on the Purjn ob- Great Britain." lerves, that the horf, who has the choice oi eight moves - It is confidently afferted that Sanfcrit books on chefs from -any central pofition, muft be preferred to thefhip, exift in Bengal ; but Sir William had feen none of them which has only the choice of four. But the argument when he wrote the memoir which we have quoted. He would not hold in the common game, where the bi/hop exhibits, however, a defcription of a very ancient Indian and totver command a whole line, and where a knight is game of the fame kind, but more complex, and in his always of lefs value than a tower in afkion, or the bi- opinion more modern, than the iimple chefs of the Per- fhop of that fide on which the attack is begun. " It ^■ans. This game is alfo called Chaturanga, but more is by the overbearing power of the elephant (continues frequently Chatiiraji, or the your kings, lince it is played the Purun) that the king fights boldly ; let the whole by four perfons reprefenting as many princes, two allied army, therefore, be abandoned in order to fecure the armies combating on each fide. The defcription is ta- elephant. The king muft never place one elephant be- ken from a book called Bhainijhya Piiran ; in which the fore another, unlefs he be compelled by want of room, form and principal rules of this faAitlous warefare are for he would thus commit a dangerous fault ; and if he thus laid down : " Eight fquares being marked on all can flay one of two hoftile elephants, he muft deftroy fides, the red army is to be placed to tlie eaft, the green that on his left hand." to the fouth, the yellow to the weft, and the black to All that remains of the paflage which was copied for the north.. Let the elephant (fays the author of the Sir William Jones relates to the feveral modes in which Puran) Hand on the left of the king ; next to him the a partial fuccefs or complete victory may be obtained '. by. CHE [ 408 ] . C H I ~ Chefs, by any one of the four players ; fur, as in a difpute be- By the author of the Military Guide, this is faid to be Chicha Chevretee. t^yggp (^v„ allies, one of the kings may fometimes af- the raoft ufeful of all the inventions for raifing guns . H * fume the command of all the forces, and aim at a fepa- into their carriages; and it ieems thefe inventions have ""ney. rate conquell. Firft, " When any one king has placed been many. - ' himfelf on the fquave of another king (\vlilc:h advantage CHICHA, the name given by the natives to the is cnWed Jiribu/'iinn or the //von:) he wins a ilake, which iHand of Jeflo, which lies to the fouth of Oku-JelFo, or is doubled if he kill the adverfe monarch when he feizes Segalian ifland. See Segalian in this Supplement. Ills place ; and if he can feat Uimfclf on the throne of CHIMERE, t!;e upper robe worn hy bidiops in his allv, he takes the command of the whole army." church and in the Houfe of Peers, to which the lawn Secondly, " If he can occupy fucccflively the thrones fleeves arc generally fewtd. Bciore the Reformation, of all the three princes, he obtains the victory, which is and even after it till the reign of C^neen Elizabeth, the named cheiuraji; and the ftake is doubled If he kill the chimere was always of fcarlst J'llk ; but bifhop Hooper, laft of the thre«, juft before he takes poffeflion of his fcrupling firft at the robe itfclf, and then at the colour throne ; but if he kill him on his throne, the Hake is of it, as too liglit and gay for the epifcopal gravity, the quadrupled. Both in giving the _y7;;/' the firll ever feen at Rome, he affixed hio arms, which were ftill remaining in the time of De Gataris, who died of the plague in 14C5. Though chimneys have been thus long in ufe, they are yet far enough from being brought to perfeftion. 10 ] CHI There is hardly a modern houfe, efpecially if highly fi- Chimney. niflied, in which there is not one room at leaft liable to "~~N be filled with fmoke when it is attempted to be heated by an open fire ; and there are many houfts fo infefted with this plague as to be almoft uninhabitable during the winter months ; not to mention other great defects in common chimneys, which not being fo obvious have attracted lefs attention. ^ Many ingenious methods have been propofed to cure fmokey chimneys in every iltua- tion (fee Smoke, EncycL) ; but Count Rumford's Ef- fay on this fnbjeft contains the moft valuable dired'lions that we have feen, not only for removing the inconve- - niency of fmoke, but likewife for increafing the heat of the room by a diminiflied confumption of fuel. To thofe who are at all acquainted with the naturd and properties of elaftic fluids, it mull be obvious, that the whole myftery of curing fmokey chimneys confifts in finding out and removing the accidental caufes which prevent the heated fmoke from being forced up the chimney by the preflure of the cool and therefore hea- vier air of the room. Though thefe caufes are various, yet, fays our author, that which will moft commonly be found to operate, is the bad conftruftion of the chim- ney in the neighbourhood of the Jire-place. " The great fault of all the open fire-places or chimneys for burning wood or coals in an open fire now in common ufe is, that they are much too large ; or rather it is the throat of the chimney, or the lower part of its open canal, in the neighbourhood of the mantle, and immediately over the fire, which is too large." To this faujt, therefore, the attention fhould be firft turned in every attempt which is made to improve the conftruftion of chimneys ; for however perfect a fire- place may be in other refpefts, if the opening left for the paflage of the fmoke is larger than is neceflfary for that purpofe, nothing can prevent the warm air of the room from efcaping through it; and whenever this hap- ' pens, there is not only an unneceftary lofs of heat, but the warm air which leaves the room to go up the chim- ney being replaced by cold air from without, draughts of cold air cannot fail to be produced in the room, to the great annoyance of thofe who inhabit it. But al- though both thefe evils may be effectually remedied by reducing the throat of the chimney to a proper fize, yet in doing this feveral precautions will be neceffary. And firft of all, the throat of the chimney ftiould be in its proper place ; that is to fay, in that place in which it ought to be, in order that the afcent of the fmoke may be moft facilitated : now as the fmoke and hot vapour which rife from a fire naturally tend iipiuards, the pro- per place for the throat of the chimney is evidently perpendicularly over thejire. But there is another circumftance to be attended to in determining the proper place for the throat of a chimney, and that is, to afcertain its diftance from the fire, or hoiv far above the burning fuel it ought to be placed. In determining this point there are many things, to be confidered, and feveral advantages and difadvan- tages-to be weighed and balanced. As the fmoke and vapour which afcend from burn- ing fuel rife in confequence of their being rarefied by heat, and made lighter than the air of the furrounding atmofphere; and as the degree of their rarefaction, and confequently their tendency to rife, is in proportion to the inteofity of their Ueatj and further, as they are hot- ter C H I [ 4 Chimney, ter near the fire than at a greater diflanee from It — It is *— — V ' clear that the nearer the throat of a cliiinney is to the fire, the iUonger will be what is commonly called its draught, and the lefs danj^er there will be of its fmoking. But, on the other liand, when the draught of a chim- ney is very ftrong, and particularly when this ftrong draught is occafioned by the tliroat of the chimney be- ing very near the fire, It may fo happen that the draught of air into the fire may become fo ilrong as to caufe the fuel to be confumed too rapidly. There are likewife fevcral other inconveniences which would attend the placing of the throat of a chimney very near the burn- ing fuel. The pofition of the throat of a chimney being once determined, the next points to be afcertained are its fize and form, and the manner in which it ought to be con- nedled with the fire-place below, and with the open ca- nal of the chimney above. But as thefe inveftigations are intimately connefted with thofe which relate to the form proper to be given to the fire-place itielf, we muft confider them all together. Now the defign of a chimney fire being fimply to warm a room, it is neceflary, firft of all, to contrive matters fo that the room (hally be aftually warmed ; fe- coadly, that it be warmed with the fmalltft expence of fuel poffible ; and, thirdly, that in warming it, the air of the room be preferved perfeftly pure, and fit for re- fpiration, and free from fmoke and all difagreeable fniells. To determine in what manner a room is heated by an open chimney fire, it will be neceflary firft of all to find out under luhat form the heat generated in the combuftion of the fuel exilts, and then to fee how it is communicated to thole bodies which are heated by it. In regard to the firll of thefe fubjedls of inquiry, it is quite certain that the heat which is generated in the combuftion of the fuel exifts under /•a'o perfeftly diftlnft and very different forms. One part of it is combined with the fmoke, vapour, and heated air which rife from the burning fuel, and goes off" with them into the upper regions of the atmofphere; v/hile the other part, which appears to be uncombined, or, as fome ingenious philofo- phers ha-, e fuppofed, combined only with light, and therefore called radiant heat, is fcnt off^ from the fire in rays in all poffible direftions. With refpeft to the fecond fubjeft of inquiry, name- ly, how this heat, exifting under thefe two different forms, is communicated to other bodies, it is highly probable that the combined heat can only be commu- nicated to other bodies by aHual contafl with the body with which it is combined ; and with regard to the rays which are fent off by burning fuel, it is certain that they communicate or generate heat only -when and -where they are Hopped or abforbed. In paffing through air, which is traiifparent, they certainly do not communi- cate any heat to it ; and it feems highly probable that they do not communicate heat to folid bodies by which they are reflefled. As it is the radiant heat alone which can be em- ployed in warming a room, when fuel is burnt for this purpofe in an open fire-place, it becomes an objeft of much importance to determine how the greateft quan- tity of It may be generated in the combuftion of the fuel, and how the greateft proportion jjoffible of that generated may be brought into the room. II ] CHI Now the quantity of radiant heat generited in the Chimiv*y combuftion of a given quantity of any kind of fuel de- '~~~^'~~'^ pends very much upon the management of the fire, or upon the manner in which the fuel is confumed. When the fire burns bright, much radiant heat will be fent off from it ; but when it is fmolhered uj>, very little will be generated, and indeed very little combined heat that can be employed to any ufeful purpofe : inoft of the heat produced will be immediately expended in giving elafticity to a thick denfe vapour <.r fmoke, which will be fecn rifing from the fire ; and the combuftion being very incomplete, a great part oi the inflammable matter of the fuel being merely rarefied and driven up the chimney without being inflamed, the fuel will be waft- ed to little purpofe. And hence it appears of how much importance it is, whether it be confidered with a view to economy, or to clcanlinefs, comfort, and ele- gance, to pay due attention to the management of u chimney lire. Nothing can be more perfedlly void of common fenfe, and wafteful and llovenly at the fame time, than the manner in which chimney fires, and particularly where coals are burned, are commonly managed by ier- vants. They throw on a load of coals at once, through which the flame is hours in making its way ; and fre- quently it is not without much trouble that the fire is prevented from going quite out. During ihia time no heat is communicated to the room ; and what is ftill worfe, the throat of the chimney being occupied mere- ly by a heavy denfe vapour, not poffefTed of any confi- derable degree of heat, and confequently not havino- much elafticity, the warm air of the room finds lefs dif- ficulty in forcing its way up the chimney and efcaping than when the fire burns bright. And it happeui not unfrequently, efpecially in chimneys and fire-places 111- conftrudled, that this current of warm air from the room which prelTes into the chimney, crof^no- upon the current of heavy fmoke which rites flowly from the fire, obftrufts it in its afcent, and beats it back into the room : hence it is that chimneys fo often fmoke wheu too large a quantity of frefli coals is put upon the fire. So many coals fhould never be put on the fire at once aa to prevent the free paffage of the flame between them. In fliort, a fire fhould never be fmothered; and when proper attention is paid to the quantity of coals put on, there will be very little ufe for the pocker ; and this circuinftance will contribute very much to cleanlinefs, and to the prefervation of furniture. As we have feen what is ireceifary to the generation of the greateft quantity of radiant heat, it remains to be determined how the greateft proportion of that which is generated and fent off from the fire in all direiftions may be made to enter the room, and aflift in v?3rming it. This muft be done, firft, by caufing as many as pof- fible of the rays, as they are fent off from t'le fire in ftraight lines, to come direHly into the room ; which can only be etfefted by bringing the fire as far forward as poffible, and leaving the opening of the fire-place a« wide and as high as can be done w ithout inconvenience : and, fecondly, by making the fides and back of the fire-place of (uch a form, and ccn.lruftlng them of fuch materials, as to caufe the dircft rays from the fire, which ftrike againft tlieni, to be lent into the room by icfleftion in the greateft abundance. Now it will be found upon examination, that the beft 3 F 2 f jrm CHI [41 Cliimney. form for the vertical fides of a fire-pkcc, or the covir^^s ' ^ ' (as they are called), is that of an upright plane, ma- king an angle with the plane of the back of the fire- place of about 135 degrees. — According to the prefcnt conftruftion of chimneys, this angle is fometimes only «)0, and very feldom above 100 or 110 degrees ; but it is obvious, that in all thcfe cafes the two fides or co- verings of the fire-place are very ill contrived for throw- ing into the room by refleftion the rays from the fire which fall upon them. With regard to the materials which (liouM be em- ployed in the conftrudlion of fire-places, particularly the backs and covings, it is obvious that thofe are to be preferred which alforb the leaj}, and of qourfe re- jleS the greateft quantity of radiant heat. Iron, there- fore, and, in general, metals ot all kinds, are the very worft materials which can pofiibly be employed for the backs and covings of chimneys ; whilil fire-ilone white- waflied, or common bricks and mortar, covered with a thin coating of plafter, and white-wafhed, anfwer the purpofe extremely well. A white colour fhould, in- deed, be always given to the infide of a chimney of whatever materials It be conftrufted ; and black, which is at prefent fo common, fhould be carefully avoided, becaufe white reflefts the moft, and black the lead, ra- diant heat. The grate, however, cannot well be made of any thing elie than iron ; but there is no neceflity whatever for that immeiife quantity of iron which fur- rounds grates as they are commonly fitted up, and which not only renders them very expenfive, but efl'en- tially injures the fire-place. To have only pointed out the faults of the chimneys in ufe, without fhevving how thefe faults may be corredl- ed, would have been a work of very little value ; but the Count's Treatife is complete, and contains the plain- eft diredlions for the conftrudlion of fire-places. Thefe direftions are introduced by an explanation of forae technical words and expreG'ions. Thus, by the tl.-rcat of a chimney, already mentioned, he means the lower extremity of its canal, where it unites with the upper part of its open fire-place. 7 his throat is commonly found about a foot above the level of the lower part of the mantle, and it is fometimes contraiSed to a fmaller fize than the reft of the canal of the chimney, and fome- times not. Plate XX. Fig. 1. fliews the feftion of a chimney on the com- mon conftrudtlon, in which d e is the throat. Fig. 2. fhews the fedtion of the fame chimney altered and improved, in which di is the reduced throat. The brea/l of a chimney is that part of it which is immediately behind the mantle. It is the wall which forms the entrance from below into the throat of the chimney in front, or towards the room. It is oppofite to the upper extremity of the back of the open fire-place, and parallel to it : in ftiort, it may be faid to be the back part of the mantle itfelf. — In the figures i, and 2. it is marked by the letter d. The width of the throat of the chimney {^d e fig. i.and di fig. 2.) Is ta- ken from the brcaft ot the chimney to the back, and its lengtli is taken at right angles to its width, or in a line parallel to the mantle [a fig. I. and 2.). The bringing- forwaid of the fire into the room, or rather bringing it nearer to the front of the opening of the fire-place, and the diminiftiing of the throat of the chimney, being two objefts principally had in view in 2 ] CHI the alterations in fire-places propcfcd by the Count, it CMmnty. is evident that both thefe may be attained merely by ^— v— — ' bringing forward the back of the chimney. The only queftioii therefore is. How far it (liould be brought for- ward ? The anfwer is fliort, and eafy to be under- ftood ; bring it forward as far as poflibie, without di- mlniihing too much the pafTage which niuft be left for the fmoke. Now as this pafiilge, which in its narrow- eft part he calls the throat of the chimney, ought, for rea- fons which have been already explained, to be imme- diately, or perpendicularly over the fire, it is evident that the back of the chimney muft always be built per- feiSly upright. To determine, therefore, the place for the new back, or how far precifely it ought to be brought forward, nothing more is neceflary than to af- certaln how wide the throat of the ciilmney ought to be left, or what fpace muft be left between the top of the breaft of the chimney where the upright canal of the chimney begins, and the new back of the fire-place carried up perpendicularly to that height. Numerous experiments have convinced the Count, that, all circumrtances being well confidered, and the advantages and difadvantages compared and balanced, four inches is the beft width that can he given to the throat of a chin;ney, whether the fire-place be deftined to burn wood, coals, turf, or any other fuel. In very large halls where great fires are kept up, it may fome- times, though very rarely, be proper to increafe this width to four inches and a half, or even to five inches. The next thing to be confidered is the width which it will be proper to give to the back of the chimney ; and, in moft cafes, this ftiould be one-third of the width of the opening of the fire place in front. It is not in- deed abfulutely neceflary to conform with rigour to this declfion, nor is it always poflibie ; but it fliould inva- riably be conformed to as far as circumftances will per- mit. Where a chimney, fays the Count, is defigned for warming a room of a middling fize, and where the thicknefs of the wall of the chimney in front, meafured from the front of the mantle to the breaft of the chim- ney, is nine inches, I (hould fet off four inches more for the width of the throat of the chimney, which, fuppo- fing the back of the chimney to be built upright, as it always ought to be, will give thirteen inches for the depth of the fire-place, meafured upon the hearth, from the opening of the fire-place in front to the back. In this cafe, thirteen inches would be a good fize for the width of the back ; and three times thirteen inches, or 39 inches, for the width of the opening of the fire- place iu front ; and the angle made by the back of the fire-place and the fides of it, or covings, would be jufl '35 degrees, which is the beft pofitlon they can have for throwing heat into the room. This pofition, in- deed. It may fometimes be impolTible to attain in alter- ing chimneys already built ; but a deviation from it of two or three degrees will be of no great corfequence ; . for the points of by much the greateft importance in al- tering fire-places upon the principles here recommend- ed, are the bringing forward the back to its proper place, and making it of the proper width. Provifion, however, muft be made for the paffage of the chlmney-fweeper up the chimney; and this may eafily be done in the following manner : In building up the new back of the fire-place ; when this wall (which need never be more than the width of a fingle brick CHI ^ [ 4 Chinwey. brick in thicknefs) is brought tip fo lifgli that there ^" "V remains no more than about ten or ilcvcn inches be- tween what is then the top of it and tlie inliJe of the mantle, or kiwer eKtrcmitv of the bread ot the chim- ney, an opening or door way, eleven or twelve inches wide, mult be begun in the middle of the back, and continued quite to the top of it, which, according to the height to which it will commonly be neccflary to carry up the back, will make tiie opening abundantly fufficicnt to let the chimney-fweeper pafs. When the fire-place is fini(hed, this door-way is to be clofed by a tile or fit piece of ftone placed in it without mortar, and by means of a rabbit made in the brick-work, confined in its place in kich a manner as that it may be eafily removed when the chimney is to be fwept, and re- flored to its place when that work is over. Of this contrivance the reader v/ili be able to form a clear con- ception from fig. 2. which reprefents the feftion of a chimney after it has been properly altered from what is exhibited in fig. I. In this improved chimney k I is the new back of the fire-place ; It the tile or fione which clofes the door-way for the chimney-fxveepev ; d i the throat of the chimney narrowed to four inches ; a the mantle, and h the Hone placed under the mantle, fuppofed to have been too high, in order to diminifh the height of the opening of the fire-place in front. It has been obferved above, that the new back, which it will always be found neceffary to build in order to bring the fire fufficiently forward, in altering a chim- ney conilrufted on the common principles, need never be thicker than the width of a common brick. The fame may be faid of the thicknefs neceffary to be given to the new fides or covings of the chimney ; or If the new back and covings are conftrucfted of Hone, one inch and three quarters, or two inches in thicknefs, will be fufficicnt. Care fhould be taken in building up thefe new walls to unite the back to the covings in a folid manner. Whether the new back and covings are conftrufted of flone or built of bricks, the fpace between them and the old back and covings of the chimney ought to be filled up, to give greater folldity to the fbni(i|ure. This may be done with loofe rubbifh, or pieces of broken bricks or llones, provided the work be flrengthened by a few layers or courfes of bricks laid in mortar ; but It will be indifpcnfably neceffary to finifh the work where thefe new walls end, that is to fay, at the top of the throat of the chimney, where it ends abruptly in the open canal of the chimney, by a horizontal courfe of bricks well fecured with irjortar. This courfe of bricks will be upon a level with the top of the door-way left for the chimney-fweeper ; and the void behind the door- way mu(l be covered with a horizontal flone or tile, to be removed at the fame time the door is removed, and . for the fame purpofe. From thefe defcriptlons it is clear, that where the throat of the chimney has an end, that is to fay, where it enters into the lower part of the open canal of the chimney, there the three walls wliich form the two co- vings and the back of the fire-place all end abruptly. It is^ of much importance that they fhould end in this manner ; for were they to be floped outward, and rai- fed in fuch a manner as to fwell out the upper extremi- ty of the throat of the chimney in the form of a trum- pet, and increafe it by degrees to the fize of the canal ^3 ] C H I of the chii"ney, this manner of uniting the lower e.\. Chimney, tremity uf tlic canal of the chlnuicy with the throat ' v -^ would tend to afTill the winds, which may attempt to blow down the chimney, in forcing their way through the throat, and throwing the fmoke backward into the room ; but when l he t hi oat of I he chimney ends abrupt- ly, and the ends of the new walls form a flat horizontal furface, it will be much more difficult for any wind from above to find and force its way through the nar- row paffage of the throat of the chimney. As the two walls which form the new covings of the chimney are not parallel to each other, but Inclined, prefenting an oblique furface towards the front of the chimney, and as they are built perfeftly upright, and quite flat, from the hearth to the top of the throat, where they end, it Is evident that an horizontal fcftlon of the throat will not be an oblong fquare ; but its de. viaclon from that form is a matter of no confequence ; and no attempts (liould ever be made, by twifling the covings above where they approach the breaft of the chimney, to bring It to that form. All twills, bends, prominences, excavations, and other irregularities of forrn in the covings of a chimney, never fail to produce eddies in the current of air which is continually paffing into, and through, an open fire-place in which a fire is burning ; and all fuch eddies dKlurb either the fire or the afcending current of fmoke, or both ; and not un- frequently caufe the fmoke to be thrown back into the room. Hence it appears, that the covings of chimneys fliould never be made circular, or in the form cf any- other curve, but always quite flat. For the fame reafon, that Is to faj-, to prevent ed- dies, the brcafl of the chimney, which forms tlrat fide of the throat that is In front or nearefl to the room, fhould be neatly cleaned off, and its furface made quite regular and fmooth. This may be eafily done by co- vering it with a coat of plafler, which may be made tliicker or thinner In different parts, as may be neceffa- ry in order to bring the brtafl of the chimney to be of the proper form. With regard to the form of the breaft of a chimney, this IS a matter of very great importance, and which ought always to be particularly attended to. The worfl form it can have Is that of a vertical plane or upright flat ; and next to this the worfl form is an inclined plane. Both thefe forms caufe the current of warm air from the room, which will, in fpite of every precaution, fometimes find its way into the chimney, to crofs upon the current of fmoke which tifes from the fire in a man- ner mofl likely to embarrafs it in Its afcent, and drive it back. The current of air which, pafiing under the mantle, gets into the chimney, fliould be made graihally to bend its courfe upwards ; by which means it will unite quietly with the afcending current of fmoke, and will be lefs likely to check it, or force it back into the room. Now this may be effefted with the greateil cafe and certain- ty, merely by rounding off the breaft oi the chimney or back part of the mantle, inftead of leaving it flat or full of holes and corners ; and this of courfe ought always to be done. Having thus afcertained the form and pofitlon of the new covings, the ingenious author next turns his atten- tion to the height to which they fhould be carried. This will depend not only on the height of the mantle, , but C H I [ 4'4 1 C H I -Cl.im- ey. but alfo, and more efpecially, on tlie height of the » bread (if the eliimney, or of that part of the chimney where the bread ends and the iipriglit canal begins. — The bad; and covings iiuid rife a few inches, five or iix for indarice, higher than this part, othcrwifc the throat ot ilie ciiimncy will not be pro])erly formed ; but no advantage would he gained by carrying them ^hi^he,-._ One important circumdance refpefting chimney fire- places Hill remains to be confidered ; and that is the grate. In placing the grate, the thing principally to be attended to is, to make the back of it coincide with the back of the fire place. But as many of the grates now in common ufe will be found to be too large, when the fue pkees are altered and improved, it will be ne- ceffary to diminifli their capacities by filling them up at the back and fides with pieces of fire done. When this is done, it is the front of the flat piece of fire-done which is made to form a new back to the grate, which mud be made to coincide with, and make part of the back of the fire place. — But in diminifhing the capaci- ties of grates with pieces of fire-done, care mud be ta- ken not to make them too narroiu. The proper width for grates dcdincd for rooms of a middling fize will be from fix to eight inches, and their length may be diminiflied more or lefs according as the room is heated with more or lefs difficulty, or as th.e weather is more or lefs fevere. — But where the width of a grate is not more than five inches it will be very tlifficult to prevent the fire from going out. It frequently happens that the iron backs of grates are not vertical, or upright, but inclined backwards. — When thefe grates are fo much too wide as to render it iiecelTary to fill them up behind with fire-done, the inclination of the back will be of little confequence ; for by making the piece of done with which the width of the grate is to be diminiihed in the form of a wedge, or thicker above than below, the front of this done, which in effeft will become the back ot the grate, may be made perfeftly vertical ; and the iron back of the grate being hid in the folid work of the back of the fire-place, will produce no effeft whatever; but if the grate be already fo narrow as not to admit of any dimi- nution of its width, in that cafe it will be bed to take away the iron back of the grate entirely, and fixing the grate firmly in the brickwork, caufe the back of the fire-place to ferve as a back to the grate. Where grates, which are defigned for rooms of a middling fize, are longer than 14 or 15 inches, it will always be bed, not merely to diminifh their lengths, by filling them up at their two ends with fire-done, but, forming the back of the chimney of a proper width, ■without paying any regard to the length of the grate, to carry the covings through the two ends of the grate in fuch a manner as to conceal them, or at lead to con- ceal the back corners of them in the walls of the covings. Had thefe direftions been duly attended to by the mafons who in Scotland pretend to alter chimneys on the principles of Count Rumford, we diould not have .obferved fo many of the grates placed by them jutting out beyond the mantle of the chimney ; nor of courfe heard fo many complaints of rooms being rendered more fmokcv, and the confumption of fuel increafed by thefe Ct iir.ney. pretended iniprovtmcnts. But when the grate is not " * ' fet in its proper place, when its doping non Lack is retained, when no pains have been taken to make its ends coincide with the covliigs.of the fire-place, when tlie mantle, indead of having its back rounded od, is a vertical plane of iron cutting the column of fmokc which rifes beneath it, and, above all, when the throat of the chimney, indead of four, is made, as we often fee, fourteen inches wide ; let it be remembered, that not one of Count Rumford's direftions has been fol- lowed, and that his principles have as little to do with the condrudlion of fuch a chimney as with the building of the wall of China or the pyramids of Egypt. To contribute our aid to prevent thefe blunders for the future, we diall here fubjoin the Count's directions for laying out the work ; not to indruA mafons and bricklayers, to whom we earnedly recommend the dudy of the effay itfelf (b), which contains much valuable in- formation that we have omitted ; but merely to give the country gentleman an opportunity of difcovering whe- ther the workmen whom he employs deviates far and needlcfslyfrom the principles which he pretendstofoUow. When a chimney is to be altered, after taking away the grate and removing the rubbidi, firil draw a draight line with chalk, or with a lead pencil, upon the hearth, from one jamb to the other, — even with the front of the jambs. The dotted line A B, fig. 3. may repre- fent this line. From the middle c of this line, (A B) another line c d is to be drawn perpendicular to it, acrofs the hearth, to the middle d, of the back of the chimney. A perfon mud now dand upright in the chimney, with his back to the back of the chimney, and hold a plumb-line to the middle of the upper part of the bread of the chimney ((/, fig. i.), or where the canal of the, chimney begins to rife perpendicularly ; — taking care to place the line above in fuch a manner that the plumb may fall on the line c d (fig. 3.) drawn on the hearth from the middle of the opening of the chimncv in front to the middle of the back, and an affidant mud mark the precife place e, on that line where the plumb falls. This being done, and the perfon in the chimney ha- ving quitted his dation, four inches are to be fet off on the line c d, from c, towards d i and the pointy, where thefe four inches end, (which mud be marked with chalk, or with a pencil), will (how how far the new back is to be brought forward. Through f, draw the line g h parallel to the line A B, and this line _f h will fliow the direAion of the new back, or the ground line upon which it is to be built. The line ;:/ will diow the depth of the new fire-place ; and if it diould happen that c f\i equal to about one-third of the line A B, and if the grate can be accommodated to the fire-place, indead of its being neceffary to accommodate the tire place to the grate ; ill that cafe, half the length of the line c f n to be fet off fromy on the line ^y A, on one fide to k, and on the other to /", and the line i k will lliow the ground line of the fore part of the back of the chimney. In all cafes where the width of the opening of the fire-place in front (A B) happens to be not greater, or not (b) It cods but two (liillings ; and he mud be a poor bricklayer indeed who cannot afford to pay that fura for inferufiion in the mod important, as well as mod difficult, part of his bufinefs. CHI [ 415 1 CHI Chimney, not more than two or three inches greater than thi-ee only four inches thick, four inches more adilcJ to it for Chimney. i—~-yf—' times the width of the new back of the chimney (i i), the width of the throat would have left tiie depth of '— v— this opening may be left; and lines drawn from ; to A, the fnt-place meafnred upon the hearth i c ojily eio-ht and from /- to B, will (how the width and pofition of inches, which would have been too little • a niche c the front of the new covings ; — but when the opening and e was therefore made in the new back of the firc- of the fire-place in front is ilill wider, it muft be redu- place for receiving the grate, which niche was fiy. inches ced ; which is to be done in the following manner: deep in the centre of it, below la inches wide for From f, the middle of the line A B, c a and c b equal in width to the grate,) and 23 inches high ■ fi- muft be fet off equal to the width of the back (i k), nilhing above with a femicircular arch, which in its added to half its width (fi) ; and lines drawn from i to higheil part, rofe fevcn inches above the upper part of a, and from k to b, will fhow the ground plan of the the grate. — The door- way for the chimney-fweepcr fronts of the new covings. which begins juil above the top of the niche may be When this is done, nothing more will be necefTary feen diftinctly in both the figures 6 and 7. The fpace than to build up the back and covings ; and if the fire- marked g, fig. 7. behind this door-way, may either be place is defigned for burning coals, to fix the grate in filled with Joofe bricks, or may be left void. The man- its proper place, according to the diredtions already ner in which the piece of ftoiic f, fig. 7. which is put given. — When the width of the fire-place is reduced, under the mantle of the chimney to reduce tlie height the edges of the covings a A and b B are to make a of the opening of the fireplace, is rounded off on the finiih with the front of the jambs. — And in general it infide in order to give a fair run to the column of fmoke will be beft, not only for the fake of the appearance of in its afcent through the throat of the chimney, is clear- the chimney, but for other reafons alfo, to lower the ly expreffed in this figure. The plan fig. r. and eleva- height of the opening of the fire-place whenever its tion fig. 6. (how how much the width of the opening •width in front is diminiflied. of the fire-place in front is diminiihed, and how the co- A front view of the chimney, after it has been thus vings in the new fire-place are formed, altered, is exhibited in fig. 4.. where the under part of A perfett idea of the form and dimenfion of the fire- the door-way is reprefented, as clofed by the white dot- place in its original (late, as alio after its alteration may- ted lines. be had by a careful infpeftion of thefe figures. When the wall of the chimney in front, meafured In chimneys, like that reprefented in figure R, where from the upper part of the breaft of the chimney to the the jambs A and B project far into the room and front of the mantle, is very thin, it may happen, and where the front edge of the marble flab 0, which forms efpccially in chimneys defigned for burning wood upon the coving, does not come fo far forward as the front of the jambs, the workmen in conftruciing the new co- vi,igs are very apt to place them, — not in the line c A, which they ought to do,— but in the line c 0, which is a great fault. — The covings of a chimney (hould never range be/jitu/ the front of the jambs, however thofe jambs may projeft into the room ; — bitt it is not abfo- the hearth, or upon dogs, that the depth of the chim ney, determining according to the directions here given, may be too I'mall. Thus, for example, fuppofing the wall of the chi.m- ney, in front, from the upper part of the breail of th chimney to the front of the mantle, to be only fou inches, (which is fometimes the cafe, particularly in lutely neceifary that the covings (hould maie a firiiP} rooms fituated near the top of a houfe), in this cafe, if with the internal front corners of the jambs, or that we take four inches for the width of the throat, this they (liould be continued from the back c, quite to the will give eight inches only for the depth of the fire- front of the jambs at ji They may finidi in front at place, which would be too little, even were coals to be a and b ; and fmall corners A, 0, a, mav be left for p'a- burnt inftead of wood. — In this cafe (fays the Count) cing the (hovels,- tongs, &c. I (hould increafe the depth of the fire-place at the Were the new coving to range with th'e front cdec hearth to 1 2 or 13 inches, and (hould build the back of the old coving 0, the obhquity of the new covint' perpendicular to the height of the top of the burning would commonly be too great ; or the aiiirle d c fuel (whether it be wood burnt upon the hearth or would exceed 135 degrees, ivbich it never Jhould do, coals in a grate) ; and then, (loping the back by a gen- or at leail never be more than a very fnw degrees. No tie incHnation forward, bring it to its proper place, inconvenience of any importance will arife from making that is to fay, perpendicularly under the back pur t of the the obliquity of the covings Icfs than what is here re- ihroat of the chimney. This flope, (which will bring commended ; but maay cannot fail to be produced by the back forward four or five inches, or juil as making it much greater. much as the depth of the fire-place is inereafed), Thefe extrads, which we have made fo liberally from , though it ought not to be too abrupt, yet it ought Count Rumford's eflay on chimney fire-places, will be to be quite finiihed at the height of eight or ten fufRcient, we hope, to bring fully within the conipre- inches above the fire, otherwife it may perhaps caufe the henlion of thofe who are acquainted with pneumatics chimney to fmoke ; but when it is very near the fire, and pneumatic chemiftry the principles on which chim. the heat of the fire will enable the current of rifing neys and fire-places (liould be conftrudted ; but fuch as fmoke to overcome the obftacle which this (lope will are in a great meafure (bangers to thefe fcicnces will oppofe to its afcent, which it could not do fo eafily do well to confult the efTay ilfelf. With a benevolence - were the (lope fituated at a greater dillance iroii" the which does him honour, the ingenious author has c.<- burning fuel. preflTed a widi that his dodrines on this important fub- Fig. 5, 6, and 7, (how a plan, elevation, and feftion jeft may be widely propagated ; and to encourarre ar. of a fire-place conllrufted or altered upon this principle, tills to (ludy them, he has declared to the public ?n ge- —The wall of the chimney in frojit at a, fig. 7. being neral," that as he dots not intend to take out himfJf, . C H I [ 4t6 ] C H 1 Clilmnay, q,. to fuffcr others to take out, any patent for any in- ■Sviecpeii. y^ntion of his which may be of pubh'c utility, all per- * foils are at full liberty to imitate them, and vend them, for their own emolument, when and where, and in any way they may think proper." CniMhEr-Siveepers are a clafs of men who earn their fubfiftence by clearing chimneys of foot, which occa- fions them to fmoke. While chimneys continued to be built in fo limple a manner, and of fuch a width as they are llill oblVrved to be in old houfes, they were fo eafily cleaned that this fervice could be performed by a fer- yant with u wifp of llraw, or a little brudiwood faften- ed to a rope; but after the flues, in order to fave room, were made narrower, or when feveral flues were united together, the cleaning of them became fo difficult, that they required boys, or people of fmall fize, accuiloraed to that employment. The firft chimney-fweepers in Germany came from Savoy, Piedmont, and the neigh- bouring territories. Thefe for a long time we.-e the - only countries where the cleaning of chimneys was fol- lowed as a trade ; and hence Profeffor Beckmann con- cludes with great probability, that chimneys were in- vented in Italy. The Lotharingians, however, under- took the bulincfs of chimney- fweeping alfo ; on which account the duke of Lotharingia was llyled the imperial Jire-majler. The fit ft Germans who condefceuded to clean chimneys were miners; and the chimney-fweepers in that empire ftill procure their boys from theforell of Hartz, where the greateft mines arc wrought. Very lately, and perhaps at prcfent, the greater part of the chimney-fweejjers In Paris wercSavoyards, many of them not above eight years of age, who, for the paltry fum of five fous, which they were obliged to fhare with tlreir avaricious mailer, would fcraii ble, at the hazard of their lives, through a narrow funnel fifty feet in length, and with their bcfoms clean it fiom foot and dirt. At what precife period chimncy-fweeping became a trade in England and Scotland, we have not been able to learn ; but among us, as well as e'lewhere, young boys are employed in this bufinefs, who are faid to be very harlhly treated by fellows who ftole them from the doors of cottages in the country. Tiiat children have been fometimes kidnapped by chimney-lweepers, we can have no doubt ; but that the praflice is frequent, we do not believe. We think however that the bufinefs might be wholly abolilhed ; for a narrow funnel might certainly, if not very crooked, be fwept by a buijdle of ftraw or brulhwood fullencd to a rope, as well as one that is wider: and the bricks which leparate the conti- guous flues we know to be lefs injured by this method of fweeping, when cautioufly gone about, than by fend- ing boys up the chimneys. On the 4th July 1796, letters patent were grant- ed to Daniel Davis, of the paiilh ot St Giles, Middle- fex, for his invention of a machine, by which he pro- pofes to fweep and cleanfe chimneys, and extinguifh chimneys on fire, without any perion going up the fame, as is now the pratlice. The machine conlifts of an apparatus of rack-work, of various lengths, which, by means of a hand-turn, is made to afcend the chim- ney. The lengths of the rack-work are joined toge- ther by means of mortices and tenons, with a fpring which holds them faft. In each length is a joint, by which the rack-work will accommodate itfelf to angles or turns in the ilues. To the lirit or uppermofl length is fixed a brufli of hair, or wire, or fpunge, or other China, elaftic fubftance as the occafion may require. ' v "' This invention is doubtlefs well calculated to anfwer the purpofe intended, and may perhaps be the means of diminifliing the number ot tliofe objedls of mifery, the unfortunate chimney-fweepers. CHINA is an empire of fuch antiquity and extent, the laws and culloms of the people are fo fmgular, a-nd the populoufnefs of the country fo very great — that it has attracted much of the attention of Europeans ever fince it was vifited in the 13th century by Marco Paulo the Venetian traveller. Of fuch a country it would be unpardonable not to give iome account in a work of this nature ; but vv'e have not, in truth, much to add to what has been faid of China and the Cisinefe in the Encyclopsdia Britannica. Since the article China in that work was publilhed, the court of Ptkin has indeed been vifited by an embaffy from Great Britain, and the origin of the people, as well as the antiquity of their empire, has been invelligated by Sir William Jones with his uiual diligence ; but from his memoir, pub- lillied in the feoond volume of the Afiatic Refearches, and from Sir George Staunton's account of the embaf- fy, there is not much to be cxtrafted which would be either amufing or inllruClive to our readers. We have already obferved from Grofier and others, that the Chinefe not only lay claim to the higheil an- tiquity, but even contend that their firft emperor was the firft man. Both thefe pofitions are controverted by Sir William Jones, who, though he allows the Chinefe empire to be very ancient when compared with the oldeft European ftate, is yet decidedly of opinion that it was not founded at an earlier period than the 12th century before the Chrlftian era ; and that the people, fo far from being aborigines, are a mixed race of Tar- tars and Hindoos. He begins his inveftigaticn with aflc- Jft mg, " Whence came the lingular people who long had ^ governed China, before they were conquered by the Tartars? On this problem (fays he*) four opinions* /^^//c^^ have been advanced, and all rather peremptorily afferted/Jor./jw, than fupported by argument and evidence. By a few *"'•"• writers it has been urged, that the Chinefe are an origi-"*''™' ^' nal race, who have dwelled for ages, if not from eterni- ty, in the land which they now polfefs. By others, and chiefly by the mlirionaries, it is infifted that they iprung from the fame ftock with the Hebreivs and the Arabs. A third affertion is that of the Arabs them- felves, and of M. Pauw, who hold it indubitable, that they were originally Tartan, defcending in wild clans from the fteeps of Imau« : And a fourth, at leaft as dogmatically pronounced as any of the preceding, is that of the Brahmans, who decide, without allowing any appeal from their decifion, that the Chinas (for fo they are named in Sanfcril) were Hindoos of the military caft, who, abandoning the privileges of their tribe, rambled in different bodies to the north-eaft of Bengal; and forgetting by degrees the rites and the re- ligion of their anceftors, ellabllftied feparate principali- ties, which were afterwards united in the plains and val- leys which are now poflefled by them. Of thefe opinions, Sir William having very complete- ly demollflied the firft tliree, proceeds to eftabhlh the fourth, which he confiders as interefting as well as nev» in Europe. In the Sanfcrit inftitutes of civil and reli- gious duties, revealed, as the Hindoos believe, by Menu the C 11 I [ 41 ChW.i. tlio fon of Bralima, we fin J (fays In) llic fullowiiig- cini- — % ous patTage : ' Many families of tlie military clafs, having gradually abandoned the ordinances of the Fiila, and the company of Brahmans, lived in a ftate of degradation ; as the people of Pundraca and Odra, tliofe of Dravira and Ccvtibnja, the Tavanas and Sacas, the Paradus and Piihhmas, the Chinas, and fome other nations.' A full comment on this text (contiiiucis the prefident) would be fuperfluous ; but fiiice the Icllimony of the Indian author, who, though not a divine perfonage, was certainly a very ancient lawyer, moralift, and hifto- rian, is direct and pofitive, diilntercfttd and unfufpeft- ed, it would decide the queilion before us if we could be flire that the word China fignifies a Chhwfe." Of this faft Sir William Jones took the very beft methods to be fatisfied. He confultcd a number of Pandits le- parately, who all alTured him that the word China has no other fignification in Sanfcrit ; that the Chinas of Menu fettled in a fine country to the north-eall of Gaur, and to the eall of Camanip and Napai ; that they had long been, and Hill are, famed as ingenious artiii- cers ; and that they (the Pandits) had themfelves feen old Chinefe idols, which bore a manifell relation to the primitive religion of India. He then laid before one of the beft informed Pandits a map of Afia ; and when liis own country was pointed out to him, the Pandit immediately placed his finger on the north-wellern pro- vinces of China, as the place wliere lie faid the Chinas of Menu firft eftabliihed themfelves. In the opinion of Sir William Jones, this is complete evidence that the Chinefe are defcended from an In- dian race ; but he does not believe that the Chinefe em- pire, as we now call it, was formed when the laws of Menu were collefted ; and for his calling this fai5l in queilion, he, offers reafons, which to us are perfectly fa- tisfadlory. By a diligent and accurate comparifon of an- cient Sanfcrit writings, he has been able to fix the period of the compilation of thofe laws at between 1000 and I ioo years before Chrill ; but by the evidence of Con- fucius himfelf, he proves, that if the Cliinele empire was formed, it could be only in its cradle in the 12th cen- tury before our era. In the fccond part of the work, intitled Ltin Tu, Confucius declares, that " although lie, like other men, could relate, as mere leflTons of mo- rality, the liiftories of the fnft and fecond imperial houfes, yet, _/or loan! of evidence, he could give no cer- tain account of them." Now, fays Sir William, if the Chinefe themfelves do not pretend that any hillorical monument exilled in the age of Confucius preceding the rife of their third dynally, about 1 100 years before the Chrillian epoch, we may juftly conclude that their empire was then in its infancy, and did not grow to ■ maturity till fome ages afterwards. Nay, he is inclined to bring its origin (bll lower down. " It was not, fays he, till the eighth century before the birth of our Sa- viour, that a fmall kingdom was erefted in the province of Shenji, the capital of which flood nearly in the 55tli degree of northern latitude, and about five degrees to the weft of Si-gan. That country and its metropolis were both called Chin ; and the dominion of its princes was gradually extended to the eaft and weft. The ter- ritory of Chin, fo called by the old Hindoos, by the Perfians, and by the Chinefe, gave its name to a race ef emperors, whofe tyranny made their memory fo un- popular, that the modern inhabitants of China hold the SuppL. Vol. I. Part II. 7 ] CHI word in al>horrence, and fpcak of themfelves as the China, people of a milder and more virtuous dynaily : but it *~~ is highly probable that the whole nation delcended from the Chinas of Menu, and mixing with the Tartars, by whom the plains of Honan and the more fouthcrn pro- vinces were thinly inhabited, formed by degrees the race of men whom we now Ice in poffeflion ol the no- bleft empire in Alia." In fupport of this opinion, which the accomphflied author offers as the refult of long and anxious Inqui- ries, he obferves, that the Chinefe have no ancient mo- numents from which their origin can be traced, even by plaufible conjcdlure ; that their fciences are wholly exotic ; that their mechanic arts have notlung in them which any fet of men, in a country fo highly favoured by nature, iiiiglit not have difcovercd and improved; that tlieir philofopliy feems yet in io rude a ftate as hardly to deferve the ai)pellation ; and that their popu- lar religion was imported from India in an age compa- ratively modern. He then inftitutes 3 comparifon be- tween the mythology of the Chinefe and that of the Hindoos ; of which the refult is, that the former people had an ancient fyftem of ceremonies and fuperftilion3 which has an apparent affinity with fome parts of the oldeft Indian worfiiip. " They believed in the agency of genii or tutelary iplrlts, pre fiding over the ftars and the clouds ; over lakes and rivers, mountains, valleys, and woods ; over certain regions and towns ; over all the elements, of whicli, li-je the Hindoos, they reckon- ed five ; and particularly over Jire, the n-.oft bi ill:, nit of them. To thofe deiiies they offered viilims on high places. And the follo.ving pafTage from one of their iacred books, inys Sir Wllh'am, is very much in the ftyle of the Brahmans : ' Even they who perform a facrifice with due reverence, cannot perfeftly affure themfelves that the divine fpirits accept their oblations; and far lefs can they, who sdore the gods with languor and ofcltancy, clearly perceive their facred illapfes.' Thefe (continues the Prefident) are iiiiperleft traces indeed, but they are traces of an affinity between the religion of Menu and that of the Chinas, whom he names among the apoftates from it ; and bcfides them, we dilcover many other very lingular marks of relation between the Ciiinefe and the old Hindoos. " This relation (he thinks) appears in the remark- able period of .(32,000, and the cycle of 60 years; in the predilection tor the myftical numbei nine; in many fimilar falls and great feftivals, efpecially at the i'olilices and equinoxes ; in the obfcquies, coufifting of rice and fruiis offered to the manes of their anccltors ; in the dread of dying chlldlefs, left fuch offerings fhould be intermitted ; and perhaps in their common abhorrence of rc^ objetls, which the Indians carried fo far, that Menu himfelf, where he allows a Brahman to trade, if he cannot otherwife fupport life, abiolnti;ly forbids his trading in any fort of red cloths, whether linen, or woollen, or made of woven bark. In a word, lays Sir William Jones, all the circuinflanccs which have been mentioned feem to prove (as far as fuJi i qiiefUui; ad- mits proof), that the Chinefe and Hindoos were origi- nally the fame people ; but having been feparated near 4000 years, they have retained few ftrong features of their ancient confanguity, efpecially as the Hindoos have preferved their old language and ritual, whih- the Chinefe very foon loft both ; and the Hindoos have 3 G conftantly China. CHI [41 conftamly intermarried among themfelves, wliile the Chinefe, by a mixture of Tartarian blood from tlie time of their firft ellablifhment, have at length formed a race diHiiiCl in appearance both from Indians and Tartars." Sir George fStaunton, who accompanied the Earl of Macartney on his embafiy to the ILmperor of China, does not indeed dircttly controvert this rcafoning ; but overlooking it altogether, gives to the Chinefe a much higher antiquity than Sir William Jones is inclined to allow them. Taking it for granted that tlieir cycle is t.lieir own, and that it is not the offspring of allronomi- cal fcience, but of repeated obfcrvations, he feems to ^ive implicit credit to thofe annals of the empire which almoU every other writer has confidcred as fabulous. "Next to the lludies which teach the economy of life, the Chinefe (fays lie) value moll the hillory o( the events of their own ccnmtry, which is, to them, the globe; and of the celeftial movements which they had an opportunity of obfcrving at the fame time." In re- gard to the former, he tells us, that "from about three centuries before the Chriftian era the tranfaflions of the Chinefe empire have been regularly, and without any intervening chafm, recorded both in official documents and by private contemporary writers. Nowhere had hiftory become fo much an objeA of public attention, and nowhere more the occupation of learned individuals. Every confiderable town throughout the empire was a kind of unjveriity, in which degrees were conferred on the proficient in the hillory and government of the ilate. Hiftorical works were multiplied throughout. The accounts of recent events were cxpofed to the correftion of the witneffes of the fafts, and compilations of former tranfaftions to the criticifms of rival writers." In re- gard to the latter, the movements of the heavenly bo- dies, he thinks that in no country are there llrongcrin- ducements or better opportunities to watch them than in China ; and hence he infers, that the cycle of fixty years is of Chinefe formation. " In a climate (fays he) favourable to aftronomy, the balance of hours beyond the number of days during which the lun appeared to return oppofite to, and to obicure, or to mix among the fame fixed ftai's, might be afcertained in a fhort time-; and occafioned the addition of a day to every fourth year, in order to maintain regularity in the computation of time, in regard to the return of the feafons ; but ma- ny ages mull have pad before a period could h.ive been difcovered, in which the unequal returns of the fun and moon were fo accurately adjuiled, that at its termina- tion the new and full moons (hould return, not only to the fame day, but within an hour and a half of the time they had happened, when the period commenced. The knowledge of fuch a period or cycle could be obtained only by a multiplicity of careful and accuiate obfcrva- tlons. Many revolutions of thofe great luULinavies mull have been completed, and numberlefs conjunftions have pad over, before their returns could be afcertained to happen in the fame day, at the end of nineteen years. The fmall diiference of time between the returning pe- riods of this cycle, was partly Itflened by the interven- tion of another of 60 years, or of 720 revolutions of the moon, which, with the fettled intercalation of 22 luna- tions, were at lull fuppofed to bring a perleft coinci- dence of the relative pofitions of the fun and moon : but even according to this period, every new year was made conftantly to recede, in a very fmall degree, which 8 ] CHI the Chinefe corrcfled afterwards from time to time, ( This cycle anfwercd a double purpofe, one as an era for '"" chronological reckoning, and the other as a regulating period for a luni-folar year. Each year of the cycle is dillinguiihed by the union of two charadters, taken from (uch an arrangement of an unequal number of words placed in oppofite columns, that the fame two charac- ters cannot be found again together for fixty years. The firll column contains a feries often words, tiie other twelve ; which lull are, in faft, the fame that denote the twelve hours or divilions of the day, each being double the European hour. The firft word or chnratltr of the firll feries or column of ten words, joined to the firll word of the fecond feries or column of twelve, marks the firft year of the cycle ; and fo on until the firll feries is exhaufted, when the eleventh word of the fecond feries, combined with the firft of the firft fe- ries, marks the eleventh year of the cycle ; and the twelfth or laft of the fecond ieries, joined with the fe- cond of the firft ieries, ferves for denoting the twelfth year. The third of the firft feries becomes united in regular progrefllon with the firft of the fecond feries, to mark the thirteenth year ; and proceeding by this rule, the firft charadler in the firft and in the fecond feries can- not come again together for fixty years, or until the firft year of the fecond cycle. The Chriftian year 1797 anfwers to the 54th year of the 60th Chinefe cy- cle, which afcertains its commencement to have been 2277 years before the birth of Chrift ; unlefs it be fup- pofed that the official records and public annals of the - empire, which bear teftimony to it, fhould all be falfi- fied, and that the cycle when firft ellablifhed (hould have been aiitidated ; which is indeed as little probable as that the period, lor example, of the Olympiads Ihould be afl'erled to have commenced many ages prior to the firft Olympic games." This is a very pofitive decifion againft the opinion of a man whole talenti and knowledge of oriental learning were fuch as to give to his opinions on fuch iubjefts the greatcll weight. If the ilatements and reafoiiings of Sir George Staunton be accurate, the Chinele em- pire mnft have fubtifted at leaft 3000 years before the Chriftian era ; for he fays exprefsly, that many ages muft have elajiied before the commencement ot that cycle, which, according to him, commenced 2277 years before the birth of Chrift. But furely Confucius was as well acquainted with the ancient annals of his own country, and the credibility which is due to them, as any man of the prefent age, whether Chinefe or Euro- pean ; and we have fecn, that he coiifidered none of them as authentic which relate events previous to the I ith century before our era. Even this is by much too early a period at which to rely upon them with impli- cit confidence, if it be true, as Sir Geoi-ge informs us,. that the tranfadtioas of the empire have been regularly recorded only from about three centuries before the birth of Chrift. With refpedl to the cycle, there is every probability that it was derived from India, where we know that aftronomy has been cultivated as a icience from time immemorial, and where, we have fhewn in another place, that the commencement of the cycle was atlually antedated (fee Philosophy, n'' g.Encycl.) We have therefore no hefitation in preferring Sir William Jones's opinion of the origin of the Chinefe empire to Sir George Staunton's; not merely becaufe we believe the hi'n. C H I [ 41 Chin*, the former of thefe gentlemen to have been more con- — ^' verfaiit than the latter -.vith Chinei't htcrature, but be- caufe we think liis reai'oning more i.onlillcnt with itltlt, and his concluiion move confoiidnt to that oiithne of chronology, which, as he obfervcs, has been fo correctly traced for the lall 20CO years, lliat we iniill be hardy fcipties to call it in qiieflion. There is another point very nearly related indeed to this, about whicli thcfe two learned men likcvvile dilfer. Sir George Staunton informs us, that " no ac- counts of a general deluge are mentioned in Chinefe hil- tory." Sir William Jones, on the other hand, in the difcourfe already quoted, fays, " I may afTure you, af- ter full inquiry and confideration, that tlie Chinefe, like the Hindoos, believe this earth to have been wholly co- vered with water, wliieli, in works of undilputed au- thenticify, they deferibe -asjlwiviii^^ uLunclniiily, thenfuL- JiJing, and fcparaliiig liie higher fimn ihc Id'wer ogc y mankind." To which of thefe iiiitiiors (hall we give credit ? The high antiquity which bir George Siaun- ton afTigiis to the Chinefe empire, rendered it neceilary for the perfons from whom he drew his information to get quit by any means of an univerlal deluge. The fyftem of Sir William Jones left him at liberty to admit or rejett that event according to evidence ; and in ad- dition to the authentic records to whicii he appeals, he quotes a mythological fable of the Chinefe, and another of the Hindoos, which, though he lays not upon them any great ftrefs, appear to us, when compared together, not only to corroborate his opinion refpecung the de- fcent of the Chinefe, but likewlfc to fiiew that both they and the Hiirdoos have prelerved a traditionary ac- count of the deluge very limilar to that which is given by Mofes. The Chinefe table is this : " The mother of FoHi was the daitghier of Hcwom, lurnanied i^/oizyfr- ioving ; and as the nympli was walking alone on the briirk of a river w/th a fimilar name, (Ire found herfe'if on a fudden encircled with a rainbow ; loorr aitcr which (he became pregnant, and at the end oi twelve years was delivered of a fon, radiant as herfcif, who, among other titles, had that of Sui, or the Star 0/ ibe Tear." In the mythological fyftem of the Hindoos, " the nymph RoHiNi, who prefides over the fourth lunar manlion, was the favour-ite miftrefs of Soma, or the Moon, among whofe numerous epithets we ilnd CumuJanayaca, or de- lighting in a fpecies of 'water-Jlotuer that blolfoms at night. The ollspriug of RonrNi and Soma was Bud- HA, r-egent of a planet ; and he married Ila, whofe fa- ther was prefcrvcd in a miraculous ark from an uni- verfal deluge." The learned prefideiit (hews, that, ac- cording to the Brahams, the Chineie defceadcd Irom BuDA ; and he mentions a divine perfonage connefted with the Chinefe account of the birth of Fo-Hi, whole name was Kiu-vA. But if all thefe circumllances be laid together, it will appear, we think, pretty evident, that the two ancient natrons have prefcrved the fame tradition of an univerfal deluge, and that the Chinefe RAINBOW and Niu-vA, with the Indian ark, point to the flood of Noah. To Sir William Jones's derivation of the Chinefe from the Hindoos, the ftate of their written language may occur as an objeftion ; for iince it is certain that alphabetical charafters were in ufe among the Hindoos before the per-iod at which he places the emigration of the Chinas, how, it may be aflced, came thefe people to ] € H I drop the mode of writing pradlifed by their anccftors, Clii.is. and to adopt another fovery inconvenient as that which * the Chinefe have ufcd from the foundation of their cui- pire ? Tire torce of this oLjcdtion, however, will vanilli, when it is remembered tliat the Chimis were of the mi- litary call ; that they had gradually abandoned the 01- diiidiices of the VeJa, and were in conlequtnee degia- ded ; aud that they laiiibkd from their irutive country in imall bodies. We do not know that the military cail among the Hindoos was ever niuch devoted to letters ; there is the greatcrl reafon to believe that a degi'ade-«l call would negleft them ; and it is certain that Inrali bodies of men, wandering in defeits, would have tlitir time and their attention comj^letely occupied in provi- ding for the day that was paffing over them. That the Chinas (liould have foi'gotten the alphabetical charac- ters of the Hindoos, is therefoi'e fo far irom being an ohjeiStion to Sir William Jones's accoui.t of their de- feerit from that people, that it is the natural coiiftqiiencc of tire manner in which he fays they rambled from Hiil- doltan to the northern provinces of what now confti- tutes the Chinefe empii'C. Of the origin of the charafters which are ufed by this Ihigular people, the iiluftrious prefrdent of the Ah- atic Society gives the following account from a Chinefe writer named Li Yang Ping. " The earlleft of them were nothing more than tlia outlines of vifrble objects, earthly and celellial ; but as things merely iiitelledtual could not be cxprelftd by thofe (igures, the gramma- rians of China contrived to reprefent the various opci'a- tions of the mirid by metaphors drawn from the pi'o- duftions of natu^'e. 'I'lius the idea of rouglrnefs and of rotundity, of motion and reft, were conveyed to the eye by iigns repreieiiling a mountain, the (Ivy, a I'iver, and the earth. The (igures oi the fun, the ir.oori, ard (he liars, differently combined, ilood for fmoothnefs and fpleiidour, for any tiling artfully wrought, or v/oven with delicate woiknianfiup. E.\tenrion, growth, in- cr"eale, and many other qualities, werx" painted in cha- -radters taken from the clouds, from the iirmamcnt, and from the vegetable part of the creation. The diflerent ways of moving, agility and (lownefs, idienefs and di- ligence, were expreflcd by various iiifetls, birds, iiflies, and quadrupeds. In this manner palTions and fentiments were traced by the pencil, and ideas not fubjcft to any fciife were exhibited to the light ; until by degrees new combinations were invented, new exprclTrons added, the characters deviated imperceptibly from their primi- tive fhape, and the Chinefe language became not only clear and forcible, but rich and elegant in the higheil degree*." ^ _ * ^f.^tlc Of this language, both as it is fpoken and 'wntitn, Rpf ear cbes. Sir George Staunton has given an account fo clear and vol ii. Me- fcientific, that it will undoubtedly' place him high among""''' '3- the moll eminent philologifts of the iStli century. As there is nothing relating to the Chinefe more wonder- ful than their language, which is very little iMidcrdood in Europe, we (hall lay before our readers a pretty co- pious abftradl of what he fays on the fubjeft, referring them for further information to his account of Lord Macartney's Embaffy to China. " In the Chinefe tongue (fays Sir George) the founds of feveral letters in moll alphabets are utterly unknown, and the organs of a native advanced in life cannot pronounce them. In endeavouring to utter the 3 G 2 founds CHI [ 420 ] . ^. ^ ^ China, founds of B, D, R, and X, for inftance, he fiiblUtutes has arifcn, according to him, from the finguhr habits < ' 'fome other founds to which the fame organ has been of the people; for though their common tongue be fij accuftomed ; L for R, and, as we liavc reafon to think nw/ically accented as to form a kind of recitative, yet it from fome cxprefTions of Sir Wilh'am Jones's, F for B. wants thofe grammatical accents without which all hu- The nice diftindions between the tones and accents of man tongues would appear monofyllabic. Thus Aniila, words nearly refembling each other in foiind, but vary- with an accent on the firft fyllable, means, in the San China. ing much in fenfe, require a nicety of ear to diihnguilh, and of vocal powers to render them exaftly. Synony- mous words are therefore frequently introduced in Chi- nefe dialogue to prevent any doubt about the intended fenfe ; and if in an intricate difcuffion any uncertainty ftioiild ftill remain as to the meaning of a particular ex- preffion, recourfe is had to the ultimate criterion of tra- cing with the finger in the air, or otherwlfe, the form of the charadter, and thus afcertaining at once which was meant to be exprefied. In a Chinefe fentence there is no marked diftinftion of fubftantives, adjeftives, or verbs ; nor any accordance of gender, number, and cafe. A very few particles denote the paft, the pre- fent, and the future ; nor are thofe auxiliaries employ- fcrit language, immeafurable, and the natives of Bengal pronounce it Omito ; but when the religion of Buddha, the fon of Maya, was carried into China, the people of that country, unable to pronounce the name of their new god, called him Foe, the fon of Mo-ye. ; and di- vided his epithet Am'ita into three fyllables Om ITO, annexing to them certain ideas of their own, and ex- prefling them in writing by three diftin£l fynibols. Hence it is that they have clipped their language into monofyllables, even when the ideas expred'ed by there, and the written fymbols for thofe ideas, are very com- plex." " In the Chinefe language Sir George Staunton in- forms us, .that there is a certain order, or fettled lyntax. ed when the intended time may be otherwife inferred in the fucceffion of words in the fame fentence ; a fuc ceffion fixed by cullom, differently in different langua- ges, but founded on no rule or natural order of ideas, as has been fometimes fiippofed ; for though a fentence confills of feveral ideas, to be rendered by feveral words, thefe ideas all exift and are conneded together in the fame inilant ; forming a pidure or image, every part of which is conceived at once. The formation of Chinefe fcntences is often the fimpleft and moft artlefs poflible, and fuch as may naturally have occurred at the origin of fociety. To interrogate, for example, is often at lead A finffle fyllable always expreffes a complete idea. Each to require the folution of a queftion, whether the fub- fyllable may be founded by an European confonant pre- jeft of doubt be in a particular way or the contrary ; ceding a vowel, fometimes followed by a liquid. Such and accordingly a Chuiefe mquirmg about his friends order of words prevents tlie harOmefs of fucceeding health, will fometimes fay, hou, poo hou ? The literal fonants founding ill together ; and renders the Ian- meaning of which words is, " well, not well ?" A fimple as foft and harmonious as the Italian is felt to chavadfr repeated ftands fometimes for more than one with certainty. A Chinefe who means to declare his intention of departing to-morrow, never fays that he ■will depart to-morrow ; becaufe the expreifion of the morrow is fufficient to afcertain that his departure mull be future. The plural number is marked by the addi- tion of a word, without which the fingular always is im- plied. Neither the memory nor the organs of fpeech are hurthened with the pronunciation of more founds to exprefs ideas than are abfolutely neceffary to mark their difference. The language is entirely monofyllabic. an con guage „- — be, from the rarity of confonants (id the frequency of its vowel terminations. " The names or founds, by which men may be firlt fuppofed to have diih'nguifhed other animals, when oc- cafion offered to defignate them in their abfcnce, were attempts at an imitation of the founds peculiar to thofe beings ; and ftill, in Chinefe, the name, for example, of a cat', is a pretty near refcmblance of its ufual cry. _ It occurred as naturally to endeavour, in fpeaking, to imi- tate the voice, if prafticable, as it was in writing to fketch a rude figure of the objiit of defcription. It is obfervable, that the radical words of moft languages, feparated from the fervile letters which mark their in- fleftions, according to their conjugations or declenfions, are monofyllabic. A part of each radical word is re- tained in compofitlon to denote the meaning and etymo- logy of the compound, which thus becomes poly fy lia- ble ; but the Chinefe grammarians, aware of the iucon- veni'ence refulting from the length and complication of founds, confined all their words, however fignificant of combined ideas, to fingle founds ; and retained only in writing, fome part at leaft of the form of each charac- ter denoting a fimple idea, in the compound charafters conveying complex ideas." This is a very plaufible, and perhaps the true, ac- count of the monofyllabic form of the Chinefe language ; but it is proper to ftate the different account which is given of this peculiarity by Sir William Jones. " It of the objeds which fingly it denotes, and fometimes for a coUcdive quantity of the fame thing. The cha- rader of moo fingly is a tree, repeated is a thicket, and tripled is a foreft. " In Chinefe there are fcarcely fifteen hundred dif- tind founds. In the written language there are at leaft eighty thoufand charaders or different forms of letters, which number divided by the firft gives neai-Iy fifty fenfes or charaders upon an average to every found expreffed ; a difproportion, however, that gives more the appearance than the reality of equivocation and un- certainty to the oral language of the Chinefe. " The charaders of the Chinefe language were ori- ginally traced, in moft inftances, with a view to exprefs either real images, or the allegorical figns of ideas : a circle, for example, for the fun, and a crefcent for the moon. A man was reprefentcd by an ered figure, with lines to mark the extremities. It was evident that the difficulty and tcdioufnefs of imitation will have occa- fioned foon a change to traits more fimple and more quickly traced. Of the entire figure of a man, little more than the lower extremities only continue to be drawn, by two lines forming an angle with each other. A faint refemblance, in fome few inftances, ftill remains of the original forms in the prefent hieroglyphic charac- ters ; and the gradation of their changes is traced in feveral Chinefe books. Not above half a dozen of the prefent charaders conSft each of a fingle line ; but moil of C H I [ 42^ T C H I China, of them coiifift of many, and a ftw of fo many as feventy ""■V~~" different ftvokes. The form of tliofe charai'iers has not been fo flux as the found of words, as appears in the in- llante of alnioft all the countries bordering on the Chi- iiefe Sea or Eaftern Afia, where the Chinefe written, but not the oral language, is underftood; in like man- ner, as one form of Arabic figures to denote numbers, and one fct of notes for mufic, are uniform and intel- ligible throughout Europe, notwithftanding the variety ot its hmguages. - " A certain order cr connection is to be perceived in the arrangtinent of the written characters of the Chi- nefe ; as if it had been formed originally upon a fyttem to take place at once, a. id not grown up, as other lan- guages, by flow and diilant intervals. Upwards of two hundred charafters, generally conlilling each of a few lines or ftrokes, are made to mark the principal objefts of nature, foniewhat in the manner of Bidiop Wilkin's divifions, in- his ingenious book on the fubjc6l of uni- verfal language, or real charafter. Thefe may be con- fidered as the genera or roots of language, in which every other word or fpecies, in a fyilematic fenfe, is re- ferred to its proper genus. The heart is a genus, of which the reprefentalion of a oirve line approaches fomevvhat to the form of the objeft ; and the fpecies referable to it include all the fentinients, paffions, and affedions, that agitate the human bread. Each fpecies is accompanied by fome mark denoting the genus or heart. Under the genus hand are arranged moll trades and manual exercifes. Under the genus wortl every fort of fpeech, ftudy, writing, underftanding, and de- bate. A horizontal line marks a unit; eroded by an- other line it Hands for ten, as it does in every nation which repeats the units after that number. The five elements, of which the Chinefe fuppofe all bodies in nature to be compounded, form fo many genera, each of which comprehends a great number of fpecies under it. As in every compound character or fpecies, the abridged mark of the genus is difcernible by a ftudent of that language, in a little time he is enabled to con- fult the Chinefe diftionary, in which the compound cha- radlers or fpecies are arranged under their proper gene- ra. The charafters of thefe genera are placed at the beginning of the diiilionary, in an order which, like that of the alphabet, is invariable, and foon becomes fa- miliar to the learner. The fpecies under each genus follow each other, according to the number of ilrokes of which each confills, independently of the one or few which ferve to point out tlie genus. Tlie fpecies want- ed is thus foon found out. Its meaning and pronuncia- tion are given through other words in common ufe; the firll of which denotes its fignifioation and the other its found. When no one common word is found to render exaftly the fame found, it is commiuiicated by two words with marks, to inform the inquirer that the con. fonant of the ftrft word and the vowel of the fccond join- ed together form the precife found wanted. " The compofition of many of the Chinefe charac- ters often difplays confiderable ingenuity, and ferves al- io to give an infight into the opinions and manners of the people. The charafler expreflive of happinefs in- cludes abridged marks of land, the fource of their phy- fical, and of children that of their moral, enjoyments. This charafter, embellifhed in a variety of ways, is hung up almoft in every houfe. Sometimes written by the hand of the emperor, it is feiit by him is a compliment, Ch ina, which is very highly prized, and luch as he w.is plealed • to fend to tiie cmbaflador. " Upon tlie formation, changes, and allufions of compound charafters, the Chinefe have publifticd many thoufand volumes of philulugical learning. Nowhere does criticifm more abound, or is more Itrift. The in- troduftion or alteration of a character is a ferious un- dertaking, and feldom fails to meet with oppofition. The mod ancient writings of the Chinefe are ftill clafli- cal amongd them. '1 he language feenis in no inftance to have been derived from or mixed with any other. The written feenis to have followed the oral language foon after the men who fpoke it were formed into a re- gular focicty. I'hongh it is likely thiit all hieroglyphi- cal languages were originally founded on the principles of imitation, yet in the gradual progrefs towards arbi- trary forms and louiids, it is prob;;ble that every fociety deviated from the originals in a different n-ianner from the others ; and thus for every independent fociety there arofe a feparate hieroglyphic language. As foon as a communication took place between any two of them, each would hear names and founds not common to both ; each reciprocally would mark down fucli names in the founds of its own chara<5lcrs, bearing, 33 hieroglyphics, a different fenfe. In that inftance, con- fequently, thofe charafters ceafe to be hieroglyphics, and were merely marks of found. If the foreign lounds could not be expreflcd but by the ufe of a part of two hieroglyphics, in the manner mentioned to be ufed fome- times in Chinefe dictionaries, the two marks joined to- gether become in facl a f) liable. If a frequent inter- courfe ffiould take place between communities fpeaking different languages, the neccffity of ufiiig hieroglyphics merely as marks of found would frequently recur. Tli^i practice would lead imperceptibly to the difcovery that, with a few hicrogl)phics, every found of the foreign language might be exprcffed ; and the hicrdglyphics which anfweied bell this purpolc, either as to exaAnefs of found or fmiplicity of form, would be fclefted for this particular ufe; and lerving as fo many letters, would form ill fafl together what is called an alphabet. TKus, the paflage from hieroglyphic to alphabeiic writing may naturally be traced, without the neceffity of having ' recourfe to divine iiidruClion, as fome learned men have conjeAured, on the ground that the art of writing by an alphabet is too refined and artificial for untutored reafon.' " The Chinefe printed charaflcr"is the fame as is ufed in moft manufcripts, and is chicfiy formed of llraight lines in angular politions, as moft letters are in Eaftern tongues, elpecially the Sanfcrit; the charafters of which, in fome inllauccs, admit of additions to their original iorm, producing a modification of the fenfe. A running hand is ufed by the Chinefe only on trivial occafions, or for private notes, or for the eafe and ex- pedition of the writer ; and differs from the other as much as an European manufcript does from print. There are books^ with alternate columns of both kinds of writing for their mutual explanation to a learner. " The principal difficulty in the ftudy of Chinefe wri- tings arifes from the general exclufion of the auxiliary particles of colloquial language, that fix the relation be* tween indeclinable words, fuch as are all thofe of the Chinefe language. The judgment mull be conftantly exercifed. C H I [ 422 ] C H I China, exercifed by the ftudent, to fupply the abfence of fuch "~~v affiftaiice. That judgment muft be guided by attention to the manncns, culloms, laws, and opinions of tlie Clil- nefe, and to the events and local circumftances of the country, to which the allufions of language perpetually refer. If it in general be true, that a language is difli- cult to be underllood in proportion to the diftance of the country where it is fpokcii, and that of him who endeavours to acquire it, becaufe in that proportion the -dUufions to which language has continually recourfe are lefs known to the learner, lome idea may be concei- ved of the obftacles which an European may expeft to meet in reading Chinefe, not only from the remotcnefs of fituation, but from the difference between him and the native of China in all other refpefts. The Chinefe charadters are in fa£l flictches or abridged figures, and a fentence is often a ftring of metaphors. The diffe- rent rehitlons of life are not marked by arbitrary founds, fimply conveying the idea of fuch connedtion ; but the -qualities naturally expefted to arife wit of fuch relations become frequently the name by which they are refpeclive- ly known. Kindred, for example, of every degree is thus dillinguilhed with a minutenefsuii known in ether langua- ges That of China has diflinft charafters for every modi- fication known by them of objefts in the phyfical and in- telleftual world. Abflracl terms are no otherwife exprcf- fed by the Chinefe than by applying to each the name of the moil prominent objefts to which it might be applied, wlu'ch is likewife indeed generally the cafe of other lan- guages. Among the Latins the abflratl idea of viitue, for example, was exprcffed under the name of valour or flrength (^villus), being the quality moft elleemed a- mong them, as filial piety is confidered to be in China. Ths words of an alphabetic language being formed of different coinbinations of letters or elemental parts, each with a diflinft found and name, whoever knows and combines thtfe together, may read the words without the leall knowledge of their meaning ; not lo hierogly- phic lai'.guagc, in which each charafler has indeed a found annexed to it, but which bears no certain relation to the unnamed lines or llrokes of which it is compo- fed. Such chara&er is fludied and beil learned by be- coming acquainted with the idea attached to it ; and a diftionary of hieroglyphics is lefs a vocabulary of the terms of one language with the correfpondent terms in another, than an encyelupxdia containing explanations of the ideas themfelves reprefented by fuch hierogly- phics. In fuch fenfe only can the acquifition of Chi- nefe words be juffly faid to engrofs moll of the time of men of learning among them. Tlie knowledge of the fciences of the Chinefe, however imperfect, and of their mod extenllve literature, is certainly fufficient to oc- cupy the life of man. Enough, however, of the lan- guage is imperceptibly acquireii by every native, and may, with diligence, be acquired by fortigr.ers for the ordinary concerns of life ; and further improvements mufl depend on capacity and opportunity." Next to ih^ lingular ItriiAure of the oral and writ- ten language of the Chinefe, there is perhaps nothing in their hiftory more furprifing to a native of Europe than the number of the people, and the means by which they contrive to procure fubfiflence, without foreign trade, in a country lo crouded, and at the fame time not everywhere of a fertile foil. In the Encyclopsedia, the population of this vail empire is ftated, from M. Grofier, at 200 millions: but great as this la, when com- China, pared with the population of every other extenfive coun- *— nr~- try, it appears to be far fliort of the truth. Sir George Staunton has publiflred a ftateincnt, taken from one of the public offices in the capital, nnd given by a great and reipcftablc manderin to Lord Macartney, in which it is (hewn that China Proper contains not fewer than 3^3 millions of inhabitants. As the extent of the coun- try is 1,297,999 fquare miles, there are of cnuric very near 260 inhabitants to every fqi;;;re mile; and of tliefe miles a very confiderable proportion confifts of nothing but barren rocks. Tiiat this account is accurate there can be little dotibt ; for the extent of the pro\inces was afcertained by aflruuomical obfervations, as well as by admeafurement ; and the number of individuals is regu- larly taken in each divifion of a diftrift by a tything- man, or every tenth mailer of a family. Thefe returns are colledted by c.flictrs rcfident fo near as to be capable of corrcdling any grofs millake, and are all lodged In the great regifter of Pckin. For this excefiive population cur author fatisfaftorily accounts. Celibacy, fays he, is rare in China, even in the military profeffion ; the marriages are prolific as well as early, and the influence of tiie patriarclial fy- ilesii, to be explained afterwards, is fuch, that a man's children adds to his wealth. It is reckoned a difcredit to be without offspring; and they who have none adopt others, who become theirs excluflvely. In cafe of mar- riage, fhould a wife prove barren, a fecond may be ef- poulcd in the lifetime of the full. The opulent, as in mofl pans of tl-.e Eaft, are allowed, without reproach, to keep concubines, of v.'hom the children are confider- ed as being thofe of the legitimate wife, and partake in all the rights of legitimacy. " Accidents fometimes of e.-itiaordiaary drought, and fometimes of excelTive in- undations, occafionally produce famine in particular provinces, and fainine diieafe ; but there are few drains from moral caufcs either of emigration or foreign navi- gation. The number of manufactures, whofc occupa- tionf are not always favourable to health, whole con- flant confinement to particular fpots, and fometimes in a clofe or tainted atmofphere, mufl be injurious, and whofe refidence in towns expofcs them to irregularities, bears but a very fmall proportion to that of hufband- men in China. In general there feems to be no other bounds to Chinefe popiiloufnefs than thofe which the neceffity of fubfiflence may put to it. Thefe bounda- ries are certainly more enlarged than in other countries. The whole furlace of the empire is, with trifling excep- tions, dedicated to the proJudlion of food for man alone. I'here is no meadow, and very little paflure ; nor are fields cultivated In oats, beans, or turnips, for the fupport of cattle of any kind. Few parks or plea- fure grounds are feen, exccptliig thofe belonging to the emperor. Little land is taken up for roads, which are few and narrow, the chief communication being by wa- ter. There are no commons, or lands fuffered to lie wallc by the negleft, or the caprice, or for the fport of great proprietors. No arable land lies fallow. The foil, under a hot and fertihzing fun, yields annually, in mcfl inflances, double crops, in confequence of adapt- ing the culture to the foil, and of fupplying Its defefts by mixture with other earths, by manure, by irriga- tion, by careful and judicious induftry of every kind. The labour of man is little diverted from that induftry to C H I [ 4 Chin-!- to minifter to the luxiinVs of the opulent and power- — V ' ' ful) or ii] employments of no real life. Even tlie fiil- diers of the Chinefe army, except durmg the Ihort in- tervals of the guards which they are called to mount, or the exercifes. or other occafional fcrvices which they perform, are moftly employed in agriculture. Tlie quan- tity of fubfillence is increafed alfo, by converting more fpecies of animals and vegetables to that purpofe than is ufual iii other countries. And even in the ])rcparation of their food the Chinefe have economy and management." The government of Ciiina is defpotic; and It is a cu- rious fpedaole to behold fo large a proportion of the whole hunnn race, conneAed together in one great fy- llem of polity, fubinittiiig quietly, and through io con- fiderahle an extent of country, to one great fovercign ; and uniform in their huvs, their manners, and their lan- guage, but dlifering effeiuially in each of thefe refpefts from every other portion of mankind : and neither de- firous of communicating with nor for.ning any defigns againll the veli of the world. To produce fuch a phe- nomenon, many caufes muftbe conibi.ied ; but perha[)S the principal are to be found in the patriarchal fyftem already mentioned, in the laws and cufloms of the em- pire, and in the belief that the emperor is the vicege- rent of heaven, and guided In all his aftions by divine infpiration. The patriarchal fyilem Is founded upon that filial piety which the philofophers of China have uniformly reprefented as the greateft of human virtues. Thefe fagcs, while they fuccefsfuUy Inculcated this duty, have left parental afFettion to its own natural influence ; and hence In China parents are lefs frequently neglefted than infants are expofed. The laws of the empire, to cor- roborate the difpofition to fili.il obedience, furnifli an opportunity for punlfhing any breach of it, by leaving a man's offspring entirely within his own power: and hence it is, that with the poor, marriage, as we have faid, is a meafure of prudence ; becaufe the children, particularly the fons, are bound to maintain their pa- rents. A Chinefe dwelling is generally furroundcd by a wall fix or feven feet high. Within this inclolure a whole family, of three generations, with all their refpec- tlve wives and children, will frequently be found. One fmall room Is made to fcrve for the individuals of each branch of the family, fleeping In different beds, divided only by mats hanging from the ceiling. One common room Is ufed for eating. The prevalence of this cuftom, of retaining the feve- ral branches of a family under the fame roof, Is attend- ed with Important effefts. It renders the younger tem- perate and orderly in their conduft under the auhorlty and example of the older ;' and it enables the whole to fubfill, like foldlers in a mefs, with more economy and advantage. As the venerable patriarch of each habi- tation prefides over his deicendants with the authority of a maglitrate ; fo the different orders of magillrates are, in their different diftrltts and provinces, looked up to with the veneration due from children to their pa- rents, while the emperor is revered as the grand patri- arch of the whole empire. Another thing which contributes much to the per- manency of the government and the internal quiet of the empire is, that in China there is lefs inequality In the fortunes than in the conditions of men. The ancient 23 ] CHI annals of the empire teflify, that fo" along period of China, time, the earth, like the other elements of natuic, was '^~~ enjoyed by Its inhabitants alnoft in common. Their country was divided into fm;Jl equal dlllriift'; ; every dlftrict was cultivated conjointly by eight labouring fa- milies, which compofed each hamlet ; and they enjoyed all the profit of their labours, except a certain (hare of the produce referved for public expcnces. It is true, indeed, that after a revolution, dephred In all the Cninefe hiltories, which happened prior to the Chriftian era, the ufurper granted all the lands away to the part- ners of his viiloncs, leaving to the cnltivitors of the foil a fmall pittance only out of the revenue which it yielded. Property in l.md alfo became hereditary : but In procefs of time, the molt confiderable domains were fubdivldcd Into very moderate parcels by the fucceffive diftribution of the poffeffions of every father equally among all his fons ; the daughters beinj; always married without dower. It very rarely happened that there was but an only fon to enjoy the whole property of his deceafed parents ; and it could icarcely be increafed by collateral fuccelTion. From the operations of all thofe caufes, there was a conllant tendency to level wealth ; and few could fuc- ceed to fuch an accunuilatlon of It as to render them Independent of any efforts of their own for Its Increafe. Befides, wealth alone confers in China but little impor- tance, and no power ; nor Is property, without office, always perleflly fecure. There is no hereditary digni- ty, which might accompany, and give it pre- eminence and weight. The delegated authority of government often leans more heavily on the unproteftcd rich than on the poor, who are lefs objefts of temptation. And It Is a common remark among the Chinefe, that for- tunes, either by being parcelled out to many heirs, or by being loll in commercial fpeculatlons, gaming, or extravaga :ce, or extorted by oppreffive mandarines, fel- doni continue to be confiderable In the individuals of the lame family beyond the third generation. To afcend again the ladder of ambition, it Is ncteffary, by long and laborious ilnJy, to excel in the learning of the coun- try, which alone qualifies for pulilic employments. There are properly but three clalLs of men In China : men of letter;, from wliom the mandarines a.-e taken ; cultivators of the ground ; and mechanics, including merchants. In Pekni alone is conferred the higheil de- gree of literature upon thofe who, In public exanu'- nations, are found raoft able in the fclences of morality and government as taught In the ancient Chinefe wri- ters ; witii which ftiidies the hltfory of their country I« Intimately blended. Among fuch graduates all the ci- vil offices in the ftate are dillrlbuted by the emperor ; and they compofe all the great tribunals of the empire. The candidates for thofe degrees are inch as have fuc- ceeded In fimilar examinations in the principal city of each province. Thofe who have been chofen In the cities of the fecond order, or chief tf)wn of every dlf- trift in the province, are the candidates in the provin- cial capital. They who fail in the firft and fecond claffes have ftill a claim on fubordinate offices, propor- tioned to the clafs in which they had fucceeded. Ttiofe examinations are carried on with great folemnity, and apparent fairnefs. Military rank is likewife given to thofe who are found upon competition to excel in the military art, and in warlike extrclfes. This diftribution of CHI [42 China, of offices contributes greatly to the peace of the em- "~~* pire ; for the people cheerfully fubmit to the authority of thofe whom tlicy believe to he placed over them by merit alone, and love that conllitution which brings within tlie reach of the nieancll fiibjcft, who has talents and induftry, the hightil llation next to the fupreme. " The gi eat tribunals are fituated, for the fake of con- venience, near the fouthern gate of the imperial palace at Pekin. To them accounts of all the tranfaCtions of the empire are regularly tranlmitted. They are coun- cils of reference from the emperor, to whom tiiey report €very bufuiefs of moment, with the motives for the ad- vice which they offer on the occafion. There is a body of doftrine compofed from the writings of the earlicft. ages of the empire, confirmed by fubfequent lawgivers and fovereigns, and tranfmitted from age to age with increafing veneration, which ferves as rules to guide the judgment of thofe tribunals. This doflrine fcems, in- deed, founded on the broadeft bafis of univerfal juftice, and on the pured principles of humanity. " His imperial majefty generally conforms to the fug- geftions of thofe tribunals. One tribunal is dlrcited to confider the qualifications of tiie different mandarines for different offices, and to propofe their removal when found incapable or unjuft. One has for objeft the pre- fervation of the manners or morals of the empire, call- ed by Europeans the tribunal of ceremonies, which it re- gulates on the majiinij that exterior forms contribute not a little to prevent the breach of moral rules. Tire moll arduous and critical is the tribunal of cenfors ; taking into its confideration the effeft of fubfifting laws, the conduft of the other tribunals, of the princes and great officers of Hate, and even (jf the emperor himfelf. There are feveral fubordinate tribunals ; fuch as thofe of mathematics, of medicine, of public works, of litera- ture and hidory. The whole is a regular and confiifent fyftem, ellablilhed at a very early period, continued with little alterations through every dyiiailv, and re- vived after any interruption from the caprice or pafiions of particular princes. Whatever deviation has been made by the prefent family on the throne, arlfes from the admillion of as many Tartars as Chincfe into every tribunal." The opinions of the former are fuppofed al- ways to preponderate ; and many of thcin are indeed men of confiderable talents and ftrength of mind, as well as polilhed manners. They are, hovvever, in gene- ral, fitter for military than civil offices. The hardy edu- cation, the rough manners, the aClive fpirit, the v/an- derlng dlfpoiition, the looie piinciples, and the irregu- lar conduct, of the Tartar, fit him better for the pro- feffion, practice, and purluits of war, than the calm, re- gulated, and domeftic habits of the Chincfe. Warriors feem naturally the offspring of Twrtary, as literati are of China; and accordingly, the principal military com- mands are conferred on natives of the former country, as, with many exceptions indeed, the chief civil offices are on thofe of the latter. A military mandarin, who was much with Lord Ma- cartney, and was himfelf a dillinguiflied officer, affert- ed that, " Including Tartars, the total of the army in the pay of China amounted to 1,000,000 infantry and 800,000 cavalry. From the obfervatlons made by the embaffy in the courfe of their travels through the em- pire, of the garrifons in the cities of the feveral orders, aad of the military polls at fmall dillances from each 4 1 CHI other, there appeared nothing unlikely in the calculi; Chlfls. tion of the infantry ; but they met few cavalry. If the —— v— " number mentioned leally do exifl, a great proportion of them mull have been in Tartary, or on fome fcrvice di- flant from tlie route of the enibafly. " Of the troops, efpecially cavalry, a vafl number are Tartars, who have a higher pay than their Chinefe fel- low-foldiers. The principal officers of confidence in the army are Tartars alfo. None of either nation are received into the fervice but fuch as are healthy, (Irong, and fightly. The pay and allowances of a Chinefe horfeman are three Chinefe ounces, heavier than Euro- pean ounces, and three-tenths of an ounce, of filver, and fifteen meafures or rations (the weight not men- tioned) of rice every lunar month. A Tartar horfe- man, feven fimilar ounces of filver, and 20 meafures of rice for the fame period. A Chinefe foot foldler has one ounce and fix-tenths of an ounce of fiKer, and ten meafures of rice ; and a Tartar of the i'ame defcrlption has two ounces of filver and ten meafures of rice every lunar month. Tiie Emperor furnifhes the arms, ac- coutrements, and the upper garment, to all the foldiers. Befidc their ordinary pay and allowances, they alfo re- ceive donations from the Emperor on particular occa- fions ; as when they marry, and when they have male children born. On the death of their parents they ob- tain ' a gift of confolation ;' as do their families when the foldiers thcmfelves die. < " The public revenues of China Proper are faid to be little lefs than 200,oco,ooo of ounces of filver, which may i)e equal to about 66,000, coo of pounds flerling ; or about three times thofe of France before the late fubverfion. From the produce of the taxes all the ci- vil and military expenccs, and the incidental and extra- ordinary charj^es, are firtl paid upon the fpot out of the treafurles of the refpeftlve' provinces where fuch cxpences are incurred; and the remainder is remitted to the Imperial treafury at Pekin. This furplus amounted in the year 1792 to the fum of 36,614,^28 ounces of filver, or 12,204,776 pounds flerling, according to an account taken in round numbers. In cafe of infurrec- tions, or other occurrences requiring extraordinary cx- pences, they are generally levied by additional taxes on the provinces adjacent to the fcene of a6lion, or con- nefted with the occafion of tiie expence. " In the adminillration of the vail revenue of the ftate, the opportunities oi* committing abufes are not often neglecled; as may be inferred from the frequent confif- catlon to the Emperor in confequence of fuch tranfgref- fions. It is indeed affirmed, that much corruption and oppreffion prevail in moil of the public departments, by which confiderable fortunes are acquired, notwith- llandlng the modicity of the public falaries." With fuch a Handing army and fo vaft a revenue, it will no longer appear wonderful that one man fhould govern with defpotic fway even the immenfe multitude of people who inhabit the empire of China, efpecially trained up as thofe people are in habits of filial fubmif- fion to their fuperiors. But there are fome circumflan- ces in the fyltem of Chinefe policy, not yet mentioned, which contribute perhaps more than even thefe habits and that power to preferve the ftabillty of the govern- ment. The Emperor referves to himfelf alone the right of relieving the wants of the poor, produced by famine or any other unforefeen calamity. On fuch occafions he CHI [4 Cliliiu. hp aUvays comen forward, lie ordors tlic public gra- ■""v— iiavica to be opened ; remits the taxes to thole who are vilited with misfortune; affords afliihnce to enable them to retrieve their affairs; and appears to his fubjefts as flanding almoll in the place of Providence in their fa- vour. He is perfeftly aware by how much a itronger chain he thus maintaius his abfulute dominion, than the mere dread of punilliment would afford. The emperor, to whom the Britifh embaffy was fent, fliewed hirafelf fo jealous of retaining the exclulive privilege of bene- volence to his fubjefts, that he not only rejefted, but was offended at, a propotal once made to him by lomc confiderable merchants, to contribute towards the relief of a fufFering province ; whilft he fcrupled not, at the fame time, to accept the donation of a rich widow to- wards theexpences of a war in which he was engaged. This veneration, excited towards the emperor by his apparent benevolence, is increafed by an opinion zea- loufly inftilled into the people, that he has the faculty of predicting future events of the greatell importance. The Chinefe, given up to the dotages of judicial aftio- logy, are firmly perfuaded that eclipfts of the fun and moon have a powerful influence on the operations of nature and the tranfaftions of mankind ; and the pe- riods of their occurrence become, of courfe, objefts of attention and folicitude. The government of ttie coun- try, ever anxious to eflablifh its authority in the general opinion of its fuperior wildom and conflant care to*- the welfare of the people, employs the European milHon- aries at Pekln (for it is doubtful if any one of the na- tives has fo much foence) to calculate eclipfcs, and then announces them to the people with that iolemnity which is fitted to enfure veneration for the fuperintend- ing power whence fuch knowledge is immediately de- rived to them. Eclipfes of the fun, in particular, are confidered as omenous of fome general calamity ; and as great pains are taken to infpire them with a belief that their profperity is owing to the wildom and virtues of their fovereign, fo they are tempted to attribute to fome deficiency on his part whatever they think por- tentous. To this prejudice the emperor finds it pru- - dent to accommodate his conduct. He never ventures on any undertaking of importance at the approach of a folar eclipfe, but affefts to withdraw himfclf from the prelence ot his courtiers, to examine ftridfly into his late adminiftration of the empire, in order to correft any error, for the commilTion of which the eclipfe may hmve been an admonition. On thtfe occafions he in- vites his fubjefts togive him freely their advice: but it is plain that advice muft be offered with great deference to a being for whofe admonition the motions of the fun and moon are believed to be regulated ; and while fuch notions are implicitly admitted, the perfon of the Chi- nefe emperor, as well as his authority, mufl be looked upon by his fubjeds as fomething more than human. SuppL. Vol. I. Part II. 25 3 CHI This ij in t:\&. the cafe. He is not only approached in perfon witii tcftlmonies of the utmoft refpedt, but is adored when abfent with all the rites and ceremonies whii.h are ufed by the Chinefe in the worlhip of their divinities. On his birth-day, at the new and full moon, and piobably on other feflivals, all the mandarines re- lident in the neighbourhood of any of his numerous pa- laces aflfemble about noon, and repairing to tiie palace, folenmly proflrate thcmfelves uine times before the thror.e, their foreheads llrikiiig the floor each time ; whilft inceufe is burning on trlp(.ds on each fide of it, and offerings are made, on an alter before it, of tea and fruits to the fpirit of the abfent emperor. Over the throne are feen the Cliinefe characters of glory and per. feftlon ; and the name of the Deity is given to the em- peror, who is confidered by his votaries as polTefling in fome fenle the attribute of ubiquity. Mr Barrow, one of the gentlemen of the embalTy, was prefent at Tuc'ti- mln-yuen, one of tiie imperial palaces, when tliefe idola- trous rites of adoration were performed; and lie was af- fured that they took place on that d ly in ail parts of the empire, th^; proltraters being everywhere attentive to turn their faces towards the capital. That he who claims adoration in his abfeuce does not appear on his birth-day to receive the compliments of his fubjeds, will not furprilc the reader. The man- ner in which that fellival is celebrated at the palace, where the emperor happens to be refident, is thus de- fcribed by Sir George Staunton, who w-itne.Ted this more than augufl ceremony at the palace of Zhe-hal in Tartary. " The princes, tributaries, ambaffaJors, great officers of ftate, and principal mandarines, were afi'em- bled in a valt hall; and upon particular notice, were in- troduced into an inner building, bearing, at leaft, the femblance of a temple. It was chiefly furnifhed with great Inltruments of mufic, among whicli were fcts of cylindrical bells, fulpend-d in a line from ornamented frames of wood, and gradually diminiiliing in fize from one extremity to the other, and alio triangular pieces of metal arranged in the fame order as the bells. To the found of thefe inftruments a How and folemn hymn was fung by eunuchs, who had fuch a command of tlieir voices as to referable the effett of the mufical glalfcs at a dillance. The performers were directed, in gliding from one tone to another, by the llriking of a fhrill and fonorous cymbal ; and the judges of nuillc among the gentlemen of the embaffv were much pleated with their execution. The whole had indeed a grand eflTcd. During the performance, and at particular lignals, nine times repeated, all the perfons proltrated tliemfelves nine times, except the ambaffador and his fult, wlio made a profound obeifance (a). But he whom it was meant to honour, continued, as if it were in imitation of the Deity, invllible the whole time." That the awful imprellion meant to be made upon Chi- H the (a) The Chinefe court, which eonfiders all other fovereigns as fubordlnate to their own, exa£ts from foreign minlfters, as well as from natives of the empire, nine proftrations upon their firll introduAlon to the emperor. This demand was made, in the lafl century, of the Dutch, wno inftantly complied with it in hopes of obtainii.g in return fome lucrative advantages ; and the confequence was, that their amballador was treated with negleft, and difmiffed without promlfe of the fmalleft favour. It was likewife made of a Ruffian ambaffador in the pre- fent century ; but he would not complv with it, until a regular agrfjment was made for its return, on a like oc- cafion, to his own fovereign. Lord Macartney, who was repeatedly u-gpd to go through the fame abjeS cere- mony, difplayed fuch firmnefs and addrefs, that after much evalion it was at lafl announced to him, that his im- perial majefly would be fatisfied with the fame form of refpectful obedience that the Engllfh are in the habit of paying to their own fovereign ; and upon thefe lerme his lordfhlp w,as introduced and gracioufly received. C H I [ 426 1 C H I China, the minds of men by this apparent worfliip of a teilovv- ■~~V— ~ mortal might not be too quickly ellaccd, all fcencs of fport and gaiiity w ere poftponed to the next day, when a variety of enteitainmtnts was exhibited in the pre- fence of the emperor, furrounded by his court and tri- butary princes. ' Notwithftanding the general veneration of the Chi- iiefe for the perfon and government of their emperor, tlie mandarines afferted that a fed had for ages fubfifl- ed in the country, vvhofe chief principles were founded on an antipathy to monarcliy, and who nourirtied hopes of at laft fiibverting it. Their meetings were held in the ntiTioft fecrecy, and no man avowed any knowledge of tliem ; but a fort of inquifition was faid to be efta- blifhed in order to find them out, and they who were fufpeded of fucli fentiments were cut off, or himted out of fociety. Should the French declaration of the rights of man, which, through the zeal of its authors, has been tranflated into one of the languages of India, find its way into China (of which the court is faid to be much afraid), it would indeed be a powerful engine in the hands of this fccret fed to fap the foundations of the ancient government. The minds of many of the Chinefe are far from fatisfied with their condition, which lays both their perfons and their fortunes at the mercv of the mandarines. No private man in China is exempted from corporal punifhment, which luijy be inftantly in- flifted on him at the nod of a magiftrate; and when he has occafion to fpeak to a great mandarine, he is obhged, by the police of the country, to throw himfelf on his^ knees, and in that pofture to communicate his bufinefs. The mandarine himfelf, on the xither liand, lies under the hardship of being frequently refponfible for events which he could not controul. Upon the general prin. ciple that it is his duty to watch over the morals of the people, he is in many cafes conlidered as a criminal for not preventing crimes which he had not been able to prevent. The mandarines are thus aware of not being guaranteed by good conduA againft difgrace; and feel- ing the chagrin of infecurity, many of them muft doubt- lefs be ripe for a revolt. Fear may keep them quiet du- ring the reign of a fovercign pofiefled of abilities and vigi- lance ; but the maxims which regulate the imperial luc- eeffion are liich, that a firm confederacy could hardly - fail at the death of an emperor to introduce great changes into the conftitution. The throne of Ciiina is neither hereditary nor eleftlve. The choice of a fucceffor is left entirely to the reigning prince, who may exclude, as has been inftanced, even his own offspring and fami- ly. To prevent commotions and fraud, it is no un- common praftice for the emperor, during his lifetime, to declare his fucceffor ; fur when his fuccefGon is fet- tled by a written teftament, the throne is not always filled by him for whom it was dellined. The father of the emperor to whom the Britifh embaffy was fent, is faid to have obtained pofl'effion of the throne by fud- denly entering the palace in the laft moments of his predeceffor, and fubftituting his own name in a tefia- ment intended for the exaltation of another. To what has been faid in the Encyclopsedia of the re- ligion of the Chinefe, we have here very little to add. Various deities are worfhipped in the empire by very different rites and ceremonies ; but there is in China no ftate religion. None is paid, preferred, or encouraged by it. The emperor is of one faith j many of the man- darines of another ; and the maiority of th-e cornrr.on people of a third, which is that of Fo. The men of let- "" ters venerate rather than adore Confucius; and meet to honour and celebrate his memoiy in halls of a fimple but neat coi.flruttion. The numerous and lower clalTes of the people are Icfs able than inclined to contribute much towards the ereftion of large and. cofVIy edifices for pu- blic worfhip : their attention is almofl wholly engaged by their houfhoid gods ; for every houfe has its altar and its deities. " No people are, in faft, more fuperftitious than the common Chinefe. Beiide the habitual offices of devo- tion on the part of the priefts and females, tlie temples, are particularly frequented by the difciples of Fo pre- vioufly to any undertaken of importance ; whether to marry, or go a journey, or conclude a bargain, or change fituation, or for any other material event in life, it is necefTary firlt to confuit the fuperintendant deity. This is performed by various methods. Some place a • parcel of confecrated flicks, differently marked and numbered, which the confultant, kneeling before the altar, fliakes in a hollow bamboo, until one of tliem falls on the ground ; its mark is examined, and referred to a correipondent mark in a book %vhich the piieft holds- open, and fometlmes even it is written upon a fheet of; paper pafled upon the infide of the temple. Polygonal pieces of wood are by others thrown into the air. Each- fide has its particular mark ; the fide that is uppermoft when fallen on the floor is in like manner reientd to its correfpondent mark in the book or fheet of fate. If the firfl throw be favourable, the perfon who made- it proftrates himfelf in gratitude, and undertakes after- wards with confidence the bufinefs in agitation. But if the throw fliuuld be adverfe, he tries a fecond time, and the third throw determines, at any rate, the qucf- tion. In other refpefts, the people of the prefent day feem to pay little attention to their priefls. The temples are, however, always open for luch as choofe to confuit the decrees of heaven. They return thanks, when the oracle proves propitious to their wifhes. Yet- they oftener caft lots to know the iffue of a projccled: enterprife than fup])licate for its being favourable: and their worfhip conhfls more in thankfgiving than in prayer. " The Chinefe are feldom faid to carry the objefts to be obtained by their devotion beyond the benefits of this life. Yet the religion of Fo profeffes the doctrine of the tranfmigration of fouls, and promiles happinefs to the people on conditions, which were no doubt ori- ginally intended to confifl in the performance of moral duties ; but in heu of which are too frequently fubfti- tuted thofe of c-ontributions towards the ereftion or re- pair of temples, the maintenance of priefts, and a flrlft attention to particular obfervances. The negleft of tliefe is announced as punlihable by the fouls of the dcr faulters pafhng into the bodies of the meanetl animals, in whom the f'ufferings are to be propo.'tioned to the tranfgreflions committed in the human form." Though the Chinefe artifls are very ingenious Es mere workmen, there is hardly any thing which de- fcrves the name of fcience in the whole empire. S» little is the ftudy of mathematics cultivated, that there are few fliopkeepers in China who can perform the or- dinary operations of arithmetic ; but call up their ac- counts by means of an inflrument called /man/iaw (See SWAM- Chl. C H I [ 427 ] C H I Chi-11. SwANPAv, Encyei). Though the compofition of ,i;uii. """V——' powder was certainly known in China much e.iiher than in Europe, and thouj!;h the Chiiiefe had employed it from the beginning in blading rocks, and in making a vaft variety of five-works ; yet Sir George Staunton fetms convinced, that they newr thought of tlie inven- tion of guns till they were taught by the Europeans to introduce them into their armies. Tlie ftite of phyfic in this vail country is extremely low, being nowhere taught in p\ibiic ichools or colleges. *' A young man who willies to become a phyficlan, has no other way of acquiring medical knowledge than by engaging hinilelf to fome praftitloncr as an apprentice. He has thus the opportunity of feeing his mailer's pratliL-e, of viliting his patients with him, and of learn- ing fuch parts of his knowledge and lecrets as the other choofes to communicate to him. The emoluments of the profefGon feldom exceed the fl 5, 6, 7, 8, 9, 10, 20, 30, 40, i;o, 60, 70, 80, 90, &c. Of courfe, thofe weights which (land re- lated to each other in the proportion of 6 to 7, 7 to 8, 8 to 9, 9 to 10, differ fo little in fize, that it would be impofTible to diftinguiih them witliout the help of the charatlcrs which are engraven upon the face. This is confefTedly a defeft in the fyftem. Of the four diffe- rent feries exhibited to the fociety, the higheil bears in China the name of kin, and is nearly of equal value \vith a pound avoirdupois. The kin contains ten times the number of units of the next inferior weight, which the Chinefe denominate hang or loam, and which the Europeans call tufl, Uuile, or Chinefe ounce. This ounce is divided into ten t/'.tn, which anfwers nearly to our drachm. The tfien is again fubdivided into ten fm. The Chinefe extend the decimal fubdivifion of their weights confiderably farther. They have diftinft names, which are all monofjllabic, for nine feries below the fen. Suppofing the kin to Hand for unity, they have, 000000000000 8 ] C H O I, - 1* 000000000 c:U;>c:c--OOc -^ o £ — The Chinefe weights, compared with the greateft precifion, and with the help of the bed inftruments, Kear the following proportion to our weights : The kin is equal to 1 pound iz ounces 2 drachms 24 grains; the leang i ounce J drachm 60 grains; the tfien 70 grains ts ; the fen 7 grains -rig. Coufequently the lad of this feries, the fun, amounts to no more than o grains 000CO00070S. CmNhSE Wheel is an engine employed in the province of Kiang-fee, and probably through the whole empire, for raifing water from rivers to irrigate plantations of fugar canes, on a fandy foil, confiderably elevated above the level of the river. By Sir George Staunton, who iays that it is ingenious in its contrivance, cheap in its materials, eafy in its operation, and effcdtual to its pur- pofe, it is thus defcribed : " Two hard wood-pofls or uprights are firmly fixed in the bed of the river, in a line perpendicular to its bank. Thefe polls fupport the axis, about ten feet in length, of a large and durable wheel, confifling of two unequal rims, the diameter of one of which, clofcil to the bank, being about fifteen inches ihorter than that of the outer rim ; but both dipping in the ftream, while the oppofite fegment of the wheel rifes above the eleva- ted bank. This double wheel is connefted with the axis, and is fupported by 16 or 18 fpokes obliquely in- ferted near each extremity of the axis, and crofTing each other at about two-thirds of their length. They are there flrengthened by a concentric circle, and fallened afterwards to the rims : the fpokes inferted in the in- terior extremity of the axis reaching the outer rim, and thofe proceeding from the exterior extremity of the fame axis, reaching the inner and fmaller rim. Between the rims and the croffing of the fpokes is woven a kind of clofe bafliet-work, ferving as laddie-boards or floats, which meeting fucceflively the current of the (Iream, obey its impulfe, and turn round the wheel. To both its rims are attached fmall tubes or Ipouts of wood, with an inclination of about 25 degrees to the horizon, or to the axis of the -vhtel. The tubes are clofed at their outer extrenn'ty, and open at the oppofite end. By this pofition the tubes, which happen iu the motion of the wheel to be in the flreani with their mouths or open ends uppcrmoll, fill with water. As that fegment of the wheel rifes, the mouths of the tubes attacli to H, alter their relative inclination, but not fo much as to let their contents flow out till fuch fegment of the wheel becomes the top. The mouths of thofe tubes are then relatively depreffed, and pour the water into a wide trough placed on polls, from whence it is conveyed as may be wanted among the canes. " The only materials employed in the conllrudlion of this water-wheel, except the nave or axis, and the polls on which it refts, are afforded by the bamboo. The rims, the fpokes, the laddie-boards or floats, and the tubes or fpouts, and even the cords, are made of entire lengths, or fingle joints, or large pieces, or thin flices, of the bamboo. Neither nails, nor pins, nor fcrews, nor any kind of metal, enters into its conflruc- tion. The parts are bound together firmly by cord- age, alfo of flit bamboo. Thus, at a very trifling ex- pence, is conflrufted a machine which, without labour or attendance, will furnifh, from a confiderable depth, a refervoir with a conftant fupply of water adequate to every agricultural purpofe. " Thefe wheels are from 20 to 40 feet in diameter, according to the height of the bank and confequent elevation to which the water is to be raifed. Such a wheel is capable of fuflaining with eafe 20 tubes or fpouts, of the length of four feet, and diameter two inches in the clear. The contents of fuch a tube would be equal to fix-tenths of a gallon, and a periphery of 20 tubes, twelve gallons. A ilream of a moderate ve- locity would be fufficient to turn the wheel at the rate of four revolutions in one minute, by which would be lifted 48 gallons of water in that fliort period ; in one hour, 2'6ho gallons ; and 69120 gallons, or upwards of 300 tons of water, in a day." Sir George, who faw this wheel in motion, thinks it preferable in many refpefts to any machine yet in ufe for limilar purpofcs. He obferves, that, while it ap- proaches near to the Perlian wheel, of which a defcrip- tion and figure is given in the article Hydrostatics, Encycl. it is more fimple than that wheel in its con- trivance, and much lefs expeniive. This is indeed true ; but the fimpleft engine of the kind, and therefore the btfl that has yet been invented, is perhaps that which is employed to throw water into the mofs of Blair Drummond in Perthfhire. See Moss, Encycl. CHOPINE, Chop?ine, or Chopeene, a high fhoe, or rather chig, worn 2CO years ago by the Italians. Tom Coryat, in his Crudities 161 1. p. 262, calls them chapineys, and gives the following account of them ; "There is one thing uled of the Venetian women, and feme others dwelling in the cities and towns fubjedl to the figniory of Venice, that is not to be obferved, I thinke, amongfl any other women in Chriflendome, which is fo common in Venice, that no women whatfo- ever goeth without it, either iu her houTe er abroad. Chinefe, Chopine. C H R ChronoUv gic.-:l. Chowdry a thing made of wood and covered luith leather of fundry colors, fame ivil/j luhite, fume redde, fame yellow. It is callt-d a cliajjiney, which they wear under their Jhoes. ^ Many of them are cun'oiilly painted ; fome alfo of tliem 1 have feeii faiily gilt ; lo uncomely a thiiiy;, in my opinion, that it is pitty this fooh'fli cuftom is not cltane banilhed and exterminated out of the citie. There ,ire many of thefe chapineys of a great height, even half a yard l>igh, which maketh many of their women that are very Jhort feeme much taller than the tailed women we have in England. Alfo I have heard it obferved among them, that by how much the nobler a woman is, by fo inuch the higher are her chapineys. All their gentle- women, and moll of their wives and widowes that are of any wealth, are afliiled eyther by men or women when they walke abroad, to the end they may not fall. They are borne up mod commonly by the left arme, otherwife they might quickly take a fall." CHOWDRY, in Bengal, the pofleffor of feveral Taloois. It is alfo ufed as fynonymous with Talookdar, anciently a cojleclor. See Talook in this Supplement. CHRISOM was not, as is faid in the Encyclopedia, a face-cloth or piece of linen laid over the child's head tvhen itwas baptized ; but it was a white vefture or garment, which, immediately after it was baptifed, the prieft put upon it, faying, " Take this white vefture as a token of the innocency, which, by God's grace in this holy facrament of baptifm, is given unto thee, and for a fign whereby thou art admoniilied, fo long as thou livcft, to give thyfclf to innocence of living, that after this tranfitory life thou mayeft. be partaker of life ever- lading. Amen." As foon as the pried had pronounced thefe words, he anointed the infant upon the head, faying, " Al- mighty-.God, the Father of our Lord Jefus Chi-ift, who hath regenerated thee by water and the Holy Ghoil, and hath given unto thee the remifilon of all thy fins ; he vouchfafe to anoint thte with the un(3.ion of his Holy Spirit, and bring thee to the inheritance of ever- lafting life. Amen." It was from this anointing or chrifm that the white garment got the name of chrifom, which, after being v?orn a few days, was offered to the pried to be kept in the church or vedrv, in order to be produced as evidence againd the perfon whofe chrifom it was, Ihould he afterwards deny the faith in which he had been baptized. Thefe ceremonies were retained, for fome time after the reformation, in the church of England, which ordered the mother of the child (if the child was then alive) to offer, v^hen die was churched, {.he chrifom and other accudomed offerings. If the child died be- fore its mother was churched, the chrifom was not gi- ven to the pried, but employed as a fhroud, in which the body was buried ; and hence it is that chrifoms are now enumerated, mod abfurdly indeed, in the weekly bills of mortality. We (ay abfurdly ; becaufe children who die unb-iptized are called chrifoms, though the chri- fom, when it was ufed, was never put on till baptifm. See Whitbf on the Book of Common Prayer, Isfc. CHRONOLOGICAL characteks are charafters by which times are dldinguiihed. Of thefe fome are natural or aftronomical ; others, artificial or hidorical. The natural charadters are fuch as deper.d on tlie mo- tions of the liars or luminaries, as ulipfes, foljlices, equi- r 429 ] C H R noxes, the different afpelts of the planets, &c. The ar- tificial charaders are tliofe that have been invented and edabliflicd by men ; as the folar cycle, the Ivnar cycle, &c. Hillorical chronological ebaraders are thofe fup- v ported by the tellimuny of hilloriaus, uben they fix the dates ui certain events to certain y«r/W.f. Hutlon's Ma- thematical l)iflion,iry. CHRONOSCOPE, a word fometimes ufed to de- note a pendulum or machine to meafure time. CHUCKIAH, in Bengal, the jurifdiclion of a Fa. gedar. See Fogedar in this Supplement. CHURCH is a word which has many different fig- nifications, all fufficiently explained in the Eiicyclopje- dia Britannica, where there is likewife given a concife hi/lory of the Chridian church (fee History, Sett, ii.), defective, indeed, but perhaps not more fo than was to be expeftt d from the limits of the work and the extent of the fubjett;. Of the eonditution of the primitive and apodolical chtirch, no man can have a corredt notion who has not taken the trouble to confult the primitive and apodoli- cal writers ; for, as we have elfewhere obferved, all mo- dern compilers of eccleiiadical hiftory are more or lefs prejudiced in behalf of the particular church to which they belong, and wred the language of the original writers fo as to make them bear witiiefs to the antiqui- ty of modes of faith and ecclcf-ajUcal polity, which are not perhaps a hundred years oM. On this account we fhall not here attempt to correft what we really think the midakes of him who compiled the fedtion of ecclefiadical hiftory in the Encyclopadia. Moflieim and Sir Peter King, whom he feems to have implicitly followed, were indeed great men ; and it would be folly to deny that the Hiftory oi the former, and the Inquiry of the latter into the Conflitiilion of the Primitive Ckurch, are works of learning and ingenuity 5 but it is not perhaps too much to fay, that both au- thors wrote under the influence of prejudice. Our read- ers will difcover how clofcly either the one or the other has adhered to truth, by ftudying the eccleiiadical wri- ters of the fiid four centuries. Such a dudy will make • them acquainted with the dottrines, difcipline, ,Tnd wor- fliip of the church before it was incorporated with the date ; and we know not that kind of knowledge which ' i'i of more importance to the divine, however much it may be defpifed in tills age of alfedcd fcience and real • ignorance. Of the priiicipal churches at prefent exiding, a pretty full account is given in the Encyclopsdia, either under their d'fferent denominations, or under the titles of thofe tenets by which they are chiefly didinguiflied ; ib that from that Work alone a reader may form a tolerably accurate notion of the faith, worfhip, eonditution, and dilcipline of the church of Rome, the churches of Eng- land and Scotland, the Lutheran and Calviniltical- churches on the continent of Europe, as well as of the various iects which have arifen in thefe kingdoms du- ring the courfe of the lad and prefent centuries. There is, however, one church which boads of a very high an- tiquity, and is certainly f])rcad over a larger extent of country than all the other churches that we have men- tioned, of which the account given in the Encyclopse- dia is exceedingly defective. Our readers will perceive that the church to which we allude is The^ Chreno- Icoie II Church. C 11 u [ 430 ] C H U I ;C church. Church. The Greek Chvkch, which comprehends in its bo- ' fom (a) a coiiridciahle part of Greece, the Grecian The Greek '<1^*' VValhichia, Moilavia, Egypt, Ab; (linia, Nubia, Lybia, Arabia, Mt-fopotamia, Syria, Cilicia, and Pale- iline, which are all under tlie jurildittion of the patri- archs of Coullaiitinople, Alexandria. Antioch, and Jc- rufalem. If to tlicfc we add the whole of the Ruflian empire in Europe, great part of Siberia in Alia, Al- tracan, Cafan, and Georgia — it will be evident that the Greek church has a wider extent of territory than the Latin, with all the branches which have fprung from it ; and that it is with great impropriety that the church of Rome is called by her members the catholic or uni-- verfal church. That in thefe widely diilant countries the profeifors of Chriitianity are agreed in every minute article of belief, it would l)e rafli to alTert ; but there is certainly fuch an agreement among them with relpecl both to faith and to difcipliue, that they mutually hold communion with each other, and are in fadl but one chuich. As the Greek church has no public or eftablifhed articles, like thole of the churches of England and Scotland, we can collect what is its dodrine only from its creeds, from the councils whofe decrees it receives (b), from the different offices in i's liturgies, and from the catechifms which it authorifes to be taught. " The dodrine of the Trinity, and the articles of the Niceiie arid Athanafian creeds, are received by the Greeks in common witli other Chrillians. In one particular, in- deed, they differ from the other churches of Europe, whether Romilh or reformed. They believe that the Holy Spirit proceeds from the father only, and not from the Father and the Son ; and in defence of this opinion ihey appeal to eccle!>alticai hiftory, the ads of councils, the writings of the fathers, ancient maim- fcripts, and efptcially to a copy of the creed of Con- ftantinople, engraven on'two tables of filver, and hung up in the church of St Peter at Rome by order of Eeo III. Of the Nicene or Conllantiuopolitan creed, there- fore, as it is received by them, the eighth article tuns in thefe words, ' I believe in the Holy Ghoft, the Lord and Giver of life, who proceedeth from the Fa- ^ Dalh- THER, and with the Father and the Son together is tojv'j C""- worihipped and glorified :' And the correfponding ar- fanim.pU, .^j j- ^^^ AthamifiaQ ci-fed is of courfe, «' The Holy jHnctent and ^ , ^ , „ - 1 j ^ j Modirn, Ghoftisof the Father, neither made, nor created, nor and Kings begotten, but proceeding -j-." Jtitci andCi- Tfioiiah the bilfiops and clergy of the Greek church ••""""'"■^' abhor th'e ufe of images, which they pretend to be one It admits of caufe of their feparation from the fee of Rome, they ad- pSaures mit into their churches the pidures of famts to inilruft, they fay, th.e ignorant, and to animate the devotion of others.' I'his pradice they conhder as by no means The faith of that church. bur not of graven image;. contrary to the fecond commandment of the decalogue, Ohin-rh. which, according to them, prohibits only the worlhip- ' v~~ ping of fuch idols as the Gentiles believed to be gods ; whereas their pidures, being ufcd merely as remembran- cers of Chrill and the faints, have written on each of them the name of the perfon whom it \i meant to re- prefent. Dr King aflures us that the more learned of the Ruffian clergy would willingly allow no reprelenta- tion whatever of God the Father ; and that, during the reign of Peter tlie Great, the fynod not only cenlured the ufe of fuch pidures in churches, but petitioned the emperor that they might be everywhere taken down. Peter, however, though he fully -concurred in opinion with the fynod, thought this a meafure for which the minds of his fnbjeds were not ripe, and dreaded, that if carried into execution it would occafion a general in- furredion. Such pidures, therefore, though not more impious than abfurd, aie rtill in ufe; and in many churches, as well ancient as modern, the iigure of Da- niel's Atic'ient of Diiys, together with that of Chrill and a dove, are paiiited in one group to lignify the Holy Trinity. Nay, when our author was in St Peterfburg, not thirty years ago, there was in the ch\nch of St Ni- cholas the pidure of an old man holding a globe, and furrounded with angels, on which God the Father was intcribed ; and we have not heard that the pidure has been fince taken down. In the Greek as well as in the Roman church, the i, vocatioi invocation of faints is pra6f ifed, but they are not invo- of faints, ked in either as deities, but merely as interceffors with the Supreme God, " it being more modeft (fay the Greeks), as well as more available, to apply to them to intercede with God, than to addrels ourfelves immedi- ately to the Ahnighty." Plauhble as this reafoning may at firft fight appear, it afcribcs to the faints the di- vine attribute of ubiquity, and is likewife in divtd con- tradidion to the dotlrine of St Paul, who hath taught us, that as " there is one God, fo there is but one me- diator between God and man, the man Chrill Jel'us." j The Greek church, at the celebration of the Lord's P.- ayers for Supper, commemorates the faithful departed, and even "'' dead, prays. for the remiflion of their lins ; but flie allows not of purgatory, nor pretends to .determine dogmatically concerning the Hale or condition of depaited fouls. She mull, however, believe that no final judgment is paffed upon the great body of mankind (c) till the conlummatiou of all things, otherwile fuch prayer* could not be oflered without abfurdity ; and in this part of her dodrine (lie is certainly countenanced by all the writeis of the primitive church, if not by fome paffages of the facred fcriptures *. The pradice of praying for.^ Math. the dead is loudly condemned in every Protellaut coun-xxv. 19, 20, try, and yet there is noChrillian wlio does ni.it in efted — 31 — 34- pray ^ '^™- >• ^^' ____^___— ^___^-_ iv. 8. (a) King's Riles and Ceremonies of the Greek CAaz-cA— Bruce's Travels to the Source of the Nile — and Lobo's Voyage to Ah\[finta. . , , . . . , 'm r 1 Tb) in the'Greek church i^t^iw general councils are -received, and nine provincial ones. i lie leven general councils are, i. The council of Nice, held in the year 325, uilder Conftantiue. 2. The firft council of Conftan- tinople, held A. U. 381, under Theodofius the Great. 3. The council of Ephefua, A. D. 431, in the reign of The'odolius iVIinor. 4. The council of Calcedon, A. D. 4JI, in the reign of'Marcian. 5. The fecond coun- cil ofConllantinople, A. D. 5^3, in the reign of Juftinian. 6. The third council of Conllantinople in Trull, A. D. 680, in the reign of Co'nllantine Pagonatui. 7. The fecond council of Nice, A. D. 787. Vc) We fay the great body of mankind, becaufe fhe doubtlcfs believes that Enoch, Ellas, and thoffi faints who rofe with our'Saviuur, have been already judged, and now enjoy their rewvi in heaven. C H U [ 43r ] C H U Chnrvh. Grants no jiidulgeB- cics. Predeftina- tion. Seven fa- (ramciits. 9 Daily fer- vice of the church, pray for Iiis departed friends. This may appear a pa- ' radox, but it is an obvious and a certain truth ; tor where is the man who believes in a general judgment, and does not nulfh that his deccafed wife, or parent, or child, or friend, " may find mercy of the Lord in that day ?" Such a wifli is the eflence of a prayer ; which confills not of the founds in which our fentiments/are cloathed, but in the afpivations of a dtvout heart. Supererogation, with its confequent indulgencies and difpcnfations, which were once fo profitable, and after- wards fo fatal to the infcrelts of the court of Rome, are utterly difnllowed in the Greek church, which likewilc lays no claim to the charaitcr of iniallibility. She is indeed, like fome othtr churches, very inconfillent on this lail topic ; for wliilit ibe pretends not to an abfo- lute exemption from error, her clergy fctm to coulidcr their own particular mode of worlhip as that which alone is acceptable to Goil. Predellination is a dogma of the Greek church, and a very prevailing opinion amongd the people (jt RiilHa; " and 1 mult do the jullice (fays Dr King) to thole who have written upon it, efpecially the lattll autliors of that country, to fay that they have treated it, as de- pending on the attribute of prefcience in the divine na- ture, with a much better kind of logic than that with which fuch points are generally difculTcd." As our author has not given us the realoning of the Rnflian doctors on this difficult fubjcfl, we cannot lia/ard any opinion of our own on the foundnefs of their logic ; but from the ftate of fcience in that vail empire, as it was reprefented to us by an abler judge than he, we doubt of its being entitled to the praife which he be- llows on it. (See Russia, n" \o^. Ericjcl.) In the Greek church there are {evenfacrametits; or, as they are there termed, myjieries, viz. haptifm ; the chr/fm, or baptifmal undtion ; the euchanj} ; canfejfion ; ordina- tion ; marriage; and the myftcry of the holy oil, or eii- cheliiion. By the Greeks a myllery is delined to be " a ceremony or aft appointed by God, in which God givetli or iignifieth his grace ; and ot the feventh which they celebrate, four are to be received by all Chrillians, viz. baplifm, the baptifmal iitiSwn, the cucharij], and con- fejjion. Of thefe, baplifm and the euchariji are deemed the ct.ief ; and of the other three, none, not even the euchclaion, is confidertd as obligatory upon all. With refpttl to baptifm,we know not that they hold any peculiar opinions. They confider it indeed as fo abfolutely neceflary to falvation, that in cafes of extre- mity, when a pried or deacon cannot be had, it may be adminiftered by a midwife or any other perfon, and is not to be repeated on any occafion wha-tever. Li this opinion, as well as in the praftice founded on it, they are in perfect harmony with the church of Rome, which, as every perfon knows, has for many ages al- lowed the validity of laybaptifm in cafes of necefnty. The Portuguele Jefuits, who in the laft century vifited AbylTmia in the capacity of miflionaries, have maintain- ed that, once every year, all grown people are in that country baptifed : but Mr Bruce has (liewn, by the moft incontrovertible evidence, that this was a mere fiftion, invented to throw odium upon what the church of Rome calls the eaftern chifm, and abhors perhaps more than pagan ifm it felt. The daily fervice of the Qreek church is fo long and fo complicated, that it is impoffible for us to give an adequado account of it without fwelling this article far Church, beyond its due proportion. Of this the reader will be " convinced, when he is informed that the fcveral books [jj,jjj.^[g containing the church fervice for all the days in the nJ tcJioui. year, amount to more than twenty volumes in folio, belides one large volume called the regulation, which contains the directions how the rell are to be ufed. The four golpcls make one volume by themfelves ; and whenever tlie golpel is read in any fervice, the dea- con exclaims ; " \Vifdoii'., Hand up. Let us hear the holy golpel." The prieil then faith, "The IcfTon from the gofpel according to St Maiihew, i.t Mark, &c." The deacon fays again, " Let \is itand." The choir, at the beginning and end of llie gofpel, always fays, " Glory be to thee, O Lord, glory be to thee." From tlic old tellameiit and the epilUes extracts only arc uled in the fervice ; and when they are to be read, the dea- con calld out, " Attend." The fervice of this church as it now ftands, and was at fird drawn up in writing, is calculated for the ufe of monalleries ; and when it was afterwards applied to pa- rochial chuiches, many of the offices or forms, which were coinpoftd for different hours of the day and night, were uled as one fervice, without the flighttil altera- tion being made ti.- avoid repetitions. So.^lething of this kind has taken place in the church of England, where the matins, tlic litany, and the communion, which were formerly three ('.illinft fci-vices, read at dif- ferent times of the day, are now run into one fervice ; which by thofe not accullomed to it is therefore deem- ed long, as well as deformed by needlefs repetitions,. The fervice of every day, whether it has a vigil or g^ginj j^ not, begins in the evening of what we would call the the even* preceding day, as among the Jews; and for the fame '"g« reafon, becaufe it is faid in the Mofaic account of the creation, that "the eve:^ing and the morning were the firft day." The fcveral feivices, according to the ori. ginal or monkiili inllitulicn, are, I. The vefpers, which ufed to be ctk-bratcd ft little before fun-ftt ; 2. The af- ter-vefpers, anfvvericg to the coniplitorium of the Latia church, which ufed to be celebrated after the monks had fupped, and before they went to bed ; 3. The me- foityeSicon, or midnight fervice ; 4. The matins at break of day, anfwering to the laadcs of the Romitk church ; 5. 'i^he. firjl hour of prayer, or prima, at fun-rife; 6. The third-hour, or lertia, at the third hour ot the day ; ^. 'Y\\tftxth hour, or fexta, at noon ; 8. The ninth hour, or nana, in the atternoon at the ninth hour of the day. Thefe are called the canonical hours ; but it is to be obferved, that the ajter-vcfpcrs. were not added till a late period, before which the reafon afiigned for the number of fervices being (even, was, that David faith, " Seven times a-day will I praife thee." When all the pfalms and hymns were fung, thcie daily fervices could not pofubly have been performed in lefb than twelve or fourteen hoars. In the church of RulTia, and probably in other branches of the Greek church, there are at prefent but three fervices in the day: the ninth hour, the vefperj, and the after-vefpers making one ; the mfonye^icon, the matins, and prima, another ; and the third and Jiath hour, with the communion, the lail. In all the fervices, except the communion, prayers and praifes are offered to fome faint ; and to the Virgin Mary, almoll as often as to God ; and in fome of the fervices, after every fiiort prayer uttered by the. deacon or the prieft, the choir C'hnrth. Mode of a.lminiller- jiigbaftifni C H U [43 clioir chaunts " Lord have mercy upon us," thirty, forty, or fifiy times, lixccflivrly. Tlumgh tlic number of forvices is the fame every dav, the fervices thcmiclves are conftantly varying in fome pavticiiLir or other, as there is not a day which, in the Greek church, is not cither a fail or a fellival. Befuk's the f.ints, whofe feftivals are marked in the ca- Itndar, and who are fo very nunerous that there are m6re than one for every day in the year, there are other faints and feltivals, to which fome portion of the fervice for evei-y day of the week is appropriated. Thus, Sunday js dedi.Mted to the refurreftion: Monday, to the angels; Tuefday, to St John Daptill; Wcdnei'Ja) , to the Virgin !ind the crofs; Thurfday, to the apolUes; Friday, to the pafllon of Chrifl ; and Saturday, to the laints and mar- tyrs. For thefe days there are particular hymns and fervices, in two volumes folio, to which there is a fup- plemcnt containing icrvices for the faints and feftivals, as they occur in the calendar thro\ighout the year. Thefe different fervices are mixed together, and adjuft- ed by the dirertions contained in the book of regulation ; and it is the difiiculty of this adjullment which makes the public worfiiip of the Greek church fo very intricate, that, as was faid of the fervice of the Engliili church be- fore the ReformatloH, " there is more bufmcfs to find out what (hould be read, than to read it when found out." We have obferved, that the Greeks have no peculiar opinions rcfpefting the nature of baptifm ; but the rites and ceremonies with which that ordinance is admini- ftercd will appear to our unlearned readers very extra- ordinary. On the day that a woman is delivered, the prieft goes to the houfe, and ufes a form of prayer for her and for the child. On the eighth day the child fliould be regularly carried to the church, where the prieft having ligned it with the fign of the crofs on the forehead, on the mouth, and on the breaft, offers up for it a prayer, in which he firft gives it a name, com- monly the name of the faint for that day in the calen- dar ; he then takes it from the midwife, and Handing before the pifture of the blclTed Virgin, he makes the fign of the crofs vTith the infant, uttering a kind of liymn in honour of the Virgin and of Simeon, who held in his bofom the Saviour of our fouls. He then difniifics the company with an exhortation not to delay the baptifmg of the infant, (hould it appear in danger of death before the regular time for its baptifm. On the fortieth day after her delivery, the mother fliould attend the church to be purified, and carry the child again to be pvefented, the perfon who is to be fponfor being prefent. Upon their arrival at the church door, the prieft utters fome pious exclamations ; and then, the mother holding the child in her arms and bowing down her head, he makes the fign of the crofs upon her and the child, and laying his hand upon its head, he prays that the woman may be cleanfed from every fin and from every defilement, and that the child rnay be fandified and endued with undcrftanding, with wifdom, and with gentlencfs of manners. He then figns it again, and again prays for it, for its parents, and for its fponfur ; after which, if it has been privately baptifed, he takes it in his arms, and makes with it the 2 ] C H U fign of the crofs before the door of the church, fayinjj, Churen. " N. N. the lervant of Gud, enters into the churcli, in *""->—« the name of tiie Father, and of the Son, and of the Holy Ghoft, now and for ever, even unto ages of ages. .A.men." H." then carries tlie child into the church,- faying, "he Ihttll go into thine h.oufe, and Ihall worfhip toward thy hcrly temple ;" and advancing into the mid- dle of the church, he fays, " In the midft of thy church fliall lie praife thee." I'hen, if the child be a boy, he carries hi:n within the rails of the altar ; but if a girl, only to the door, and fays " Nunc dimitlis (d);" after which he delivers it to the fpoulor, who makes three reverences, and retires. This is called the prefentation of the child in the temple, and can only he performed after it has been baptized. In the detail we have given, we have fnppo- fed that it was baptized privately before the purifica- tion of the mother, which is now indeed conimoidy the cafe. Such baptifm, hcvvever, is not regular, being al- lowed only in cafes of neceffity ; and when it has not taken place, the mother and child are dilniiffed as foon as {he is purified, and return at fome other time, not fixed, in order that the child may be publicly baptized. Previous to baptifm, the child, though not two months old, muft be folemnly initiated into the church as a catechumen (See Catechumen, EncycL) By thofe whofe religion is a reafonable fervice, fuch initia- tion of an infant will be confidered as a very idle cere- mony; and the rites with which it is performed are not well calculated to give it even a fictitious uiiportance. At the door of the church the prieil unties the girdle of the infant ; takes off all his clothes but one loole gai"- ment ; turns him towards the eall, with his head unco- vered, his feet naked, and his hands held down ; blows thrice in his face ; figns him thrice with the fign of the crofs on the forehead and on the breaft, and lays his hand upon his head, praying that his " amietit error may be put away from him ; that his heart may be fil- led with faith, hope, and charity ; and that he may walk in the ways of God's commandments." The prieft then four times cxorclfes the infant, commanding Satan, in the firft exorcifm, to " tremble, depart, and flee from Chrift's creature, nor dare to return again, nor dare to lurk concealed within him, or to meet him, or to meditate againft him, either in the evening or the morning, at midnight or at noon-day." In the lafl exorcifm he blows thrice upon the child's mouth, upon his forehead, and upon his breaft ; faying, each time, •' Drive away from him every evil and unclean Ipirit that lurks in him, and hath made itfelf a neft in his heart." The child is now becom.e a catechumen, and, being turned t*) the weft, uncovered, without ihoes, and his hands lifted up, the prieft repeatedly afks him if he renounces and has renounced the Devil and all his works ? and receiving from the fponfor the proper anfwer, he fays, " Blow and fpit upon him ;" and having blown and fpit upon the catechumen, he turns him to the eaft, and holding down his hands, afks him repeatedly if he be joined to Chrift, and if he believes in him ? The ca- techumen or his fponfor replies to each queftion, that he is, and has been, joined to Chrift ; and as a proof of his (0) We quote the words of Dr King. Greek tiymns have Latin defignations ? I3 it pofllbk that in the Greek church Latin hymn« are ufed, or that C H U t 433 3 C H U 'ch. his faith he repeats, from beginning to end, the NIcene end, the 3:d Pfalm; he then puts upon the baptized Church, /~*~' cived. After a repetition of the formerly repeated perfoii a white garment; faying, " N the fervaiit o{^~~~y~~— quellions and anfwers, the prieft prays that the cate- God is clothed with the garment of rightcoufnefs, in chumen may be called to God's holy fantlification, and the name of the Father, and of the Son, and of the receive the g'ace of God's holy baptifm. Holy Gholl, now and for ever, even unto ages of ages Baptifm may be celebrated immediately after the (e)." He then prays that lie may be delivered from candidate has been made a catechumen, or on any fub- the evil one, and all his inlidious fnares ; that he may fcqnent day at no great dillance. In the lirft part of be confirmeil in the true faith; and that he may pre- the form there is not much that is fiiigiilar, or with ferve iiis fonl in purity and rightcoufnefs: and proceeds which every Icholar is not acquainted. After praying immediately to anoint him with the ffuiy Chrlfm. ij that the water may be fandlihed, in terms differing little This chrifm is a very diii'erent thing from the oilThebap. from thofe which are ufed in the moll refpeAable Pro- with which he was anointed previous to baptifm, and •''^","' teftant churches, the priell dips his fingers in it, figns which was ufed in the confecration of the baptifmal it thrice with the (ign of the crofs ; and then blowing water. It can be prepared only by a bifhop, and only upon it, fays three times, " Let every adverfe power be on one day in the year, 'uiz,. Thurfday in Fafiion-wtek; confounded under the fign of the crofs." He then fo- and as the anointing with it is fubllituted in place of IcMinly exorcifes it of the dsmon of darknefs and all the apoftolical rite of laying on hands, called confirma- evil fpirits; and prays, that " the pcrfon to be haptifed tlon in the wellern churches, great quantities of it are therein may put off the old man, which is corrupt after of courfe prepared at once, and dillributed through the the lull of fraud, and may put on the new man after different churches of each diocefe. The chriim confilLs the image of Him that made him. After this, he of the following ingredients, which in different prupor- blows thrice into a veffel of oil of olives held by the tions are all boiled together, and afterwards foleuuiiy deacon, figns it thrice with the fign of the crofs ; and confecrated by the bilhop : Fine oil (we fuppofe of prays fervently, that it may " become to thofe who are olives), white wine, ftyrax calamita(F), palm dew, anointed with faith, and are partakers thereof, the unc- rofe-flowers, black palm-gum, Bahl-g\im, marjoram, tion of incorruption, the armour of rightcoufnefs, the thick and thin oil of nutmegs in vei y difiercnt quanti- renewing of foul and body, for turning aiide all niachi- ties, oil of cinnamon, oil of cloves, lignum Rhodii, oil nations of the devil, and for deliverance from all evil." of oranges, oil of marjoram, oil of laveiidar, oil of rofe- He then lings allelujah thrice with the people, and reary, effence of rofemary, cedar, blsck balfdin ol Pe- pours the oil on the top of the water ; and making rn, fandarac, whitcft inaftic, and Venice turpentine. three crofTes with it, fays aloud, " Bleffed be God, who With this holy miKture the baptized perfon is anointed, enlightcneth and fandifieth every man that cometh in- the prieft making with it the lign of the crofs on his to the world, now and forever, even unto ages of ages." forehead, on his eyes, his n<,llrils, his mouth, bo h ears, The perfon to be baptized is then prefented ; and the his bread, his hands, and his feet; faying at each part, prieft, taking fome of the oil with two fingers, and ma- " The feal of the gift of the Holy Gholl. Amen." king the lign of the crofs on his forehead, on his breaft, Then with the fponfor and the child he goes thrice and bctviixt his ftioulders, fays, " N the fervant of God round the font, turning from the right to the left; the is anointed with the oil of gladnefs, in the name of the choir, in the mean time, finging, " As many ot you as Father, and of the Son, and of the Holy Gholl, now are baptized unto Chrift have put on Chrift, allelujah." end forever, even unto ages of ages. Amen." He then Seven days after this ceremony is pertornied, the figns him on the breaft and the middle of the back, child is again brought to the church ; when the prieft, faying, " For the healing of his foul and body ;" then after praying for him, unties his girdle and linen clothes, on the ears, faying, " For hearing the faith ;" then wafhes him with clean water, and, fprinkling him, fays, on the palms of the hands, faying, " Thy hands have " Thou hall been juftified, enlightened, ianttified in made me and faftiioned me ;" then on the feet, " That the name of our I^ord Jefus Chrift, and with the Spirit he may walk in the way of thy commandments." Af- of our God." Then taking a new fponge moiftened ter the whole body is thus anointed, the prieft baptizes with water, he wafhes his face, breaft, &c.; laying, him, ufing the trine immerfion ; which is unqueftionably " Thou haft been baptized, enlightened, anointed, ianc- the moft primitive manner. He takes the child in his tified, waftied, in the name of the Father, and of the Son, arms, and holding him upright with his face towards the and of the Holy Ghoft, now and for ever, even unto ages eaft, he fays, " N the fervant of God is baptized [dip- of ages. Amen." 14 ping him the Jirjl time), in the name of the Father, A- Tl»e laft ceremony appended to baptifm is that of The ton- men ; in the name of the -Son {^dipping him again). A- the tonfure, or Ihaving the head of the child in thefure. men ; and of the Holy Ghoft [dipping him the third form of the crofs. At what time this rite crept into nW), Amen, now and for ever, even unto ages of ages, the church it would not be eafy to difcover. Some Amen." After the baptifm, the prieft wipes his hands, think it received its origin from the religious ceremo- and with the people fings thrice, from beginning to nies of the Heathen, who certainly rounded the corners SUPPL.VOL. I. Partn. 3 I of (e) The reader will perceive, that many of thefe rites and ceremonies are common to the Greek church and the church of Rome in the celebration of the facrament of baptifm. (f) We quote the words of Dr King, taking it for granted that our readers will pardon our not giving our- felves much trouble to difcover, on the prefent occafion, what particular fpecies or variety of the ftorax he mean* by this defignation. See Styrax, Encycl. C H U [ 434 ] Chorch. of their heads, and marred their beards, at a very early clare his ge: ■"^ ' period, in honour of their idols (See Theology, n"^ I 55. Encyc!,) ; and fome pious, but foolifh Chrilliaiis, efteemed it highly commendable to transfer to the true God that vvorthip, in a different form, which had been rendered by their anceftors to falfe deities. Others will ^lave the tonfure to typily the dedication of the perfon to the fervice of God ; the cutting off of the hair being always confidered as a mark of fervitude. Be thefe conjeftures as they may, the prieft, after the child is baptized, offers up for him feveral prayers, all alluding to the rite to be performed; and then cuts his hair crofswife, faying, " N the fervant of God is (horn, in the name of the Father, and of the Son, and of the Holy Ghoft, now and for ever, even unto ages- of ages. Amen." We have given a full account of the manner in which the facrament of baptifm is celebrated among the Greeks, that the reader may have fome notion of the childiili fuperftition of that church, with which certain zealous Proteftants in England were very defirous, at the beginning of this century, to form a union. There is no occafion for dwelling fo long upon their other of- The Greeks fices. For the celebration of the Lord's Supper they have three },ave three liturgies that are occafionally ufed, viz. that of St Chryfoflom, which Is in ordinary daily ufe ; that of St Bafil, ufed on particular days ; and that of the pn-fanSiJied, as it is called, which is ufed on the Wed- nefdays and Fridays during the great fall before Eafter. Between the liturgies of St Chryfoifom and St Bafil there is no effentinl difference; and the office of the pre- fanclified is merely a form of difpenfmg the communion with elements which had been confecrated on the pre- if commu rion-offi- ces. C H U neration ?" He then thrufts the fpear o- Church, bliqucly into the loaf, lifting it up, and faying, " For '~~*v •* his life was taken away from the earth," After this he lays down the loaf, and cutti.ig it crofswife, fays, " The Lamb of God, which taketh away the fins of the world, is flain for the life and ialvation of the world." All this, and more to the fame purpole, is uiiqueftion- ably modern; but we have no doubt but that the prieft ufes the words of Chryfoflom himfelf, when, in the confccration of the elements, he fays, " We offer untOTheconft. thee this reafonable, this unbloody facrifice ; and wecrationof implore, we pray thee, we humbly befeech thee, to fend '''^ '''- down the Holy Spirit upon us, and thofe oblations"**"'*' prcfented unto thee ; and make this bread the precious body of thy Chrift ; and that which is in this cup the precious blood of thy Chrift, changing them by thy Holy Spirit." Dr King obferves, that this invocation of the Holy Spirit upon the elements, which in the eaftern church is always ufed after the wends of Chrift, " This is my body, this is my blood, &c." is incontiftent with the Popifh doftrine of tranfubllantiation : and he is un- doubtedly right ; for the church of Rome teaches, that the chajige is made about the middle of the mafs, when the prieft, taking into his hand iirft the bread and then the wine, pronounces over each feparately the facred ' words of confccration j /. e. the words of Chrift. " It is the office of the prieft, in this and in all other facra- nients (fays a dignitary of that church), only to per- form the outward fenfible part ; but the inward invifible effeft is the work of the great God, who accordingly changes the fubflance of the bread and wine into the body and blood of Chrift the very inftant that the fa- ceding Sunday. We would gladly infert the liturgy of cred words of confccration are pronounced by the prieft St Chryfoftoni, or at leaft fuch an abftraft of it as we have given of the form of adminiftering baptifm ; but as our limits will not permit us to do fo, we muft refer fuch of our readers as have any curiofity refpefting fubjeCls of this nature to Dr King's Rites and Ceremo- nies of the Greek Church. It is proper, however, to obferve here, that many fUperftitious ceremonies have been added to the fervice fince the age of St Chryfoflom, and that no man can compare his genuine works with the liturgy which now goes under his name, and entertain the fmalleft doubt jg but that the latter has been greatly, though gradually, Strange ce- corrupted. Li the offertory there Is a ftrange ceremo- remonyat ny, called the Jlaying of the Holy Lamb, when the prieft, taking into his left hand one of the five loaves which are to be confecrated, thrufts a fpear into the right fide of it ; faying, " He was led as a lamb to the flaugh- ter ;" then into the left iide, adding, " And as a blame- lefs lamb before his fhearers Is dumb, fo he openeth not his mouth :" then into the upper part of the loaf; fay- ing, " In his humiliation his judgment was taken away :" and into the lower part ; adding, " And who fliall de- the offer, tory, over them." But if this be fo, it would be impious, and we believe that by the church of Rome it is deem- ed impious, to pray afterwards, that God would fend down his Holy Spirit to change into the body and blood of Chrift elements which he had already changed into that body and blood, in confequence of the prieft's pronouncing over them the all-powerful words of Chrift. Yet is it certain, that in the prefent Greek church tran- fubllantiation is as much an article of faith as in the church of Rome ; for now every bifhop at his confe- cration declares, in the moil lolemn manner, that he be- 18 lieves and " underftands that the tranfubftantiation ofTranfuh- the body and blood of Chrift, in the holy fupper, is ef.ft^""ation. fedled by the influence and operation of the Holy Ghoft, when the bifhop or prieft invokes God the Fa- ther in thefe words, and make thit bread the precious body of thy Chrijl, &c." This is indeed a different ac- count from that of the Latin church of the time at which this portentous change Is wrought; but fuch dif- ference is a matter of very little importance (g). \T the change itfelf be admitted, the confequence muft be the fame, whether it be fuppofed to take place when the (g) Mr Bruce feems to doubt whether tranfubftantiation be the doftrlne of the Abyflinlan church, and relates a converfation which he had on the fubjeft with a prieft ; who folemnly affirmed, that he never believed in the •converfion of the fubftance of the bread and wine into the fubftance of our Saviour's body and blood. It muft be remembered, however, that the prieft had at the time a powerful reafon for wlfhing that doctrine not to be true. The Jefults uniformly atteft, that the Abyffinians believe in the real prefence ; though it muft not be forgotten that Ludolf was of a different opinion, and that no maa hadftudied the language of Abyfiinla more fuccefrfully than he. C H U Ofiu^fh- tho pritfV pronounces the words of iiiditution, or aftcr ^■^-~\ he lias invoked tlie dcfcent of the Holy Glioll ; in ei- ther calc it leads to idolatry. It may be proper to mcn- tiim, that in the Greek church it is deemed effential to the validity of this holy facrament, that a little warm water be mixed with the wine ; that the napkin, which is fpread over the holy table, and anfvvers to the cor- ^9. parale of the church of Rome, be confecrated by a bi- rhe laity ^^ ^^^ ^)^^^ -^^ \\^msi fome fmall particles of the re- ;omm"m ,. ' ^ • i • i i i t i ■atcinbuthhques 01 a martyr mixed in the web, otnerwile the tu- cinds. charift cannot be adminillered. In this church chil- dren may receive the communion immediately after bap- tifm ; and the lay communicants, of whatever age, re- ceive both the elements together, the bread being fop- ped in the cup : The clergy receive them feparately. We have obferved, that one of the feven myjlerics or facraments of the Greek church is confejfion ; but among the Greeks it is a much more ratiiMial and edifying fcrvice than in the church of Rome. In the (ireek church the end of confeffion is the amendment of the penitent ; in the church of Rome it is to magnify the glory of the prieil. In the former church, the confef- fors pretend only to abate or remit the penance, decla- ring the pardon from God alone ; in the latter, they take upon them to forgive the fin itfelf. The Greek church prefcribes confeffion four times in the year to all her members ; but the laity, for the moft pait, con- fefs only once a year previous to receiving the holy com- munion ; and to this they are in Ruffia obliged by the laws of the empire. The ceremonies with which matrimony is performed in the Greek church confift of three diftindl offices, formerly celebrated at different times, after certain in- [ 435 ] C H U nage, is called the office o( miUiiiiiania! coronati.m, fi-om P'>ii''fh- a lingular circuiVitlancc in it, that of rroivning the par- v ties. This is done in token of the triumph of conti- nence ; and therefore it has, in fome places, been omit- ted at fecond marriages. l'"ormerly thele crowns wei'e garlands made of flowers or flirubs ; but now there are kept, in moil churcheB, crowns of filver or fon\e other metal for the celebration of matrimony. At the put- ting of them on, the pried fays, " N, the fervant of God, is crowned for the handmaid of God ; and " N, handmaid of God, is crowned for the fervant of God, \n the name of the Father, and of the Son, and of the Holy Ghofl ;" adding thrice, " O Lord our God, crown them with glory and honour." The third ceremony is that of dilTolving the crowns on the eighth day ; after which the bride is conduced to the bridegroom's houfe, immediately to enter on the cares of his family. With refpeft to difcipline and government, the Greek Regular church bears a flriking refemblance to that of Rome, atiri fccular In both there is the lame divilion of the clergy intoi-lenjy. regular and fecular ; the fame fpiritual jurifdi(;tion of bifliops and their officials, and the fame diilindion of ranks and offices. lu fome points the difcipline of thi? Greeks differs from that of the Romans. All orders of fecular clergy in the Greek church inferior to biHiops are permitted to marry ; but celibacy, and the alTump- tion of the monallic habits, are indilpenfably requifitc in tliofe who are candidates for the mitre. The regu- lar clergy, fays Mr Dallaway, are generally men of a certain education ; whereas the feculars are of the meaner fort, and illiterate in the extreme. ,, In the Greek church there are five orders of clergy Five orJers tervals, which now make but one fervice. Firlf, there promoted by the impofition of hands ; but it does iiof' ''"^'gy- was a folemn fervice, when the parties betrothed them- felves to each oilier, by giving and receiving rings or other prefents, a In the Greek, as well as in the Latin church, there '^''^ '^^'P** is a fervice, called the divine lampedium, obferved on the '"'"" Thurfday of paffion-week, in imitation of our Saviour's humility. At Conftantinople Jefus Chriil is, on this occafion, perfonificd by the Patriarch, and everywhere clfe by the bifhop of the diocefe, and the twelve apoftles by twelve regular priefls, when a ludicrous conteft arifes who fhall reprefent Judas ; for the name attaches for life. This office is performed at the wefl end of the church, where an arm-chair is fet at the bottom, facing the eall, for the bifhop ; and on each fide are placed twelve chairs for the twelve priefls, who are to repre- fent the twelve apoflles. The prayers and hymns ufed on this occafion are exceedingly beautiful and appro- priate; and when the firfl gofpel, relating our Savlour's- wafhing of his difclples feet, begins to be read, the bifhop or patriarch riles up, and takes off his pontifical veflments by himfelf without afQllance. He then girds himfelf with a towel, and taking a bafon of water in his hand, kneels down and wafltes one foot of each pried, beginning with the youngefl ; and after having wafhed it he kiffes. it. All this is done as the feveral circumdances are read ; and when he comes to the lall prieft, who is fuppofed to reprefent Peter, that pried rffeth up and faith, " Lord, doft thou wafii my feet ?" &c. The blfliop anfwers in the words of our Saviour ; and having finiflied the whole, puts on his garments a- galn, and fits down; and as the fecond gofpel is read (k), repeats the words of our Saviour, " Know ye what I have done unto you ?" &c. The office is certainly an- cient, and, if decently performed, mud be affedllng. ^y Under the word Patriarchs, £«t;yr/. we have gl- The privi* ven a fufBcient account of the rife of the patriarchates, '^K^?"^'''*- as well as of the various degrees of rank and ^u'^o^'ty ^c f-'pIoan» claimed by the bifhops of feveral other fees in the Greek tjnonle. chuch. It may be proper to add here, that after the taking of Conftantinople by Mohammed II. he conti- nued to the patriarch of that city the fame prefent which the Greek emperors had been accuftomed to make — a paftoral daff, a white horfe, and four hundred ducats in gold. To the Greek church and the main, tenance of its clergy he left indeed ample revenues, which they have gradually facrificed to their inconftan- (1) In the Greek church all parldi prieds are c?&iA papas or popes ; and the proto-pope is an archprefbytero (k) The firft gofpel is John xiii. 3 — 12. The fecond gofpel is John xiii. I2— 18. Clinrch, Chufan. C H U cy, their aml)ition, and their private jealoufy however, the patriarch of Conftaiitinopk- fills a very lu- crative and high office. «' Bciides the power of nomi- nating the otlier three patriarchs, and all epifcopal dij;- nitarles (fays Mr Dallaway ), lie enjoys a molt extcnfivc jurifdidioii,ct)nipriring the chiirchesof Anatolia, Greece, Wallachia, Moldavia, and the Idands of the Archipelago. Since the cUfe of the fixtcenth century, the Ruffian church has claimed a jurifdidion independent of the fee of Ctinftaiitinople ; though appeals have been made to that fee in cafes of extraordinary importance. The in- fluence of the patriarch with the Porte is very extenfive, as far as his own nation is concerned. His memorials are never denied ; and he can, in faft, command the death, the exile, imprifonment for life, depofitioii from offices, or pecuniary fine, of any Greek whom he may be inclined to punilh with rigour, or who has treated his authority with contempt. On the death of the patri- arch the moll eager competition is exerted to fill the vacant throne ; which, as It is obtained by bribery and intrigue, is of courfe a very unliable feat to the fuccefs- ful candidate, (honitl another offer to accept the appoint- ment at a lower falary." For a fuller account of the doftrines, difcipline, and worlhip of the Greek church at prefent, we refer the reader to King's Rites and Ce- remonies of the Greek Church in Rvjjia, and to Dalla- •way's Conjlantinople ancient and modern (publilhed in *797)' f''"'" which two works this abflraA has been moftly taken. CHUSAN-IsLANDs, a duller of fmall iflands on the taft coft of China, which were vlfited by Lord Macart- ney in his courfe to Pekin. Molt of thefe Iflands feem to be hills riling regularly out of the fea, and rounded at top, as if any points or angles exilling in their ori- ginal formation had been gradually worn off into a globular and uniform fhape. Many of them, though clofe to each other, are divided by channels of great depth. They rcil upon a foundation of grey or red granite, fome part refenibling porphyry, except in hardnefs. They were, certainly, not formed by the fucceflive alluvian from the earth brought into the lea by the great river at js'hofe mouth they are fituated, like the numerous low and muddy illands at the mouth of the Po, and many others ; but fhould rather be con- fidered as the remains of part of the continent thus fcooped and furrowed, as It were. Into iflands, by the force of violent torrents carrying ofl", further into the fea, whatever was lefs reliltable than the rocks juft men- tioned. Some of them wore a very inviting alpeft ; one in particular, called Poo-too, is defcribed as a per- fedt paradlfe. This fpot was chofen, no doubt, for Its natural beauties, and afterwards embelliflied, by a fet of religious men, who, to the number of three thoufand, poffels the whole of it, living there in a ftate of celi- bacy. It contains four hundred temples, to each of which are annexed dwelling-houfes and gardens for the accommodation of thofe monks. This large monallery, as it may be called, is richly endowed, and its fame is fpread throughout the empire. The Englilh Eaft India Company had once a faftory at Chufan, the principal of thefe iflands, from which they were many years ago interdifted. This, accord- ing to the account of a Chlnefe merchant who remem- bered the faftory, was not occafioned by any offence given by the Englifli, but by the avarice of the officers [.437 ] C I N Still, governing at Canton, who draw large fums from the accumulation of foreign trade in that port. Perhaps, too, the excelfive jealoufy of the Chlnefe government might fancy danger in the unreilrained communication between foreigners and the fubjefts of that empire in feveral of its ports at the fame time. Ting-hal, the chief town of Chufan, reftmbles Ve- nice, but on a fmallcr feale. It is furroundcd, as will as interfered, by canals, over which are thrown (letp bridges, afcended by Iteps like the Rialto. The ftreets are narrow, and paved with fquare flat (tones ; but the houfes, unlike the Venetian buildings, are low and moft- ly of one Itory. The ornaments of thefe buildings are confined chiefly to tht- roofs, on the ridges of which are uncouth figures of animals in clay, flone, or Iron. The town is full of fliops, containing chiefly articles of clo- thing, food, and furniture, diiplayed to full advantage. Even coffins are painted in a variety of lively and con- trdllliig colours. The fmaller quadrupeds, including dogs, intended for food, are expofed alive for fale, as well as poultry, and fifli in tubs of water, with eels in fand. When the gentlemen belonging to the embaffy were at Ting-hai, they were itruck with the number of places where tin-leaf and flicks of odoriferous wood were fold for burning in the temples, which indicated no flight degree of fuperflltion in the people. Super- ftltion, however, made them not idle ; for throughout the whole place there was a quick and aftive indullry. Men pafled bufily through the ftreets, while not an in. dividual was feen afliing alms ; and the women were employed in the fliops. At Chufan, the number of valuable harbours, or places of perfedl fecurlty for fliips of any burden, isalmoil equal to the number of iflands. This advantage, together with that of thtir central fi- tuation, in refpedl to the ealtcrn coft of China, and the vicinity of Corea, Japan, Leoo-keoo,- and Formola, at- trafl confiderable commerce, efpecially to Ningpoo, a city of great trade in the aJjoiniiig province of Che-chi- ang, to which all the Chufan iflands are annexed. From one port in that province twelve veflels fail annually for copper to Japan. According to Brookes, Chufan is in N. Lat. 30. O. and E. Long, i 24. o. CINARA, or Cynara, which we tranflate arti- choke, is, according to Profeflbr Beckmann, the name which was given by the ancients to a plant very diffe- rent from the artichoke of our kitchen gardens, though he admits that they belong to the fame genus. The proofs which he adduces for the truth of his opinion are too tedious to be Introduced Into this Work, efpe- cially as they appear not to us to be abiolutely conclufive. We muft therefore refer the reader to his Hillory of Inventions. The cinara, carduus, and feolymus (fee ScoLYMus in this Supplement), were in his opinion fpecles of the thijlle, of which the roots and young Jhoots, as well as the bottom of the calyx of the laft, were eaten. He has proved indeed, he thinks, that the Greeks and Romans ufed the pulpy bottom of the calyx, and the tendered ftalks and young flioots of ma- ny plants belonging to the thiltle kind, in the fame manner as we ufe artichokes and cardoons, but that thefe latter were unknown to them. " It appears probable (fays he) that the ufe of thefe thiftles, at leaft in Italy and Europe in general, was in the courfe of time laid afide and forgotten, and that the artr« Chbfnn, Cliiara. C I R [ 438 ] C O A Oiiifiibsr articlioke, when it was firll brought to Italy from the „. I'. Lt-vant, was coiifidered 33 a new fpecics of food. It is [[_^ undoubtedly certain that our articlioke was full known - ia that country in the 15th century. Hcnnolaus Bar- barns, who died in 1494, relates that this plant was rfirll; feen at Venice in a garden in 1473, at which time it was very fcaree. About the year 1466, one of the family of Strozza brought the flrft artichokes to Flo- rence from 'Naples. Politian, in a letter in which he defcribes the diflics he found at a grand entertainment in Italy in 1488, among thefe mentions artichokes. Thty were introduced into France in the beginning of the 1 6th century, and into England in the reign of Henry VIII." 1 be original country of the artichoke is unknown. Linna;us fays that it grew wild in Narbonne, Italy, and Sicily, as the cardoon did in Crete ; but our au- thoT has proved very fufficiently, that with refpecl to both thefe fafts the great botanift was mifinformed. The artichoke is certainly known in Perfia ; but Ta- vernier fa) s exprefslv, that it was carried thither, like afparagus and other European vegetables of the kitchen garden, by the Carmelite and other monks ; and that it was only in latter times that it became common. CINNABAR. See Chemistry in this Supplement, n° 91. CIRCLE OF Curvature, or circle of equicurva- ture, is that circle which has the fame curvature with a given curve at a certain point ; or that circle whofe ra- dius is equal to the radius of curvature of the given curve at that point. CiRCLKS of Declination are great circles interfefting each other in the poles of the world. Circle of Dijfipation, in optics. See Optics, En- cychn" 2SS- Circle Equant, in the Ptolemaic aitronomy, is a circle defcribed on the centre of the equant. Its chief life is to find the variation of the firft inequality. Circles of Excurfion are little circles parallel to the ecliptic, and at fuch a diltance from it, as that the ex- curfions of the planets towards the poles of the ecliptic Tnay be included within them ; being ufually fixed at about I o degrees. CiKCLRS of Pnfit'wn, are circles pafling through the common interfeflions of the horizon and meridian, and through any degree of the ecliptic, or the centre of any ftar, or otiier point in the heavens ; and are iifed for finding out the fituation or pofition of any ftar. Thefe are ufually fix in number, cutting the equinoflial into 12 equal parts, which the aftrologers call the celtf t'tal houfes, and hence they are fometimes called circles of the celeflial hotifes. CIRCULAR Lines, a name given by fome authors to fuch ftraight lines as are divided by means of the di- v'fions made in the arch of a circle ; fuch as the fines, tangents, fecants, &c. Circular Parts, called, from the ufe which he firfl made of them, Napier's circular parts, are the five parts of a right-angled or a quadrantal fpherical triangle ; they are the two legs, the complement of the hypothe- liufe, and the complements of the two oblique angles. Concerning thefe circular parts, Napier gave a gene- ral lule in his Logarilhmorum Canonis De/criptio, which is this ; " The redangle under the radius and the fine «f the middle part is equal to the reilangle under the tangents of the adjacent parts, and to the rcftnngte iin» dcr the cofincs of the oppofite parts. The right angle or quadrantal fide being iiegledtd, the two fides and > the complements of the other three natural parts are called the circular parts, as they follow each other as it were in a circular order. Of thefe, any one being fix. ed upon as the middle part, thofe next it are the adja- cent, and thofe fartheft from it the oppolite parts." This rule contains within itfelf all the particular rules for the folution of right-angled fpherical triangles, and they were thus brought into one general comprchcnfive theorem, for the fake of the memory ; as thus, by charging the memorj' with this one rule alone : All the calcs of right-angled fpherical triangles may be refol- ved, and thofe of oblique ones alfo, by letting fall a perpendicular, excepting the two cafes in which there are given either the three fides, or the three angles. A nd for thefe a fimilar expedient has been devifed by Lord Buchan and Ur MInto, which may be thus expreffed : " Of the circular parts of an oblique fpherical triangle, the rcftangle under the tangents of half the fum and half the difference of the fegments at the middle part (formed by a perpendicular drawn from an angle to the oppofite fide), is equal to the re£fangle under the tan- gents of half the fum and half the difference of the op- pofite parts." By the circular parts of an oblique fphe- rical triangle are meant its three fides and the fupple- ments of its three angles. Any of thefe fix being af- fumed as a middle part, the oppofite parts are thofe two of the fame denomination with it, that is, if the middle part is one of the fides, the oppofite parts arc the other two, and, if the middle part is the fupple- ment of one of the angles, the oppofite parts are the fupplements of the other two. Since evei-y plane tri- angle may be confidered as defcribed on the furface of a iphere of an infinite radius, thefe two rules may be applied to plane triangles, provided the middle part be relinked to a fide. Thus it appears that two fimple rules fufifice for the folution of all the poflible cafes of plane and fpherical triangles. Thefe rules, from their neatnefs, and the manner in which they are expreffed, cannot fail of en- graving themfelves deeply on the memory of every one who is a little verfed in trigonometry. It is a circum- ftance worthy of notice, that a perfon of a very weak memory may carry the whole art of trigonometry in his h«ad. CIRCULATING Decimals. See Decimals in this Supplement. CLOCK, a machine for meafuring time, of which a defcription is given in the Encyclopaedia. For the fcientific principles of clock and watch-making, as well as for a (hort account of the moll valuable conftruftions, fee VJATcn-Making in this Supplement. COACH, as we have obferved in the Encyclopsdia, is a very modern invention, if by that word be meant a covered carriage fufpended on fprings. We learn, in- deed, from the laborious refearches of ProfelTor Beck- mann, that coaches of fome kind were known in the be- ginning of the 16th century ; but they were ufed only by women of the firft rank, for the men thought it dil- graceful to ride in them. At that period, when the eleftors and princes did not choofe to be prefent at the meetings of the ftates, they excufed themfelves by in- forming the emperor that their health did not permit them COB [ 439 J COB Coich. them tn ride on horfeback ; and it was confidered as a ■" V 'point eltablilKed, that it was unbecoming for them to ride like women. It is certain, however, that, about the end of the I ;th centyi^y, the emperor, kings, and princes, began to employ covered carriages on journt'ys, and afterwards on public folejnnities. The wedding carriage of the iirft wife of the Empe- ror Leopold, who was a Spaniih princefs, coft, together with the barnefs, 38,000 florins. The coaches ufed by that Emperor are thus defcribed by Kink : " In the imperial coaches no great magnificence was to be feen ; they were covered over with red cloth and black nails. The harnefs was black, and in the whole work there was no gold. The pannels were of glafs, and on this account they were called the imperial glafs coaches. On feftivals the harnefs was ornamented with red filk frin- ges. The imperial coaches were diftinguiflied only by their having leather traces ; but the ladies in the impe- rial faite were obliged to be contented with carriages, the traces of which were made of ropes." At the mag- nificent court of Duke Erneft Auguftus of Hanover, there were in the year 168 1 fifty gilt coaches with fix horfes each. So early did Hanover begin to furpafs other cities in the number of its carriages. The firll time that ambaffadors appeared in coaches on a public folemnity was at the imperial commitfion held at Er- furth in 161 5 refpefting the affair of Juliers. In the hiftory of France we find many proofs that at Paris, in the 14th, ijtli, and even 16th centuries, the French monarchs rode commonly on horfes, the fervants of the court on mules, and the princeffes, together with the principal ladies, fometimes on afies. Perfons of the firll rank often fat behind their equerry, and the horfe was often led by fervants. Carriages, however, of fome kind appear to have been ufed very early in France. An ordinance of Philip the Fair, iffued in i 294 for fup. prefllng luxury, and in which the citizens wives are for-- bid to ufe carriages (c<7rj), is ftill preferved. Under Francis I. or rather about 1550, fomewhat later, there were in Paris for the firll time only three coaches. The oldefl, carriages ufed by the ladies in England were known under the now forgotten name of whirli- cotes. When Richard II. towards the end of the 14th century, was obliged to fly before his rebellious lub- jects, he and all his followers were on horfeback ; his ■ mother only, who was indifpofed, rode in a carriage. This, however, became afterwards fomewhat unfafhion- ihle, when that monarch's queen, Ann, the daughter of the Emperor Charles IV. fliewcd the Englifli ladies how gr;icefully and conveniently (he could, ride on a fide- faddle. Whirlicotes were laid afide, therefore, except at coronations and other public folemnities. Coaches were firil known in England about the year 1580, and, as Stow fays, were introduced from Germany by Fitz- allen, earl of Arundel. In the year 1598, when the Englifh anibaffador came to Scotland, he had a coach with him. Anderfon pLices the period when coaches began to be in common ufe about the year 1605. Tlie eelebrated duke of Buckingham, the unworthy favou- rite of two kings, was the firft perfon who rode with a. coach and fix horfes, in 1619. To ridicule this new pomp, the earl of Northu.mberland put eight horfes to his carriage. Refpeding the progrefs of luxury with regard to coaches, the reader will find much curious information in the firft volume of ProfefTor Bcckmann'a Hiflory of Cobalf. , Inventions. It is perhaps oiw of the moft entertaining """"" articles in that very learned work. The author, how- ever, with all his labour, has not been able to afcertaia the country in which coaches hung on fprings were firfl ufed ; but he feems inclined to give the credit of the invention to Himgary. COBALT (fee CHEMisTKY-/ni/c..-, in this Supple- ment), is a valuable article to potters and dyers. To iit it for their ufe, it is firft roatled and freed from the foreign mineral bodies with which It Is united: It Is then well calcined, and fold either mixed or unmixed with- fine fand under the name of zafter (■^ajfcra) ; or it is melted with filiceous earth and potallies to a kind o£ blue glafs called Jmalt, which when ground very fine is known in commerce by the name of powder blue. All thefe articles, becanfe they are moll durable pigments, and thofe wiilch bed withftand fire, and becaufe one can produce with them every (hade of blue, are employed, above all for tinging cryftal and for enamelling ; for counterfeiting opaque and tranfparent precious llones, and for painting and varnifhing real porcelain and earth- en and potters ware. This colour is indifpenfably ne- ceflary to the painter when he is defirous of imitating the fine azure colour of many butterflies and other na- tural objefts; and the cheaper kind is employed to give a bluelih tinge to new-walhed linen, which fo readily changes to a difagreeable yellow, though not without' injury to the health as well as to the linen. Profcflbr Beckmann, In his Hijlory of Invention!, gives the following account of the paint prepared from co- balt. " About the end of the 15th century cobalt ap- pears to have been dug up in great quantity in the mines on the borders of Saxony and Bohemia, difcover- ed not long before that period. As it was not known at firft. to what uie it could be applied, it was thrown afide as a ufelefs mineral. The miners had an averfion to it, not only becaufe it gave them much frnitlcfs la. bour, but becaufe It often proved prejudicial to their health by the arfenical particles with which it was com- bined; and it appears even that the mineralogieal name ccbalt then firll took its rife. At any rate, I have ne- ver met with it before the beginning of the i6th cen- tury ; and Mathefius and Agricola feem to have firft ufed it in their writings. Frifch derives it from the Bohemian word iow, which fignifies metal; but the conjcfture that it was formed from cohalus, which was the name of .a fpirit that, according to the fuperftitlom notions of the times, haunted mines, dellroved the la- bours of the miners, and often gave them a great deal of unnecelTary trouble, is more probable ; and there ij reafyn to think th-at the latter is borrowed from the Greek. The miners, perliaps, gave this name to th<3: mineral out ol joke, becaufe it thwarted tlieni as much as the fuppofed fpirit, by exciting falfe hopes, and ren- dering their labour often fruitlels. It was once cullo. mary, therefore, to Introduce into the church fcrviee a prayer that God would preferve miners and their works from knlolts and fpirlts. " RefpeAing the invention of making an ufcful kind' of blue glals from cobalt, we have no better information -. than that which Klotzfch has ijublidied from the papers ■ of Chriftian Lehmunn. The former, author of an hlf- torical work rcfpciiting the upper dillrict of the mines in Mifnia, and a ck-r^>;yRuii at bchcibenberg, coUoftcd COB Cobalt, with great diligence every information tViat refpefted ""■v~~— the hiflory of the neighbouring country, and died at a great age in 1688. According to his account, the co- lour mills at the time wlien he wrote were about loo years nld ; and as he began firft to write towards the e.id of the thirty years war, the invention feems to tall about 1540 or 1560. He relates the circumtlance as follows ; ' Chriftopher Schurer, a glafs-maker at Plat- ten, a place which belongs lUil to Bohemia, retired to Neudtck, where he eftablifhed his bulinefs. Being once at Schnccberg, he coUeclcd fome of the beautiful co- loured pieces of cobalt %vhich were found there, tried them in his furnace ; and finding that they melted, he mixed fome cobalt with glafs metal, and obtained fine blue glafs. At firft he prepared it only for the ufc of the putters; but in the courfe of time it was carried as an article of merchandife to Nuremberg, and thence to Holland. As painting on glals was then much culti- vated in Holland, the artifts there knew better how to appreciate this iir/ention. Some Dutchmen therefore repaired to Y^eudeck, in order that they might learn the proccfs ufed in preparing this new paint. By great pro- mifes they perfnaded the inventor to remove to Magde- burg, where he alfo made glafs from the cobalt cf Schnee- berg ; but he again returned to hig former refidence, where he conllrucled a handmill to grind his glais, and afterwards erected one driven by water. At that pe- riod the colour was worth 7^ dollars per cwt. and in Hol- land from 50 to 60 florins. Eight colour mills of the fame kind, for which roafted cobalt was procured in caflcs from Schneeberg, were foon conftruAed in Holland; and it appears that the Dutch mull have been much better acquainted with, the art of preparing, and particularly with that of grinding it, than the Saxons; for the Elec- tor John George fent for two colour-makers from Hol- land, and gave a thoufand florins towards the enabling them to improve the art. He was induced to make this advance chiefly by a remark of the people of Schnee- berg, that the part of the cobalt which dropped down "while it was loading contained more colour than the roalled cobalt itfelf. In a little time more colour-mills ■were erected around Schneeberg. Haas Burghard, a merchant and chamberlain of Schneeberg, built one, by ■which the eleven mills at Flatten were much injured. Paul NordhofT, a Frieflander, a man of great ingenuity, who lived at the Zwittermill, made a great many expe- riments in order to improve the colour; by which he was reduced to fo much poverty that he was at length forced to abandon that place, where he had been em- ployed for ten years in the colour- manufactory. He retired to Annaberg, ellablilhed there in 1649, by the afliftance of a merchant at Leipfic, a colour-manufafto- ry, of which he was appointed the director; and by thefe means rendered the Annaberg cobalt of utility. The confumption of this article, however, muft have decrea- fed in the courfe of time ; for in the year '6,9, when there were mills of the fame kind at niOre of the towns in the neighbourhood of mines, he had on hand above 8000 quintals.' Thus far Lehman n." Kofsler fays, that the Bohemian cobalt is not fo good as that of MIfnia, and that its colour is more like that of afhes. We truft, however, that the qualities of fo- reign cobalt fhall foon be a matter of little importance to the Britilh artift, as a rich mine of this mineral has late- ly been difcovered neair Penzance in Cornwal, 440 ] C O F COFFEA, the CoFFFR-Trec, is a plant which has Coffes, been botanically defcribed in the Encyclopaedia Britan- '""> ' "' nica, where fome account is likcwife given of the modes of cultivating it, as well as ofc the qualities of its fruit. Since that account, however, was publifhed, two works have fallen into our hands, from which we deem it our dnty to make fuch extradts as may not only correifb fome miftakes which we had committed, but alfo com- municate ufeful information to the public. In our former article we adopted the common opi- nion, that the cofiee produced in Arabia is fo greatly fuperior to that which is raifed everywhere elfe, that it is vain to think of cultivating the plant to any extent in the Weft India iflands. We are happy to find that this is 8 vulgar error. In the year 178^, vvh^-'n the cul- tivation of coffee was not fo well underllood in Jamaica as at prefent, fome famples from that iiland were pro- duced in London, and pronounced by the dealers to be e-qual to the very beft brought from the Eall. " Two of the iamples were equal to the beft Mocha coffee, and two more of them fuperior to any coffee to be had at the grocers (hops in London, unlefs you will pay the price of piiked coffee for it, which is two fliillings per pound more than for that which they call the be/} coi- f?e. All the reft of the famples were far from bad cof- fee, and very little inferior, if at all, to what the gro- cers call bejl coffee *." « Mofdcy'i If this be fo, it furely becomes the leglflature oi Tnuti/i am Great Britain to encourage the cultivation of coffee in '#«• the Weft Indies, efpecially as it thrives beft in foil which is not fit for the fugar-cane, and may be raifed in con- Cderable quantities by thofe who are not able to flock a lugar plantation. The encouraging every article which increafes the intercourfe with our colonies is increafing our commerce. The payment for all the ftapks of the Weft Indies is made in our manufaftures ; the fale of which muft increafe in proportion to the numbers that are employed in the cultivation of what is bartered for them. Our Weft India iflands, without draining us of fpecie or bullion, can fupply us with many of thofe ve- ry articles for which we are drained in other parts of the world, and particularly with coffee. To give a detailed account of the introduftion of the coffee-tree into the Weft Indies, would fwell this article to very little purpofe. According to Boerhaave, a Dutch governor was the firft perfon who procured trefti berries from Mocha, and planted them in Batavia; and in the year 1690 fent a plant from thence to Amlter- dam, which came to maturity, and produced thofe ber- ries which have fince furnifhed all that is now cultiva- ted in the Weft Indies. In 1714a plant from the garden of Amfterdam was fent by Mr Pancras, a burgomafter and director of the botanic garden, as a prefent to Louis XIV. which was placed in the garden at Marly. In 1718, the Dutch began to cultivate coffee in Surinam; in 1721, the French began to cultivate it at Cayenne; in 1727, at Martinico; and in 1 7 28, the Englifli began to cuhivate it in Jamaica. As it has been more cultivated in the French Weft India iflands than in the Britifh, it may be of import- ance to our colonifts to be made acquainted with the praftice of the French planters. Accordingly Dr La- borie, a royalift of St Domingo, has lately publifhed a volume for their inftrudion on this fubjed; In which are ] C O F [ 441 oac3. arc niniiy judicious obfervations, the rcfult of lonj,' txpe- farther -V ' rieiice, vcfpeainji the foil fit for a cofl'ee phntatiori ; the various ellablifliments neceffary ; the cultivation of the cofTce-trce through the feveral ftages of its growth and duration ; and the management and ufe ot the ne- groes and cattle. Witli refpeft to foil, it is a faft, fays he, beyond con- tradidion, that low lands, and even the mountains near C O 1< but, on tiie contrary, if to the ead or fonth it be light (which it jjenerally i,), plant ftill nearer. Thus if it be proper on a foutli or ea!l expofure to plant at the dlllance of fix feet, it will be necciTary to plant at the dillance of (even on a well or nortli expofurc, if th': ground be of the fame ijuality as in the other fitua- ^ions. Though coffee, like all other vegetables, grows from the champaign country, are lefs proper for the produc- the feed, Dr Laborie advifcs, in the forming of large tion of cjffee, than lands which are high and at a di- plantations, to make ufe of faplings reared in nurle- Itance from the Tea. The coffee-tree delights in a com- ries ; and the fitnation littell for a nurfery is a plain, or paratively cool climate, and in an open and permeable at leail a ground of gentle afccnt, where the mould is virgin foil; and is hurt by the parching dellruftive air crumbly. In forming a nurfery, fome plant the whole of the fea. The foil on the mountains of St Domingo cherry ; but our author recommends the taking off the confiils generally of a bed of mould more or lefs deep ; flcin, and wafhing the feparated feeds; in which we fufpcft but which, for the produftion of coffee-trees, ought not that he is miflaken, as his praftice is certainly a devia- to be lefs than four or five feet. If the declivity be tion from nature. The nurfery muft be kept very clear gentle, the fofteft and moil friable earth is preferable to of weeds, and neither corn nor any thing elfe fown all others; but in ilecp grounds a firm though not clayey in it. foil, mixed with a proportion of gravel or fniall ftones. The befl feafon for tranfplanting the faplings is du- through which the water may find an eafy way, is the ring the genial rains of April and May, when great at- moft defirable. Tiie colour of the ground is of little tention is required, as the tivafures of future harvefls QOnfequence, though fuch as is fomewhat reddifh is ge- are at ftake. Thofe plants are the fitted for being re- nerally to be preferred. With regard to expofure, the moved which, in the language of our author, are north and weft are the moft eligible in low and hot fi- crowned, or have each four little boughs ; and, if the tuations, becaufe thefe expofures are the coolell ; and feeds were frcfh and fown in furrows about an inch from on the higheft mountains the fouth and ead are to be each other, this perfedlion is generally attained in the chofen, becaufe they are the hotteft. On the whole, courfe of a year. I'TTe faplings mull not be pulled up neither the higheft nor the loweft fituations are the beft, by force, but carefully raifed by means of a flat, fliarp, but thofe which are confiderably above the middle of iron fhovel, thrull deep under their roots; and the foon- the mountains. er they are planted, after being taken up, the better. Whatever be the planter's circumftances in point of In planting, the firft thing (o be done is to thruft fortune, and our author thinks that he ought not to into the ground a dibble, or fhaip pointed ftick, round undertake a fettlement without the command of jcoo which a bole is dug fidin nine to twelve inches in dia- or 4000 pounds fterling, he ought not to fet out with meter, and from fifteen to eighteen in depth. Then a a great number of negroes. If he cannot command a quantity of the mould taken out of the hole is thrown plentiful fupply of viftuals from fome contiguous plan- back into it, till its depth be diminidied about four or fix tation, fix, or at the moft twelve, male negroes, with inches ; and the plant being fupported with tl-.e lefr. hand, in the middle of tlie hole, while the end of it! ftraight root, which our author calls its pivot, touches lightly the new bed, the furrounding mould is with the right hand thrown in, to the height of fix inches. Thio being lightly preffed down with both hands, more earth is thrown in and prelfed in the fame manner, care being taken not to hurt, or bend, or difplace the fapling, which muft be fet fo deep that its two inferior branches be rather below the level of the ground. On this ac- count three or four inches of the hole are left open, which, by the time that thefe branches rife above its margin, are filled up by the furrounding earth. The bufinefs is finiflied by finking the fharp-pointed ftick at the upper margin of the hole, where it ferves as a fmall fence to the infant tree. In hot fituations plantain trees are intermingled with the coflee trees for the pur- pofe of (hade and coolnefs. They are ufually placed in every fourth or fixth row, as the trees are more or lefs dillant, and the expofure more or leis hot. To the bufinefs of planting very foon fucceeds that Colfft. one or two women, will be found fufficient to make the firft effay. After building two huts, one for the mailer or overfeer and the other for the tlaves, they arc to com- mence their operations by cutting away the underwood and creeping plants with the bill, and felling the trees. The trees are to be cut as low as polTible, but the roots are to be left in the ground, becaufe they preferve the foil during the firft period of culture ; and in burning this mafs of wood and ihrubs, the only way fometimes of clearing the ground, care mull be taken that the fire be nowhere fo violent as to convert the foil into the confidence of brick, which it is very apt to do if the foil be clayey. Amid the coffee-trees, after they are planted, may be fown beans, maize, and all kinds of ef- culent plants, pot herbs, *-id roots ; but particular care r.iuft be taken to remove from thefe plantations all creep- ing plants, fuch as melons, yams, potatoes, gourds, and more efpecially tobacco, which multiphcs to a vad ex- tent, and exhaufts the ground. In St Domingo the mod approved method of plant- ing the coffee-tree is in ftraight rows eroding each other of weeding; for there is hardly any plant to which at right angles, and the didance between the plants is weeds are fo pernicious as the coffee-tree : they caufc regulated by the quality and expofure of the ground, it to grow yellovv, fade, wither, and perifli. Wiiere The richer the ioil, the expofures being the fame, and the ground flopes much, efpecially if the foil be foft the cooler the expofure, the quality of the foil being and friable, the weeds muft be taken up by the hand ; the fame, the farther mud the trees be planted afunder. for if they be rooted out by the hoe, the foil will be fo If on the north and wed the ground be good, plant dill loofened that the rains will fweep it away. Some SuppL. Vol. I. Part II. 3 K weedsj Coffca C O F [44 weeds, however, from the depth of their roots muft be dug up ; and when that is the cafe the earth mull be carefully returned and prelFed down. If,' in weeding, any faplings be found withered, others of the fame fize muft be brought from the nurfery and planted in their ftead, with what our author calls their clod, /'. e. with the earth of the nurfery adhering to their roots. If any fapling be found broken or twifted, it mull be cut clofe by the ground in a (loping direcilion, the cut furface facing the north, and it will foon put forth fuck- ers, of which the bell only need be preferved. In plan- tations of eighteen or twenty months old trees are often found with yellow, withered leaves, of which the caufe is fometimes a premature load of fruit, which mull therefore be inllantly removed or the tree will perifh. If, after this, it begin not in a few days to recover, it is probably eaten at the roots bv a large white worm re- fembling a Aug. In that cafe the tree muft be remo- ved, the worm taken out, and before another tree be planted in its ftead, a large hole muft be made in the ground, expofed to the influence of the fun at leaft for a fortnight. The natural height of the coffee tree is from i ^ to l8 feet ; and if left to itfelf it would have the form of moft other trees, I. e. a naked trunk and a branchy head. This is prevented by what the planters C3\\ Jloppiiig ; which is performed by cutting off^ the top of the tree when it has arrived at the proper height, which varies according to circumftances. In the beft foil and moft genial expofure, it is fuff^ered to grow to the height of five feet, and in the worft ftopped at two ; but under the fame afpeft, and on ground of the fame quality, all the trees ought to be ftopped at the fame height. This ope- ration of ftopping is very apt to make the trees put forth fuperfluous branches, which renders them inac- ceffible to the genial warmth of the fun, and, of courfe, deficient jn the powers of fruftification. Thefe muft be plucicii awzy while vet tender; for if they be fuff'er- ed to grow till it become neceffary to cut them, a num- ber of fprouts fucceed ; whereas, when they are pluck- ed, the wound foon cicatrizes, and nothing follows. The faw and the knife, however, muft fometimes be ufed ; for when trees grow old their heads are apt to fpoil ; fuperfluous branches may have been left upon them through negledl ; a bough may ha^e been broken \)y accident ; or branches may be fpent by too great a load of fruit. In all thefe cafes recourfe muft be had to pruning, which fliould be performed immediately af- ter crop, and in fuch a manner as that the tree, when it puts forth its newJaranches, may ftill have as much as poffible its natural or former appearance. This will be accompliftied by cutting the withered bough imme- diately above a knot, whence a good fecondary branch is put forth, which may be eafily trained into the pro- per fhape. Our author diredts the cut to be ahvays made fo as that the Hoping furface ftiall face tlft north ; by which expofure it will efcape the injury which it would otherwife receive from the exceflive heat of the fl»ii. This is a good advice ; but it would ftill be an improvement on it to treat the wound with Forfyth's or Hit's _plafter, which we have defcribed elfewhere (See EncycL Vol. XVIIl. page 562). When the tree is completely pruned, the mofs and ofher excrefcences muft be fcraped from the trunk with a wooden knife, great care being taken not to injure the bark. 2 ] C O F After pruning follows what is called n'ipp'ng. Th.is Coffi is nothing more than the removal of thofe fuperfluous v— fmall twigs which are fent forth from every cut furface in fuch numbers as would foon exhanft the tree ; and it is called nipping, becaufe they are plucked away by the hand, and not cut by the knife. It is needlefs to ad i, that when the ground begins to be impoveriflied, it muft be enriched by proper manure. This is known to every hulbandman both in Europe and in the Weft Indies ; but it is not perhaps fo generally known that the weedings, and chiefly the red (liins of coffee, when gathered into pits, are, in procefs of time, converted into a black mould, which our author fays makes the very beft manure. " The fruit of the coffee, when perfedlly ripe, ap- pears like a fmall oval cherry. Under a red and flnning flcin a whitilh clammy lufcious pulp prefents itfelf, which generally inclofes two feeds. Thefe feeds have one fide flat, the other hemifpherical. The firft is marked with a longitudinal fiffure, and the flat fides are applied to each other. When the feeds are opened, they are found covered with a white, ligneous, brittle membrane, denominated parchment ; on the infide of which is anotlier filver-coloured membrane, exceedingly thin, and feeming to originate from the fiffure of the feeds. Sometimes the cherry has but one feed or grain, which then is in the form of a fmall egg. This is pe- culiar to old decayed trees, or to the extremities of fonie fmall branches." The bufinefs of preparation confifts in taking the feed from its covering, in drying, and in cleaning it fo as to have every advantage at market. Our author thinks that the beft method of preparing the coffee is to ftrip the feed of its outer fldn immediately on its be- ing pulled, and to dry it in its parchment. The pro- cefs has been already defcribed in the Encyclopaedia ; but we believe it to be an injudicious one. We have the authority of a very eminent botanift *, well ac- • Or quainted with all the vegetable produflions of the WeftAK/Z^iA. Indies,, to fay, that the improvement which we have there mentioned, as propofed by Mr Miller, is greatly preferable to Dr Laborie's pradlice. Indeed he him- felf admits, that coffee dried in the cherry is more heavy than when dried in parchment, and that it generally has a higher flavour. Nay, he fays exprefsly, that " if a planter wants to have coffee of the firft quality, either for himfelf or for his friends, he muft fet a part a num- ber of his oldefl trees, and not gather the fruit till it is ripened into drynefs. It is in that manner, he believes, that the Arabians in Yemen make their little harvefls ; and he declares, that coffee thus nourilhed on the tree to the laft moment, muft have every perfeftion of which it is capable." His only ijjaufible objeftion is, that the trees are foon exhaulled when the fruit is left fo long upon them ; but doubtlefs this exhauftion might be retarded by proper manure. The chemical analyfis of coffee evinces that it pof- feffes a great portion of mildly bitter and lightly aftrin- gent gummous and refinous extraft ; a confiderable quantity of oil ; a fixed fait ; and a volatile fait. — Thefe are its medicinal conftituent principles. The intention of torrefaftion is not only to make it deliver thofe prin- ciples, and make them foluble in water, but to give it a property it does not poffefs in the natural ftate of the berry. By the action of fire, its leguminous tafte and the i C O F [ 44.^ ] C O F (lie aqueous part of its mucilage are defiioyed ; its fa- There is fcarcely any vegetable infufion or dccoiftion CoffVa ' line properties are created and difengagcd, and its oil vhofe clients differ from its grufs origin more tlian that I' is rendered empyrenmatic— From thence arifes the pun- ofwhithweare fptaking. Coffee taken in fuhllance . " '^ "^ "'. gent fmcll, and exhilarating flavour, not found in its na- caufes opprefTion at the llomacii, heat, naufea, and in- tural (late. digollion : confcqucntly a continued ufe of a prepara. The ronfting of the berry to a proper decree requires tion of it, in which any quantity of its fulillance is con- great nicttv : Du Four juflly remarks, that the virtue tained, befides being difgulting to the palate, mull lend and ai'reeablenefs of tlie drink depend on it, and that to produce the fame indiipofiiions. The reliduum of both are often injured in the ordinary' method. Ber- the roatted berry, after its virtues are extraded from it, nier fays, when he was at Cairo, where it is fo much is little more than an earthy calx, and mull therefore be \ifed, he was affured by the bell judges, that there were injurious. only two people in that great city, in the public way, The want of attention to this circumftance has been who underllood the preparing it in perfeftion. It it the caufe ot many ot the complaints againfl coffee, and be undcr-doiie, its virtues will not be imparted, and in of the averfion which fome people have to it ; and it is ufe it will load and opprefs the iloniaeh : — If it be from this confideration that coffee fhould not be pre- overdone, it will yield a flat, burnt, and bitter talle, its pared with milk inftead of water, nor fhould the milk virtues will be deilroyed, and in vife it will heat the body, be added to it on the fire, as is fometimes the cafe, for and aft as an aflringent. economical dietetic purpofes, where only a fmall quan- Fourteen pounds weight of raw coffee is generally tity of coffee is ufed, as the tenacity of the milK im- redaced, at the public roalliug ho\ues in London, to pedes the precipitation of the grounds, which is uecef- cieven pounds by the roailiiig ; for which the deiler fary for the purity of the liquor, and therefore neither pays feven pence half-penny, at the rate of five fliillings the milk nor the iugar fhould be added until after it is for every hundred weight. In Paris, the fame quau- made with water in the ufual wav, and the clariticatiou titv is reduced to ten pounds and an half. But the of it is completed (a). — The milk fliould be hot when roafting ought to be regulated by the age and quality added to the liquor of the coffee, which fhould alio be of the coffee, and by nicer rules than the appearance of hot, or both fhould be heated togctiier, in this mode of the fumes, and fuch as are ufually praftiled : therefore ufmg coffee as an article of failenaii.;e. the reduftion mud confequently vary, and no exaft If a knowledge of the principles of coffee, founded ftandurd can be afcertained. Befides, by mixing dif- on examination and various experiments, added to ob- fereut forts of coffee together, that require different de- fervations made on the extenfive and indifcriminate ui'e grees of heat and roafting, coffee has feldom all the ad- of it, cannot authorife us to attribute to it any par- vantages it is capable of receiving to make it delicate, ticular quality untriendly to the human frame ; if the grateful, and pleafant. This indeed can be cffefted no unerring tell ot experience has contirnied its utility, in way fo well as by people who have it roalled in their mai>y countries, not exciufively produclive of thole in- c'wn houfes, to their own tafte, and frelh as they want conveniences, habits, and difeales, lor which its pecu. it for ufe. The clofer it is confined at the time of roall- liar properties ieem moll applicable — let thofe proper- ing, and till ufed, the better will its volatile pungency, ties be duly conlidercd ; and let us reflei'l; on tne flate flavour, and virtues, be preferved. of our atinolpherc, the food and modes of life of the The mode of preparing this beverage for common inhabitants, and the chronical infirmities which derive ufe differs in diflerent countries, principally as to the tlieir origin from thefe fources, and it will be evident additions made to it. — But though that is gejierally what falutary effefts might be cxpcfted from the general underllood, and that tafle, conftitution, the quality of dietetic ufe of coffee in Great Britain, the coffee, and the quantity intended to be drunk, mull COFFER-dams, or Balarilenus, in bridge-building, be confulted, in regard to the proportion of coffee to are encloiures formed for laying the foundation of piers, the water in making it — yet there is one material point, and for other works in water, to exclude the iurround- the importance of which is not well underflood, and ing water, and fo prevent it from interrupting the work- which admits of no deviation. men. The prefervation of the virtues of coffee, particularly COLCHESTER, the chief town in Eflcx, is de- when it is of a fine quality, and exempt from ranknefs, fcribed in the Encyclopaedia Britaunica ; but the de- as has been faid, depends on carefully confining it after fcription is in many refpefts erroneous. The following it has been roafted ; and not powdering it until the account of it was fent to us by an obliging correlpon- time of uiliig it, that the volatile and ethereal princi- dent, who is defirous that the place of his nativity may pies, generated by the fire, may not efcape. But all be accurately defcribed in this Supplement, this will lignify nothing, and the befl materials will be Colchefter is pleafantly fituated upon an eminence, ufelefs, unlefs the following important admonition is gradually rifing on the fouth fide of the river Coliie. flriftly attended to ; which is, that after the liquor is It is the ancient Colonia .CamuloJunum, from which made, it fhould be bright and clear, and entirely ex- word Colonia, both the town and the river Colne re- empt from the leaft cloudinefs or foul appearance, from ceived their names. The Saxons called it Colneceajer. a fufpenfion of any of the particles of the fubftance of That it flourifhed under the Romans, feveral buildings the coffee. full of their bricks, and innumerable quantities of coin 3 K 2 dug (a) It Is not to coffee alone that this refleftion is confined ; every article we ufe as a diluter demands the fame attention. Malt liquors, particularly fmall beer, which in this refpeft is much neglefted, ought always to be carefully fined. The feculent matter entangled by the mucilage of the malt is hurtful to digeftion, and de- trimental to health. COL [ 444 ] COL Colchcfler, Jup up in and about it, fully evince. In tlie year 1763, optical phenomennn, which was full, we believe, at- Colours. jj curious teflVUated cr imfaic pavement was found in tended to by Bnilon. That philofopher wrote a fhort *■ * the garden of the late Mr Barnard, furgeon in the paper on it, which was publifhcd in the Memoirs of High Street, now the property of Mr John Wallis, the Academy of Sciences for the year 174.?. about three feet under the furface of tlie earth. The If a perfon look lledfalUy and for a confiderable time emperor Conllantine the Great was born here, his mo- at a fmall red fqiiare painted upon white paper, he will ther Helen being daughter of Cool, governor or king at lall obferve a kind of green-coloured border furround of this diftriA under the Romans. She is faid to have the red fquare. If he now turn his eyes to fome other found out the crofs of Clirift at Jerufalem ; and on that part of the paper, he will fee an imaginary fquare of a ^ account the arms of this town are a crofs regulee be- delicate green bordering on blue, and correfponding ex- tween three ducal coronets, two in chief and one in aftly in point of fr/.e with the red fquare. This imagi- bafe, the coronet in bafe paffing through the crofs. nary fquare continues vifible for fome time, and indeed The walls wherewith the toivn was encompaffed are does not difappear till the eye has viewed fucceffively a ftiU tolerably entire on the fouth, eafl, and weft fides, number of new objetts. It is to this imaginary fquare but much decayed on the north fide : they are general- that the improper name of accidental colour has been ly about nine feet thick. By a ftatute of King Henry given. If the fmall fquare be yelloiu, the imaginaiy VIII. this town was made tlie fee of a fuffiagan bifhop. This town is the mod noted in England for making of baize ; it is alfo of fpccial note for candying the crin- go roots, and for oyfters. In the conclufion of the civil war 1648, tliis town fquare or accidental colour is blue : the accidental co- lour of green is red ; of blue, yellow ; of white, black ; and on the contrary, that of black is white. The tirll perfon, as far as we know, who gave a fa- tisfactory explanation of thefe phenomena was ProfefTor fuffered a fevere fiege of ten weeks ; and the befieged Scherffer of Vienna, whofe diflertation, tranfiated by making a very rcfolute defence, the ficge was turned into a blockade, wherein the garrifon and inhabitants fuffered the utmoft extremity of hunger, being reduced to eat horfe-flefh, dogs, and cats, and were at laft obli- ged to furrendcr at difcrction, when their two valiant chief officers, Sir Charles Lucas and Sir George Lifle, were fhot under the caflle walls in cold blood. Col- c'helUr is a borough by prefcription, and under that right fends two members to pailiament, all their char- ters being filent upon that head. The charter was re- newed in 1763. The town is now governed by a may. or, recorder, iz aldermen, 18 affiftants, and 18 com- mon-council men. Quarter- fefTions are held here four times in the year. The famous abbey gate of St John is ftill ftanding. Mr Bernoulli, has been publifhcd in the 26th volume of the Journal de Phyllque. In order to underftand thefe phenomena, let us re- colledl, in the firrt place, that light confills of feven rays, namely, red, orange, yellow, green, blue, indigo, violet ; that whitenefs confiils in a mixture of all thefe rays: and that thofe bodies which refletl but very little light are black. Thofe bodies that are of any particular co- lour, refleft a much greater quantity of the rays which conftitute that particular colour than of any other rays. Thus red bodies refleiSl moft red rays ; green bodies, mod green rays, and fo on. Let us recoUeft, in the fecond place, that when two impreffions are made at the fame time upon any of our organs of fenfation, one of which is ftrong and the and allowed to be a furprifing, curious, and beautiful other weak, we only perceive the former. Thus if we piece of Gothic architefture, great numbers of perfons examine by the prilm the rays reflefted by a red rofe, coming from remote parts to fee it. It was built, to- we (hall find that they are of four kinds ; namely red, gether with the abbey, in 1097, and Gudo, fteward to yellow, green, and blue. In this cafe, the impreffion King William Rufus, laid the firft Hone. made by the red rays makes that made by the others St Ann's chapel. Handing at the eaft end of the quite infenfible. For the fame reafon, when a perfon town, is valuable in the efteem of antiquarians as a goes from broad day light into an ill-lighted room, it building of great note in the early days of Chriftianity, appears to him at tirft perfectly dark, the preceding and made no fmall figure in hiftory many centuries pait. llrong impreflion renderi:Tg him for fome time incapable It is now pretty entire. St Botoph's priory was founded by Ernulphus in the rfign of Henry I. in the year 1 1 10. It was demolilh- cd in the wars of Charles I. by the parliament army under Sir Thomas Fairfax. The ruins Hill exhibit a beautiful llle combuftible oxides ; and thofe which containing more than one bafe, may there- fore be termed compound combuftible oxides. The fimple combuftible oxides are only four in number ; namely, oxide of fulphur, oxide nf phofphorus, charcoal, and carbonic oxide gas. All the fimple combuftible ox- ides are by combuftion converted into acids. The com- pound combuftible oxides include by far the greater number of combuftible bodies ; for almoft all the ani- mal and vegetable fubftances belong to them, and the double bafe is ufually carbon and hydrogen. The SUPPORTERS of combujlion are a fet of bodies which are not of themfelves, ill idly fpeaking, capable of undergoing combuftion, but which are abtolutely neceftary for the procefs. All ttie fupporters known at prefent are fix ; viz. i. O'V^en gas ; 2. Air ; 3. Ga- feous oxide of a%ol ; 4. Nitrous gas ; 5. Nitric acid ; and, 6. Oxy-muriatic acid. There are other fubftances, to be mentioned afterwards, to which the author gives the name ol partial fupporters ; but all fupporters contain one common principle, namely oxygen. ,. f.', The INC0M3USTIBLE BODIES are neither capable of undergoing combuftion themfelves, nor of fupporling the combuftion of bodies that are. Of courfe, ti^key are not immediately connedled with combuftion ; tjut they are noticed here, becaufe fome of the alkalies ahd [ 447 ] COM earths, which belong to this clafs, poffefs certain pro. perties in common with combuftible-i, and are cap. i)!e of exhibiting phenomena fomewhat analogcnis to com- buftion ; phenomena which the author defciibes under the title oi femi-condujlivn. From the preceding obfcrvations it is obvious, that, in every cafe of combuftion, there muft be preient a combujlible and a fupporti-r ; and Lavoifier af'certained beyond a doubt, that, during the procefs, the combuf- tible always unites with the oxygen of the fupporter. This new compound ONr author calls a produH of com- buflion ; and maintains that every fuch produ(!'l is either water, or an acid, or a metallic oxide. He admits, in- deed, that other bodies fometimes make their appear- ance during combuftion ; but affirms that thefe, upon examination, will be found neither to be products, nor to have undergone eombutlion. But though the combination of the combuftible with oxygen be a conftant part of combuftion, yet the faci- lity witli which combuftibles burn is not in proportion to their apparent afliiiity for that gas. Phofphorus, for inftance, burns more readily than charcoal ; yet charcoal is capable of abftrafting oxvgen from phof- phorus. The combuftible oxides take fire more rea- dily than fome of the fimple combiiftibles. Thus, char- coal burns moreeafily than carbon or diamond ; and al- cohol, ether, and oils, which are all compound combuf- tible oxides, are exceedingly combuftible ; whereas the metals, which are fimple combuftibles, do not burn, when air is the fupporter, but at a very high tempera- ture. This facility of burning combuftible oxides is probably owing to the weak affinity by, which thiir particles are united ; and to the fame caufe, viz. th.c inferiority of the cohefion of heterogeneous particles, is to be attributed the fa6t, that fome of the compound fupporters occafion combuftion in circumftances when the combuftibles would not be afted on hy fimple ftp. porters. None of the products of comhuftion are themfelves combuftible, in the ufual and proper acceptation of that word. This, however, is not owing to their being fa- turated with oxygen, for fevcral of them are capable of combining with an additional dofe of it ; but duriiiT this new combination no caloric nor light is ever emit- ted, and the compound formed differs effentially from a mere produH ofcomhuftion, being by the additional dofe of oxygen converted into afupporlir. When thi fupporters, thus formed by the combina- tion of oxygen with producls, are made to fupport com- buffion, they do not lofe all their oxygen, but only the additional dofe which cODilhutcd them fupporters. Of courfe they aie again reduced to their original ftate of produds of combuftion ; and as they owe "their proper- ties as fupporters, not to the whole of the oxygen which they contain, but to the additional dole, the au- thor calls them partial fupporters. All the partial fupporters with which we are ac- quainted contain a metallic bafis ; for metallic oxides are the only produfts at prefent known capable of com- bining with an additional dofe of oxygen. The fol lowing oxides, which are produdls ofcomhuftion, com- bined each with an additional dofe of oxygen, are par- tial fupporters : I. Red oxide of iron; 2. Yellow oxide of gold ; 3. White oxide of filver ; 4. Red oxide of mercury ; 5. Arfenic acid ; 6. Red and brown oxides of. Combuf- tio'.. C O M [ 448 j COM Cr.nibuf- of lead; 7. Black, oxide of manganeft- ; 8, Acidulous combiiltion : Lut in thef^" C2(ci n nezv comitiJ!l>/e h al- ''°"- oxide of antimonv ? 9. White oxide of tin. ways evolved. Tlic prccefs is merely an iiUerchange of '~~^''~~' Tlius it :r;ipe:ir's that feveral of the prodiiAs of com- combuiUbility ; for the coinbullible is converted into a ^ biiftion are capable of comljininp with oxygen ; and produtt only by mean.; of a produft. Both the oxy- hence it foKows that the incombulHbility of produAs is gen and the bafc of the produdt having undergone not owing to their want of airinity for oxygen, but to fome other caufe. Thongh no mere proilufl of combuftion is capable of fvppori'tn^ cambnftion, this is not occafioned by any \vant of affinity for combullible bodies ; for feveral of thefe prodnAs are capable of combining with an addi- tional dofe of their bafes. By this combination, how- ever, they lofe their properties as produfts, and are converted' into comlujlMcs : wlience it follows that the procefi inuft differ efleiidally from that of combuftion. Tlius fulphuric acid, a/»Wu<7 of combuftion, by com- bining with an additional dofe of fiJphur or its oxide, is converted into fulphurous acid ; a fubftance which. combuftion, have loft fomething which is efiential to combuftion. The procefs is merely a double decompo- fition. The produft yields its oxygen to the conibuf- tible, while, at the fame time, the combuftible gives out fomething to the bafe of the produft. The com- buftibility of that bale, then, is reftored by tlie lols of its oxygen, and by the reftoration of fomething which it receives from the other combuftible thus converted into a produtl. tiofuppor/ercan be produced by combuftion, or by any equivalent procefs. Now as all the fupporters, except oxygen gas, confift of oxygen combined with a bale, it follows as a coniequence, tiiat oxygen may combine from many of its properties, Dr Thomfon concludes to with a bafe, without lofing that ingredient, whatever it be combiijiible. Thus alfo phofphoric acid, a prodnd is, which gives occafion to combuftion. The mere aft of combuftion, is capable of combining with phofpho- of combination of oxygen with a bafc, therefore, is by- rated iiydro<'en, and forming phojphcrous acid, a com- no means the fame with combuftion. buftible body. When this laft acid is heated in con- Several of the fupporters and partial fupporters are tail vvith a fupporter, it undergoes combuftion ; but it capable of combining with combuftibles, without un- is only the additional dofe of the combuftible which dergoing decompofition, or exhibiting the phenomena onrns, and the whole is converted into phofphoric acid. Hence we fee that it is not the whole bafis of thefe compounds that is combuftible, but merely the addi- tional dofe ; and therefore the compounds themfelvcs may be termed partial com/tii/Iiiks, to indicate, that pari only of the bafe is capable of undergoing combuftion. of combuftion. In this manner the yellow oxide of gold, and the white oxide of filver, combine with am- monia ; the red oxide of mercury with oxalic acid j and oxy-muriatic acid with ammonia. Thus alfo nitre and oxy-muriat of potafti may be combined, or at leall intimately mixed with feveral combuftible bodies, as in Now, fmce the products of combuftion are capable of gunpowder, &c. In all thefe compounds the oxygen combiniuT with oxygen, but never exhibit the pheno- of the fupporter retains each the ingredients proper to mcna of combuftion, except when they are in the ftate itfclf, which render them fufceptible of combuftion ; of partial combuftibles, combuftible bodies muft con- and hence the compound is ftill combuftible. They tain fome principle, which they lofe during combuftion, burn indeed with amazing facihtjf, not only when heat- and to which thev owe their combuftibility ; for after ed, but when triturated or ftruck fmartly with a ham- they have loft it, they unite to oxygen without exhibit- mer ; and have received, in coniequence, the name of ing the phenomena of combuftion. Jetonaiing or fu/minating bodies. Thotigh the produSs of combuftion are not capable Such are the properties of the combuftibles, the fup- of fupporling combuftion, they not unfrequently part porters, and the products ; and fuch the phenomena with their oxygen juft as fupporters do, give it out to which they exhibit when made to aft upon each other, combuftibles, and convert them into produfts ; but du- If -we compare together the fupporters and the produila. ring this procefs no heat nor light is ever evolved. Wa- ter", for inftance, gives out its oxygen to iron, and con- verts it into black oxide, a produft ; and fulphuric acid gives out its oxygen to phofphorus, and converts it into phofphoric acid. Thus we fee that the oxygen of pro- dufts is capable of converting combuftibles into pro- dufts, juft as the oxygen of fupporters ; but during we lliall find that they refemble each other in feverai refpefts. Both of them contain oxygen as an effential part ; both are capable of converting combuftibles into produfts ; and of both feveral combine with combuf- tibles and with additional dofes of oxygen. But they dilfer widely from each other in the phenomena which accompany their aftion on combuftibles. The fuppor- the combination of thelaft only are heat and light e- ters convert thefe bodies into produfts ; and at the mitted. The oxygen of fupporters, then, contains fome- fame time combuftion, or the emiffion of light and heal, thipf which the oxygen of produfts wants. takes place ; whereas the produfts convert combuftibles Whenever the whole of the oxygen is abftrafted from into produfts without any fuch cmiflion. Now as the produfts, the combuftibility of their bafe is reftored as ultimate change produced upon combuftibles by both completely as before combuftion ; but no fubftance is thefe fets of bodies is the fame, and as the fubftance capable of abftrafting the whole of oxygen, except a which combines with the combuftibles is in both cafes combullible or a partial combujlilk \ and when this is the fame, namely oxygen, we muft conclude that this done, the combuftible or partial combuftible lofes its oxygen in the fupporters contains fomething which the own comhuftibihty by the procefs, and is converted into oxygen of the produfts wants ; fomething which fepe- a produft. ''^''^s during the paflage of the oxygen from the fuj)- From thefe fafts, which have been all eftabliihed by porter to the combuftible, and occafions the combuf- Stahl, Lavoifier, and our author, it follows that the tion, or emiffion of fire, which accompanies this paflage. produfts of combuftion may be formed without aftual The oxygen of fupporters, then, contains foms ingre- ^ dient gredi'ent is caloric The combiijlihles and the produHs alfo refemble each other in feveral rcfpefts. Both of them contain the fame or a fjmilar bafe ; both frequently combine with combuftibles, and likcwife with oxygen : but they dif- COM [ 449 3 COM A'tent w!iicK the oxygen of prodm^l;^ wanti. Many cir- nomena which have been thought inconfifterit with that ''')|]^J;'''' cumftances concur to render it probable that this in- theory. , In the year 179^, the alTociated Dutch chcmifta drew the attention of pliilofophers to a curious pheno- nicnon which accompanies the formation of fome ot the fulphurets. When eight parts of copper, iron, lead, tin, or zinc filins^s, and three parts of flowers of ful- fer elfentially in the phenomena which accompany their phur, are mixed together in a glafs^ receiver, and the combination with oxygen. In the one cafe, /fr^ is emit- ted ; in the other, not. If we recolleft that no fub- ftance but a comhuftible is capable of refloringcombnf- tibility to the bafe of a produft, and that at its doing fn, it always lofcs its own combullibility ; and if we rc- coUeft farther, that the bnfe of the produft does not exhibit the phenomenon of combuftion even when it combines with oxygen — we cannot avoid concluding, that all combuftibles contain an ingredient which they lofe when converted into produfts, and that this lofs contributes to the lire which makes its appearance du- ring the converfion. Many circumllances concur to render it probable that this ingredient is liGht. If we fuppofe that the oxygen of ftipporters contains caloric as an eiTential ingredient, and that /ighl is a com ponent part of all combujlibles , the phenomena of com vefl'el placed upon burning coals, the mixture melts, a kind of explofum takes place, it becomes fudJei.ly red hot, and a glow, like that of a piece of red hot charcoal fanned with bellows, rapidly pervades the whole. When this difappears, the mixture is found in the Hate of folid fulphurct of copper, or iron, Sec. The experiment fucceeds whether the ved'el be filled with air, or with azotic or hydrogen gas, or even with wa- ter or mercury. What is fingular in this experiment is the glowing red heat, or the emifiion of fire, which accompanies the combination of the iulphur and metal. This emiflion being the fame which takes place during combuftion, the procefs has been confidered as a com- buftion, and ftated as fuch, by the German chemifts, as an objedtion to Lavoiiier's theory. But our autlior (hews that no objeftion can be urged from this experi- buftion, numerous and intricate. as they are, admit of ment againft the truth of that theory as far as it goes ; an eafy and obvious explanation. The component j)arts of the oxygen of fupporters are two ; namely, i. A bafe ; and, 2. Caloric. The component parts of com- buftibles are likewife two ; namely, l. A bafe ; and, 2. Light. During combuftion the bafe of the oxygen combines with the bafe of the combuftible, and forms the produft ; while at the fame time the caloric of the oxygen combines with the light of the combuftible, and the compound flies off in the form of fire. Thus combuftion is a double decompofition ; the oxygen and combuftible divide themfelves each into two portions, which combine in pairs ; the one compound is the pro- dull, and the other the^r^, which efcapes. Hence the reafon that the oxygen of produfts is unfit for com- buftion : It wants its caloric. Hence the reafon that combuftion does not take place when oxygen combines with produfts, or with the bafe of fupporters : Thefe and that all the phenomena are fully explained by the additions which he has made to it. Thus, we have only to recoUeft, i . That the fulphur is in a melted ftate, and therefore contains caloric as an ingredient ; 2. That the metals which produce the phenomenon contain light as an effential ingredient ; and, 3. That the fulphuret produced is always in a folid ftate — and the explana- tion is llmple and obvious. 'I'ht: fulphur combines with the bafe of the metal, while the caloric, to which the fulphur owed its fluidity, combines with the li^ht of the metal, and the compound flies off under the form oljire. Thus the procefs is exaAIy the fame with combuf- tion, excepting what regards the produCl. The melt- ed fulphur afts the part of the fupporter, while the me- tal occupies the place of the cambujlible. The firft fur- nifhes caloric, the fecond light, while the bafes of both bodies contain no light. The caloric of the oxygen of combine together. Hence we fee that the bafe of fuU courfe is not feparated, and no yfnr appears. Hence phurets (and the fame thing holds of fome phofphurets) alfo the reafon why a combuftible alone can reftore refembles the bafe of produfts in being deftitute of combuftibility to the bafe of a produft. In all fuch light, the formation of thefe bodies exhibiting the fe- cafes a double decompofition takes place. The oxy- paration of fire like combuflion ; but the produdt, differ- gen of the produdl combines with the bafe of the com- ing from a produdl of combuftion in being deilitute of buftible, wliile the light of the combuftible combines oxygen, our author propofes to diftinguilh the procefs with the bafe of the produft." by the title oi femi-comlnflion, to indicate that it pof- Such is the theory of Dr Thomfon, propofed to the felTes one half of the charaCleriftic marks of combuftion. public* under the humble title of Reniarh on Comhujlion. As the author completely eftabhfhes the fafts on which his reafoning refts, we can conceive to it but one plau- fible objeftion. Why is not the caloric of the oxygen feparated when that gas combines with bodies deftitute of light ? That there is caloric emitted on many oc- but is deftitute of the other half. COMPASS, or Mariner's Steering Compass, is an inftrument of fo great value, that every improve- ment of it, propofed by men of fcience or of experience, is entitled to notice. We (hall therefore lay before our readers fome obfervations on the defefts of the compafs cafions, when no light appears with it, is incontrover- in common ufe, which have fallen into our hands fince tible ; but perhaps the matter of light is chemically combined with all bodies which emit heat, though it never flies off but when the heat is great. If this be a faft, and it is not improbable, the theory before us feems to be eftabliftied ; for it not only completes the theory of Lavoifier, but affords an eafy folution to fome phe- .SuppL. Vol, I. Part. II. the article in the Encycloptedia was publilhed. The firft; is by Captain O'Brien Drury of the royal navy, and relates entirely to the needle. " Experiance (fays this officer) Ihews us, that the needle of a compafs, as well as all other magnjts, whe- ther artificial or real, perpetually lofes fomething of its 3 L magnetic COM [4 CnmpaiV. magnetic powers, whicli often produces a JifTerence ex- ' ceeding it point; and I am well, convinced that the great errors in fhip-reckonings proceed more frequently from the incorre&nefs of the compafs tlian from any other caufe. " Steel cannot be too highly tempered for th« needle of a fea-compafs, as the more it is hardened the more permanent is the magnetifm it receives ; but, to pre- ferve the magnetifm, and confequently the polarity of the needle, I recommend to have the needle cafed with thill, Wcll-politlieJ, foft iron ; or elfe to have it armed at the poles with a bit of foft iron. I have found, from many experiments, that the cafed needle prtferved its magnetifm in a much more perfeft degree than the reedU not cafed ; and I have fomt times thought that the magnetic power of the cafed needle had inreafed, while the magnetic power of the uncafed and unarmed needle always lofes of its polarity." This is not an opinion taken up at random, but is the rcfult of what appears to have been a fair and ju- dicious experiment ; for our author placed a caftd nee- dle, an armed needle, and one without either cafe or ar- mour, in a room for three months ; each having at that time precifciy the fame direction, and nearly the fame degree of force. At the expiration of the three months, he found that the cafed needle and the armed needle had not in the leaft changed their direction ; hut the other had changed two degrees, and had loft very con- fiderable of its magnetic power. If there was any change in either of the other needles, it was too incon- fiderable to be perceived. Thcfe obfervations feem to be new, and may tend to the improvement of the compafs. But it is not with refpe as the fum of the third and fourth is to the fourth. Composition of Ratios, is the adding of ratios to- gether : which is performed by multiplying together their corrcfpunding terms, viz. the antecedents together, and the confcquents together, for the antecedent and conlequent of the compound ratio ; like as the addi- tion of logarithms is the fame thing as the multiplica- tion of their corrcfponding numbers. Or, if the ternii of the ratios be placed fradion-wile, then the addition or compofition of the ratios is performed by multiply, ing the tractions together. COMPOUND iNTtRKST. See ALCtnsA, Encycl, and Compound jNTEkkiT \n this Supplement. CONCEPTION, a city of Chili in South America, was vifited in 178(1 by the celebrated, though unfortu- nate, navigator La Peroufe, who gives an account of fome particulars relating to it very different from what we have given of it under the article Conception, £n- cycl. So far are the Spaniards trom living in fecurity with refpeft to the Indians, that, accordujg to him, they are under continual alarms of being attacked by thole bold and enterpriling lavages. " The Indians of Chill (fa) s he) are no longer thofc Americans who were inlpired with terror by European wnis. The in- creafe of horfes, which are dilperfed tiuough the inte- rior of the immenfe dtlerls of America, and that of oxen and Iheep, which has alfo been very great, liave converted thefe people into a nation of Arabs, in every- thing refembliiig thofe who inliabit the defcrts of Ara- bia. Conflantly on horfeback, they conlider an excur- fion of two hundred leagues as a very fhort journey. They march accompanied by their flocks ; feed upon their flefh and milk, and fometimes upon their blood ; and cover themfelves with their fl, that aftive iiiftrument of the revolution : amelcttc. • but jificciving the progredlve ferocity of its meafures, he foriook it in March 1792. On the /jthof Auguft, when the king was conduc- ed to the teinpU-, Condorcet was iii\nicd by the Af- fembly to draw up n juflificatory memorial addrefied to all Europe. At the diifolution of that AfTcmbly, he was chofen deputy to the National Convention, and for fijme time atted a diftinguifiied part in its deliberations. He was at the head of the committee appointed to pre- pare the plan of a republican conftitution. But, in the meanwhile, the fadtion of the Mountain, with a pecu- liar energy of charatler, was rapidly acquiring ftrength. The report of.the committee was coldly received — was even treated with contempt ; and, on the jiil of May I~{)3, Robefpierre completely triumphed. Duri.-,g the coiiteft between tiie Mountain and the Briiroti.ies, Condorcet maintained a cautious fdence. For eight months he hardly fpoke in the Convention ; and feems to have been fingularly wary in not rifhing an opinion on any party quettion. At length he was fo far roufed by the indignities which the legifiative body daily endured, that he propofed the diflblution of the Convention, and the calling of a new one. This jjrobably exafperated the Mountain to fuch an exccfs, that in a fubfequent infurreftion his printing-office was dellroyed. He was not, however, included in the lift of profcribed deputies; nor was he one of the members who figned the lamous proteil againlt the proceedings on the 3ifl of May. See Revoh;tion [Encycl), n" 159. But though he could conquer every fentiment of friendfliip, and ftifle every indignant fenfation at the deftruftion of his party, his vanity as an author pro- pelled him to a fatal exertion. When the conftitution of 1793 was accepted, he publilhed jin Addrcjs to all French Ciltzens ; reprobating the extreme rapidity and want of ccnfideration with which it had b;;en framed and accepted, and detailing the numerous afls of vio- lence by which the prevailing party in the Convention had eftablifhed their influence. This rafh ?ft placed him in the power of the Mountain : Cbabot denounced the publication, and moved for a decree of accufation againll Condorcet ; which was immediately granted. He efcaped from the arreft, and concealed himfelf nine months in the houfe of a woman in Paris, who, though (lie knew him only by name, had the generofi- tv to rifli her lite, and fullain all the inconveniences a^ifing from her harbouring fuch a gueft. At length a domiciliary vifit was threatened, and he was obliged to quit his afylum. He had the good fortune, though unprovided with a pafiport or civic card, to efcape through the barrier ; when he went to the country- houfe of a friend on the plain of Mont-Rouge. Un- fortunately his friend was at Paris, and not expelled to return in Icfs than three days ; during which the fugi- tive was obliged to wander about, expofed to hunger, «!old, fufpenfe, and the pain ariiing from a wound in his foot. At length his friend returned into the coun- try, and found him ; but confidering it dangerous to take him to his houfe in the day-time, requefted him to wait till night, when he would receive and conceal him. Condorcet, on that day which his friend had fixed as the end of his miferies, forgot the diftates of prudence, and went to an inn at Chemars, where he ordered an CON His fqualid appearance, dirty cap, torn Condorcet. clothes, leannefs, and voracity, fixed the attention of '*"~'V " ■* a municipal officer, who alked him whence he came, whither he uas going, and it he had a pafiport ? His confution at thcle interrogatoiies betrayed hmi, and he was initantly apprehended. He was coniined that night 111 a dungeon, and in the morning was found dead. He always carried about him a dole ot poilon, with which he terminated his life, to avoid a trial before the revo- lutionary tribunal, and fhun the gradual aj>f road of in- evitable deilruflion. Thus miftrably perifhed a philofopher, whofe " ge- nius (fays Madame Roland) was equal to the conipre- heniion of the vaflefl lubjefts ; but he had no other charafteriilic bcfides fear. It may be faid of his under- flanding, combined with his perlon, that it was a line cfiencc abforbed in cotton. No one could fay of him, that in a feeble body he difplayed great courage ; for his heart and his conftitution were equally weak. After having deduced a principle, or demonflrattd a fatl, in the Affembly, he would give a vote decidedly oppohte ; overawed by the thunder of the tribunes, armed with inlults, and prodigal of threats." It was during the period of his concealment at Pa- ris, uncertain of a day's exiftence, that he wrote his Sketch of the Progreis of the Human Mind ; a pro- dudlion which undoubtedly difplays genius, though it contains fome of the moft extravagant paradoxes ihat ever fell from the pen ot a philofopher. Among other wonderful things, the author inculcates the poiiibiliiy, if not the probability, that the nature of man maygbe improved to abfolutc perfcftion in body and mind, and his exiftence in this world protrafted to immortality. So firmly does he feem to have been perfuaded of the trntii of this unphilofophical opinion, that he fet him» iclf ieriouily to coniider how men fhould conduit them- felves when the population (hould become too great for the quantity of food which the earth can produce; and the only way which he could find for counteracting this evil was, to check population by proniifcuous concubi- nage and otlier practices, with an account of which we will not fully our pages. Yet we are told by La Lande, that this fketch is " only the outline of a great work, which, had the author lived to complete it, would liave been confidered as a monument eretted to the honour oi human nature ! ! !" La Lande, indeed, ipeaks of the author in terms of high refpedt ; and his abilities are certainly unqueilionable : but what fliall we think of the morals of that man, who hiil puriucd with ma- licious reports, and afterwards hired ruffians to aflafTi- nate *, the old Duke of Rochefoucalt, in whofe houfe ^ ~ he had been brought up ; by whom he had been treat- jd/,^ j ed as a fon ; and at whofe folicitation Turgot created 1791. for him a lucrative office ; and by the power of the court raifed him to all his eminence ? There is a living Englifli writer, who has laboured hard to prove that gratitude is a crime. Condorcet muil furely liave held the fame opinion ; and therefore could not blame thofe low-born tyrants who palled againll him what we muft think an unjuil decree of accufation; for it was in fome degree to his writings that thofe tyrants were indebted for their power. About the end of the year '786, Condorcet married Marie-Louile Sophie de Grouchy, whofe youth, wit, and Jaeauty, were kfs attractive in the «yes of a philo- fopher CON [ 455 1 CON Conferva fophcr than the tender and courageous anxiety with in tlie Downs, and wliich had brought with them a CcntigioB^ II which (lie watched the couch, and aflfunged the fufFcr- fpecies of fever that might in every fenfe of the word — — v— ^ Contaijion. .^^_,^ ^^j- ^y^^ ^^^ ^^ ^j^^ prefident du Paty, who had been be termed an epidemy, it will be allowed, that the fuc- ' bitten "by a mad dog. This union, however, we arc ccfs wHiich attended it was fuch that it cannot be too told, was fatal to his repofe ; it tempted him into the generally known. dangfirous "oad of ambition ; and the i-f and by the lat- ter Jiil/er. By the Romans, as we learn from Pliny, it was even employed to ftop veffels of every kind ; but its application to tiiis ufe fetms not to have been very common till the invention of glafs bottles, of which Profeflbr Beckmanu finds no mention before the 15th century. In later times, fome other vegetable produdions have been found which can be employed inlU'ad of cork for the hiflmentioncd purpofe. Among tkefe is the wood of a tree common in South America, particularly in moid places, which is called there monbin or monbnhi, and by botanl.ls _//^on^/;/;.f /kAvj. Thif wood is brought to England in great abnndarce for that ufe. The fpongy root of a North American tree, known by the name of ri^ifftt, is alfo ufed for the lame end, as are the roots of liquorice, which, on that account, is much cultivated in Sclavonia, and exported to other countries. CORNUA Ammonis, in natural hiftory, are foffil (hells, of which a pretty full account is given in the Encyclopaedia. See Cornu Ammonis and Snake- Stones. It was obferved in the laft of thefe articles, that few, if any, of thefe fhells are known in their re- tent ftate, or as occupied by the living animal ; but fome authors have afferted, on the authority of Lin- nseus, that ammonites, with fhells fimilar to all the va- rieties of the fofliloiies, are yet found alive in the depth of the fea. We are much inclined to embrace this opi- nioti ; but it has been controverted by M. de Lamanvn, who accompanied La Peroufe on his voyage of difco- ■very, by fuch arguments as we know not how to an- fwer. This unfortunate naturaiift (fee Lamanon in this Supplement) allows that there are ftill in the fea living (ornua ammonis ; but he thinks that they are in ■very fmall numbers, and materially different from the -greater part of the folTil ones. According to him, thefe Ltd ought to be confidered as a race, formerly the mod numerous of all, of which, either there are no defcend- ants, or thofe defcendants are reduced to a few dege- nerate individuals. That there are no living animals with Ihells of the very fame kind with fome of the folfil tornua ammonis, the follow ir.g obfervations he confiders as a fufEcient proof. " The foffil (hells are very light and thin, whereas the (hells of thofe animals that live in very deep water are always thick and ponderous ; belides, the form of the foffil cornua ammonis points out to us, in fome mea- fure, the organization of the animal which inhabited it. The celebrated Jufiieu woved, in 1721, that there ex- ifted a very clofe analogy between the ammonite and o ] COR nautilus (a). It is well known that the nautilus, by fori filling or emptying a part of its (liell, has the power of * remaining (tationary in any depth it pleafes : the fame was douhtlefs the cafe with the ammonite ; and if this fpecies ilill abounds in the fea, it would furely be occa- fioiially difcovercd by failors. " The waves alfo would throw fragments of it on the (hore ; (i(hermen might fometimes entangle it in their nets ; or, at leafl, there would be fragments (lick- ing to the lead of the founding line when afcertaining great depths. It may alfo be added, that if the am. monites never quitted the abyfs of the fea, thofe which are found petrified vi'Ould not be conftantly met with on the fame level, and in the fame bed, as thofe (hell-fifh that oiily inhabit the (hallows. There are, however, found in Normandy, Provence, Touraine, and a multi- tude of other places, ammonites mixed with turbines, buccina (whelks), and other littoral (hells. They are found, befides, at every degree of elevation from below the level of the fea to the fummits of the higheft moun- tains. Analogy alio leads us to fnppofe, that Nature, who has given eyes to the nautilus, has not rcfufed them to the ammonite : now v.'hat ufe could thefe be of if they remained confined to thofe depths which the light is unable to penetrate ? " The extinftion of the ancient race of ammonites is therefore an eftablilhtd faft, which no rational fuppo- fition can deftroy ; and this fa defirable a pur- nefs, which diflinguilhes all ranks among the Dutch, pofe. A clergyman, who fubfcribes E. C. we fuppofe may indeed prevent the room from having an offenfive as the initials of his name, propofes, through the medi- fcent ; but what can prevent fuch a number of unprin- uni of the Repertory of Arts, to accomplilh it merely by cipled perfons from corrupting each other in Holland, as we know that they do in Great Britain ? The in- troduction of females of loofe charader to felons fufl'er- ing punifhment for their offences in a prifon, is a prac- tice which we trull will be approved only by philofo- phers of the French fchool. The Britifli philofopher, introducing the aftion of a woim or fcrew into the crane. Whenever a worm of two threads is introduced into a machine, all retrograde motion is flopped, unlefs that worm receive its reaflion from the firll moving force ; for, powerfully as a worm adts upon a wheel, a \\heel has no power upon a worm, whatever force may be ap- whom we have already quoted with approbation, is of plied to it. Suppofe, then, the firft motion in a crane opinion, and we heartily agree with him, that " of re- were given by a worm upon the axis of the wliccl in forming punifhments, none prorhifes fo nuiih fuccefs as which the man walks, the man would have perfecl com- that of folitary imprifonment, or the confinement of mand of the machine, to raiie or lower the goods at criminals in feparate apartments. This improvement pleafure, with the remotell pofilbility of being over- of the Amfleudam houle of correftion would augment powered by the dcfcending weight. the terror of tlie punilliment, w'ould feelude the crimi- " Were I to conllruft (fays the author) a crane upon nal from the fociety of his fellow-prifoners, in which fo- this principle, 1 would have the axis of the wheel in ciety the worfe are fure tb corrupt the better ; would which the man walks, and tlie axis of the worm, in fe- wean him from the knowledge of his companions, and parate parts, and occafionally united ty a coupling-box. from the love of thst turbulent pernicious fife in which When goods were to be raifed, the two axes Ihould be his vices had engaged him ; would raife up in him re- .connefted ; when jowered, they might be difunited, . fleftions on the folly of liis choice, and difpofe his mind and the worm turned by a winch, w^hich would be done to fuch bitter and continued penitence, as might pro- much more expeditioufly that way than by the wheel. duce a lalling alteration in the principles of his con- For the reafons before fuggefled, the defccnt of the duft." weight could be accelerated or flopped at pleafure, at In fome houfes of correftion, the prifoners are fub- the difcretion of the perfon turning the winch, je&ed to the difcipline of flagellation at Hated intervals. " This contrivance might be not inconveniently ap- plied (a) We do not know that M. Thouin's journal of his travels has been yet publifted. Extrafts from it have been inferted into the Decade, a periodical publication at Paris, whence this accoujt of the Amjlerdam houfe of correSion was firft copied into the Monthly Magazine for J^ne J 798, C R A [ 464 ] C R A Crane pllcj to 3 crane already ercfted upon the common pn'n- of 40 guineas was adjudged by the fociety to tlie in- *~'~^~"~' ciplc- : Let there be a wheel put upon any convenient vcntor, are as follows -a:;is 111 the machine as it now ftands ; upon this let tliere lie a worm, that can be thrown in or out of gear at pleafure ; and let the lever by which it is done lie within reach of the man's hand in the wheel. The goods being lafteiied to the crane, and raifed off the floor of the warehoufe ready for letting down, the man puts the worm into gear, leaves the wheel, and lets the goods down bv the winch. Provided it can be conve- niently done, it would be advifable to throw the wheel in which the man walks out of gear when the winch is I. It is rutijile, conlifting merely of a wheel and axle. 2. It has comparatively little friction, as is obvious from the bare infpectlon of the figure. _^. It is durable, as is evident from the two properties above mentioned. 4. It is fafe ; for it cannot move but during the plea- fure of the man, and while he is aftually preiling on the gripe-lever. 5. This crane admits of an alniotl in. finite variety of difTorent powers; and this variation is obtained without the leaft alteration of any part of the machine. It, in unloading a veffel, there fhould be made ufe of; this, however, I fliould apprehend, would found goods of every weight, from a few hundreds to a not be a matter of abfolute necellity." ton and upwards, the man that does the work will be Our author is aware of two objections which may be able fo to adapt his llrength to each as to raife it in a tirged againft tiie introduction of a worm into a crane fpaca ot time proportionate to its weight ; he walking in the manner which he propofes. The firft ai ifes from always with the iamc velocity as nature and his greatcit the flownefs of the motion produced by the turning of eafe may teach him. a fcrew, which he confiders as unworthy of regard; be- caufe the necefTary fpeed is to be gained by the firft pair of wheels and the diameter of the barrel of the windlafs. To the fecond, arifmg from the fuppofed greater friiition between a worm and wheel, he replies, tliat as the friftion between the teeth of two wheels (if not formed on the true epicycloidal principle) mud, while it lafts, be greater than between a worm and wheel for the fame fpace of time, it feems no unrcafonable fuppo- fition that the aggregate of friftion will, in the two cafes, nearly balance each other ; efpecially if it be taken into the account, that to obtain the power of one worm and wheel, there will be, in moll cafes, re- It is a great difadvantage in fome cranes, that they take as long time to raiie the fmajlcll as the largeft weight, unlefs the man who works them turn or walk with fuch velocity as muft foon tire him. In other cranes, perhaps, two or three different powers may be procured ; to obtain which, fome pinion mull be Ihift- ed, or freflt handle applied or reforted to. In this crane, on the fontrary, il the labourer find his load fo heavy as to permit him to alcend the wheel without its turning, let him only move a Hep or two toward the circumference, and he will be fully equal to the taflv. Again, if the load befo light as fcarcely to rtfift the ac- tion of his feet, and thus to oblige him to run through * See Mt. 117. Eiicycl. Plate XX, quired two pair of wheels, and two additional axes — all fo much fpace as to tire him beyond neceflity, let him which will add to the friftion. But, grafting the ba- move laterally towards the centre, and he will foon feel lance of friction to be againft the aftion of the worm, the place , where his flrength will luffer the leall fatigue the power to overcome it is greater in proportion than by raiilng the load in qucflion. One man's weight ap. to overcome the fridlion of two wheels. plied to the extrcnjity of the wheel would raife up- Mr James Whyte of Chevening, in the county of wards of a ton; and it need not be added, that a lingle- Kent, whofe improvement in the conftruclion of pullies fheavcd block would double that power. Suffice it to has, with due rtfpeft, been noticed elfewhere *, gives, fay, that the fize may be varied in any required ratio ; in the TranfaCt'wiis of the Society for the Encouragement of and that this wheel will give as great advantage at any jlrts, &c. the following defcription of a new crane for point of its plane as a common walking-wheel of equal wharfs: diameter, as the inclination can be varied at pleafure, A (fig. I.), a circular inclined plane, moving on a as far as expediency may require. It may be neceflary pivot underneath it, and carrying round with it the to obferve, that what in the figure is the frame, and axis E. A pcrfon talking on this plane, and preffing fcems to form a part of the crane, mull be Conlidered againft. the lever B, throws ofl the gripe D, by means as a part of the houfe in which it is placed ; fince it of an iron rod C ; and thus admits the plane and its would be moltly unneccflary fliould fuch cranes be ereil- axis to move freely, and raife the weight G by the coil- ed in houfes already built. With refpcft to the hori- ing of the rope F round the axis E. zontal part, by walking on which the man who attends To fhew more clearly the conflruftion and aftion of the gib occafionally aflifts in raifing the load, it is not the lever and gripe, a plan of the circular inclined plane, an elTential part of this invention, where the crane is with the lever and gripe, is added (fee fig. 2.), where not immediately contiguous to the gib, although, where B reprefents the lever, D the fpiing or gripe. In this it is, it would be certainly very convenient and econo- plan, when the lever B is in the fituation in which it mical. now appears, the fpring or gripe D prefTes againft the Crane is alfo a popular name for a fyphon, employ- periphery of the plane, as (hewn by the double line, ed in drawing oft liquors. and the machine cannot move ; but when the lever B CROSS, in furveying, is an inftrument confifting of is prefTed out to the dotted line H, the gripe is alfo a bra& is^ircle, divided into four equal parts by two lines thrown off to the dotted line I, and the whole macliine crofTmg each other in the centre. At each extremity left at liberty to move. One end of a rope or cord, of of thefe lines is fixed a perpendicular fight, with fmaH a proper length, is fixed near the end of the lever B, holes below each (lit, for the better difcovering of dif- and the other end made faft to one of the uprights, tant objefts. The crofs is mounted on a ftaff or ftand, ferving to prevent the lever moving too far when prefTed to fix it in the ground, and is very ufeful for meafu- by the man. ring fmall pieces of land, and taking offsets, &c. The properties of this crane, for which the premium Caossjliif, or Forejlaff, is a mathematical inftrument of I'HDO'j'.v rj.ATK yrx: Ti.r-V Pic. 8 J-ra<^ Unb} ? .■> t i\ .^K./r C R U [ 465 ] C R U of box or pear-tiee, confifting of a fqnare ftaff t)t iibout long, aiui about half a yard Iruad. round which hangs f . t I • _ 1 £■•. r J.-.' 1.1 i;i... « ^ iV;..,^.. f, u; •! i,_it* .. * ..r _ 1 three feet long, having each of its faces divided lik' ' line of tangents, and having four crofs pieces of une- qual lengths to fit on the ftaff, the halves of tliefc being aa the radii to the tangent lines on the faces of the fiaff. — The inftrument was ufed in taking the altitudes of the celeftial bodies at fefl. CROWN, in aftronomy, a name given to two con- ftellations, the fouthcrn and the northern. Crown, in geometry, a plane ring included between two parallel or concentric periphenes of unequal circles. Cuon-N-Poji, is a poft in Ibme buildings Handing up- right in the middle between two principal rafters; and a fringe foniething more than half a quarter of a yard deep, of which the thread is regularly twilled. The women give proofs of their modelly and decen- cy by their drefs. Their phyfiognomy is agreeable, their colour frefli, their cheeks vermilioned, and their hair long ; they plait it together in one long trefs. They wear a long robe of a fmooth (l{in tied round the loins, like that of a nun; it covers them from the neck as low as the feet; the fleeves reach down to the wrills. Upon this robe they put divers Ikins of otters or other animals to defend thenifelves from the inclemency of the weather. Better dreffed, many of tliem might difpul'- from which proceed ftruts or braces to the middle of charms with the moft handfome Spanilh women ; but each rafter. It is otherwife called a kin^-poj}, or iitig's- diflatisfied with their natural charms, they have recourfc piece, or joggle-piece. to art, not to embellifli, but to disfigure themfelves. La CRUZ, an excellent harbour on the north-well All the married women have a large opening in the uu- coaft of America, difcovered by the Spaniards in 1779. der lip, and this opening or orifice is filled up by u They were introduced into it by a paflage which they piece of wood cut in an oval fliape, of which the fmall- CdWeA Bucarelli's Entrance, and which they placed in ell diameter is almoll an inch; the more a woman is ad- 550 18' N. Lat. and 1390 15' W. Long, from the meri- vanced in years, the more this curious ornament is cx- dian of Paris. There is no good reafon to quellion the tended: it renders them frightful, the old women efpc- exadlnefs of the latitude of this palTage as laid down by cially, whofe lip, deprived of its wonted fpring, and the Spaniards; but the editor of Peroufe's voyage juft- dragged by the weight of this extraordinary jewel, nc- ly concludes, from the furvey made by our celebrated celTarily hangs in a very difagreeable manner. The navigator Captain Cook on the coafls adjacent to the girls wear only a copper needle, which crolTes the lip in entrance of Bucarelli, that this entrance is about 135" the place where the ornament is intended hereafter to 20' to the weft of Paris, or very nearly 133" weft of be placed. Greenwich. Thefe Indians in war make ufc of cuirafies and The Spaniards were not long in the harbour of La fhoulder pieces of a manufafture like that of the whale- Cruz before they received a vifit from the inhabitants bone ftays among the Europeans. Narrow boards or iu its neighbourhood. Bartering took place. The In- fcantlings form, in fome fort, the woof of the texture, dians gave their peltry, and various trifles, for glafs and threads are the warp : in this manner the whole is beads, bits of old iron, &c. By this traffic the Spa- very flexible, and leaves a free ufe to the arms for the niards were enabled to gain a fufficicntly exaft know- handling of weapons. They wear round the neck » ledge of their genius, of their ofFenfive and defenfive coarfe and large gorget which covers them as high as arrar, of their manufaftures, &c. below the eyes, and their head is defended by a morion, Their colour is a clear olive ; many among them or fl iVx with indifference. Vety early in life he took a Itrong attachment to an amiable woman, a Mifs Johnfton, daughter to a clergyman in that neighbourhood, nrarly of his own age, who was prevailed on to join with him in the facrtd bonds of wedlock, at a time when he had nothing elfe to recom- mend him to her except his perfon and difpofitions ; for as to riches and pofTeffions he had little cf thefe to boall of. She was beautiful, had great good fenfe, equani- mity of temper, an amiable difpofitlon, and elegance of manners, and brought with her a little money, which, though it would be accounted nothing now, was fome- thing in thofe days to one in his fitnation in life. After giving to him a numerous family, and participating with him the changes of fortune which he experienced, fhe peacefully departed this life in fumroer 1786. In the year 1746, Cullen, who had now taken the degree of doftor in phyfic, was appointed a lefturer in chemiilry in the univerfity of Glafgow : and in the month of Oftober began his leftures in that fclcnce. His fiiiEjular talents for arrangement, his dillindtnefs of enunciation, his vivacity of manner, and his knowledge of the fcicnce he taught, rendered his leftures intereft- iuT to the (Indents to a degree that had been till then unknown at that univerfity. He became, therefore, in fome mcafure, adored by the ftudcnts. The former pro- feflbrs were ecllpfed by the brilliancy of his reputation ; and he had to experience all thofe little rubs that envy and difappointed ambition naturally threw in his way. Regardlefs, however, of thefe fecret fhagreens, he pref- fed forward with ardour in his literary career ; and, i'upported by the favour of the public, he confoled him- felf for the contumely he met with from a few indivi- duals. His praftice as a phyfician increafed from day to day ; and a vacancy having occurred in the year 1751, he was then appointed by the king profeffor of medicine in that univerfity. This new appointment I'erved only to call forth his powers, and to bring to light talents that it was not formerly known he poffef- fed ; fo that his fame continued to increafe. As, at that period, the patrons of the univerfity of Edinburgh were conltantly on the watch for the moll eminent medical men to fupport the rifing fame of the college, their attention was foon direAed towards Cul- len ; who, on the death of Dr Plumber, profeffor of chemiftry, was, in 1756, unanimonfly invited to accept the vacant chair. This invitation he accepted : and ba- vin"' refigned all his employments in Glafgow, he be- gan his academical career in Edinburgh in the month of Oftober of that year ; and there he relided till his death. If the admiffion of Cullen into the univerfity of Glaf- gow gave great fpirit to the exertions of the ftudcnts, this was ftiU, if poffible, more ftrongly felt in Edin- burgh. Chemiftry, which had been till that time of fmall account in that univerfity, and was attended to by very few of the ftudcnts, inftantly became a favourite ftudy ; and the leisures upon that fclence were more frequented than any others in the univerfity, anatomy alone excepted. The ftudcnts, in general, fpoke of Cul- len with the rapturous ardour that is natural to youth when they are highly pleafed. Thefe eulogiums ap- peared extravagant to moderate men, and could not fail to prove difgufting to his colleagues. A party was formed among the ftudcnts for oppofing this new fa- vourite of the public ; and thefe ftudcnts, by mlfiepre- feuting the dodtrincs of Cullen to otlrers who could not have an opportunity of hearing thefe doflrines them- felves, made even fome of the moil intelligent men in the univerfity think it their duty publicly to oppofe thefe imaginary tenets. The ferment was thus augmented ; and it was fome time before the profeffors dlfcovercd the arts by which they had been impofed upon, and univerfal harmony reftortd. During this time of public ferment, Cullen went fteadily forward, without taking any part himfelf in thefe difputcs. He never gave ear to any tales refpedt- ing his colleagues, nor took any notice of the doftrines they taught : That fome of their unguarded ftrlftures might at times come to his knowledge, is not impof- fible ; but If they did, they fcemed to make no impref- fion on his mind. Thefe attempts of a party of ftudcnts to lower the character of Cullen on his firft outfet in the univerfity of Edinburgh having proved fruitlefs, his fame as a profeffor, and his reputation as a phvficliin, became move and more refpettcd every day. Nor could It well be otherwife : Cullen's profeflional knowledge was always great, and his manner of lefturing fingularly clear and Intelligible, lively and entertaining ; and to his patients, his conduft in general as a phyfician was fo pleafing, his addrefs fo affable and engaging, and his manner fo open, fo kind, and fo little regulated by pecuniary confidera- tions, that it was iHipoftible for thofe w ho had occafion to call once for his medical affiftance, ever to be fatisfied on any future occafion witliout it. He became the friend and companion of every family he vifited ; and his fu- ture acquaintance could not be difpeufed with. But if Dr Cullen in his public capacity deferved to be admired. In his private capacity by his ftudcnts he de. ferved to be adored. His crrduft to them was fo at- tentive, and the intereft he took In the private concerns of all thofe ftudents who applied to him for advice, was fo cordial and fo warm, that It was impoffible for any one who liad a heart fufceptible of generous emotions^ not to be enraptured with a conducSl fo uncommon and. fo kind. Among ingenuous youth, gratitude eaiily de- generates into rapture — into refpedt nearly allied to a- doratlon. Thofe who advert to this natural conftruc- tioii of the human mind, will be at no lofs to account for that popularity that Cullen enjoyed — a popularity, that thofe who attempt to weigh every occurrence by the cool ftandard of reajon alone, will be inclined to think exceffive. It Is fortunate, however, that the bulk, of mankind will ever be influenced in their judgment not lefs by feelings and affeftions than by the cold and phlegmatic diftates of reajon. The adoration which, generous conduft excites. Is the reward which nature hath appropriated exclufivelytodlfinterefted beneficence. This was the fecret charm that Cullen ever carried a- bout with him, which fafclnated fuch numbers of thofe who had Intimate accefs to him. This was the power which his envious opponents never could have an op- portunity of feeling. The general conduft of CuUen to his ftudents was thus. With all fuch as he obferved to be attentive and diligent, he formed an early acquai':tance, by inviting them by twos, by threes, or by fours at a time, to fup with him, converfing with tbera on thefe occafions with the Cull C U L the moft engaging eafe, and freely entering with them 'on the fubjedt of their ftudies, their amufements, their ilifficiihies, their hopes, and future profpeAs. In this way he ufually invited the whole of his numerous clafs, till lie made himfelf acquainted with their abilities, their private charader, and their olijedj of purfuit. Thofe among them whom he foui.d moll afliduous, bell dif- pofed, or the moll friendlefs, he invited the moll fre- quently, till an intimacy was gradually formed, which proved highly beneficial to them. Tlieir doubts, with regard to their objefts of ftudy, he liilened to with at- tention, and' folved with the moft obliging condefcen- fion. His librar\-, which confided of an excellent af- fortment of the beft books, efpecially on medical fub- je£ls, was at all times open for their accommodation ; and bis advice, in every cafe of difficulty to them, they always had it in their power moll readily to obtain. They feemed to be his family ; and few perfons of dif- tinguifhed merit have left the univerllty of Edinburgh in his time, with whom he did not keep up a corre- fpondence till they were fairly eftablilhed in bufinefs. By thefe means he came to have a moll accurate know- ledge of the (late of every country, with refpcct to praftitioners in the medical line ; the only ufe he made of which knowledge was, to dircft lludents in their choice of places, where they might have an opportuni- ty of engaging in bufinefs with a reafonable prolpeft of fuccefs. Many, very many, able men has he thus put into a good line of bufinefs where they never could have thought of it themfelves ; and they are now reaping the fruits of this beneficent forelight on his part. Nor was it in this way only that he befriended the lludents at the univerfity of Edinburgh. Pofleffing a benevolence of mind that made him ever think firlt of the wants of others, and recoUefting the difficulties that he himfelf had had to ftruggle with in his younger days, he was at all times fingularly attentive to their pe- cuniary concerns. From his general acquaintance a- niong the ftudtnts, and the friendly habits he was on with many of them, he found no difficulty in dilcover- ing thofe among them who were rather in hampered circumftances, without being obliged io hurt their de- iicacy in any degree. To fuch perfons, when their habits of ftudy admitted of it, he was peculiarly at- tentive.. They were more frequently invited to his lioufe than others; they were treated with more than iifual kindnefs and familiarity ; they were conducted to his library, and encouraged by the moil delicate addrefs to borrow from it ireely whatever books he thought they had occafion tor : and as perfons in thefe circum- ftances were ufually more fliy in this refpedl than others, books were fomcti.-nes prcfTed upon them as a fort of eonllraint, by the Doftor infilling to have their opinion of fuch or fuch paffagesthey had not read, and defiring them to carry the book home for that purpofe. He, in fliort, behaved to them rather as if he courted their company, and ilood in need of their acquaintance than they of his. He thus railed them in the opinion of their acquaintance to a much higher degree of eilima- tion than they could otherwife have obtained ; which, to people whofe minds were deprefled by penury, and whofe fcnfe of honour was fiiarpened by the confciouf- nefs of an inferiority of a certain kind, was fingularly engaging. T^hus they were infpired with a fecret fenfe •f dignity, which elevated their minds, and excited an [ 469 ] C U L uncommon ardour of purfuit, inlUad of that mclancho- Cullcn. ly inaftivity which is lo naturul in fuch circuniltances, '— v~~~ and which too often leads to defpair. Nor was he kfi delicate in the manner of fuppl) iiig their wants, thuiv attentive to dilcover them. He often found out fomc polite cx'cufe tor refilling to take puyu.ei.t for a firit courie, and never was .it a lofs for one 10 an after courfe. Before they could have an opportunity of applying for a ticket, he would fometimes lead the converfation to fome fubjeCt that occurred in the courfe of hisleftures; and as his ledtures were never put in writing by him- felf, he would fometimes beg the f>iVour to fee their notes, if he knew they had been taken with attention, under a pretext of affilling his memory. Sometimes h; would cxprefs a wifh to have their opinion of a paiticu- lar part of his courfe, and prefented them with a ticket for that purpofe ; and fometimes he rcfufed to take payment, under the pretext that they had not leccivtj his full courfe the preceding year, iome part of it ha- ving been neceflarily ojtiltted for want of t me, which he meant to include in this courfe. By fuch dclicat'; addrefs, in which he greatly excelled, he took care to forerun their wants. Thus he not only gave them thy benefit of his own leftures, but by retufing to takj their money, he alfo enabled them to attend thofe of others that were neceflaiy to complete their courfe of lludies. Thefe were particular devices he adopted to individuals to whom economy was neceflary ; but it was a general rule with him, never to take mor.ey from any lludent for more than two couifes of the fame fet of lecturee, permitting him to attend thefe IcAures as many years longer as he pltafed gral'u. He introduced another general rule into the univer- fity, that was diclated by the tame principle of difin. terelled beneficence, that ought not to be here pafTed over in fileuce. Before he came to Edinburgh, it was the cullom of medical profeflbrs to accept of fees for their medical afiillance, when wanted, even from medi- cal lludents themfelves, who were perhaps attending thi; profelTor's own ieftuies at the tinje. But Cullen nevei: would take fees as a phyfician from any lludeut at the univerfity, though he attended them, when called in a,j a phyfician, with the fame affidulty and care as if thev had been perfons of the firll rank, who p^aid him molt liberally. This gradually induced others to adopt a li- milar pradUce ; io that it is now become a general ruir; for medical proftllors to decline taking any fees when their affiftance is neceflary to a Undent. Eor this ufe- fnl reform, with many others, the lludents of the uni- verfity of Edinburgh are iokly indebted to the libciali- ty of Dr Cullen. - ' The firll lectures which Cullen delivered 'm\ Edin- burgh were on chemillry ; and for many years he alfo gave clinical leclures on the cafes which occurred in iIik Royal Infirmary. In the month of February I7f'3, Dr Alfton died, after liaving begun his ulual courfe of lectures on the materia m"epare, yet I made a decent fpeech." " Pray, Sir, brethren (fee Oath, Encycl.^; but rifmg folemnly from (faid Sir David), was your client acquitted or con- his feat, he repeated the words in fo ferious a manner, demned ?" " O (replied the other), moft unjuftly con- as left no doubt in the moft profligate mind but that demned." " That, Sir, (faid the depute advocate) is he was himfelf impreiied with a fenfe of the immediate no good argument for hurrying on trials." prefence of the Supreme Being, and with the firm be- To return from this digreffion, if it be corfidered as lief of a future judgment. When the witnefs appeared ; fuch, it is furely to the honour of Sir David Dalrymple, to be young or ignorant, we have beheld, with the ut- that whatever men thought of his fingularities, his de- moft love and veneration, the pious pains which his traftors concurred with his admirers in believing him Lordfhip took to difcover whether he was duly ac- incapable of mifleading the judge by a falfe ttatement of quainted with the nature and obligation of an oath, be- fadls ; or his clients, by holding out to them fallacious fore he admitted him to fwear; and thoiio-h it is per- grounds of hope. haps impoffible for human vigilance and fagacity to pre- His high i'enfe of honour, and his inflexible Integri- vent perjury altogether in courts of juftici» he mult ty, were indeed univerfally admitted ; and it was witli furely have been a villain uncommonly hardened and art- the warmeft approbation of the public, that in i"65 he ful who could perjure himfelf in the prefence of Lord was appointed one of the judges of the court of feflion, Hailes. In doubtful cafes his Lordlliip inclined always the higheft civil tribunal in Scotland. He took his to the fide of mercy; but when it became his duty tp feat on the bench, according to the ufage of that court, pafs fentence of death upon convicted criminals, he ad- by the title of Lord Hailes, the defignation by which drefl'ed them in a llrain of fuch piety and commlfera- he is generally known among the learned of Europe ; tion, as to draw tears from the. eyes of every beholder, and the expeftations entertained of him were again fan- and was calculated to make a deep and proper impref- guine. His unwearied affiduity in fifting dark and in- fion on the unhappy perfon himfelf. In the difcharge tricate matters to the bottom was well known ; his ele- of this painful duty, we never faw liim furpafled, and gant and conclfe manner of expreffing his fentiments have feldom feen him equalled. was admirably fultcd to the charafter of a judge ; and Had Lord Hailes been confpicuous only as a found his legal opinions had been generally found. Yet it lawyer and an able and upright judge, we (liould not muft; be confefled, that as a judge he was neither fo ufe- have thought his life intltled to a place in this Work ; . ful nor fo highly revered as he ought to have been from but he was no lefs eminent as a man of general erudi- the extent of his knowledge, and his unqueilloned in- tion, and as a voluminous author. His n7, 4to, pp. 26. The Private Correfpondence of Dr Francis Atter- bury, Bilhnp of Rocheller, and his friends, in 1725, ne- ver before publiihed. Printed in 1768, 410. Advcr- tifement, pp. 2. Letters, pp. 10. A fac fimile of the firft from Blfhop Atterbury' to John Cameron of Lochiel, to prove their authenticity. An examination of fome of the Arguments for the High Antiquity of Regiam Majejlatem ; and an In- quiry Into the authenticity of the Leges Malcolmi , by Sir David Dalrymple, 4to, pp. 52. Edin. 1769. Hiftorical Memoirs concerning the Provincial Coun- cils of the Scottifh Clergy, from the earlieft Accounts to the iEra of the Reformation ; by Sir David Dal- rymple. Edinburgh, 1769, 4to, pp. 41. — Nota, Ha- ving no high opinion of the popularity of his writings, he prefiy.es to this work the following motto : " Si de- leftamur quum fcribimus quis eft tarn invidus qui ab eo nos abducat ? fin laboramus quis eft qui alieua; modum ftatuat induftrls." — Ciceio. Canons of the church of Scotland, drawn up in the Provincial Councils held at Perth, A. D. 1242, and 1269. Edinburgh, 1769, 4to, pp. 48. Ancient Scottlfti Poems, publiihed from the MS. of George Bannatyne, 1568. Edin. 1770, l2mo. Pre- face fix pages; Poems pp. 221 ; veiy curious notes pp. 02 ; gloffary and lifts of paftages and words not underftood, pp. 14. The additional cafe of Elizabeth, claiming the title " The and dignity of Countefs of Sutherland ; by her Guar- 3 P dians. DAL [ 482 ] DAL Dalrym- dians. Wherein the fadls and arguments in fupport of P'^^ ^ her claim are more fully ftated, and the errors in the ' additional cafes for the other chimants are detefted, 4to.^ This fingidarly learned and ahle cafe was fub- fcribed by Alexander Wedderhurn (piefent Lord Chan- cellor), and Sir Adam Fergnffon, but is the well-known V'ork of Lord Hailes. It ought not to be regarded merely as a law-p^per of great ability, but as a trcatile t)f profound refcarch into the hiilory and antiquity of many important and general points of fucceJTion and family hiilory. Introduftion, pp. 21 ; the firft four chapters pp. 70 ; the fifth and fixth chapters pp. 177. Remarks on the Hlflory of Scotland, by Sir David Dalrymplc. — " Utinam tarn facile vera invenire pofTem quarn falfa convincere," Cicero. — Edin. 177.?, infcribed to George Lord Lyttleton, in nine chapters, pp. 284. 12mo. Hubert! Langueti Epiftolse ad Philippum Sydneium Equitem Anglum, accurante D. Dalrymple de Hailes, Eq. Edinburgh, 1776, 8vo. Infcribed to Lord Chief Baron Smythe. — Virorum Eruditorum Teftimonia de X.angueto, pp. 7. Epiftolse, pp. 289. Index Nominum, pp. 41. Annals of Scotland, from the Acceffion of Malcolm III. furnamed Canmore, to the Acceflion of Robert I. by Sir David Dalrymple. Edin. 1776, pp. 311. Ap- pendix, pp. 51. Tables of the Succeffion of the Kings of Scotland, from Malcolm III. to Robert I. their marriages, chil- dren, and time of their death ; and alfo of the Kings of England and France, and of the Popes who were their contemporaries. Chronological Abridgement of the Volume, pp. 30. The Appendix contains eight differtatlons : i. Of the law of Evenus and Mercheta Mulierum, pp. 17. 2. A commentary on the 22d ftatute of William the Lion, , pp. 8. 3. Of the 1 8th ftatute of Alexander III. pp. 5. 4. Bull of Pope Innocent IV. pp. 6. 5. Of Walter Stewart Earl of Mcntetth, 1296, pp. 7. 6. Of M'Duif, Ilain at Falkirk in 1298, pp. 3. 7. Of the death of John Comyn, loth February, 1305, pp. 4. 8. Of the origin of the houfe of Stuart, pp. 6. Annals of Scotland, from the Acceflion of Robert I. furnamed Bruce, to the Acceffion of the Houfe of Stuart; by Sir David Dalrymple, Edin. 1779, 4to, pp. 277. Appendix, pp. 54, containing, T. Of the manner of the death of Marjory, daughter of Robert I. pp. 7. 2. Journal of the campaign of Edward III. 1327, pp. 9. 3. Of the genealogy of the family of Seton in the 14th century. 4. Lift of the Scottilh commanders at the battle of Hallidon, 19th July 1383, pp. II. 5. Whether Edward III. put to death the ion of Sir Alexander Seton, pp. 8. 6. Lift of the Scottifh commanders killed or made prifoners at the battle of Durham, pp. 8. 7. Table of kings, p. i. 8. Correftions and additions to volume i. pp. 16. Chro- nological abridgement of the volume, pp. 39. Account of the Martyrs of Smyrna and Lyons, in the 2d century, 1 2mo, with explanatory tiotes, Edin. 1776. Dedicated to Biftiop Hurd, pp. 68. Notes and illuilrations, pp. 142. This is a new and correft ver- fion of two molt ancient cpiftles, the one from the church at Smyrna to the church at Philadelphia ; the other from the Chriftians at Vienna and Lyons to thofe in Afia and Phrygia — their antiquity and authenticity are undoubted. Great part of both is extrafted from Eu- febius's Ecclefiaftical Hiilory. The former was firft completely edited by Arclibilhop Ulher. The author of the notes fays of them, witii his ufual and lingular modcfty, " That they will afford little new or intertft- ing to men of erudition, though they may prove of fume benefit to the unlearned reader." But the eru- di ion he poffefled in thefe branches is fo rare, that this notice is unneceifary. They difplay much ufeful learn- ing and ingenious criticifm, and breathe the moll ardent zeal, connefted with an exemplary knowledge of Chri- ftianity. N. B. This is the firft volume of the remains of Chriftian Antiquity. Remains of Chriftian Antiquity, with explanatory notes, vol. ii. Edin. 1778, I 2mo. Dedicated to Dr Newton bifhop of Brillol. Preface, pp. 7. This vo- lume contains the trial of Juftin Martyr and his com- panions, pp. 8. Epiille of Dionyfius bilhop of Alex- andria, to Fabius bilhop of Antioch, pp. 16. The trial and execution of Cyprian bilhop of Carthage, pp. 8. The trial and execution of Fruftuofus bifhop of Tarracona in Spain, and of his two deacons, Augurius and Eulogius, pp. 8. The maiden of Antioch, pp. 2. Thefe are all newly tranflated by Lord Hailes from Rui. nart, Eufebius, Ambrofe, &C. The notes and illuilra- tions of this volume extend from p. 47 to 165, and difplay a moft intimate acquaintance with antiquity, great critical acumen, both in elucidating the fenfe and detedling interpolations ; and above all, a fervent and enlightened zeal, in vindicating fuch fentiments and Gondutt as are conformable to the word of God, againft the mahcions farcafms of Mr Gibbon. To this volume is added an Appendix of pp. 22, correfting and vindica- ting certain jjarts of vol. i. Remains of Chriftian Antiquity, vol. iii. Edin. 1780. Dedicated to Thomas Balguy, D. D. Preface, pp. 2. It contains the Hiftory of the martyrs of Palcftine in the third century, tranflated from Eufebius, pp. 94. Notes and iUuftrations, pp. 135 ; in which Mr Gibbon again comes, and more frequently, under review. — The partiality and mifreprcfentations of this popular writer are here expofed in the calmeft and moft fatisfadlory manner. Pity it is that Lord Hailes fliould have printed and publlfhcd thefe valuable volumes, and indeed moft of his other works, at his own expence ; and difperfed them fo liberally to his friends, that they have been little circulated among any other. Odlavius, a Dialogue, by Marcus Minucius Felix. Edin. 1781, pp. 16. Preface. — The fpeakers are, Cos- cilius a Heathen, Oftavius a Chriftian ; whofe argu- ments prevail with his friend to renounce Paganifm and become a Chriftian profelyte. Notes and iUuftrations, pp. I 2-. Of the Manner in which the Perfecutors died ; a Treatife, by L. C. F. Laftantius, Edin. 1782. In- fcribed to Dr Porteous biftiop of Chefter (prefent bi- fliop of London J. Preface, pp. 37, in which it is pro- ved that Laftantius is the author. Text, pp. 125. Notes and iUuftrations, pp. 109. L. C. F. Laftantii Divinarum Inftitutionum Liber Quintus feu de Juftitia, 1777. DifquifitioMS concerning -the Antiquity of the Chri- ftian Church. Glafgow, 1783. Infcribed to Dr Ha- lifax biftiop of Gloucefter, pp. 194. — This fmall origi- . nal DAL r 483 1 DAL Dsliyra- nal and mod excellent work confifls of fix chapters, rcjeftcd all words and plinifcs of French origin, and r-.Iiyni- h'^I Chap I. A commentary on the coiidiiiJi and charaftcr written entirely in the Anglo Saxon dialed. In the l''"' "" ' of Gallic. Afts xviii. 5, 12, 17. — Chap. 2. Of the courfe of the notes many obfciirilies of the original^ not """J^- time at which the Chriftian religion became publicly known at Rome. — Chap. 3. Caufe of the perlecntion of the Chriftians under Nero. In this the hypothefis of Mr Gibbon, vol. i. 4to, p. 641, is examined. — Cliap. 4. Of the eminent Heathen writers who are faid (by Gibbon) to have difregarded or contemned Chridianity, viz. Seneca, Pliny fen. Tacitus, Pliny jun. Galen, Epittctus, Plutarch, Marcus Antoninus. To adverted to by other commentators, are explaiiied. Some ftrange inaccuracies of Mr Gibbon are alio de- tcfted, not included in the mifreprefentatioiis of his two famous chapters. Tliis was the laft work of this truly learned, rcfpedl- ablc, and ufefiil man. Whether he left behind liim any tiling elfe finifhed for the prefs, is known only to his friends. We have repeatedly heard tiiat he was enga- the admirers of Heathen philolophers, and to thofe ef- ged in examining the authenticity of the books of the pecially who flate between them and the Chrillian doc- New Teftament, and that, with the exception of two trine any confanguinity, this chapter is earneilly rccom- or three, he found every verfe contained in it in the mended. — Chap, 5. llludration of a conjefture by Gib- writings of the firft three centuries. Tliis feems in- bon, refpeifting the filence of Dio Caflius concerning deed to have been an objeft in all his works • for at the Chriftians. In this chapter, with extreme impar- the end of each of his tranflations and editions of the tiality, he amplifies and fujiports an idea of Mr Gibbon primitive Chrillian writers, a table is given of paflages on this head. Chap. 6. Of the circumltance.'; rcfpetl- quoted or mentioned by them. If his Lordfliip com- ing Chrillianity that arc to be found in the Auguilan pleted any work of this kind, it (liould not be with- hiftory. held from the public. We may indeed be told that its It feems very probable that the clofe attention which utility is in a great meafure fuperfeded by the laborious Lord Hailes appears to have given to fuch fubjefts, was colle£lions of Lardner (b), and the more elegant work in fome meafure the efFeft of the miftakes and partiality of Paley (c) ; but not to mention the prejudices eene- of Gibbon. In no one work from 1776, the date of rally entertained againft Lardner on account of his evi- Mr Gibbon's firft publication, has he omitted to trace dent bias to Unitarianilm, it would fuiely be proper, in this unfair and infinuating author; but in 1786 he the prefent age of wild opinions, to (hew the multitude, came forth of fet purpofe with the moft able and for- who are guided by authority, how important a fubieft midable reply which he has received, intitled, " An the Chriftian religion was deemed by this learned and Inquiry into the Secondary Caufes which Mr Gibbon accompliftied layman. has aftigned for the rapid growth of Chrillianity ; by DARCY (Count), an ingenious philofopher and ma- Sir David Dalrymple." Edin. 1786 ; gratefully and thematician, was born in Ireland in the year 172c ; but affedionately infcribed to Richard (Hurd) Biihop of his friends being, like many other great and good families Woreeftcr, 410, pp. 213. In five chapters. at that period, attached to the houfe of Stuart, he was at Sketch of the Life of John Barclay, 4to, i 786. 14 years of age lent to France, where he fpent the reft of Sketch of the Life of John Hamilton, a Secular his lite. Giving early indications of a genius for fcience, Prieft, 4to (one of the moft favage and bigotted adhe- he was put under the care of the celebrated Claiiaut rents of Popery, who lived about A. D. 1600.) (fee Clairaut, Eiicycl ), under whofe tuition he ira- Sketch of the Life of Sir James Ramfay, a general proved lo rapidly in the mathematics, that at 17 years officer in the armies of Guftavus Adolplius king of of age he gave a new folution of the problem concern. Sweden, with a head. ing the curve of equal preffure in a refifting medium. Life of George Leflie (an eminent capuchin friar in This was followed the year after by a determination of the early part of the 17th cerrtury, 4to, pp. 24. the curve defcribed by a heavy body, fliding by its own Sketch of the Life of Mark Alex. Boyd, 4to. weight along a moveable plane, at the fame time that Thefe lives were written and publifhed as a fpecimen the preflure of the body caufes a horizontal motion iu of the manner in which a Biographia Scotica might be the plane. executed ; and it is likely that Lord Hailes felefted Though Darcy ferved in the war of 1744, he found purpofely the leaft intereftlng. leifui e, during the buftle of a military life, to fend two The Opinions of Sarah Dutchefs Dowager of Marl- memoirs to the academy : the firft of thefe contained 3 borough, publifhed from her original MSS. 1788, general principle in mechanics, that of the prefervation l2mo, pp. 120. (with a few foot notes by Lord Hailes, of the rotatory motion ; a principle wjiich he again in which he correfts the fplenetic partiality of her brought forward in 1750, by the name of the principle Grace). of the prefervation of adion. He was taken prifoner The Addrefs of Q^ Sept. TertuUian to Scapula Ter- in this war by the Engiifti ; and fuch was either the tuUus, Proconful of Africa, tranflated by Sir David refpeft paid to fcience, or the mercy of the cabinet of Dalrymple, i 2mo. Edin. I 790, infcribed to Dr John St James's, that he was treated, not as an Irifh rebel, Butler, bifhop of Hereford ; preface, pp. 4 ; tranfla- but as a French fubjed fighting for his king and hiit tion, pp. 18 ; original, pp. 13 ; notes and illuftrations, country, pp. 1.^5- In 1760, Darcy- publifhed An Effay on Artillery, This addrefs contains many particulars relating to containing fome curious experiments on the charges of the church after the third century. The tranflator has gunpowder, &c. &c. and improvements on thofe of the 3 P 2 ingenious (b) See his Credibility of the Go/pel Hlftory, and other works, in 11 vols 8vo» (c) See his Evldencet of the Chri/lian Religion, ia 2 vols 8vo. DAT Darcy, Data. ingenious Robins; a kind of expeilmcnts whicli ourau- ttior carried on occalionally to the end of his life. In 1765, lie gave to the public the mofl ingenious of all his works, his Memoir on the Duration of the Senfa- tion of Sight ; in which he endeavours to prove, and indeed complettly proves, that a body may fomttimts pais by our eyes without producing a fenfatioii attend- ed with confcioufnefs or marking its prefencc, other- wife than by weakening the brightnefs of the ubjcA which it may chance to cover in its paffage. If in this work he lliall be thought to have taken hints from I)r Hartley, it is not perhaps too much to fay, that fome of our mod celebrated writers on viiion have fiiice been beholden to Darcy. No man indeed has caufe to be a(hamed of being indebted to him ; for eU his works difplay in an eminent degree the union of genius and phlloft'phy ; but as he nieafured every thing upon the largeft fc;.!e, and lequired extreme accuracy in experi- ment, neither his time, fortune, nor avocations, allow- ed him to execute more than a very fmall part of what he projefteJ. In his difpofilion, Darcy was amiable, fpirited, live- ly, and a lover of indejjendence ; a pafTion to which he nobly facrificed, even in the niidft of literary fociety. — He died of a cholera morbus in 1779, at 54 years of age. He was admitted of the French academy in 1749, and was made penConer-geometrician in 1770. His ciTays, printed in the Memoirs of the Academy of Sci- ences, are various and very ingenious, and are contained in the volumes for the years 1742, 1747, J749> I750j 1751, 1752, I7J3' 17^4. '758' i7S9> '760. i765> and iin torn. r. of the Savans Etraiigers. DATA OF Euclid, the firft in order of the books that have been written by the ancient geometricians, to facilitate and promote the method of refolution or ana- lyfis. In general, a thing is faid to be given which is cither aftually exhibited or can be found out, that is, which is either known by hypothefis, or that can be demonflrnted to be known : and the propofitions in the book of Euclid's data (hew what things can be found out or known, from thoie that by hypothefis are already known : fo that in the analyfis or inveftigation of a problem, from the things that are laid down as given ur known, by the help of thefe propofitions, it is de- monilrated that other things are given, and from thefe laft that others again are given, and fo on, till it is de- monftrated that that which was propofed to be found out in the problem is given; and when this is done, the problem is folved, and its compofition is made and de- rived from the conipofitions of the data which were em- ployed in the analyfis. And thus the data of Euclid are of the mofl general and neceffary ufe in the folution of problems of every kind. Marinus, at the end of his preface to the data, is miilaken in afTerting that Euclid has not uled the fyn- thetical, but the analytical method in delivering them : for though in the analyfis of a theorem, the thing to be demonftrated is affumed in the analyfis ; yet in the demonftrations of the data, the thing to be demonftra- ted, which is, that fomething is given, is never once af- fumed in the dcmonftration ; from which it is manifeft, that every one of them is demonftrated fynthitically : though indeed if a propofition of the data be turned into a problem, the demonltration of the propofition be- [ 4«4 1 D E K Siw/fon's Prejact to Dccimri, comes I he analyfis of the problem. his Etihion of the Diita. Circulating DECIMALS, called alfo recurring or nf eating decimals, are thai^e in whicli a figure or feve- ral figures are continually repeated. Tliiy are diftin- guidicd ihlo Jingle and n:uktph; and thefe again into^«r<; and mixed. A purs Jingle circulate 13 that in which one figure only is repeated ; as "2 22, &c. and is marked thus '2. A. pure multiple circulate is that in which feveral fi- gures are continually repeated ; as'232323, &c. marked •23 ; and •524524, &c. marked "524. A mixed Jingle circulate is that which confifts of a terminate part, and a fuigle repeating figure ; as 4'222, &c. or 4'2. And A mixed multiple circulate is that which contains a terminate part with feveral repeating figures; as 4J'524. That part of the circulate which repeats is called the rcpelend ; and the whole rcpetend, fuppofed infinitely continued, is equal to a vulgar fraftion, whole numera- tor is the repeating number or figures, and its denomi- nator the fame number of nines : fo .2 is = ^ ; anil -23 is = \i ; and -524- is = 4|4- It feems it was Dr Wallis who firft diftinftly confi- dered or treated of infinite circulating decimals, as he himfelf informs us in his Treatife of infinites. Since his time many other authors have treated on this part of arithmetic ; the principal of thefe, however, to whom the art is moftly indebted, are Meflrs Brown, Cunn, Martin, Emerfon, Malcolm, Donn, and Henry Clarke ; in whofe writings the nature and praSice of this art may be fully feen, efpecially in the laft mentioned inge- nious author. DEFERENS, or Deferent, in the ancient aftro- nomy, an imaginary circle, which, as it were, carries about the body of a planet, and is the fame with the eccentric ; being invented to account tor the eccentri- city, perigee, and apogee of the planets. DEFLECTION, the turning any thing afide from its former courfe by fome adventitious or external caufe. The word is often applied to the tendency of a fhip from her true courfe by reafon of currents, &c. which turn her out oF her right way. It is likewife applied- by aftronomers to the tendency of the planets from the line of their projcflion, or ihe tangent of their orbit.. See Astros OMY in this Supplement. DEJECTION, in aftrology, is applied to the planets when in their detriment, as ailrologers fpeak, i. e. when they have loft their force or influence, as is pretended, by reafon of their being in oppofition to fome others which check and counterafl them. Or it is ufed when a planet is in a fign oppofite to that in which it has its greateft effeft or influence, which is called its exaltation. Thus, the fign Aries being the exaltation of the fun, the oppofite fign Libra is its dejeftion. DELIACALPaoBLEM.a celebrated problem among the ancients, concerning the duplication of the cube. DEMI-Bastion, in fortification, a baftion that has only one face and one flank. DENDROMETER, in its ufual acceptation, is the name of an inilrument for meafuring trees, of which the reader will find a defcription in the Encyclopaedia Britantiica. The fame name has been lately given, by DEN [ 485 1 DEN Drndro. WiLLiAM PiTT, Efq; of Pen de ford near Wolvethamp- °"^ '"- ton, to an inftrunicnt propoftd by him for nieafurin^ ' diltances by one obfcrvation. The idea of fuch an inllrunient is not new. It has been freqncntly difcufftd, both in converlation and upon paper; but has been generally treated by found mathe- niaticians with contempt, on the fuppofition of its be- ing founded on fnife principles. Of all this our author is fully aware ; but he, notwithftanding, ftrongly re- commends it to the attention of the ingenious niathe- natical inllrument maker. ■ To determine diftances by one obfervation, two me- thods may be propofed, founded on different principles; the one on the fuppofition of the obferver being in the centre, and the objeft in the circumference, of a circle ; the other, on the contrary fuppofition, of tlie obferver being in the circumference, and the objeCl in the centre. To determine the diftance of any objeft on the firll fuppofition, the bulk or dimenfions of fuch objeft muft be known, either by meafure or eftimation, and the an- gle formed by lines drawn to its extremities being ta- ken by an accurate inllrument, the dillance is eafily cal- culated ; and fuch calculations may be facilitated by tables or theorems adapted to that purpofe. For this method our prtfent inftruments, with a nonius, and the ■whole very accurately divided, are fufficlent ; the only improvement wanting feems to be the application of a micrometer to fuch inftruments, to enable the obferver to read his angle with more minute accuracy, by afcer- taining, not only the degrees and parts of a degree, but alfo the minutes and parts of a minute. As in this method the bulk of inacceffible objefts can only be eftimated, the error in diftance will be ex- aftly in the proportion of the error in fuch eftimation ; little dependence can therefore be placed on diftances thus alcertained. For the purpofes of furveying, in- deed, a ftafF of known length may be held by an affift- ant ; and the angle from the eye of the obferver to its two ends being nieafured by an accurate inilrumenr, with a micrometer fitted to afcertafn minutes and parts of a minute, diftances may be thus determined with great accuracy ; the application of a micrometer to the theodelite, if it could be depended upon, for thus dcter- mining the minute parts of a degree, in fmall angles, is very much a defideratum with the praftical furveyor. This method of meafuving diftances, though plain and fimple enough, our author illuftrates by an example ; Suppofe A, fig. 1. (fee Plate XXI.) the place of the irftrument ; BC the afliftant's ftaff, with a perpendicu- lar pin at D, to enable the affitlant to hold it in its right pofition ; now, if the angle BAG could, by the help of a micrometer, be afcertained to parts of a mi- nute, the diftance fii;ra A to B, or to C, might be eafi- ly calculated by the rules of plane Trigonometry j for which fee that article in the Encyclopedia. But this method of afcertaining diifances cannot be applied to inacceffible objcAs, and it is moreover fub- jeft to the inconvenience of an afiiftant being obliged to go to the objeft whofe diftance is required (an in- convenience almoft equal to the trouble of aftual ad- meafurement) ; therefore the perfedlion of the fecond method propofed, if attainable, is principally to be de- fired ; namely, that of conceiving the obfervation made on the circumference of a circle, whofe centre is in the objcA whofe dillance is to be afcertained ; and, none of Uendro. our inftruments now in ufe being adapted to this mode ""='"■• of obfervation, a new conftruftion of a mathematical in- flrument is therefore propofed, the name intended for which is the dendrometer. Our author admits, that this name is not now iifed for the firft time, though he thinks that the principle has never been applied in praftice, for the familiar pur- pofe of afcertaining tcrreftrial diftances, in furveying, or otherwife, though the fame principle has been lo ge- nerally and fuccetsfully applied in determining the dif- tance of the heavenly bodies by means of their parallax. The following principles of conftniAion are propo- fed, which may perhaps be otherwife varied and impro- ved. O, fig. 2. the objeft of whofe diftance is requi- red ; ABCDE the inllrument in piano ; BC a tele- fcope, placed exaflly parallel to the fide AE ; CE an arcli of a circle, whofe centre is at A, accurately divi- ded from E in degrees, &c. ; AD an index, moveable on the centre A, with a nonius fcale at the end D, graduated to apply to the diviiions of the arch ; alfo with a telefcope, to enable the obferver to difcriminate the objcft, or any particular part or fide thereof, the more accurately. The whole ftiould be mounted on, three legs, in the manner of a plain table or theodolite, and furniflied with fpirit-tubes to adjuft it to an ho- rizontal pofition. The inftrument being placed in fuch pofition, the telefcope BC muft be brought upon the objeft O, or rather upon fome particular point or fide thereof; w>hen, being there faftened, the index AD muft be moved till its telefcope exadlly ftrikes the fame point of the objeft ; then the divifions on the arch ED mark out the angle DAE, which will be exadlly equal to the angle BOA, as is demonftrated in the XV. and XXIX. propofitions of Euclid, Book I. ; and the fide BA, as well as the angles ABO, and BAO, being, already known, the diftance BO or AO may be eafily, determined. As the perfeftion of this inftrument depends altoge-- ther upon its accuracy in taking fmall angles, fo that accuracy mnft depend, not only upon the inftrument's being properly fitted with a micrometer, but alfo in fome meafure upon the length of the line BA in the figure. That line, therefore, might be extended, by the inftrument being conftruAed to fold or flide out to a greater length when in ufe ; upon which principle, connetled with the application of a micrometer, an ac- curate and ufeful irjilrument might certainly be con- ftrudled. To adjuft fuch inftr\in)ent for ufe, let a flaff be held up at a diftance, in the manner of fir. i. exadt- ly equal in leiiglh to the diftance of the two telefcopes, and the index AD being brought exadlly upon the fide AE, if the two telefcopes accurately fliike either end of the ftaff, the inftrument is properly adjulted. The conftrudlion of a iimilar inllrument, on the prin- ciples of Hadley's quadrant, for naval obfervations,. would alfu doubtlefs be an acceptable objedl in navi- gation, by enabling the mariner to afcertain the dif- tances of fhips, capes, and other objcdls, at a fingle ob- fervation ; and that, perhaps, wilfi greater accuracy than can he done by any method now in ufe. For this purpofe, the following conftrudlion is pro» pofed : ABCDE, fig. 3. the inllrument in piano ; O, the objetl whofe diftance is required ; at A, at C, at E, and at 3, are to be filed fpeculums, properly fra- med: Denomina- tor II Default. D E S [ med nnd fitted, that at 3 having only Its lower part quickfilvered, the upper part being left tranfparent to view the objcft ; tlie fpeculum at A being fixed oblique- ly, fo that a line A I, drawn perpendicular to its fur- face, may bifeft the angle BAC in equal parts ; that at C being perpendicular to the line C 2 ; thofe at E and 3 being perpendicular to the index E 3, and that at E being furnifhed with a fight ; the arch DC to be divided from D in the manner of Hadley's quadrant ; the movement of the index to be meafured as before liy a micrometer ; and as the length of the line AE would tend to the perfeftion of the inilrument, it may be con- ftrufted to fold -ap in the middle, on the line C 2, into lefs compafs when not in ufe. The inflrument may be adjuited for ufe by holding up a ftaff at a diftance, as before propofed, whofe length is exaftly equal to the line AE. To jnake an obfervation by this inftrument, it being previoufly properly adjufted, the eye is to be applied at the fight in the fpeculum E, and the face turned to- wards the objeA ; when the o"bjeft being received on the fpeculum A, is refledted into that at C, and again into that at E, and that at 3 on the index ; the index being then moved till the reflefted objeiS in the fpecu- lum at 3 exaflly coincides with the real objeft in the tranfparent part of the glafs, the divifinns on the arch D 3, fubdivided by the micrometer, v.'ill determine the anii-le DE 3 = the angle AOE ; from which the dif- tance O may he determined as before. DENOMINATOR of a Ratio is the quotient arifmg from the divifion of the antecedent by the con- fequcnt. Thus, 6 is the denominator of the ratio 30 to 5, becaufe 30 divided by 1; gives 6. It is otherwife called the exponent of the ratio. DEPRESSION OF a Star, or of the Sun, is its diftance below the horizon ; and is meafured by an arc of a vertical circle, intercepted between the horizon and the place of the ftar. Dbfression of the V'lfible Horizon, or Dip of the Ho- rizon, denotes its finking or dipping below the true horizontal plane, by the obferver's eye being raifed above the furface of the fca ; in confequence of which, the obferved altitude of an odjett is by fo much too groat. DEROOriUST, in Bengal, Entire; as an entire diftrift, oppofed to Kismut, which fee. DESAULT (Peter Jofeph), furgeon in chief to the Hofpital of Humanity, formerly the Hotel-Dieu at Paris, was born on the 6th of February 1744 at Mag- ny Vernois, a village in the neighbourhood of Lure, in the department of Haute Saone (formerly the pro- vince of Franche Comte). His father and mother were in that fituation of life which is removed from want, and yet does not difpenfe with labour ; he himfelf was the youngeft child of a numerous family. At Lure, under the diredion of a private inftruftor, he was taught the firft rudiments of the Latin tongue ; his parents afterwards confided him to the care of the Jefuits, then almoft exclufively entrufted with the edu- cation of youth in the public fchools. This celebrated fociety, prompt in difcovering, as expert at developing, and adroit in appropriating talents, foon diftinguilhed the young ftudent from the crowd ; and he, in his turn, was not difpleafed with the life he led in one of their feminaries. 486 ] D E S On the completion of his fludies, his father, who had rieftatt- deftined him for the church, intimated a wifh that he ' » " ■« fhould apply himfelf to theology ; but his genius had taken a different diredlion, and he was avcrfc to the profeffion of an ecclefiaftic : in (liort, young Default declared that he was determined to betake himfelf to the ftudy of the healing art ; and, after a long and in- effeftual refiftance on the part of his family, he was fent to Befort, in order to ferve an apprentice/hip, as it was then termed, in the military liufpital of that place. He accordingly fpent three years there ; during which he acquired fome knowledge of anatomy, attended to the drefling of the patients, and endeavoured to fupply, by his own obfervations, what was wanting in his inilruc- tion. lu the midft of thefe profefllonal labours, his mind frequently rambled towards another fcience but little coniiefted w itli lurgery : this v.'a3 mathematics, the elements of which he had acquired among the Jefuits. His piogrefs in this favourite ihidy was rapid ; but he fell into one of the many errors fo common among the phyficians of that day ; this confiftcd in a falfe apphca- tion of the rules of geometry to the laws of the animal economy. He not only perufed with avidity the treatife of Bo- relli De Motu An'imalium, but aftually tranflated the whole of it, and even added a commentary, ftill more abundant in calculation than that of the celebrated pro- felTor of Naples. His fuccefs in a branch of phyfiologj- fo much culti- vated at that time, attrafted the attention of one of his fuperiors, a zealous partizan of tlie dodtrine of the me- chanicians, who widied to attach him to his perfon ; but his dcilre of fame required a more extenfive theatre, and liis love of lludy made him folicltous of better means of inftruclion. Paris prefented both thefc advantages; and lie accordingly repaired thither in 1764, at the age of nineteen, in fearch of them. Surgery at that period flouriflied in the capital under the aufpices of a Lafaye, a Morand, an Anduuillet, and a Louis. The fight of fuch great mailers excited the genius of thofe who afpired to emulate them : young Default deemed himfelf worthy of equalling men whom other ftudents were content with only admiring. Ani- mated by this fentiment, he entirely refigned himfelf to his ardour ; anatomy became the fpecial object of his labours, and his diffeclions were not confined to the hu- man body, for he inveftigated, by means of his knife, i. prodigious number of animals of all kinds : at iirft, from a difficulty of procuring human fubjetls, and af- terwards on account of the advantages which he expe- rienced from this general method. In order to become intimately acquainted with our own organization, it is neceffary to compare it with whatever has a refemblance to it in other bodies. He accordingly fpent the greater part of the day in the amphitheatres. The hours ftolen from his favou- rite labours were employed in attending the hofpitals ; he was the firft at the bed of the patient where an ope- ration was to be performed, and was fure to be prefent at the dreflings, on purpofe to examine the refult. The infirmities of mankind, fterile in refpeft to the vulgar, ferved him as the beil treatife for curing them ; and the great furgeons of all nations have formed their mode of praftice by contemplating the fame book. But D E S r 487 ] D E S But hi reckoned too much on a roVitid and vigorous In 1779 he invented the bandage now in ufc for DefauU, "'temperament ; for, after two ytars clofe and afiiduous frailures; by means of which, the fragments being kept '"""~V"~" spph'cation, he fell into a cachetlical habit of body, in a flate of perpetual contact, become confohdated, which had nearly proved mortal, and which colifiiied without the lealt appearance of deformity, an almoll in- him for almoft twelve months to his bed ; but at length, evitable confequence of the former mode, owing partly to the vigour of iiis youth, and partly to On his appointment to the place of furgeon major the attention of his young friend Chopart, his infepar- to the hofpital i/c- la Charite, in 1782, he introduced a able companion in his operations, who attended him al- new method of treatment in oblique fraftures of the fo during his lad illuefr,, and only furvived him a few thigh-bone ; and he alfo healed, by means of a metho- days, he was fo fortunate as to recover. dical compreflion, thofe various ulcers whofe cure had Reftored to life, he forgot that an excefs of atten- hitherto been attended with great difficulty. In addi- tion had condufted him to the very gates of death ; a tion to this, he fubftituted new bandages in fraftures of new career opened to his view, and required new ef- the humerus and clavicle, and adopted a new mode of forts on his part. In the winter of 1766 he commen- treating the hare-lip, fuperior to that ufed by Louis, ced a courfe of anatomy, and foon reckoned tjco pupils. He never recurred to amputation but in extreme cafes, moft of them older than himfelf, who were attrafted by when there was a certainty that diffolution would have the clearnefs of his demoidlrations, the methodical ar- followed a negleft of the operation, rangement of his defcriptions, and, above all, by his in- When a premature death carried off Ferrand, chief defatigable zeal in the fcience of inllruttion. furgeon of the Hotel Dieu in Paris, Default was con. His fuccefs infpired the privileged profefTors, whofe fidered as the moft proper perfon to fucceed him ; and, fchools became deferted, with jealoufy and revenge ; on the demife of Moreau, the whole charge of the hof- they employed the authority of the corporation againft pital devolved on him. After three years of folicita- him, and would have nipped his efforts in the bud, had tions and difputcs, he at length in 1788 proceeded in it not been for the proteftlon of Louis and Lamarti- his long projefled fcheme of eilablifliing a clinical fchool; niere, who were zealous of protecting a youth of ta- and a fpacious amphitheatre was accordingly eredled for lents, whofe fole reproach was, that he had not wealth that purpofe. Scarcely had his firlt (a) courfe corn- enough to purchafe certain franchifes. After all, had menced, when the number of pupils who flocked around it not been for the permiffion he obtained of borrowing him was really aftonifhing. Foreigners repaired from al! the name of a celebrated phyfician, he muft have aftu- parts, and feveral of the neighbouring Itates fcnt ftu. ally defiiled from his leftures. dents to Paris, exprcfsly for the purpofe of affifting at Default's reputation now began to be buzzed about, his demonftrations. More than 600 auditors conftant- and a multitude of patients claimed his affiftance ; but ly attended, in order to learn a new fyftem, confiding he conftantly refufed to pradlife until he (hould be pla- of a fimple mode of treatment, difengaged from ancient ced at the head of fome great eftablifhment. prejudices, and a complex incoherent practice. At length, at the repeated folicitations of his friends, A few of his improvements are here fpeciiied. he prefented himfelf as a candidate to the corporation i. The method of ligature employed by the ancients of furgeons; and they, much to their honour, admitted in the cure of umbilical hernias of children, having been him in 1776, on condition of paying the ufual fees generally omitted in the praftice of the moderns, he ■when convenient. The following is the title of his the- again introduced and perfected this mode, and demoii- (is : " De calculo veficis wiiw/'ue, eoqiie extrnl.vndo, ptie- ftrated, by his fuccefs, its luperiority over conipreflive via fiilione, ope inflrumentt Haukenfani eiiiendaU." bandages. His public lectures were accompanied with as much 2. He was one of the firrt; men in France to extraft celebrity as his private ones. Brilliant difcoveries were the loofe cartilages ( cartilages Jlnttans ) In joints, not the objeft of his anatomical labours, which were al- 3. He employed a new treatment, that of a methodi- ways connefted with the art of healing : he was, how- cal comprefFion, in refpeft to fchirrofities of the rettum;. ever, the firft man in France who taught furgical ana- in order to which he introduced a candle or bougie, tomy. the fize of whice he gradually augmented. After becoming firft a fimple member, and then a 4. He fimplified, and rendered more commodious, the counfellor, of the perpetual committee of the academy redutflon of luxations of tlie humerus of furgery, he was appointed chief furgeon to the hof- 1;. Fatal experience having pointed out the danger of pital of the college, and confulting furgeon to that of employing the trepan in wounds of the head, he fubfti- St Sulpice : neither of thefe added any thing to his tuted another method of treatment (I' itfage de V cine- fortune, but they gave him a clear infight into practice, t'lque) now adopfcd by many praflltioners. and enabled him to judge of cafes by the indudtions 6. He made feveral very ufeful improvements on chl- arifing from his own experience. rurgical inllruments ; fuch as tliofe. employed in the cafes (a) The hufinefs of the day was condufted in the following routine ; i. A public confultation concerning, the indigent out-patients. 2. The young praftitloners belonging to the hofpital read a detailed account of all the interefting cafes of fuch patients as were to be difcharged that day. 3. The operations : each of thefe was preceded by a differtation on the flate of the patient, who was then carried to the amphitheatre, where Default, attended by his afliftants, performed the operation in prefence of all the pupils. 4. Argumentative details, by the profefTor, either on the dangerous maladies exifting in the hofpital, or on the fituation of the patients on. whom operations had been performed during the preceding day. 5. The diifeftion of fubjefts. And, 6. A ■fcfture on fame particular branch of pathology. D E S \ 488 ] D E T Def-uU. cafL'S of polypus in the womb and noftrils f/a p'mce a gai'nc et des pcrte-tia-jds pour hi ligature da polypes, &c. ;) for cutting through obftruftions in the different cavi- ties (/f tlctome) ; and for theji/lula in arto. In cafes of incifion he introduced the ufe oF the inllrument {le gor- gerct) invented by Marciietti, well known among fo- reigncrs, but almoil totally negledled in France before this period. He at the fame time retrenched the ufe of a great number of fuperfluous ones, and banifhed all pradlices attended with greater pain than utility. Avoiding eve- ry thing that was complex, he proved that the art of healing, in imitation of nature, ought to be fimple in Its means, and fruitful in its refources. In 1791 he publifhed his Journal de Chirurgerie, ■which was edited by his pupils, and deftined to defcribe the moll interefting occurrences in his fchool, and alfo extraAs from his leAures, which were then dedicated to the inveftigation of the maladies incident to the uri- nary paffages. The treatment of thefe difeafes, hither- to the reproach of practitioners, had been much impro- ved by the affiftance of the artift Bernard. The elaftic ■probes (les fandes elajliques), on their firft appearance, fixed the attention of all profefTional men ; but none knew better than Default how to appretiate their ad- %aiitages By means of them, he introduced a novel mode of cure in contraftions of the urethra, which faved a great number of lives every year in the Hotel- Disu. But he did not confine their ufe to the difeafes of the urethra alone, for he employed them to remove the di- vers obftacles that impede deglutition or refpiration. In the midft of fuch a multiplicity of labours, and although he was obliged to attend 400 fick twice a- day, Default neverthelefs employed more than four hours of his time in vifiting private patients. Few furgeons ever enjoyed fuch an exclufive fhare of public confidence ; few ever pofTefTed fimilar means of enriching themfelves ; and yet he neglefled for a long time to take advantage of this. Had he been lefs ar- dent for glory, he would have been more favoured by fortune ; but he facrificed all interefled views to the noble ambition of advancing his art. His clinical and anatomical courfes were gratuitoufly opened by him to the world after the year 1790; and while the public fchools languifhed in the midfl of troubles, infeparable perhaps from a miglrty revolution, he was forming the greater part of thofe furgeons employed at this prefent moment in the numerous armies of the republic. Con- iidered under this point of view alone, the fervices which he rendered to humanity are incalculable : too happy if perfecution had not been his fole reward ! While out of mere attachment to the public weal, he added to his various funftions that of a member of the council of health, conferred on him in 1792 by the minifter Servan, lie was denounced in the popular focie- tics as an egotijl., an indifferent, &c. and became one of the firil viftims of that profcription which, under Robe- fpierre, extended to nearly every man of talents. Chaumctte accufed him to the feftions as having ne glefted the brave men wounded on the loth of .\uguft, while they themfelves were lavifhing their blefllngs at the Hotel Dieu on their faviour. Twice was he brought to the bar of a commune ; defirous of difcovering a pre- text for perfecution, the clamours of the, people were unremittingly excited againft him. He was at length Hefault, carried away from his amphitheatre, while in the very Ut^ttrnii aA of haranguing his pupils ; and, in confequtnce of a , ^" mandft d'arr t from the revolutionary committee, con- dufted by a body of armed men to the Luxembourg. From this horrid prifon few ever departed but to meet their fate ; luckily, however, his name was not yet en- tered on that bloody lift, iu which thofe of Makfherbes and LavoiJier were inferted. On the contrary, at the end of three days he was liberated, and inilaatly retu- rned all his funftions. On the eftablifhraent of L'Ecolede Sante, Default was appointed clinical profeflbr ; and for external mala- dies he foon after obtained from the government the convertion of the Eveche into an hufpital for furgical operations. In the midft of thefe plans, the troubles that occur, red in the munth of May unfortunately affefted his mind, and made him dread left the days of profcription (liould return. It was in vain that his friends attempted to foothe his fufferings ; for on the night of the 29th. of May, a malignant fever made its appearance, and a nearly continual delirium enfued until his death, which occurred on the ift of June 1795. on which day he breathed his laft, in the arms of his pupils, at the age of 51. The populace were perfuaded that he was poifoned. This ridiculous opiiuon originated in confequence of the epoch of his death, which preceded but a fhort time that of the fon of Louis XVI. whom he had vitlted during his ilinefs in the prifon of the Temple. It is pretended that he fell a vidlim to his conflant refufal to yield to the criminal views entertained againft the life of that child. Default was of a middling ftature. He was well pro- portioned, and pofTcffed an open countenance. His temperament, naturally robuft, had been fortified by his early education, and was never tapped by an excels of pleafures, for to them his heart was always indifferent. His ruling paflion was the love of glory ; his favourite purfuit, the praflice and advancement of his art. He was warm, nay fometimes violent; and his fcholars were not always inclined to praife the fweetnefs of his tem- per. On the other hand, his mind was noble, elevated, and great, even to excefs. The French republic, eager to pay homage to his memory, has prefented his widow with a penfion of 2,000 livres^fr annum. A fon, Alexis Mathias Default, was the fole fruit of his marriage ; and he has left but one work behind him, in which the name of his friend Cho- part is joined with his own. It Is entitled Traile dei Maladies Chirurgicales et des Operations qui leur convien- nent, 2 vols '^vo. DETERMINATE problem, is that which has but one folutlon, or a certain limited number of folu- tions ; in contradiftinftion to an indeterminate problem, which admits of infinite lolutions. D-TfRMiN^TB SeSion, the name of a traft or general problem, written by the ancient geometrician ApoUo- nius. None of this work has come down to us, ex- cepting fome extrafts and an account of it by Pappus, in the Preface to the 7th book of his Mathematical Colleftions. He there fays that the general problem was. " To cut an infinite right line in one point fo, that, of the fegments contained between the point of fedion D E T (eftion fouglit, and given points in tht faid line, the I'quare on one 3 R . , , of thern, ov the rectangle contained by two of them, may liave a given ratio, cither to the rcftangle contained by one of them and a given line, or to the rciftangle contained by two of them." DETONATION (fee that word Enrycl.). The aftonilliing violence with which the oxy-niiiriat of pot- afs, when mixed with various fubllances, detonates, has been already noticed in this Supplement under the ar- ticle Chemistry, n" 112, where the theory of th':fe explofions is likewife given. But as fcveral chemills teem to think that this fait, which decrepitates by fric- tion, and fpontaneoufly takes fire when mixed with ful- phur, contains in itfclf the elements and phenomena of thunder, it will not probably be unacceptable to our readers to find, in this place, a diftinc^ account ot the various mixtures which produce its detonations. The following are the principal which have been difcovercd by Fourcroy and Vauquelin. 1. Three parts of the oxy-muriat of potafs, and one part of powdered fulphur, rubbed together in a metal mortar, produce numerous fucceffive explolions, refem- bling the fmacking of a whip, or even as loud as the re- port of a piftol or a tTiufl be concealed under it. Whilit tiie will. mean- ing divine was fupporting, by the bed arguments which he could devife, the religion of his country, Diderot and D'Alenibert were overturning thofe ari^uments un- der titles which properly allowed of no fueh dif(]uiri- tions. This neceiVarily produced digrefiions ; for the greateft genius on earth could not, when writing on the laws of motion, attack the myfteries of Chriilianity without wandering from his fubjcft ; but that the ob- jeft of thefe digrefTions might not pafs unnoticed by any clafs of readers, care was taken to refer to them from the articles where the queftion was difcuffed by the divine. That when employed in this way, DIdenjt feems to write obfcurely, is indeed true ; but the ob- fcurity is not his. Hi« atheifm was fo plain, that for the moft part D'Alembert, or fome other leader of the gang, had to retouch his articles, and throw a mift over them, to render their intejition the lefs obvious. Even with all this care and ftudied obfcurity, the de- fign of the Encyclopedic was too palpable not to be feen, and too wicked not to give offence. Certain wild po- fitions on government and on religion occafioned the imprcflion to be fufpended In 1752. At that time there were no more than two volumes of the dictionary publiflied ; and the prohibition of the lucceeding ones was only taken off at the end of 1753. Five new vo- lumes then fuccelfively appeared. But in 1757 a new dorm arofe, and the book was fupprelTed. The re- mainder did not appear till about ten years after ; and was then for a while only privately dillributed ; fome copies having been feized by government, and the prin- ters fhul up in the Baftile The merit, however, of fome of the articles is confefledly great; and the firft edition was quickly fold off Thus was this great work in the prefs from 1751 to 1767 ; during which period, Diderot and D'Alembert were accuftomed to frequent the coffeehoufes of Paris, and to enter with keennefs into religious difputes : the former attacking Chriftianity ; and the latter, under the mafic of piety, defending it ; but always yielding to the arguments of his opponent. This praftice was put a rtop to by the police ; and Diderot, when reproached by the lieutenant with preaching atheifm, replied, " Ce- la eft vrai, je fuis athee, & m'en fais gloire." Finding his impiuus converfations interrupted, and the publication of the Encyclopedic rendered tedious by the vigilance of government, he thought of propaga- ting his notions by other vehicles. Alternately ferious and fportive, folid and frivolous, he publiflied, at the very time he was working on the Dictionary of Scien- ces, feveral produftions, which could fcarcely have been expedled from a man fo completely employed. His Bijoux Indifcrets, 2 vols izmo, are of this number — a dilgufting work, even to thofe young people who are unhappily too eager for following after licentious ro- mances. Even here a certain pliilofophical pedantry appears in the very pafTages where it is moil mifplaced, and never is the author more aukward than where he intends to diiplay a graceful eafe. The Fils Naturel, and the Pere de Famille, two come- dies in profe, which appeared in 17,-7 and 1758, are not of the fame kind with the Bijoux ludifcrels. They are moral and affe£ling dramas, where we fee at once a ner- Tous ftyle and pathetic fentiments. The former piece r 491 1 D I D is a piclure of the trials of virtue, a confliifV betwten in- I'i'lf'ef. tereds and pafTions, wherein love and friendfliip play *— ^/— ~ important parts. It has been faid that Diderot bor- rowed it from Goldoni : but if that be the cafe, th; copy does honour to the original ; and, with the ex- ception of a fuiall number of fcenes, where the author mixes hia philofophical jargon with the fentiments of the heart, and fome fentcnces out of place, the flyle is afrefting and natural enough. In the fecond comedy, a tender, virtuous, and humane father appears, whofe tranquillity is dillurbed by the parental folicitudes, iu- fpired by the lively and impetuous pafTiojis of his chil- dren. This philofophical, moral, and almoft tragical comedy, has produced confiderablc effctls im feveral theatres of Europe. The dedication, to the princcfs of NaiTau Saarbuck, is a little moral traft of a lingular turn, without deviating from nature. This piece, writ- ten with a true dignity of ftyle, proves that the auth.ir pofTefTed a great fund of inoral fentinients and philofo- phical ideas. At the end of thefe two pieces, publilli- ed together under tlie title of Theatre de M. Dideiui, are dialogues, containing profound refledlions and novel views of the dramatic art. In his plays he has endea- voured to unite the charaders of Ariftophanes and Pla- to ; and in his refledions he fometimes difplayj the ge-' nius of Ariftotle. This fpirit of criticifm is exhibited, but with too much licence, in two other works, which made a great noife. The former appeared in 1749, izmo, intitled Letters on the Blind for the Ufe of thofe who See. Tiii free notions of the author in this work coft him his li- berty. He underwent a fix months imprilonment at Viorcennes. Having naturally ftrong palTions and a hauglity fpirit, and hnding himfelf on a fudden depri- ved d differences C, C% C, &c. the third difleren- ccs D, DN D', &c. and fo on. Then if T ttand for the firft term of the nth That is, B^3-A, C = c—2b-\.A, D = + \, &c. or -Br: A— i, J^^];^^ + C = A—2b+c, —D = A—^i + ^c—d, +E = A '"""^ — 4i-|-5f — 4'/-<-'', Sec. where, putting T fuccellively equal to B, C, D, E, &c. and nzzi, 2, 3, 4, &c. the prop, will be evident. Cor. Hence A=:A, the firft term. B = — A-|-^, the firft difference. C = A— zli + c, the 2d dift'ercnce. D = — A-f 3* — 3r-f-(/, the 3d difference. E =r A — 4ii-j-6c — 4^-|-<', tlie 4th difference. F = — A-f-ji — loc+iod — Jc-J-/, the 5th difference, &c. PkOp. II. If A, i, c, d, e, &c. be any feries, a*"^ there be taken B, C, D, E, &c. the firft of the fever^^ orders of differences ; Then, the nth term of the feries will be ;= A differences, :±zT:=A — » 3 -f- n X d + nx' n - I n — 2 Ix"- 2 n — -nX- n — I 2 h — &c. that 3 .2 3 4 is, -j- T, when n is even, and — T when n is odd. Tlte feveral orders of differences being taken as be- fore dirtifted, will ftand thus. Then, ^ B ' B3 °^ '^ B4 &c. feries ift diff. 2d diff. 3d diff. 4th diff. » -A + - , c , a , e, Sec, c — b , d — c , e — d, &c. c — 2i-|-A, d — 2c-\-b, e — zd-\-c. Sec. d—2c+ib—A,e—3d+ic—b, &c, f— 4(/+6f— 44+A, &c. I n - -B + - 2 n — I 1 -c + — -X- n — I „n — 2 x^r:-^x!L=i4E+,&c. 2 «--9 — X — - 3 ' 2 3 . 4 For from the equations in the laft Prop, viz B =: i — A,C=c — zi-i-A, &c. we have, by tranfpofing, i=A-j-B, =— A-(-2y-f-C= — A + 2A-f 2B + C (expunging b^ ; that is, c=A-l-2B-f-C, , d"i, &c. he the firft of the f.ift, fe. cond, third order, &;c. of differences ; then The nth term of the feries A, b, c, d, &c. will be n — i„ n — I n — 2 n — i n — 2 = A-i- -—e king to feize both the fhip and the cargo, Jew, who had fludied under Leibnitz, informed the under a pretence that Phipps, when he follcited for his German editor, that he well knew that Ditton and majefty's permifficn, had not given accurate information Leibnitz had correfponded upon the fubjeft ; and that refpeding the bufinefs. But the king anfwered, with Ditton had fent to Leibnitz a delineation of a machine much greatnefs of mind, that he knew Phipps to be an he had iiivented for that purpofe; which was a piece of honeil man, and that he and his friends Ihould fhare the roechanifm conftrucled with many wheels like a clock, whole among them had he returned with double the and which Leibnitz highly approved of for land ufe ; value. His majefty even conferred upon him the ho- hut doubled whether it would anfwer on fhip-board, on nour of knighthood, to (hew how much he was fatisfied account of the motion of the (liip. with his conduft. We know not the conitruftion of DIVING-Bell has been already defcribed in the Phipps's apparatus : but of the old figures of a diving- Encychpa-iiia ; but in that work was given no account machine, that which approaches nearell to the diving. of its antiquity or its invention. In the works of Ari- bell is in a book on fortification by Lorini ; who de- llotle we read of a kind of kettle ufed by divers to ena- ble them to remain for fome time under water ; but the manner in which ihofe kettles were employed Is not clearly defcribed. " The oldeil information (faysPro- feifor Beckmann) which we have of the ufe of the di- ving bell in Europe, is that of John Talfiiier, who was born at Hainault in r 509, had a place at court under Charles V. whom he attended on his voyage to Africa. He relates in what manner he faw at Toledo, in the fcribes a fquare box bound round with iron, whirli is funilhed with windows, and has a ftool af[i>;ed to it for the diver. This ingenious contrivance appears, how. ever, to be older than that Italian ; at kail he does not pretend to be the inventor of it. In the year 1617, Francis Kefsler gave a defcriptioa of his water-armour, intended alfo for diving, but which cannot really be ufed for that purpofe. In tlie year 1671, WItfen taught, in a better manner than any of pretence of the emperor and feveral thoufand fpeftators, his predcceflbrs, the coTiftrudion and ufe of the di two Greeks let themfelves down under water, in a large ving-bell ; but he is much miftaken when he fays that inverted kettle, with a burning light, and rife up again it was invented at Amllerdam. In 1679 appeared, without being wet. It appears that this art was then new for the firil time, Borelli's well known work ^t mor/;* to the emperor and the Spaniards, and that the Greeks anhnatium ; in which he not only defcribed the divlnir- were canfed to make the experiment in order to prove bell, but alfo piopofed another, the impraiticability the poflibllity of it." of which was ihewn by James Bernoulli. When When the Englilh, in 1588, difperfed the Spanifh Sturm publifiicd his Colleg'mm cur'wfum in 1678, he fleet, called the Invincible Armada, part of the ihips propofed fome hints for the improvement of this ma- went to the bottom, near the Ifle of Mull, on the well- chine, on which remarks were made in the Journal frn coaft of Scotland ; and fome of thefe, according to des f^avans. To him fucceeded Dr Halley, whofe bell the account of the Spaniih prifoners, contained great is well known. riches. This information excited, from time to time, DODECATEMORY, the 12 houfes or parts of the avarice of fpeculators, and gave rile to feveral at- the zodiac of the pri{num mobile. Alfo the 1 2 figns tempts to procure part of the loft treafure. In the of the zodiac are fometimes fo called, becaufe they coa- year 1665, a perfon was fo fortunate as to bring up tain each the J2th pai-t of the zodiac. fome cannon, which, however, were not fufficient to DOME. Sec Arch in this Supplement. DOMINGO, Diving. Bell II ' Doiiie. Unmingo, Oon. DON [ DOMINGO, or St Domingo. See Hispanioiia, both in Encycl. and in this Supplement. DON Martin de Mayorga, the name given by the Spaniards to a cluilcr of 'iflaiids in the South Sea, difcovered on the 27th of February 1781 by Don F. A. Maurelle, a celebrated pilot of that nation. Thofe iflands are defcribed by him as abounding with tropical fruits and roots, as highly cultivated, and as inhabited by a people confiderably poliflied. The fer- tility of the land, fays he, is fuch, that its cultivation cannot fail to promife a favourable harveft. Every where are feen an endlefs number of cocoa-nut trees, beautiful banana trees ranged in lines with the greateft order, and numerous plantations of potatoes, of which he deferibes fome as fifteen feet in length, and of the thicKnefs of a man's thigh. He admired the order with which every thing was difpofed. No weeds were fuf- fered to grow between the plants; and their roads were kept in repair with a diligence deferving imitation by the mod civilized nations. Their government appears from his account to be defpotic. The fovereign, who is called the Tubou, is held in the higheft veneration by his fubjefts, vvhofe Ijves and propeities are at his difpofal. Under him there is an order of nobles called Equis, who, though they flirlnk into inf;j^nificauce in the prefence of the Tubou, have great authority over the people. Thefe people are faid by Maurelle to be of great mufcular Arength and large ilature, the ordinary height of the men being fix feet or fix 'feet four inches, while many of them are much taller. It would appear, too, that they delight in gymnaftic exercifes ; for when the 7u- ■boil, by whom he had been treated with great liofpita- lity, wifhed to amufe him and his {hip's coinpaiiy, he exhibited to them feats of vvreiUing and boxir.g, and that as well by the women as by the men. Though thefe people put the greateft confidence in the Spaniards, and frequently Raid whole nights on board the frigate, they had yet the common iuch'nation of favages to fteal. " Every time they came on board (fays our author), clothes, iron-work, whatever fell in their way, they confidered as lawful prize. They drew out through tlie port-holes, or the windows, whatever was within their reach. They thieved even to the very chain of the rudder. I made my complaints to the king; he gave me permiffion to kill whomfoever I fhould deteft in the aft ; and 1 was alfmed he had himfelf dif- covered and punifhed with deatli the authors of the complained of theft. Our vigilance was neceflarily cal- led into atlion ; we furprifed the iflands.'rs ftriving to tear away the new rudder chains ; we fired a piftol at them, one of them fell dead on the occafion, and this was an awful leflon for thofe who were either tvi """V^—^bed under the liril clafs. He therefore determined to forming two fides of a trough of peat ; then fide ftonts^~~v~ attempt the cure in the manner before prdcribed for about eight inches high, and a Hone coverer, were put that clafs, namely, to cut through the whole of the lira- in upon the ling between the peat- turfs ; a large peat- turn (in this inftance, of quick-fand), through which turf, near two feet wide and four inches thick, was he found the waiter pafs. This he etfefted as follows : then cut and firmly placed over the whole : this left in The fummer being dry, and favourable for the purpofe, the bottom of the drain an open fpace, of more than and having previoully made his main open drain, he began fix inches fquare, for the water to pafs. The whole his main clofe drain the tirll week in June 1791, three was then completed by tilling in the upper part of the feet wide, on the declivity near the edge of the great drain. bog. In the firll operation he dug through the peat. In this way the author drained, for about L. 80, the hard fand, and gravel, and one fpade's graft (about thirty acres of land, which, from being of no value nine inches detp, and feven inches wide) into the quick- whatever, became worth at leaft 14 (hillings per acre of fand the whole length of this drain, which was 73 yearly rent. He likcwife hollow-drained nine acres by perches, of eight yards to the perch, in length. The the method prefcribed for the third clafs of wet land, drain thus dug ran copioufly, not lefs than 60 gallons Theie diaiiis were made a few yards below that part of per minute. In this ftate he left it about nine d;iys : each field where the dry and wet land feparate, about the effeft of it was rapid, both above the drain and on 22 inches deep, with fides and a coverer of llone, and the bog below. Upon examination, he now found about ling on the top of it, to keep the earth from running three inches on the top of the fpade's graft, which had in. The length of thefe drains was 88 J yards, and the been made into the quick-fand perfeftly dry. He then expence of labour and materials three halfpence per dug out thefe three inches of dry fand, to nearly the yard. The drains, in wet weatlier, difcharge a large whole width of the drain, three feet ; and at the fame quaitity of water ; and will, he has no doubt, anfwer time dug out, as before, another fpade's graft from the the intended purpofe. Thus far relates to land in his top of the quick-fand, as near the middle of the drain own occupation. as poffible. This was left to run a few days, as before. Nine acres of the land in the earl of Aylesford's occu- and had the fame effeft, namely, three or four inches pation was almoft an entire pulp. This bog was of the more of the top of the quick-fand became dry and hard, fecond clafs, namely, water paffing through a quick- The fame operation was repeated again and again with fand, and confined by a llratum of clay below, and ano- the fame efteft, till the purpofe of getting through this ther ftratum of clay above it. The water thus coii- quick-fand was completed, fo far at leaft as the level of fined, being preiTed by its fountain, and forced up thro' the main open drain would permit. The ftream of wa- the weakeil parts of the clay, had formed a bog of ir- ter continued increafing during the whole operation ; regular thicknefs on the furface, in fome places fix feet the bog below the drain was quite dry, and the land deep, in others not more than two. As there is a con- above perfeftly fo. The drain which was firft made, fiderable fall in this land from eaft to weft, he thought and continued running for fome time during the. pro- it expedient to put two drains into it ; and this appears grefs of the main clofe drain, became gradually dry ; to him to have been neceffary, from a confideration that and has not, fince that drain was finifted, difchargcd both thefe drains continue to run in the fame propor- one fingle drop of water. Great care was neceffary, in tions as when firll opened. The manner in which theie making the main clofe drain, to keep the ftream of wa- drains were executed was, by digging through the dif- ter in the middle of it, otherwife the current would have ferent upper ftrata, and as deep into the clay as the undermined tlie fides, as it fometimes had done, and main open drain would admit ; then digging or boring caufed them to fall in. For this reafon it was necef- through the remaining part of that clay into the quick- fary, when the dry fand was taken from the top of the- fand, at the diftance ot about fix yards in a progrefiive quick-fand, immediately to take out a fpade's graft from r/ianner. the middle thereof, in order to divert the current from The water rifing rapidly through thefe holes into the the fides. clofe drains, has cifected a complete cure of this land. The main clofe drain thus made was three feet wide every part of which will now bear a hoife to gallop at top, about nine feet deep on the average, and, bevel- upon it. Thefe drains difcharge 3660 gallons an hour ; iing a little from the top, it was about one foot ten which is much lefs than they did at firll, as mull be the inches wide at the bottom. The ftone and other ma- cafe in all bogs. This "nind will be worth twenty fliil- terials were put into this drain in the following manner : lings per acre. The draining coft twfenty-five pounds ; Where the drain went through the quick-fand into and the length of the under-ground drains is eight hun- the ftratum of clay below it, as in moft places it did, dred and fourteen yards. the bottom, and in fome inftances the fides, wanted no Mr Wedge had juft finifhed (January 1792) drain- particular fecurity (a); but where it did not go quite iiig another piece of land, about forty-three acres. As through the quick-fand, which the level of his main this was intended to anfwer two purpofes, one, to draiii open drain in fome places would not admit, the bottom the land, the other, to give an additional fupply of wa- of the drain was covered half an inch thick with ling ; ter to a mill-pool, and as a circumftance arofe in the then peat-turfs, one foot wide and three or four inches execution of the work which frequently happens in tliick, were cut in convenient lengths, and placed on draining land, namely, a fudden alteration in the po- fitiou (a) He will probably find in time that he was under the fame miftake with Mr Bayley, and we hope that with Mr Bayley's candour he will acknowledge it. D R fition of tlie under (Irala not, we hope, be thought tedious. This dlaiiiing was begun at the level of a mill-pool, and continued, with- out any great difficulty, to tiie dillame of about thirty- two chains, in the manner before defcribtd as a cure for the fecond clafs of boggy land : but at or near that place the under ftrata altered their pufition ; the quick- fand which conveyed the water now became of twice its former thicknels ; and the clay, which had hitherto been above that quick fand, for fonie diftance difap- peajed. From the quick-fund thus becoming- fo much deeper, he could not, witli the level of the null-pool, cut through it ; nor indeed, from the wctnefs of the ftafon, would fuch an operation have been proper. He therefore continued a (hallow drain to fonie diftance, making fide-holes into the quick-fand, which lan freely; but as this could not cure the whole of the bog below, lie branched out another drain ^which was made by the method dcfciibed for curing the fecund clafs of wet or boggy land), by finking a dofe drain through the up- ]ier Itrata into the upper clay, and then, at a fmall dif- tance on one fide of this clofe drain, boring a hole with O [ 499 ] . .^ . '^^ A •a defcrijition tliercof will (aa quoted by Withering, in hia Arrangement of BrI- DMigi tilh Plants,) mentions the cflcfts of this finguhir plant, H . occafioned by the irritation of an aiit, which he placed ,"""""^. on the centre of one of the leaves with a p?ir of pincers. ' The ant, in endeavouring toefcape, was held fad by the vifcous juice of the Imalkr hairs till the large ones, together with the edges of the leaf, clofed in and im- prifoncd it. The ant died in fifteen minutes ; but he obferves, that the effefts followed fooner or later, in dif- ferent experiments, according to tiie Hate of the wea- ther. Dr Whithering has publidicd a fimilar accoiuit of the fenfitive propeities of the fundew, which was com- municated to him by two of his botanical friends, and which he has made very entertaining and interelling. The fame thing is confirmed by a writer in tlie Month- ly Magazine for Augull 1797 > "■''" %**, that when- ever he made experiments on the drofitra with aiita and other diminutive infefts, he commonly found them perifli in a Ihorter time than fifteen minutes. His experiments' were made on the droflera rotundifolia. Rothius, how. ever, obferves, that the longifolia produces the fame ef- feAs, but with greater rapidity. In concluding his ac- n a'lger through the remaining part of that clay into count, Dr Withering fuggells this enquiry, " Whether the quick-fand ; and at every eight yards, as this clofe drain advanced, flill boring other holes, in the manner before dcfcribed : through many of thefe holes the wa- ter rufhed with great rapidity. The water difcharged by thtfe drains into the mill-pool is 168 gallons per mi- nute, or 3780 hogfheads in a day ; which is after the rate of 1,379,700 hoglheads in a year. About fix acres of this land were always found ; a- bout twelve acres on the north fide were an abfolute pnlpj and the remaining twenty fix acres very unfound. The whole is now found, and will, when cultivated, be worth fixtcen fhillings per acre. This land would have been drained at a much lefs cxpence into the main open drain ; but then the water, which was much wanted for the mill, would have been loft.. Thefe clofe drains are in length 1452 yards, and coft L. 100, of which about L. 30 ought to be charged to the mill. Important as this fubjeft is, we inull not enlarge this article, or we ihould make large extrafts from Dr An- dcrfon's PraB'ual Trealife on Draining Bogs and Siuam- py Grounds, lately publilTicd. It is proper, however, to inform the public, that the author puts In his claim for being the firft difcoverer of that mode of draining for which Mr Elkington has obtained from Parliament a premium of L. 1000 ; and the reader who (liall turn to the article Drains in the Encyclopa:dia, will per- ceive that his claim is well-founded. DROSSERA Anglicana, or the Sundew (fee Drossera, EncycL), is a very minute villous plant, ufually growing entangled with mofs on peat bogs ; the leaves are cuiioully fringed with numerous ftrong red- difh hairs, terminated by fmall pellucid globules of vif- cous liquor, which occafion, by the refledlion of the fun, thr.t peculiar lufl^re from which its name Is derived. this deftrudllon of infefts be not neceffary to the welfare of the plant ?" And it is furely worth fome botanilt'g while to take fome pains to anfwer the queftion. DRUGS (fee Encycl.) are fo commonly counter- feited, or at lead adulterated, that, in London, the royal college of phyficians, it is well known, has long ago appointed a court of examiners to inveiligate the goodncfs of drugs and medicines in the different che- inlfts and apothecaries (liops. The coujitcrftit, how- ever, is made up with fuch dexterity, that not only the merchaot and drug-broker, but even the man of (kill, Is fomeilnies deceived ; and indeed nothing can deleft this inipo(itlon but a practical knowledge of chemlllry. Wc therefore recommend it to every father of a family to ftudy our Supplementary article Chemistry with this view, if with no other ; for wliatevcr be the faults or that atricle, we have loll much labour if it be not fuHi- ciently perfplcuous to enable every man, not an abfo- lute ftranger to phyfical fcience in all its branches, to detei;t the common impollures of drug- fellers. DUFTER, in Bengal, an otHce or departme^it. DuFTSR Catici, the place where the office is kept. DWARFING OF vegetables, an art invented by the Chinefe, to which the attention of Sir George Staunton was attrafted on the following occafion : When the embalfy was at Chafan (See Chusan in this Supplement), the gentlemen who went on (hore were introduced to the governor in his hall of audience, where on feveral tables were placed, in frames filled with earth, dwarf pines, oaks, and orange trees, bear- ing fruit. None of them exceeded in height two feet. Some of thofe dwarfs bore all the marks of decay from age : and upon the furface of the foil were iiiterfperfed fmall heaps of ftones, which, in proportion to the ad- It is in thefe hairs that thefe effential properties of the joining dwarfs, might be termed rocks. Thefe were plant refide ; for if a fmall infeft fhould fix itfclf on one of the leaves, thefe hairs immediately begin to clofe, one by one, till the Infeft is wholly environed by them, and then the leaf in which it is imprlfoned gradually bends inwards, fo as to reach the bafe : in this ftate the infeft is killed by the operation of the acrimonious juice exuding from the ends of the hairs. Rothius honey-combed and mofs-grown, as if untouclied foo- ages, which ferved to maintain the illufioTi, and to give an antique appearance to the whole. This kind of ftunted vegetation leemed to be much rchfiied by the curious in China j and fpecimens of it were to be found in every coufiderable dwelling. To produce them form- ed a part of the gardener's (Icill, and was an art invented 3 R a in D W A t 5 DAirEng. in that country. Bifjde the mere tnerit of overcoming /""' a d.'fEciilty, it had that of introducing vegetables into common apartments, from which their natural fize mufl cthevwife have excluded them. The jrencral method of obtaining vegetable dwarfs is faid to he the following : A quantity of clay or mould is applied to the upper part of the trunk of a tree, from which a dwarf is intended to be taken, and clofe to its divifion into branches. The mould is to be confined to the fpot by coarfe hempen or cotton cloth, and to be carefully kept moid by water. In confequence of this application, continued fometimes above a twelvemonth, fmall tender fibres (hoot down like roots from the wood into the mould. The part of the trunk emitting thofe new fibres, together with the branch rifing immediately above it, is then to be carefully fcparated frr-Ki the reft, of the tree, and planted in new earth, in which the fibres become new roots, while the former branch is now the ftem of the vegetable thus transformed in fome meafure. This operation does not deftroy or alter the produftive faculty which thofe parts enjoyed before their Reparation from their parent root. That which, while a branch of the original tree, bore flowers and fruit, con- tinues to produce the fame, though no longer fupport- ed upon any ftock. The terminal buds of fuch branches of trees as are meant to become dwarfs are torn off ; which circumftance prevents the further elongation of thofe branches, and forces other buds and branchlets from the fides. Thefe branchlets are bent by wires to 00 ] DYE whatever form the operator wifhes : and when the ap- pearance cf age and decay is meant to be given to a dwarf tree, it is repeatedly fmeared with treacle or mo- lafies, which attrafts multitudes of ants, who, in pur- fuit of thofe fweet juices, attack the bark, and, by a gradual corrofion of it, produce the defired effefl. Thefe different proccffes are fornetimcs attempted to be kept fccret by the gardeners, and they vary defignedly in the mode of carrying them on; but the principle on which they are founde^d is fufficiently apparent from what is related here ; and the contrivance argues ingenuity and perfcverance, rather than the praftice does true tafte, which confifts in affifting Nature in its moil favourite works — not in counterafting its operations or diftort- ing its produflions. DYEING is an art into which, fince the article in the Encyclopaedia was publilhed, improvements have been introduced of fuch importance, that it would be unpardonable not to notice them in this Supplement. They ought to be noticed under the prefent title ; but, for reafons affigned at the time, we were under the ne- ceflity of poftponing them, in the firll edition, to the title Vegetable, /Inimal, and Dyeing Substances. We might now rettore the article Dyeing to its proper place ; but though we confidently announce this as an improved edition, we doubt whether we can, in juftice to the purchafers of the firfl edition, alter its arrange- ment. We therefore ftill refer the reader to the article Dyeing Substances, Hyeing, DYNAMICS. Definition. Objefl f)f dynamics i change of that cond> tion of a thing which we call its ino- THIS name marks that department of phyfico-ma- thematical fcience which contains the abftraft doftrine of moving forces ; that is, whatever necef. farily refults from the relations of our ideas of motion, and of the immediate caufcs of its production and changes. All changes of motion are confidered by us as the In- sdications, the charafteriftics, and the meafures of chan- ging caufes. This is a phyfical law of human thought, and therefore a principle to which we may refer, and from which we muft derive all our knowledge of thofe caufes. When we appeal to our own thoughts or feel- ings, we do not find in ourfelves any difpofition to refer mere exillence to any cauie, although the beginning of exiftence certainly produces this reference in an inftant. Kad we always obferved the univerfe in motion, it does not appear that we fhould have afcribcd it to a caufe, till the obfervation of relative reft, or fomething leading to it, had enabled us to feparate, by abftraftion, the notion of matter from that of motion. We might then perceive, that reft is not incompatible with matter ; and we might even obferve, by means of relative motions, that abfolute reft might be produced by the concourfe of equal and oppofite motions. But all this requires refietlion and reafoning ; whereas we are now fpeaking of the firft fuggeif ions of our minds. We cannot have any notion of motion In abJlraSo, without confideriiig it as a ilate or condition of exiftence, which would remain, if not changed by fome caufe. It is from changes alone, therefore, that we infer any agen- cy in nature ; and it is in tUefe that we are to find all that we know of their caufes. When we look around us, we cannot but obferve jvrechanie that the motions of bodies have, in moft cafes, if not relation, always, fome relation to the fituation, the diftance, and what, the difcriminating qualities of other bodies. The mo- tions of the moon have a palpable relation to the earth; the motions of the tides have as evident a relation to the moon ; the motions of a piece of iron have a palpable dependence on a magnet. The vicinity of the one feeras to be the occafion, at leaft, of the motions of the other. The caufes of thefe motions have an evident conneftion with or dependence on the other body. We are even difpofed to imagine, that they are inherent in that body, and that it poireffes certain qualities which are the caufes of thofe modifications of motion in other bodies. Thefe ferve to diftinguifh fome bodies from others, and may therefore be called properties ; and, fince the condition of other bodies fo evidently depends on them, thefe properties exprefs very interefting rela- tions of bodies, and are chiefly attended to in the enu- meration of the circumilances which afcertain what we call the nature of any thing. We do not mean to fay that thefe inferences are always juft; nay, we know that many of them are ill-founded : but they are real, and they ferve abundantly for informing us what we may expeft from any propofed fituation of things. It is enough for us to know, that when a piece of iron is fo and fo fituated in relation to a magnet, it will move in a certain manner. This mutual relation of bodies is differently confider- ed, according to the intereft that we chance to take in the phenomenon. The caufe of the approach of the iron to a magnet is generally afcvibed to the magnet, which D Y N A vihkh is faid to attraft the iron, becaufe we commonly employ the magnet in order that thefe motions may take place. Tlie limilar approach of a Hone to the earth is afcribcd to the ftone, and we fay that it tends to the earth. In all probability, the procedure of na- ture is the fame in both; for they are obferved, in every in (lance, to be mutual between the related bodies. As iron approaches a magnet, fo the magnet approaches the iroji. The fame thing is obferved in the motions of eleftrified bodies ; alfo in the cafe of the ftone and the earth. Therefore the caufe of the motions may be conceived as inherent in either, or in both. Ftne and The qualities thus inherent in bodies, conftituting /laimiTt their mechanical relations, have been called the mecha- Sgurative [j,cal affections of matter. But they are more w-™[^Q^g" commonly named powers or forces; and the event ^lanifin- which indicates their prefence, is confidered as the ef. feft and mark of their agency. The magnet is faid to ACT on the iron, the earth is faid to act on the ftone, and the iron and the ftone are faid to act on the mag- net and on the earth. All this is figurative or metaphorical language. All languages have begun with focial union, and have im- proved along with it. The firft colleftions of words exprefied the moft familiar and the moll interefting no- tions. In the procefs of focial improvement, the num- ber of words did not increafe in the fame proportion with the notions that became interefting and familiar in their turn : for it often happened that relations of certain ideas fo much refembled the relations of certain other ideas, that the word expreffing one of them ferved very well for expreffing the other; becaufe the diflimilar cir- " cumftances of the two cafes prevented all chance of mif- take. Thus we are faid to furmount a difficulty without attaching to the word the notion o{ getting over a lleep 5 hill. Languages are thus filledwith figurative exprefTions. But the »- Power, Force, and Action, are words which muft nalogy is J^gve appeared in the language of the moft fimjile peo- forcc but P'* ' ^''■'^^ufe the notions of perfonal ability, ftrength, in the df- and exertion, are at once the moft familiar and the moft 't&. interefting that can have a place in the human mind. Thefe terms, when ufed in their pure, primitive fenfe, exprefs the notions of the power, force, and adlion of a fentient, aftive, being. , Such a being only is an agent. The exertion of his power or force is (exclu- fively) action : But the relation of caufe and effeft fo much refembles in Its refults the relation between this force and the work performed, that the fame term may be very intelligibly employed for both. Perhaps the only cafe of pure unfigurative aftion is that of the mind on the body. But as this is always with the defign of producing fome change on external bodies, we think only of them; the inftrument or tool is over- looked, and we fay that we aft on the external body. Our real aftion therefore is but the firft movement in a long train of fucceffive events, and is but the remote caufe of tlie interefting event. The refemblance to fuch aftions is very ftrong indeed in many cafes of mechani- cal phenomena. A man throws a ball by the motion Oi his arm. A fpring impels a ball in the fame manner by unbending. Thefe two events refemble each other in every circumftance but the aftion of the mind on the corporeal organ — the reft of it is a train of pure nie- chanifm. In general, becaufe the ultimate refults of the mutual influence of bodies on each other greatly M I C S. joi refemble the ultimate refults of our aftions on bodies, we have not invented appropriated terms, but have con- tented ourfelves with thofe already employed for ex- preffing our own aftions, the exertions of our own powers or forcc.i. The relation of phyfical caufe and effeft is exprefied metaphorically in the words which belong properly to the relation of agent and aftion. This has been attended by the ufual confequences of poverty of language, namely, ambiguity, and fumetimes miftake, both in our refleftions (which are generally carried on by mental difcourfe), our reafonings, and our conclufions. It is neceftary to be on our guard againft fuch miftakes ; for they frequently amount to the confounding of things totally dilferent. Many phi- lofophers of great reputation, on no better foundation than this metaphorical language, have confounded the relations of aftivity and of caufation, and even denied that there is any difference ; and they have affirmed, that there is the fame invariable relation between the determinations of the will and the inducements that prompt them, as there is between any phyfical power and its eff^eft. Otliers have maintained, that the firft mover in the mechanical operations, and indeed through the whole train of any complicated event, is a perci- pient and intending principle in the fame manner as in our aftions. According to thefe philofophers, a particle of gravitating matter perceives its relation to every other particle in the unlverfe, and determines its own motion according to fixed laws, in exaft conformity to its iitu- ation. But the language, and even the aftions ot all men, ftiew that they have a notion of the relation of an agent to the aftion, eafily diilinguiiliable (becaufe all diftinguilli it) from the relation between the phyfical caufe and its eft'eft. The proofs of this faft have been adduced in other parts of the Encyclopajdia Britannica, as, for example, in the article Philosophy, n" 42. and in this Supplement in the article Action. Thefe remarks are not made in this place for any phi- lological purpofe, fuch as the mere improvement of lan- guage ; but becaufe this metaphorical language has af- fefted the doftrines of mechanical philofophy, and has produced a difpute about fome of its firft principles; and. becaufe we find that the only way to decide this dilpute is to avoid, moft fcrupuloufly, all metaphorical language,, though at the expence of much circumlocution.. g When we Ipeak of powers or forces as refiding In a Dirciltion.T body, and the efft6l as produced by tlicir exertion, the*"'' 'Z'' ^"^ body, confidered as poffeffing the power. Is faid to ACT ,„j.||j,J,',ij^ on the other. A magnet is faid to aft on a piece of analugy, iron ; a billiard ball in motion is faid to aft on one that is hit by it : but If we attempt to fix our atten- tion on this aftion,' as diftinft both from the agent and the thing afted on, we find no objeft of contem- plation — the exertion or procedure of nature in produ- cing the effeft does not come under our view. When we /peak of the aftion as diftinft from the agent, we find that it is not the aftion, properly fpeaking, but the aft, that we fpeak of. In like manner, the action of a mechanical power can be conceived only in the ef. feft produced. A man is not faid to aft unlefs he produces fomeAflion effeft. Thought is the aft of the thinking principle ; iiiplies motion of the liinb is the aft of the mind on It. In '•'•i»nR'^; mechanics, alfo, there Is aftion only in fo far as there"'"' "'^"^^ is mechanical effeft produced. I muft aft violently in not aflign. order 50a D Y N A orJer to begin motion on a fll'Jc : I miift exert force, and this force exerted produces motion. I conceive the produftion of motion, in all cafes, as the exertion of force ; but it requires no exertion to continue the motion along the Aide ; I am confcious of none, there- fore I ought to infer that no force is neCeffary for the continuation of any motion. The continuation of mo- tion is not the produftion of any new effetl, but the permanency of an effeft already produced. We in- deed coniiJer motion as the eflctl of an aftion ; but there would be no efFeft if the body were not moving, g Motion is not the aftion, but the effeft of the atlion. Tr/jfion/un. Mechanical aftions have been ufually clafled under fulfun. two heads : they are either Pressures or Impulsions. They are generally coniidcred as of different kinds; the exertions of different powers. Pressure is fuppofed to differ effentially from Impulse. Inllead of attempting to define, or dcfcribe, thefe two kinds of forces and aftions, we (hall juft mention fome inftances. This will give us all the knowledge of their diftiniSlions that we can acquire. Examples When a ball lies on a table, and I prefs it gently on of preffion. one fide, it moves toward the other fide of the table. • If I follow it with my finger, continuing my preifure, it accelerates continually in its motion. In like man- ner, when I prefs on ttie handle of a common kitchen jack, the fly be^'ins to move. If I continue to urge or prefs round the handle, the fly accelerates continually, and may be brought into a (late of very rapid motion. Thefe motions are the effefts of genuine prtiuire. The ball would be urged along the table in the fame man- ner, and with a motion continually accelerated, by the unbending of a fpring. Alfo, a fpring coiled up round the axis of the handle of the jack would, by uncoiling itfelf, urge round the fly with a motion accelerating in the fame way. The more I reflecl on the prelTure of my finger on the ball, and compare it with the effeft of the fpring on it, the more clearly do I fee the per- feft fimilarily ; and I call thefe influences, exertions, or aftions, by one name, pressure, taken from the moll familiar inftance of them. Again, the vei-y fame motion may be produced in the ball or fly, by pulling the ball or the machine by means of a thread, to which a weight is fufpcnded. As both are motions accelerated in the fame manner, I call the influence or aflion of the thread on the ball or ma- chine by the fame name pressure, and weight is con- fidered as a prcffing power. Indeed I feel the fame com- preffion from the real preffure of a man on my ftioul- ders that I would feel from a load laid on them. But the weight in our example is acting by the intervention of the thread. By its preffure, it is pulling at that part of the thvcud to which it is f.iftcr,ed ; this part is pul- lin"' at the next by means of the force of cohefion ; and this pulls at a third, and fo on, till the moft remote pulls at the ball or the machine. Thus m^y elafficity, weight, cohefion, and other forces, perform the ofScc of a genuine power ; and fince their refult is always a motion beginning from nothing, and accelerating by perceptible degrees to any velocity, this refemblance makes us call them by one familiar name. But farther, I fee that if the thread be cut, the weight will fall with an accelerated motion, which I will increafe to any degree, if the fall be great enough. I afcribe this alfo to a prefling power afting on the weight. Nay, ufter a very little refinement, I confider M I C S. this power as the caufe of the body's weight ) which word is but a diftinguifhing name for this particular inftance of prefling power. Gravitation is therefore added to the lift of preffures ; and, for fimilar reafons, the attraftions and repulfions of magnets or eleftric bo- dies may be added to the lift ; for they produce aftual compreffions of bodies placed between them, and they produce motions gradually accelerated, precifely as gra- vitation does, 'i'herefore all thefe powers may be dif- tinguiftied by this defcriptive name prejjurts, which, in ftriA language, belongs to one of them only. Several writers, however, f'.'.bdivide this great clafs Gravirv at. into preffions and folicitations. Gravity is a folicita- trattions, tion ab extra, by which a body is urged downward. ^"<^ r^pul- In like manner, the forces of magnetifm and electricitv, "^','"'*, J a ■ . r -I .. /T J 1.- ' conCdertd and a vaft variety ot other attractions and repuliions, ^^ prefiions are called folicitations. We fee little ufe for this dif- tinftion, and the term is too like an affeflion of mind. Impulsion is exhibited when a ball in motion puts i:,., ' i another ball into motion by hitting, or (to ipcak meta-of impul- phorically) by ftriking it. The appearances here are Hon. very different. The body that is itruck acquires, in the inftant of impulfe, a fenfible quantity of motion, and fometimes a very rapid motion. This motion is neither accelerated nor retarded after the ftroke, unlcfs it be af- fefted by fome other force. It is alfo remarked, that the rapidity of the motion depends, inter alia, on the previous velocity of the ftriking body. For inftance, if a clay ball, moving with any velocity, ftrike another equal bail which ij at reft, the ftruck ball moves with half t!ie velocity of the other. And it is farther re- nrarkible, that the ftriking body always lofes as much motion as the ftruck body gains. This univerfal and remarkable faft fcems to have given rife to a confufed or indiftlnA notion of a fort of transference of motion from one budy to another. The phraleology in gene- ral uie on this iubject expreffes this in the moft precile terms. The one ball is not faid to caufe or produce motion in the other, but to commmiieatj motion to it ; and the v/hole phenomenon is called the communication of motion. We call this an ituliflinft notion ; for furely cai^rinnim- no one will lay that he has any clear conception of it. cation of We can form the moft diltintt notion of the communi- '""t'o"-""' cation of heat, or of the caufe of heat ; of the communi-^ '^ *■*" cation or laltneis, iweetnels, and a thouiaiid other things ; but we cannot conceive how part of that iden- tical motion which was formerly in A, is now infufed into B, being given up by A. It is in our attempt to form this notion tluit we find that motion is not a thin^, not a fubftance which can exift independently, and is fufeeplible of adlua! transference. It appears in this cafe to be a llate, or condition, or mode of exiftence, of which bodies are iufceptible, which is producible, or (to fpeak without metaphorj caufable, in bodies, and which is the effect and cbaraderijlic of certain natural qualities, properties, or powers. We are anxious to have cur readers imprcfled with clear and precife notions on this fnbjeif, being confident that fuch, and only fuch, will carry them through fome intricate paths of mecha- nical and philofophical refearch. The remarkable circumftance in this phenomenon is, - . '" that a rapid motion, which requires for the effetling itforct is the the aftion of a prefling power, continued for a fenfible, diftimftive and frequently a long time, feems to be effefted in an'^haraaeroi inftant by impulfion. This has tended much to fup.""P""'°°' port the notion of the aiftual transference of fomething formerly \, D Y N A formerly polTo/Ted excliifively by the ftr!kinh!lofophi°^'^°'"'"°" *^^'"^'^- To/a//>o/c an agent tliat we do not fee, tng. " and for whofe exiftence we have not the fmalleft argu- ment ; with equal propriety we might fuppofe mini- j, ftering fpirits, or any thing that we pleafe. Orhira Other philofophers are fo diffatisfied with this notion maintain of the produftion of preffure, that they, on the other that pref. j^jn^, affirm that prefl'ure is the only moving force in fofemovinu "ature ; not according to the* popular notion of pref- forte. fure, by the mutual contaft of folid bodies, but that kind of preffure which has been cMed fo/icitation ; fuch as the power of gravity. They affirm, that there is no fuch thing as contaft on inftantaneous communication of motion by real collifion. They fay (and they prove it by very convincing fafts (fee Optics, n" 63—68. £n- cycl.), that the particles of folid bodies exert very ftrong repulfions to a fmall diftance ; and therefore, when they are brought by motion fufficiently near to another bo- dy, they repel it, and are equally repelled by it. Thus is motion produced in the other body, and their own motion is diminifhed. And they then ftiew, by a fcru- pulous confideration of the ftate of the bodies while the one is advancing and the other retiring, in what man- ner the two bodies attain a common velocity, fo that the quantity of motion before -collifion remains unchan- ged, the one body gaining as much as the other lofes. They alfo ftiew cafes of fuch mutual aftion between bodies, where it is evident that they have never come into contaft ; and yet the refult has been precifcly fimi- lar to thofe cafes where the motion appeared to be changed in an inftant. Therefore they conclude, that tliere is no fuch thing as inftantaneous comntunication, or transfufion of motion, by contaft in collifion or impulfe. The reafon why previous motion of the impelling body is ncceffary, is not that it may have a vis injila forfvi ttiolo, a force inherent in it by its being in motion, but that it may continue to follow the impelled and retiring body, and exert on it a force inherent in itfelf, whetlier in motion or at reft. — According to thefe philofophers, therefore, all moving forces are of that kind which has been named foUcitntion ; fuch as gravity. We (hall know it afterwards by the more familiar and defcriptive name of Accelerating or Retarding force. j^ The exertions of mechanical forces are differently ^Slhn, Rr. termed, according to the reference that we make to t hei'''''""'' ^'*- refult. If, in boxing or wreftling, I ftrike, or endea-" ""' vour to throw my antagonift, I am fa id to act ; but if I only parry his blows, or prevent him from throwing me, I am faid to resist. This diftinftion is applied to the exertions of mechanical powers. When one bo- dy A changes the motion of another B, we may coufi. der the change in the motion of B either as the indica- tion and ineafure of A's power of producing motion, or as the indication and mcafure of A's refiilance to the being brought to reft, or having its motion any how changed. The diftinftion is not in the thing itfelf, but only in the reference that we are difpofed, by other confiderations, to make of its effeft. They may be diftinguiftied in the following manner : If a change of motion follow when one of the powers ceafes to be ex- erted, that power is conceived as having refifted. Tlie whole langiiage on this fubjtft is metaphorical. Re- fiftance, effort, endeavour, &c. are words which cannot be employed in mechanical difcuffions without figure, becaufe they all e>:prefs notions which relate to fentient beings ; and the unguarded indulgence of this figura- tive language has fo much affefted the imagination of philofophers, that many have almoft animated all mat- ter. Perhaps the word Reaction, introduced (we think) by Newton, is the beft term for expreffing that mutual force which is perceived in all the operations of nature that we have inveftigated with fuccefs. As the magnet attrafts iron, and in fo doing is faid to all on it ; fo the iron attrafts the magnet, and may be faid to read on it. 15 With refpeft to the difficulty that has been objefted We need to the opinion of thofe who maintain that all the me- "'^'. f'PPofc chanical phenomena are produced by the agency of ^t-jiftance. trafting or repelling forces ; namely, that this fuppofcs Tendtm'y. the bodies to aft on each other at a diftance, however fmall thofe diftances may be, which is thought to be abfurd, we may obferve, that we may afcribe the mu- tual approaches or receffes to tendencies to or from each other. What we call the attra&icn of the magnet may be confidered as a tendency of the iron to the mag- net, fomewhat fimilar to the gravitation of a ftone to- ward the earth. We furely (at leaft the unlearned) can and do conceive the iron to be affefted by the mag- net, without thinking of any intermedium. The thing is not therefore inconceivable ; which is all that we know about abfurdity : and we do not knowa;iy thing about the nature or effence of matter which renders this tendency to the magnet impoffible. That we do not fee intuitively any reafon why the iron Ihould approach the magnet, inuft be granted ; but this is not enough to entitle us to fay, that fuch a thing is impoffible or in- confiftent with the nature of matter. It appears, there, fore, to be very hafty and unwarrantable, to fuppofe the impulfe of an invifible fluid, of which we know nothing, and of ths exiftence of which we have no proof. Nay , if D Y N A if it be true that bodies do not come into contaft, even when one ball hits anotlii-'r, and drives it before it, tliia invilible fluid will not folvc the ditlicuky ; bccaufc the fame ditlicullv occurs in the adion of any jiarticle of the fluid Oil the body. We are obliged to fay, that the produdlion of nuitioii without any clt/rrvcJ confab, is a much more familiar phenomenon than the produftion of motion by impidfion. More motion lias been pro- duced in this way by the gravitation of a fmall llream of water, running ever iincc the creation, than by all the impulfes in the world twice-told. A\'e do not mean by this to fay, tiiat the giving to this obferved mutual relation between iron and a loadltoue the name ten- d..'ncy m:ikes it lefs 'ibi'urd, than when we fay that the loadflonc attrafts the iron ; it only makes it more con- ceivable : It fuggeils a v.'ry familiar analogy ; but both are equally figurative cxprrflions ; at leall as the word tendency is ufed at prefent. In the language of ancient Rome, there was no metaphor when Virgil's hc.o laid, TitiJimus ill Latium. Ttnders verfus fr,hm means, in plain Latin, to approach the fun. The late way of con- ceiving the whole is to fay, that the condition of the iron depends on the vicinity of the magnet. When the e.xertions of a mechanical power are ob- ferved to be always direfted toward a body, that body is faid to attratt ; but when the other body always moves ofF from it, it is faid to repel. Thcfe alfo are metaphorical exprefiions. 1 attraft a boat when I pr.U it toward ine by a rope ; this is purely Attraction : and it is pure, unfigurative Repulsion, when 1 purti any body from me. The fame words are applied to the mechanical phenomena, merely becaufe they re- fenible the refults of real attraftion or repulfion. We mult be much on our guard to avoid metaphor in our conceptions, and never allow thofe words to fugged: to our mind any opinion about the manner In which the inechanical forces produce their efTecls. It is plain, that if the opinion of thofe who maintain the exiilence and aftion of the above-mentioned invilible fiuid be jult, tliere is nothing like attraction or repullion in the univerfe. We mull always recur to the limple pheno- menon, the motion to or from the attraction or repel- ling body ; for this is all we fee, and generally all that vi'e know. We conceive one man to have twice tlie flrength of another man, when we fee that he can witlilland the united effort of two others. Tlius animal force is con- ceived as a qujintlty, made up of, and meafured by, its own parts. But we doubt exceedingly whether this be an accurate conception. We have not a dlitindt no- tion of one drain added to another ; though we have of their being joined or combined. We want words to cxprefs the difference of thefe two notions in our own minds ; but we imagine that others perceive the fame diflerence. We conceive clearly the addition of two lines or of two minutes ; we can conceive them apart, and perceive their boundaries, common to both, where one ends and the other begins. We cannot conceive thus of two forces combined ; yet we cannot fay, that two equal forces are not double of one of them. We mealure them by the effedls which they are known to produce. Yet there are not wanting many cafes where the aftion of two men, equally ftrong, does not produce a double motion. In like manner, we conceive all mechanical forces as meafurable by thei'r efFedls ; and thus they are made SuppL. Vol. I. Part II. M 1 C S, 505 the fuhje6ts of mathenutii\il difcndion. We talk of the propoitions of gravity, magnctifm, electricity, &c. j nay, we talk of the proportion of gravity to magne- tllm : — Yet thife, confidcred in themfelves, are difpa- rate, and do not admit of any propoltion ; but tlicv produce efleC^s, fome of which arc meafuiable, and whole alTumed mealures are fufceplible of compaiiion, being quantities of the fame kind. Thus, one of the cHcCls of gravity is the acceleration of motion in a fall- ing body : magneliim will alfo aceekratc the motion ot a piece of iron ; thcfe two accelerations are compa- rable. But we cannot compare magnetifm with heat ; becaufe we do not know any meafurable efiecls of mag- netifm that are of the fame kind with any cifedts of heat. ' When we fay, that the gravitation of the moon is the By their 36coth part of the gravitation at the fea-iliorc, wetfFeils. mean that the fall of a llone in a fecond is s'ico times greater than the fall of the moon in the lame time. But we alfo mean (and this exprcdt? the proportion of the tendency of gravitation more purely), tiiat if a Hone, when hung on a fpring lleclyard, draw out the rod of the lleelyard to the mark 3600, the fame ftone, taken up to the dillilnce of tlie moon, will draw it out no further than the mark i. We alfo mean, that if the ftone at the fea-iliore draw out the rod to any mark, it will require Y'-O fuch Hones to draw it out to that mark, when the trial is made at the diltance of the moon. It is not, therefore, in confequence of any immediate perception of the proportion of the gravitation at the moon to that at the furface of the earth that we make fuch an alfertion ; but thefe motions, which we conli- der as its efletts in thefe lituations, being magnitudes of the fame kind, are fufceptible of cumparllon, and have a proportion which can be afcertaincd by obfervation. It is thcfe proportioiis that we contenTplate ; altjiough we fpeak of the proportions of the uiifeen caufes, the forces, or endeavours to defcend. It will be of mate- rial lervice to the reader to perufe the judicious and acute dilTcrtation on quantity in the 45th volume of the Philofophical TranfaCtions ; or he may Itudy the article QUANTITY in the Encychpxdia, where, we trull, he will fee clearly how force, velocity, denlity, and many other magnitudes of vciy frequent occurrence in me- chanical philolophy, may be made the fubjeCts of ma- thematical dilculiion, by means of fome of thofe projier quantities, meafurable by their own parts, wiiich are tn be alfumcd as their mealures. PrelTures are meafurable only by prelfures. When we confider them as mo- ving powers, we ftiould be able to rneafure them by any moving powers, otherwife we cannot compare theni ; therefore it is not as prelTurcs that we then meafure them. This obfervation is momentous. One circumftance muA be carefully attended to. That thofe alTumed mealures may be accurate, they mull be invariably connected with the magnitudes which they are employed to meafure, and lo coiinefted, that the degrees of the one mull change in the fame manner with the degrees of the other. This is evident, and is granted by all. But we mull alfo knaiu this of the mea- fure we employ ; we mull lee this conftant and prccife relation. How can we know this ? We do not per- ceive force as a feparate exiilence, fo as to fee its pro- portions, and to fee that thefe are the fame with the proportions of the meafurcs, in the fame manner that Euclid fees the proportions of triangles and thofe of 3 S their SC6 (cience. 19. their bafes, and that ihefe pTwportions are the fame, when 'he triangles art of equal altitudes. How do we difcover that to every magnitude which we cz\\fort:e is invariably attiched a corrcfponding magnitude of acceleration or defleftion ? — Clearly. In faft, the very exiilence of the force is an inference that we make from the obfervcd acceleration ; and the degree of the force is, in like manner, an inference from the ob- fervcd magnitude of the acceleration. Our menfiires are therefore neccfTarily connefted with the magnitudes which they meafure, and their proportions are the fame ; becaufe the one is always an inference from the other, „ both in fpecies and in degree. Dynamics ^^ '^ ""'^ evident, that thefe difquifitions are fufcep- is a dtmon-tible of mathematical accuracy. Having feleded our ftrative meafures, and obferved certain mathematical relations of thofe meafures, every inference that we can draw from the mathematical relations of the proportions of thofe reprefentations is true of the proportions of the motions; and therefore of the proportions of the forces. And thus dynamics becomes a dcmonilrative fcience, one of the difciflitut accurals. But moving forces are confidered as differing alfo in kind ; tlmt is, in dircftion. We affign to the force the direction of the obferved change of motion ; which is not oniv the indication, but alfo the charadteriftic, of the chans;ing force. We call ic an accelerating, retard- ing, deflefllng, force, according as we obferve the motion to be accelerated, retarded, or dtfle&cd. Tbefe denominations fhew us inconteftably that we have no knowledsre of the forces different from our knowledge of the effcfts. The denominations are all either defcriptive of the effefts, as when we call them accelerating, penetrating, protrufive, attraftive, or re- pulfive forces ; or they are names of reference to the fubftances in which the accelerating, protrufive, &c. forces, are fuppoied to be inherent, as when we call them ao magnetijm, ehSricity, corpiifcular, &c. Forces are When I ftruggle with another, and feel, that in order flilcovcre ^^ prevent beinj; thrown, I muil e.sert force, I learn iicGtioii to '"St ""y antagoniit is exerting torce. 1 his notion is other lot- transferred to matter; and when a moving power which "'• is known to operate, produces no motion, we conceive it to be oppofed by another equal force; the exigence, agency, and intenfity of which is detefled and mea- fured by theft means. The quiefcent ftate of the body is confidered as a change on the llate of things that would have been exhibited in coniequence of the known action of one power, had this other power not aftcd; and this change is confidered as the indication, charac- teriftic, and meafure of another power, detefted in tliis way. Thus forces are recogniied not only by the changes of mglion which they produce, but alio by the changes of motion which they prevent. The co- Lefion of matter in a ilring is inferred not only by its giving motion to a ball which I pull toward me by its intervention, but alfo by its fufpending that ball, and hindering it from falling. I know that gravity is act- ing on the ball, which, however, does not fall. The fo- iidity of a board is equally inferred from its flopping the ball which ftrlkes it, and from the motion of the ball which it drives before it. In this way we learn that the particles of tangible matter cohere by means of moving forces, and that they refill compreffion with force ; and in making this inference, we find that this «orpufcular force exerted between the particles is ^lu- DYNAMICS. tual, oppofite, and equal : for we muft apply force F'"(^ I.iw equally to a or to b, in order to produce a feparation ° Motion. or a compreffion. We learn their equality, by ohfer- ' | ring that no motion enfues while thefe mutual forces are known to aiSt on the particles ; that is, each is op- pofed by another forte, which is neither inferior nor lu- perior to it. Of the Laws of Motion. Such, then, being our notions of mechanical forces, the cauies of the fenfible changes of motion, there will refult certain confequcnces from them, which may be called axioms or laws of motion. Some of thefe may be intuitive, offering themfelves to the mind as loon as the notions which they involve are prefented to it. Others may be as necclFary refults from the relations of thefe notions, but may not readily offer themfelves without the mediation of axioms of the firft clafs. We fhall fc'ieft thofe which are intuitive, and may be taken for the firft principles of all difcuflions in mechanical phllofophy. First Law of Motion. Every body continues in a Jlate of rejl, or of uniform rec- tilineal motion, unlefs offeBed by fome mechanical force. This is a propofition, on the truth of which the whole fcience of mechanical philofophy ultimately depends. It is therefore to be ellabliflied on the firmell foundation ; and a folicitude on this head is the more jullifiable, becaufe the opinions of philolophers have been, and ilill are, extremely different, both with refpett to the truth of this law, and with refpeft to the foundation on which it is built. Thefe opinions are, in general, very obfcure and unfatisfa&ory ; and, as is natural, they in- fluence the difcuffions of thofe by whom they are held through the whole fcience. Although of contradic- tory opinions one only can be juft, and it may appear iufficient that this one be eftabliflied and uniformly ap- plied ; yet a fhort expofition, at leall, of the red is ne.- ctffary, that the greatell part of the writings of the phi- lofophers may be intelligible, and that we may avail our- felves of much valuable information contained in them, by being able to perceive the truth in the midft of their imperfect or erroneous conceptions of it. It is not only the popular opinion that reft is the natural (late of body, and that motion is fomething fo- reign to it, but it has been ferioufly maintained by the greateil part of thofe who are elleemed philofophers. They readily grant that matter will continue at reft, unlefs fome moving force att upon it. Nothing feems neceffary for matter's remaining where it is, but its continuing to exift. But it is far otherwife, fay they, with refpeCt to matter in motion, plere the body is continually changing its relations to other things; there- fore the continual agency of a changing caufe is necef- fary (by the fundamental principle of all philofophical difculhon), for there is here the continual production of an effect. They fay that this metaphyfical argu- ment receives complete confirmation (if confirmation of an intuitive truth be neceffary) from die moft fami- liar obfervation. We fee that all motions, however violent, terminate in reft, and that the continual exer- tion of fome force is neceffary for their continuance. Tliefe philofophers therefore affert, that the conti- nual action of the moving caufe is cjenlialty neceffary for 21.. Does COD-- tinued mo» tion indi- cate contia nued Ac- tion 2-? Whimficsl- t otion of elemental minds , Flrft Law if Motion. »4 ^(ftinn not icceflary or the iontjnu- :nce of notiun. for till eoiitlmifliice of the motion : but they differ among tliemfelvcs in their notions and opinions about this canfe. Some maintain, that all the motions in the univerfe are produced and continued by tlie immediate an-cncy of Deity ; otiiers affirm, that in every particle of matter there h inherent a fort of mind, the f""^'? and 'ujTipvJ-u/^n of Aritlole, which they call an Ele- mental Mind, which is the caufe of al! its motions and changes. An overweaning reverence for Greek learning has iiad a great iiiflucnce in reviving this doc- trine of Arillotle. The Greek and Roman languages are affirmed to be more accurate expreffions of human thought than the modern languages are. In thofe an. cient languages, tht verbs which exprefs motion are employed both in the aftive and paffive voice ; whereas we have only the active verb to move, for expreffing both tiie ftate of motion and the adl of putting in mo- tion. " The itone moves down the fiope, and moves all the pebbles which lie in its way ;" but in the an- cient languages the mere ftate of motion is always ex- preffed by the paffive or middle voice. The accurate conception of the i'peakers is therefore extolled. The Hate of motion is exprefied as it ought to be, as the refult of a continual aCtion." Kn'silai, movetur, is equi- valent to " it is moved." According to thefe philo fophers, every thing which moves is mind, and every thing that is moved is body. The argument is futile, and it is falfe; for the modern languages are, in general, equally accurate in this in- ilance : " fe mouvoir," in French; '^ Jtch leauegen," in Germnn ; " dvigatfu," in Sclavonic ; are all paffive or refletted. And the ancients faid, that " rarin falls, wa- ter runs, fmoke rifes," juft as we do. i'he ingenious author of Ancient Aletaphyjtcs has taken much pains to gives us, at length, the procedures of thole elementary minds in producing the oftenfible phenomena of local motion ; but it feems to be merely aji abufe of lan- guage, and a very frivolous abufe. This elemental mind is known and charafterifed only by the effeft which we afcribe to its attion ; that is, by the motions or changes of motions. Uniform and unexcepted ex- perience fhews us that thefe are regulated by laws as precife as thofe of mathematical truth. We confider nothing as more fixed and determined than the com- mon laws of mechanifra. There is nothing here that indicates any thing like fpontaneity, intention, pur- pofe ; none of thole marks by which mind was firft brought into view : but they are very like the effeils which we produce by the exertions of our corporeal forces ; and we have accordingly given the name force to the caufes of motion. It is furely much more ap- pofite than the name mind, and conveys with much more readinefs and perfpicuity the very notions that we wifli to convty. We now wifh to know what reafon we have to think that the continual action of fome caufe Is neceffary for continuing matter in motion, or for thinking that reft is its natural tfate. If we pretend to draw any argu- ment from the nature of matter, that matter muft be known, as far as is neceffary for being the foundation of argument. Its very exiftence is known onlv from oljfervation ; all our knowledge of it muft therefore be derived from the lame fource. If we take this way to come at the origin of this opinion, we lliall find that experience gives us no au- thority for faying that reft is the natural condition of DYNAMICS. 507 matter. We cannot fay that we !nv« ever feen a body Fi'd i-f M. ti(n,[,^.p„ ^j,1j, ,„ j,j^.g it_ jt would appear to fct out with ^""^ tliis unmeafurablc velocity to the eaftward ; to be gra- dually retarded by tlie refiftance of the air, nid at lail l.rought to reft by hittinir the ground. But, by reafon of the earth's motion roiuid the fun, the fail is quite the revcrfe. Immediately before the difcliarge, the ball was moving to the well ward with the velocity of 90,000 feet per fecond nearly. By the explofion of the pow- der, and its preflure on the ball, fume of this motion is dellroved, and at the muzzle of the gun, the ball is raovincj {lower, and the cannon Is hurried away from it to the weftward. The air, which is alfo moving to the . weftward f)O,0CO feet in a Iccond, gradually communi- cates motion to the ball, ii> the fame nwnncr as a hur- ricane vi'ould do. At lall (the ball dropping all the while) fome part of the ground hits tlie ball, and car- ries it along with it. Other obfcrvations mud therefore be reforted to, in order to obtain an experimental proof of this propofi- tion. And fuch are to be found. Although we cannot nieafure the abfolute motions of bodies, we can obferve and mcafure accurately their relative motions, which are the differences of their abfolute motions. Now, if we can (hew experimentally, that bodies fliew equal ten- dencies to refift the augmentation and the diminution of their relative motions, they, i/fo faSo, fliew equal ten- dencies to refiilthe augmentation or diminution of their abfolute motions. Therefore let two bodies, A and B, be put into fuch a fituation, that they cannot (by rea- fon of their impenetrability, or the aftions of their mu- tual powers) perfevere in their relative motions. The change produced on A Is the efFcft and the mcafure of B's tendency to perfevere in its former Rate ; and there- fore the proportion of thefe changes will Ihew the pro- portion of their tendencies to maintain their former ftatcs. Therefore let the following experiment be made at noon. E»peri- Let A, apparently moving weftward three feet per mems po- fecond, hit the equal body B apparently at reft. Sup- per for the pofe^ ly/^ That A impels B forward, without any di- " ° ^' minution of its own velocity. This refult would ftievv that B manifcfts no tendenc)' to maintain its motion un- changed, but that A retains its motion undiminifhed. ja'/v, Suppofe that A ftops, and that B remains at reft. This would ftiew that A does not refift a diminu- tion of motion, but that B retains its motion unaug- mented. 31/1}', Suppofe that both move weftward with the ve- locity of one foot per fecond. The change on A is a diminution of velocity, amounting to two feet per fe- cond. Tliis is the effccl and the irieafure of B'.^ ten. dency to maintain its velocity unaogmented. The change on B is an augmentation of one foot per fecond made on its velocity ; and this is the meafure of A's tenden- cy to maintain its velocity uiidiminiflied. This tenden- cy is but half of the former ; and this refult would ftiew, that the refiilance to a diminution of velocity is but half of the refiftance to augmentation. It is per- haps but one quarter ; for the change on B has produ- ced a double change on A. 4w This is the ifRft and the mcafure of A's whole ten-"'' Motion. dency to retain its motion undiminifhed. Half of this ' change on B meafurcs the perfevcriiig tendency of the halt of A; but A, which formerly moved with the ap- parent or relative velocity three, now moves (by the fuppolition) with the velocity two, having loft a velo- city of one foot per fecond. Each half of A therefore has loft this velocity, and the whole lofs of motion is two. Now this is the meafure of B's tendency to maintain its former ftate unaugmentcd; and this is the fame with the meafure of A's tendency to maintain its own former ftate undiminidied. The concUifion from fuch a refult would therefore be, that bcdies have equal tendencies to maintain their former ftates of motion without augmentation and without diminution. AV'hat is fuppoied in the 4//} and j//j cafes is really the rcfidt ol all the experiments which have been tried ; and fhis law regulates all the changes of motion which are produced by the mutital aAIons of bodies in impul- iions. This afltrtlon is true without exception or qua- lification. Therefore it appears that bodies have no preferable tendency to reft, and that no fait can be ad- duced which lliould make us fuppofe that a motion once begun fhould fi:lfer :;ny diminution without the aftion of a changing caufe. But we muft now obferve, that this way of eftablilh-Entcxpe- ing the firft law of motion is very imperfect, and alto-f'^ncr is gether unfit for rendering it the fundamental principle """/^"^P^"* of a whole and extenfive feience. It is fubjeft to allf^o^ „f";f' the inaccuracy that is to be found in our beft experi- axiom. ments ; and it cannot be a])plled to cafes where fcru- pulous accuracy is wanted, and wiicre no experiment: can be made. Let us therefore examine the propofition by means of the general principles adojited in the article Philo- sophy, F.ncycl. wliich contain the foundation of all our knowledge of aftive nature. Thefe principles will, we Imagine, give a decifion of this quellion th;it Is fpee- dy and accurate, fhewing the propofition to be an axi- om or intuitive confequence of the relations of thofe ideas which we have of motion, and of the caufes of its produftlon and changes. It has been fully denionftratcd that the powers or Logics! forces, of which we fpeak fo much, arc never the imme-P™"^' diate objects of our perception. Their very exiftence, their kind, and their degree, are Inftlntlive inferences froiTi the motions which we obferve and dafs. It evi- dently follows from this experimental and univerfal truth, yl. That where no change of motion is obfer- ved, no fuch inference Is made ; that is, no power is Juppnji-d to act. But whenever any change of motion is oblerved, the Inference Is made ; that is, a power or force is fuppofed to have afted. In the fame form of logical conclufion, we muft fay that, 2dly, When no change of motion \i j'uppofid or thought of, no force h fuppofed ; and that whenever we fuppofe a change of motion, we, In fact, though not in terms, fuppofe a changing force. And, on the other hand, whenever we fuppofe the adion of a changing force, we fuppofe the change of motion ; for the adbon of this force, and the change of motion, is one and the fame thing. We cannot think of the adtion without thinking of the indication of that aftion ; that is, the change of motion. — In the fame manner, when we do not thlok of a changing force, or fuppofe tbat there is no eio DYNAMICS. Kirft Law f(o niSlion of a cliangiiig force, we, in faft, though not "''""• in terms, fiipporo that there is no iiidicttion of this It is a lr.-.v of luin^:tn tlKUgtit, •'PI' clianging force ; that is, that there is no change. Whenever, therefore, we luppofe that no mtclianical force is aifting on a body, we, in fadl, fuppofr that the body continues in its former condition with refpcft to motion. It wc fnp])o(e that nothing accelerates, or re- tards, or dcliedls tlie motion, wc fuppofe that it is not accelerated, nor retarded, nor deflected. Hence fol- lows tlie pi opofition in exprefs terms ~ ITe fti/>f>oJi that tie loily cor.linues in Us former Jiute of reft or motion, un- hfs ive fuppofe that it is changed by fame meckamcal force. Thiis it appears, that this propofition is not a matter of expeiience or contingency, depending on the proper- tics which it lias pleafed the Author of Nature to be- llow on body : it is, to us, a neceffary truth. The propofition dots not fo much exprefs any thing with re- gard to body, as it does the operations of our mind when contemplating body. It may perhaps be effential to body to move in fome particular direftion. It may be eflcntial to body to ftop as foon as the moving caule lias ceafed to aft ; or it may be effential to body to di- niinifh its mction gradually, and finally come to rell. But this will not invalidate the truth of this propofi- tion. Thefe circumftances in the nature of body, which render thofe luodifications of motion effentially neceffary, are the caufes of thofc modifications ; and, in our ftudy of nature, they will be confideied by us as changing forces, and will be known and called by that name. And if we fhould ever fee a particle of matter in filch a fituation that it is affefted by thofe effential properties alone, we fhall, from obfervation of its mo- tion, difcover what thofe effential properties are. And almoft This law turns out at laft to be little more than a an identical {gyfQijjgjj-gl propofition: But mechanical philofophy, "' ' "'as we have defined it, requires no other fenfe of it : for, even if we (hould fuppofe that body, of its own nature, is capable of changing its ftate, this change mufl be performed accordi»g to fome law which charac- teriles the nature of body ; and the knowledge of the law can be had in no other way than by obferving the deviations from uniform reftilineal motion. It is there- fore indifferent whetlier thofe changes are derived from the nature of the thing, or from external caufes : for in order to confider the various motions of bodies, we inufl firfl confider this nature of matter as a mechanical affeftion of matter, operatmg in every inflance ; and thus we are brought back to the law enounced in this propofition. This becomes more certain when we re- fieft that the external caufes (fuch as gravity or mag- rjCtifm), which are acknowledged to operate changes of motion, are equally unknown to us with this eflential original properly of matter, and are, like it, nothing but inferences from the phenojnena. The above very diffufe difeuffions may appear fuper- fiuous to many readers, and even cumberfome ; but we trull that the philofophical reader will excufe our anxie- ty on this head, when he. reflefts on the complicated, indiflinft, and inaccurate notions commonly had of the fubjeft ; and more efpecially when he obferves, that of thofe who maintain the truth of this fundamental pro- pofition, as we have enounced it, many (and they too of the firfl eminence), rejeft it in faft, by combining it with other opinions which are inconfiflent with it, nay, -^vhich contradict it; in exprefs terms. We may even include Sir Ifaac Newton in the fiumbcr of thofe who Firft Lfw have at leafl intKuiuced modes of exprcifion which mif.of ^"''o"- lead the minds of incautious perions, and fuggefl iiiade- * quale notions, incompatible with the pure do(^trine of the propofition. Although, in words, they d if claim the dodtrine that rell is the natural ftate of body, and that force is uccefl'ary for the continuation of its motion, yet in words they (and moll of them in thought) like- wife abet that dodrine : for they fay, that there nfides in a moving body a power or force, by which it perfe- veres in its motion. They call it the vis in sir A, the INHERENT FORCE OF A MOVING BODY. This is furelv giving up the quellion : for if the motion is fuppofej to be continued in confequence of a force, that force is fuppofed to be exerted ; and it is fuppofcd, that if it were not exerted, the motion would ceafc ; and there- fore the propofition mull be falfe. Indeed it is forae- timcs exprelfed fo as feemingly to ward off this objec- tion. It is faid that the body continues in uniform rec- tilineal motion, unlefs afl'efted by fome external caufe. But this way of fpeaking obliges us, at firfl felting out in natural philofophy, to aflert that gravity, magnetifm, eleftricity, and a thoufand other mechanical powers, arc external to the matter which they put in motion. This is quite improper : it is the bufinefs of philofc phy to difcover whether they be external or not ; and if we affert that they are, we have no principles of ar- gumentation with thofe who deny it. It is this one thing that has filled the ftudy of nature with all the jargon of sthers and other invifible intangible fluids, which has difgraced philofophy, and greatly retarded ils progrefs, 32 We mull oblerve, that the terms vis infita, \aherenX. Fi, hfiia, forte, are very improper. There is no difpute among ''''>"='^'"' philofophers in calling every thinp a force that pro-- '"'^'^° J t_ r • 1 ■ ■ r ■ 1 X- improper duces a change or motion, and in interring the action terms in of fuch a force whenever we obferve a change of mo- th-ir ufual tion. It is furely incongruous to give the fame name ''."^^P"" to what has not this quality of producing a change, or"""' to infer (or rather to fuppofe) the energy of a force when no change of motion is obferved. This is one among many inllances of the danger of millake when we indulge in analogical difcuflions. All our language, at leafl, on this fubjeft is analogous. I feel, that in order to oppofe animal force, I mufl exert force. But I mull exert force in order to oppofe a body in motion : Therefore I imagine that the moving body poffeffes force. A bent fpring will drive a body forward by un- bending : Therefore I fay that the fpring exerts force. A moving body impels the body which it hits ; There- fore I fay, that the imptlling body poflTefles and exerts force. I imagine farther, that it polfeffes force only by being in motion, or becaufe it is in motion ; becaufe I do not find that a quielccnt body will put another into motion by touching it. But we fliall fuon fin into mechanical philufophy ; and it is now in conftantin«K«. ufe. But writers are very carelefs and vague in the no. tlons which tiiey affix to thefe terms. Kepler and New- ton fcem generally to employ it for exprelfirg the fad, the perfeverance of the body in its prefent ftate of mo- tion or reft: but they alio frequently exprefs by it fomething like an indifference to motion or reft, man'i- fejled Ly its requiring the fame quantity of force to make an augmentation of its motion as to make an equal diminu- tion oj it. The popular notion is like that which wc have of aftual reliftance ; and it always implies the no- tion of force exerted by the refifting body. Wc fup- pofe this to be the exertion of the vis iiijita, or the irJie- rent force of a body in motion. But we have the fame notion of refillance from a body at reft which we fet in motion. Now furely it is in direft contradidion to the common ule of the word force, when we fuppofe re- liftance from a body at reft ; yet vis inertia: is a vtxy common exprelTion. Nor is it more abfurd (and it 14 vei7 abfurd) to fay, that a body maintains its ftate of reft by the exertion of a -vis inertia, than to fay, that it maintains its ftate of motion by the exertion of an inherent force. Wt ftiould avoid all fuch metapho- rical expreflions as refiflance, indifference, fluggifincfs, or pronenefs to reft (which fome exprefs by inertia)i b.-- caufc they feldom fail to make us indulge in metaplii. rical notions, and thus lead us to mifconceive the modus operandi, or procedure of nature. There is no rcjljlance whatever ohferved in thefe phe- nomena ; for the force employed always produces it*. complete effed. When I throw down a man, ami find that I have employed no more force than was fufficient to throw down a fimilar and equal mafs of dead matter, I know by this th it he has not refilled ; but I con- clude that -he has refifted, if I have been obliged to em- ploy much mure force. There is therefore no refill- ance, properly fo c;dled, when the exerted force is oh- ferved to produce its full elfed. To fay that there ;> refiftance, is therefore a real mifconception of the way in which meciianical forces have operated in tlie colli, lion of bodies. There is no more reiiftance in thefe cafes than in any other natural changes of condition. We are guilty, however, of the fame impropriety of language in other cafes, where the caufe of it is more evident. We fay that colours in grain njifl the adion of foap and of the fun, but that PrulTnn bine does not. We all perceive, that in this exprediun tlie v/oid re- fiftance is entirely figurative : and we fliould f;iy that Pruflian blue refjls foap, if we are right in faying tli.it a body refifts any force employed to change its fhte of motion ; for foap mufl be employed to difciiarg-e or change the culour ; and // dues change it. Force mufl; be employed to change a motion ; and it does change it. The impropriety, both of thought and langiuige, 'n plain in the oi;c care, ar.d it is no kfs real in ihc other. Both. 512 DYNAMICS. loi'ce. Seco'i'iLaw of the terms, inherent farc» aiul imrtia, may be ufed changes, and that thefe proportione arc the fame j and SecnndLn: of Motion. ^j^jj fafety for abbreviating language, if wc be careful from having obferved that this has obtained through °/ M utimi ^" * ' ' ' to employ them only for exprefiing, either the Jimpk fa& the whole extent of our lludy of nature. This would * " of perfevcrin" in the former Jlats, or the necejjity of em- indeed eftabhlli ic as a phylxal law, an univerlal taft ; ployin" a certain deiirminette force, in order to change that and it is, in faft, fo eilablilhcd. But this does not efta- 36 fiate, and if we avoid all thought of refjlance. blilh it as a law of motion, according to our definition Deviations I'lom the whole of this difcuflion, we learn, that the of that term ; as a law of human thought, the rcfult of from uni- J^vjations from uniform motions are the indications of the relations of our ideas, as an intuitive truth. Tlie Itieal'^mn-' the txiltence and agency of mechanical forces, and that injudicious attempts df philolophers to prove it as a tion arc the they are the only indications. The indication is very matter of obfervatlon, have otcalinned the only difpute only indica-jjfiiple, mere change of place ; it can therefore indicate that has arileii ia mechanical philofophy. It is well nothing but what is very iimple, the fomething com- known that a bullet, moving vith double velocity, pe- petent to the produftion of the very motion that we netrates four times as far. Many other fimilar latls ohferve. And when two changes of motitm are pre- corroborate this: and the philofophers obferve, that clfely fimilar, they indicate the fame thing. Suppofe a four times the foree has been expended to generate this mariner's compafs on the table, and that by a fmall tap double velocity in the bullet ; it requires four times as with my finger I caufe the needle to turn off from its qui- much powder. Tn all the examples of this kind, it would efcent pofition 10 degrees. I can do the fame thing by feem that the ratio of the forces employed has been bringing a magnet near it; or by bringing an eletlrified very accurately afcertained ; yet this is the invariable body near it ; or by the unbending of a fine fpring reftilt. Philofophers, therefore, have concluded, that j)reii othi fame ; therefore the thing indicated is the fame, nume- is a ilrong confirnKition, to fee that the bodies in mO ly, a certain intenfity and direftion of a moving power, tion feem to poflels forces in this very proportion, and How it operates, or in what manner it exifts and exerts produce eftefts in this proportion ; penetrating four itfelf in thefe inllances, outwardly fo difterent, is not times as deep when the velocity is only twice as great, under confideration at prcfent. Impulfivenefs, intenfity, &c. and dlretlion, are all the circumllances of refemblance Qy near 11 . 01 uy uut uuui-nwiug v/i « *»in. i^i.i<>^ i^-iuil. i miui'JlJii'.is, i.ii»-i*_ikyn., naw ^-uuv-iiiuv-vi, i.iit*i- Siliag it alide ; or by a puff of wind; or by ieveral moving forces are not proportional to the velocilieswhlch [ler tnethods. In all thefe cafes, the indication is the they produce, but to the fquares of thofe velocities. It by which the afleflions of matter are to be charafterifed ; and it is to the difcovery and deternu'nation of thefe alone that our attention is nOw to be diredled directed in this refcarch by the Second Law of Motion. But if this be a juft eftimation, we cannot reconcile it to the conceffioii of the fame philofophers, who grant that the velocity is proportional to the force imjjvefled. We are in the cafes where we have no previous obfervation of the ratio of the forces, and of its equality to the ratio of the velocities. This is the cafe with gravity, which thefe philofophers always meafnre by its accelerating Every change of motion is proportional to the force imprejfcd, power, or of the velocity which it generates in a given and is made in the direction of that force. time. And this cannot Ijc ref\ifed by them ; for cafes This law alfo may almoft be confidcred as an identl- occur, wlierc the force can be meafured, in the molt na- cal propofition ; for it is equivalent to faying, that the tural manner, by the adual preffure which it exerts, changing force is to be meafured by the change which Gravity is thus meafured by the preifiire which a Hone it produces, and that the diredllon of this force is the exert,5 on its fupporls. A weight which at Quito will diredxion of the change. Of this there can be no doubt, pull out the rod of a fpring lleciyard to the mark 312, when we confider the force in no other fenfe than that will pull it to 313 at Spitzl)ergen. And it is a faft, of the caufe of motion, paying no attention to the form that a body will fall 313 inches at Spitzbergen in the or manner of its exertion. Thus, when a pellet of tow fame time that it falls 3 1 2 at Qjjito. Gravitation is is (hot from a pop-gun by the expanfion of the air com- the caufe both of the preffure and the fall ; and it is a preffed by the rammer, or where it is fliot from a toy matter of imexcepted obfervation, that they Irave al- piftol by the unbending of the coiled wire, or vilieii it ways the fame ratio. The philofophers who have fo is nicked away by the thumb like a marble — if, in all llrenuoully maintained the other meafure of forces, are thele cafes. It moves ofi^ in the fame direftion, and with among the moft eminent of thofe who have examined the fame velocity, we cannot confider or think of the the motions produced by gravity, magnctilm, eleftricity, force, or at leall of its exertion, as any how different. &c.; and they never think of meafuring tl:ofe forces Nay, when It is driven forward by the inftantaneous any other way than by the velocity. It is In tills way percuifion of a fmart (Iroke, altliougli the manner of that the whole of the ccleftlal phenomena are explained producing this effecl (If pofiiblc) is eltenllally dliferent in perfeft uniformity with obfervation, and that tlie from what is conceived in tlie other cafes, we mull llill Newtonian philofophy is confidered as a demonltrative think that the propelling force, confidered as a pro- fclence. pelliiig force, is one and the fame. In (liort, this law There muil, therefore, be fome defeft in the principle of motion, as thus expreffed by Sir Ifaac Newton, is on which the oiher mealurement of forces is built, or equivalent to faying, " That we take the changes of in the method of applying it. Prefi'ure is undoubtedly motion as the meafures of the changing forces, and the the immediate and natural mcaiure of force ; yet we direftion of the change for the indication of the direc- know that four fprings, or a bow four times as ftrong, tion of the forces :" For no rcfiefting perfon can pre- give only a double velocity to an arrow, tend to fay, that it is a dcduftion from the acknowledged The truth of our law refts on this only, that we affume principle, that effeds are proportional to their caufes. the changes of motion as the meafure of the changing We do not affirm this law, from having obferved the forces ; or, at leaft, as the meafures of their exertions in proportion of the forces and the proportion of the producing motion. In fad, they are the meafures only of 38 Ch»iij;e of mntiun is, tfclf, a mo .ion* 5cfrn 1I.1W of a certain circumftance, in whicli the a£lions of very rf M 'tion Jlffereiil natural powers may refemble each other ; name- • Iv, the competency to produce motion. Tlicy do not, perhaps, mcalure their competency to produce heat, or even to hend fprings. We can furely confider this a- part from all other circumllanccs ; and it is worthy of feparate confidcration. Let iis fee what can be, an^ what onglit to be, deduced from this way of treating the fubjedl. The motion of a body may certainly remain unchan- ged. If the direftion and velocity remain the (anie, we "perceive no circumftance in which its condition, with refpeft to motion, differs. Its change of place or (itu- ation can make no difference ; for this is implied in the very circumftance of the body's being in motion. But if either the velocity or direAion change, then furely is its mechanical condition no longer the fame ; a force has afted on it, either intrinfic or from without, eithpr accelerating, or retarding, or deflecting it. Sup- pofing the direftion to remain the fame, its difference of condition can conlift in nothing but its difference of velocity. This is the only circumftance in which its Condition can differ, as it paffes through two different points of its reftilineal path. It is this determination by which the body will defcribe a certain determinate fpace uniformly in a given time, which defines its con- dition as a moving body : the changes of this determi- nation are the meafures of their own caufts ; — and to thofe caufes we have given the name force. Thofe caufes may refide in other bodies, which may have other properties, charadlerifed and meafured by other effc"'l change of motion, and mark it by charafters that are""^'' confpicuous and dlftinguifliing ; and this mark and mea- fure of change muft be a motion : Then we mnft fay, that the changing force is that which would produce this motion in a body previonfly at reft. We muft fee how this is manifcft, as a motion, in the difference be- tween the former motion and the new motion ; and, on the other hand, we mnft fee how_ the motion |)roduce- able in a quiefccnt body may be fo combined with a motion already exifting, as to exhibit a new motion, in which the agency of the changing force may appear. Suppofe a (hip at anchor in a llrcam; while one man walks forward on the quarter-deck at the rate of two miles per hour, another walks from ftem to ftcrn at tiie fame rate, a third walks athwart ftiip, and a fourth ftands ftiU. Let the ftiip be fuppofed to cut or part her cable, and float down the ftream at the rate of three miles per hour. We cannot conceive any difference in the change made on each man's motion in abfoliite fpace ; but their motions are now exceedingly different from what they were : the firft man, whom we may fuppofe to have been walking weftward, is now moving eaftward one mile per hour; the fecond is moving eaft- ward four miles per hour ; and the third is moving in an oblique direction, about three points north or fouth of due e.ift. All have fuffcred the lame change of con- dition with the man who had been ftandmg ftiil. He has now got a motion eaftward three miles per hour. In this inftance, we fee very well the circumftance of famenefs that obtains in the change of thele four con- ditions. It is the motion of the Ibip, which is blended with the other motions. But this circumftance is e- qually prefent whenever the fame previous motions arc changed into the fame new motions. We n:jft learn to explfcate this ; which we fliall do, by cor.fidering the manner in which the motion of the fiiip is blended with each of the mens motions. .j This kind of conihination has been called the CoMPO-Comp.>fi. siTiON OF MOTION ; becaufe, in every point of the mo-""" of mo- tion really purfucd, the two motions are to be found. '""* The fnridaniental theorem on this lubjeft is this; — Two uniform motions in the fides of a parallelogram compoie an uniform motion in the diagonal. Suppofe that a point A (fig. l.) defcribes AB uni- Plate XXI. . formly in fome given time, while the line AB is car- ried uniformly along AC in the fame time, keeping al- ways parallel to its firll poiition ;^B. The point A, by the combination of thele motions, will deicribe AD, the diagonal of the parallelogram ABDC, uniformly in the fame time. For it is plain, that the velocities in AB and AC are proportional to AB and AC, becauie they are uni- formly dcfcribed in the fame time. When the point has got to E, the middle of AB, the line AB has got into the fituation GH, half way between AB and CD, % T and 5J4 Second!. aw of Mr.tiiin. DYNAMICS. 43 Its mark and mea- lure. 44 Changing force. It» effefl. and the point E Is in the place e, the niiJdle of GH. Draw Ef L parallel to AC. It is plain that the pa- rallelograms ABDC and AE e G are fimilar ; becaufe AE and AG are the halves of AB and AC, and the angle at A is common to both. Therefore, by a pro- pofition in the El'-mciits, they are about the fdnie dia- gonal, and the point e :s in the diagonal of AD. In like manner, it may be fliewn, that when A has de- fcribed AF, Jths of AB, the line AB will be in the fituation IK, fo that AI is Jths of AC, and the point /', in which A is now found, is in the diagonal AD. It will be the fame in whatever point of AB the de- fcribing point A be fuppofid to he found. The line AB will be on a fimilar point of A.C, and the defcri- bing point will be in the diagonal AD. Moreover, the motion in AD is uniform : for A <■ is defcribed in the time of defcribing AE ; ,that is, in half the time of defcribing AB, or in half the time of defcribing AD. In like manner, A/ is defcribed in |ths of the time of defcribing AD, Sic. &c. Laftly, the velocity in the diagonal AD is to the velocity in either of the fides as AD is to that fide. This is evident, becaufe they are uniformly defcribed in the fame time. This is juftly called a compnfu'wn of the moticns .'\B and AC, as will appear by confidering it in the follow. ing manner : Let the lines AB, AC be conceived as tvpo material lines like wires. Let AB move uniformly from the fitnation AB into the fituation CD, while AC moves uniformly into the fituation BD. It is plain that their interfeftion will always be found on AD. The point e, for example, is a point common to both lines. Confidered as a point of EL, it is then mo- ving in the direftion f H or AB ; and, confidered as a point of GH, it is moving in the direftion e L. Both of thefe motions are therefore blended in the mo- tion of the interfeftion along AD. We can conceive a fmall ring at e, embracing loofely both of the wires. This material ring will move in the diagonal, and 'will really partake of both motions. Thus we fee how the motion of the (hip is aftually blended with the motions of the three men ; and the circumftance of famenefs which is to be found in the four changes of motion is this motion of the (hip, or of the man who was (landing ftill. By compofition ■with each of the three former motions, it produces each ©f the three new motions. Now, when each of two primitive motions is the fame, and each of the new mo- tions is the fame, the change is furely the fame. If one of the changes has been brought about by the ac- tual compofition of motions, we know precifely wlr.it that change is ; and this informs us what the other is, in whatever way it was produced. Hence we infer, that, When a motion is any how changed, the change is that motion which, iL'hm compounded with the former motion, will produce the new motion. Now, becaufe we alTunie the change as the meafure and charatteriftic of the changing force, we muft do fo in the prefent inftance j and we muil fay, That the changing force is that which will produce in a quiefcent body the motion which, by compofition with the former motion of a body, will produce the new motion. And, on the other hand, When the motion of a body is changed by the adion of any force, the new mclioi* is that which is compounded of the former motion, and of the motion which the force waM/rfSero»i![.aw' produce in a quiefcent body. . liMoMon. When a force changes the direftion of a motion, we p^n.fj: fee that its direftion is tianfverfe in fome angle BAC •,/„,.!. becaufe a diagonal AD always fuppofcs two lides. A» we have didinguidied any change of direftion by the term DtFLtcTioN, we may call the tranfverfe (oice a DEFLtCTING FORCE. In this way of ellimating a change of motion, all the charafters of both motions are preferved, and it ex- preffes every circumftance of the change; the mcie change of direftion, or the angle BAD, is not enough, becaufe the fame force will make different angles ot defleftion, according to the velocity of the former mo- tion, or according to its direftion : but in this ellima- tion, the full effeft of the deflefting force is feen ; it is feen as a motion ; for when half of the time is elapfcd,. the body is at e iuftead of E ; when three- fourths are elapfed, it is atyinftead of F ; and at the end of the time it is at D inllead of B. In (liort, the body has mo- ved unifcinily away from the points at which it would, have arrived independent of the change ; and this mo- lion has been in the fame direftion, and at the fame rate, as if it had moved from A to C by the changing force alone. Each force has produced its full efftit ; for when the body is at D, it is as far from AC as it the force AC had not afted on it ; and it is as far from AB as it would have been by the aftion of AC alone. For all thefe reafons, therefore, it is evident, that if we are to abide by our meafure and charafter of force as a mere producer of motion, we have felefted the proper charafteriftic and meafure of a changing force : and our defcriptions, in conformity to this fel;ftion, mull: be agreeable to the phenomena of nature, and re- tain the accuracy of geometrical procedure ; becaufe, on the other liand, the refults which we deduce from the fuppofed inlluence of thofe forces are formed in the fame mould. It is not even requilite that the real exertions of the natural forces, fuch as prefTure of va- rious kinds, 5:c. (hall follow thefe rules ; for their de- viations will be confidered as new forces, although they are only indications of the differences of the real forces from our hypothefis. We have obtained the precious advantage of mathematical inveftigation, by which vi can examine the law of exertion which charafteriles every force in nature. On thefe principles we eftablifii the following funda- mental elementary propofition, of continual and indil? penfable ufe in all mechanical inquiries, ^5 If a body or material particle be fuljeSled at the fame /;mf Fumlamen- to the aHion of two moving forces, each of which would^^^^^°"^ fcparately cavfe it to dtfcnbe the fide of a paraUelogram iinforrnly in a given time, the body will dijcrde the dia- gonal uniformh in the fame time. For the body, whofe motion AB was changed into AD, had gotten its motion by the aftion of fome forte. It was moving along NAB; and, when it reach- ed the point A, the force AC afted on it. The pri- mitive motion is the fame, or the body is in the fame condition in every inftant of the primitive motion. It. may have acquired this motion when it was in N, or when at O, or any other point of NA. In all thefe cafes, if AC aft on it when it is in A, it will always defcribe AD ; therefore it will defcribe AD when it acquires the primitive motion alfo in A ; that is, if the two for- ces DYNAMICS. Compojitlon tfjareest 4«. Refolution f>f fortes. 3;cnrc!I,a'rce8 ai£l on it at one and tin fame iiil\ant. Tlie dtmon- ot M- 1 1011 jtiation may bt neatly expicflld thus : The change in- ' iluced by cacli force on the motion produced by the other, is the motion which it would produjc in the bo- dy if previoufly at veil. Therefore the motion refult- ing from joint action is the motion which is compoimd- c'd oi thefe two motions ; or it is a motion in the dia- gonal of the parallelogram, of which thefe motions are the lldcs. This is called the Composition of Forces. The forces which produce the motions alonpj the fides of the parallelogram are called the Simple Fokces, or the CoNSTiTtJENT FoRCEs ; and the force which would alone produce the motion along the diagonal is called the Compound Force, the Ri;sui.ting Forci;, the Eo^uivALtNT Force. On the other hand, the force which produces a mo- tion along any line whatever, may be conceived as rc- fulting from the combined a(3iun ot two or more for- ces. We may knoiu or obfcrve it to be fo ; as when «e fee a lighter diagged along a canal by two horfcs, one on e?ch fide. Each pulls the boat directly toward him- felf in the direction of the track-rope ; the boat cannot go both ways, and its real motion, whatever it is, re- fults from this combined adion. This might be pro- duced by a fingle force ; for example, if the lighter be dragged along the canal by a rope from another lighter which precedes it, being dragged by one horfe, aided by the helm of the foremoft lighter. Here the real force is not the refulting, or the compound, but the equivalent force. This view of a motion, mechanically produced, is called the Resolution of Forces. The force in the diagonal is faid to be rtfohed into the two forces, haing the direftions and velocities reprctented by the fides- This praftice is of the moll cxteniive and niul- tifareous ufe in all mechanical difquifitions. It may fiequently be exceedingly difficult to manage the com- plication of the many real forces which concur in pro- ducing a phenomenon ; and by fubftituting others, whofe combined eflTedts are equivalent, our invelligatlon inav be much expedited. But more of this afterwards. We muft carefully remember, that when the motion AD is once begun, all compofition is at an end, and the motion is a fimple motion. The two determina- tions, by one of which the body would defcribe AB, nnd by the other of which it would defcribe AC, no longer co-exijl in the body. This was the cafe only in the hiJJr.iit, in the very a6l of changing the motion AB into the motion BD ; yet is the motion AD equiv.ilent to a motion which is produced by the aSual compofttui of two motions AB and AC ; in which cafe the t«o motions co-exift in every point of AD. Accordingly this is the way in which the compofi- tion of forces is ufually illuftrated, and thought to be demonftrated. A man is fuppofed (for inllance) to walk uniformly from A to C on a flieet of ice, while the ice is carried uniformly along AB by the ftrcam. The man's real motion is undoubtedly along AD ; but this is by no means a demonftration that the inftanta- Tieous or fhort-lived aftion of two forces would pro- duce that motion ; the man muft continue to exert force in order to walk, and the ice is dragged along by the ftream. Some indeed exprefs this proof in another way, faying, let a body defcribe AB, while the fpace in which this motion is performed is carried along AC. S'^S 47 TJfuai de- moiiftra. tion incon cluCve. . The ice may be carried along, and may, by friAio;i, or ^•■<^"ndLsw otherwife, drag" the man along with it ; but a fpace "' ''^'°''°"; cannot be removed from one place to another, nor, if ' it could, would it take the man with it. Should a ftiip dart fuddenly forward while a man is walking ucrofs the deck, he would be left behind, and fall to- ward the Hem, We mui\ fupl>ifi a tranfverfe force, and we wuil /til>j>o/e the compof.tion of this force «ith- out proof. This is no demonHratioii. We ai'prehciid that the demoiiilrdtion given above of this fundamental propufition is unexce])lionablc, when the terms force and dcfitdi'on arc ufcd in the ab- ftrad fenfe which we have affixed to them j and we ho[>e, by thefe means, to maintain the rigour of mathe- matical difculfiou in all our future difquilitioiis on thefe fubjcAs. The only circunnlance in it wliich can be the fubjccl of difcuflion is, whether we have fdeded the proper meafure and chnrafteriilic of a change of motion — We never met with any objtdion to it. But fome have fliU maintained, that it does not evi- objc«ions dently appear, from thefe principles, that the motion tn tlic de- which refults from the joint adion of two natural "."'"'^"" powers, whofe known and mealurable intenfiti^-s I'ave """'"[['^jn the fame proportions with AB and BC, and which alio not srily"to exert themfelves in thofe direftions, will produce a mo- ireffurcj, tion, having the direftion and proportion of AD. They will not, if the velocities produced by thefe forces are not ill the proportion of thofe intenfities, but in the fubdupUcate ratio of them. Nay, they fay, that it is not fo. If a body be impelled along A C by one fpring, and along A B by two fprings- equally llrong, it will not defcribe the diagonal of a parallelogram, of which the fide AB is doniile the fide AC. Nay, they add, that an indefinite number of examples can be gi- ven where a body cJoes not defcribe the diagonal of the parallelogram by the joint action of two forces, which, fcparately, would caufe it to defcribe the fides. And, lailly, they fay that, at any rate, it does not appear evident to the mind, that two incitements to motion, ha- ving the direftions and the fame proportion of intenii- ty with that of the fides of a parallelogram, actually generate a third, which is the immediate caufe of the motion in the diagonal. An equivalent force is not the fame with a refulting force. Yet we fee numberlefs cafes of the compofition of incitements to motion, and they feem as determinate, and as fufeeptible of being combined by compofition, as the things called moving forces, which are meaiured by the velocities : we fee them actually fo combined in a ihoufand inflances, as in the example already given of a lighter dragged by two horfcs pulling in different direAions. Nay, expei-imcnt (hews, that this compo- fit ion follows precifely the fame rule as the compofition of the forces which are mcufured by the velocities ; for if the point A (fig. i .) be pulled by a thread, or pref- fed by a fpring, in the diredion AB, and by another in the direction AC, and if the prefluies are prooor- tional to AB and AC, then it will be withheld from moving, if it be pulled or preffed by a third force, act- ing in the direftion A d, oppofite to AD, the prefTure being alfo proportional to AD. This force, afting in the diredion h.d, would certainly withftand an equal force afting in the direftion AD ; therefore we mull conclude, that the two preffures AB and AC really generate a force AD. This uniform agreement llicws 3 T 2 , that 19. 5i6 Stco-.idl.aw that the compcfition is dediiclb'e from fixed principles ; of Mi>ti.;ii i^^ij jf ^jQ^g ^p( appear that it can be heW as dcinoii- * rtrateil by the arguments employed in the cale ot mo- tions. A demon Itration of the compofition of pref- fures is dill wanted, in order to render mechanics a de- monllrative fcience. This com- Accordingly, philofophcrs of the firft eminence have pofition is turned their attention to this problem. It is by no ofmorcdif- miaiiseal'y; being fo nearly allied to firil principles, that ligation "=^ mull be ditficiilt to hnd axioms of greater fimplicity by which it inay be proved. ' Mechanicians generally contented themfelves with the folution given by Arirtotle ; but this is merely a compolition of motions : indeed he does not give it tor any tiling elie, and calls it " > fuppuftd to produce. (A) If two equal and oppofite preffures or incite- ments to motion art at once 011 a material particle, it fuffers no change ot motion ; tor it it yields in cither dire6\ion by their joint adlion, one of the preffures pre- vails, and they are not equal. Equal and oppofite preffures are faid to balance each other ; and fuch as balance muft be efteemed equal and oppofite. ( B) li a and i are two magnitudes of the fame kind, proportional to the inLenfities ot two prefiurcs which aCt in the fame direilion, then the magnitude , com- pofe the force AF. Thefefore the forces AG, AH, A g. Ah, acting together, are equivalent to the forcci AE, AF' ading together. But AG, A^ compofe a force = 2 Al ; and the forces AH, A h compofe a force =: 2 AL. Therefore llie four forces ading to- gether are equivalent to 2 AI -f- 2 AL. or to a; AK. But becaufe AO is i AE, and the lines G^, O 0, H h, are evidently parallel, 4 AK is equal to 2 AQ, or to AC ; and the propofition is demonlhTted. (I) Cor. Let us now f'uppofe, that by continual bi- fedion of a light angle we have obtained a very fiiiall angle a of a rhombus ; and let us name tl-.e rhombus bv, the multiple of a which forms its acute angle. The propofition (G) is true of a, 2 a, 4 «, &c. The propofition (H) is true of 3 a. In like ma;i! er, be- caufe (G) is true of 4 « and 8 a, propofition (H) is true oi 6 a ; and becaufe it is true of 4 a, 6 a, and 8 a, it is true of 5 a and 7 a- And (o on continually till, we have demonflrated it of every multiple of a that is lefs than a right angle. (K) Let RAS (fig. 5.) be perpendicular to AC,. 5^7 Secondl.aw of Moiion. 5i8 D Y N A SecondLiWgnd ]et ABCD be a rhombiid, whofc acute angle BAD of M . tion. jg ^yj^g multiple of 2 ^ tliat is lefs than a right angle. Let A b c i/he anoiher rhtnnbus, whofe fides A i, A d bifea the angles RAB, SAD. Then tlie forces A *, A d compofe a force AC. Draw t R, rt'S parallel to B A, DA. It is evident, that AR ^ B and AS d D are rhombufes, wliofe acute angles are multiples of a that are each lefs than a right angle. Therefore ( I) the forces AR and AB compofe tlie force A /', and AS, AD compofe A d ; but AR and AS annihilate each other's efl'cil, and there remains oidy^he forces AB, AD. Therefore A i and A d are equiva- lent to AB and AD, which compofe the force AC; and the propofition is demonftrated. (L) Cor. Thus is the corrollary of laft propofition extended to every rhombus, whofe angle at A is fome multiple of a lefs than two right angles. And iince a may be taken lefs than any angle that can be named, the proportion may be conhdeved as demonllrated of every rhombus : and we may fay, (M) 7''UJo equal forces, inclined to each other in any angle, compofe a force ivhich is meafured by the diagonal of the rhombus, luhofe fides are the meafures of the conjli- iuent forces . (N) Two forces AB. AC (fig. 6), having the di- reftion and proportion of the fides of a rectangle, com- pofe a force AD, having the direftion and propouion of the diagonal. Draw the other diagonal CB, End draw EAF pa- rallel to it ; draw BE, CF parallel to DA. AEBG is a rliomhus ; and therefore the forces AE and AG compofe the force A B. AFCG is alio a rhora- bus, and the force AC is eciuivalent to A F and AG. Therefore the forces AB and AC, afting togetlier, are equivalent to the forces AE, AF, AG, and AG ac- ting together, or to AE, AF, and AD acting toge- ther : But AE and AF annihilate each other's aCllon, being oppofite and equal (for each is equal to the half of BC). Therefore AB and AC ading together, are equivalent to AD, or compofe the force AD. (O) Two forces, which have the direction and pro- portions of AB, AC (fig. 7.) the fides of any paralle- logram, compofe a force, liaving the direction and pro- ■portion of the diagonal AD. Draw AF perpendicular to BD, and EG and DE perpendicular to AC. Then AFBG is a reftangle, as is alfo AFDE ; and AG is equal to CE. Therefore (N) AB is equivalent to AF and AG. Therefore AB and AC adting to- gether, are equivalent to A F, AG, and AC acting to- gether; that is, to AF and AE aetiiig together ; that is (N) to AD; or the foices AB and AC compofe the force AD. * Hence arifes the moft general propofition. If a material particle be urged at once by Inji'O preffures or incitements to motion, ivhofe intenfiiies are proportional incitements'" the Jides of any parallelogram, and ivhich a8 in the di- to motion. reBions of thofe Jides, it is oJfeSed in the fame manner as if it ivert n3ed on by a Jingle force, ivhofe intenfity is mea- fured by the diagonal of the parallelogram, and ivhich alls in its diredion : Or, two prejfurcs, having the direSion and proportion of the Jides oj a parallelogram, generate a prejfure, having the direSion and proportion of the diagonal. Thus have we endeavoured to demonilrate from ab- ftradl principles the perfeft firailarity of the compofition .St Compofi. tion of all M I C S. of prtlTures, and the compofition offerees r.^fafured by Sccondl.aw, the motions which they product. We cannot help be- ° ^' "'i"n. ing oi tlic opinion, tliat a (epurate denionllration is in- difpenfably necelfary. What may be fairly deduced Seeming from the one cafe, cannot always be aj)plied to the diiJcieiics other. No compofition of preffures can explain the"' ' ."^'""" change produced by a defltfting force on a motion al-moti'mand ready exilting ; for the changi;ig prefTure is the only of prelTure one that exills, and there is none to be compounded 'lifappear with it. And, on the other hand, our notions and ob-"', " '^"*- iervations 01 the CDnipolition or motions will not explain [j^jp^j the compofition of preffures, unlefs we take it for grant- ed that the preffures are proportional to the velocities ; but this is perhajis a gratuitous affumption. At any rate, it is not an intuitive propofition; and \n e have mentioned fome fa-Ss where it leems that they do not follow the fame proportion. The pieffure of four equal fprings produces only a double velocity. It would ap- pear, therefore, that there are circumiiances which ob- lige us to fay, that the exertion of prefTure, as a caufe of motion, is not (always at kail) propoitional to tlie real mcafurahle prefTure, We are therefore anxious to dif- cover in wliat the difference confills ; and in the mean time muft allow, that tlie prefTure exerted on a body at refl. is different from its exertion in producing motion. We cannot indeed flate any immediate comparifon be- tween prefTure and motion, nor have we any clear con» ception of the conneCtiini between them. It is only by our fenfationsof touch that we have any notion of prcl- fure, and it is experience that teaches us that it always accompanies every caufe of motion. We can, however, obferve the proportions of prelTures, and compare tliem with the proportions of motion. We very often ob- ferve them difl'erent ; and therefore it was imlifpeiifably neceflary to invefligate the laws of combined prefiure as v/e did the laws of combined motion in confequeiice of prefTure. Yet we fhould err, if we haffily ailerted that preflures are not proportional to the motions which they produce ; all that we are intitled to call in doubt is, whether the preffures in their exertion, while they actually produce motion, or changes of motion, con- tinue to he the inme as when they do not produce motion, being withltood or balanced by oppofite pief- fures. Confidered as cauies of motion, we ought to think that they do not vary while they produce mo- tion, and that the adtual prefiure, while it produces a double motion, is really double, altliough it may be quadruple when the body exerting it is made to act on a body that it cannot move. We are confirmed in this opinion by obfcrving, that other fadts fhew us, that even while producing motion, the prefTure which we call quadruple, becaufe we have meafured it by four equal preffures balancing it, is really quadruple, confidered as the caufe of motion, and produces a quadruple motion. A bow which requires four times the force to draw it to any given extent, will communicate the fame velocity to a bundle of four arrows that a bow four times cafier drawn communicates to one arrow, and will therefore produce a quadruple motion. Yet it will only produce a double velocity in the arrow that acquired a fimple velocity from a bow having one fourth of the flrength. Thefe difcrepancies fhould excite the endeavours of' mechanicians to invefligate the laws obferved in the ac- tion of preffures in producing motion. Had this been done with care and with candour, we fhould not have had DYNAMICS 519 Wor.dl.a-.v had the nreat difference of opinion, which ftlU divides times weaker how, which giver, the arrow only half the SccomlLaw f Mof'on. pi,|]Q(-„pj,^,r5^ about the meafiires of moving forces. But velocity ; and thjs has the diferepancy between tlic ef- °' ^l""""- ""^ ;i j'pirit of party, which had arifeii from other eaufes, fefts of prellures and of our ablbatt moving forces en- ' gave importance to what was at firft only a difference tirely difappcared. For this circumffance of the diffe- of exprclTion, and made the partifans of Mr Leibnitz rence in the time of acling will be found, on ftrift ex- avail themfelves of the figurative language which has amination, in all tlie cafes of the change of motion by done fo much harm in all the departments of phllofo- prelfures which we meafure by their effedls on a body phy. Notwilhftanding all our caution, it is hardly pof- at rell. AVhen this and the appreciable changes of ac- iible to avoid metaphorical conceptions when we em- tual preffure, during the time of producing the motion, ploy the language of metaphor. The abettors of the are taken into confideration, all diiftrerce vauifhes, and Leibnitziaii mcafure of n'oving forces, or perhaps, to the compofition of prefTures is in perfeC-l harmony with fpeak more properly, the abettors of the I.eibnilz.ian the compofuion of motions, or of ablbaft moving for- meafure of tliat force which i; fuppofed to preferve bo- ces. Dynamics Is thus made a dtmonltrativc fcience, dies in their coiulition of mention — infill, that the force and affords the opportunity of inveiligating, by obfer- which is exerted in producing any change of motion is vation and experiment, the nature of thofe mechanical greater in proportion as tlie motion changed is greater: powers which refide in bodies, and which appear to us and they give a very fpecions argument for their affer- under the form of preiTurc, inducing us to cor.fider pref- tion. Tliey njipeal to tiic exertions which we our- lure as a caufe of motion. ftlves make. Here we are confcious of the faiSl. Then In this, however, we arc rather inaccurate. Preffure they give fimilar examples of the aftion of bodies. A is one of the fenfiblc effedls of that property which is clay ball, moving fix feet per fecond, will make the ad- alfo the caufe of motion. It is not the preffure of a dition of one foot to the velocity of an equal clay ball piece of lead, but its htavinefs, that is the reafon that that is already moving four feet per fecond in the fame it gives motion to a kitchen jack. Preffure is merely diredlion. But if tiiis lull ball be already moving ten a generic name, borrowed from a familiar inftanee, and feet per fecond, we mufh follow it with .a velocity of given to moving forces, which have the fame nature, twelve feet in order to increale its velocity one foot, but different names that ferve to mark their connection But, without inlifting on the numberlefs paralogifms with certain fubllanc.;.-., in v% hich they maybe luppoled and inconfiftencies which this way of csnceiving the to relide. Natural philofophy is almoft entirely cm- matter would lead us into, it fufHces to obferve, that ployed in examining the nature of thcfe various pref- the phenomena give us abundant afiTurance that there fures or accelerative forces ; and the general doctrines has been the fame exertion in both thefe cafes. This of dynamics, by afcertaining what is common to them acceleration is always accompanied by a comprefiion of all, enable us to mark with preeifion wh.at is charadter- the balls, and the comprclTion is the fame in both. This illic of each. We have now advanced very fir in this in vefligat ion; General co- for we have obtained the criterion by which we learn rollaries. the direftion and the mtpgnitude of every changing force : and, on the other hand, we fee how to ftate what will be the effeft of the exertion of any force compreffion is a very good meafure of the force em- ployed to produce it ; and in the prcfent cafe, we need net even trouble ourfelves with any rule for its meafure- ment : for furely when the comprefTion is not different, but the fame, the force exerted is the fame. This is farther confirmed by obferving, that it requires the fame that is known or fufpefted to aft. All this we learn by the compofition of forces ; and the greatefl pait of me- chanical difquiHtion confifls in the applioation of thij doftrine. For fuch rcafons it merits minute confider- ation ; and therefore we mufl point out iome general conclufions from the properties of figure, which will greatlv facilitate the ule of the parallelogram of forces. 1. The conflituent and the refaking forces, or the fimple and compound forces, act in the lame plane ; for the fides and diagonal of a parallelogram are in one plane. 2. The fim.ple and the compound forces are propor- force to make the fame pit, or to give the fame mo- tion, to a piece of clay lying on the table of a (flip's cabin, whether the Ihip befalling two miles or ten miles per hour. Thu.'i we fee that there are ftrong reafons for belie- ving, that the exertions of preffure in producing motion, or that the preffures aduully exer'ed, are proportional to tiie changes of motion obferved, and that they coincide in this refptit with our abilract conceptions of moving forces. But we have ftill better arguments. None of the Leibnitzians think of denying the equal exertions of tional to the fides of any triangle wliich are parallel to gravity, or of any of thofe powers which they call_/o/i- their directions. For if any three lines, ab. Id, ad, be citations or accelerating forcis. They all admit, that drawn paralhl to AB, AC, and AD (fig. 7, n"^ z.), 54. 55- gravity, or any conltant accelerating force, produces equal increments of velocity in equal times, and that a double gravity will produce a double increment in an equal time, and an equal increment in half of the time ; and that a quadruple gravity will produce a double ve- they will form a triangle fimilar to the triangle ABD. For the fame reafons they are proportional to the fides of a triangle a't/'d, wliich are refpedftively perpendicular to their direftions. 3. Therefore each is proportional to the fine of the loeity in half the time. All thefe things are granted oppofite angle of this triangle ; for the fides of any tri- by them, and their writings are full of reafonings from angle are proportional to the fmes of the oppofite this principle. Now from the fadt, acknowledged by angles. the Leibnitzians, that the quadruple force of a bow 4. Each is proportional to the fine of the angle con- gives a double velocity to the arrow, in every inftant tained by the direftions of the other two ; for AD is of its adtion, it indifputably follows, that it has afted to AB as the fine of the angle ABD to the fine of on it only for half the time of the aftion of. the four the angle ADB. Now the fine of ABD is the fame with J6 57' 52-0 .Secoiiill.aw of Moii »ii. 58 Sonic fpe- cial uTc^ uf ih^ paral- lel' pram of, forces. DYNAMICS. 59 'Equivalent of many forces. ■piateXXlI tfo. with the fine of BAC contaiiu'J between the dircftions AB and AC, and the fine of ADB is the fame with the fine of CAD ; alfo AB is to AC, or BD, as the fine of ADB (or CAD) to the fine of BAD. We now proceed to the apph'cation of this funda- mental propofition. And we obferve, in the firft place, that fince AD may be the diagonal of an indefinite juimber of parallelognims, the motion or the prefi"in-e AD may rcfult from the joint aftion of many pairs of forces. It may be produced by forces which would fcparately produce tlie motions AF and AG. Tin's -generally jjives us the means of dlfcovcring the forces which concur in 'ts pr(?tiu^) : now AD and DA balance each other. This corollarj' enables us to Am- plify many intricate complications of force; it alfo ena. bles us to draw accurate concliifions from very imper- feft obfervations. In moft of our praftical difcufiions we know, or at lead we attend to, a part only of the forces which are atting on a material narticle ; and in fuch cafes we reafon as if we faw the whole : yet is our mathematical reafoning good with rcfpcft to the equi- valent of all the parcels which we are contemplating, and the equivalents of the fmaller parcels of which it confifts ; and the negleftcd force, or parcel of forces, induces no error on our conclufions. In the fpontaneous phenomena of nature, the invefli- Expedition gation and difcovery of our ultimate objeft of fearch is^iethidsfor frequently ver)' difncult, on account of the '""Itiplicity °|^ '^" ^ ''|^. of direftions and intenfitics of the operating forces or int.. motion motions. We may generally facilitate the procefs, by in ci mpli- fubftitutrng equivalent forces or motions afling in con-"'^'^ '•^''^ venient dirtftions It is in this way that the naviga- tor computes the fhip"s place with very little trouble, by fubilituting equivalent motions in the meridional and equatoreal direftions for the real oblique courfes of the fhip. Inftead of fetting down ten miles on a courfe, S. 36. 52. W. he iuppofes that the fliip has failed eight miles due fouth, and fix miles due weft, which brings her near to the fame place. Then, in- ftead of fourteen miles fouth-weft, he fets down ten miles fouth and ten miles wcil ; and he proceeds in the fame way for every other courfe and dillance. He docs this expeditiouflv by means of a traverle table, in which are ready calculated the meridional and equato- real fides of right angled triangles, correfponding to every courfe and diftance. Having done this for the courfe of a whole day, he adds all the fouthings into one fum and all the weftings into another: he confiders thefe as forming the fides of a right angled triangle ; he looks for them, paired together, in his travtrfe ta- ble, and then notices what angle and what diftance cor- refponds to this pair. This gives him the pofition and magnitude of the ftraight line joining the beginning and end of his day's work. The «,^ D Y N A Ci-ironiU-aw Ttie miner pToce«j9 in the fame way when he takes t}( Motion, jjij, p[^j, q( fubterraneous workiii;^?, mealuring, as he • goes along, and noticing the bearing of each line by the compal's, and fctting down, from his traverfe taUe, the ncihing or fouthiiig, and the calling or weiliiig, for each oblique line : but there is anotlier circumflance which he muil attend to, namely, the Hope of the va- rious drifts, galleries, and other workings. This he does by noting the rife or the dip of each flopiug line. He add"! all thefe into two funis; and taking the riiings from the dips, he obtains the whole dip. Thus he karns how far the workings proceed to the north, how ■far to the call, and how far to the dip. The refle^Sling reader will perceive that the line join- ing the two extremities of this progrelTion will form the diagonal of a redlangular parallcloplped ; one of •whofe fides lies north and fouth, the other lies eafl. and weft, and the third is right up and down. The mechanician proceeds in the veiy-fame way in the inveftigatitm of the veiy complicated phenomena *-h!ch frequently engage his attention. He confiders every motion as compounded of three motions in fome •convenient direflions, at right angles to each other. He alio confiders every force as refulting from the joint adion of three forces, at right angles to each other, and takes the fum or difference of thefe in the fame or oppofite direftions. From this procefs he ob- tains the three fides of a parallcloplped, and from thefe fomputcE the pofition and magnitude of the diagonal. This is the motion or force refulting from the compoli- tion of all the partial ones. Forces may This procedure is called the Estimation or Re- H 1 "' *' Dt;CTioN of motions and forces. icduced to -^ motion or force AB (fig. 9.) is faid to be ejli- 64 mated in the direftion EF, or to be reduced to this di- A Riven di- reftion when it is conceived as compounded of the mo- tions or forces AC, AD, one of which AC is paral- lel to EF, and the other AD is perpendicular to it. This expreflion is abundantly fignificant ; for it is plain that the motion AD neither promotes nor hinders the progrefs along EF, and that AC exprefles the whole progrefs in this direftion. In like manner, a force AB (fig. lO. ) is faid to be ejlimated in, or reduced to, a given plane EFGH, when it is conceived as refulting from the joint aftion of two forces AC, AD, one of which is parallel to a line a b drawn in that platic, and the other j\D is perpendicu- lar to it The pofition of the line a b is determined by letting fall B b perpendicular to the plane, and draw- ing i P to the point P, in which BA meets the plane; then A a being drawn parallel to B b, will cut off b a, which is the redudlion of the motion AB to the plane. Drawing • C parallel to a b, and completing the paral- lelogram ACBD, it is evident that the motion AB is equivalent to AD and AC, which is parallel to a b, and the three forces AB, '\C, AD, are, as they Ihould be, in one plane perpendicular to the plane EG. If three forces /iB, .AC, AD (fig. 11.), are in equilibrio, and are reduced to any or>e diredlion d A. l,or to one plane EFGH, the reduced forces are alio in equilibrio. Fi'Jl, Liet them be reduced to one direftion d / by drawing the perpendiculars B /', C r, D d ; make AL equal to AD, and join BL, CL, and draw the perpen- diculars L /, C £ ; then, becaufe the forcts AB, AC, Suppt. V01-. I. Part II. rca. «5 Or a given reducrd. M I C S. 521 AD, are in e L i, are all parallel, being perpendicular to the plane ; therefore the planes AB r- x and CL xk are parallel, and ,,3, , x, are parallel. For fimihr rea- ions ;3 X. a y, are parallel ; theretore a^x, is a parallelo- gram. Alfo, becaufe the linesD /, A a, L a, are parallel, and DA is equal to AL ; therefore s x is equal to « x. But becauie a3x« is a parallelogram, the forces «'?, a «, are equivalent to r >. ; and o / is equal and oppofiie to a \, and will balance it ; and therefore will balance « 5 and ay., which are the redutlions of At5 and AC to the plane EFGH, while a f ii the redudion of AD j therefore the propoGtion is demoaftrated. The moft ufual and the mod ufeful mode of rednc The n^cft tion is to ellimate all forces in the diredions of three "f'-f"' "•"'• lines drawn from one point, at riiiht anirles to each".' ^"'"'^* other, like the three plane angles of a redangular chelt, th^ir co or- forming the length, the breadth, and the depth of thedmaccs. cheft. Thefe are commonly called the three co crdi- nates. The refulting force will be the diagonal of this paralltlopiped. Th;s procefs occurs in all difquifitions in which the mutual adion of folids and fluids is confi- dered, and when the ofcil'.ation or rotation of detached free bodies is the fubjed of difcuffion. , The only other general theorem that remains to be Rci3,i,j deduced from this law of motion is, that if a number morlovs of ofboiliesare moving in any manner whatever, and an '".''"' ""' equal force ad on every particle of matter in the fame^"'^'"''^'^ ^^ 11 I J- n- 1 • > • • -,, ^ ^ any extra, or parallel dnedions, their rclaLive motions wd! fufferreoiu. .qual no change ; for the motion of any body A (fig. i 2.), -n.! parallel relative to another body B, which is alio in motion, is''^'"- compounded of the real motion of A, and the oppofite to the real motion of B ; for lot A move uniformly from A to C, while B defcribes BD uniformly, draw AB, alfo draw AE equal and parallel to BD, join EC, DC, ED. The motion of A, relative to B, confift* in its change of pofition and diftance. Had A defcri- bed AE, while B defcribed BD, there would have been no change of relative place or dillance ; but A is now at C, and DC is its new diredion and dillance. The relative or apparent motion of A therefore is EC. Complete the parallelogram ACFE ; it is plain that the motion EC is compounded of EF, which is equal and parallel to /VC, the real motion of A, and of EA, the equal and oppofite to BD, the real motion of B. Now let the motions of A and B fuHain the fame change ; let the equal and parallel motions AG, BH,, be comp(«inded with the motions AC and BD ; or let forces acl at once on A and B, in the parallel diicdi.)ns AG, BH, and with equal intenfitics ; in cither fnppo- fition, the refulting motions will he A c^ B d, the dia- gonals of the parallelograms A G c C, and B H ^ D. Conllrnd the figure as before, and we fee that the re- lative motion is now e c, and that it is the fame with EC both in refped of magnitude and pofition. Here we Hill fee the conllant analogy between the compofition of motions and the coinpoiition of foicts. 3U la 522 D Y N A SecondLawJn the firft cafe, tlie relative motions of things are not ^'^ J^"'"'"', changed, whatever common motion be compounded ' with them all ; or, as it is ufiidly, but inaccurately, cx- prefil'd, although the fpace in which they move be car- ried along \,vith any motion whatever. In the fecond cafe, the relative niotions and adions are not changed by any external force, however great, when equally ex- erted on every particle in parallel directions. Thus it is that the evolutions of a fleet in a uniform current are the fame, and produced by the fame means, as in ilill water. Thus it is that we walk about on the furface of this globe in the fame manner as if it neither revolved round the fun, nor turned round its axis. Thus it is that the fame ilrength of a bow will communicate a certain velocity to an arrow, whether it is (hot call, or weft, or north, or fouth. Thus it is that the mu- tual a£iions of fublunary bodies are the fame, in what- ever dircdlions they are exerted, and notwithilanding the very great changes in their velocities by reafon ot the earth's rotation and orbital revolution. I'he real velocity of a body on the earth's equator is about 3000 feet per fecond greater at midnight than at midday. For at midnight the motion of rotation nearly confpires with the orbital motion, and at midday it nearly oppofes it. The difference between the velocities at the begin- ning of January and the beginning of July is vailly greater. And at other times of the day, and other fea- fons of the year, both motions of the earth are tranf- verfely compounded with the eafterly or wefterly motion of an arrow or cannor. bullet. Yet we can obferve no £9 change in the effefts of the mutual aftions of bodies. Thisaffords This is an important obfervation ; becaufe it proves a demon- that forces are to be meafnrcd by no other fcale than llration of , ^^ motions which they produce. We have had re- the proper- ' , ^ .' '^ , ..„ ,,. tionality of pf^ted occahons to mention tlie very ditterent eitima- n-oving tion of moving forces by Mr Leibnitz ; and have fliewn forces to how, by a very partial confideration of the aftion of produced"' '^°^'^ natural powers called prejfura, he has attempted by them to prove that moving forces are proportional to the fquares of the velocities; and we Ihewed briefly, in what manner a right confideration of what paffes when mo- tion is produced by meafurable preffures, proves that the forces really exerted are as the velocities prodixed. But the moil copious proof is had from the prefcnt ob- fervation, that, in fail, the mutual aftions of bodies de- pend on their relative motions alone. , J •' •_. The Leibnitzian m.eafure of moving force is altoge- compatible ther incompatible with the univerfal faift now mention- wjth their ed, '!•(=.. that the relative motions of bodies, refulting proportion- f^jj^ their mutual aftions, are not afFefted by any com- fquarcs of ''"'°" motion, or the aftion of any equal and iiarallel force thofe mo- ^n both bodies- for this univerfal faft imports, that »iont. when two bodies are moving with equal velocities in the ', fame diieftion, a force applied to one of them, fo as to '■■ . jncreafe its velocity, gives it the fame motion relative to the other, as if both bodies had been at reft. Here it is plain that the fpace defcribed by the body in con- fciiuence of the primitive force, and of the force now added, is the fum of the fpaccs which each of them would generate in a body at reft. Therefore the forces are proportional to the velocities or changes of motion which they produce, and not to the fquares of thofe ve- locities. This meafure of forces, or the pofition that a force makes the fame change on any velocity what- ever, and the dependence of the relative motions on any (notion that is the fame on all the bodies cf a fyf- M I C S. tem, are counterparts of each other. Since this indc- f'erondl j*^' pendence is a matter of obfervation in all terreltrial bo- "f Mo'icn. ' dies, we are intitled to fay, that the powers which the • ' Author of Nature has imparted to natural bodies are no way different from what are competent to matter once called into exiftence. .\nd it alfo follows from this, that we muft always remain ignorant of the abfo- lute motions of bodies. The faft, that it has required the unremitted ftudy of ages to difcover even the rela- tive motions of our folar fyftem, is an argument to prove that the influence of this mechanical principle extendi far beyond the limits of this fublunary world ; nor has any phenomenon yet been exhibited wliich Ihould lead us to imagine that it is not univerfal. When we have made ufe of thefe arguments with SnBeircvl- fome zealous partizans of Mr Leibnitz's doftrine, they '»'* deforce have anfwered, that if indeed this independence of the' ,,"'"''• relative motions of terreftrial bodies were obferved to ^Jj^'|',■!^".'* obtain exattly, it would be a conclufive argument. Butfurce. the motion with which all is carried along is fo great iji comparilon with the motions which we can produce in our experiments, that the fmall additions or diminu- tions that we can make to the velocity of this common motion muft oblerve very nearly the proportions of the additions or diminutions of their fquares. The difte- rences of the fquares of 2, 3, and 4, are very unequal ; but the differences of the fquares of 9, 10, 11, are much nearer to the ratio of equality ; and the differen- ces of the fquares of locoooi, ICOOO02, 100Q003, ^'^ not fenfibly deviate from this ratio. But it is not faft that we cannot produce motions which have a very fen- - fible proportion to the common motion. The motion of a cannon ball, dlfcharged with one-third of its weight of powder, is nearly equal to that of the rotation of the earth's equator. When, therefore, we difcharge the ball eaftward, we double its motion ; when to the weftward, we deitroy it. Therefore, according to I^eib- nitz, the aftion in the firft cafe is three times the ac- tion in the fecond. In the firft cafe it changes the fquare of the velocity (which we may call l ) from 1 to 4 ; and, in the fecond, it changes it from I to o. But fay the Leibnitzians, the velocity of rotation is but ^'^ of the orbital velocity of the earth, and our obferva- tions of the velocities of cannon bullets are not fuffi- ciently exaft to cnfurc us againA an error of ' — r' But the later obfervations on the peculiar motions of the fixed liars concur in fhewing, that the fun, with his at- tending planets, are carried along with a very great mo- tion, which, in all probability, has a fenfible ratio to the orbital motion of the earth. Tiiis muft make a prodigious change on the earth's abfolute motion, ac- cording as her orbital motion conlpires with, oppofes, or croflcs, this other motion : the earth may even beat abfolute reft in fome points of its orbit. Thus will the compofition with the motions produced in our experi- ments be fo vaiied, that cafes mujl occur when the dif- ference of the refults of the two meafures of force will be very fenfible. But, farther, they have not attended to the agree- ment of our experiments, when the difcharges of can- non are made in a direftion tranfverfe to that ot the common motion. Here the immenfity of the common motion, and the minutenefs of our experimental veloci- ties, can have no effeft in diminifliing the difference ot the refults of the two doftrines. This will appear dif- tinftly otion of fnrcc witli all o.ir ac curate oli- fcrvacii'is of the cx- errion^ ot natural powers. D Y N A Secnrdtaw u'nAly to every reader who is much converfant in dir. of Motioi. qui'fitii^ns of tills kind ; aTid it is in thefe more innde- ^""^^^"^ rate motions that the complete independence ot the re- lative motions on the common motions mull accurately appears. Pendulum clocks and watches have been of- ten executed whic'u do not deviate from pcrfedt e()uabi- litv of motion one part in 86400. This could not be ob- tained in all directions of the olcillations, if the torces de- viated from the ratio ot the velocities one part in 8(1400. Perfeft a- O" the whole, we inay conhdtfr it as eilablinicd on grccniLMUnf the fureft foundation, that the attion of thofe powers of the abftrad „-^,„-al bodies which we call prcjj'itrc, fiich as the foice of fprings, the exertions of animals, the cohelion of bo- dies, as well as the aftion of tliofe other incitements to iTiotion which we call attralilons and n-piilfoiis, fuch as eravitation, magnetiim, and eletlriclty — is proportional to the change of velocity produced by it. And we miift obferve here, that this is not a mere mode of con- ception, the refult of the laws of human thought, which cannot conceive a natural power as the caufe of motion otherwife than by its producing motion, and which cannot conceive any degiee of moving power dilFercnt from the degree of the motion. This is the abllraft doftrine, and is true whether the preflures are propor- tional to the velocities or to the Iquares of the veloci- ties. But we fee farther, that whatever is the prefTure of a fpring (for example) on a quiefcent body, yet the preffure aftually exerted in producing a double velocity is only double, and not quadruple, as our firil imperfeft obfervatlous make us imagine. Sir Ifaac Newton has added another propofition to tiurdl.iw of (jjj, number of laws of motion ; namely, that e-verv ac- fourded on '"" '■'' "-'^'""/"'""''^ by an equal and contrary reaction. But in af}h"mlng this to be a law of nature, he only means that it is an univrrlal fact : And he makes this affirmation on the authority of what he conceives to be a law of human thought ; namely, that thofe qua- lities which we find in all bodies on which we can make experiments and obfervations, are to be confidered as univerfal qualities of body. But we have limited the term /utu of motion to thofe confequeiices that necef- farily flow from our notions of motion, of the caufes of its produftion and changes. Now this third New- tonian propofition is not fuch a refult. A magnet is fald to aft on a piece of iron when, and only when, the vicinity of the magnet is obferved to be accompa- nied by certain m.otlons of the iron. But it by no means follows trom this obfcrvation, that the prefence of the iron fhall be accompanied by any motion, or anv change of flate whatever of the magnet, or any ap- pearance that can fuggefl the notion that the iron at\s on the tnagnet. When this was obferved, it was ac- counted a dlfcovery. Newton difcovercd that the fun afts on the planets, and that the earth afts on the moon ; and Kepler difcovered that the moon reafts on the earth. Newton had obferved that the iron re- afts on the magnet ; that the aftions of eleftrified bo- dies were mutual ; and that every adtion of fublunary bodies was, in faft, accompanied by an equal and con- trary' reaftion. On the authority of his rule of philo- fophizing, he affirmed that the planets reaft on the fun, and that the fun is not at reft, but is continual- ly agitated by a fmall motion round the general centre of gravitation. He pointed out feveral confequences tif this readion. Aftrunomers examiaed the celeftial 70 , [s noc a truili. M 1 C S. ^ 523 motions more narrowly, and found that thofe co;ifc-S;c"ndLaw quences do really obtain, and dillurb all the )jlanetai-y ,"' Moimn.^ motions. It is now found that this reciprocity of ac- * tlon obtains throughout the folar fyftcm with the uttnofl lyrecifion, and that the third Newtonian propofition is really a law of nature, although it is not a law of hu- man thought. It is a difcovery. The contrary in- volves no abfurdity or cotitradiftion. It would Indeed be contrary to experience ; but things nu'ght have been otherwife. It is conceivable, and poihble, thit a ball A Ihall flrike another equal Ijall B, and carry it along with it, without any dimluutlou of its velocity. The faft, that the velocity of A is reduced to one-half, is the indication of a force rcfiding in B, which force changes the motion of A ; and the intenfity of this force is learn- ed from the change which it produces. This is found to be equal to the change produced by A oa B. And thus the reaftion of B is difcovcred to be equal to the aftlon of A. It is highly probable, that this univerfality and equa- lity of reaftion to aftlon is the confequence of fome general principle, which v.'e may m time difcover ; meanwhile we are intitlcd to fuppofe it univerfal, and to reafon from this topic in our dilquilitions about the , aftions of bodies on each other. Although the celebrated philofophers of Europe (^3„ppr(„, have at lall agreed in the reception of the two propofi- N,Leihiiit«, tions fo largely difcuffed by us as the laws of motion, 2"^' other they have differed exceedingly in their opinion about ^!j"'°,* their origin and validity : Some afTerted that they areemertaincfl entirely matters of experience; while others affirmed very ioade- them to be neceflary truths. The royal academy of'l'.'^'"^ "P'- Berlin inade this queftion the fnbieft of their prize dif-"°"? ™",' I- • ■ 1 ««■ ii • ,- I ceniiiig the lertation m tlie year 1744. Mr iNlaupertuis, preiident f,,|,|,rja,ion of the academy, publllhed a diifcrtation ; in which heofthelav»j endeavoured to prove that they are neceflary truths, only °f motion, becaiife they arc fuch as make the quantity of adion the leafl pojfihle an economy which is worthy of infinite wifdoni ; and therefore certainly direfts the choice of the Au- thor of Nature. On thisiiccount alone are they necef- fary truths. But this is not the way to confider a queflion of this kind. We know too httle about infinite wifdom to be able to fay with Meifrs Leibnitz and Maupertuis, that the Deity fhould or fhould not imprels on bodies lav/s different from thoie which are eflfential to matter; and *we are not to inquire whether God could or could not do this. We know from our own experience, that matter, when fubjeiited to the aftion of intelligence, may be moved in a way extremely different from what it would follov>r if left to itfelf, and that its motions may either be regulated by fixed, but contingent, laws, or may be without any conflancy whatever, and vary in every inftance. When we fuppofe the exitlence of matter and motion, a variety of truths are involved in tlie fuppofition, in the fame manner as all the theorems in the third book of Euclid's Elements are involved in the conception of a circle and a flraight line. Our firft employment fhould be to evolve thofe truths. We can do this in no way but by firft noticing the relations of the ideas that we have of the different objefts of Con- templation, and then following the laws of human thought in our judgments concerning thofe relations. This procefs of the mind is expreffed in the train of a geometricid demonftration. The different parts or argu- 31/2 mentation* 524 SecondLaw of Motion. DYNAMICS. mentations of this train are not the eaufes of our con- changes in the motion ; and it Is not til} all aftion has Of Antre- cliifions, but the means by which we fc.rn our judge- ceafeil that the motion is brought to ilsoftcnfible (late, ''"''''<' and mcnt ; not the rcafons of the truth of our ultimate in which it is the ohjeift of our attention and our fu- "^^"''l conclufion, but the fteps by which wo arrive at the ture dilcufiions. Inftances of the eflefts of fuch con- 'j knowledge of it. The young geometer generally thinks tinned and fuch varied actions are to be feen in moil Dtherwife : But that tU'S is the matter of faft is plain of the phenomena of nature or art. The communica- from this, that more than one demonftration, and of- lion of motion by impulfe is perhaps the only inllance ten very different, can be given of the fame theorem, (very frequent indeed) that can be produced where this We muil proceed in the fame manner in the prefent is not neceffary : Nay, we Ihall perhaps find reafon to queilion ; and the firft general truths which we And in- conclude, that this inllance is not an exception, and that volved in the notions of matter, motion, and force, muft even the communication ot motion from one billiard be received as necejfary truths. The fteps by which we ball to another is brought about by an adlion conti- arrive at the difcovery are the laws of human thought ; nued for fomc time, and greatly varied during that and the exprclfion of the difcovery, involving both the time. Much preparation is therefore neccffary before truth itlVlf and the manner of conceiving it, is a necef- we can apply the general laws of motion to the folution fary law of motion. There may be other fafts, perhaps of moll of the qui ftions which come before us in the as general as any of thofe neccrfary laws, but yvhich do courfe even of our elementary difquifitions. We mull not necelfarily refult from the relations of our notions lay down fomc general piopofitlons which determine of motion and of force. Thefe are difcovered by ob- the refults of the continued, and perhaps varied, a6tions fervation only ; and they ferve to charafterife the forces of moving forces ; and we mull mark the different ef. which nature prefents to our view. Thefe fafts are feels of the fimple continuation of aftion, and alfo thofe coni'mgent laws of motion. of the variations in this cojitinued aftion, both in re- We apprehend that this method has been followed fpeft of intenfity and oirection. The effedl of a mere " " " ' ■ continuance of aftion mull be an acceleration of the motion ; or a retardation of it, if the force continue to adl in the oppofite direftion. The tffedl of the conti- nued aftion of a tranfverfc force mull be a continual defleftion, that is, a curvelinral motion. Thefe mull therefore now occupy our attention in their order. Of Accelerated and Retarded Motions. in treating this article. The firft propofition, termed a laiv of motion, is only a more convenient way of ex- prefiing our contemplation of motion in body as an ef- feft of the general caufe which we term force. The fe- cond propofition does nothing but exprefs more dif- tinftly the relation between this caufe and its effetl ; it expreifes what we mean by the magnitude and the kind of the caufe. The propofition, flating the com- pofition of forces, is but annther form of the fame law. All men can perceive, that a (lone dropped from _. '' better fuited to the ordinary procedure in geometrical the hand, or fliding down an uniform flope, has itSji^ntiji jj. difquifitions. motion continually accelerated, and that the motion ofpolkion if an arrow rifing perpendicularly through the air is con-".""' concep- These propofitions might have completed the doc- tinually retarded; and they feel no difficulty in concei- "°" " j ' trines of dynamics ; but it appears that, in order to ving thefe changes of motion as the eflefts of the con-^f 3 i,„^y the produftion of a material univerfe which fhould ac- tinual operation of their weight or heavinefs. The falling in refpeift coinplilh the purpofes of the Creator, it was neceffary ftone is in a different condition in rcfpedt of motion into'no"un.. that there be certain charafteriftic differences between the beginning and the end of its fall. In what rcfpeft do the forces inherent in the various colleftions of matter thefe ftates of the body differ? Only in lefpeft to what which compofe this univerfe. The fails or phyfical we call its ve/ocity. This is an affeftion of motion ; it laws (for the above-mentioned laws are metaphyfical) is an expreflion of the relation between the two notions of motion may be different from thofe which would or ideas which concur to form the idea of motion ; have been obferved had matter been left entirely to it- namely, the fpace and the time. Thefe are all the cir- felf. This difference may have introduced other laws cumllances that we obferve in a motion. Time elapfes, of motion as necelfarily refulting from the nature of and during its currency a fpace is defcribed. The term velocity expreffes the magnitude of the fpace which correfponds to fome unit of time. Thus, the rate of a fhip's motion is determined, when we fay that it is nine miles in an hour, or nine miles per hour. AVe fome- the forces. We have occaiionally itientioned lome in- flances where this appears to obtain, but gave good rea- fons for affirming, that a due examination of all circum- ftances which may be obferved in the produftion or va- riation of motion by thofe forces, has demonflrated that times fay (but aukwardly) " The motion is at the rate, there are no fuch deviations from the two laws of mo- or with the velocity, of a mile in three days." It is moft tion already determined, but that all the mechanical conveniently expreffed by a number of fome given units powers of bodies, when confidered merely as eaufes of of length, which completely make up the hne defcribed motion, aft agreeably to the fame laws Careful exa^ mination was, however, faid to be nccelfary. This examination mull confift in dillinftly noticing the clrcumllances that occur in the produftion of mo- tion by any force whatever. It is by no means enough during this unit of time. But the mechanicians ex- prefs it in a way more general by a fraftion, of which the numerator is a number of inches, feet, yards, fa- thoms, or miles, and the denoijiinator is the number of feconds, minutes, or hours, employed in moving along to ilate finiplv the intenfity of the force and the direc- this line. This is a very proper expreffion ; for. when tion of its exertion. If a force continue to aft, it con- we fpeak of any velocity, and continue to reaion from tinucs to vary the motion already produced. Should it, we conceive ourfelves to fpeak of fomething that re- the- force change its intenfity or direftion while it is mains the fame, in the different occafions of ufing the afting, thefe circumflances muft induce ftill farther term. Now if the velocity be eonftant, it is indifferent how DYNAMICS. ef Acccle- how long the line may he; bccaufe the time of its dc- Axiom. — If A be to B in a ratio that is greater than ratcil and jcrjptioi) will be Icngtheiifd in the fame proportion, any ratio lifs than that of C to D, but kfs than any ratio Motors '^ ''"■' '' 4^ ^^'^^ ^*^ defcribed in 12 feconds, 36 ftet greater than that of C to D, then A is to B as C to D. ■I will be delcribcd in 9 ftconds, i6 feet will be defcribcd Take the ftraight line a t g to reprefent the time of y in 4 feeonds, &c. Now H, y*, and '/, are fraiftions the body's motion along ACG, fo that the points a, c, of equal value, being equal to 4> or ^, that is, to the f, g, may rejirefcnt the inllants of tine in which the. velocity of 4 Itet per iccoiid. The value ot tin's frac- body paffes through the points A, C, F, G ; and the tion, or the quotient of tlie number of the units of portions e ordiuates are proportional to the •oelocities. Remark. The propriety or aptitude of exprefilng the time by the portions of the axis « eg, will, perhaps, appear more clearly in the following manner. Let a c g hi: any Itraight line, ami let i.< /■ ti he ano- ther line, ftraight or curved. Tct the itraight hr.e a b a, perpendicular to a g, be carried uniturmly down along this line, keeping always perpendicular to it, and there- fore always parallel to its firll pohtion a h x. In its various lituations e k %, e m z, &c. it will cut off areas a c k h, a e m h, &c. bounded by the axis by the ordi- uates a h and c t, or by the ordiuates a h aud e m, &c. and by the line h k g. By this motion the moveable or- dinate is faid, in the language of modern geometry, to generate the areas ackb, aemh, &c. At the fame time, let a point A move along the line ACG, fctting out from A at the inttant when the line a a fets out from a ; and let the motion of the point A be io re- gulated, that the fpaces AB, AC, AD, &c. generated by this motion, may increale at tlie fame rate with the areas, ab, ih, a e k h, a d I h, &c. or fuch that we (liall have AB to AC ^s a b i h, X. f n as we take the moments b c and f /fmaller. Therefore, in many cafes of praftice, where it may be eafy to meafure the ipaces defcribed in the different fmall moments of the motion, but difficult to afccrtain their illtimate ratio, fo as to obtain accurate meafures of the proportions of the velocities, we may reduce the errors of meafurement to fomething very in- fignificant, by taking thcle moments extremely imall ; and we ihall diminilh the error itlll more, by taking the proportion of the half fum of BC and CD to the half ium of EF and FG for the proportion of the velocities in C and F. It often happens that we have it not in our power to cotnpare the fpaces defcribed in fmall moments which are precifely equal. Still we can find the exait pro- portion of the velocities, if we can afcertain the ultinjate ratio of the increments of the ipaces, and the ultimate ratio of the moments of time in which thefe increments are defcribed : for it is plain, by conhdering the gradual approach of the points p and r to the points k and n, that the ratio of c k to f n is ftill the ultimate ratio of the bafes of redlangles equal to the mixtilineal areas, whether the altitudes (reprefenting the moments) are equal or not. Now the bafes of two reftanglcs are in the proportion of the reftangles directly, and of their altitudes inverfcly. But the ultiiuate ratio of the alti- tudes is the ultimate ratio of the moments, and the ul- timate ratio of the redangles is the ultimate ratio of the fpaces defcribed in thofe unequal moments. Therefore, in fuch cafes, we have. Cor. 2. The velocities arc in the ratio compounded of -j^ the dire£l ultimate ratio of the momentary increments of the fpaces, and the in-verfe ultimate ratio of the increments (or moments) of the times in which thefe increments of the fpa- ces are made. If J, V, and /, are taken to reprefent the magnitudes of the fpaces, velocities, and times, and if s, v, and f, arc taken always in the limiting or ultimate ratio of their momentary increments, we fhall have v always in the ratcil and RiUrUcJ Ml ti.11.5. D Y N A inverfcly. We exprefs this by the proportional equation v =^1., which or AcLvle- j^g 'proportiun of s direftly, and of/ is equivalent to the analogy V : ^■ zz — : — , or V : -u .... T t = Hi -.sT. * - 75. iV. £. Here obfcrve, that tliis is not the only way of flating the relation of fpace and time — the ablcilfa may be made the time, and the ordinate the ipaeej then the velocity ;=-^_. .V The couveif>- of tliis propoiition may be thus ex- prefied. I J the axis 3 g of ll-ie line li k o repreferU the lime of a •varied motion along the line AG, and ij the ordiiintes a h, b i, c k, lye. be as the •vel'tcilics in the injlanis a, b, c, or ill the points A, B, C ; then the areas a b i h, a c k h, ad 1 h, Sif. are proportimt.d t'j the fpiucs AB, AC, AD, This may be demonflrated in the fame way with the former ; but the indiredl demonftration is more brief, and equally ftiicl. If the fpaces AC, AF, &c. are not proportional to the areas ackh, afnb. Sec. they are proportional to forae other areas ackh', afri h', &c. which are bound- ed by the fame ordinatcs, and by another line h' k n'. But becaufe the areas a c k h', afn' h'. Sec. are always proportional to the fpaces AC, r\F, &c. defcribed on the line AG, the velocityin the point C is to tlie velo- city in the point F ;:s the ordinate c i is to the ordinate fri. Eut, by hypothefis, the velocity in C li to the velocity in F asii iofn, and fn' is equal to fn ; which IS abfurd. Therefore the fpaces AC, AF, are not pro- portional to any other areas, &c. Cor. The ultimate ratio of the momentary increments of the fpaces is compounded of the ratio of the velocities, and the ultimate ratio of the iniremenlj of the times : for when the moments ic, ef, are equal, it is evident thnt the ultimate ratio of the reflangles icp t, efr u is the fame with the ultimate ratio of the increments of the fpaces. But the ultimate ratio of thefe reftangles is the fame with their bafes c p and fr ; that is, the ratio of £ * to fn, that is, the ratio of the velocities. And when the moments are unequal, the ratio of the rcttanglcs is compounded of the ratio of their bafes and the ratio of their altitudes ; thnt is, compounded of the ratio of the velocities and the ultimate ratio of the moments of time. We have, therefore, S : j- ::^ VT : v I, and s = v I. It moll commonly happens, that we can only obfirve the accumulated rtfults of varied motions; and in them we only obferve a fpace paiild over, ami a certain por- tion of time that has clapfed during the motion. But being able to diftinguifn the portions of the whole fpace which are defcribed in known portions of the whole time, and having made fuch obfevvations in feveral parts of the motion, we difcover the general law that the mo- tion aifecls, and we affirm this law to hold univerfally, even though we have not obferved it in every point. We do this witli a degree of probability and confidence proportioned to the frequency of our obfervation. It is not till we have done this that we can make ufe of raici) and Ritarted Motinnm 78 M I C S. 527 the firft of thefe two propofitions, which enables us to Of Accck- afcertaln the velocity of the motion in its different mo- ments. Thus if we obferve, that a Hone in falling d« fcends one foot in the quarter uf a fecond, 16 feet in a . fecond, 64 feet in two feconds, and 144/eet in three fecoEids ; the general law immediately obferved is, " that the fpaces delcribed are as tlie fquarcs of the times ;" for I is to t6 as the fquare of -jth to the fquare of 1. Again, 16 is to 64 as 1' to 3' ; and 16 is to 144 as 1* to 3'. Hence we infer, willi great probability, tliat the (lone would fall 36 feet in a fecond and a half; for ''16 is to 36 as I' to i{-- ; and we conclude in the fame way for all other pans of the motion. Tliis immediate oljfervation of the analogy between A good ex- the fpaces and the fquares of the times fuggtfls an eafy^^P''"^ determination of the velocity in this particular kind ofjl'i^^^^'^'^*" motion; and it merits particular notice, being very often thod. referred to. V»'e<'antake a^to rcprcfent the time; and then, becaufe the areas which are to reprefent the fpaces defcribed mull be propoitioned to the fquarts of the portions of a^, we pciteive that the line which con^.es in place of h .i mull be a ftraight line drawn from a. For CNample, the ftraight line a S y. For this is'the only boundary which will give areas aba, ac y, aji, &c. proportional to a i\ a c', ad', &c. And we perceive that any ilraight line drawn from a will have this property. Having thus got our reprefentations of the times and the fpaces, we fay, on the authority of our theorem, that the velocity at the inftant b is to the velocity at the inllant d as b I' to d ^, &c. And now we begin to make inferences, purely geometrical, and exprefs our difcovery of the velocities in a very gi.ner.^1 and fimple manner. We rcmaric, that b (i is to ds as ab is to ad; and we make liie fame a31rmation concerning the ma'/-- nitudes reprcfented by thefe lines. We fay that the velocity at the inftant b is to the velocity at the inftant d as the time « i is to the time a d. AVc fay, in terms ftill more general, that the velocities are ])roportional to the times from the beginning of the motion. We more- over perceive, that the fp.ices are alfo proportional to the fquares of the acquired velocities ; or the velocities are as the fquare roots of the fpaces. We can farther infer, from the properties of the tri- angle, that the momentary increments of the fpaces are proportional to the momentary increments of the fquares of the times, or of the fquares of the velocities. We alfo obferve, that not only tlie vvhole acquired velocities are proportional to the whole elapfed times, but that the increments of the velocities are proper, tional to the times in which they are acquired ; for ^ " is to ;> •? as ^ i: to df. Sec. Equal increments of velocity are therefore acquired in equal times. Therefore fuch a motion may, in great propriety of language, be deno. , minated a uniformly accelerated motion; that is, a motion in ivhich we obferve the fpaces proportioned to the fquares of the times, is U motion uniformly accelerated ; and fpaces in the duplicate ratio of the times form the of. tenfible charaiSteriih'c of an uniformly accelerated motion. I^aflly, if we draw , x parallel to the axis a b, we per- ceive that the reilangle a ^ 1 x is double of the triangle /Iff. Now becaufe ae reprefents the time of the mo. tion, and « t reprefents the acquired velocity, the rec- tangle fl f 1 >. will reprefent the fpace which would be uniformly defcribed with the velocity << during the time 75' ■^28 of Ac.eV- riting- ard Retard! I g 1 O'CtS. D Y N A at. But tlie triangle «« I rcprtfcnts the fpace really defcribcd with the uniformly iicccleratcd motion tldring the Came time. Hence we inter, that the fpace that is defcribed in any tirni.', with a motion iiicrealing- uniform- Jy tVum nothing, i.i onc-lialf of the fpace wliicli would be uniformly defcribed duiiiig tlie fame time with the final velocity. Thefe are but a part of the inferences svhich we may draw from the geometrical properties of thofe reprelen- tat ions which we had fckdttJ of the diilerent meafure- able aSedions of motion. We may affirm, with refptft to the motions thcmfclves, ail the inferences which re- late to magnitude and proportion, and thus improve our knowledge of the motions. We took the opportunity of this very fimple and perfpicnous axample, to give our young readers a juft conception of the mathemnl'ical method of proiecuting iiRcharcical knowledge, and to make them fenfible ot the itnqueftionaWe authority for every theorem deduced in this manner. One of the moR important is, to difcover the accu- mulated refult of a motion of which we only cblerve the momentary increments. This is to be done by finding the area, or portions of the area, of the mixtilineal fpace tig oh ; and it is evidently anak'gous to the inveife me- .thod of fluxions, or the integral calculus. In moft cafes, we rauft avail ourfelves of the corolla- ry s = V i, and we obtain the folution of our queftion only in the cafes where our knowledge of the quanti- ties], t, and 11 (confidered as geometrical magnitudes, that is, as lines and furfaces), enables us to difcover s and >. Of Accelerating and Rethrdhig Forces. Having thus difcovered the proportions of the ve- locities in motions varying in any manner whatever, we can obfcrve the variations which happen in them. Thefe variations are the effefts, and the only marks and mea- fures, of the changing forces. They are the charafte- riftics of their kinds (confidered merely as moving for- ce?) ; that is, the indications of the direftions in which they act; for this is the only difference in kind of which they art fufceptible in this general point of view. If thtv increafe the velocity, their dircftion muft be con- ceived as the fame with that of the previous motion ; becaufc the refult of the adtion of a force is equivalent to the ci mpofition of the motion which that force would produce in a quiefcent body with the motion al- ready exifting : and an increafe of velocity is equivalent ■to the compofition of a motion in the fame direction. Havi g no other mark of the force but the accelera- tion, we have no other name for it in the abftraft doc- trines of dynamics, and we call it an acceleratikc FORCE. Had it retarded the motion, we fhould have called it a retarding force. In like manner, we have no meafure of the magnitude or inlenfity of an accelerating force, but the acceleration which "it prodr.ces. In order therefore to invelligate the powers which produce all the changes of motion, we mnlf endeavour to obtain mcafures of the acceleration. A continua. increafe of velocity is the effect of the continued aftion of accelerating forces. If equal in- crements of velocity jre produced in every fucceeding 8(jual moment of time, we cannot conceive that there is M I C S. any change in the accelcr-iting fore?. Therefore a u.ii- Of Actele. formly accelerated motion is the mark of the unvaried r*''"K »""1 adion of an accelerating force, that is, of the continued ';^"""'8 r c rr !/■• •• i'oices. action 01 a coi;ltant force ; or a force wnole inteniity •' ' ^ always the fame. When therefore we obicrvc a body ficfcribe fpacea proportional to the fquarea of the timr-^, we mull inter that it is urged forward by a forct: whole intenfity does not change ; and, on the other IrmJ, a conftant force mull produce a uniformly accelerated mo- tion by its continued aftion. And if any pitvljus cir. cumflances allure us of this continued aftlon of an in- vaiied force, we may make all the inferences which were mentioned under the article of uniformly accelerated mo- tion. 8t That foice muft furely be accounted double which ^I'^f"" of produces a double increment of velocity in the fame*"*''^ • 1 ■ T 1,- r 1 „• "nt force, time by its uniform action, we can form no ottier elu- mation of its magnitude. And, in general, accelerating forces muJJ be accDunted proportional to iht increments of •ue- locity ivhich they produce, by aSing uniformly during the fame or equal times. Suppofing tlura to aft on a body at reft. Then the velocity produced is itfclf the increment ; and we muft fay, that accelerbting forces are proportional to the ve- locities which they generate in a body in equal times. And becaule we found (n 79.), that the fpace dtfcri- bed with a uniformly accelerated motion is half the fpace which would be uniformly defcribed in the fame time with the final velocity, which fpace is the direft meafure ot this velocity, and becaule halves have the fame proportion with the wholes — we may fay that ateeleratiiig forces are proportional to the fpaces lhrough-'^"°y^^ which they impel a body from refl in equal times by their '^ " ' tin form aSicm. Ttiis is an important remark ; becaufe it gives us an eafy meafure of the force, without the trouble of firft computing the velocities. It alio gives us the only dif- tinft notion that we have of the rocafurement of forces by the motions which they produce. When fpeakiug of the compofition ot forces we dillinguilhed or deno- minated ttiem by the fides and diagonal of a paraltelo- gram Thefe lines mult be conceived as proportional to the fpaces through which the forces urge the body uni- formly during the fmall and infenlible time of their ac- tion, which time is fuppofed to be the lame for both forces ; for the fides of the parallelogram are fuppofed to be feparately defcribed in equal times, and therefore to be proportional to the velocities generated by the conftituent forces. If indeed the forces do not aft uni- formly, nor fimiiarly, nor during equal times, we can- not lay (without farther inveftigation) what Is the pro- portion of the intenfity of the forces, nor can we infer the compofition of their a£lion. We mull at leaft fup- pofe, that in every inftant of this very Imall time of their joint aftion, their direftion remains unchanged, and tiiat their intenfities are in the fame ratio. We ihaLl fee by and bye, that with thefe conditions the fides of the parallelogram are ftiU proportional to the velocities ge- nerated. In the mean time, we may take the fpaces througti which a body is uniformly impelled from reft (that is, with a uniformly accelerated motion) as the meafures of the forces ; yet thefe fpaces are but th» halves of the me.ifures of the velocities. Then, if a bo- dy be moving with the velocity of 52 feet per fecond, and an accelerating force afts on it during a fecond, and D Y N A if Acfele- and if this force be fuch that It would impel the body •Qiing.ind ^from a tlate of rcll) l6 feet, it will add to the body a ietardmg velocity of 32 feet per fecond. Accordingly, this is _ the efteft of gravity — the weight of a pound of lead may be confidered as a force which does not vary in its in- tenlity. We know that it will caufe the lead to fall 16 fee: in a fecond ; but if the body has already fallen 16 feet, we know that it is then moving with the velocity of 32 feet per fecond. And the faft is, that it will fall 48 feet farther. in the next fecond, and will have acq\ii- rcd the velocity of 64 feet per fecond. It has there- fore received an augmentation of 3.1 feet of velocity by the adlion of gravity during the 2d fecond ; and gravi- ty is in fa£l a conltant force, caufing equal increments of velocity in equal times, however great the velocities may be. ^ It does not atl like a llream of fluid, whofe impulfe or aftiun diminilhes as the folid body withdraws from it by yielding. But fuppofing that we have not compared the incre- ments of velocity uniformly accjuired during equal times, in what manner fliall we meafure the accelerating forces ? In fuch a cale, that force muft be accounted double which generates the fame velocity, by afting uniformly during half the time ; for when the force is fuppofed invariable, the changes of velocity which it produces are proportional to the times of its aflion ; therefore if it produces an equal velocity in half the time, it will produce a double velocity in an equal time, and is therefore a double force. The fame may be faid of every proportion ot time in which an equal change of velocity is produced by the uniform aftion of an accelerating force. The force muft be accounted greater in the fame proportion that the time required for the produAion of a given velocity in a body is Icfs. Hence we infer, that accelerating forces are iti'verfely pro- portional to the limes in iv/jic/j a given change of •velocity is produced by their uniform aBion. By combining thefe two propofitions we eftablifh this g general theorem : ileafure ol^^'^'^^'i'^l'^g f"'''^^^ '"'^ proportional to the changes of ve- ccelera- locily ivhich they produce in a body by their uniform aBion dircdly, and to the times in •which thefe changes are produced inverfely. If, therefore, A and a are the forces, V and 1/ the changes of velocity, and T' and /' the portions of time in which they are uniformly produced, we iiave V' 11' A:a = \-'t':-o'r, = Y':T ■u' And a = -r- ing force, The formula a I' is not reftrlfted to any parti- cular magnitude of 1/ and /'. It is true, therefore, when the portion of time is dimlniflied with(*it end ; . for flnce the adtion is fuppofed unifdrm, the increment of velocity is leffened in the fame proportion, and the value of the frafkion -;- remains the fame. The cha- raflers or fymbols v' and /' are commonly ufed to ex- prefs jfn/Vf portions of -u and /. The fymbols v and t are ufed by Newton to exprefs the fame things taken in the ultimate or limiting ratio. They are ufually confi- dered as inde/inilely fmall portions of v and t. We fhall abide by the formula a = -r' ■ t SuFfL. Vol. I. Fart II. M I C S. ' 52(; It muft always be kept in mind, that v and / arc ab- Of Acccle- ftrail numbers ; and that v refers to fome unit of fpace, f '"ng jnd fuch as a foot, an inch, a yard ; and that / refers to i^orce- fome unit of time, fuch as an hour, a minute, a fecond ; r au(l ef[)ccially that a is the number of the fame units 8j of fpa.-e, whicli will be unifurmly defcribcd in one unit'*""*''* of the time with the velocity generated, by the force],;.* "'^""* adliiig uniformly during that unit. It is twice the fpace adually defcribcd by the body during that unit when impelled from reft by the accelerating force. It is neceffary to keep hold of thefe clear ideas of the quantities expreffed by tlie fymbols. On the other hand, when the meaUire of the accelera- Metfure of ting force is previoufly known, we employ the theorem' '■^'■'/^K'^ "^ a t' =1 v ; that is, the addition made to the velocity*" '"^"^' during the whole, or any part, of the time of the action of the force is obtained by multiplying the acceleration of one unit of lime by the number of fuch units con- tained in /'. Thefe are evidently leading theorems in dynamics ;'riif''eraea. becaufe all the mechauical powers of nature come un- ^^^'^*' der the predicament of accelerating or retarding forces. '.^.,'u,(j It is the coUeftion of thefe in any fubjcil, and the man- pan of our ner in which they accomjjany, or are inhereiU in it, knowledge which determine the mechanical charafter of that fub-°'. '''''^'^^''''- jeft ; and therefore the phenomena by which they arCj,.^^ brought into view are the the charafteriltic phenomena. Nay, it may even be queftioned, whether the phenome- na bring any thing more into view. This force, of which we fpeak fo familiarly, is no objedl of diftinft contem- plation ; it is merely a fomething that is proportional to — And when we obferve, that the — , found in the motions that refult from the vicinity of a body A, is double of the J^, which refults from the vicinity of t another body B ; we fay that a force refides in A, and that it is double of the force refiding in B. The ac- celerations are the things immediately and truly ex- prefted by thefe fymbols. And the whole fcience of dynaniics may be completely taught without once em- ploying the word force, or the conception which we imagine that we form of it. It is of no ufe till we come to lludy the mechanical hiftory of bodies. Then, in- deed, we muft have fome way of exprelCng the fact, thai . ji feet an acceleration = -^ ; — is obferved in every thing on the furface of this globe ; and that an acceleration := 4! 8 feet , V' is obferved over all the furface of the fun. Thefe fafts are charafteriftic of tliis earth and of the fuu ; and we exprefs them ihortly by faying, that fuch and fuch forces rcfide in the earth and in the fun. It will pre- ferve us from many millakes and puzz-ling doubts, if we reiolutely adhere to this meaning of the tevm force; and this will carry mathematical evidence through the whole of our inveiligations. s^ As velocity is not an immediate obiedl of contem-Ai otiier plation, and all that we obferve of motion is a fpace'"' futeof and a time, it may be proper to give an cxprellior 01, . this meafure of accelerating force which involves no other idea. Suppofing the body to have been previ- oufly at reft, we have a = — . Multiply both parts cce era- ; force 3X of 53^ D Y N A of accelera- ting force. Of Acce'.c-of the fradioi) by t, which does not change its value, rating and ^ ^ Retarding and we have J = — . But v t zz s ; and therefore a Farces. • i The formula a = -j is equivalent to the proportion /» : I = s : a ; and a would then be t}>e fpace through which the accelerating force would impel the body in one unit of the time /. But this is only half of the meafure of the velocity which the accelerating force ge- nerates during that unit of time. For this reafon we did not exprefs the acccleraring force by an ordinary equation, but ufed the fymbol ==. In this cafe, there- fore, of uniform adlion, we may exprefs the accelera- 2 J- , ting force by a zz —r- The fcllovi'ing theorem is of (lill more extenfive ufe gr in all dynamical difqiiilitions. Mod Kent- ylccelerating forces are proportional to the momentary in- ral meafure cremeuts of the fquares of the velocities direPdy, and as the fpaees along ijhich they are uniformly acquired in- •verjely. Let AB, A'C, and AD (fig. 14.), be three lines, defcribed in the fame or equal times by the uniform ac- tion of acceleratirtg forces ; the motions along thefe lines will be uniformly accelerated, and the lines them- felves will be proportional to the forces, and may be employed as their meafurcs. On the greateft of them AD, defcribe the femicircle ABCD, and apply the other two lines A'B, A'C as chords AB, AC. Draw EB, FC perpendicular to AD. Take any fmall por- tions B i, C f of AB and AC, and draw i e, cf per- pendicular to AD, and E h and F i parallel to AB and AC. Then, becaufe the trian<(les DAB and BAE are fi- milar, we have AD : AE'= AD" : AB'. And be- caufe AD is to A B as the velocity generated at D is to the velocity generated at B (the times being equal), we have AD to AE as the fquare of the velocity at D to the fquare of the velocity at B ; which we may exprefs thus : AD: AE = V", D : V", B. For the fame reafons we liave alfo AD : AF = V, D : V% C. Therefore AE : AF = VS B : V% C. But becaufe in any uniformly accelerated motion, the fpaees are as the fquai-es of the acquired velocities, we have alfo AE: Ae = VSB : V i, and AF : A/ = V, C : V c. Therefore E e is to F/as the increment of the fquare of the velocity acquired in the motion along B i to the increment of the fquare of the velocity acquired along C c. But, by fimilarity of the triangles ABD and 'E e h, we have AB : AD = E 1; : E A ; and, in like manner, AD : AC zz Yi :¥f. Therefore AB : AC = E^ X Fi : F/X E/j. Now AB and AC are proportional to tfie forces which accelerate tfie body along the lines A'B and A'C ; E e and F/ are proportional to the increments of the fquares of the velocities acquired in the motions M 1 C S. along the portions B I and C c ; and E h and F i are Of Accde. equal to thofe portions refpedlively. The ratio of AB '■"tini? and to AC is compounded of the dirett ratio of E «• to F/; "p^"'','''^- and the inverfe ratio of JL h to T i. The proportion . , ' t 1 is therefore demonftrated. The proportion may be cxprefTed thus : Ee Ff . ; AB : AC =. p-T : y-,, and may be exprcflcd by the proportional equation AB = ^y or, fymbolieal- Remark. Becaufe the motion along any of thefe ^.l- is but three hncs is uniformly accelerated, the relation between one-half fpaees, times, and velocities, may be reprefentcd by' "'"* means of the triangle ABC (fig. 15.) ; where AB re-of.^,! prefents the time, BC the velocity, and ABC the fpace. If BC be taken equal to AB, the triangle is half of the fquare ABCF of the velocity BC ; and the triangle ADE is half of the fquare ADEG of the velocity DE. Let D ^ — j-^ r ; keeping always in mind, that a, V, and v, relate to the fame units of time and fpace, and that a is that number of units of the fcale on which S and s are meafured, which is run over in one unit of time. This will be more clearly conceived by taking an Meafmc of example. Let us afcertain the acceleratl-e power ofg'^X'''' gravity, fuppofinpf it to adt uniformly on a body. Let*^""' "^ P, r ' , r > • r 1 L ■ ■ r , as an acce- the fpaees be meafured in feet and ttie time in feconds. i.-rming It is a matter of obfervation, that when a body has fal- force. Icn 64 feet, it has acquired a velocity of 64 feet per fecond : and that when it has fallen 144 feet, it has ac- quired the velocity of 96 feet per fecond. We want to determine what velocity gravity communicated to it by afting on it during one fecond. We have V =: 9216, and ■zjJ = 4096 ; and therefore V" — ©•» = 5120. S = 144, and s = 64, and S — s zz 80, and 2 (S — s) 5120 = 160. Now a = ~TKa> ^2'^- Therefore gravi- ty D Y N A jf Aceele- ty has generated the velocity 32 feet per fecond by rating an i j£^;„g unifonnly during one fccoiid. The nugmrntdlion of the fquure of the wfncity is pro- pm-tional to the force and to the fpace jointly. I'or, bccaiilc Uelariliiig Forces. 8b. — -: — , we have a s :=. vv. Theorems refpeiJliiii; relauliijg forces Thus we learn, that a given force ailing uniformly on a bodv along a given fpace, produees the fame in- crement of the fquare of the velocitVi whatever the pre- vious velocity may have been. Alfo, in the fame man- ner as we formerly found that the augmentation of the velocity was proportioned to the time during which the force has acted, fo the augmentation of the fquare of the velocity is proportional to the fpace along which it h the body in which it is fupijofcd to refide. Acceleration expreffes fome rdatioii of the vcl'icity and time. This relation may be geometrically exprcf- fed in a variety of ways. In figure 13. the uniform acceleration or the unvaried relation between the velo- city and the time is very aptly expreffcd by the con- flant ratio of the ordinates and abfciffes of the triangle rt ? ». The ratio to f s ; but, for limilar reafons, it is in a lefs ratio than that oi c q tofr; and therefore (as in the other pro]>ofition) the force at the inftant c is to the force at the inrtant/as c k tofn. Cor. Becaufe c p is to f s in the ratio compounded 9'> of the direft ratio of the reftangle c p t b to the reA- angley J x g, and the inverfe ratio of the altitude b c to the altitude fg ; and becaufe thefe reftanglcs are pro- portional to the increments of velocity, and the ulti- mate ratio of the altitudes is the ultimate ratio of the mo- ments or increments of the time — we mutl fay, that tic accelerating forces (that is, their inteti/ities or prejjiires producing acceleration) are dircSly as the incrtmenis of -velocity, and inverfely as the increments of the times : Which propofition may be exprefted, in regard to two accelerations A and a, by this analogy ; V V A:.■ ■ n i 1 ci' c 1 • beproducel^"'-''^^^'^ m an inltant by the aition ot an accelerating inaninftantforce. When the fig. 13. is ufed for the Icale of acce- by any ic- lerations, and they aire reprefented by the ordinates of celera Jig ^^ y^^^ j^ j, ^^ ^-^^ Increment of velocity is reptcfented 93 All thefe theorems relate to cbanraw GK perpendicular to DH. Then, if we fuppofe that the force a6ts with the unvaried in- tenlity CG through the whole fpace CD, the reftangle CDKG will exprels half of the increment of the iquare of the velocity (n° 85 ). We may fuppofe that the force afts uniformly along the adjoining fmall fpace Dr with the intenfity DH. The reftangle DH r will in like manner exprefs another half increment of the fquare of the velocity. And in like manner v/c may obtain a fuccefiion of fuch increments. The ag- gregate or fum of them all will be half the difference between the fquare of the velocity at B and the fquare of the velocity at E. If we employ f to exprefs the indetermlned or va- riable intenfity of the accelerating force, and i> to ex- prefs the variable velocity, and ■» its increment uniform- ly acquired ; then the reftangle CDKG will be ex- prefTed by f s'. We have feen that this is equal to ■v-J. Therefore, in every cafe where we can tell the aggre- gate of all the quantitiesy J, it is plain that we will ob- tain half the diflerence between the fquares of the ve- locities in B and E, on the fuppofition that the intenfi- ty of the force was conftant along each little fpace, and varied Of Aceele raiirj; and Retarding Forces. . 5* More con* venient manner of confiderirg the a(51ion of force?, and more Irtciueiiily con'ing in«- to view. l'3f Accele- ra'ini; and Retariling forces. 95 Mnft im- portanc theorem / Keiutons I. 39-) 9«. C«nverfe. D Y N A varied by ftarts. Then, by iiicreafing the number, and (limi'iilhiiig the magnitude, of thofe little portions of tiie fpace without end, it is evident that we terminate in the eMprcffion of the real ftate of the cafe, i. e. of a force varying conlinually ; and that in this cafe the ag- gregate of thefe rciJtangles occupies the whole area AEIF, and is equivalent to the fluent of/ J, or to the fynibol Ifs, ufed by the foreign mathematicians to ex- prefs this fluent, whicli they indeed conceive as an ag- gregate of fnia'.l reftangles f s. And we fee that this area expreflTes half of the augmentation of the fquare of the velocity. Therefore, If the abfciffa AE (fig. l6. ) of a line FGl is the path along "which a body is urged ly any accelerating force, and if the ordinates BF, CG, DH, i^c. are proportional to the forces a&ing on the points B, C, 1), He. the intercepted aieas BCGF, BEIF, i^c. are proportional to the augmen- tations of the fquare of the •ve'ocity. Obferve that the areas BCGF and DEIH are alfo proportional to the augmentations made on the fquares of the velocities in B and D. Obferve alfo, that it is indifferent what may have been the original velocity. The aftion of the forces re- prefented by the ordinates make always the fame addi- tion to its fquare ; and this addition is half the fquare ot the velocity which thole forces would generate in the body by impelling it from relt in the point A. Lailly, on this head, obferve, that we can ftate what conllant or variable force will make the fame augmen- tation of the fquare of the velocity by impelling the body uniformly along the fame fpace BE ; or along what fpace a given force mutt impel the body, in order to produce the fame increafe of the fquare of its velo- city. In the firft cafe, we have only to make a rect- angle BEN f, equal to the area BEIF, and then B f is the intenfity of the conftant force wanted. In the fe- cond cafe, in which the force EO is given, we muil make the rectangle A= is to the area BEN »- as the fquare of the velocity at D to the fqu;ire of the velocity at E. Thefe areas, hnving equal bales ■ DH and EN, are as their altitudes BD and BE ; that is, the fpaces defcribed are as the fquares of the ac- quired velocities. And we fee that this charaiteriftic mark of uniformly accelerated motion is included in this general propofition. ,^, . 2. Let us fuppofe that the body is impelled from A Hx.uiiple" (fig. 17.) towards the point C, by a fTirce proportional '^'•''^""'' "^ to its diftanee from that point. This force may be re- ~" prefentcd by the ordinates T).\, EB, e b, &c. to the a ftraight line DC. We may take any magnitude of thefe ordinates; that is, the line DC may make anv angle with AC. It will fimplify the inveftigation if we make the firft force AD^^AC. About C defcribe the circle AH n, cutting the ordinate EB in F; let f i be auothev ordiaute, catting the circk in/ very near ■ culiar '"ni rrt. ancc. . SU D Y N A Of Accele to V ; draw CH perpendicular to AC, and make the rati.ii; and g^^.^ ^ A - fF, and draw he parallel to HC ; join Force"^ FC and DH, and draw F^ perpendicular to/A. Let * IML be another ordinate. The area DADE is to the area DAKL as the fqnare of the velocity at B to the fquare of the velocity at K. But DABE is the exccfs of the triangle ADC above the triangle EBC, or it is half of the exccfs of the fqiiare of CA or CF above the fquare of CB, that is, half the fqnnie of BF. In like manner, the area DAKL is equal to half the fquare of KM ; but halves have the fame ratio as the integers ; therefoie the fquare of BF is to the fquare of KM as the fquare of the velocity at B to the fquare of the velocity at K ; therefore the ve- locity at B is to the velocity at K as BF is to KM. The velocities are proportional to the fines of the arches of the quadrant AFH defcribed on AC. Cor. I. The final velocity with which the body ar- rives at C, is to the velocity in any other point B as radius to the fine of the arch AF. Cor. 2." The final velocity is to the velocity which ■ the body would acquire by the uniform action of the initial force at A as « to \^2 ; for the reftaugle DA CH exprefTcs the fquare of the velocity acquired by the uniform aflion of the lorce DA ; and this is double of the triangle DaC ; therefore ihe fquares of thele velocities are as i and 2, and the velocities are as ^i and i/2, or as i to i/z. C r. 3. The time of defcribing AB is to the time of defcribing AC as the arch AF to the quadrant AFH. 101. For when the arch F/ is dirainilhed continually, it is plain that the triangle fi F is ultimately fimilar to CFB, by reafon of the equal angles Cii (or CFB) and fi F, and the right angles CBF and/F; ; there- fore the triangles/;- F and CBF are alfo fimilar. More- over, B i is equal to Y g, F/is equal to h H, which is ultimately equal to f C ; therefore fince the triangles J'gF and CFB are fimuar, we have F^ : F/=: FB : FC, •= FB : HC ; therefore B i is to f C as FB to HC, that is, as the velocity at B to the velocity at C; therefore B b and c C are defcribed in equal moments when indefinitely fmall ; therefore equal portions F/, /} H, of the quadrant correfpond to equal moments of the accelerated motion, along the radius AC ; and the aiches AF, FM, MH, Sec. are proportional to the times of defcribing AB, BK, KC, &c. Cor. 4. The time of defcribing AC with the une- oially accelerated motion, is to the time of defcribing it uniformly with the final velocity as the quadrantal arch is to the radius of a circle ; for if a point n~.ove in the quadrantal arch fo as to be in F, /, M, H, &c. when the body is in B, b, K, C, it will be moving uniformly, becaufe the arches are proportional to the times of dtfcribing thole portions of AC ; and it will be moving with the velocity with which the body arrives at C, becaufe the arch /} H is ultimately =: C c . Now if two bodies move uniformly with this velocity, one in the arch AFH, and the otlier in the radius AC, the times will be proportional to the fpaces uniformly de- fcribed ; but the time of defcribing AFH is equal to the time of the accelerated motion along AC ; therefore the propofition is manifeft. Cor. J. If the body proceed in the line C a, and be retarded in the fame manner that it was accelerated M I C S. I along AC, the time of defcribing AC unJfonnly with Of Aet«, the velocity which it acquires in C is to the time of *■"''"?" - - - . . T °eurdii Forces defcribing AC a with the varied motion, as the diame- ^"*"'" «03. ter of a circle to the circumference ; for becaufe thei, momentary retardations at K', B', &c. are equal to the accelerations at K and B, &c. the time of defcribing AC a is the fame with that of defcribing AH a uni- formly with the greateft velocity. That is, to the time of defcribing AC uniformly as AH a to AC, or as the circumference of a circle to the diameter. There- fore, &c. N. B, In this cafe of retarding forces it Is convenient to reprefent them by ordinates K'L, BE, a D', lying on the other fide of the axis AC a ; and to confider the areas bounded by thefe ordinates as fub- traftive from the others. Thus the fquare of the velo- city at K' is expreffed by the whole area DACK'L'D, ihe part C'K'L being negative in refptft of the point DAC. This obiervation is general (See alfo Optics, n" 125, Etirycl.) Cor. 6. The time of moving along KC, the half of AC, by the uniform aflion of the force at A, is to that of defcribing AC ti by the varied atlion of the force directed to C, and proportional to the diltance from it, as the diameter of a circle to the circumference; for when the body is uniformly impelled along KC by the conltant force IK, the Iquare of the velocity acquired at C is reprefented by half the rcftangle IKCH, ami therefore it is equal to the velocity which the variable force generates by impelling it along AC (bv the way, an important obiervation). The body will defcribe AC uniformly with this velocity in the fame time tiiat it is uniformly accelerated along KC. Therefore by Cor, 5. the propofition is manifeil. Cor, 7. if two bodies defcribe AC and KC by the action of forces which are every where proportional to the diltanccs from C, tiieir final velocities will be pro- portional to the dillances run over, and the times will be equal. For the fquares of the final velocities are proportional to the triangles ADC, LKC, that is, to ACs KCs and therefore the velocities are as AC, KC. The times of defcribing AC and KC uniformly, with velocities proportional to AC and KC, muil be equal ; and thefc times are in the fame ratio [viz. that of radius to 3th of the circumference) to the times of delcribing AC and KC with the accelerated motion. Therefore, &c. Thus, by availing ourfelves of the properties of the circle, v^'e have dilcovered all the prc-perties or charac- ters of a motion produced by a force always dirt died to a fixed point, and proportional to the diltance from'it. Some of thcfe are remarkable, luch as the lail corol- lary ; and they are all important ; for there are innume- rable cafes where this law of aftion obtains in Nature. It is nearly the law of aftion of a bow ftiing, and of all elaftic bodies, when their change of figure duriiig their mutual aftion is moderate ; and it has been by the help of this propofition, firit demonilrated in a particular cafe by Lord Brouncker and Mr Huyghens, that we have been able to obtain precife meatures of time, and confequently of aftual motions, and confequently of any of the mechanical powers of Nature. It is for this rea- fon, as well as for the eafy and perfpicuous employment of the mathematical method of proceeding, that we have felefted it. Initead of giving aoy more particular cafes, we may obferve pro DYNAMICS. S35 made on the fquare of tlic velocity of both bodies. Of Accele- portional to any power whole index is n — I of the Therefore, if V and U are the velocities before colIihi;i], fafng and " • ■■ ' • and -u and B the velocities after colh'lioii, of the two bo- HWt,"'.^ i Of Accele- obferve in general, that if the intenfity of the force be lU'ar.iiMg jiin;,„^.g^ a„j [( ^ be the diftance from the fixed point i_ , at which the body begins to be accelerated, and x its diftance from that point in any part of the motion, the velocity will be =f \^a" — \". This is very plain, be- caiife the increment CGHD of the area of fig. 1 6. which is alfo the increment of the fqnare of the veloci- ty, is == .■e''~'.v, and the area is = .v" ; and the whole area, corvcfponding to the diltancc a, is a". Therefore the portion of the area lying beyond the diftance .v is ./" — .\". Tiiis is as the fquare of the velocity, and therefore tiie velocity is as the iqiiare root V^a" — a" of this quantity. burcee. Thi:> propolitiim, J" s == vi', or _/" == — r". the 39tli of the tirft book of Newton's Principia, and is perhips the moll important in the whole doftrioe of dy- namics, whether employed for the inveftigation ot forces or for the explanation of motions. It funiilhes the moft immediate data for both purpofes, but more efpe- cially for the laft. By its help .Sir Ifaac Newton w.is able to point out the numerous dlllurbances of the pla- netary motions, and to feparate them from each other ; thus unravelling, as it were, that moft intricate motion in which all are blended together. He has given a moft wondertul fpecimen of its application in his Lunar Theory. We now are able to explain all the puzzling fafls which were adduced by Leibnitz, and his partiians in fupport of their mcafure of the forces of bodies in mo- tion. We fee why four fpriiigs, equally bent, commu- nicate but a double velocity, and nine fprings but a triple velocity ; why a bullet moving twice as faft will penetrate an earthen rampart to a quadruple depth, &;c. &c. This theorem alfo gives a moft perjpicuous explanation of the famous doftrlne called confervatio virium •vivarum. V/hen perfectly elaftic bodies att on each other, it is found that the Inm of the malTcs multiplied by the fquares of the velocities is always the fame. This has been inbftituted, with great encomiums, by the German philofophers in place of Des Cartes's principle, that the quantity of motion in the univerfe, eftimated in one di- veftion, remains always the fame. They are obliged, however, to acknowledge, that in the ailions of perfedl- ly hard bodies, there is always a iofs of -vis viva, and therefore have denied the exiftence of fuch bodies But there is the fame Iofs in the mutual anions of all loft or duftile, or even imperfeftly ilallic, bodies ; and they are miferably puzzled how to explain the faft ; but both the confirvatio and the am'tjfio are neceflary confe- quences of this theorem. In the collifion of elaltic bodier, the whole change of motion is produced during the fliort time that the bo- dies are comprefled, and while they regain their figure. When this is completed, the bodies are at the fame dif- tance from each other as when the mutual aftion be- gan. Therefore the preceding body has been accelera- ted, and the following body has been retarded, along equal fpaces ; and in every point of this fpace the acce- lerating and the retarding force has been equal. Con- fequently the fame area of fig. 17. expreffcs the change dies A and B, we nuift have AxV'— 1;= = Bx«' V', and therefore A X V -|. B X U' ::: A X i;' -f B X u^ But in the other clals of bodies, which do not com- pletely legaln tiieir tignre, but remain ccmprefled, they are nearer to each other when their nmtu.d adion is ended than when it began. The foremoft body has been accelerated along a fliorter Ipacc than that along which the other has bten retarded. The mutual forces have, in every inftant, been equal and oppoiite. There- fore the area which expreflcs the diminution of the fquare of the velocity, muft exceed the area exprefling the augmentation by a quantity that is always the fame when the permanent compreffion is the fame ; that is, when the relative motion is the fame. A X V' — li' muft exceed B X «■— Us and A X V 4- B X U' muft exceed A X -y -f B X B=. This fame theorem is of the moft extenfive ufe in all pradical queftions in mechanic arts; and without it mechanics can go no farther than the mere ilatement of equilibrium. Hermann, profeffi.r of mathematics at Pavla, one of '"'''^o'T of the ornaments of the mathematical clafs of philofophers, "" ?^' " has given a pretty demonftration of this valuable propo- fition in the Acia ErudUorum Lipfia for 1709; and fays, that having fearched the writings of the mathema- ticians with great care, he found himftlf warranted to fay, that Newton w.is the undoubted author, and boalla- of his own as the firft fynthctical demonftration. The purpofe of this aftcrtion was not very apparent at the time ; but long after, in 1746, when Hermann's papers, preferved in the town-houfe of Pavia, were examined, in order to determine a difpute between Maupertuls and Koenig about the claim to the difcovery oi the principle of haft aSlion, letters of Leibnitz's were found, requell- ing Hermann to fearch for any traces of this prupofi- tion in the writings of the mathematicians of Europe. Leibnitz was by this time the envious detradtor from Newton's i-cpiitation ; and could not but p-.-rccive, that all his contorted arguments for his doftrine received a clear explanation by means of this propolition, in per- feft conformity to the ufual meafure of moving forces. Newton h.id difcovered this theorem long befire the p;iblication of the Principia, and even before the difco- very of the chief propolition of that book in 1666; for in his Optical Lcftures, the materials of which were in his polfelfion in i66.|, he makes frequent life of a propofition founded on this (fee n" 42.) We may here remark, that Hermann's demonftration is, in every ftep, the fame with Dr Barrow's demonftration of it as a theorem merely geometrical, without fpeaklng of mo- ving forces (fee LsS. Geomdr. xi. p. 85. edit. 16 ), but giving it as an inftance of tlie transformation of curves, which he calls scales of velocity, of time, of acceleration, &c. It is very true that Barrow, in thefe mathematical lectures, approached very near to both of Newton's difcoveries, the fluxionary geometry, and the principles of dynamics ; and the junto on the continent, who were his continual detraftors, charge him with im- pudent plagiarifm from Dr Barrow, and even fay that he has added nothing to the difcoveries of his teacher. But furely Dr Barrow was the beft judge of this mat- ters. 104 Sin liar in |}an[s and jMiints, what ? 536 D Y N A of At«!t. tcr ; and fo far from rcfentinp; ihe ufe which Newton satir.g aiij ^^^^ made of what he had taught him, he was charmed Ketsriluig -i, • ri • ■ /■ r, ■ /r i-r.i Forces. W'ltn the genius iil the juvaus ipeaatijjwms his Icholar, w— y— and of his own accord gave hiin his profefTorial chair, and ever after h'vcd in the iitmoft. harmony and friend- fhip with him. Nay, it would even appear, from feme exprcflions in fhofe very Icflurcs, that Dr Barrow owed to young Newton the full thought of making fuch cx- teiiiive ufe of motion in geometry. We recommend this work of Barrow's to the ferious perufal of our readers, who willi to acquire clear notions of the Icience of mo- tion, and an elegant tafle in their mechanical difquifi- tions. After all the cultivation of this fcience by the commentators and followers of Newton, after the Pho- rottoniui of Hermann, the Mcchiwica of Euler, the Dy- naniique of D'Alenibert, and the l\Jechaniqtie Analytique of De la Grange, which are undoubtedly works of tran- fcendent merit and utility, the /'rmr/fia of Newton will ftill remain the mofl pleafing, perfpicuous, and elegant fjjccimen of the application of mathematics to the fcience of uiiiverfiil mechanics, or what we call Dynamics. TI»e two fundamental theorems f t := v, and f 1 := 1)11, enable us to folve every queftion of motion ac- cilerated or retarded by the aftion of the mechanical " powers of nature. But the employment of them may be greatly expedited and fimplified by noticing two or thrte general cales which occur very frequently. Thcfe may be ec.UeJfimilar injlants of time, and Jimilar points oj Jpace •which divide gii}cn porlions of time, and of [pace in the fame ratio. Thus the nu'ddle is a iimilar iii- ftant of an hour or of a day, and is the fipiilarly fituated point of a foot or of a yard. The beginning of the 2ift minute, and of the 9th hour, are fimilar inflants of an hour and of a day. The beginning of the 5th inch, and of the 2d foot, are fimilar points of a foot and of a yard Forces may be faid to aB Jimilarly luhen their ititen- tion5,what?^/(Vj. in Jimilar isjiants of time, or in Jimilar points of fpace, are in a conflant ratio. Thus in fig. 17. when one body is impelled towards C from A, and another from K, each with a force proportional to the diftance of every point of its motion from C, thcfe forces may be faid to adl funilarly along the fpaces AC and KC, or during the times reprefented by the quadrantal arches AJ?H, KNO. The following propofitions on fimilar aftioiis will be found very nfeful on many occafions ; but we muft premife a geometrical lemma. If there be two lines EFGl I (fig. 18.), e f g h, fo re- lated to their abfciffes AD, a d, that the ordinates IK, ili, drawn from fimilar points I and i of the abfciffes, are in the conilant ratio of AEtoaf; then the area ADHE is to the area a d h e as the reftangle of AD X AE to the reftangle a d X a e. For let each abfciffa be divfded into the fame number of equal and very fmall parts, of which let CD and c d be one in each. Infcribe the rectangles CGID, c g i d. Then becaufe the number of parts in each axis is the fame, the lengths of the portions CD and c d will be proportional to the whole abfciffes AD and a d. And becaufe C and c are iimilar points CG is to r^f as AE is to a e. Therefore CD X. CG : c d y. c g = AD AE : a d y. a e This is true of each pair of corre- fponding reftangles ; and therefore it is true of their Aims. But when the number of thefe reflangles is in- lot. Similar ao Io5. M I C S. creafed, and their breadth dimiuiflied without end, it JjOf .Afcele. evident that the ultimate ratio of the fum of all the rift- "''"« »»'! angles, fuch as CDHG to tlie fum of all the rcftangles "n,ces^ e d h g, h the fame with that of the area A DUE to tlia ^_-y.^| area a d h e, and the propofition is manifcA. If two particles of matter are fmilarly impelled during I07 given limes, the changes of 'ociccily are as the times and as the forces jointly. Let the times be reprefented by the flraight lines ABC (fig. !().) and c2 i c, and the forces by the ordi- nates AD. BE, CF, and a d, b e, c f. Then if B and b arc fimilar inftants (fuppofe the middles) of the whole times, we have BE : b e z=: AD : a d. There- fore, by the lemma, the area ACDF is to a c f d at AC X AD to a c y ad. But thefe areas are propor- tional to the velocities (no ^2), and the piopofitioii ig demonflratcd. For the fame reafon the change of ve- locity during the time AB is to the change during ai as AB X AD to a b X a d. Cor. I. If the ti.nes and forces are reciprocally pro- portional, the changes of velocity are equal ; and if the forces are fnverfely as the times, the changes of velocity are equal. If two particles be Jimilarly urged along given fpaces, the changes made on the fquares of the velocities are as ihe forces and fpnces jointly. For if .AC (fig. 19.) and a c are the fpaces along which. the particles are impelled, and the forces are as the ordinates AU and a d, the areas ACFD and acfd are as the changes on the fquares of the velocities. But thefe areas are as AC X AD, and ac X ad. There- fore, Sic. Cor. 2. If the fpaces are inverfcly as the forces, the changes of the fquares of the velocities are equal ; and if thefe are equal, the fpace- arc inverfely as the forces. Cor. 3. If the fpaces, along which the particles have been impelled from a previous flcite of refl, are direfily as the forces, the velocities are alio as the forces. For, becaufe the changes of the fquares of the velocities are as the fpaces and forces jointly, they are in this cafe as the fquares of the forces or of the fpaces ; but the changes of the fquares of the velocities are in this cafe the whole fquares of the velocities; therefore the fquares of the velocities are as the fquares of the forces, and the velocities are as the forces. N. B. This includes the motions reprefented in fig. 17. If two particles be Jimilarly Impelled along given 1C9. fpaces, from a Jlate of rejl, the fquares of the times are proportional to the fpaces direltly, and to ihe forces in- verfely. Let ABC (fig. 19.) abe be the fpaces defcribed, and AD, a d, the accelerating forces at A and a Let V, B exprtfs the velocity at B, and 1;, b the velocity at b. Let GHK and g h khe curves whofe ordinates are inverfely as the velocities at the correfponding points of the abfciffa. Thefe curves are therefore exponents of the times (n° 99 ) Then, becaufe the forces aft fimi- larly, we have, by the lafl theorem, AC X AD : a c X a ^ = V^ B : 1)', b, = h b' : HB\ Therefore HB : h b = X^ ac X ad : \^ ACxAD, and therefore in 3 conftant ratio. Call this the ratio of m to n. But, fince the ordinates of the lines GHK, g h i are inverfe- ly as the velocities, the areas are as the times {11° ^g) ; 2nd DYNAMICS. 537 Of Accede- and fince thefe ordinates are in the conftant ratio of m tatiiij; and (^ „^ tj,g areas are in the ratio of AC Xm to ei cXn. Kctardin); 'i-i,g,.efure (calling the times of the motions T and/), liave T ! Or T' ;/ r:mAC:nac;and therefore ■.l' = m'XAC':n'Xac^. But ;n'= ac Xa^: AC X AD. Therefore : /■ = a f X a (/ X AC : AC X AD X a C, -.1^= ad X AC : AD X a c AC ac Or T- : /^ = ^-fs : —j. AD arf The attentive reader will obferve that thefe three propofuions give a great extenfion to the theorems which were formerly deduced from the nature of uni- formly accelerated motion, or of uniform aftion of the forces, and were afterwards demonftrattd to obtain in the momentary aftion of forces any how variable. The lirft of the three propofitions, V : v = F X T : fX t, is the extenfion of the theorem /X t ■= v. The fecond, V^ : i)" = F X S :/X J, is the extenfion of the S / theorem/X J = f t). And the third, T' :'»= P : t' is the extenfion of /"= -J—, or of/X (/') = /. Thefe theorems hold true of ?A\fmilar aftions ; and only for this reafon, are true of uniformly accelerated motions, or uniform aftions. ^-»rcj,jte There remains one thing more to be faid concerning if many the aftion of accelerating forces. Their magnitude is , 1"^! ^"^'- afcei-taincd by their efFeft. Therefore that is to be conlidered as a double force which produces a double quauiity of motion. Therefore when a body A con- tains twice the number of equal atoms of matter, and acquires the fame velocity from the aflion of the force F that anotlitr body a, containing half the number of atoms, acquires from the aftion of a force f, we con- ceive F to be double ofy. 'I hat this is a legitimate in- ference appears clearly from this, that we conceive the fenfible weight of a body, or that preffure which it ex- erts on its fupports, as the aggregate of the equal pref- fure, of every atom, accumulated perhaps on one point; as when the body hangs by a thread, and, by its inter- vention, pulls at fome machine. Without inquiring in what manner, or by what intervention, this accumula- tion of preffure is brought about, we fee clearly that it refults from the equal accelerating force of gravity act- ing immediatly on each atom. When this weight is thus employed to move another body by the interven- tion of the thread, which is attached to one point per- haps of that body, it puts the whole into motion, gene- rating a certain velocity ii in every atom, by atting uniformly during the time /. We conceive each atom to have fuftained the adlion of an equal accelerating force, forces propagated to each atom of the impelled body. Of Accele. ^ rating and and meafured by — . If we know that the impelled Kcarding; ' / ^ Forces, body contains the number m of atoms, the aggregate of ' ■■ v ■■' forces is m — , or . But fiuce we meafure forces by the quantity of mo. tion which they produce, we mull conceive, that when the fame force is applied to a body « hid. coiifills of n particles, and produces the velocity u, by ading uni- a formly during the fame time /, the force n — is equal to V the force m - . Ito Sir Ifaac Newton found it abfolutely necefTary, in Movini^ the difquifitions of natural philofophy, to keep this cir-f^ i' orce; pofe that the body is not defleAed ; that is, is not ac- ' ted on by a tranfvcrfe accelerating force : And to fup- pofe that the tangent makes a finite angle with any part of the path, is to fuppofe that the deflexion is not continual, but by flarts — both of which are contrary to the conditions of the cafe. No ftraight line can be drawn between the direftlon of the body and the fuc- ccedlug portion of the path, otherwife we muft again fuppofe that the defleftion is fubfultory, and the mo- tion angidar. But while the inveftigation is fo eafy when the direc- tion and intenfity of the defletting force in every point of the curve are known, the inveftigation of the dffiec- ting force from the obferved motion is by no means eafy. The obferved curvilineal motion always arifes from a compofition of a uniform motion in the tangent with fome tranfvcrfe motion. But the fame curvilineal motion may be produced by compounding the uniform motion in the tangent with an infinity of traafverfe mo- tions ; and the law of aftion will be different in thefe tranfvcrfe motions according as their direftions differ. AVe muft learn, not only the intenfity of the deflefting force, and the law of its variation, but alfo its dire£lion in every point of the curve. It is not eafy to find ge- neral rules for difcovering the direction of the tranfvcrfe force; moft commonly this is indicated by extrinfic cir- cumftances. The deflefting force is frequently obfer- ved to refide in, or to accompany, fome other body. It may be prefiimed, therefore, that it afts in the direc- tion of the line drawn to or from that body ; yet even this is uncertain. The moit general rule for this invef- tigation is to obferve the place of the body at fcveral intervals of time before and after its paffing through the point of the curve, where we are intercfted to find its precife direftion. We then draw lines, joining thofe places with the places of the tangent where the body would have been by the uniform motion only. We (hall perhaps obferve thefe lines of junftion keep in parallel pofitions : we may be alTured that the dIreAion of the tranfvcrfe force is the fame with that of any of thefe lines. This is the cafe in the example juil now given of a parabolic motion. But when thefe lines change pofitlon, they will change it gradually ; and their pofi- tion in the point of contaft is that to which their pofi- tions on both fides of it gradually approximate. But all this is deftitute of the precifion requifite in philofophical difcuffion. We are indebted to Sir Ifaac Newton for a theorem which afcertains the diredlion of the tranfvcrfe force with all exaftnefs, in the cafes in which we moft of all wiflt to attain mathematical accu- racy, and which not only opened the accefs to thofe difcoveries which have immortalifed his name, but alio pointed out to him the path he was to follow, and even marked his firft ileps. It therefore merits a very par- ticular treatment. If a body defcribes a curve line ABC, DEF (fig. Newton': 21.) lying in one plane ; and if there be a point S fofunJamcrj lltuated in tliis plane that the line joining it with the"' '^^"^'j body defcribes areas ASB, ASC, ASD, &c. propor-^|.^io„oji tional tu the times in which the body defcribes thedefleflint arches AB, AC, AD, &c. the force which defleds the force, body from rectilineal motion is continually diretSed to the iixed point S. Let 114 ndicite coincides with BS, and the defledling force at B is direfted toward S. By the fame argument, the deflefting force at the angles D, E, F, &c. is directed to S. Now, let the fides of the polygon be diminifhcd, and their number increafed without end. The demonftia- tion remains the fame; and continues, when the polygon finally coalefces with the curve, and the defleftion is continual. When areas are defcribed proportional to the times, equal areas are defcribed in equal times ; and therefore the defleftion is always direfted to S. Q^ E. D. The point S may, with great propriety of language, be called the Centre of Deflection, or the Cen- tre OF Forces ; and forces which are thus continual- ly direfted to one fixed point, may be diftinguilhed from other deflefting forces by the name Central j Forces. I The line joining the centre of forces with the body, j and which may be conceived as a ftiff line, carrying the Radius vec- body round, is ufually named the Radius Vector. ' "■• The converfe of this propofition, viz. that if the de- '' 'entrd for A'^'^'ng forces be always direfted to S, the motion is : M produce P'^''f^o'"f"fd in one plane, in which S is fituated, and reas pro- areas are defcribed proportional to the times — is eafily ' ortional toj^j^onftrated by reverfing the fteps of this demonttra- '■ tion. The motion will be in the plane of the lines SB and Be; becaufe the diagonal BC of the parallelogram of forces is in the plane of the fides. Areas are de- fcribed proportional to the times ; for C c being pa- rallel to SB, the triangles SCB and S c B are. equal ; and therefore SCB and SAB are equal, Sec. &c. 'elocity is ^'"'- ^- When a body defcribes areas round S pro- iverfely a-portlonal to the times, or when it is continually deflec- I le perpeii-ted toward S, or afted on by a tranfverfe force direfted to S, the velocities in the diflerent points A and E of the curve are inverfely proportional to the perpendicu- lars Sr and St, drawn from the centre of forces to the tangents in thofe points; that is, to the perpendiculare from the centre on the momentary direftions of the motion : For fmce the triangles ASB, ESF are equal, 117. ri8 as arc .'entre of efledtion. lentre of )rces. 'entral >rce;. icular •om the SDtre. DYNAMICS. 5;,9 their bafes AB, EF are inverfely as their altitudes Sr, Of D-.flcft- St. But thefe bafes, being defcribed in equal timcP, '"'• *•'""•; are as the velocities ; and they ultimately coincide with " ' " the tangents at A and E. Cor. 2. If B .1 and F' be drawn perpendicular to SA and SE, we have SAxB« = SExF,, and S A : SE = F ■ : B " : For SA X B « is double of the triangle BSA, and SE X F ' is double of the equal triangle SFE. Cor. ^. The angular velocity round S, that i.-;, theAn^uUr magnitude of the angle defcribed in equal times by the .''■'^''^'^'''" radius veftor, is inverfely proportional to the fquarc of Jii",q'j;'/r(_ the diftance from S. For when the arches AB, EF.f flu-di;:. are dimiiiifhed continually, the perpendiculars B * and'^' « from F ! will ultimately coincide with arches deicribed round '^' ""trc S with the radii 'SB and SF. Now the magnitude of"' '"""• an angle is proportional to the length of the arch which iTie;i(ures it direftly, and to the radius of the arch in- verfely. In any circle, an arch of two inches long mea- fures twice as. many degrees as an arch one inch long; and an arch an inch long contains twice as many de- grees of a circle whofe radius is twice as lliort. There- fore, ultimately, the angle ASB is to the angle ESF as B « to F !, and as SF to SB jointly ; that is, as B ■^ 1 X SF to F t X SB. But B „ : F , = SE : SA {Cor- 2.) Therefore ASB : ESF = SE X SF : SB X SA, = ultimately SE^ : SB\ This corollary gives us an oftenfible mark, in many very important cafes, of the aftion of a dcfltiiing force being always direfted to a fixed point. We are oftra able to meai'ure the angular motion when we cannot nieafure the real velocities. Having thus difcovered the chief circumdances which Intimate enable us to alcertain the direftion of the dellefting>:""ii(rdioi> force, we proceed to invcftigate the quantity of this de-' '^.'')"*- fleftive determination in the different points of a ciirvi-"i','e h1°hcr lineal motion. This is a more difficult talk. The mo-gejtnary. mcntary elfeft of the deflefting force is a fmall devia- tion from the tangent ; and this deviation is made with an accelerated motion. The law of this acceleration regulates the curvature of the path, and is to be deter- mined by it. We m.ay be allowed to obferve by the way, that it appears clearly from the form in which Newton has prefented all his dynamical tlicmetTis, that we are indebted to thefe problems for the inimenfe in- provenient which lie has made in geometry by his in- vention of fluxions. The purpoft-s he had in view fuT- gcflcd to his penetrating mind the means for attaining them ; and the conneftion between dynamics and geo- metry is fo intimate, that the fame theorems are in a manner common to both. This is particularly the cafe in all that relates to curvature. Or (liall we fay thiit the geometry of Dr Barrow fuggefted the dynamical theo- rems to Newton? AVc have feen how the curvature of a parabola is produced by a force afting uniformly. The viomentary aftion of all finite forces may be confidercd as uniform ; and therefore the curvature will be that of fome portion of fome parabola; but it will be difficult to determine the precife degree without fiinie farther help. We arc beft acquainted with the properties of the circle, and will have the cleared notions of the curvature of other curves by comparing them with circles. The curvature of a circular arch of given length isMeafureof fo much greater as its radius is fliorter ; for it will coii-'"'^^""''' tain fo many more degrees in the fame length ; and 3 Y a therefore 540 Ot Deflf a ing I''orces. 119 JE volution and involu tion of curves. DYNAMICS. Circle of curvature. Equicurvc circle. thsrefore the cliange of direftion of its extremities is fo much greater. Curvatures may always be meafuved by the length of the arch diredtly and the radius in- verfely. Suppofe a thread made faft at one end of a material curve ABCD (fig 22 ), and applied to it in its whole length. Taking hold of its extremity D, unfold it gra- dnally from the curve DCBA ; the extremity D will dcfcribe another curve D c 1/ a This geometrical ope- ration is called the F.volutiojj of curves, and D c i a is called the Evolu r£ of DCBA, which is called the Involute of D i l"'- Perhaps this denomination has been given from the gcnefis of the area or furface con- tained by the two lines, which is folded up and unfold- ed fomewhat like a fan. When the defcribing point is in b, the thread 3 B is, undoubtedly, the momentary radius of a circle e bf, whofe centre isB, the point of the involute' which i't is juil going to quit._ The mo- mentary motion of i is the fame, whether it is defcri- bing an arch of the evolute paHing through i, or an arch of a circle round the centre B. The fame line tt, perpendicular to the thread I B, touches the circle ebf and the curve D b a in the point /'. This circle e i/muft lie within the curve Dirt on the fide of 3 B toward a; becaufe on this fide the momentary radius is continually increafing. For fimilar reafons,^ the circle e bf lies without the curve on the other fide of i B. Therefore the circle ebf both touches and cuts the curve D ba it\ the point b. Moreover, becaufe every portion of the curve between b and D is defcribed with radii that are fnorter than Z>B, it mud be more incur- vated than any portion of the circle ebf. For fimilar reafons, every portion of the curve between b and a muft be lefs incurvated than this circle ; therefore the circle has that precife degree of curvature that belongs to the curve in the point b ; it is therefore called the Equicurve Circle, or the Circle op Curvature, and B is called the centre, and B* the Radius of Curvaturk. It is eafy to perceive that no circle can be defcribed which fhall touch the curve in b, and come between it and the circle ebf; for its centre muft be in fome point i of the radius b B. If i b be lefs than B b, it muft fall within the curve on both fides of b, and if i b is greater than B b, the circle muft fall with- out the curve on both fides of B b. The circle e bf lies clofer to the curve, has clofer contaft with it than any other, and has therefore got the whimfical name of Osculating Circle; and this fort of contad was called Osculation. This view of the gcnefis of curve lines is of particu- lar ufe in dynamical difeulTions. It exhibits to the eye the perfeft fameuefs of the momentary motion, and therefore of the momentary defleftion, in the cun-e and in the equicurve circle, and leaves the mind without a doubt but that the forces which produce the one will produce the other. A great variety of curves may be defcribed in this way. If perpendiculars be drawn to the curve D ia in every point, they will interfed each other, each its immediate neighbour, in the circumfc. rence of the curve DBA: and geometry teaches us how to find the curve DBA which (hall produce the curve J) ba by evolution. See Evolution and Involution, Supphntent. It is a matter worthy of remark, that the path of a body that is deflefted from reftilineal motion by a fi- nite force, varying according to any law whatever, may Of Dcflcfl. always be defcribed by evolution. This includes alinoft '"-' l'"'>"t8. every cafe of the action of deflefting forces ; none be- • ing excepted but when, by the oppolite adllon of difi'e- rent forces, the body is in equilibrio in one fingle point of its path. Our tailc is now brought within a very narrow com- pafs, namely, to meafure the defleftion in the arch ot a circle. Had the TTU)tion reprefented in fig. 21. been poly, gonal, it is plain that the deflefting force in the point B is to that in the point E as the diagonal B A of the parallelogram ABC 3 to the diagonal Ei ot the pa- rallelogram DEFi; therefore let ABCZY be a circle pafiing through the points A, B, and C, and let the radius veftor BS cut the circumference in Z ; draw AZ, CZ, and the diagonal AC, which neceflarily bi- fetts and is bifefted by the diagonal B b. The tri- angles bVjC and CBZ are fimilar ; for the angle CAB is equal to the alternate angle ABA or ABZ, which is equal to the ACZ, {landing on the fame chord AZ. And the angle CB b, or CBZ, is equal to C.\Z, ftanding on the fame chord CZ ; therefore the re- maining angle iCB is equal to the remaining angle AZC; therefore Z.\ is to AC as BC to B i, and Bi ACXBC In like manner E / = DFxEF AZ D« Now let the points A and C continually approach, and ultimately coalefce with B ; it is evident that the circle ABCZY is ulimately the equicurve or coinci- ding circle at the point B, and that AS ultimately coa- lefces with, and is equal to, BS, and that AC X BC is ultimatelv 2 BC' ; therefore ultimately BA : E« = zBC^ . 2EP ._BC.EP "WT ' E^ ' "' ~ \V>Z ■ iEz* Now BC and EF being defcribed in equal times, are Meafareo* as the velocities: BA and Ej are the meafures of thedelleding velocities which the defleftlve forces at B and E would fjrce«. generate in the time that the body dtfcribes BC or EF, and are therefore the meafures of thofe forces. Thev are as the fquares of the velocities directly, and in- verfely as thofe chords of the equicurve circles ivhich have the diredions of the deflection. Obferve, that BA or Ei is the third proportional to half of the chord and the arch defcribed ; for B A : BC = BC:^. 2 It is evident th»t as the arches AB, BC, conti- nually dimlnifh, AC is ukimately parallel to the tau- ■rent B r, and BO is equal to the aftual deflexion from Uie tangent. The triangles BOC and AOZ arc fimi- lar, and BO = -^^ , or ultimately =-^- We may meafure the forces by the aftual defledions, becaufe they are the halves of the meafures of the generated velocities; and we may fay that „„ The allual momentary dcJlcBion from, the tangent is a third MeiCare o£ proportional to the deJeClive chord of the equicurve circle deaeflioo. and the arch defcribed during the moment. Either of thefe meafures may be taken, but we muft Caution, take care not to confound them. The firft is the moft proper, becaufe the change produced on the body (which is the immediate efFeft and meafure of the force) is the determination, left inherent in it, to move with a D Y N A of Dcfltifl a certain Telocity. This is the meafure alfo wl.ich we jug Furco. gijt^d, [jy means of the differential or fluxionary cal- cuhis ; but the other meafure mud be i)lHaliied when our immediate obitft is to mark the aiiliial path of the body. What is now dch'vered coincides with wliat was more briefly dated in Astronomy, Suppl, n° 1 6. and is repeated in this place, becaule the Heps of this demonftration, which is Newton's, fo naturally termi- nate ill the equicuvve circle, and give at once the im- mediate meafure of the defleiling force : at the fame time tho reader n\u(l perceive that this meafure docs not depend on the force being always dirciJted to one centre ';' It is eruingh that the two fides of the polygon, in immediate turceninn, are dcf>.Tibed in equal times. This is neceffary in order that ABC b may be a paral- lelogram, and that the diagonals AC and B b may mu- tually bifeft each other. Thus have we obtained a meafure of defledling force, and, in the molt important cafes, a method of difcover- ing its direftion. It only remains to point out the re- lation between the intenfity of the force, the curvature of the path, and the velocity of the motion. Thefe three circumllances have a ncceflTary connection ; for we fee that the intenfity is expreffed bv certain values Arch 2 of the other two in the formula f == -ttt; ;> or f •' • 4Chcn-d •' 2BC , :r T)r^ • The defleflive velocity B ^ is acquired in the time that the body defcrihes BC ; therefore the defleftive velocity is to the velocity in the curve as B 3 to BC. The velocity B b is acquired by an accelera- ted motion along BO ; for while, by progreflive mo- tion, the body defcribes BC, it deftefts from the tan- gent through a fpace equal to the half of B b, becaufe the momentary aftion of the deflefting force may be confidered as uniform. The progreffive velocity BC may be generated by the fame force, uniformly afting through a fpace greater than BC ; call this fpace x. The fpaces along which a body mull be uniformly im- pelled in order to acquire different velocities, are as the iquares of thofe velocities; therefore Bi': BC^=: B : X ; but B /; : BC = BC : 4 BZ ; therefore B i^ : BC ^ = B /^ : 4 BZ, and B i : i BZ = B o : x, and B i : B «) =: 4 BZ : .V ; but B o is 4 of^B b ; therefore « is J of BZ ; that is, x%i, "^he velocity in any point cf a curviUneal path, is that luhich the defleSing forces in that point luould generate in the body by impelling it uniformly along one fourth part of the difleSlive chord of the eqiiiiurve circle. If the velo- city increafe, the chord of ihe equicurve circle muft increafe ; that is, the path becomes lefs incurvated. If the force be increafed, the curvature will alfo increafe, for the chord of curvature will be lefs. There is another general obfervation to be made on the velocity of a curviiineal motion, which greatly af- jj fills us in our invefligations. . jmiiari- !f -^l body defcribes a curve by the aiJion of a force . n of orbi always direSed to a fixed point, and 'varying according to \ Ith'di'r"'^ ""^ proportion luhatcver nf the diflanccs from that point, j proachto'""' 'f '^noz/jfr body, aded on by the fame centripetal I e centre, forte, move toivard the centre in a flraight line, and if in any one cafe of equal diflances from the centre of force the tzuo bodies have equal i-elocities, they luill have equal velocities in every other cafe of equal diflances from the (cntre. M I C S. 541 Let one body be impelled from A (fig. 2^.) toward Of Dcflefl- C along the flraight line AVDEC, and lot another be'"K Forcet defletted along the curve line VI K k. About the ccn- '~~^'^~^ tre C dcfcribe concentric arches ID, KE, very near to each other, and cutting the curve in I and K, and the line AC in D ajid E"; draw IC, cutting KE in K, and draw NT perpendicular to the arch IK of the curve, and complete the parallelogram ITNO. Let the bodies be fuppofed to have eijti.il velocities at I and at D. Then, becaufe the centripetal forces are fuppofed to be the fame for both bodies when they are at equal dillaiices, the accelerating forces at D and I may be reprefented by the equal lints DE and IN ; but the force IN is not wholly employed in accelerating the body along the arch IK, but, afting tranfverfely, it is partly employed in incurvaiing the path. It is equi- valent to the two forces 10 and IT, of which only IT accelerates the body. Now IKN is a right-angled tri- angle, as is alfo the triangle INT ; and they are limilar; therefore IN : IT = IK : IN, cr DE : IT = IK : DE; that is, the force which accelerates the body along DE is to the force which accelerates the body along IK as the fpace IK is to the fpace DE ; therefore (n" 86.) the increment of the fquare of the velocity acquired along DE is equal to the increment of the fquare of tlie velocity acquired along IK. But the velocities at D and I were equal, and confequently their fquarcs were equal ; and thefe having received equal increments, therefore the fquares of the velocities at E and K are equal, and the velocities themfelves are equal. And finc« this is the cafe in all the correfponding points of the line AC and the curve VI K, the velocities at all equal diflances from C will be equal. It it evident that the conclufion will be the fame, if the bodies, i'nftead of being accelerated by approaching the centre in the flraight liue'AC, and in the curve- VI K, are moving in the oppolite direClions from E to A, or frotri I to V, and are therefore retarded by the centripetal force. Cor. Hence it follows, that if a body be projected Retarded from any point, fuch as V, oHhe curve, in a line tend-'^"".'''""^ ing flraight from the centre, with the velocity which itwayrac- " had in that point of the curve, it would go to a diltancecompanied VA, fuch, that if it were impelled along AV by thebyrecefi centripetal force, it would acquire its former velocity in'^'^""' '*'' the point V ; alfo in any point between V and A Jt"^""'- will have the fame velocity iii its recefs from the centre that it has there in its approach to the centre. The line BLFG, whofe ordinatcs are as the intenli, ties of the centripetal force in A, V, D, E, or in A, V, I, K, may be called the scale or exponent of force; the arei.s bounded by the ordinates AB, VL,. DF, EG, occ. drawn from any two points of the axis, are as the fquares of the velocity acquired by accelera- tion along the intercepted part of the axis, or in any curviiineal path, while the body approaches the centrCj or which are loll while the body retires from it. When we can compute thefe areas we obtain the velocities (fee n° io2.). We are now in a condition to folve the chief pro- blem in the fcience of dynamics, to which the whole of it is, in a great meafure, fubfervient. The problem is this, Let a body be projefted with a known velocity from 542 Of ocfl a- in|r Force-. 114 !nv?riepro h'em of fcntripetal fu) c«t. DYNAMICS. Inverfe pro Mem of centriijetal forces. a given point anJ in n given dircflion, and let it be un- der the influence of a mechanical force, whofe diredlion, inteniity, and variation, are all known : it is required to determine its path, and its motion in this path, for any given time ? Thh problem is fiifceptible of three diftinft clalTes of conditions, which require different inveftigation. t. The force may aft in one conftant direftion ; that is, in paralkl lines. 2. The force may be always direfted to a fixed point. 3. It maybe direfled to a point which is continually changing its place. I. When the force afts in parallel lines, the problem ia folved by compounding the reftihneal accelerated motion whiih the force would produce in its own direc- tion with the uniform motion which the projeftion a- lone would have produced. The motion mull be cur- vihneal, when the accelc,rating force is tranfverfe, in any degree whatever, to the projeftile motioa ; and the curvilineal path niuft be concave on that fide to which the deflefting force tends ; for the force is fuppofed to aft inceflantly. The place of the body will be had for any time, by finding where the body would have been at 'he end of that time by each force afting alone, and by completing the parallelogram. Thus, fuppofe a bo- dy projefted along AB (fig. 20.) while it is continual- ly afted on by a force whofe diretlion is AD. Let D and B be the places where the body would be at the end of a given time. Then the body will at the end of that time be in F, the oppofite angle of the paral- lelogram ABFD. But it has not defcribed the diago- nal AF ; becaufe its motion has been curvilineal, as we (hall find by determining its place at other inftante of this time. The velocity in any point F is found by fifft deter- mining the velocity at D, and making DT to DF as the velocity at D to the velocity at B (that is, the ve- locity of projeftion, becaufe the motion along AB is uniform). Then draw TF. Then AB is to TF as the conilant velocity of projeftion to the velocity at F. We have feen already (no i i 2 — 1 19.) that TF is a tan- gent to the curve in F. Hence we may determine the velocity at F in another way. Having determined the iorm of the path in the way already defcribed, by find- ing its different points, draw the tangent F d, cutting the line DA in d. Then the velocity at A is to that at F as AB to ii¥. Hence alfo we fee, that the velo- cities in every point of the curve are proportional to the portion of the tangents at thofe points which are inter- cepted between er,y two lines parallel to AD. Either of thcfe methods for ajcertaining the velocity, in this cafe of parallel deficftions, will in general be eafier than the general method in n' 121. by the tqui- curve circle. It was thus that Galileo difcovered the parabolic mo- tion of heavy bodies. 2 We muft confider the motions of bodies afFefted by centripetal or centrifugal forces, always tending to one fixed point. This is the celebrated inverfe problem of centripetal forces, and is the 42d propofition of the ilft book of Newton's Principia. We fliall give the folution after the manner of its illuftrious author ; be- caufe it is elementary, in the puicll fenfe of the word, la;. keeping in view the two leading circumflancc!, andOfDfflcft. thcl'e only, namely, the motion of approach and lecefs'"*! Foiccj. from the centre, and the motion of revolution. By v^™' this judicious priicefs, it becomes a pattern by which more refined, iind, in f.mie refpeft:, better iolutions (hould be modelled. At the fame time we Hiall fupply fome fteps of tiic inveftigation which his eletjant concife- nefs has made him omit. Let a body, which tends to C (fig. 24 ) with a force proportional to tlie ordinates of the exponent BLFG, having the axis CA, be projefted from V in the direc- tion VQ, witli the velocity which the centripetal force would generate in it by accelerating it along AV. It is required to determine the path or orbit VIKI cf the body, and its place 1 in this orbit, at the end of the af- figned time T ? Suppole the thing done, and that I is the place of the body. About the centre C, with the diilances CV and CI, defcribe the circles YV and ID. Draw CIX to the circumference, and draw the ordinate DF of the exponent of forces, producing it toward .v, and produce the ordinate VL toward a. Let V / be the diftance to which the body would go along the tangent VQ iu the time T, and join / C. Let this be fuppofed done for every point of the curve. Let a i it and axy be two curves fo related to the curve VIK, that the ordi- nate DF cuts off an area V a / D equal to the orbital feftor VCI, and an area V a x H equal to the circular feftor vex. Then, becaufe the velocity of projeftion is given, the dillance V / is known, and the area of the triangle VC t. But this is equal to the area VCI, by the laws of central forces (n° 115.). Therefore the area Va/D is given. Alfo, becaufe the area VCI increafes in the proportion of the time, the area V a i D increafes at the fame rate. Therefore having thcfe fubfidiary curves a i k, axy, the problem is folved as follows : Draw an ordinate D (, cutting off an area V a ;' D proportional to the time, and defciibe a circle DIR. Then draw a line CX, cutting off a fetter VCX, equal to the area V a x D cut off by the ordinate Hix. This line will cut the circle DR in the point I, which is the point of the orbit that was demanded. But the chief difficulty of the problem confifts in the defcription of the two fubfidiary curves ai k and a x y, into which the lines VIK and VXY are transformed. We attain this conftruftion by refolving the motion in the arch of the orbit into two motions, one of which is in the direftion of the tranfverfe force, or of the ra- dius veftor, and the other is in the direftion of revolu- tion, or perpendicular to the radius. Let V k and IK be two very fmall arches defcribed in tqua] moments, and therefore ultimately in the ratio of the velocities in V and I (n° 73.). Defcribe the circle KE, cutting IC in N. Draw KG and i C, and k n perpendicular to VC. IC X KN The element ICK of the orbit is = , or 2 ' to -J IC X KN. This is equal to the element D i i E of the area V a i D, or to D i X DE, or to D / X IN. Therefore IN : KN = 4^ IC : D ;", or 2 IN ; KN = rr, T. • , ^ ICXKN IC : D /, and D i = tv-t 2 IN Novv let A Ifg h be the exponent of the velocities, that D Y N A OfDenefl-that I's (no 86.), let V / ' be to D/' as ABLV to ilif^ ABFD,orV/:D/= V'ABLV: a/ABFD. Make V V and I ;' in the tangents refpeClively equal to V / and Dy. Draw -v u and /' o perpendicular to VC and IC, and V m pcrpendiciili.r to LV produced. Let m r z be an equilateral hyperbola, having VC, ZC, for its aflyniptotes, and cutting FD produced in r. Then the ordinates V iti, D r, arc invtrfely proportional to CV, CD, or V »; : D r = CD : CV, = CI : CV. But becaufe the momentary fedtors VC i and ICK are eq^ual, i n : KN = CI : CV. Therefore, V ffl : D ,=;(•«: KN but y v -.V m = V i : i n and i; (or D/) : Vt> = IK : V/5 therefore I »' : D r = IK : KN but I » : «' ;= IK : KN, by iim. triang. Therefore D /• = i o, and « o : V m = VC : CI. Alfo, by (imilarity of triangles, I o : / a = IN : KN, and 2 I : /' = 2 IN : KN. Now it was (hewn, that in order that the fpace D i i E may be equal to the fpace ICK, wc mud have 2 IN : KN = IC : D i or 2 I : i = IC : D / but «■ : V m = VC : IC therefore 2 I o : V w = VC : D- « ,^. VCXV;« and D z = ■ ^f • 2 I Having obtained D i, we eafily get D x ; for the ul- timate ratio of ICK to XCY is that of IC to VC. Therefore make 1C= : VC^ = D <■ : D AT. Thus are the points of the two fubfidiary curves aii, axy, determined. The redlangle VC X V m is a conftant magnitude ; and is given, becaufe VC is given, and V m is the given velocity V /, diminilhed in the ratio of radius to the line of the given angle CVQ- But the line 2 I o is of variable magnitude, but it is dfo given, by means of known quantities. I o^ is = I n-i o'= D/'— 1) r\ and I o = ^ITf^—Hr'. \& X V m"- Moreover, D/' = ABFD, and D''= IC^ Therefore 2 I 0= 2 J ■ ABFD — —^-^^-l, ex. VC=_XV "IC^" preflTtd in known quantities, becaufe ABFD is known from the nature of the centripetel force. Let the indeterminate didance CI or CD be i= x, and let the ordinate DF, eN.prefGng the force, be j'. Let VC be a, and V m be c, and let a i be a reflangle equal to the whole area of the exponent of force lying be- tween the ordinate AB and the ordinate CZ, fo that ah — I y X may reprefent the indeterminate area ABFD. a c We have D i z= and D K .= y~ . a- c'- ab-Jyx --^ a ' c ^.J ab-fyx -^ Remark. We have hitherto fuppofed that the ve. locity of projeftion is acquired by acceleration along AV. But this was merely for greater fimplicity of ar- M I C S. ^^^ gument, and that the final values of D i and D x might Of Dcflecft- be eafier conceived. In whatever way the velocity is "'V. ^'urces. acquired, it will (lill be true, that when in any point V ' ' ■v/i: make V / to V m as the momentary increment V k of the arch is to the perpendicular /■ n on the radius vec- tor, we (hall have in every other point, fuch as 1, the line D/to the line D r as the increment IK of the arch to KN. And in the final equation D/will (lill be exprclTed hy ^y a b — /' Cor. I. The angle which the path of the projeflile ufi, makes with the radius veftor is determined by this fo- lution ; for I i is to i o as radius to the fine of this angle ; which fine is therefore := Wab—Jy^, Cor. 2. When the magnitude is equal to */ ab — I'y X, t^ie path is perpendicu'ar to the radius vec- Apfide/de-- tor, and the body is a tone of the apfides of its orbit, and '"■"'"''^ > begins to recede from the centre after having approach- ed to it, or begins to approach after having receded. ,2S Cor. 3. The curvature of the orbit VIK is alfo de- Ar\ii curva.- termined in every point; for the curvature of any line'""- is inverfely as the radius of the equicurve circle, and this is to the chord which pafFes through C as radius to the fine of the angl e CI r. Becaufe the velocity in any point I is = V ABFD, and is equal to what the centri- petal force at I would produce, by impelling the body along ^th of the deileftive chord of the equicurve circle, . , ABFD we have this chord = 4 — Typ — Or we obtain it by taking a third proportional to the momentary deflexion and the momentary arch of the curve, or by other pro- ccfTes of the higher geometry, all proceeding on the quantities furnilhed in this invelligatiun. Such is the folution of this celebrated problem given I^I^.v^,'n',(,p.. by Sir Ifaac Newton, who may juftly be called the in- inventor, ventor of the fcience of which it is the chief refult, as well as of the geometry, by help of which it is pro- fecuted. For we cannot give this glory to Galileo ; for his fimple problem of the motion of bodici a(fe£\ej by uniform and parallel gravity, however juft and ele- gant his folution may be, was peculiar ; and the fame mull be faid of Mr Huyghens's doClrine of centrifugal forces. Befides, thefe theorems had been invciligated by Newton feveral years before, y"«a mathejl facem prc- fercnte, as corolhries which he could not pafs unnoticed, from his general method. This is proved by letters from Huyghens. Newton's invedigation is extremely, but elegantly, concife, and is one of the bed exertions of his fagacious mind. Whether we coiifider this problem as a piece of mercHiftorv cf mathematical (peculation, or attend to its conrequences,this pro- which include the whole of the celedial motions in allb'em. their extent and complication, we mud allow it to be highly intertding, and likely to engage much attention in the period of ardent inquiry wlu'eh clofcd the lalt century. Accordingly, it was no fooner known, by the publication of the Alatljemaiical Princ'iphs of Na- tural Ph'ilof'jphy in 1686, than it occupied the talents of the mod eminent niatheui.iticians ; and many folu- tions were publifiied, fome ot which differ confiderably from Newton's ; fome are more expeditious, and better*' fitted for computation. Of thefe, the mod remarkable .- foxx 544- DYNAMICS. of Dcfleil for originality and ingenuity are thofe of de Moivre, .•"g '•"°"'''; Hermann, Keill, and Stewart. The laft differs moft ' from the methods purfued by others. M'Laurin's pro- pofitions on this fiibjeft, and in that part of his fluxions which treats of curvature, are highly valuable, clading the chief affcdions of curvilineal motions geometrical- ly, as they are fuggefted by the fluxionary method ; and then (hewing, in a very indrndive manner, the con- nexion between thefe mathematical afi"eftions of motion and the powers of nature which produce them. This part of his excellent work is a fine example of the real nature of all inquiries in dynamics ; fhewing that it dif fers from geometry little more than in the language, in which the word force is fubftituted for acceleration, re- tardation, or dejledion. We recommend the careful per- ufal of thefe propofitions to all who wifh to have clear conceptions of the fubjeft. Dr John Keill and Dr Horfeley (bifhop of Rochefler) have given particular treatifes on the motions of bodies deflefted by centripe- tal forces inverfely proportional to the cubes of the dif- tances ; induced by the fingular motions which refult from this law of adlioii, and the multitude of beautiful propofitions which they fugged to the mathematician. Newton, indeed, tirft perceived both of thefe peculiari- ties, and has begun this branch of the general problem. He firll demonllratcd the dtfcriptlon of the logarithmic and hyperbolic fpirals, and indicated a variety of curi- ous recurring elliptical fpirals, which would be defcri- bed by means of this force, and (hewing that they are all fufceptible of accurate quadrature. Several of thofe authors affeft to confider their folutions as more per- feft than Newton's, and as more immediately indica- ting the remarkable properties of fucli motions; and alfo affeft to have deduced them from different and original principles. But we cannot help faying, that their claims to fuperiority are very ill founded ; there is not a prin ciple made ufe of in their folutions which was not pointed out by Newton, and employed by him. The appearance of originality arifcs from their iiaving taken a more particular concern in fome general property of curvillneal motions ; inch as the curvature, the centri- fugal force, &c. and the making that the leading ftep of their procefs. But Newton's is dill the beft ; becaufe It is ftriclly elementary, aiming at the two leading clr- cumftances, the motion to or from the centre, and the motion of revolution round that centre. To thefe two piirpofes he adapted his two iubfidiary curves. This procedure became Newton, pater, el rerum inventor, who was teaching the world, and who might fay, jivia Fieri Jum peragro loca, nuIUus ante Trita peile Sinffukr Is it not furprlfing, that 25 years after the puhlica- boaft of ti'on of Newton's Principia, a mathematician on the n ull ' <^ont'nf"t (hould publiih a folution in the Memoirs of the French academy, and boaft that he had given the firft demonftration of it ? Yet John Bernoulli did this in 1710. Is it not more remarkable that this rtiould be preclfely the folution given by Newton, beginning from the fame theorem, the 40th I. Prin. following Newton in every ftep, and ufing the fame fubfidiary lines ? Yet fo it is. Bernoulli aftually reduces the whole a c to two funftions; namely,' and / a b X* — f f ^* — "^ <:^ • plainly the fame with Newton's ^-=.; which lalt IS Ing force. Q_y CX' A' v'ABDF — Z'J ^ oh — ^t t — becaufe Newton's-r— is the fame with — ,and Newton's -♦ .V AVACFD — ZMs the fame with .v' /a i>—/, x — a"- c^ 1 — , which Bernoulli has changed (apparently to hide the borrowing) into / a b x* — j p x* x — a' <:» x'. This publication of Bernoulli Is perhaps the moft impu- dent piece of literary roblcry, for theft is too mild a term, that has ever appeared; and is the more deferving of fevere reprehenlion, becaufe it is full of lefledllons on the fimple and iupremely elegant method of Newton. It is hardly conceivable that a perlon of Bernoulli's con- funmiate mathematical knowlege was fo much blinded by the mechanical procedure of the fymbolical calculus (which indeed is rarely accompanied by any Ideas of the fubjeft in hand) as not to perceive the perfett famenefs of his folution. No ; he ftiews, from time to time, that the phyfical ideas of motion and force were prcfent to his mind ; for he affefts to fiiew, that all Newton's brighteft difcoverles, fuch as the proportionality of the areas and times, &c. flow as corollaries from his proce- dure. Bernoulli's chief boaft in this difTertation is, that new philofopliers may he affured that the planets will always dcfcribe conic fedllcns; a truth of which they had not as yet received any proof: becaufe, fays he, Newton's argument for it in the corollary of the i ^th propofitlon is inconclufive, and becaufe he had not been able to ac- commodate his demonftration of the 41ft and 42d pro- pofitlon to the paiticular cafe of the planetary gravita- tion. Two affertions that border on Infolence. New- ton's demonftration in the corollary of thfe 13th propo- fitlon is juft, founded on the principle on which the very demonftration of the 42d, adopted by Bernoulli, pr»- ceeJs, and without which that demonftration is of no force; namely, that a body in given circumftances of fi- tuation, velocity, diretlion, and centripetal force, can defciibe no other figure than what it really defcrlbes. Newton did not accommodate the demonftration of the 42d propofitlon to the planetary motions, becaufe he had already demonftrated the nature of their orbits; but mentions the cafe of a force proportional to the recipro- cal of the cubes of the diftance ; not as a dcduftion from the 42d, but becaufe it 'was not a dedu6tIon from It, and admitted a very lingular and beautiful inveftigation by methods totally and eflentially different. Bernoulli alfo fays, that Newton's folution does not give us the notion of a continuous path, as his own does, but only informs us how to afcertain points of this path. This is the boldeft of all his affertions. Bernoulli ufes the differential calculus. It is the ejfential charafter of this calculus that it exhibits, and can exhibit, nothing but detached points. This is undeniable. And this has been objefted to Newton's firft propofitlon. But New- ton's fluxionary geometry, of which the calculus exhibits only elements (being the fame with the differential), fuppofes DYNAMICS. 545 'nrclunon.fuppofes the continuity of all magnitudes ; and when fcfTcs to involve no notions but thofe 6f force, and its ConchC, - » applied to dynamics, is no fuhftitution whatever, but marks and meafures. >—— y-_ tlie (//) corpora. This geometry ofTcred itfclf to the NotwithfUnding thefe great omifiions, we niuft ob- mind of Newton, the accompliflicd and darling fcholar ferve that no new principle remains to be confidered. of Barrow, whofe geometry fl:\(hed on Newton's mind We have given k11 that are necelfary ; and there is no as the torch whicli was to ihcvv him the fteps of this queilion that occurs in the cafesomitted, which cannot be yet untrodden path. completely anfwercd by means of the propofitions already We truft that our readers will not be difpleafed with eftabliilied. We have taught how to difcover the ex- our repeated endeavours to defend our great philofo- illence and agency of a mechanical ("orce, to meafure and pher from the_ injurious attacks that have been made charaaerife it, and then to (late what will he its various on him. During his own illuftrious life, while he was cffefts, according to the circumftances of the cafe, diffufmg light and knowledge around him, and never Proceeding by thefe principles, men have difco'vered «,*r^a/ contended for fame, happy in being the inllrndlor of an univerfal faft, that every action of one body on ano-'-''"?'"'' is a mankind, he was injured by thofe who ejivied his repu- ther is accompanied by an equal reaction of that q.'-*"'. ''^^ tation, while they derived their chief honours from be- ther on the lirft, in the oppofite direftion ; that is, to'^'"ij"' ing his beft commentators. Now, fince he has left this cxprefs it in the language of dynamics, " all the pheno.""" ' world, he has been more grofsly injured by thofe who mena which make us infer that the body A poifeffes a avail themielves of that very reputation : and who, by force by which it changes the motion of the body li crude and contemptible inferences from his doftrine of fliew, at the fame time, that B poiTeffes a foice by elailic undulations, and grofs mifreprefentations of his which it makes an equal and oppulite alteration in the notions of an efhenal fluid, have pretended to fupport motion of A." This, however, is not a doftrine of ab- a fyltem of matcnalifm ; and thus have fet Newton at ilrad dynamics : it does not flow from our idea of the head of the atheiRical fed, which he held in abhor- force ; therefore it was not included in oui liil of the rence. For our part, we always think with pleafiire on Laws of IVIot.on. It is a part of the mechanic-il the vvonderful energy ot that great mind; becaufe it gives hiftory of nature, juft as the law of univerfal gravitation us a toretalte of thole pleafures that await the wife and is ; and it miVht be called t" " ---'=■ good, when the forrows flowing from the iniirmitieS; the vices, and the arrogant vanity of man, are paft ; Utque in hoc InfcUci campo, Ubi lu3us regtiat, et pavor, Mortalihus prorfus mn abftt folatium. Hujus enhn fcrlpta evoivas, Menlemque tantarum reriim capacem Ccrpori caduco fuperjihem credos. ght be called the law of Unive'rsal Re- action. Sir Ifaac Newton has, in our humble appre- henfion, deviated from his accuflomed logical accuracy, when he admits, as a third axiom or law of motion. that reaftion is always equal and contrary to adlion. It is a phyiical law, in as far as it is obfrrvcrl to obtain through the whole extent of the folar fyftem. But.New- ton himfelf did not, in the fubfequent part of his noble work, treat it as a logical axiom ; that is, as a law of i-ii T, , ,, n , , . , ... I'uman thought with refpea to motion : for he labours nclufioii. - \l """°t be expeded that, m the narrow limits pre- with much folicitude, and with equal fafracltv, to prove fcribed to a work hke ours, we can proceed to confider hy faB and obfcrn,a,ion, that it really Obtains through the various departments of this celebrated problem, the whole extent of the folar fylk-m ; and it is in this V\ e are only giving the out mes of the general dodrines difcovery that his chief claim to unequalled penetration ot dynamics; and we have beflowed more time on thofe and difcernment appears ' t^l wf" ?r^^ elementary than fome readers may Availing ourfelves of this fad, we, with very little ,„!„Yfi think they^deferve. We were anxious to give juft con- trouble, ftate all the laws of impnlfion The body A P " n! ceptionso the fuiidamental principles of dynamics; be- for example, moving to the weftward at the raleo by't; nai of ^T a T"f^ '"^^ "". r"^%" '" "" "■°'' ^''' P^-- ■"''"''^' --"kes the double body B '^^^ -^,^q^"'^"ce_th3n equal and oppafite changes. ^ They muft give, in fome ,-n,Vtl, „„!,.■ e 1 V . ^ - - -y ^»'-"« 'XJi- lead- way or other, //;« indieation of pofltffing equal and op- ng thoughts of mechamfm It elf, and our notions of pofite forces. This will be the cafe if, wll the chan- ,^, the in imate nature of the vihble univerfe. g.s are completed. A and B move on^ n contad at the fc„3for Lut we mull conclude the article witli this great rate of four feet per minute : for here A hs prod iced Ifion,. problem Many very general doftrines of dynamics re- in each half of B a change of motion tl and re main untouched; all, namely that relate to the rotative fore a totality of chang^ equal to four This ithe motion of rigid bodies, and a 1 that relate to the mutual efl-ed, the mark, the mfafure, of the adnm of bodies on each other in the way of impulfe. :ie inipiil/i-ve force of •pL„ ,„, . ■ ■,,,„.' - ....J. A; tor it is tlie whole impidhon- B has produced in i'he rotative motions, with tlip /!/,«,■;„„ „f .„„.,t,„_:_ A a chantre f ' -^ • "f" F'"""*-"-" '" P f . ri - -- -— ,, „.^....^ in the oppofite ^^:MT:±'}fl'"y'': P'''""- ' ='■"'. "-^^ l"'"P-f<^ t" ■""'■ure, of the repulf.e force of A; for it is the whole e rotative motions, wi^th the dodrine of mechanic A a change of motion four,''equal to "th'e for"mer".nd momenta, have been confidered at large in the article in the opp^ofite diredion. Th.sl the effed, mTrk; ^"d f our7uVSent"toTh''"rT" Z ''' '''''''''ft,'^ T'l^''"' ^"^^ "''^''^ ^'' *'-' "-' "'^f-ve in the coll,- CHAH cs In he an-1. „ ■'" ^m"' " - -•" ^-"" °^ '"° ^"™P' °^ '''^ ' '"'^ '^' oblervation is one (uXa% ■ , Impulsion will be contidered of the fads on which the reality of the nhyfical Kw of th fpecffi?diff7 '" '"'^ rr> -'^ '"d^P- J"^t of ^^qual adion and readion is founded ' SVPPL Vo! I Part II DvN^Mics pro- no farther inference from //. fad. and we can make 3Z But 54=6 ConcIuGon 136 Ard rota- tion. D'Alem. btrc'sgene- »al princi- ple of d^na' Biici. D Y N A But the event ^ight have been very different. A and B may be two magnets floating on corks on water, with their north poles fronting each other. We know, by other means, that they really polTefs forces by which they equally repel each other. The dynam.ical prin- ciples already eftabliilied tell us alfo what muft happen in this cafe. That both conditions of equal reaftion and fenfible repulfion may be fulfilled, A muft come to reft, , and B muil move forward at the rate of four feet per minute. The lame thing mult happen in the meeting of perfeftly elaftic bcdies, fuch as billiard balls. If elafticities are known to be imperfeft in any degree, our dynamical principles will ftiil ftate the cffetl of their collifion, in conformity to the law of equal reaflion. In like manner, all the motions of rotation are explain- ed or predicted by means of the fame principles of dyna- mics applied to the force of cohefion. This is confider- ed as a moving force, becaufe, when the attraftion of a magnet afts on a bit of iron attached to one end of along lath floating on water, the whole lath is moved, although the magnet does not aft on it at all : fome other force afts on it ; it is its cohefion ; which is therefore a mo- ving force, and the fubjetl of dvnamical difcuffion. And thus it appears that thefe fubjefts do not come neceflarily, nor, perhaps, with fcientitic propriety, un- der the category of dynamics, but are parts of the me- chanical hillory of nature. Yet, did a work like ours give room in this place, the ftudy of mechanical na- ture might be conllderably improved by giving a fvftem of fuch genera! doftrines as involve no other notions but thofe of force and its meafures, and the hypothcfis of equal reaction. Some very general, nay univerfal, confequences of this combination might be eftablifhed, which would greatly affift the mechanician in the folu- tion of difficult and complicated problems. Such is the propofition, that the mulual actions of bodies depend on their relat'fo! motions only, and require no Incwledge of their real motions. This principle fimplifies in a won- derful manner the mo.ft difficult and the moft frequent cafes of aiftion which nature prefents to our view ; but at the fame time gives a fevere blow to human vanity, by forcing us to acknowledge that we know nothing of the real motion of any thing in the imiverfe, and never (hall know any thing of it till our intellcftual con- ftitution, or our opportunities of obfervation, are com- pletely changed. Mr D'Alembert has made this principle ftill more ferviceable for extricating ourfelves from the immenfe complication of a&ions that occurs in all the fpontane- ous phenomena of nature, by prefenting it to us in a different frm, which more diftlnftly exprefles what may be called the elements of the aftioiis of bodies on each other. His propofition is as follows {^fee Ins Dy- namique, page 73.) : " In whatever manner a number of bodies change their motions, if we fuppofe that the motion which each body would have in the following moment, if it were perftftiv free, is decompofed into two others, one of which is the motion which it really takes in confe- quence of their mutual aftions, the other will be fuch, that if each body were imprefled by this force alone (that is, by the force which would produce this motion) the whole fyftem of bodies would he in equilibrio." This is almoft felf-evident ; for if thefe fecond confti- tuent forces be not fuch as would put the fyftem in equilibrio, the other conftituent motions could not be M I C S. thofe which the bodies really take by the mutual adion, Condufi but would be changed by the firft. v— For example, let there be three bodies P, Q, R, and let the forces A, B, C, aft on them, fuch as would give them the velocities />, q, r, in any direftions what- ever, producing the momenta, or quantities of motion, PX^, QXy, RXr, which we may call A, B, C, be- caufe they are the proper meafures of the moving force. Let lis moreover fuppofe, that, by ftriking each other, or by being any how connefted with each other, they cannot take thefe motions A, B, and C, but really take the motions a, b, and c. It is plain that we may conceive the motion A impreffed on the body P, to be compofed of the motion a, which it really takes, and of another motion u. In Hke manner, B may be refolved into b, which it takes, and another ^ ; and C into c and «. The motions will be the fame, whether we aft on P with the force A, or with the two forces a and a ; whether we aft on Q_with the force B, or with b and /5 ; and on R with the force C, or with c and K. Now by the fuppofition, the bodies aftually take the motions a, b, and c ; therefore the motions =, /3, and «, mull be fuch as will not derange the motions a, b, and c ; that is to fay, that if the bodies had only the motions «, ^, and «, imprefled on them, they would dcilroy each other, and the fyftem would remain at reft. Mr D'Alembert has applied this propofition with great addrefs and fuccefs to the very difficult queftions that occur in the motions and aftions of fluids, and many other moft difficult problems, fuch as the precef- fion of the equinoxes, &c. The caule of its utility is, that in moft cafes it is not difficult to find what forces will put a fyftem in equilibrio ; and, combining thefe with the known extraneous forces whofe effefts we are interefted to difcover, we obtain the motions which really follow the mutual eftion of the bodies. This is not, properly fpeaking, a principle : it is a form in which a general faft may be conceived. In the fame way the celebrated mathematician De la Grange obferved, that a fyftem of bodies afting on each other in any way, is in equilibrio, if there be imprefled on its parts forces in the inverfe proportion, of the velocities which each body takes in coniequencc of their aftion or conneftion ; and he exprcftes this mii- verfal faft by a very fimple formula ; and calling this alfo a principle, he folves every qucftlon with eafe and neatnefs, by reducing it to the inveftigalion of thofe velocities. In this way he has written a complete fyf- tem of dynamics, to which he gives the title of Aleche- riqiie Amilytiqne, full of the moft ingenious and elegant foliitions of very intereftiiig and difficult problems; and all this without drawing a line or figure, but accom- plilhiiig the whole by algebraic operations. But thii is not teaching mechanical philofophy ; it is ijjr merely employing the reader in algebraic operations, each of which he perfeftly underftands in its quality of an algebraic or arithmetical operation, and where he may have the fuUeft conviftion of the juftnefs of his procedure. But all this may be (and, in the hands of an expert algebraift, it generally is), without any no- tions, diftinft or indiftinft, of the things, or the pro- ceflTes of reafooing that are reprefented by the fymbols made ufe of. It is precifely like the occupation of a banker's clerk when he carries his eye up and down the columns of pounds fhillings and pence, calculates the compouttd intereftj reverlionary values, &c. It onclurinn. Ifidvau D Y N A It were well if this were all, although it greatly di- miiiinies the pleafurc which an accoaiplilhcd mathema- tician might receive ; but this total abi'ence of idciis ex- pofes tviii the moll eminent analyft to frequent riilis of paralogifm and phyfical ajjfnrdity. Euler, who was perhaps the moll expert algcbraift of the lad century, making ufe of the Newtonian theorem for alcerf.iining the motion cf a body impelled along a (Iraight line AC (fig. 24 ) by a centripetal force, by compari.ig it with the motion in an ellipfe, of which the fhorter axis was diminiflied till it vaniihed altogether, exprell'es his fur- prife at finding, that when he computes the place of the body for a time fubfequent to that of its arrival at C, the body is back again, and in feme place be- tween C and A ; in Ihort, that the body comes back again to A, and plays backward and forward. He fays that this is fomewhat wonderful, and feems in- co'.ihlteiit wit'a found rcalon : "_/«/ analyji rna^is Jiihn- t!um" It mull: be fo. And he g'ocs on to another problem. In like manner Mr Maupertuis, an accomplilhed man and gf'iid philofopher and geometer, finding the iym- bol MVS, or the quantity of matter, multiplied b) the velocity and by the diifance run over during the ac- tion, always prefent itfelf to him as a mathematical mt- 7iimum in the adlions of bodies on each other ; he was amufed by the obfervation, and prefumed that there was fome reafon for it in the nature of things. Find- ing that it gave him very neat folations of many ele- mentary problems in dynamics, he thought of trying whether 11 would affift him in accounting for the con- ftant ratio of the fines of incidence and rcfraftion ; he found that it gave an immediate and very neat folution. This problem had, before his time, occupied the minds of Des Cartes and Fermat. Each of thefe gentlemen folved the problem b-y iaying, that the light did not take the Jburhfi way from a point in the air to a point under water, but the f(7//f/? way, in conformity with the acknowledged economy of nature and confummate wif- dom of its adorable Author. But how was this the eafieft way, the courfe that economifed the labour of nature ? One of thefe gentlemen proved it to be fo, if light move fafter in air than in water ; the other pro- ved it to be fo, if light move fafter in water than in air. Both could not be right. Maupertuis was convinced that he had difcovered what it was that nature was fo chary of, and grudged to wafte — it was MVS! There- fore MVS can mean nothing but labour ; nothing but natural exertion, mechanical aftioif ; therefore MVS is the proper m'eafure of aftion. 'He kept this great dif- covery a profound fecret ; and, being Prefident of the Royal Academy of Berlin, he propofed for the annual prize queftiou, " Are the laws of motion necefTary or contingent truths ?" He could not compete for the M I C S. 547 prizei by the Uw8 of the Academy ; but before tbeCnnduCmn. time of decillon, he publilhed at Paris his Di^'itat'ion on » the Principle of the lenjl ASion; in which he pointed out the fmgular taft of MVS being always a minimum; and theretorc, in tart, theobjeft of nature's economical care. He folved a number ol problems by making the mini. mum flate of < a condition of the iiroblems ; and, »; to crown the whole, fhewed that the laws of motion which obtain in the univerfo could not be but whit they are, bec;nife this economy was worthy of infinite wifdom ; and thenj'ure any other laws were impoffible. The reputation of Maupertuis was already ettabliflied as a good matliematician and a worthy and amiable man, and he was a favourite of Frederic. The princi- ple of ieaft aiftion became a mode ; and it drew atten- tion for fome time, till it went out of fafliion. It is no mechanical principle, but a ncceffary mathematical truth, as any perfon muft fee who recollerts that -u is the fame with s, and thatyis the fame with in i). To avoid fuch paralogifms and fucli whims, we are Great ad- convinced that it is prudent to deviate as little as pof-^^n^ges of fible in our difcufiions from the geometrical method. .^ K^°"'^' This has furely the advantage of keeping the real fub-,}jod. jeft of difcuflion clofe in view ; for motion includes the notion of lines, with all their qualities of magnitude and pofitlon. It is needlcfs to take a reprefcntative when the original itfelf is in our hands, and affords a much more comprehenfible objefl than one of its ab- ftraft qualities, mere magnitude. Let any perfon can- didly compare the lunar theory by Mayer or Euler with that by its illuilrious inventor Sir Ifaac Newton, and fay which of the two is mofl luminous and moit pleafing to the mind. No perfon will deny that thefe later performances are incomparably more adapted to all prartical purpofes, and lead to corredliona which it would be extremely difficult and tedious to inveftigate geometrically ; but it mull be acknowledged, at the fame time, that till this be done, we have no idea what- ever of the deviation of the track which this correftion afcertains from the path which the moon would follow, independent of the difturbaucc exprcded by the cor- rertiou. In like manner, Dan. Bernoulli, by mixing as much as pofTible the linear method with the algebraic, in his differtations on mufical chords, made the beauti- ful difcovery of the fecondary trochoids, and demon- ftratcd the co-exillence of the harmonic founds in a full mufical note. Let the accomplilhed mathematician pufh forward our knowledge of dynamics by the employment of the fymbolical analyfis ; but let him be followed a> clofe as polFible by the geometer, that we may not be robbed of ideas, and that the ftudent may have light to direft his lleps. But, — manum e taluld. ■«w*rsRfs^ nano- eter. D Y N DYNANOMETER, an inftrument for afcertaining the relative mufcular ftrength of men and other animals. That It would be defirable to know our relative ftrengths at the different periods of life, and in different ftatcs of health, will hardly be denied ; and there can be no doubt but that It would be highly ufcful to have a portable Inftrument by which we could afcertain the lehtive ftrength of horfes or oxen intended for the D Y N plough or the waggon. Such an inftrument was invent- ed, many years ago, by Graham, and improved l>y De- faguliers; but being conftruCted of wooden work it was too bulky to be portable, aud therefore it was limited in Its ufe. M. Leroy of the Academy of Sciences at Paris con- ftrudled a much more convenient Dynanometer than Graham's, confiding of a metal tube, 10 or 12 inches 3 Z 2 in D Y S [ 548 ] D Y S . iti length, placed vertreally on a foot like that of a can- horfes or oxen may be employed to comprcfs the fpring. rij- dltilick, and containlnjr in the infide a fpii'al I'pn'ng, But as any mechanic may devlfe means for this purpofe, '~ having above it a graduated ihank terminating in a we do not think it worth while to tranfciibe that de- globe. This fhank, together with the fpring, fniik into fcription. The Englifh reader will find a full account th'e tube in proportion to the weight aiSing upon it, of the whole apparatus in the 4th number ot the very and thus pointed in degrees tlie llicngth of the perfon valuable mifcellany intitled The Ph'dofoplncal Magazine. ■who pveiTeJ on the b?.ll with his hnnd. The principle of the contrivance confills in the ellipti- This was a very fimple conllruflion, and, we think, cal fpring, of which we confcfs ourftlves unable to per- a good one; but it did not fatisfy Buffon and Gueneau. ceive the fuperiority to the fpiral fpring of M. Lf. oy, fentei de I* EcMe Polytrcb- ni^ue^ V. a. Thefe two philofophcrs wi(hed not merely to afcertain the mufcular force of a finger or a hand, but to efti- mate that of each limb feparately, and of all the parts of the body. They therefore employed M. Regnier to contrive a new dynanometer ; and the account which he gives* of his attempts to fulfil their wifhes is calcu- lated to enhance the difficulty of the enterprize. The though the author fees it very clearly. DYSENTERY. See MEDiciNE-/n^/«, Encycl.— For the cure of tliis difeafe we have tiie following finipk prefcription by Dr Perkins and Dr B. Lynde Oliver, of the State of Malfachufetts in North America. Saturate any quantity of the beft vinegar with com- mon marine fait; to one large table-fpoonful of this fo- inftrument, however, which he conftrufted, is not futh lution add four times the quantity of boiling water; let as appears to us to have required any uncommon ilvill the patient take of this preparation, as hot as it can be In mechanics, or any very great ftretch of thought. It fvvallowedy one fpoonfu! oace in half a minute until the confills chiefly of an elh'ptical fpring, 12 inches in whole is drank : this for an adult. The quantity may length, rather narrow, and covered with leather that it be varied according to the age, fize, and eonlUtution of may not hurt the fingers when compreiTed by the hands, the patient. If neceffary, repeat the dole once in fix or This fpring is compofed of the btft fttel well welded and tempered, and afterwards fubjefted to a fti onger effort than is likely to be ever applied to it either by men or animals, that it may not lofe any of its elalli- city by-ufe. The effefts of this machine are eafily explained. If ecglit liours. Confiderable evacuations I conceive (fays Dr Parkins) to be _not only unneccffary, but injurious, as they ferve to debilitate and prolong the dileafe. A tea of plantain, or fome other cooling fimple drink, may be ufeful; and if a thirft for cyder be difcovered, it may be gratified. Carefully avoid keeping this preparation a perfon compreflfes the fprmg with his hands, or draws in vcflels partaking of the qualities of lead or copper, as it out lengthwiCe by pulling the two extremities in con- ''- "'" J-- J l- .1 - -«••<. .1 - trary direftions, the fides of the fpring approach towards each other; and it has an apparatus (we do not think a very fimple one) appended to it, confifting of an in- dex and femicircular plate, by which the degree of ap- proach, and confequently of effort, employed, is afcer- tained with great accuracy. The author gives a tedi- ous defcription of other appendages, by means of which the poifon produced by that means may prove dangerous. The fuccefs of the remedy depends much on prepa- ring and giving the dole as above direfted. — The fim- plicity of this treatment renders it the more valuable, as all perfons have it in their power to avail themfclvts of its life. Dr Perkins fays, that he has found it ufeful in agues, diarrhosas, and the yellow fever. E. larih. EAR EARTH, in chemiftry. See CHEMISTRY-Zwifw in this Supplement. Earth, in aftronomy and geography. See Encydo- picdia. Earth, in ancient philofophy, one of the elements, the fubftance of which this globe is compofed. To af- certain the denfity of that fubftance, many experiments have been made; but perhaps none more ingenious than thofe of Mr Caveudilh, which are detailed at full length in Part II. of the Tranfaftions of the Royal Society of London for 1798. They were projefted by the late Rev. John Michell, F. R. S. but he did not live to carry them into effei^. After his death, the apparatus came to the Rev. F. J. H. Wollafton, Jaekfonian Pro- feffor at Cambridge,- who transferred them to Mr Ca- vendidi. The apparatus contrived for making fenfible the attraftion of fmall quantities of matter, and which has been improved by Mr Cavendilh, is very fimple : it EAR confifts of a wooden arm 6 feet long, fufpcnded by the middle in an horizontal pofition by a flender wire 40 '■ inches long ; to eagh extremity is hung a leaden ball about two inches in diameter; and the whole is inclofed in a wooden cafe to defend it from the wind. As no more force is required to turn this balance on its centre t^an is neceffary to twifl the flender fufpend- ing wire, the fmallcfl degree of altraftion of a leaden weight or weights, a few (eight) inches in diameter, brought near to the fmall fufpended ball or balls of the balance, will be fufEcient to move it fenfibly afide. To determine from hence the denfity of the earth, all that is neceffary is, to afcertain what force is required to draw the arm afide through a given fpace, and then to have recourfe to calculation. To prevent any difturbance from currents that might be produced within the box that contained the balance, by even the difference of temperature that might be oc- cafioned 1 ))■. voi; oMr, T r. 1! . i'f.atk wt. rk-.i. ^So.= I:"i!^2. -"r <■' •?'■ K Fi..,.7.y;Jx, ?^~-^. l^i'V-7- I) Fig. 2.' r r \ .rY p/ \ c / \j -y/ l)^^■.\^rI^ s. ri,.\ri. vxil. \ .V / H, \ /• /• \ DY]srA:5 \ ;P ■V. ^ u \ ■•• /" /"\ y / \ ^ / I l> \l v^ -? y^ ^-^ — \ \ / i" ^ ^^^^_ Y, G\ p- ,,.;f. '■?' ' K 7\ \\ A\ \ / \ \ ■"^ z V "* liii'iTp'''''^ fy^^Tll 1 n 'iifi 1 f i ■!' i ' ' L i^! :l:l .1 1| i l>»7,^"■/.fl•.^• .l',-iW,<; Eaith. EAR [ 549 ] E A U cafioncd by heat being communicated by tlic bodies of lent lymptoms of great uncafinefs. If this liquor be ' the experimenters to one fide of it more than another, poured into thofe holes in which the earth-worms refide it was fupported in the middle of a clofe room; the underground, they immediately throw thcmfelves out operators, from adjoining ajiartments, viewed the ope- as if driven by fomc force ; and, after various contor ration through holes in the wall by means of telefcopes; tioiiG, either languilh or die. If the leaves of plants or and the apparatus had a Ihong light thrown upon its fruit trees frequented by the voracious caterpillars, two ends (an opening being left at each end of the box which are lo dellructive to tliem, be fprinkled over with for the purpofe) by means of two lamps, alfo in the ad- this liquor, thefe iiifeds fuddenly cortraft their !)odie» joining apartments, the rays from which were likewile and drop to the ground. For tiiough Nature has de. made to pafs through the holes formed in the wall. fended them tolerably well by tlicir hairy (kins from The two large balls were fufpended from a beam any thing that might injure their delicate bodies, yet as near the cieling, which could be moved in an hori. foon as they touch witli their feet or mouths leaves zontal dircdtion, by means of a firing and pulley, fo which have been moiilened by this liquor, they become as to be brought near to the fmall balls of the balance, as if it were ftupified, inllantly contraft themfelves, and or made to recede again, without requiring any perfou fall down. to be in the room. With regard to plants or corn, thcfe fuiiain no inju- rVom this dcfcrlption it will be eafily fetn, that on ry from the liquor, .becaule it has no power over the the two large balls being brought near to the two fmall produftions of the vegetable kingdom, as our author ones, but on oppofite fides of each, tliat their forces has fully learned from experience ; or if any hurt is to way not counteraft each other — the fmall fufpending be fufpedled, all the danger will be removed by the firft wive of the balance muft; be twilled by the movements fhower that falls. This liquor may be procured. In a- of the arms, occahoned by attraction, which carries the bundance in every place where lime is burnt. ,If the fmall towards the large balls ; and that the wire, cndea- lime be frefli, one part of it infufed into about feventy vouring to untwift itielf, will again in its turn carry the parts of common water will produce real lime-water, fmall balls away from the large ones. Vibrations are The want of the fixed alkali may be fupplied by boil- thus occafioned, which would continue a long time be- ing wood-alhes m water, and thickening the ley by fore the fmall balls would fettle between the tirll point evaporation. of relt and the large balls : but it is not neceffary to 1'his liquor might be employed alfo to kill bugs and wait for this; an ivory fcale at each end of the balance other domeftic inieifts ; but on account of its tlrong enables the experimenters, by means of their telefcopes, lixivious fmcll, M. Socoloff thinks it could not be ufed to fee the two extreme divifions to which the fmall balls with fafety in houfes that are inhabited. Nothing, how- move in their vibrations, and thus to determine tlie ever, more fpeedily or more effcftually deflroys bugs, middle point. The time necelfery for each vibration is as our author lays he has repeatedly experienced, than alfo noticed. the oily pickle that remains in cafks in which faked A full account of thefe experiments, and of the cal- herrings have been packed Earth, Hai delucti culations founded on them, would be little interelling to the great majority of our readers. We (hall there, lore only mention the refult. By a mean of the expe- riments the dcnfity of the earth comes out 5 '48 times greater than that of water. EAU DE Luce, a fragrant alkaline liquor which was fome years sgo in great repute, efpecially among the fair fex, and of which the leading perfection is, that it fhall pofTcfs and retain a milky opacity. Mr Nicholfon, in the fecond number of his valuable By the experiments made by Dr Ma(l cauftic volatile alkali were then poured in, and imme- thor that this mixture would be the beft means for ac- diatcly fhaken. The fluid was of a denfe opake white complifliing the objedl which he had in view. He colour, affording a flight ruddy tinge when the light therefore took three pai-ts of quicklime, newly made, was feen through a thin portion of it. In a fecund and two parts of a faturated folution of fixed alkali in mixture,, tour parts of the alkali were added to one uf water, and thence obtained a foniewhat milky liquor the folution of maflic ; it appeared of a lefs denfe and fuiEciently cauftic, highly hoflile and puifonous to earth- more yellowifii white than the former mixture. More- wot ms and other fmall animals; for as foon as it touch- of the gum rcfinous folution was then poured in ; but it. «:d any part of their bodies, it occafioned in them vio. ftiil appeared Icfs opaque lliau tlmt misture. It was fjddj E C L r SS l'5\i