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CHEMICAL AND PHARMACEUTIC 
 
 MANIPULATIONS. 
 
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CHEMICAL AND PHARMACEUTIC 
 
 MANIPULATIONS: 
 
 A MANUAL OF THE MECHANICAL AND CHEMICO-MECHANICAL 
 » OPERATIONS OF THE LABORATORY, 
 
 CONTAINING 
 
 A COMPLETE DESCR^TION OF THE MOST APPROVED APPARATUS, WITH 
 
 INSTRUCTIONS AS TO THEIR APPLICATION AND 
 
 MANAGEMENT BOTH IN 
 
 MANUFACTURING PJIOCESSES, 
 
 AND IN THE MORE EXACT DETAILS *0F 
 
 ANALYSIS AND ACCURATE RESEARCH. - 
 
 FO^ THE USE OP CHEMISTS, DRUGGISTS, TEACHERS AND STUDENTS. 
 
 BY 
 
 CAMPBELL M^O REIT, 
 
 PRACTICAL AND ANALYTIC CHEMIST, AUTHOR ^F "APPLIED CHEMISTRY," ETC. 
 
 ASSISTED BY 
 ALEXANDER MUCKL6, 
 
 CHEMICAL ASSISTANT IN PROFESSOR BOOTH'S LABORATORY. 
 
 WITH FOUR HUNDRED AND TWENTY-THREE ILLUSTRATIONS. 
 
 1^ 
 
 PHILADELPHIA: 
 
 LINDSAY AND BLAKISTON, 
 1849. 
 
 
"The Hou»e tUat Jauk BuUt.'» 
 
 One of the beat travesties on the old nursery tal^ 
 
 the full iwirig froGa au exchange: _ 
 
 he White House— This is the house thHi'Samj 
 
 built. . ■ "!i>^v^ '■■ .■ . i; '^■ 
 
 LOO. OUO -This is the malt that lay m t^ehoaee 
 
 thut S^mhuilt. ' • v. '■'- 
 
 ames Buchan^u— This is the rat that ate the malt, 
 
 thai lay iu the house tliat Sam built: 
 . A. Douglas— Thw is the cat thnt killed the rat. 
 
 that Hte the malt, that lay in the house that 
 
 Sara t'uih. . 
 
 ireckiiiridpe— This is the dog, that worried the 
 
 cat, that killed the rat, that ate the malt,.thftt; 
 
 lay iu ihe house th it Sam biiilt. 
 lell-Bverett— rhia is the c )w with the crumpled 
 
 horn, that tossed the d.-g, that worried the 
 
 cat, et'% 
 fewYoik Bxrreps— This is the maiden, all forn 
 
 lorn, that mi.ked the cow with the crumpled 
 
 horn, that, etc. 
 ournal of Commerce— This is the man, all tat- 
 tered and torn, that kissed the itaiden, all 
 
 forlorn, that, etc. 
 Jew York Onserver— This is the prie«t, a!F shaven 
 
 and shoru, that married the man, all fntterod 
 
 arjd t fTQ, unto 'he aiaid^n all for 
 ndependent— Tliis i- the cock that r 
 
 morn, to waken the priest mI' :; _:_ 
 
 shorn, that married them- td aud 
 
 torn, etc. . ■ ^ 
 
 Lbe Lincohi— This is the hun- • --.-,* 
 
 and imin, that owned the • 
 
 the morn, to waken the pri' 
 
 shorn, I hit m lined the m.i 
 
 torn, uuu) ihe maiden all t 
 
 the cow witii a crumbled li 
 
 dog, that w. rried the cat, 
 
 that ate the malt, that la} 
 
 Sam huilt. 
 
 I. B,*a Farewell to tl&« lV||^lte House. 
 
 I^arewell to the land where tihe gloom of my glory. 
 Arose and o'ershaduwed the earth with her 
 name ; 
 }he abandous me now, but the page of her story, 
 
 The foulest aud blackest, Uflil'd with my shame. 
 ! have war'd with the Yankees, who vanquished 
 me only 
 When th-. scent of the " da;\ . d to his 
 
 lair ; 
 [have coped with the free who dt^iii-c me'*ihu8 
 loMe'y, 
 The last tiaJtorous " Doughface" who'll sit in 
 this chair. Jf. 
 
 OUR PUBLIC SCHOOLS. 
 
 [The following beautiful song, by Mrs. C. H. 
 GiLDERSLEEVE, was sung at the late Teachers' 
 Convention at Buffalo.] 
 
 A song, a song for public schools, 
 
 Our people's proudest glory, 
 And while we sing, the nation's stars 
 
 Grow brighter at the story, • 
 And lighter float those restless folds. 
 
 And higher still we follow; 
 And scorn a name whose only sound, 
 
 Like ringing gold, is hollow. 
 
 Then free as air shall. kflowl edge be, 
 
 And open window's portals, 
 To every thirsty, earnest soul, 
 
 Who longs to be immortal. 
 Here rich and poor stand side by side 
 
 To quaff her poorest chalice, 
 And neverdream that deathless names 
 
 Belong to cot or palace. 
 
 The light of truth shall guide us on, 
 
 When glory lies before us, 
 And "Right makes Might" emblazoned on 
 '' The banner waving oe'r us. 
 iA song, a loud, exultant song 
 
 Shall ring from sea to prairie, 
 And tell the world that mikd not gold, 
 
 Shall make our stations vary. 
 
 Lincoln's Majoeity,,in New .Yobk.— Thej 
 Tribune of the 12th foots up Lincoln's majopv^ 
 ty in that State about 51,777. The rural dis-' 
 trlcls loom up. St. Lawrence Co. gives 7,214 
 Republican mnjority ! j 
 
 MARRIED. 
 
 On January 3rd, 1861, by Rev. S. Searls 
 at the residence of the bride's father, in Dart- 
 ford, Dr. H. L. Baenes and Miss Nelly E. 
 Cody, all of Dartford, Wis. 
 
 LAnELPHIA : 
 
 J. COLLINS, PRINTERS. 
 
BY OLIVEE WENDELL HOLMES. 
 
 6? 2)6/ 
 
 A184 
 
 /849 
 
 3 count the broken lyrevS that rest, 
 
 Where the sweet wailing singers slumber, 
 
 it o'er their silent sister's breast 
 
 rbe wild flowers who will stop to number ? 
 
 few can touch the magic string, 
 
 (Vnd noisy Fame is proud to win them ; 
 
 IS ! for those that never sing; 
 
 3ut die with all their music in them ! 
 
 y, grieve not for the dead alone 
 
 ^' hose song has told their heart's sad story- 
 
 ep for the voiceless, who have known 
 
 >ie cross witiii>ut the crown of glory ! . 
 
 where Leucadian breezes sweep 
 >'er Sappho's memory-haaoted pillow, I ' 
 
 where the glistening night-dews weep 
 
 ''er nameless sorrow's church yard pillow, ^. #. i i -i ^ ^^ .- 
 
 •^ V^ stic 01 modern philosophy, — distin- 
 
 learts that break and give-np^slsn ^ j^t system, the futility of which is 
 
 I ve whitening lips and fading tresses, L , . ■■ . i • 
 
 Death pours out his cordial wine. [;ses_pstract speculations upon whlch it 
 
 ow-dropped from Misery's crushing pres. -3 principles are Supported by facts 
 
 nging breath or echoing chord 
 
 ) every hidden pang w^re given, ' ' ^ 
 
 EFACE. 
 
 riment. 
 
 t endless melodies were poured, 
 i sad as earthy as sweet as heaven ! 
 
 f reasoning, which has led to gi- 
 parted to chemistry all its consist- 
 ' ^nue, ife'thfe'Oril^r'Siire way of .pursuing investigation, for it is 
 by conclusions, and not hypotheses, that we can show the com- 
 position of bodies, or the principles which govern their re- 
 actions. 
 
 To realize, therefore, for chemistry the simple definition of 
 a science, — to render it "a system illustrated and proved by 
 experiment," it is requisite for us to acquire some proficiency 
 in those mechanical operations by means of which chemical 
 changes are produced, observed and estimated. 
 
 This accomplishment in manipulation, — this expertness in 
 handling implements, it is true, demands practice and expe- 
 rience ; but though the student cannot become an adept in the 
 art solely by the aid of written directions, yet much may be 
 communicated which will lighten labor and facilitate him in 
 the attainment of skill and accuracy. 
 
 ^41^0 
 
VI PREFACE. 
 
 Such has been the author's object in preparing the present 
 work, which in its arrangement is designed to lead the unin- 
 itiated step by step into the mysteries of manipulations; and 
 in which he has endeavored with less regard to elegance of ' 
 diction than to perspicuity, to present plainly and clearly 
 such information as is best calculated to give familiarity with 
 the construction, arrangement and uses of apparatus. 
 
 Positive originality can scarcely be expected in any ac- 
 count of the well known appliances of the chemical art. The 
 author has, however, while availing himself freely of the 
 knowledge of others, endeavored to combine with it, as much 
 as possible, personal experience, and to present descriptions 
 of new and important forms of apparatus, with practical 
 suggestions of a novel character. 
 
 In confessing indebtedness to other chemists, the author 
 acknowledges his obligations to Prof. J. B. Reynolds for the 
 whole of the chapter upon "Analysis by Polarization of 
 Light," a subject which the writer's skill and experience 
 have well qualified him to illustrate. 
 
CONTENTS. Xlll 
 
 CHAPTER XXVII. 
 
 BLOWPIPE MAWIPULATipir. 
 
 Use and construction of blowpipes. Wollaston's, Gahn's, Mitscherlich's 
 blowpipes. Economical blowpipe. Blowpipe lamp and appliances. 
 Flame. The mode of holding the blowpipe : — the blast ; — the supports. 
 Detection of volatile substances by means of the blowpipe. Instruments 
 used in analyses by the blowpipe. Reagents. Blowpipe table. The 
 test series . . . . . . . . 367 
 
 CHAPTER XXVIII. 
 
 AlfALTSIS OF SACCHAHINE SUBSTANCES BY PGLARTZATIOTT OF LIGHT. 
 
 The polarizer and analyzer ; — circular polarization. Ventzke's apparatus. 
 Method of analyzing sugars. Decolorization of colored solutions. Soleil's 
 saccharimeter. Clerget's method. Table for the analysis of saccharine 
 substances . . . . . . . .391 
 
 CHAPTER XXX. 
 
 ELECTRICITY. 
 
 Electrical machines 5 Leyden jar ; — electrical battery ; — discharger. The 
 electrophorus. Detection and measurement of . electricity ; — Henly's 
 quadrant electrometer ; — Bennet's and Coulomb's electrometers. Appli- 
 cations of electricity: — eudiometry; — Ure's eudiometer. Galvanism. 
 Wollaston's, Daniell's, Smee's, Grove's, and Bunsen's batteries : — con- 
 nection of batteries. Electrolysis. Production of heat and light by gal- 
 vanism. Hare's sliding rod eudiometer and calorimotor. The means 
 of detecting galvanic fluid ; — the galvanometer. Astatic galvanometer . 409 
 
 CHAPTER XXXI. 
 
 CONSTRUCTION OF FORMULA . . . 452 
 
XIV CONTENTS. 
 
 CHAPTER XXXII. 
 
 GLASS-BLOWIJfG. 
 
 Blowpipe table and lamp: — Implements. Cutting of glass. Tubes 
 cemented, bent, drawn out, and closed. Lateral attachments. Bulbs 
 blown. Welter's and funnel tubes fashioned . . . .455 
 
 CHAPTER XXXni. 
 
 CORKS. 
 
 Corks softened, — perforated. Cork borer ..... 466 
 
 CHAPTER XXXIV. 
 dealehs in and manufacturers of apparatus . . 468 
 
^^s 
 
 
 
THE LABORATORY. 
 
 CHAPTER I. 
 
 The Laboratory is emphatically the work-shop of the che- 
 mical operative ; and chemical manipulation may be termed 
 the practice of the science. A convenient arrangement of 
 the first is no less desirable, for the success of operations, than 
 a proficiency and skill in the latter is indispensable. New 
 facts in science are mainly developed by experiment ; and as 
 chemistry is a purely experimental science, in every course of 
 research, as well in the most ordinary experiments as in the 
 more delicate manipulations of analyses, the surest basis of 
 accurate conclusions is an exact and skilful manipulation 
 coupled with correct reasoning. This exemplification, by 
 the hands, of the conceptions of the mind, is, therefore, an 
 art of the highest importance in the pursuit of chemistry. 
 
 The laboratory should be appropriately fitted, and arranged 
 with a view to the easy prosecution of chemical investiga- 
 tion in all its several branches ; and being the place where 
 most of the operator's time is so profitably and pleasantly 
 employed, no little regard, in its appointments, should also 
 be given to personal comfort and convenience. We do not 
 recommend extravagance in its furniture and paraphernalia, 
 or yet a too rigid economy, for though a stinted apparatus 
 '^^y? hy ingenuity and skill, be rendered subservient to the 
 requirements of the science, a liberal endowment is far pre- 
 ferable, and more conducive to rapidity of progress and accu- 
 racy of results. In the present advanced state of the mechanic 
 arts, it is doubtful economy to consume time in constructing 
 contrivances, when the most convenient apparatus may be 
 readily procured at the lowest rates. Moreover, a familiarity 
 with the use of good tools originates habits of correct and 
 3 
 
56 LIGHT — VENTILATION. 
 
 delicate manipulation, and will afford, to the experimenter, 
 a proficiency enabling him, in any emergency, to substitute 
 available material for deficient apparatus; whilst in working 
 upon rare substances, the minutest quantity will be no bar to 
 his skill and accuracy in bringing out nice results. 
 
 We do not, in the following suggestions, provide for such a 
 laboratory as is suitable for a public institution, because the 
 adaptation of one of that extent would be attended with an 
 expense inconsistent with individual means, as there are many 
 auxiliaries required in class experiments which may readily be 
 dispensed with in an ordinary laboratory; but, we present an 
 apartment economically and conveniently arranged for private 
 research, with space and furniture enough, with some slight 
 multiplication of the apparatus, for two, four, or more ex- 
 perimenters. 
 
 In the construction of a laboratory, particular attention 
 should be paid to the lighting and ventilation of the apartments, 
 both in regard to the health and comfort of its occupants. 
 The preferable mode of lighting is by side windows, and for 
 many reasons; it is more advantageous in examining the 
 behavior of re-agents to solution, especially in those instances 
 of delicate testing, where the result is determinable by the form- 
 ation of flocculae, faint cloudiness, or by slight transmutation 
 of color. By elongating the windows to nearly the whole height 
 of the apartment, we obtain the magic influence of the solar 
 rays, now known to be so effective in inducing chemical 
 changes unattainable by other means. The skylight arrange- 
 ment has the double disadvantage of presenting nuclei for the 
 accumulation of dust, and being subject to frequent breaches 
 by accident or storm. Ventilation may be accomplished 
 thoroughly by means of counterpoised windows and stationary 
 hoods. 
 
 The laboratory apartment should be sufficiently spacious 
 to afford a separate position for each of the requisite utensils. 
 Too much crowding of apparatus engenders liability of damage, 
 and is, besides, inconvenient, for nowhere than in a laboratory 
 is there more necessity of a strict observance of the rule, "a 
 jplace for everything ^ and everything in its place.'' Hunting 
 up mislaid apparatus consumes time, and the delay thus oc- 
 casioned, in many instances, may be the means of serious 
 detriment to important operations. 
 
 A roomy apartment on the first floor of a building is best 
 
-VS-fjiv^-iiSSiip., 
 
 .■•x»:*»*i»w*- 
 
 ^t'K^toaJC 
 
 ':^!^^^^'^mw^mm 
 
THE FURNACE. 35 
 
 ratus, to keep the side door i (7 feet high, and 2.10 wide) lead- 
 ing into the main apartment constantly closed. The front of 
 this wing is, as to windows, identical with that of the office. 
 The free admission of light, which is effected by means of the 
 two long front and three elevated side windows, is as requisite 
 in this as in the operating room. The chimney of this apart- 
 ment occupies the centre of the outer wall, and receives the 
 main flue, furnishing draft to the main furnace and two late- 
 ral branches. Of these two branch flues, both of which have 
 circular openings with movable tin stopples, one is for the 
 reception of the smoke-pipe of the still furnace E, and the other 
 for that of the steam generator F ; or, when not in use other- 
 wise, for the portable, blast, and other furnaces. These flues 
 are fitted with dampers to regulate the draught; and the cir- 
 cular opening, when not occupied with apparatus, or as vent 
 holes for the dispersion of noxious vapors, should be kept co- 
 vered so as to preserve unimpaired the draught of the main 
 furnace. In the arrangement of a room, for laboratory pur- 
 poses, wherein the flues are not convenient, they must be sub- 
 stituted by stove-pipes. 
 
 The Furnace. — The furnace Gr, which is in constant use for 
 the ordinary operations of the laboratory, occupies the centre 
 of the outer wall. That of most convenient construction is 
 described by Faraday, to whom we are indebted for both our 
 description and figures. 
 
 "Being in constant requisition as a table, it should be about 
 34 or 35 inches in height. The brick work should measure 
 36 by 20 inches, and the iron plate, including sand-baths, 40 
 by 28 inches. A warm air chamber may be built in the walls 
 beneath the flue. Projecting spikes should be fastened into 
 one or two sides of this chamber, to hold a temporary shelf 
 when required. 
 
 "Precipitates, filters, and other moist substances put into 
 such a chamber, are readily and safely dried. The hot air 
 causes evaporation of the water, whilst the current removes 
 the rising vapor. The chamber is very useful in effecting the 
 slow evaporation of liquids, and also for hot filtrations, when 
 the entering current of air is of a temperature sufficient for 
 the purpose. 
 
 "The principal part of this furnace is necessarily of brick- 
 work, only the top plate with the baths and the front, being 
 of iron. The front is a curved iron plate, having two aper- 
 tures closed by iron doors, one belonging to the fire-place, and 
 
THE FURXACE. 
 
 Fig. 6. 
 
 the other to the ash-pit. It is 34 inches high, and 14 inches 
 wide. The ash-hole door moves over the flooring beneath ; 
 
 the bottom of the fire-place 
 door is 22 inches from the 
 ground, and the door itself 
 is 8 J inches bj 7. This front 
 is guarded within at the part 
 which encloses the fire by a 
 strong cast-iron plate, having 
 an opening through it corre- 
 sponding to the door of the 
 fire-place. It has clamps 
 attached to it, which, when 
 the furnace is built up, are 
 enclosed in the brick-work. 
 In the setting or building of the furnace, two lateral brick 
 walls arc raised on each side the front plate, and a back wall 
 at such a distance from it as to leave space for the ash-hole 
 and fire-place ; these walls are lined with Welch lumps, where 
 they form the fire-chamber; two iron bars are inserted in the 
 course of the work to support the loose grate bars in the usual 
 manner, the grate being raised 19 inches from the ground. 
 The side walls are continued until of the height of the front, 
 and are carried backward from the front in two parallel lines, 
 so as to afford support for the iron plate which is to cover the 
 whole. The back wall of the fire-place is not raised so high 
 as the side walls by six inches and a half, the interval which 
 is left between it and the bottom of the sand-bath, being the 
 commencement of the flue or throat of the furnace. In this 
 way the fire-place, which is fourteen inches from back to front, 
 and nine inches wide, is formed, and also the two sides of the 
 portion of horizontal flue which belongs to the furnace, and 
 is intended to heat the larger sand-bath. The bottom of this 
 part of the flue may be made of brick- work, resting upon bear- 
 ers laid on the two side walls, or it may be a plate of cast-iron 
 resting upon a ledge of the brick-work on each side, and on 
 the top of the wall, which forms the back of the fire-place. 
 When such an arrangement is adopted, the plate must not be 
 built into the brick-word, but suffered to lie on the ledges, 
 which are to be made flat and true for the purpose ; for, if 
 attached to the walls, it will, by alternate expansion and con- 
 traction, disturb and throw them down. The ends of the side 
 
THE FURNACE. 
 
 87 
 
 walls, forming as it were the back of the furnace, may be 
 finished either by being carried to the wall against which the 
 furnace is built, or enclosed by a piece of connecting brick- 
 work, to make the whole square and complete, or a warm air 
 cupboard may be built in the cavity beneath the flue, and the 
 door made to occupy the opening between the walls. Occa- 
 sionally the flue may be required to descend there, and pass 
 some distance under ground. These points should be arranged 
 and prepared before the plate constituting the top of the fur- 
 nace is put on to the brick-work, so that when the plate with 
 its sand-baths are in their places, they may complete the por- 
 tion of horizontal flue by forming its upper side. 
 
 The size of this plate is the first thing to be considered, and 
 having been determined upon, from a consideration of the 
 situation to be occupied by the furnace, and the places of the 
 sand-baths also having been arranged; the brick-work must 
 then be carried up, so as to correspond with these determina- 
 tions, and with the plate itself, which in the mean time is to 
 be cast. The sand-baths and the plate are to be formed in 
 separate pieces. The bath over the fire is best of a circular 
 form, and of such diameter that, when lifted out of its place, 
 it may leave an aperture in the plate equal in width to the 
 upper part of the fire-place beneath ; so that a still, or 
 cast-iron pot, or a set of rings may be put into its place over 
 the fire. The other sand-bath must be of such a form as to 
 correspond with the shape and size of the flue beneath. These 
 vessels are to be of cast-iron, about three-tenths of an inch 
 thick; their depth is to be 
 two inches and a half or ^^* ' 
 
 three inches, and they are 
 to be cast with flanches, so 
 as to rest in the correspond- 
 ing depressions of the plate 
 that the level of the junc- 
 tions may be uniform. This 
 will be understood from the 
 accompanying section of the 
 furnace, given through the 
 line AB of the view. It is essential that these sand-baths 
 be of such dimensions as to fit very loosely into the apertures 
 in the plate, when cold, a space of the eighth of an inch or 
 more being feft all round them, as shown in the section, other- 
 
38 
 
 THE FURNACE — THE SAND BATHS. 
 
 wise, when heated, they will expand so much as entirely to 
 fill the apertures, and even break the plate. The plate itself 
 should be half an inch thick. 
 
 When the plate and its sand-baths are prepared, and the 
 brick-work is ready, the furnace is finished by laying the plate 
 on the brick-work, with a bed of mortar intervening. If the 
 walls are thin, or any peculiarity in their arrangement occa- 
 sions weakness, they should be bound together, within by 
 cranks built into the work, and without by iron bands.* The 
 alternate changes of temperature from high to low, and low 
 to high, to which the furnace is constantly subject, renders it 
 liable to mechanical injury, in a degree much surpassing that 
 which would occur to a similar piece of brick-work, always 
 retained nearly at one temperature." The square space en- 
 closed by the fire-place and flues may be converted into ail 
 excellent drying or warm air chamber if desired. 
 
 Cast-iron is the best material for these baths, for, though 
 liable to be cracked when first heated, by their unequal ex- 
 pansion in diff*erent parts, they do not warp and assume the 
 irregular and inconvenient shapes that wrought iron acquires 
 under similar circumstances. 
 
 " These baths should have washed sea-sand put into them ; it 
 is heavy, and occasions no dust when moved, whilst, on the 
 contrary, unwashed and bad sand contains much dirt, and 
 occasions great injury in experimenting. A piece of straight- 
 ened iron hoop, about twelve inches in length, should lie on 
 the furnace, as an accompaniment to the baths, being a sort of 
 coarse spatula with which to move away the sand. 
 
 The circular sand-bath is frequently replaced by a set of 
 concentric iron rings, or a cast-iron 
 pot. The rings are convenient for 
 leaving an aperture over the fire of 
 larger or smaller dimension, according 
 as a smaller or larger number are used 
 at once; and being bevelled at the 
 edges, fit accurately into each other, 
 without any risk of becoming fixed by 
 expansion. The external one, like the 
 sand-baths, should be made smaller 
 than the depression in the furnace 
 plate in which it rests. The iron pots 
 are of various sizes, and are adapted 
 
 Fig. 8. 
 
THE FURNACE — THE SAND BATHS. 39 
 
 to the furnace by means of the rings ; a red heat is easily 
 obtained in them for sublimation." 
 
 In m^ny instances, where economy is of prime importance, 
 the foregoing sand-bath can in a measure be substituted by 
 an ordinary cylinder stove, the pipe of which leading into 
 a four sided sheet iron box, divided into flues by par- 
 titions, imparts its heat which eventually passes into the 
 chimney. The top of this box when covered with sand, forms 
 the sand-bath. That portion of its surface immediately over 
 the first flue, is the hottest. The remote or cooler end, is best 
 adapted for gradual digestions, evaporations, &c.; and so by 
 these flues there is a means of graduating the temperature of 
 the bath. The top of the stove itself being directly over the 
 fire, makes an excellent bath for those operations requiring a 
 higher temperature. 
 
 This arrangement, or the still more economical gas bath 
 (Fig. 27) described at p. 48, renders necessary the use of 
 Luhme's or Kent's portable furnace for fusions, crucible or 
 other operations requiring a very high heat, but this involves 
 no additional expense, for such an implement is indispensable 
 for other laboratory purposes. 
 
 The steam generator (Fig. 10) when used as a stove for 
 heating the apartment, answers equally well to heat the bath, 
 it being only necessary to conduct its smoke-pipe into the 
 iron box instead of leading it directly into the chimney. 
 
 To prevent contamination of the atmosphere of the apart- 
 ment, by admixture with the deleterious fumes evolved dur- 
 ing the various operations of digestion, fusing, melting, heat- 
 ing, and evaporating in progress upon the sand-bath and in 
 the furnaces, there should be firmly fastened to the ceiling 
 and immediately over its surface, extending beyond its 
 superficies some four inches all around, a sheet-iron hood, of 
 form at the base corresponding with that of the top of the 
 furnace. The barrel of this hood may pass either directly 
 through the ceiling and roof into the atmosphere,* or else be 
 
 * When the external atmosphere is colder than that within, an air-vent over- 
 head does not thoroughly relieve the room of its noxious vapors, for the cold air 
 rushing in depresses them, — even within the sphere of respiration, and thus 
 prevents their ascent and consequent escape through the hoods. Dr. Murray's 
 very simple and effectual plan of ventilation, is to conduct a funnel-mouthed 
 pipe through the ceiling into a chimney where a constant fire is maintained. 
 To provide against the entrance of smoke by reason of imperfection of draught, 
 
40 
 
 THE FURNACE — THE HOOD. 
 
 formed into an elbow, leading into the main flue of the chim- 
 ney. In either case the draft must be thorough, so as to afford 
 a free egress of the fumes into the atmosphere without. It 
 
 should also be immovably 
 Fig. 9. fixed by rod iron stretch- 
 
 ers, and well payed over 
 with plumbago paint, which 
 is a resistant of the corro- 
 sive effect of the lalToratory 
 fumes, and thus prevents 
 the destruction of the me- 
 tal. The fixture is repre- 
 sented by Fig. 9. It should 
 descend as near to the sur- 
 face of the bath as conve- 
 nience of manipulation will 
 allow ; and to prevent any 
 accumulation of dirt in the 
 interior, it should be fre- 
 quently brushed out with a 
 soft brush ; and for protection to the vessels on the sand-bath, 
 against falling particles, the top of the furnace should, during 
 the operation, be covered with paper. It is advisable at all 
 times, independently of the foregoing suggestion, to keep each 
 vessel covered with plates or clean white paper, which, while 
 protecting against dirt, offers no impediment to the processes 
 of evaporation, digestion, &c. If the hood, instead of being 
 fixed is counterpoised, so as to admit of ready depression or 
 elevation at will, it is a little more convenient ; but that arrange- 
 ment has the disadvantage of liability to accident, for a care- 
 lessness in fastening the suspension cords may create a very 
 annoying damage. Of course, this mode of hanging the hood 
 can only be adopted where the barrel or pipe is straight, and 
 leads directly through the roof; then to protect the exit hole 
 from the wear and tear consequent upon the abrasion of its cir- 
 cumference, it should be fitted with an earthen ware cylinder'; 
 and furthermore, to prevent the entrance of rain through the 
 
 the pipe should be carried to the top of the chimney. The uniformly high 
 temperature of the chimney keeps the pipe constantly hot, and thus the 
 mephitic vapors within the room will be disengaged. By arranging the barrel 
 of the hood as thus directed, an equally effectual disengagement of vapors may 
 be obtained. 
 
THE LABORATORY — THE STEAM GENERATOR. 
 
 41 
 
 Fig. 10. 
 
 slight openings, there should be a spreading flange around 
 the protruding portions of the barrel of the hood, near the 
 roof. 
 
 The Steam Generator. — To the right of the furnace, at a 
 convenient distance, is the portable steam generator F, with its 
 smoke pipe leading into the circular opening of the lateral 
 flue opposite. This is a patent invention by C. W. Bently, 
 of Baltimore, Md. It has a stove-like form, is compact, re- 
 quires no brick work and but very little fuel, and can be 
 set up and removed at will, when it is desired to occupy 
 the flue with other apparatus. The 
 only fixtures requisite, in addition to 
 the machine, are feed pipes to con- 
 vey the water, and conduits for the 
 passage of the steam. It is a most 
 convenient apparatus for the labora- 
 tory, being alike handy for econo- 
 mically supplying hot water to all 
 parts of the building, and for boiling 
 substances, where the direct admis- 
 sion of steam is preferable ; and 
 also for heating the steam baths in 
 the range a little to its left. This 
 mode of applying heat, having the 
 great advantages of safety, conve- 
 nience and regularity, is absolutely 
 requisite in many cases where the 
 naked fire does not ofi'erthat uniform- 
 ity of temperature necessary to the 
 inalterability of certain substances 
 under process. Fig. 10 represents 
 the apparatus. By means of cou- 
 pling screws and flexible lead pipe, 
 (Tatham's most preferable, being 
 smooth within,) the steam may be 
 carried to any reasonable distance in any direction, thus 
 affording great facility in many operations; as the loss by 
 condensation in thus conveying it is inconsiderable. In very 
 cold apartments, however, when the conduit pipe is of any 
 great length, it may very properly be enveloped with woolen 
 listing or other bad conducting materials. Unless this ma- 
 chine is kept in constant use as a heater for the building and 
 4 
 
42 
 
 THE LABORATORY — THE STEAM-BATHS. 
 
 the sand bath, as suggested at page 31, wood is the more 
 preferable fuel, as it admits of ready ignition, and enables a 
 speedier generation of the steam than could be obtained with 
 coal. The lower cock in the figure connects with the feed 
 pipe. The three smaller cocks above, and placed equi-distant 
 from each other, are try cocks, to ascertain the height of the 
 water, by which its supply must be accordingly regulated. 
 The steam conduits are coupled by a cock fitted to the top 
 of the generator. 
 
 The door in the lower part is for the introduction of fuel 
 into the fire hole. 
 
 Steam-baths. — Immediately to the right of the generator, 
 and affixed against the back wall of the room, as at 1 1, plate 
 2, are the steam-baths, mounted in a wooden frame work (Fig. 
 11). Two or three are as many as necessity calls for in 
 the laboratory. They are of copper, and double bottomed ; 
 the inner jacket of one may be of smooth copper, and the other 
 of tinned copper or sheet lead. The larger of the two may 
 have a diameter of thirteen inches and a depth of twenty 
 inches, the smaller being each way five inches less in size. 
 Fig. 11 represents the apparatus. There can be a third, 
 
 Fig. 11. 
 
 with very little additional expense of money or room, and this 
 should have its inner jacket of thin cast iron with porcelain 
 lining, as being more suitable for those operations which are 
 corrosive of metallic vessels. These latter are made to order 
 
THE LABORATORY — THE STILL. 43 
 
 by Savery, the former by Hammet and Hiles, of Philadelphia. 
 The outer jackets h h h are invariably of copper. 
 
 Immediately over the frame work, which is stationary, 
 resting and fastened against the back wall, is a welded wrought 
 iron steam conduit B^ forming the main feeder for the baths 
 a a a. The supply of steam, which is conveyed to each through 
 a pipe c?, connected with the main feeder and fastened to the 
 back of the outer jacket 5, is regulated by the cocks/ and c. 
 The safety valves are supported by uprights e e e^ firmly fixed 
 to the floor beneath. The stop cocks ccc render each kettle 
 independent of the others, so that the use of one does not ne- 
 cessarily compel all to be in operation. 
 
 This apparatus is very convenient for exhausting vegetable 
 matters, such as dye woods, plants, &c., of their matter solu- 
 ble in water, and whose active principles are liable to be 
 damaged by fire. The saving in fuel and time, the perfect 
 freedom from waste steam, the power of regulating the heat, 
 are only a few of the advantages of this mode of boiling over 
 the old plan of heating in open kettles over the naked fire. 
 
 Moreover, when the exhaustion is complete, the heat may 
 be discontinued by merely stopping off the steam with the 
 cock c. By another connection with the hydrant, enabling a 
 current of fresh water as soon as the steam is turned off, the 
 apparatus is converted into a refrigerant, and its contents may 
 be cooled as suddenly as desired. 
 
 Near to the steam series, are two steaming cisterns of 
 an half-barrel capacity each. One may be of deal or oak 
 wood and iron bound, the other of blue stone-ware, from the 
 Baltimore pottery. These tanks are mounted upon pedes- 
 tals, and being readily handled for filling, emptying, and 
 cleansing, are very convenient for those operations where the 
 direct application of steam is necessary. A flexible leaden 
 pipe from the main conduit, leads the steam directly into the 
 vessels, and produces a uniform ebullition. The form of these 
 tanks is similar to that of butter or meat tubs. To prevent 
 the diffusion of the steam through the apartment, the vessels 
 must be kept covered during the operations of boiling. 
 
 The Still. — On the left of the furnace, as at E H, PI. 2, and 
 occupying the same relative position there as the generator on 
 its right, are the still and refrigerant, which are indispensable 
 utensils, both for a supply of pure water for analyses, &c., and 
 for the many distillatory operations connected with chemical 
 
44 
 
 THE LABORATORY — THE STILL. 
 
 research. In its construction there should be particular regard 
 to compactness, so that the implement may combine the double 
 advantage of a naked and water bath still. For convenience 
 and economy of room, we prefer that this apparatus be mova- 
 ble, and therefore recommend, as a substitute for a brick wall 
 bed or setting, a portable stove-like cylinder of thick sheet 
 iron. The fire door is as shown in the figures below, and in 
 order to prevent the overheating of the iron cylinder, the part 
 which contains the fire should be lined with a refractory earthen 
 cylinder, of about two inches thickness, as at h and c, in Fig. 
 12. The smoke pipe leads into the circular opening of the op- 
 posite flue. The body of 
 Fig. 12. the still rests upon the rim 
 
 of this furnace at a, by its 
 flange, which surrounds it 
 immediately below its han- 
 dles. It is shown by (7, 
 Fig. 13. Its dimensions 
 should be so much less than 
 those of the furnace, as 
 to leave sufficient heating 
 space around its sides and 
 bottom. The material of 
 the still is copper, and the 
 joints are rounded so as to give every facility in cleansing. 
 Moreover, round edges are less liable to become bruised than 
 
 NAAAAMAl 
 
 ^ 
 
 iz> 
 
 ^ 
 
 Fig. 13. 
 
 Fig. 14. 
 
 
 ~^ 
 
 t B 
 
 1 
 1 
 
 1 
 
 I'S- 
 
 J 
 
THE LABORATORY — THE STILL. 45 
 
 the angular. For the distillation of substances indestructible 
 at high temperatures, this still is applicable over the naked 
 fire, but for more alterable bodies, the intervention of water is 
 necessary, and so, accordingly, an inner. tinned copper or ena- 
 meled iron jacket is provided. The form and position of this 
 jacket are shown at B^ by the dotted lines in Fig. 13. It is a 
 straight cylinder with convex bottom, and a broad rim, serving 
 also as a flange or rim for its support in the still. Its dimen- 
 sions are four inches in diameter and eight inches in depth less 
 than those of the still. The head or capital, which should be of 
 tinned copper, or, preferably, of pewter, is shown at A, The 
 rim is made to fit the mouth of either the still or water bath, 
 and hence the same head answers in both naked and bath dis- 
 tillations. The beak conveys the vapors accumulating in the 
 capital, into the refrigerant or condenser, which consists of a 
 pewter worm Fig. 14, encased in a wooden tub kept con- 
 stantly supplied with cool water through the pipe e. The 
 water pipe which carries off the heated water displaced by the 
 cold water, runs from the top of the tub, and has its exit 
 into the sink, or through the wall, into the gutter. These 
 two pipes are better of lead. The vapors in passing through 
 the worm are condensed and drop as a liquid into a receiver, 
 which is placed beneath the outlet pipe near the bottom of the 
 tub. 
 
 To convert the apparatus into a water bath, (for in many 
 distillations the temperature must not exceed the foiling point 
 of water or a saline solution,) it is only necessary to charge 
 the outer jacket, or still, with the proper quantity of liquid, 
 and then to insert the inner casing jB, which slides into the 
 mouth and fits tightly. 
 
 In the distillation of flowers, roots, and other substances, 
 in the naked still, a too close contact with its heated sides 
 and bottom renders them liable to injury by scorching, and 
 therefore it is necessary to have a strong wire 
 stand with one or two cullendered shelves upon ^^^- ^^^ 
 
 which to place the material. The lower shelf 
 h being an inch or two from the bottom of 
 still, prevents all liability of contact between 
 it and the material. This apparatus is shown 
 by Fig. 15. When the still is not in use for 
 its legitimate purpose, by removal of the wire 
 
46 
 
 THE LABORATOEY — THE STILL. 
 
 shelving, it becomes an excellent kettle for any of the ordinary 
 boiling operations. 
 
 In the blank space of the wall to the left of the front 
 entrance, stands a deal wood cask, with wooden spigot, 
 mounted upon a stand of convenient height. This serves 
 as a reservoir for distilled water, and the opening for pour- 
 ing in the water must be kept tightly closed to prevent the 
 admission of dust or absorption of gases. 
 
 The Sink. — In the corner of the room to the right of the 
 refrigerant, is the sink. Its position will be better understood 
 by reference to I, PI. 2. As it is necessary that the labora- 
 tory should be abundantly and constantly supplied with water 
 for cleansing, distilling, -and many other operations, it is 
 better in those cities where the water is supplied by public 
 water-works, to make an attachment to the main conduit, and 
 lead the water through a lead pipe directly into the laboratory, 
 and immediately over the sink. The only arrangement ne- 
 cessary is a stop-cock at the termination of the pipe, to regu- 
 late the flow of water. Fig. 16 represents a sink thus 
 arranged. The trough should be of wood and lined with 
 sheet lead, which metal is preferable 
 to zinc ; because less liable to corrosion 
 by acids, for the formation of holes, 
 by amalgamation with mercury, can 
 be avoided with a little care in washing 
 vessels containing residua of it, or the 
 solutions of its salts. The floor be- 
 neath, to a certain extent around the 
 sink, should also be covered with sheet 
 lead, otherwise its continual dampness 
 from the splashing water would endan- 
 ger the health of the operator. When 
 the introduction of water by conduit 
 is impossible, it is necessary to erect 
 immediately over the sink a strong 
 iron-bound oaken reservoir with cover, 
 which must be daily filled with buckets 
 from the neighboring pump. In either 
 case, the exit-cock should be fitted with one of Jennison's 
 filters, a small metallic casing, Fig. 17, containing a stratum of 
 crushed quartz, which arrests the suspended impurities of the 
 water during its percolation through. If it is not convenient 
 
 Fig. 16. 
 
THE LABORATORY — THE STILL. 
 
 47 
 
 to provide one of the above filters, an economi- Fig. 17. 
 
 cal, but slower and less convenient one can 
 be made of a common red earthenware flower- 
 pot by covering its bottom interiorly with a 
 linen cloth and filling it with coarse white sand. 
 The waste-pipe, which must be constructed so 
 as to admit of the free egress of the waste-water, 
 into a drain which conveys its charge into cess-pools or tanks 
 lined with brick, and sunk into the ground. As the emana- 
 tions of foul air from these pools are noxious, they should be 
 placed some distance from the building, and kept well covered. 
 If the situation be favorable, the drains should empty them- 
 selves into a gutter or some running stream, which, in con- 
 ducting away the foul matter, would relieve the air of the 
 apartments of its noxious effluvia. 
 
 In order to prevent the entrance of any unpleasant 
 smell through the apertures by which the water goes down, 
 there should be a hell stench-trap at the commencement 
 of the drain. This addition, which will be furnished to 
 order by the plumber who constructs the sink, has the ad- 
 ditional advantage of retaining particles 
 of solid matters that may fall down. It 
 is shown by figures 18, 19, for which we 
 are indebted to Webster s Eneyelopcedia. 
 "Fig. 18, a h c represents the section 
 of a portion of a hollow cone of metal, 
 having a short pipe in the middle, h d; 
 and water is put into this cone up to the 
 level a e. A loose perforated cover e is 
 made to rest on a shoulder on the top of the 
 cone, and this cover is perforated with two 
 circles of holes; on the lower side of this 
 cover a hemispherical cup is fixed, the edges 
 of which dip under the surface of the water. 
 When water of any kind is thrown on the 
 down through the holes, and finds its way 
 under the edges of the inverted cup, down 
 through the tube d, and so into the drain ; 
 but if any foul air should come back the 
 same way, before it gets out it would have 
 to pass through the water; but from its 
 levity it lodges in the top of the hemi- 
 
 Fig. 18. 
 
 cover, it passes 
 
 Fig. 19. 
 
48 
 
 THE LABORATORY — DRAINING RACKS. 
 
 spherical cup, and cannot descend through the water, unless 
 more pressure is exerted than is usually the case; hence the 
 cup dipping into the water is a complete trap or stop for 
 the air, and effectually hinders any bad smell or noxious 
 effluvia from coming up from drains, which, indeed, should 
 never be without this simple but useful contrivance. These 
 traps likewise prevent the intrusion of rats, &c. This appa- 
 ratus, however, is sometimes liable to be deranged by neglect 
 or bad usage ; and it is proper to construct another kind, of 
 brickwork. Somewhere in the course of the drain let there 
 be sunk a small square well, Fig. 19, g g, built round with 
 bricks laid in cement, and plastered on the inside with the 
 same, so as to be completely water-tight and to remain always 
 filled with water. Across this well let there be a piece of 
 paving stone so fixed that its top may touch the cover of the 
 drain, and its lower edge dip below the surface of the water 
 in this trap or well. On the same principle as the bell trap, 
 no air can pass along the drain, it being stopped by the water 
 below the stone." 
 
 As all the cleansing operations are performed at the sink, 
 it is necessary that it should be fitted with several shelves, in 
 addition to those which may be arranged by its sides. To 
 afford free egress to the draining water, those which are to 
 hold the glass-ware had better be cullendered, and upon one, for 
 the safety of the test tubes and other hollow apparatus of too 
 
 Fig. 20. 
 
 Fig. 21. 
 
 small circumference to stand upright alone, 
 there should be a series of draining-pins as 
 shown by Fig. 20. A rack of horizontal pegs, 
 for draining retorts and other irregular-shaped 
 apparatus, might also be conveniently arranged 
 upon a part of the space. For draining vials 
 and small flasks, an upright stand fitted with 
 pegs, as shown by Fig. 21, is perhaps prefer- 
 able to the horizontal rack. 
 
THE LABORATORY — CLEANSING APPARATUS. 49 
 
 A jar of soft and a piece of castile soap should have 
 appropriate positions in the vicinity of the sink ; and near by 
 also, say on the back of the door, for the sake of economizing 
 room, there must be two long towels hung on rollers as at 
 Fig. 22. One of these towels is exclu- 
 sively for the hands, the other for drying Fig. 22. 
 the cleansed glass-ware, &c. The other 
 accompaniments to the sink are a coarse 
 towel, a small paint-brush, a bottle of 
 shot, a series of wires, some tow and 
 raw cotton, and a wire instrument for 
 the removal of corks from the interior 
 of bottles. This latter is nothing more 
 than three plies of stiff wire united together at their upper 
 ends, and bent in angular forms at their lower ends. The 
 paint-brush is for washing out wide-mouthed apparatus, and 
 can be well substituted by a twine-brush of similar shape, and 
 much used in housewifery for washing tea-china. These and 
 the cork wires are to be had at any house-furnishing esta- 
 blishment. 
 
 Of the series of wires, one should be stiff and skewer-like, 
 with pointed end, to remove those particles of dirt, tena- 
 ciously adhering to bottles, which have resisted the cleansing 
 action of agitation with shot. The remaining wires may be 
 of stiff iron and roughened, or jagged at the ends, in order 
 the more securely to prevent the slipping of the tow or cotton, 
 which is wrapped and tied thereon to facilitate the cleansing 
 of the glasses. The tow or cotton is to be renewed as fre- 
 quently as is necessary to cleanliness. A portion of the wires 
 may be from J to J of an inch thick, and 16 to 18 inches 
 long. The rest for smaller apparatus may be of proportion- 
 ally less dimensions. Several long wedge-shaped oaken sticks 
 are also convenient for more effectually applying the cloth or 
 towel, with which they are temporarily wrapped, to the angular 
 spaces at the bottom of the glasses. All of these pieces of 
 apparatus should have appropriate places near to the sink. A 
 series of pegs or nails are very convenient hangers, and 
 two or four cuddies make serviceable receptacles for the tow, 
 cotton, and rags. 
 
 In those situations where it is not convenient to introduce 
 the water through a pipe, there must be erected immediately 
 over the sink a strongly braced shelf, as a support to a closely 
 
50 
 
 THE LABORATORY — THE TOOL-CHEST. 
 
 covered deal wood cistern for the reception of water. The 
 water is supplied either by buckets full from a neighboring 
 pump or else is pumped in. In the former case, the position 
 of the sink in the corner, and near to the door, allows great 
 facility in filling it. 
 
 Next to the sink, occupying the inner wall spaces on either 
 side of the door, as at m m, PI. 2, are strong shelving cuddies, 
 racks, and pegs, as receptacles for crucibles, furnaces, iron 
 pots, pans, lead coils, and other apparatus needful in the 
 processes and operations performed in the room. 
 
 The corner shelves K, PI. 2, strongly built, are for the re- 
 ception of the larger pieces of apparatus. There should also 
 be reserved a wall space for the still, generator, &c., when out 
 of use. 
 
 The anvil occupying the position L, plate 2, and resting 
 upon a foot-block, is a most useful implement, and a necessary 
 accompaniment to the tool-chest, upon the opposite side of the 
 room, at n, PI. 2. This tool-chest, which is shown by Fig. 
 23, combines in its construction the conveniences of a work- 
 bench. The vice is afiixed 
 Fig- 23. towards the end, so as to 
 
 give full working room. The 
 drawers are receptacles for 
 the requisite tools, among 
 which should be a hammer, 
 hatchet, saw, a chisel of 
 each kind, gimblets, awls, 
 files of the various shapes, 
 pincers, a soldering iron, a screw-driver, with an assortment 
 of screws, nails, &c. A glue-pot will also be found a necessary 
 addendum. The bench should be about four feet in length, 
 and of height suitable to the comfort and convenience of the 
 operator. 
 
 The pedestal o, PI. 2, occupying the space between the 
 door and left front window, supports a barrel-shaped reservoir 
 of deal wood, or preferably of blue stone, (which can now be 
 had at Maulden Perine's pottery, Baltimore,) for the reception 
 of distilled water, a supply of which should be constantly kept 
 on hand. 
 
 A tin match-box, an essential requisite of the furnace room, 
 should have a dry position in some convenient place upon the 
 wall. 
 
THE LABORATORY — THE OPERATING ROOM. 
 
 51 
 
 The charcoal, coke, and sand can either be kept in the cel- 
 lar, or else in bins occupying the base of the shelving, and 
 resting immediately upon the floor. 
 
 A solid oaken pedestal for the iron mortar, and several 
 wooden buckets for general convenience, are also necessary 
 pieces of furniture. 
 
 All operations emitting corrosive or disagreeable vapors 
 should be confined, as far as possible, to this room. In passing 
 sulphuretted hydrogen, chlorine, or sulphurous acid through 
 liquids, the vessels should rest either upon a shelf projecting 
 out of the window, or else under a hood which can carry the 
 emanations into the flues, and thus prevent much corrosion 
 of apparatus and discomfort to the operator. 
 
 CHAPTER IV. 
 
 THE OPERATING ROOM. 
 
 Fig. 24. 
 
 Between the office and the furnace room, and occupying the 
 whole residual floor space C, PL 2, of the apartment, is the main 
 operating room (PI. 1 ), of dimensions on the plan, 24 by 18.6 feet. 
 In this room are performed all the more delicate manipulations 
 of analysis and experimental research, and hence the necessity 
 of great cleanliness. The arrangement prescribed frees it 
 entirely from the dust of the 
 coarser operations of the fur- 
 nace-room, (the door of which 
 should be kept constantly 
 closed,) while the counter- 
 poised windows, of adequate 
 dimensions to afford abundant 
 light, are also capable of main- 
 taining thorough ventilation. 
 In this room are stored nearly 
 all the finer apparatus and 
 materials. The main feature 
 of the apartment is the ope- 
 rating table, which is shown 
 by Fig. 24. Its position (M, 
 
 
 ° 
 
 = 
 
 o 
 
 'Y^ 
 
 » 
 
 o 
 
 o 
 
 ^ 
 
 
 f 
 
 
 ~\ 
 
 • 
 
 ^i 
 
 . »- 1 
 
 ^ 
 
 
 \ 
 
 o 1 
 
52 THE LABORATORY — THE OPERATING TABLE. 
 
 PI. 2) is against the front wall space between the middle 
 and left window. It may be constructed of pine wood, though 
 cherry or walnut is preferable. At all events, the top, which 
 must project over all around 2 inches, should be either of 
 these woods or ash, and at least of an inch thickness; glued at 
 the grooves, and grooved and clamped at the cross-grained end, 
 so as to prevent warping or shrinking, either of which creates 
 a great inconvenience to the operator. It is indispensable that 
 the stuff be well seasoned and joined, because any shrinking 
 will leave loop holes for leakings to penetrate into the drawers 
 beneath, and injure their contents. When the top is made 
 and jointed as thus directed, it obviates the necessity of cover- 
 ing with sheet lead, which, though more durable, endangers 
 the safety of glass and other fragile vessels placed upon it. 
 The height of the table proper is 3 feet. Depth 2 feet 10 
 inches. The length of the top is 4 feet 10 inches. The shelf- 
 stand or test case, which slides in grooves, and is fastened to 
 the top of the table by screws, is 30 inches in length, and 30 
 to 32 in height. The distance between the shelving is unequal, 
 in order to accommodate the different sized bottles. The space 
 between the lower and first shelf may be 10 inches, diminish- 
 ing gradually upward, so that the interstice between the top 
 and topmost shelf shall not be greater than 5 inches. The 
 shelves may be of light stuff, say j inch thickness. The upper 
 drawers should have a depth of 2 J inches ; the lower 3J inches. 
 The closets below should be fitted, the one on the right, with 
 movable shelves, the other on the left with rows of wooden 
 pegs, obliquely hung. 
 
 This table thus constructed is the operating table of the 
 experimenter, and must be furnished with such apparatus and 
 materials as are in constant requisition, and hence the con- 
 venience of the shelving, drawers and pegs, as their recepta- 
 cles. As it is desirable that the table should not be encum- 
 bered with apparatus in unnecessary amount, only those 
 pieces which are of constant use, and required to be at hand, 
 should find an abode within the limits of this table. The 
 general supplies of the laboratory are stored elsewhere, as will 
 be directed hereafter. 
 
 One of the upper drawers should be reserved for filters of 
 the different kinds of paper used for the purpose. These may 
 be purchased, already cut, and of the different sizes, neatly 
 put up in boxes, of Kent of New York. If they are made in 
 
THE LABORATORY — THE OPERATING TABLE. 
 
 53 
 
 the laboratory, it is necessary to have a series of circular tins, 
 corresponding with the size of the funnels most in use, by 
 which to shape them. 
 
 Another drawer may be reserved for small tubes, rods, 
 pipettes, and glass or porcelain connections. Another for 
 platinum crucibles, spatulas and fine metallic vessels. 
 
 The small retorts, bulbs and the like should also have an 
 appropriate drawer. The larger retorts and glass apparatus 
 find appropriate places in the cupboards. 
 
 The top drawer to the extreme right should be fitted up in 
 desk-form, and furnished with pen, ink and paper, for the con- 
 venience of making rough notes during operations, which are 
 afterwards to be neatly transcribed in a note-book, or " Record 
 of Laboratory Operations," kept especially for the purpose in 
 an appropriate place in the office desk. The valuable infor- 
 mation which can in this way be stored up, in a short time 
 amounts to a vast fund, which may, to the great convenience 
 and advantage of the writer, serve as a remembrancer of facts 
 acquired and of errors avoided. A coarse towel should always 
 be an accompaniment to this table, and have a hanging posi- 
 tion at its side. 
 
 The two lower drawers beneath the closets may be reserved 
 for the more weighty implements. 
 
 A leaden funnel, supported by a wooden casing, with its 
 barrel united to a leaden pipe leading through the floor into 
 the street gutter, and placed immediately to the right of the 
 table, would be very convenient for receiving and conveying 
 off the slops from the test tubes. When this arrangement is 
 not practicable, a bucket must be substituted, and emptied 
 daily, for the practice of emptying test tubes upon the floor is 
 
 Fig. 25. 
 
 JJJJJJUUJJJL 
 
 mMmMif 
 
54 
 
 THE LABORATORY — THE SPIRIT LAMP. 
 
 Fig. 26. 
 
 slovenly and reprehensible, and by keeping it constantly damp, 
 the comfort of the operator is greatly impaired. 
 
 A rack with test tubes, Fig. 25, may be considered one of 
 the fixtures of the operating table. 
 
 The spirit lamp which furnishes the heat for table opera- 
 tions, and is shown by Fig. 26, will be spoken of more 
 fully hereafter. When coal gas can 
 be commanded, it is far more con- 
 venient and economical, and by a 
 particular arrangement, may be made 
 to yield heat enough for evaporation 
 and ebullition in capsules, and the 
 different operations of digesting in 
 bell glasses, &c. By the use of a 
 large argand burner fixed over the 
 jet of the table blow-pipe. Fig. 30 
 we can obtain the power of a blast. 
 The admixture of the gas, in this way, 
 with atmospheric air, increases the 
 heat to such an extent as to allow 
 the ignition of precipitates in cruci- 
 bles, and the almost entire dispensa- 
 tion of FURNACE fires in table opera- 
 tions. The arrangement by which 
 these results are accomplished, so as 
 to avoid entirely the deposition of 
 carbon on the bottoms of the vessels, is shown by Fig. 27. B 
 
 is a cylinder of sheet cop- 
 
 Fig. 27. 
 
 lead depending from. 
 
 per, stretched over the top 
 of which, and fastened by 
 an iron hoop, is a fine wire 
 gauze, covered with fine 
 gravel to protect it from 
 wear and tear. In order 
 to promote a more tho- 
 rough admixture of the 
 gas and atmospheric air, 
 (which is effected in the 
 chimney,) there is a coarse 
 wire gauze diaphragm c. 
 The gas pipe of flexible 
 and connected by a gallows screw 
 
THE LABORATORY — THE GAS FURNACE. 55 
 
 A, with the permanent hanger o, terminates in an argand 
 burner d. To prevent a scorching of the table, the burner 
 and cylinder both rest upon a fluted plaster tile. The air 
 enters through the openings in the lower circumference, being 
 drawn up by the upward current of gas, which is let on and 
 regulated by the stop-cock r; and the mixture thus formed 
 passing through the upper fine wire gauze, above which it is 
 ignited, should burn with a bluish flame. 
 
 " Where the quantity of gas is too great for the amount of 
 air admitted, the flame will be white and smoky, but by regu- 
 lating the supply of gas, the due proportion for a blue flame 
 may be easily attained. Now, to obtain a blue flame from a 
 cylinder of large diameter, a considerable quantity of gas will 
 be requisite, and hence an economical advantage is gained by 
 employing cylinders of different diameters. In the same 
 cylinder, also, where different quantities of heat are desired, 
 the lower series of holes may be made large, and a ring of 
 sheet-iron slid over them, by which the quantity of air ad- 
 mitted may be regulated according to the quantity of gas 
 consumed. The cylinders may be 2 J to 5 inches diameter by 
 6 — 8 inches in height ; but by introducing several pieces of 
 coarse gauze, <?, at short distances apart, the height may be 
 diminished. The highest amount of heat produced by this 
 apparatus is a cherry-red by daylight. For burning off" filters 
 in a platinum crucible, a cylinder of 2J inches diameter is 
 amply sufficient ; but for heating larger vessels, such as cap- 
 sules, those of 4 — 5 inches diameter are desirable. This mode 
 of burning the gas presents the advantages of producing any 
 degree of heat as high as a red, of not blackening vessels im- 
 mersed in the flame, and of avoiding, with more certainty, the 
 fracture of porcelain or glass vessels, from the diffusive cha- 
 racter of the flame." 
 
 The ring n, sliding upon the rod of the upright stand A, 
 serves as a support for a retort, capsule or crucible. A second 
 chimney g placed over the crucible creates a uniform and 
 constant draught. 
 
 The whole of this apparatus is movable, and when the space 
 which it occupies upon the table is required for other purposes, 
 it is only necessary to disconnect it from the hanger, and 
 place the whole aside, to be as readily replaced again when 
 wanted. 
 
 The introduction of gas into the room also allows the substi- 
 
56 
 
 TH5 LABORATORY — THE TABLE SAND-BATH. 
 
 tution of an economical table sand-bath (Fig. 28), for the more 
 cumbersome one described at pp. 30, 31. It consists of a copper 
 
 Fig. 28. 
 
 Y 
 
 box B eighteen inches long, twelve inches wide and six inches 
 deep. The top, which is lodged, projects over about an inch 
 and forms the bed for the sand. The door c having a small semi- 
 circular opening at its base, is for the entrance of the gas 
 pipe with an argand burner attached, as well also for the 
 supply of air necessary to sustain combustion. The fire thus 
 applied heats the sand on the top. The heated air has an 
 exit through the circular aperture a, after having traversed 
 the interior, which is divided lengthwise by the partition 
 as represented by the dotted lines. The communication 
 between the apartments is by an opening d in the dia- 
 phragm. In this way we obtain a graduation of the tem- 
 perature of the bath. The Swedish chemists improve upon 
 this construction, by annexing an apartment for drying filters 
 and precipitates as well as for keeping liquids hot while filter- 
 ing. 
 
 These, with the test bottles and contents, complete the para- 
 phernalia of the operating table, and so we proceed to describe 
 the next most important piece of furniture of the room. 
 
 The Centre or G-eneral Table. — This table, (N, PI. 2,) com- 
 pactly fitted to serve the double purpose of an operating table 
 for distillations, and other large general operations of the labo- 
 ratory which would occupy too much room upon the smaller 
 table. Fig. 24, has its top, also of cherry, projecting two 
 inches all around and grooved, glued and tightly jointed, as 
 directed for the preceding table, like which, its lower portions 
 may also be of white pine. Its position is near the centre of 
 
THE LABORATORY — THE CENTRE-TABLE. 57 
 
 the room, so as to afford free access to all its sides. Fig. 29 
 
 Fig. 29. 
 
 ! Hi - !l - li » 1! HI ^ II - 1 
 
 
 1 O O O j o 
 
 i- 
 
 u \ 
 
 Id 
 
 
 i 
 
 gives a view of it. Its dimensions are 2.10 feet height; 
 %,^ feet length; and 3.4 inches breadth. In order to ensure 
 perfect stability, the legs are fitted to a bed which is to be 
 firmly screwed to the floor, so that the table may be stationary 
 and free from oscillatory motion, as any jarring may create 
 serious damage to a delicately arranged apparatus. 
 
 The drawer space should not exceed 15 inches of the whole 
 height of the table. The end drawers are necessarily, from 
 the construction of the table, very short, and may be omitted 
 entirely, though it is better policy to have as many receptacles 
 as possible, for they will all be found useful as well as con- 
 venient. 
 
 Of the front drawers, one should be appropriated exclu- 
 sively to the sheets and other articles of India rubber. Ac- 
 companying these must also be a pair of shears and a ball of 
 very fine linen twine for fashioning and securing joints. 
 Another drawer must be reserved exclusively for the corks of 
 assorted sizes. Two smaller apartments or divisions are also 
 necessary, one for the rat-tail files of different sizes, and the 
 other for the cork borer, of which more will be said hereafter. 
 
 The stock of filtering paper is also kept in another of these 
 drawers; and with it, the circular tins by which it is cut 
 into different sized filters. The shears for cutting the paper 
 should be kept always sharp and clean. Another drawer 
 divided into compartments is required for the reception of tow, 
 5 
 
58 
 
 THE LABORATORY — THE BLOW-PIPE. 
 
 raw-cotton, bladders, string, &c.; and another for the clean 
 dusters and towels of the establishment. 
 
 The filtering cloths and material for that purpose are also 
 kept in a separate drawer. The thermometers and hydro- 
 meters are likewise kept in a distinct drawer. 
 
 There are many other articles which are better preserved 
 in drawers, and hence there is a necessity for the whole num- 
 ber in the table. The short drawers in the end of the table 
 can be reserved for minor matters, such as the scratching- 
 diamond and similar implements. 
 
 The lower bed of the table forms an excellent shelf for the 
 filter stands, retort-holders, clamps, supports, and other wooden 
 apparatus in frequent use upon the operating table. 
 
 All the iron stands and similar apparatus should be painted 
 with black varnish* in order to preserve them from rust. In 
 the selection of iron hollow-ware for purposes of ebullition, 
 or evaporation, choose that which is enameled internally ; — it 
 is more convenient, readily cleansed, and not much more costly 
 than the naked iron ware. 
 
 The mouth blow-pipe table occupying a position against 
 the front wall, and immediately under the right window, as 
 
 Fig. 30. 
 
 * To fused asphaltum, 40 ozs., add a half gallon of boiled linseed oil, 6 ozs. 
 each of red lead and litharge, 4 ozs. dried and powdered white copperas. Boil 
 for two hours, then mix in 8 ozs. of fused dark amber gum, and a pint of hot 
 linseed oil, and boil again for two hours more. When the mass has thickened, 
 withdraw the heat and thin down with a gallon of turpentine. 
 
THE LABORATORY — THE AIR-PUMP. 59 
 
 shown at p PI. 2, is an indispensable piece of apparatus 
 which will be more fully spoken of under blow-pipe operations. 
 
 The blast or pneumatic table (shown in position at q PI. 
 2), which is sometimes also called the table blow-pipe, may be 
 considered as an implement indispensable to the chemist, it 
 being alike useful for bending glass tube, blowing bulbs and 
 other small apparatus, and for rapidly effecting the decompo- 
 sition and ignition of substances, which, for their fusion, would 
 require an ordinary wind furnace. The most convenient form 
 of this apparatus is shown by Fig. 30. The drawing is taken 
 from one, in Professor Booth's laboratory, made by J. Bishop, 
 machinist of this city. It consists of a brass cylinder piston 
 2, worked by a treadle which drives the air into a large tin 
 box enclosed in a frame-work 1 immediately under the top 
 of the table. From the front end of the box a tube rises 
 through the table top, and terminating with its small jet 
 within the interior of an Argand burner, urges the air di- 
 rectly upwards, producing a full flame. The Argand burner 
 may be connected with a lamp or reservoir, containing a solu- 
 tion of oil of turpentine, or alcohol, or with a 
 gas pipe. In the former case, the burner has Fig- 3i. 
 a circular wick with a contrivance for adjust- 
 ing its height. The latter, being neater, and 
 always ready, is almost exclusively used in the 
 laboratory, as giving a powerful flame which may 
 be elevated or depressed at pleasure. With one of 
 the new fashioned Argand gas burners as shown by Fig. 31, 
 this table forms an excellent substitute for ordinary furnace 
 operations. — (Encyelopoedia of Chemistry.) 
 
 Air-Pump, — The small table, at r PI. 2, is used for the 
 air-pump which, when not in use, should be kept in an appro- 
 priate place in one of the cases in the balance room. Being 
 a costly apparatus, it is now almost exclusively replaced 
 by syringes, which are more economical and not much less 
 convenient, as made for the purpose at the present time. 
 For the sake of a convenient uniformity, the attachment 
 screws should have a thread similar to that of the stop- 
 cock, so as to admit of a ready adaptation to each other 
 when an attachment is to be effected. Of the many opera- 
 tions in which the syringe is made to assist, may be men- 
 tioned the displacement of air in retorts, globes, and other 
 vessels, &c., previous to the introduction of gases, and also in 
 
60 
 
 THE LABORATORY — THE AIR-PUMP. 
 
 the exhaustion of receivers for experiments with atmospheres 
 of less than ordinary pressures. 
 
 In order that these machines may work properly, it is ne- 
 cessary that the joints should be tight and free from leakage, 
 and that the pistons be well oiled so as to promote their easy 
 motion. An excellent method of preserving this apparatus 
 in good order, is to work it frequently even when not in use, 
 for by this mode, the elasticity of the pistons and ready play 
 of the cocks may be retained. Fig. 32 represents a horizontal 
 
 «r Fig. 32. 
 
 double cylinder air-pump, invented by A. L. Kennedy, M. D., 
 of this city. The advantages of this apparatus over the old 
 form, are stability and portability, and greater cheapness. 
 Besides, it is more easily and readily worked. Unlike the 
 upright cylinders, this pump is not liable to tilt over whilst 
 being worked, and consequently there is not that instability 
 so annoying when using the barometer gauge. 
 
 "In the figure, L, L represent the barrels, the enlarged ends 
 of which are let into the board and bolted through to insure 
 stability. There is one rack; the two pistons being attached 
 to its extremities. A portion of the rack is exposed at T. 
 The semi pinion w, works in cast straps, or gudgeons, attached 
 to the bottom of the board by screws, which, passing through, 
 terminate in the rack guides, one of which is seen above. 
 The forward gudgeon is so cast as to receive the end of the 
 clamp which secures the pump to the table. The semi-pinion 
 
THE LABORATORY — THE AIR-PUMP. 61 
 
 works upwards through a slot cut in the board, and of course 
 between the rack guides. The upper extremities of the guides 
 are perforated to receive rollers, against which the back of 
 the rack may work when necessary. None have yet been 
 required. To the axis of the semi-pinion the handle is attached 
 in the usual manner. The piston may be either solid or 
 valved, and the cylinders may communicate with the plates 
 R and B, in the way most approved by the maker. In the 
 pump from which the sketch is taken, the pistons are solid. 
 The farther extremities of the cylinders bear female screws, 
 which connect with corresponding male screws on the block. 
 On the posterior portion of each block is cut a female screw; 
 the male of which bears the valve, of course opening inwards, 
 V, V. On those portions of the blocks which project into the 
 board are cut male screws bearing valves opening outwards. 
 Perforated nuts over these secure the blocks to the board, and 
 the valves against injury. At v, v is attached the tube lead- 
 ing from the plates. D is the screw for restoring atmospheric 
 pressure. The general stop-cock s, connects this with the 
 parallel tube which, bearing the gauge cock s', forms at plea- 
 sure a communication between the plates. 
 
 The original of the figure both exhausts and condenses. 
 The remaining letters refer to the parts used in condensing. 
 This is effected by simply connecting, by means of tubes under 
 the board, the valves f', f with a third tube passing upward 
 to the stop-cock K. Then the air drawn in at R, will be con- 
 densed in a receiver screwed on c. Those familiar with 
 Pneumatic chemistry need not be told of the facilities thus 
 afforded for the transfer of gases. The condensing gauge is 
 borne by the screw G. To the practical chemist, it is un- 
 necessary to dilate upon the advantages that result from lower- 
 ing the centre of motion to a level with the points of support, 
 bringing both plates directly under the operator's eye, and 
 presenting, at about the cost of an ordinary exhausting pump, 
 an instrument furnished with all the facilities for exhaustion, 
 transfer and condensation, without any shifting of parts." 
 
 The table s PI. 2, to the right of the air-pump, is a stand 
 for the common scales of the laboratory, which are useful for 
 testing the weights of materials purchased and for weighing 
 coarser articles in large quantities. A cheap platform balance 
 with a movable tin dish answers conveniently for this purpose. 
 The accompanying (Avoirdupois) set of weights should range 
 from \ oz. to 8 lbs. 
 
62 THE LABORATORY — THE CUPBOARDS. 
 
 The next fixtures to be described are the cupboards. Those 
 affixed to the partition of the furnace room as at t and u PI. 
 2 are more properly shelves, with curtains instead of doors to 
 protect their contents from the dust. The set t may be occu- 
 pied with the leaden coils, wooden and coarser apparatus of 
 the apartment. The curtains of common muslin, rendered 
 fire proof by immersion in a solution of borax and sal ammo- 
 niac and drying, are hung by means of small brass rings upon 
 an iron rod running the whole length of the cap of the shelv- 
 ing; and in order to keep them distended, leaden bullets 
 should be sewed at occasional distances upon the lower ends. 
 The shelving u ascends to only half the height of that of t 
 because the upper space is to be reserved for racks and rings. 
 The shelves are intended as receptacles for the porcelain cap- 
 sules, crucibles, &c., the bell, beaker and other similar glass 
 apparatus, always taking care to occupy the lower shelves 
 with the larger and heavier articles. The tube rack is nothing 
 more than a series of pegs, placed closely adjoining in a 
 straight line and inclining upwards so as to prevent the tubes 
 from falling through. This open work presents the whole 
 stock of tubing to view at one glance, and enables a ready 
 selection of any particular piece of rod or tube. The smaller 
 pieces which would be apt to fall through, should be kept in 
 a drawer of the centre table specially appropriated for the 
 purpose. The remaining portion of the upper space must be 
 furnished with a series of various sized spikes to hold retort 
 and flask rings. These rings, readily made of wire, vary in 
 size from a half to two or more inches in diameter, and receiv- 
 ing the necks of retorts and other curved or bent apparatus, 
 retain them in a safe and convenient position. The rings 
 may also occupy any small vacancies upon the walls for the 
 use of such a portion of the apparatus as the cupboard cannot 
 contain. 
 
 The small cupboard {v PI. 2) in the corner opposite, may 
 be used as a sort of general cupboard for very nice little mat- 
 ters, which require great care and cleanliness in their preser- 
 vation. The door consequently should be fitted with a fastening 
 and kept constantly closed when not in use. 
 
 The cupboards w and x erected against the partition 
 opposite, and occupying the spaces on either side of the 
 entrance into the office are, the one x for the stock of drugs 
 and chemicals; the other w for the new empty bottles, to be 
 
THE LABORATORY — THE BOTTLES. 63 
 
 confined to the lower shelves, and for the specimens that may 
 from time to time be accumulated by the labors of the opera- 
 tor. The lower half of the cupboard X should be furnished 
 with small drawers similar to a druggist's case. These are 
 for the dye woods, sulphur, chalk, and other similar coarse 
 articles of stock which are more securely kept in this way than 
 in bundles, which are liable to rupture and damage by rough 
 handling and by retaining moisture. The upper shelv- 
 ing is to be exclusively occupied with the articles in bottles, 
 which are to be arranged in groups, the compounds of each 
 base forming a group. The mineral and vegetable acids and 
 organic compounds, have also each a separate position. The 
 weightier articles as elsewhere directed, should always occupy 
 the lower shelves, both for convenience of handling and on 
 account of their greater stability and power of bearing heavier 
 weights than the upper shelves. 
 
 The black board y PI. 2, is hung sash-like between the up- 
 rights of the cupboard w and x and, being counterbalanced by 
 weights, can be lowered or raised at will, and thus presents 
 no hindrance to egress or ingress from and to the office. For 
 rough calculations and plans, drafts of apparatus, diagrams, 
 &c., the black board is very convenient. When a hand slate 
 is substituted, the pencil should be of talc (French chalk) 
 which makes a more distinct mark than the common slate 
 pencil, and gives more facility in writing. These pencils 
 are now sold in most of the stationery stores. 
 
 Bottles. — Particular regard must be had to the shape 
 and material of bottles for laboratory use. Those intended 
 for holding acids or salt solutions, must be of well annealed 
 glass, which is free from lead and can resist the corrosive 
 action of their contents. Some glasses containing an excess 
 of alkali, gradually lose their brilliancy by absorption of mois- 
 ture from the atmosphere; others again are attacked by acid 
 and alkaline solutions ; and some indeed, even by prolonged 
 contact with boiling water. 
 
 The inalterability of glass by air or chemical agents (hydro- 
 fluoric acid excepted) is proportional to its hardness and infu- 
 sibility. Flint glass is the most brilliant and comparatively 
 fusible, and its consequent pliability renders it available for 
 thermometer and barometer tubes, but as material for chemi- 
 cal vessels it is far inferior to the Bohemian glass (a silicate 
 of potassa and lime with large traces of alumina), which is 
 
64 
 
 THE LABORATORY — THE BOTTLES. 
 
 harder, lighter, and while possessing many better qualities 
 for chemical ware is, when well made, scarcely less remarkable 
 for beauty than crystal lead glass. 
 
 Care must be taken in the selection of glass apparatus, 
 especially those which are to serve as implements for reactions, 
 to choose such as are free as possible from striae, knots, or 
 bubbles, defects owing to the imperfect mixture of the mate- 
 rials of the glass. The more transparent the glass, the more 
 readily can the interior cleanliness of the vessel be ascertained. 
 The common green glass bottle from the factories of New 
 Jersey, in the absence of better, answers every purpose for 
 the common acids, coarser dry substances, and the solutions 
 of such as are soluble; and are, moreover, economical. For 
 the reagents and finer chemicals, there is a cheap white glass, 
 free from lead, manufactured at Storms and Fox's Fac- 
 tory in Kensington, Philadelphia, which is well adapted to 
 the purposes, and replaces sufficiently the elegant, but at 
 the same time much more costly Bohemian glass which is 
 only to be obtained by importation. The laboratory series 
 should vary in size from one ounce to one gallon, ranging as 
 follows, 1, 2, 4, 8, 16, 32, 64, 128 ounces. The most approved 
 shapes are shown by the cuts below. Fig. 33 represents a 
 
 wide mouth bottle for pow- 
 ders and crystals. It is 
 short and wide, with round 
 shoulders to admit of ready 
 emptying and cleansing, 
 and has a strong tall neck 
 for tightly corking. The 
 corks should be perfectly 
 smooth and of the velvet 
 kind. This shape is equal- 
 ly applicable to the bottles 
 of white glass, as is also that 
 of the narrow mouth, glass 
 stoppered, as shown by Fig. 
 35. The narrow necks and their stopples, must be accurately 
 ground so as to insure perfect tightness. As the cost of this 
 white glass above mentioned is so very little greater than the 
 Jersey green, it would probably be more advisable to purchase 
 the whole suite of bottles of such material. The stopples of 
 the narrow-necked bottles are made nearly spherical, but 
 
 
 Fig. 33. 
 
 Fig. 34. 
 
 Fig. 35 
 
 
 
 
 1 
 
 
 1 
 
THE LABORATORY — THE BOTTLES. 65 
 
 somewhat flattened on the top to project over the mouth so as 
 to protect it from dust. The lips are flat and stout for pour- 
 ing readily. The wide mouthed stoppered bottles are, as to 
 body, similar in shape to the above, but their stopple-heads 
 are flattened and cover both the mouth and the rim. The 
 series of all these bottles consists of the sizes above mentioned. 
 For one or two substances both in solid and solution, which 
 are sensitive to the decomposing influence of the light, nitrate 
 of silver and protochloride of mercury for instance, it is ne- 
 cessary that the bottles be either of dark colored glass or else 
 covered exteriorly with tin foil. For hydrofluoric acid a lead bot- 
 tle is necessary, as glass is decomposed by that body. All solu- 
 tions should be kept in ground stoppered bottles, and if economy 
 is indispensable, let the series consist of as many of the green 
 glass bottles as possible, retaining only as many of the white 
 Bohemian glass as are absolutely necessary for the finer re- 
 agents. Corked bottles are inconvenient and liable to leakage, 
 and their use as permanent receptacles of liquid should, if 
 possible, be entirely discarded. We have consequently not 
 given the shape of a narrow-mouthed unstoppered bottle, 
 though if they must be had, the shape of Fig. 34 with the 
 neck narrowed must be the pattern. 
 
 All bottles with contents must be labeled in full and with 
 symbols. This injunction as to labeling applies with equal force 
 to the beaker glass upon the sand-bath and the capsule over the 
 lamp, and to every vessel resting upon the shelves or employed 
 in operations, which contain any substance or solid, whether 
 the material or product of any process. An omission of 
 this precaution frequently leads to much confusion, and 
 occasionally to serious errors. Thin writing paper glazed 
 upon one side wdth a solution of gum tragacanth, and divided 
 into small squares of difi'erent dimensions to suit the several 
 sizes of vessels, answers very well for the purpose of labeling 
 operating vessels. With a pencil, or more properly pen and 
 ink, the designation may be written on the label, and thus 
 completed, is to be pasted on the bottle. For bottles contain- 
 ing the chemicals, materials, &c., these paper squares are 
 equally applicable, but for the test series upon which the labels 
 are to be permanent, it is better that the names be etched 
 upon the glass by the action of fluohydric acid. In England 
 they manufacture a bottle for this purpose, with indelible 
 names in black enamel, upon a white ground. They are, how- 
 
66 
 
 THE LABORATORY — CLEANSING OF GLASSWARE. 
 
 Fig. 36. 
 
 ever, costly. As a substitute for either of the two latter, are 
 printed labels after the patterns of those published by La Rue 
 & Co. (110 Bunhill row, London), which contain the full 
 name of the articles, its symbol, and equivalent. Those bot- 
 tles of the test series, which are to contain the acids or other 
 corrosive liquids, wholly or in part volatile, should be provided 
 with ground glass caps. Fig. 36 represents a bottle of this 
 pattern with the label corroded in by fluohydric acid. 
 The mouths of all the test bottles should flange in order 
 to facilitate pouring. The last drop of liquid gene- 
 rally adhering to the lip can be arrested by touching 
 it with the stopple, which catches and re-conveys it 
 to the bottle when returned to the mouth. Let it 
 therefore be a cardinal rule of the laboratory, that 
 no experiment or operation shall be abandoned even 
 for a moment without having the receptacle labeled. 
 There are other laboratory uses, independent of 
 the aforementioned, to which bottles are applicable. The wide- 
 mouthed when accurately stoppered and rendered air tight 
 in the mouth with a little lard or suet, are excellent substitutes 
 for jars, for the reception and safe keeping of gases which are 
 soluble in water or corrosive of mercury, and consequently 
 cannot be collected over either. 
 
 Cleansing of Gflassware. — When bottles or glassware are 
 greasy, the aid of alkali or ashes is necessary for its removal. 
 In open vessels bran or saw-dust, by their mechanical action, 
 will cleanse the surface of grease. In either case hot water 
 
 is a great assistant. An iron or 
 copper kettle. Fig. 37, fitted to the 
 top of the stove or one of the open- 
 ings in the top of the furnace, is a 
 convenient vessel for furnishing a 
 constant supply. The rinsing after- 
 wards may be with cold water. A 
 short twine brush, similar to that 
 used by housewives for washing 
 tea things, is an excellent assist- 
 ant in cleansing operations, and 
 there should be several of them 
 about the laboratory. For alkali, lime as an example, which 
 coats the sides, a little common muriatic acid is requisite. 
 When the dirty matter is fixed and resists the purifying action 
 
 Fig. 37. 
 
THE LABORATORY — CLEANSING OF GLASSWARE. 67 
 
 of these two agents, and also of hot water, resort must be had 
 to the use of shot, which, when agitated with a little water 
 in the interior of the bottle, gradually removes the adherent 
 dirt, which can then be rinsed out with clean water. Care- 
 lessness in leaving behind one or more shot, which frequently 
 secrete themselves in the crease at the bottom, may result in 
 injury to the next contents of the bottle, if it be solvent of 
 metal. Coarse sand and angular pebbles, which are some- 
 times substituted for shot, are apt to scratch the glass, a dis- 
 advantage which does not apply to small round pebbles. The 
 daily ablution of apparatus had better be performed at the 
 close, and after the labors of the day, so that the advantage 
 of the night may be obtained for draining and drying. Re- 
 torts and beaked vessels should be ranged on shelves with 
 circular holes for the reception of their beaks. In this case as 
 well also in that of open vessels, the mouths should always be 
 placed downwards. When it is necessary to dry the cleansed 
 vessel for immediate use, it may be well wiped with a towel 
 exteriorly and then placed upon a moderately heated sand bath, 
 which will soon expel all internal moisture. Wide mouthed 
 vessels can be dried with a cloth. For cleansing test tubes, a 
 goose-feather or stick with a small sponge fastened to its lower 
 end is very convenient. 
 
 The removal of corks from the interior of bottles is eflPected 
 by an instrument consisting of four strands of iron wire, of 
 about one foot length each, united together at one end, and at 
 the other four extremities bent into an angular shape. Being 
 elastic, there is no impediment to its passage through the mouth 
 of the bottle, in the interior of which it is made, by a dexterous 
 management, to catch and secure the cork, which can then be 
 drawn out with the wire. This simple little instrument is to 
 be purchased at any house-furnishing bazaar. A very con- 
 venient substitute is a doubled string ; the loop thus formed, 
 when introduced into the bottle, secures the cork and allows 
 its easy extraction. 
 
 It not unfrequently happens with ground-stoppered bottles, 
 in cases where certain substances form their contents, that the 
 stopple adheres so firmly as to resist all efforts to remove it 
 with the fingers. It is then necessary to tap it gently and 
 alternately on each side with the handle of a spatula, — the 
 spatula being held by the blade, and the bottle, by the top 
 of its stopple — the body resting on the table, in the other 
 
68 THE LABORATORY — THE TEST-CASE. 
 
 hand. In ordinary cases this process loosens the stopper, hut 
 if it fails, it then becomes necessary to carefully expand the 
 neck over the flame of the small spirit lamp, and in order that 
 it may be uniform, the bottle must be kept constantly revolv- 
 ing in a horizontal position. When sufficient warmth has 
 been applied, a gentle tapping of the stopple, as above directed, 
 effects its removal. After the neck of the bottle has cooled, 
 it and the stopper must be washed and dried before the latter 
 is returned to its place, otherwise it will soon become tightened 
 again. The plan sometimes adapted of inserting the head of 
 the stopper in a chink and then wrenching it out as it were 
 by turning the bottle with the hand, is not ad\dsable, as it 
 endangers the safety of both the vessel and hand. 
 
 When the lamp is used, the motions must be dexterous and 
 careful, so as to confine the heat to the neck of the bottle, for 
 if it is allowed to reach the stopper also, the expansion of both 
 being then equal, the removal of the former cannot be effected. 
 The success of the effort depends upon a difference of tempe- 
 rature between the stopple and the neck which encloses it. 
 Friction, induced by drawing a string constantly, and for a 
 length of time, to and fro around the neck of the bottle, is 
 sometimes substituted for the heat of a lamp. 
 
 When the cementing matter is a crystallized salt, hot water 
 placed around the edges will loosen the stopper by dissolving 
 the salt; — when it is metallic matter, hydrochloric acid is 
 necessary, care being requisite that it does not injure the con- 
 tents of the bottle. In some cases olive oil, similarly applied, 
 is more effectual than either hot water or acid. 
 
 These remarks are equally applicable to nearly all kinds of 
 closed glass vessels. Broken glass and odd stoppers being 
 often needed for various uses, should be preserved in a box 
 for the purpose. 
 
 The Test-case. — The bottles of the test-case should be of 
 white glass, entirely free from lead, and nicely fitted with ground 
 stoppers. As they are constantly in use, it is preferable to etch 
 their labels upon the glass. This is readily done by the ope- 
 rator himself, who has only to coat a limited space of the 
 bottle (see Fig. 36) with melted wax, and after tracing thereon, 
 with an iron style, the name and symbol of the reagents to be 
 contained therein, to wet the marks with sulphuric acid, and 
 then sprinkle on some finely powdered fluoride of calcium 
 (fluor spar). The fluohydric acid thus set free attacks the glass, 
 
THE LABORATORY — THE TEST SERIES. 69 
 
 and renders the latter opaque and distinct, whilst the wax 
 protects the other portion from its action, and when removed, 
 presents the smooth surface of the glass. Care should be taken 
 to avoid contact with any of the escaping vapor, as it is dele- 
 terious. 
 
 When paper labels are used they must be payed over wdth 
 a thick coating of insoluble varnish, and written upon with 
 incorrodible ink. The former consists of white of egg (strain- 
 ed), which is to be applied with a camel's hair pencil, and 
 immediately coagulated by steam heat and then dried in an 
 oven at about 212° F. The ink is made by dissolving one 
 part of genuine asphaltum in four parts of oil of turpentine, 
 and adding lamp black to render it properly consistent. The 
 neatest method of marking the labels with the ink is by means 
 of a small stamp and types. When the ink has dried, the var- 
 nish is to be applied as above, but preferably after the label 
 has been pasted (with gum tragacanth) upon the bottle. The 
 transparent film hardened, and rendered insoluble by heat, 
 presents a firm resistance to strong acids, alkaline solutions 
 and other reagents, and, moreover, this kind of label is eco- 
 nomical. 
 
 The test series consists of eighty-two bottles, which have their 
 position in the case over the operating table. Fig. 24. Of this 
 series, there are eighteen narrow-mouthed pints with contents 
 as follows: 
 
 1 Sulphurous acid (in solution) 
 
 SO, 
 
 2 Hydrochloric acid (common) 
 
 HCl 
 
 3 " « (pure) 
 
 HCl 
 
 4 Chlorine water (in solution) 
 
 Cl-fH 
 
 5 Nitric acid (common) 
 
 NO- 
 
 6 " " (pure) 
 
 NO, 
 
 7 Sulphuric acid (common) 
 
 SO, 
 
 8 « « (pure) 
 
 SO3 
 
 9 Nitromuriatic acid (aqua regia) 
 
 NO.-fCl,HO 
 KO4-HO 
 
 10 Hydrate of potassa (in solution) 
 
 1 1 Aqua ammonia 
 
 NH.O 
 
 12 Carbonate potassa (in solution) 
 
 KO.CO. 
 
 13 " soda 
 
 NO.CO. 
 NH^O.CO 
 
 14 " ammoniae " 
 
 1 5 Acetate of lead « « 
 
 PbO,A 
 
 16 Sulphate of lime " " 
 
 CaO,S03 
 
 17 Lime water 
 
 CaO-f-HO 
 
 18 Sulphuretted hydrogen " 
 
 HS 
 
 The next size (narrow-mouthed) is eight ounces, and of 
 these there are nineteen with liquid contents, as follows: 
 
70 
 
 THE LABORATORY. 
 
 19 Acetic acid 
 
 20 Oxalic " 
 
 21 Tartaric" 
 
 22 Phosphorous acid 
 
 23 Ether 
 
 24 Chloride of ammonium 
 
 25 Hydrosulphuret of ammonia 
 
 26 Oxalate of ammonia 
 
 27 Chloride barium 
 
 28 Chloride calcium 
 
 29 Phosphate soda 
 
 30 Sulphate copper 
 
 3 1 Basic acetate of lead 
 
 32 Proto-sulphate of iron 
 
 33 Sesqui-chloride of iron 
 
 34 Sulphate of magnesia 
 
 35 Sulphuret of Potassium 
 
 36 Sulphate of alumina 
 
 37 Infusion of galls 
 
 C4H3O3 or A 
 C2O4, H_ 
 
 C8H,0,o=T 
 
 PO^ 
 
 C,H,0 
 
 NH.Cl 
 
 NH^S+HS 
 
 NH^O,©" 
 
 BaCl 
 
 CaCl 
 
 HO,2NaO,P05 
 
 CuOjSOg 
 
 3PbO;A 
 
 FeO,S03 
 
 Fej.CL 
 
 MgO,!S034-HO 
 
 KS, 
 
 The four ounces number ten, of which the liquid contents 
 are as follows: 
 
 38 Bitartrate of potassa 
 
 39 Acetate " " 
 
 40 Basic silicate " 
 
 4 1 Chloride of mercury 
 
 42 Protochloride of tin 
 
 43 Proto-nitrate of mercury 
 
 44 Chromate of potassa 
 
 45 Sulphate of potassa 
 
 46 Succinate of ammonia 
 
 47 Borate of soda 
 
 K0,H0,T 
 
 KO,A 
 
 3KO,Si3 
 
 Hg,C]2 
 
 Sn,Cl 
 
 Hg,0,N05 
 
 Ka0,Cr03 
 
 KaO,S03 
 
 NH,0,S=(C,H203) 
 
 NaO/iBOg 
 
 The two ounces, eight in number, contain of liquids as fol- 
 lows: 
 
 48 Bicarbonate potassa K0,2C0g 
 
 49 Acetate of baryta BaO,A 
 
 50 Ferrocyanide of potassium 2KCfy 
 
 51 Ferricyanide of potassium K3,Cfy2 
 
 52 Baryta water BaO-fHO 
 
 53 Nitrate of silver AgO,N05 
 
 54 Iodide of potassium KI 
 
 55 Solution of indigo 
 
 The liquid contents of the one ounce test bottles are, 
 
 56 Carbazotic (nitropicric) acid 
 
 57 Nitrate of nickel 
 
 58 Proto-nitrate of cobalt 
 
 59 Nitrate of potassa 
 
 60 Ammonio-nitrate of silver 
 
 C,2H N^0,3-f Aq 
 
 NiO,N05 
 
 C0,N05 
 
 K0,N05 
 Ag0,N05-f2NH3 
 
THE LABORATORY — THE TEST SERIES. 71 
 
 6 1 Bichloride of platinum Pt^Clg 
 
 62 Chloride of gold Au,Cl 
 
 63 Caustic, soda Na,0 
 
 64 Antimoniate of potassa KOjSbOj 
 
 65 Cyanide of mercury HgjCy, 
 
 In addition to the narrow-mouthed, there are required fifteen 
 wide-mouthed glass stoppered bottles, The contents of these 
 are as follows: 
 
 In the eight ounces 
 
 66 Mixture of carbonates of soda and potassa 
 
 NaO,C02-fKO,CO, 
 
 67 Carbonate of lime 
 
 CaO,CO„ 
 
 68 Sulphuret of iron 
 
 FeS 
 
 69 Dry carbonate of soda 
 
 NaO,CO, (dry) 
 
 70 Carbonate of baryta 
 
 BaO,C02 
 
 7 1 Cyanide of potassium 
 
 KCy 
 
 72 Granulated zinc 
 
 Zn 
 
 73 Per-oxide of mercury 
 
 HgO^ 
 
 n the four ounces ; 
 
 
 74 Hydrated oxide of bismuth 
 
 BiO,+HO 
 
 75 Oxide of lead 
 
 PbO 
 
 76 Blue litmus paper 
 
 
 77 Red " " 
 
 
 78 Turmeric " 
 
 
 79 Georgina « 
 
 
 80 Lead " 
 
 
 81 Starch paste 
 
 
 A leaden bottle of two ounces capacity, for the hydrofluo- 
 silicic acid 3HF,-f-2SiF3 completes the series. 
 
 All these bottles should be made heavy, for if too thin, 
 being so frequently handled, they are liable to be broken. Of 
 the preceding numbers, 1, 2, 3, 4, 5, 6, T, 8, 9, 10, 11, 18, 
 23, 25, should be furnished with ground glass caps as shown 
 by Fig. 36; No. 53 must be of dark glass or else covered 
 exteriorly with tin foil. Nos. 77, 78, 79, 80, 81, should always 
 be accompanied with a pair of pincers with platinum points 
 similar to those used in blowpipe operations, as the test papers 
 should never be handled with the fingers. The bottles for 
 alcohol (C^HgOg), and distilled water (HO) may be of common 
 green glass, narrow-mouthed and quart sized. They are fitted 
 with double tubes so as to insure a gradual egress of the 
 liquid; and are designed as conveniences to the operating 
 table, for supplying small quantities of their contents to test 
 tubes and narrow-mouthed vessels without the aid of a funnel. 
 Fig. 38 shows their form and arrangement. 
 
72 ' THE LABORATORY. 
 
 A piece of bright copper and one also of iron are also fre- 
 
 quently needed as reagents. 
 ^^* ■ All of the forenamed reagents must be chemically 
 
 pure, as also the water used in making solutions of 
 them. The processes by which they are prepared, 
 would not be altogether inappropriate to this work, 
 but more pertinent matter demands our space and 
 so we refer the operator to an excellent treatise upon 
 the subject, by Mr. E. N. Kent, practical chemist 
 of New York, and now in the progress of prepara- 
 tion for the press. 
 Besides these reagents, a small stock of which should 
 always be kept in reserve on the shelves of the cupboard, 
 there is required a general assortment of drugs and chemicals 
 in limited quantity. The coarser and cheaper articles of this 
 stock should preferably be purchased from the dealers, but it 
 is advisable for the operator to prepare the costlier ones for 
 himself, not only on the score of economy, but also because 
 of the practice which he will acquire in the manipulations of 
 various processes. 
 
 There remain but few points to be remarked upon before 
 closing our chapters upon the laboratory. We have already 
 enjoined upon the experimenter, great cleanliness, and we 
 now repeat the injunction. The hands should always be free 
 from dirt, and invariably washed with castile or palm soap 
 before going to meals. This precaution is absolutely neces- 
 sary on account of health, for otherwise, in working with 
 deleterious matters, the little particles which secrete them- 
 selves under and around the finger nails, may be conveyed 
 into the system and thereto work an injury. So also, when 
 engaged at one time upon several operations of a difi'erent 
 nature, it is necessary to rinse the hands in passing from the 
 management of one to that of another of them. For this 
 purpose, the hydrant or reservoir with its adjoining hand- 
 towel, Fig. 22, is very convenient. 
 
 To protect the person from dirt, the operator should pro- 
 vide himself with a suitable costume. A long wrapper of 
 linsey or baize for winter, and of Holland linen for summer, 
 is very suitable. A light cap of some cheap material, is a 
 good shield to the hair against the bad effects of dust and 
 vapor. 
 
 In all investigations, the practice of working upon small 
 
THE LABORATORY — RECORD OF ANALYSES. 73 
 
 quantities, will lead to habits of nice and delicate manipula- 
 tion. Besides, it is easier, less costly and fatiguing to manage 
 a small portion of any substance. Record your processes in 
 the laboratory book, to be kept specially for the purpose; — 
 note in detail the modus operandi pursued, and the results 
 with the day and date, so that you may have every facility of 
 drawing a clear conclusion from the results of your labors. 
 
 There are two other books needed, one is the Record of 
 Analyses, in which are transcribed the analyses of such sub- 
 stances as may undergo examination in the laboratory. Their 
 mode of analysis may also be annexed. This record is very 
 useful for future reference. The other book is an ''Index 
 rerum' after the plan of the Rev. J. Todd, author of the 
 Student's Manual. As it is impossible to retain in the memory 
 all that one reads or sees in the numerous works which come 
 under his eye ; and as we meet with much that is valuable, 
 and really worth preserving, we must resort to some other 
 means more practicable and less laborious than copying out 
 extracts. Mr. Todd recommends the habit of making an 
 index rerum of reading. This book consists of several quires 
 of blank sheets, letter form, and is alphabetically classified, 
 so as to exhibit at a glance, the name of the book and the 
 number of the page treating of the subject, the synopsis of 
 which is recorded under its appropriate letter and heading. 
 There are many facts and opinions met in reading, especially 
 in the journals, which are certain to be wanted some day or 
 other, and by thus gradually storing up you save yourself a deal 
 of trouble for the future when there is need of research upon 
 any subject; and in a few years will have accumulated a mass 
 of information of incalculable value in the practice of your 
 profession. Always, as Mr. Todd directs, have your index 
 at hand when reading book, journal, pamphlet, or newspaper; 
 and "when you meet with anything of interest, note it down, 
 the subject, the book, the volume, and the page; and make 
 your index according to subjects as much as possible, selecting 
 that word for the margin which conveys the best idea of the 
 subject," so that there may be no difficulty in finding the 
 original place when it is necessary to refer to it. For example, 
 in reading the journals for this year, you find several articles 
 which you may wish to refer to again, and so note down their 
 subject matter as follows: 
 
74 
 
 THE LABORATOKY — INDEX RERUM. 
 
 ACIDS FATTY. 
 
 G 
 
 GUN COTTON. 
 
 S 
 SUGAR. 
 
 Their constitution^ new theory of^ hy 
 Jas. C. Booth, Journal of the Franklin 
 Institute for 1848. 
 
 Different views of its composition. 
 Encyclopoedia of Chemistry, p. 488. 
 
 Analyses of hy circular polarized 
 light, Report to Congress hy Professor 
 B, S, M'CulloL 1847. 
 
 There are many other minutiae that might be mentioned, but 
 for want of room for more important matter; they will, how- 
 ever, suggest themselves in the progress of operations. 
 
 Habits of industry, close observation and neatness, are in- 
 dispensable to the acquisition of a proficiency in manipulation, 
 without which it will be difficult to form correct conclusions. 
 
 The laboratory which we have described, is well appointed 
 for every branch of research. Many of the implements enu- 
 merated may be dispensed with for ordinary operations, but 
 they are requisite for a complete arrangement, which, as 
 given in the preceding chapters, is not at all extravagant. 
 Moreover, with a little extra industry, the operator can soon 
 realize the outlay for all conveniences, in the manufacture 
 and sale of such pure chemicals as may be in demand. We 
 have provided him with every appliance for the purpose, so 
 that his self improvement may be attended also with pecuniary 
 profit. 
 
 Where the means are limited, it is better that the purchase 
 of apparatus should be gradual, commencing with those pieces 
 which are of most general use. This course judiciously car- 
 ried out, will in time possess the owner of a well stored labo- 
 ratory. All stock and apparatus can be bought from the 
 manufacturer, or importer, at very little over one-half the 
 dealer's prices, for the same articles. 
 
DIVISION — SLICING — CONTUSION. 
 
 75 
 
 CHAPTER IV 
 
 DIVISION OF SUBSTANCES. 
 
 This operation is a mechanical process, by which the sur- 
 face and points of contact of solid bodies are multiplied; 
 thus diminishing, in a high degree, the opposing force of 
 cohesion ; and, consequently, by promoting greater access to 
 its particles, enabling the more ready and rapid action of re- 
 agents upon solid matter. 
 
 The means by which the division of solid matters is accom- 
 plished are manifold, and vary with the nature of the sub- 
 stance to be reduced ; some bodies being pulverizable by almost 
 any of the processes, while others again require a particular 
 method for their reduction. The different modes of operating 
 may be classified as follows : — 
 
 1st. Slicing. — This process applies to fibrous matters, and 
 is practised with a lever-knife, similar to that used by tobac- 
 conists for cutting tobacco, and shown by Fig. 39. 
 
 Fig. 39. 
 
 Being thus reduced to thin slices, the substance is in better 
 form for maceration, &c. ; and, moreover, admits of readier 
 desiccation, a necessary process when it is required to be further 
 reduced under the pestle, or by being grated on a coarse rasp. 
 
 This mode of pulverization by rasping, though particularly 
 applicable to fibrous substances, such as fresh roots and the 
 like, is sometimes used for metals and hard matters. In the 
 latter case, the files must have finer and sharper teeth, and in 
 both instances be perfectly clean, and free from grease and dust. 
 
 2d. Contusion. — In order to attain a minute division of the 
 denser substances, whose particles are very cohesive, resort 
 must be had to the pestle and mortar. The material of this ap- 
 
 <f 
 
76 DIVISION — MORTARS. t 
 
 paratus varies with the nature of the substance to be powdered. 
 To prevent errors, corrosive or caustic matter should never be 
 pulverized in metallic mortars, else by a solution of a portion, 
 or contamination with abraded particles, unavoidable confusion 
 will ensue. The resistant nature of the material of the mortar 
 must be proportional to the hardness of the body to be ope- 
 rated upon. For the harder insoluble substances, those of 
 iron, brass, or steel are generally used. For the less dense 
 and more pulverizable bodies, especially those which are acid> 
 or corrosive, porcelain, wedge-wood or glass is the proper mate- 
 rial. Marble, being readily attacked by acids, mortars of that 
 material are only used for reducing those inert substances which 
 are readily comminuted merely by trituration, such as chalk, 
 neutral salts, &c. This material, as well as glass, is well 
 replaced by porcelain or wedge-wood, which are stronger, and 
 otherwise much less objectionable. There should be an as- 
 sorted series of mortars for laboratory purposes. 
 
 The large iron mortar has its position in the furnace-room, 
 and is permanently and firmly fitted upon a block, in some 
 convenient place, for general use, in pounding ores, metals, 
 and coarser substances. The pestle of this, as of all other 
 mortars, should invariably be of one piece and of the same 
 material as the mortar; because, when the lower part is fitted 
 to a handle, it is apt to become loosened and drop off particles 
 of the cement with which it is fastened, to the injury of the 
 contents of the mortar. The handle or upper portion must 
 afford convenient space for grasping, and the base or lower 
 portion, roughened on its face by use of sand, should diverge to 
 a diameter of about one-fourth of that of the mouth of the 
 mortar. Fig. 40 exhibits a mortar of proper form and pro- 
 portionate thickness as to its different 
 Fig. 40. parts. Its interior form is nearly that 
 
 of the butt end of an egg, so as to pro- 
 mote a constant contact of the matters 
 being contused with the rotating pestle. 
 To prevent the ejection of particles of 
 matter and the escape of dust, and con- 
 sequent inconvenience to the operator, 
 as the case may be, the mortar should be 
 provided with a sheep skin conical cover- 
 let, with a hole in its centre for the 
 passage of the pestle, which is to be 
 fastened around its rim and over its 
 
DIVISION — MOKTARS. 77 
 
 mouth, with a string. Circular pasteboard and wooden covers, 
 of sizes corresponding with the mortars and with a hole in their 
 centres, are often substituted for the conical coverlet. The 
 operator should always stand with his back to a current of 
 air ; and to further guard against the unpleasant or deleterious 
 effects of the fine dusty particles which may arise from the 
 mortar, he can moisten its contents with a little water, pro- 
 vided that liquid is without action upon the substance. Ex- 
 posure to warmth, for the evaporation of the water, will restore 
 the matter to its original dryness. 
 
 All substances formed of an organic tissue should be pre- 
 viously dried, so as to afford greater facility in their pulveri- 
 zation. A previous reduction of ores, and coarse hard sub- 
 stances into lump, by concussion with a hammer upon an 
 anvil, and of roots and the like into slices or bits with a com- 
 mon knife or lever cutter, (Fig. 39,) are preliminary processes 
 which greatly facilitate their pulverization. The substance 
 to be struck upon the anvil should be previously wrapped in 
 strong brown paper. 
 
 Silicious stones pulverize much more readily after having 
 been heated to redness in a crucible, and in that state pro- 
 jected into cold water. This increased friability is occasioned 
 by the unequal cooling of the mass. 
 
 Metals, alloys and the like, which are difficultly pulveri- 
 zable whilst cold, may also be readily crushed when heated to 
 redness. 
 
 When it is required to reduce the substance into small 
 fragments only, it can be broken down by a succession of 
 blows with the pestle. If the substance is very hard, the force 
 of the arm should be added to the descending weight of the 
 pestle, so as to impart power to the blow. A subsequent 
 circular grinding motion of the pestle, continued for a length 
 of time will further reduce these fragments to fine powder, 
 and consequently this movement must be avoided when only 
 a coarse comminution is desired. The mortar must always 
 rest upon a solid foundation, and during the operation of 
 pounding should be occasionally shaken, in order that the 
 coarser particles which mount to the sides may be forced back 
 to the centre of the mortar ; so as to receive the full effects of 
 the descending pestle, which should never be allowed to strike 
 the sides of the mortar. If the substance is to be reduced to 
 a fine powder, the process is greatly facilitated by operating 
 
78 
 
 DIVISION — MORTARS. 
 
 upon only a small portion at a time, as the pestle is less liable 
 to become clogged. 
 
 In the analysis of rare minerals, especially those which are 
 very hard, the reduction is effected in a small mortar of 
 hardened steel. This apparatus, shown by Fig. 41, consists 
 
 Fig. 41. 
 
 O 
 
 (■■ 
 
 A 
 
 I 
 
 '^ 1 
 
 of three separable pieces, each of which is smoothly turned, so 
 as to present an even surface exteriorly and interiorly. 
 is the base piece into the cavity of w^hich the cylinder B fits 
 somewhat loosely. It is this cylinder which receives the 
 mineral to be reduced. Sliding into it is the exactly fitting 
 pestle A^ which being struck successively with a hammer, 
 crushes the mineral to powder without waste of any of its par- 
 ticles by ejection. 
 
 When the powder thus obtained is not yet sufficiently fine 
 for analysis, it must be transferred to an agate mortar, and 
 rubbed with the pestle until reduced to an impalpable state. 
 The pestle and mortar are of the same material, the hardness 
 and smoothness of which render it particularly applicable for 
 the purpose. The motion of the pestle should always be cir- 
 cular, otherwise a perpendicular blow may endanger the safety 
 of the mortar, especially if it has a fissure, as is often the 
 case, running through it. The given w^eight of the mineral 
 for analysis must always be estimated after pulverization; — 
 never previously, lest a loss by ejection, or adhesion to the 
 mortar, or spatula may lead to inexact results. Fig. 42 ex- 
 
TRITURATION — PORPHYRIZATION. 79 
 
 hibits an agate mortar, which can be purchased 
 
 of sizes varying from 1 to 6 inches in diameter. Fig. 42. 
 
 One of about 3J inches width will be most useful. 
 
 It should be selected as free from indentations, 
 
 fissures or cavities as possible, for these faults not 
 
 only impair the durability of the mortar, but 
 
 render its cleansing very difficult. ' An excellent 
 
 plan of removing tenaceously adhering matter from the sides 
 
 or bottom of a mortar, is to rub them with pumice stone and 
 
 water. 
 
 3d. Trituration. — This mode of manipulating with the pestle 
 is applicable to those substances which are friable, and fall to 
 powder by being merely rubbed up by a circular or grinding 
 motion of the pestle, and which would soften and become ob- 
 stinate by being pounded. Chalk and the like, and most of 
 the salts are in the first category ; — the resins and gum resins 
 in the second. 
 
 Sand is added to facilitate the reduction of resins and 
 similar substances, which cake under the pestle, only when 
 they are intended for maceration or solution. Under other 
 circumstances, the medium would be an adulterant on account 
 of the impossibility of separating it. 
 
 The proper material for a mortar for this purpose is white 
 wedge-wood, of form, as shown by Fig. 43. Berlin porcelain 
 mortars, glazed outside and biscuit internally, with broad but- 
 ted, solid pestles, as shown at Fig. 44, are neat and convenient 
 
 Fig. 43. Fig- 44. 
 
 implements, but less available for general purposes than those 
 of wedge-wood, which are stronger, more durable, and will 
 stand harder blows. These are purchased by the diametral 
 inch, and the most convenient size is 6 to 8 inches width at the 
 mouth. It will be well also to have a smaller one of the same 
 material, say of 2 inches diameter at the top. 
 
 4th. Porphyrization. — This mode of pulverization, only em- 
 ployed when it is desired to give the comminuted substance the 
 
80 , PORPHYRIZATION — SIFTING. 
 
 greatest fineness, takes its name from that of the material of the 
 vessels in which it is practised. A small porphyry mortar, hemi- 
 spherical interiorly, or preferably a slab and muller is the 
 apparatus employed. Flint and even glass, which are equally 
 as hard as porphyry, form an economical substitute for that 
 material. It is highly important that the material of the ap- 
 paratus shall be less easily abraded than the substance being 
 ground; for if too soft, the latter becomes contaminated with 
 the particles which are rubbed off, and, 'hence, in exact investi- 
 gations, inaccuracy is caused. 
 
 Porphyrization is generally effected by rubbing the coarse 
 powder between a flat slab and muller, until reduced to an 
 impalpable state. The circular motion of the muller disperses 
 the powder over the slab, rendering it frequently necessary to 
 collect it together in the centre with a spatula, so as to keep 
 it uniformly under the action of the muller. The spatula may 
 be of horn or steel, but is better when of platinum. Fig. 45 
 exhibits a slab and muller. When the 
 Fig- 45. substance under operation is unalterable 
 
 by water, it may be moistened with that 
 liquid, which, by converting it into a 
 paste, facilitates its reduction and pre- 
 vents any waste by the escape of dusty 
 particles. The powdered paste is easily 
 dried by being dropped in dots upon a porcelain plate and 
 exposed to warmth. Those matters which are soluble in or 
 alterable by water, must be porphyrized in a dry state. 
 
 5th. Sifting. — The impossibility of reducing the whole of a 
 substance at once to a uniform state of fineness by any of 
 the preceding processes, renders necessary an occasional sepa- 
 ration, during the progress of pulverization, of the more com- 
 minuted portions from the grosser particles. This is effected 
 by means of a sieve, of which there should be several in the 
 laboratory. A wooden cylinder of about four inches depth, 
 with an accompanying ring of the same materials, constitutes 
 the frame, over which can be stretched a cloth of any required 
 fineness. For coarser articles, fine brass wire is the best 
 material for the cloth, but when the powder is to be impal- 
 pable, bolting cloth (raw silk), or gauze is requisite. Sieves 
 are also covered with hair-cloth, buckram, book-muslin, and 
 iron wire of different sized meshes, each of which has its ap- 
 propriate application. The metallic sieves should have their 
 
 a 
 
 I HIIIIII'ilIM 
 
SIFTING — SIEVES. 
 
 81 
 
 JWi 
 
 \m\U'. 
 
 Hl^illllMI 
 
 ■ 
 
 Iiliiii ■ ■ 
 
 "iiiiliiliiii 
 
 
 
 il'i" 
 
 'fii'ii 
 
 |i'i!i""'i'!ll 
 
 [jLr- 
 
 :-h 
 
 ,;\!/:l::l 
 
 cloths permanently fitted to them. For all the rest, two 
 frames, as above described, one of much larger dimensions 
 than the other, will serve ; as it is only necessary to remove 
 the ring when it is desired to substitute one kind of covering 
 for another. The sieves of cloth, of graduated fineness, can 
 be kept in some secure place, and withdrawn as wanted, and 
 thus we have the economical means of possessing a full suite 
 of sieves from the metallic wire, through all the grades of 
 fineness up to the closest wrought bolting-cloth. The form 
 of a sieve is shown at A, Fig. 46. After the separation of 
 the finer portions by the sieve, the 
 coarser particles are again subjected Fig- 46. 
 
 to grinding and sieving as often as is 
 necessary to convert the whole into 
 the requisite state of uniform fineness. 
 
 Horn scoops or porcelain spoons or if aiiiiriiriri.^ ^' " ^ ^llllll^illlla l .^ 
 ladles are the proper implements for 
 transferring the contents of the mor- 
 tar to the sieve. In some cases a stifi" 
 pasteboard card, being more pliable, 
 is a convenient substitute. The use 
 of the hand, for this purpose, should always be avoided as a 
 slovenly practice. A platinum, horn or bone, or, less pre- 
 ferably, steel spatula may be used to detach the particles ad- 
 herent to the sides of the mortar. To prevent inconvenience 
 or injury to the operator, (who, both in powdering and sieving, 
 should always stand with his back to a current of air,) from 
 particles of dust or acrid poisonous matter, as well also to 
 avoid waste, the sieve should be fitted with a top and bottom 
 covering, as shown at B and (7, in Fig. 46, the upper of which 
 arrests the escape of the light dust into the air and the lower 
 receives that portion which passes through the cloth. These 
 covers are headed with parchment or calf-skin, and the three 
 divisions, when joined together, form what is called a drum or 
 box sieve. The powder is made to pass through the meshes 
 by gently agitating the sieve between the hands. A rough 
 jarring motion will force through some of the coarser par- 
 ticles, and thus destroy the uniformity of the powder, and 
 hence the common practice of tapping it fi-equently against 
 the side of the mortar should be abandoned, unless the state 
 of fineness is immaterial. Some substances, however, as mag- 
 nesia, &c., which obstruct the pores of the cloth, must be 
 
82 LEVIGATION — ELUTRIATION. 
 
 forced through in this manner, and even, if necessary, by a 
 circular motion of the fingers over the interior surface of the 
 cloth. This manipulation frees the meshes of the cloth from 
 obstructions, but it must be carefully done, otherwise the safety 
 of the cloth will be endangered. A sieve is also useful for the 
 admixture of powders of uniform fineness. 
 
 6th. Levigation — is that mode of mechanical reduction 
 which is practised by first rubbing the substance into a smooth 
 paste, and then separating the finer from the coarser portions, 
 by agitating the bruised matters with water. After a sufii- 
 cient repose, the grosser and heavier portions subside, leaving 
 the lighter particles still suspended in the water. This water, 
 after decantation, gives a second deposit of an increased state 
 of tenuity. The third or fourth decantation yields the pow- 
 der of impalpable fineness. The time of repose between the 
 decantations, unless great impalpability is required, should be 
 limited, and only long enough to allow the deposition of the 
 heavier portions. The coarse precipitates are collected together, 
 second and as many more times as necessary, rubbed up as 
 before, and treated with water, until all the lighter portions 
 have been separated. This process applies only to substances 
 unalterable by water. When uniformity of fineness is not all 
 important, one washing even sufiices, and can be accomplished 
 in the mortar without the use of glasses. Alternate pound- 
 ings and washings will eventually reduce and remove the whole 
 contents of the mortar. In washing over gold and other me- 
 tallic ores, where only the heavier portions are to be reserved, 
 the water may be allowed to flow directly into the mortar, 
 which being held in an inclined position, permits its exit, 
 together with the fine dusty portions which are kept in sus- 
 pension by trituration with the pestle. 
 
 This process of levigation is founded upon the difi'erent 
 specific gravities of the coarse and fine bruised matters, and 
 is, therefore, not only applicable for the separation of the 
 particles of homogeneous matters, but also of equally fine mat- 
 ters of unequal densities. In the latter case it takes the name 
 of elutriation. 
 
 All minerals for analysis, which have to undergo ignition 
 with alkalies, should be previously levigated, in order that 
 decomposition may be complete; for if the powder is not uni- 
 form the larger particles will escape decomposition. 
 
 Pulverization in this manner, by uniformly comminuting 
 
GRANULATION — DIVISION BY INTERMEDIA. 83 
 
 the particles, promotes their equal expansion and the escape 
 of contained moisture, and thus prevents the decrepitation of 
 substances when heated. 
 
 The deposited powder must always be dried, by exposure, 
 previous to subjecting it to any other process. 
 
 7th. Reduction hy G-ranulation. — The reduction of metals 
 to a pulverulent state is effected by fusing them in a crucible, 
 and pouring the melted matter, from an elevation, in a thin 
 stream, very gradually, into a bulk of cold water, which 
 is, during the process, kept in constant agitation with a 
 stirrer. The fineness of the resultant granules is proportional 
 to the slowness with which the fused metal was poured into 
 the water. It is more convenient to transfer the metal from 
 the crucible into a ladle, and project it into the water from 
 that more handy vessel, which enables a frequent change of 
 the position of the descending stream, and thus prevents the 
 formation of clots instead of smaller and more solid granules. 
 The fusion of zinc for granulation must be in a covered cru- 
 cible, otherwise it becomes oxidized whilst hot, and partially 
 sublimes by exposure in an open vessel. Zinc may also be 
 finely divided by being beaten, whilst hot, in a heated mortar. 
 
 The process of fusing metals and then agitating the melted 
 matter in a wooden box until cool, reduces them to a state of 
 minute division, but at the same time promotes their oxidation. 
 For general purposes, however, it is not objectionable, and the 
 particles of charred wood with which it becomes mixed can be 
 separated by elutriation. The sides of the box are generally 
 well chalked, to prevent any adherence of the metal; — this 
 also is separable by elutriation. 
 
 REDUCTION BY CHEMICAL MEANS. 
 
 8th. Division hy Intermedia. — This mode is both mechani- 
 cal and chemical, and applies particularly to the noble metals, 
 in foil, which are difficult of pulverization. Honey, sugar, 
 salts, &c., are the most usual media. By binding the parti- 
 cles together, it assists their minute division, and prevents 
 their escape from the mortar. The addition of boiling water 
 solves out the medium, without action upon the metallic pow- 
 der, which then only requires to be thrown upon a filter and 
 dried. 
 
 Phosphorus may be finely divided by fusing it, with alcohol, 
 
84 REDUCTION BY CHEMICAL MEANS. 
 
 over a water-batli, and shaking the contents of the flask until 
 thoroughly cooled. The phosphorus subsides at the bottom in 
 pulverulent form. Camphor, which is obstinate under the 
 pestle, readily yields to its power when mixed with a few 
 drops of alcohol or ether, to destroy its elasticity. 
 
 Silica may be precipitated from lime glass in a pulverulent 
 form, by the digestion of that compound with hydrochloric 
 acid. Silver is obtained in a powder by the decomposition of 
 its nitric solution with a metallic copper rod ; or of its chloride 
 by metallic zinc. Proto-sulphate of iron throws down gold, in 
 a finely divided state, from the solution of its muriate; and 
 spongy platinum is formed by the dull ignition of the ammo- 
 nia-muriate of that metal. These are instances of chemical 
 division by purely chemical means. The extreme state of 
 division thus obtained by the solution and precipitation of a 
 solid body (and also by fusion, a chemico-mechanical process), 
 cannot be effected by any purely mechanical power. 
 
 The sublimation of sulphur into flowers, as also of calomel 
 into fine powder by means of large airy chambers, are instances 
 of comminution by chemico-mechanical means ; — the vaporized 
 particles being prevented from reunion, at the moment of 
 solidification, by the intervention of the cold air. So, like- 
 wise, in cases of division by hydro-sublimation, the interven- 
 tion of aqueous vapor prevents the conjunction of the vapor- 
 ized molecules. Dr. Joslin {Sillimans Journal^ p. 48, vol. 
 V.) treats of this subject in extenso. 
 
 CHAPTER Y. 
 
 THE BALANCE. 
 
 A BALANCE may be considered the most indispensable im- 
 plement of the laboratory, as affording the only means by 
 which the chemist can accurately estimate the quantitative 
 results of his investigations. The construction of this in- 
 strument for determining the relative weight {the measure 
 of the force hy which any body, or a given portion of it, gra- 
 vitates towards the earth) of substances, is based upon certain 
 
THE BALANCE — ITS REQUISITE CONDITIONS. 85 
 
 mechanical principles, of which we proceed to give a brief 
 explanation. 
 
 A balance consists of an upright shaft, supporting, by its 
 immediate centre, an inflexible lever or beam, with arms of 
 equal length and symmetry, to each of which is suspended a 
 dish for the reception of the weights (the power), and the body 
 to be weighed (the resistance). Of the three axes of the beam, 
 that in the middle is the fulcrum or centre of motion, upon 
 which it turns in a vertical plane. The other two axes are at 
 the extremities of the arms. All three axes should be at right 
 angles to the plane of motion, and parallel to each other. 
 
 The requisite conditions of a good balance. — One of the 
 chief conditions of an accurate balance is a free suspension of 
 the beam, in order that it may vibrate with the least possible 
 friction. The two arms must also be precisely equal, so that 
 when empty, or the weight in each dish is uniform, there will 
 be a perfect equilibrium. The sensibility of a balance is pro- 
 portional to the angle formed by the beam with the horizon, 
 when a slightly greater weight is placed in one dish than in 
 the other. This sensibility depends on the position of the 
 centre of gravity of the beam with reference to the line of 
 suspension; this centre must be below that line, but as near 
 as possible to it, so that the slightest weight will cause the 
 beam to oscillate freely. 
 
 As the inertia and friction are proportional to the weight of 
 the beam, it must be made of material entirely free from im- 
 perfections, and so as to combine strength and inflexibility 
 with lightness. It may be of solid steel, rolled brass, German 
 silver, or of a malleable alloy of copper and tin, but not of cast 
 metal of any kind. The upright support can be of brass, and 
 the dishes and suspension frames of platinum. 
 
 The sensibility of the balance increases with the length of 
 the arms, which should, however, have a certain limit, and be 
 as nearly uniform as possible in every respect. When, through 
 unskillful construction, the length of one arm is slightly 
 greater than that of the other, in order to avoid the error in 
 weighing which this defect would occasion, the body to be 
 weighed is placed in one pan, and counter-balanced by weights 
 in the other. The amount of weight required to restore the 
 equilibrium after the withdrawal of the substance is its cor- 
 rect weight. 
 
 In order to avoid friction, the parts of contact should be 
 
86 THE BALANCE — ITS REQUISITE CONDITIONS. 
 
 as few as possible, and the knife edges must be made of highly 
 polished, hardened steel, and the beds or planes upon which 
 they rest, of agate or flint. The accuracy of the balance will 
 depend greatly upon the skill and precision with which these 
 portions and the beam are elaborated. 
 
 A good balance, with 1 to 2000 grains upon each dish, 
 should be sensitive to the one or two-thousandth of a grain. 
 
 " To obtain the greatest degree of uniform precision, it is 
 requisite that the beam should be lifted from a state of rest, 
 in a perfectly level position, and that the stirrups should be 
 lifted, simultaneously, with their loads, from their rests or 
 supports ; also that the oscillations of the stirrups should be 
 prevented or checked at the earliest moment; and, finally, 
 that the whole system should be left at liberty with delicacy 
 and exactitute, so as to remain in equilibrium, or vibrate as 
 the case may be." 
 
 " To command the above conditions, the beam should be 
 supported upon cones, at each extremity, adjusted level with 
 each other, from which it is lifted, by a plane (and not a por- 
 tion of a hollow cylinder, as is usual) which rises under its 
 centre knife edge, and to which it is returned by its depres- 
 sion, the cones guiding the beam to the same position exactly 
 from which it was elevated. 
 
 " The stirrups, in like manner, should hang upon hollow 
 cones or V's, so as to be taken up from, and returned, inva- 
 riably, to the same position. 
 
 " The beam should rest upon its cones, and the stirrups 
 should be supported by their V's at such heights as to relieve 
 entirely the knife-edges, with a sufficient space between them 
 and their respective planes to permit inspection and wiping, 
 when it may be needed. This construction admits of the 
 placing of the weights, &c., and guards the knife-edges from 
 the consequences of displacement during use. 
 
 " The beam should be raised by the elevation of the centre 
 plane, subsequently lifting with it the stirrups with their 
 weights and load, and all oscillation checked by platforms 
 placed in the table under the centre of the stirrups, which 
 should be made to rise simultaneously, and should be counter- 
 weighed to the requisite delicacy. 
 
 " The descent of these platforms, effected by the pressure 
 of a finger on a lever conveniently placed, will leave the 
 stirrups, &c., at liberty to vibrate, or bring the beam to a 
 
THE MINT BALANCE. 
 
 87 
 
 horizontal position, at the will of the operator; being a con- 
 venient, certain, and rapid method of manipulating, not 
 equaled by any other arrangement, and, in fact, essential to 
 a well-constructed balance." 
 
 These essential qualities of an accurate balance for the 
 more delicate operations of the laboratory are comprised in 
 that form of balance used in the United States Mint, and 
 which " combines all the important advantages heretofore 
 known with such improvements as have been the growth of 
 their own experience." The possession of one of these in- 
 struments does away with the necessity of a separate balance, 
 exclusively, for dry assays. 
 
 Pig. 47 gives a front view of this balance. We take our 
 
 Fig. 47. 
 
 description from the Journal of the Franklin Institute, vol. 
 
 XIV. 
 
 Description. — A table, marked A, is furnished with level- 
 ing screws upon the front and back edge, and at each end, 
 marked h. In Fig. 49, which exhibits different views of all the 
 parts, the leveling screws are marked 5, and their positions in 
 the table (the view of the under side of which is given) are 
 marked c. 
 
 The balance is intended to be placed upon a counter, or any 
 other firm support, and the table leveled by means of the 
 screws last described, its true position being indicated by a 
 plumb-line and weight occupying the rear opening in the 
 
88 
 
 THE MINT BALANCE. 
 
 column (Fig. 49, C) ; the plumb-line and weight being mark- 
 ed d. 
 
 The column, marked C, Figs. 47, 49, contains the lifting 
 apparatus, and supports the cap-plate, marked D. The cap- 
 plate guides the lifting apparatus, and supports the V's, or 
 hollow cones, for the stirrups, and is strengthened and stayed 
 by braces, marked E ; the section of which braces is cruciform, 
 with circular ends, for firm bearing upon the plate and base 
 of the column, to which they are secured by screws. 
 
 Figs. 48, 49, exhibit upper and under views of the table, 
 column, plate, &c., also upper and lower end views of the 
 column, showing the means of its attachment to the table and 
 cap-plate. 
 
 d^\ 
 
 3 
 
 The lifting apparatus consists of a winch-handle, marked 
 /, Fig. 49, fitting upon a round shaft, g, with a feather, so as to 
 admit of its convenient removal ; upon this shaft is fitted a cam, 
 A, also secured by a feather ; the cam is carefully constructed, 
 so as to give equal elevation to equal parts of its revolution ; 
 and upon the cam rests a roller, ^, which turns upon a pin in 
 the frame, /, intended to reduce friction, and give facility in 
 raising the beam with its load. 
 
 The lifting frame, /, is forked cross-wise, so as to straddle 
 the shaft and accommodate the cam and roller, at the same 
 time that it allows the necessary vertical motion, without the 
 possibility of being displaced; all of which is exhibited in the 
 two views of the lifting frame marked y, which is also accom- 
 
THE MINT BALANCE. 89 
 
 panied by sections in proximity to the parts which they are 
 intended to explain. 
 
 The handle is so placed as to be on the left when the beam 
 is down and at rest, and to the right when the beam is raised, 
 in the act of weighing, and makes, together with the cam, 
 more than three-fourths of a revolution, the cam having a very 
 slight depression upon its upper, or highest point, into which 
 the roller falls, maintaining it in its position when the beam 
 is raised. It is then extended beyond the centre of the 
 roller, so as to be stopped at the limit of motion, as exhibited 
 h, Fig. 49. 
 
 Fig. 49. 
 
 The lifting frame is forked at the top for the accommoda- 
 tion of the beam. Upon it rests the plane, the top and side 
 view of which are marked A?, for the support of the centre 
 knife-edge, secured to the frame by screws. In balances of 
 ordinary construction, this plane may be made of hardened 
 cast-steel; in finer instruments, of bronze, or brass, with an 
 inserted block of polished agate, secured by fusible metal, or 
 cement. 
 
 The position of the handle, lifting frame, &c., are exhibited 
 with sufficient clearness in the front view. Fig. 47. 
 
 The cap-plate, views of the upper and under sides of which 
 are given at D, Fig. 48, is constructed with horizontal spaces 
 at the centre and each end. In the middle it is secured to the 
 column by four screws, and to the braces B in the same man- 
 ner, the holes for which are marked in all the views. 
 
 The square opening in the middle serves as a guide and 
 7 
 
90 THE MINT BALANCE. 
 
 support to the lifting frame, which must be accurately fitted, 
 so as to prevent any lateral play. 
 
 The horizontal spaces at the extremity of the cap-plate 
 support short pillars terminated by cones, upon which the 
 beam rests; these pillars are secured to the cap-plate by 
 screws passing through it from the under side, the holes 
 through which they pass being large enough to admit of the 
 adjustment of the beam to its proper place, previous to their 
 being permanently fastened down. 
 
 The details of these pillars are given at Z, Fig. 49, the cones 
 being constructed of cast steel, hardened and polished. 
 
 The same space also supports the V's, or guide supports of 
 the hangers, difiPerent explanatory views of which are given in 
 Fig. 49, the V's being marked w, and the hangers n. All 
 these parts have been devised with reference to the simplest 
 and most economical construction consistent with the requisite 
 accuracy, and for affording the greatest facility in the final 
 adjustment of the balance. 
 
 The most important part of the balance is the beam o ; 
 Fig. 49 exhibits side and top views. The projections marked 
 q, are the supports of the beam when at rest ; the conical 
 cavities, indicated by dotted lines, being made to fit the cones 
 marked I. 
 
 This form of beam affords facility in construction, being 
 composed of straight surfaces, without ribs or curves; is well 
 adapted to maintain its form when loaded; affords the least 
 surface for accumulation of dust, and is readily wiped when it 
 may be necessary. The means of adjustment for the length 
 of arm is exhibited at r. Fig. 49. 
 
 It will be seen, that the needle of the balance, which is the 
 subject of description, is pointed downwards, and there are 
 good reasons for this disposition. In the first place it is 
 directly before the eye of the operator, and, therefore, more 
 convenient in use, than it is, when elevated above ; again it 
 may be made longer than the arms of the beam, and will, 
 consequently, describe a larger arc, and thus give more dis- 
 tinct indications, whilst the whole arrangement need occupy 
 no more space than is requisite for the other parts ; and, 
 finally, the needle is protected from external injury by the 
 lifting-frame and column, in the centre of which it is placed. 
 
 The parts which remain to be described have been usually 
 considered of minor importance, but experience has shown 
 
THE MINT BALANCE. 91 
 
 that this estimate is scarcely a just one, inasmuch as they 
 afford facilities for accuracy and rapidity, that leave no doubt 
 of their value, and place them in a most important position 
 in practice. The parts now alluded to, constitute the system 
 by which the operator is enabled to find the equilibrium of 
 which he is in search. It consists of the pedestals, as they 
 have been termed, marked s, Figs. 47 and 48, and the parts 
 connected with them, marked t, u, v and w, in Fig. 48; a 
 light shaft, made of tubular iron, ^, supported by pivots u^ 
 which pivots are screwed through a piece cast on the under 
 side of the table, marked V ; upon the ends of this shaft there 
 are levers, W, upon the ends of which levers, when in place, 
 the pedestals rest. 
 
 The remaining part of this system is a double armed lever, 
 placed in the middle of the shaft, ^, (represented in the en- 
 graving detached,) and marked x', it is connected by a pin, 
 with the trigger, ^, represented in its place in Fig. 48, with 
 the same letter. Upon the other end of the lever, a:, there is 
 a weight, y, capable of adjustment by a screw upon which it 
 traverses, so that it may be made to approach, or recede from 
 the shaft, t. 
 
 The action of this system is easily understood ; its whole 
 object is to depress the platforms by sufficient force, applied 
 by the finger, to the trigger, the counter weight returning 
 them to their original position, after its removal. 
 
 It will be seen, by reference to Fig. 47, that the under 
 sides of the stirrups have a space, represented by dotted lines, 
 in which the platforms are placed, which allows the stirrups 
 to oscillate within its limits, but beyond which they cannot 
 move. This construction is intended to guard the hangers 
 from displacement, and to prevent injury by too much move- 
 ment of the stirrups, an accident very likely to occur, when 
 the pans or weights are hastily removed, especially in the use 
 of heavy weights or large masses. 
 
 The cavity, whose object was described in the last para- 
 graph, forming the under side of the base of the stirrups, is 
 turned as truly as possible in the form of a portion of a sphere, 
 whose radius is its distance from the bearing of the knife-edge. 
 The platforms are adjusted by means of the counter weight, 
 so as to press lightly up against the stirrups, and to follow 
 them when raised. 
 
 It is found convenient in practice to turn the handle of the 
 
92 THE MINT BALANCE — ITS SUPERIOKITY. 
 
 balance but a small portion of its movement, if the weights 
 are not equal on opposite sides, a circumstance to be expected 
 when searching for a weight. The heavy side will remain 
 down, and the needle will indicate whether addition of weight, 
 or its removal is requisite. These trials are continued until 
 the platforms follow up the whole lift, the needle remaining 
 opposite the middle line of its scale, until the handle is stopped 
 by its limit of motion, where it remains. The finger, then, 
 by pushing down the trigger, will depress the platforms, when 
 smaller weights are employed until the needle indicates equi- 
 librium. 
 
 In this balance there is little or no embarrassment from 
 oscillation, because the stirrups immediately accommodate 
 themselves to the position of the weights, the light pressure 
 permitting them to take any position required by the load ; 
 nevertheless, having sufficient power, from their pressure, to 
 prevent any swinging. If from any cause the stirrups should 
 be in motion, three consecutive depressions of the platforms, 
 will bring them to a state of rest, with absolute certainty, and 
 with a loss of time so short as to be entirely immaterial. 
 
 The stirrups are connected with the hangers, by a rod, 
 which is double-jointed, as near to the hangers as possible, so 
 as to allow perfect freedom of motion ; at the same time, so 
 well fitted as to allow no change of position in the parts. On 
 the lower ends of these rods, there are screws and nuts, to 
 regulate the height of the stirrups, together with a jam nut, 
 to prevent any change after the adjustment has been satis- 
 factorily made. 
 
 The bases of the stirrups are designedly made small, re- 
 quiring the use of a dish on the one side, and a platform for 
 weights on the other. This dish and platform being made of 
 equal weight, renders the use of a counter weight unnecessary, 
 and as the balance cannot be used without both, the liability 
 to mistakes from this cause is entirely avoided. 
 
 Kater's and Robinson's balance, which, though more compli- 
 cated, and less preferable for other reasons to the preceding, 
 is the most popular balance for estimating minute quantities 
 with precision ; and, indeed, for all the weighing operations of 
 delicate research. When carefully preserved, it retains its 
 sensibility for many years. Fig. 50 represents one made by 
 Mr. J. P. Duffey, of Philadelphia, who has acquired great 
 skill and accuracy in the construction of fine balances. An 
 
eater's and ROBINSON'S BALANCE. 
 Fig. 50. 
 
 93 
 
 improvement which he has added to those of recent manufac- 
 ture, is both simple and useful. It consists of an elastic 
 spring, A A, Fig. 51, serv- 
 ing as a support for the 
 dishes when the balance is at 
 rest ; and at the same time 
 so arranged, that by the 
 depression of the thumb 
 lever suitably attached, the 
 dishes are thrown off their 
 supports, and the beam put into action simultaneously. We 
 are indebted for our description to Lardners Elements of 
 Mechanics. 
 
 " The beam of this balance is only ten inches long. It is 
 a frame of bell-metal in the form of a rhombus. The ful- 
 crum is an equilateral triangular prism of steel, one inch in 
 length; but the edge on which the beam vibrates is formed to 
 an angle of 120°, in order to prevent any injury from the 
 weight with which it may be loaded. The chief peculiarity 
 in this balance consists in the knife-edge, which forms the 
 
94 ROBINSON'S BALANCE. 
 
 fulcrum, bearing upon an agate plane throughout its whole 
 length; whereas in the other balances the whole weight is 
 supported by portions only of the knife-edge, amounting 
 together to one-tenth of an inch. The supports for the scales 
 are knife-edges, each six-tenths of an inch long. These are 
 each furnished with two pressing screws, by means of which 
 they may be made parallel to the central knife-edge. 
 
 "Each end of the beam is sprung obliquely upwards and 
 towards the middle, so as to form a spring through which a 
 pushing screw passes, which serves to vary the distance of 
 the point of suspension from the fulcrum, and, at the same 
 time, by its oblique action, to raise or depress it, so as to fur- 
 nish a means of bringing the points of suspension and the 
 fulcrum into a right line. 
 
 " A piece of wire, four inches long, on which a screw is cut, 
 proceeds from the middle of the beam downwards. This is 
 pointed to serve as an index, and a small brass ball moves on 
 the screw, by changing the situation of which the place of the 
 centre of gravity may be varied at pleasure. 
 
 " The fulcrum, as before remarked, rests upon an agate 
 plane throughout its whole length, and the scale-pans are 
 attached to planes of agate, which rest upon the knife-edges, 
 forming the points of support. This method of supporting 
 the scale-pans, we have reason to believe, is due to Mr. 
 Cavendish. Upon the lower half of the pillar, to which the 
 agate plane is fixed, a tube slides up and down by means of 
 a lever which passes to the outside of the case. From the 
 top of this tube, arms proceed obliquely towards the ends of the 
 balance, serving to support a horizontal piece, carrying at 
 each extremity two sets of Ys, one a little above the other. 
 The upper Y s are destined to receive the agate planes to 
 which the scale-pans are attached, and thus to relieve the 
 knife-edges from their pressure ; the lower to receive the 
 knife-edges themselves, which form the points of suspension 
 of the pans, consequently these latter Ys, when in action, 
 sustain the whole beam. 
 
 " When the lever is freed from a notch in which it is lodged, 
 a spring is allowed to act upon the tube we have mentioned, 
 and to elevate it. The upper Ys first meet the agate planes 
 carrying the scale-pans, and free them from the knife-edges. 
 The lower Ys then come into action and raise the whole 
 beam, elevating the central knife-edge above the agate plane. 
 
BERLIN BALANCE. — TRALLE'S BEAM. 
 
 95 
 
 This is the usual state of the balance when not in use : when 
 it is to be brought into action, the reverse of what we have 
 described takes place. On pressing down the lever, the cen- 
 tral knife-edge first meets the agate plane, and afterwards 
 the two agate planes, carrying the scale-pans, are deposited 
 upon their supporting knife-edges. 
 
 " A balance of this construction was employed by Captain 
 Kater, in adjusting the national standard pound. With a 
 pound troy in each scale, the addition of one-hundreth of a 
 grain caused the index to vary one division, equal to one- 
 tenth of an inch; and Mr. Robinson adjusts these balances 
 so that with one thousand grains in each scale, the index 
 varies perceptibly on the addition of one-thousandth of a grain, 
 or of one-millionth part of the weight to be determined." 
 
 A balance of this or the preceding kind, necessarily costly 
 ($85 to $100) from the great care required in its construc- 
 tion, is only needed for the weighing of minute quantities of 
 matter in scientific researches, and where it is desirable to 
 estimate the least appreciable difierences of weight. An in- 
 strument well calculated for all the ordinary purposes of 
 analysis, is the Berlin balance. Fig. 52. 
 Those manufactured by E. N. Kent, New 
 York, are guaranteed, when loaded with 
 50 grammes in each pan, to turn with 
 •005 grammes, or yu-ooo*^ P^^* ^^ *^® 
 weight. Its cost, with an extra pan for 
 taking the specific gravity of bodies, and 
 glass case, containing a drawer with divi- 
 sions to receive the different parts of the 
 balance, and thus render it portable, is 
 thirty dollars. 
 
 In many processes, and, indeed, in some few instances of 
 analysis, for example of gold ores and of vegetable matters, one 
 or more constituents of which are only obtainable, even in 
 minute quantities, from large amounts of the material, it is 
 necessary to have a second balance calculated to weigh from a 
 quarter of an ounce to five pounds with such precision that 
 one or two grains will turn the dish when loaded with its 
 greatest weight. Fig. 53 represents a balance of this kind, 
 made after a Tralles beam, by DufFey, of this city. It con- 
 sists of two brass dishes, A A, suspended by loops, D D, 
 which rest upon the steel knife-edges at the extremities of the 
 
 Fig. 52. 
 
 / \ 
 
 aI/ 
 
 1 
 
 
 /kiJ t^ id 
 
 ^ 
 
 
 I °- — ^ 
 
 
96 
 
 PRESERVATION OF THE BALANCE. 
 
 beam C. The beam is supported by the knife-edge in its 
 centre as at E, and the whole balance is suspended to an up- 
 right, crooked at its top, by the hanger B. Annexed to the 
 centre of the beam is a long vertical needle, which, following 
 the vibrations of the beam, serves to indicate the least oscil- 
 lation, which is rendered more perceptible by an ivory seg- 
 
 Fig. 53. 
 
 ment situated behind its point, and divided into degrees. 
 This balance is placed in the room D, PI. 2, upon the table 
 adjoining that upon which is the finer balance. The support 
 to which it is suspended may be either of wood or metal. To 
 prevent damage to the knife-edges, the dishes, when the 
 scales are not in use, should be unhung, and the whole balance 
 kept covered with a linen cover, distended over a wire frame 
 work, which may be suspended by a cord upon a pulley, and 
 counterpoised so as to admit of being readily raised or lowered. 
 Preservation of the Balances. — Each of the finer balances 
 should have a separate table, and these tables a permanent 
 position in a close, well-lighted room, expressly appropriated 
 for the purpose. The top of the table must be of hard wood 
 and perfectly horizontal ; and to secure the table itself 
 against the slightest jarring motion, it may be tightly fastened 
 to the floor by iron clamps and screws fitted to its legs. Great 
 
PRESERVATION OP THE BALANCE. 97 
 
 care is requisite to have it plumb. Of the two drawers which 
 it should contain, one is for the spatulas, spoons, crucible 
 tongs, papers, watch glasses, and other implements used in 
 weighing ; the other may be fitted deskwise, and furnished 
 with slips of paper, or a porcelain slate and pencil, to aflFord 
 convenience in recording the weights. A polished cast-iron 
 slab about six inches square, upon which to set the heated 
 crucibles and promote their cooling by conducting off the 
 excess of heat previous to weighing, may be considered a 
 necessary accompaniment to the table. In order to preserve 
 its brightness, it should be encased in a woolen bag and kept 
 within the drawer when not in use ; or it may be enclosed in 
 a frame with a sliding cover, and fastened to the top of the 
 table near to one of its corners. The cover which protects its 
 surface from oxidation can readily be drawn out whenever it 
 is required to use the slab. 
 
 It is not sufficient for the preservation of the delicacy of 
 the balances, that the room in which they are kept should be 
 dry and tight. Vapors, aqueous and corrosive, will in divers 
 ways find entrance into the apartment, and so, therefore, be- 
 sides the precaution of lacquering the brass and steel parts of 
 the balance, the instrument should be enclosed in a sufficiently 
 capacious mahogany or walnut case, with sash doors in the 
 front and back, and sash windows at either side. The doors 
 should be always kept closed and fastened by their buttons 
 when the balance is not in use, else the entrance of dust and 
 moisture will impair its accuracy. An additional and very 
 efiectual precaution against oxidation by moisture, is to keep 
 constantly within the case a capsule containing some ab- 
 so'rbent matter, as fused chloride of calcium or carbonate of 
 potassa. By an occasional renewal of the absorbent matter, 
 the atmosphere within the case can be kept very dry. The 
 multiplication of door- ways is to afford facility for the passage 
 and weighing of long tubes, which have to be placed across 
 the pan. The divisions in the drawer at the bottom of the 
 case must be lined with velvet, and so arranged as to receive 
 the different parts of the balance, and allow its transportation 
 without the least risk of damage. 
 
 In order to preserve the edges of the knives, the beam 
 should always be thrown out of action when the balance is 
 not in use, otherwise their constant contact with the planes 
 and the pressure of the balances, as well as the sudden 
 
98 THE BALANCE — THE WEIGHTS. 
 
 addition of a heavy weight, will injure their delicacy. 
 Duffy's support, with its thumb lever outside, before men- 
 tioned, affords a means of not only preventing these contin- 
 gencies, but also of communicating motion to the beam, without 
 the necessity of opening the doors, and consequent exposure 
 of the balance. 
 
 The three or four feet upon which the case rests have screws 
 passing through them. These serve to give the balance a per- 
 fectly horizontal position, even upon an uneven surface — the 
 level being obtained by raising or depressing either of the 
 screws, as the case requires, and as will be indicated by the 
 two spirit levels which should be fitted to the pedestal of each 
 balance. 
 
 The position of the balance should be with due regard to 
 light, but while placed near the window, to afford facility in 
 perceiving the slightest oscillations of the needle, it should be 
 free from any sudden actions of the solar rays, which, by pro- 
 ducing unequal expansion of the different parts would occasion 
 inexact results in weighing. 
 
 The balances should be cleansed and adjusted whenever 
 they have become inaccurate, for it is almost impossible for 
 even the best balance to retain its sensitiveness indefinitely. 
 This work should rather be confided to a manufacturer of 
 balances, as it requires both skill and experience. Slight 
 discrepancies in the weight of the two dishes can be tempo- 
 rarily compensated for by adding to that dish which is defi- 
 cient, sufficient weight to restore its equilibrium. 
 
 CHAPTER VI. 
 
 THE WEIGHTS. 
 
 There are three sets of weights requisite, of which, one for 
 the common scales of the operating room should be avoirdu- 
 pois, and range from eight or more pounds downward to an 
 ounce or less. These weights are for the rougher operations 
 of weighing, and may be of cast iron, with a coating of black 
 japan to protect them against oxidation. 
 
THE BALANCE — THE WEIGHTS. 99 
 
 For the second balance (Fig. 52) the weights must be of 
 brass, in the form of short cylinders/, Fig. 56, with knobs at the 
 top, and should range from 25,000 to 10 grains, decreasing by 
 fives, in the series to 500, as follows: 25,000, 20,000, 15,000, 
 10,000, 5000, 1000, 500; and from that point in ratio as fol- 
 lows: 400, 300, 200, 100, 50, 30, 20, 10, so as to make alto- 
 gether 15 weights; the whole to be enclosed in a suitable box 
 with a hinged cover. 
 
 These latter weights, though required to be accurately ad- 
 justed, are not necessarily so nicely precise as those for the 
 analytic balances (Figs. 47, 50). They should always be sub- 
 divided after the decimal system, so that ten of the smaller 
 weights will make one of the next highest class. This arrange- 
 ment (so that they perfectly agree with each other of the same 
 denomination) will render it unimportant whether they be grain 
 or French gramme weights, the two kinds almost exclusively 
 used in scientific research. 
 
 If they are grain weights, the series should range from 
 5000 grains to jo^oo*^ ^^ ^ grain, as follows: — 5000, 3000, 
 2000, 1000, 500, 300, 200, 100, 50, 30, 20, 10, 5, 3, 2, 1, 
 .1, .2, .3, .5, .05, .03, .02, .01, .005, .003, .002. The gramme 
 weights range from one centigramme to one milligramme. 
 The divisions of the gramme (the standard unit of the French 
 weights) are the decigramme = j^^th gramme; the centigramme 
 = y J^th gramme; the milligramme = j^QQth gramme. Its 
 multiples are the decagramme = 10; the hectogramme =i 100; 
 the kilogramme = 1000 ; and the mp^iagramme = 10,000 
 grammes. The table below shows the relative value and pro- 
 portions of the French decimal and troy and avoirdupois 
 weights. 
 
 Metrical or Decimal Weights. 
 
 
 
 
 Equiv. in Troy 
 
 Equiv. in avoirdupois 
 
 Names. 
 
 Equlv. in grammes. 
 
 grains. 
 
 weight. 
 
 
 
 
 
 lbs. oz. grs. ■■ ' • 
 
 Milligramme 
 
 
 .001 
 
 .0154 
 
 ', 
 
 Centigramme 
 
 
 .01 
 
 .1543 
 
 
 Decigramme 
 
 
 .1 
 
 1.5434 
 
 / 
 
 Gramme 
 
 
 1. 
 
 • 15.434 
 
 ^ '• 
 
 Decagramme 
 
 
 10. 
 
 154.3402 , 
 
 . ■.• Oi 45w o . • 
 
 Hectogramme 
 
 
 100. 
 
 1543.4023 , 
 
 3^.! 2.1^2 
 
 Kilogramme, or 
 
 Kilo 
 
 1000. 
 
 15434.02:>4 ^ 
 
 2 3} l,2;r73 
 
 Myriagramme 
 
 
 10000. 
 
 154340.2344 
 
 22 0| u2. 
 
 All of the weights for the fine Oalance must be adjusted 
 
100 THE BALANCE — THE WEIGHTS. 
 
 with the nicest accuracy, and before being used should be 
 compared with others of attested correctness. Of the French 
 weights those from the milligramme to the gramme should be 
 of platinum; and so, also, of the grain weights, those from the 
 ten grain weight downwards should be of the same metal. 
 Palladium being of but half the specific gravity of platinum, 
 and similar to it in other respects, is sometimes used for the 
 fractional grain weights, because of the greater relative sur- 
 face which it presents. The remaining larger weights, to save 
 expense, may be of brass, and, to preserve them from oxida- 
 tion, should either be covered with a thin coat of lacquer or 
 else galvanized with gold or platinum. 
 
 Each set should contain duplicates of the 10, 2 and 1 grain 
 weights; triplicates of the .2, .1, .02, .01, and quadruplicates of 
 the .001 grain weights; in many instances, especially in taking 
 specific gravities, these additional weights are indispensable. 
 
 In order to preserve the weights free from dust and oxida- 
 tion, they must be encased in a close box with hinged cover 
 and fastenings. The interior of the box is divided into com- 
 partments, lined with velvet to prevent abrasion of the sur- 
 faces of the weights, each of which should have a separate 
 division. The edges of every compartment should be marked 
 in ink with the value of the weight it contains ; and the weights 
 themselves must have their denominations stamped upon them. 
 The series must be so accurately adjusted, that the difference 
 between any one of the large weights and the combined num- 
 ber of smaller ones, equal to it, shall not be perceptible in a 
 balance turning with one-tenth of a milligramme. 
 
 To test their accuracy, take any two of them of the same 
 denomination, convey them, with the fork or forceps, to the 
 balance, and place one in each dish. If the beam upon being 
 put in action is in perfect equilibrium, the weights are uni- 
 form, and can serve as standards. Now, for further verifica- 
 tion, place both together in one dish, and in the opposite pan 
 add enough of smaller weights to equal that of the two com- 
 bined. If the beam still retains its equilibrium, when put in 
 action, the weights may be considered correct. 
 '"As Treqiient' /'handling of the weights with the fingers 
 wouM* ta.rnish th^m] and otherwise injure their value, a small 
 fork and" ?.'pair of fr»rc6ps are necessary accompaniments to 
 each set of weights. " The, fork, represented by Fig. 54, made 
 of either ivory, horn or wood,und being intended for raising 
 
THE BALANCE — THE WEIGHTS. 
 
 101 
 
 the brass weights, has its notches at either end of different size, 
 so as equally to accommodate the knobs of 
 both the larger and smaller weights. A Fig- ^4. Fig. 55. 
 small pair of elastic forceps, Fig. 55, of 
 brass or plated, or polished steel, with 
 platinum, or ivory points, serve for the 
 smaller platinum weights, which, for con- 
 venience of handling, should be turned up 
 at one corner, as at g, Fig. 56. 
 
 The box should be closed after each 
 weighing, and, to preserve it from the cor- 
 rosive vapor that may be floating about, 
 should be kept in the drawer of the balance table. 
 
 Fig. 56, represents a box of weights and all the necessary 
 
 Fig. 56. 
 
 '?^ 
 
 ^ 
 
 appurtenances. The ribs a a a, fitted to the interior of the 
 top, by pressing against them when the box is closed, keep 
 the weights in their places. The fork and forceps are shown 
 in place at b h. The channel d, kept always covered with a 
 thick glass plate, contains the platinum weights, an extra 
 quantity of the smaller of which are kept in the cavity e. 
 These cases and the weights, accurately adjusted and finely 
 finished, can be purchased of either Kent or Duffey. 
 
 Small weights, to supply the place of such as may be acci- 
 dentally lost, can be made by first determining the weight of 
 a given length of wire of uniform thickness throughout, and 
 then dividing it into perfectly equal parts ; — the number of 
 the divisions indicates the fraction of the original weight which 
 they represent as a whole ; for instance, if the wire weighed 
 ten grains; and is divided into 10 or 20 portions, each frac- 
 tion will represent a grain or half grain, accordingly. By 
 
102 THE BALANCE — WEIGHING. 
 
 using wire of greater thickness, weights of augmented value 
 can, in like manner, be made and adjusted. 
 
 Shot, of which there should be a box of the several sizes 
 kept in the balance table-drawer, are convenient counterpoises 
 for tubes, capsules, crucibles, watch glasses, and other recepta- 
 cles for substances to be weighed. 
 
 CHAPTER VII. 
 
 WEIGHING. 
 
 There are certain preliminaries to be observed in all deli- 
 cate weighing operations, of which the most important is to 
 ascertain whether the balance is in order, as regards equili- 
 brium and freedom of oscillation. To do this, each dish should 
 be loaded nearly to the full extent of the power of the balance. 
 If, when the beam is put in action, there is no perceptible va- 
 riation in the dishes, the equilibrium is perfect. For further 
 verification, there should be an exchange of loads, from one 
 dish to the other, and the beam again set in motion. The 
 recovery of the equilibrium, after the cessation of the vibra- 
 tions indicates the correctness of the balance. The need of 
 more than a milligramme for the analytic balance, or of y'^th 
 of a milligramme in the more delicate balance, to restore a 
 deficiency in either dish, should condemn the instruments for 
 quantitative examinations, unless previously adjusted. This 
 is done by the addition of bits of tin-foil to that dish which is 
 lightest. When, however, the balance is carefully used, and 
 by but one operator, it will be only necessary to reassure him- 
 self of its equilibrium in those weighings where absolute accu- 
 racy is all important. Be careful, however, in adjusting, as 
 well as in weighing, that the weights in the pan do not over- 
 load the balance and make it set^ an efi'ect the more prompt, 
 in proportion to the greater accuracy and sensibility of the 
 balance. The setting, which makes one scale appear heavier 
 than the other, is a permanent depression of the lowest pan 
 by the slightest impulse to the exactly horizontal beam of a 
 
THE BALANCE — WEIGHING. 103 
 
 surcharged balance. Hence the necessity of loading the ba- 
 lance within the limit of its maximum power. 
 
 In all weighing operations, the counterpoising of substances 
 is more speedily attained, and with less injury to the balance, 
 by systematically following a weight, which is removed from 
 the pan as too heavy, by the next in succession, until equili- 
 brium is obtained. Thus, in balancing a watch glass, if the 
 50 grain weight drags the beam, replace it by the 15 ; if this 
 is still too much, use the 10 weight ; and if this is too little, 
 make up the deficiency with the smaller weights, added con- 
 secutively, and decreasing gradually their denomination as the 
 counterpoise is approached. 
 
 To preserve the accuracy of the balance, it should be put 
 out of action upon every addition, removal, or substitution of 
 weights. As a precaution against error, the weights must 
 always be removed from the pan and spread upon white paper 
 to be counted; and to verify the aggregate, in putting them 
 away, their denominations should also be compared with their 
 value, as marked upon the vacancies which they occupy in the 
 box in which they are kept. The slips of paper and porce- 
 lain slate, in the table-drawer, serve to make notes of their 
 amount, which should be done before placing them in the box. 
 
 A provision against inaccuracy, from very slight inequality 
 of the arms of the beam or imperfect equilibrium from other 
 causes, is the invariable use of the same pan for the reception 
 of the substance to be weighed. By this practice, notwith- 
 standing the difference in the weights of the two dishes, the 
 ratio being kept uniform, the quantities will be proportionably 
 augmented or decreased, so that the products of analyses can 
 be as accurately estimated as in a perfect balance. An alter- 
 nate use of the pans for the weights and the substance to be 
 weighed, will, on the contrary, lead to results too high or low, 
 as the case may be. We, however, obtain, in this way, only 
 the relative weight of the substance, and not its absolute weight, 
 which requires a perfect balance. 
 
 Borda proposes to avoid the errors of inaccurate balances, 
 by first taking the tare of the substance with that or any other 
 counterpoise, and afterwards substituting, in its stead, weights 
 sufficient to restore the equilibrium, which was disturbed by 
 its withdrawal from the dish. The sum of these added weights 
 represent exactly that of the substance being weighed. This 
 
104 WEIGHING OF SOLIDS. 
 
 mode is termed double weighing, and affords very nice results 
 even in balances with disproportioned beams. 
 
 A modification of the above method is, supposing, for in- 
 stance, that five grains of a substance are required, to place 
 twenty grains' weight in one dish, and a small capsule in the 
 other, and then to establish equilibrium by adding, to the lat- 
 ter, the requisite number of very fine shot. This done, remove 
 15 grains from the first dish, and introduce into the capsule 
 sufficient of the substance, to be weighed, to compensate for 
 their loss. 
 
 Weighing of Solids. — The balance being in perfect order 
 and repose, the next step is to counterpoise the vessel in which 
 the substance, which should in no instance be placed upon the 
 naked dish, is to be weighed. Circular disks of highly glazed 
 paper are sometimes used as recipients, but being attractive 
 of moisture, are preferably replaced by a watch glass or cru- 
 cible of platinum or of porcelain. The recipient being placed 
 upon the pan, appropriated exclusively for the purpose, is 
 then accurately counterbalanced by shot or fragments of me- 
 tal. In analyses, the counterpoise must be preserved for 
 future references. They may be either wrapped in paper 
 or enclosed in paper pill-boxes, but in either case must be 
 labelled. In delicate analyses, to avoid error, the tare of the 
 vessel should be estimated in weights, and their amount im- 
 mediately noted down, to be afterwards subtracted from the 
 combined weight of it, and the substance weighed. The tare 
 of the drying tubes, or of Liebig's and other apparatus used 
 in organic analysis requiring to be weighed, to prevent mis- 
 takes, should be labelled upon the implements themselves 
 with which it corresponds. This done, the substance is in- 
 troduced into the recipient, if in lumps, by means of a pair 
 of forceps with platinum points; if in powder, with an ivory, 
 horn, or platinum spoon or spatula, accordingly as it may be 
 inert or corrosive. The blade of the spatula should never be 
 of steel, as it is so liable to oxidation. A slip of very thick 
 sheet platinum, one inch in width and two inches long, fast- 
 ened in a wooden or metallic handle, is generally used. Its 
 usefulness for this purpose may be increased by alloying it 
 with a very minute portion of silver, which increases its elasti- 
 city in an eminent degree. The weights are added to the 
 opposite dish, and always after throwing the beam out of 
 action, through the side door of the case, which must be im- 
 
WEIGHING OF COEROSIVE SUBSTANCES. 105 
 
 mediately closed after each addition. If, when the balance is 
 lifted from its supports, by depressing the thumb lever 
 extending without the case, the index needle turns rapidly 
 towards the dish opposite to the weights, the balance must be 
 put in repose, another weight added, and the motion of the 
 needle again examined. This operation should be repeated 
 upon the addition of each weight, however small. As the 
 pans approach equilibrium, the vibrations of the needle de- 
 crease in rapidity, and a little experience and observation 
 will enable one to hit the right point after one or two trials. 
 When any given quantity of a substance is to be weighed, the 
 requisite weight should be placed in the dish first, and the sub- 
 stance if in powder deposited in the other dish with a spoon 
 or spatula, until an accurate counterpoise is obtained, taking 
 care however, to bring the balance at rest upon each addi- 
 tion of material, which may be made to fall in very minute 
 quantities from the spatula by gently tapping against its 
 handle with the finger. 
 
 Those substances which are hygrometric, should be weighed 
 in a covered vessel; for instance, between two watch glasses, 
 or in a small tube with a ground stopper, which may be held 
 in an upright position by a twine loop slipped over the sus- 
 pending wire of the pan, or by a cork and wire stand, as 
 shown by Fig. 57. 
 
 The more delicate balances have for this purpose, for that 
 of organic analysis and of weighing substances in water, 
 a supplementary pan, with a hook beneath, for convenience 
 of suspension. This pan, which descends from the beam 
 only one-half the distance of the other, is shown by Fig. 62. 
 
 After the weighing is completed, the weights, as before 
 directed, are withdrawn with forceps, placed upon a piece 
 of white paper, and their several amounts added together ; — 
 the total gives the weight of the substance in the opposite 
 dish. 
 
 Covered vessels are also requisite for those corrosive sub- 
 stances the exhalations from which would be injurious to the 
 balance, and impair its accuracy. 
 
 Substances should never be weighed whilst hot, even in 
 closed vessels, otherwise the ascending current of air thus 
 produced, together with an unequal expansion of one arm of 
 the beam, will give inaccurate results. A crucible, therefore, 
 which has been over the lamp for the ignition of its contents, 
 8 
 
106 WEIGHING OP LIQUIDS. 
 
 should be first cooled by standing upon the iron slab accom- 
 panying the balance table, otherwise its hot weight, not cor- 
 responding with its cold weight, would, in estimating the re- 
 sult, lead to an error in the real weight. 
 
 Weighing of Liquids. — The nature of liquids, especially 
 their temperature and volatility, have an important influence 
 upon the precision of the results. 
 
 Non-volatile liquids may be weighed in a counterpoised 
 capsule, watch glass, flask or tube. Those vessels which have 
 spherical bottoms are supported in the pans upon cork rings, 
 which are readily made by hollowing out a cork and bevelling 
 its upper edges interiorly. If the recipient is tall, it requires 
 a stand to maintain it in an upright position. 
 Fig. 57. This stand, shown by Fig. 57, is nothing more 
 f=^ than a disk of cork 5, with the wire catch a, fast- 
 
 ened to it. An excellent substitute, is a broad 
 cork, with a hole in its centre, corresponding with 
 the size of the tube, and bored smoothly and 
 nearly through the cork with the cork-borer here- 
 after to be described. The use of the twine loop, 
 before mentioned, is less safe and convenient for 
 suspending these vessels. 
 
 The liquids are conveyed to the recipients in dropping 
 tubes or pipettes. This mode allows their gradual addition, 
 and in small quantities. The pipette, for small quantities, is 
 nothing more than a tube of a quarter inch diameter, 
 Fig. 58. drawn out at its lower end, as shown by Fig. 58. 
 The tapering end of this tube, being placed in the 
 liquid, as soon as the latter has risen, interiorly to 
 its external level, place the thumb upon the upper 
 orifice of the pipette, withdraw it from the liquid, 
 and convey it to the counterbalanced recipient in the 
 scale dish. Holding it immediately over this reci- 
 pient, you then remove the finger and allow the liquid 
 to be driven out by atmospheric pressure, either in 
 a thin stream or drops, according as the capillary 
 orifice of the thin end of the pipette is larger or smaller. 
 Remember that, as pressure of the surrounding fluid is the 
 cause of the liquid's ascension into the tube, its ingress is 
 proportional to the depth to which the pipette enters the 
 containing vessel. 
 
 When the pipette contains more liquid than the required 
 
WEIGHINa OF LIQUIDS: — PIPETTES. 
 
 107 
 
 quantity, the flow can be arrested as soon as the given weight 
 is counterbalanced, by quickly replacing the finger upon the 
 upper orifice of the tube. After removing it from over the 
 pan, the surplus can be emptied into the original vessel. 
 
 Any excess of the liquid, preventing a perfect adjust- 
 ment, may be removed from the recipient with an empty 
 pipette in the same manner as it was introduced. With a 
 little precaution in the management of the pipette, the flow 
 may be made so gradual that it can be arrested as soon as the 
 vessel has received the required quantity. The insertion of 
 slips of bibulous paper serves to withdraw any slight excess, 
 unless the liquid is corrosive and acts upon paper, in which 
 case, a glass rod must be substituted. The insertion of this 
 rod into the liquid, and its subsequent withdrawal, causes a 
 loss thereto of the small adherent quantity, and thus we have 
 a means of accurately weighing any required quantity of 
 liquid. 
 
 If the quantity of liquid to be weighed is large, the 
 form of the pipette must be as shown by 
 Fig. 59. The bulb in its centre serves as a re- 
 servoir for the required charge. If the nature 
 of the liquid does not render the operation dis- 
 agreeable to the manipulator, the pipette may 
 be quickly filled by suction with the mouth. 
 This plan, however, is objectionable, as being 
 liable to introduce moisture. A much better 
 method is to cover tightly the larger or upper 
 end of the pipette with a caoutchouc bottle. 
 By compressing this bottle with the hand, a 
 partial expulsion of air ensues, and the liquid, 
 into which the pipette is plunged, rushes in 
 quickly to fill the vacuum. The bottle, being 
 again distended by the upward pressure of the 
 interior atmosphere, prevents the exit of any 
 drop of liquid, until it is forced out by com- 
 pressing the bag a second time. 
 
 Some chemists prefer pipettes of syringe con- 
 struction, Fig. 60. Like the afore-mentioned, they must be 
 invariably of glass. The liquid is drawn from its original 
 container by immersing the taper end therein, and raising the 
 piston; — the liquid mounts into the cylindric reservoir until 
 filled. The depression of the piston, by the pressure of the 
 
■^ s 
 
 Y 
 
 108 WEIGHING OF GASES. 
 
 finger upon the top of the handle, causes the exit of the liquid 
 with rapidity proportional to the power applied. 
 
 The stock of pipettes should consist of several 
 y go sizes. After being used, they should be carefully laid 
 ^^ across a porcelain plate, there to remain until the 
 completion of the weighing, when they must be well 
 rinsed out previous to being returned to their places 
 in the drawers. 
 
 All volatile substances must be weighed in small, 
 closely stoppered flasks, tubes or other vessels, pre- 
 viously counterpoised. To insure accurate results, 
 care must be taken that the temperature does not 
 favor volatilization. Fuming liquids should, if possi- 
 ble, be measured. 
 
 To preserve the balance, as much as possible, from 
 their corrosive action, the recipient should be removed 
 from the pan upon each addition or withdrawal of any 
 portion of its charge, and tightly closed again before 
 being returned. The slender tube. Fig. 99, for small 
 quantities, and the syringe for larger proportions, 
 are the proper implements for conveying the liquids to the 
 balance. 
 
 Very deliquescent substances, such as are not checked in 
 their liquefying tendency by the greatest practicable dryness 
 of the balance case, and are not alterable by water, should be 
 weighed in solution. First, pour in a sufficiency of water in 
 the counterpoised recipient and note its weight. The increase 
 of weight given to this water by the addition of the deliques- 
 cent body, is the actual weight of the latter, and the solution 
 can be used in the analysis instead of the solid. In some 
 instances, according to the nature of the substance, alcohol 
 may be substituted for water. 
 
 Weighing of Gases. — In weighing gases, it is necessary, in 
 order to obtain nice results, to guard against the least varia- 
 tions of temperature, pressure, and humidity of the atmo- 
 sphere. Gases are readily estimated by means of a very sen- 
 sitive balance, though the old plan, by measurement of volume 
 in graduated vessels, is accurate and easily executed. 
 
 Gases are weighed in counterpoised balloons, which must be 
 thoroughly cleaned and dried, and wiped exteriorly and inte- 
 riorly, so as to remove every particle of grease, dirt or dust. 
 The balloon is then to be connected by a coupling cock fitted 
 
WEIGHING OP GASES. 109 
 
 to its neck, with an air-pump (Fig. 32) or syringe, and ex- 
 hausted of its air. To insure the expulsion of all remnants 
 of gas from a former weighing, the balloon should be subjected 
 to repeated alternate exhaustions and airings. The exhausted 
 balloon is then to be attached to a graduated bell-glass, also 
 fitted with a coupling cock, as shown by Fig. 61. This bell- 
 glass is the reservoir of the gas which is received or 
 collected over {see Pneumatic Trough) water or mer- Fig. 6i. 
 cury ; the latter fluid, giving more exact results, is 
 used for those gases which are soluble in the former. 
 Communication between the balloon and bell-glass, 
 being made by opening their connecting cocks, the 
 gas rushes from the latter into the former by force 
 of atmospheric pressure upon the mercury. When 
 the balloon is filled, the flow is to be stopped by 
 closing the cocks. A delay of several minutes is 
 necessary [see Measurement and Transfer op 
 Gases) to allow the temperature within the bulb to 
 become that of the external air, that the level within 
 and without the bell-glass may be equalized, and the 
 quantity of gas noted. The balloon must then be fefr"^ . 
 detached, and again weighed with care and accu- 
 racy. The difi'erence between its present and original weight, 
 is that of the volume of gas which it contains. 
 
 In the weighing of gases, it is indispensable to note the 
 temperature and barometric pressure, and to observe all other 
 conditions and precautions requisite in the Measurement of 
 Gases. 
 
 Those gases which are without action upon mercury, ought 
 to be collected over that metal, for most gases, by contact 
 with water, absorb more or less of its vapor, according to the 
 temperature, and, therefore, to insure correct results, it is 
 generally preferable to purify the gas of moisture previous to 
 weighing it. This is done by passing it through a tube {see 
 Desiccation of Gases) containing fused chloride of calcium, 
 or some other absorbent substance. 
 
 It must be recollected, however, in the desiccation of gases, 
 by transit through tubes containing absorbent matter, that 
 the quantity of dry gas, entering into the globe, is less than 
 that received from the bell-glass, the volume of vapor ab- 
 stracted in its passage. To determine the amount of this loss, 
 " observe the temperature of the moist gas, and correct its 
 
110 
 
 WEIGHING OF GASES. 
 
 volume by the pressure of thirty inches of mercury. Then, 
 by the table below, ascertain the proportion of vapor which 
 was present in the volume which left the jar, and subtract 
 it from the corrected volume; — the remainder will be the 
 volume of dry gas which has entered the globe." 
 
 The table, taken from Faraday, "exhibits the proportion 
 by volume of aqueous vapor existing in any gas standing over 
 or in contact with water, at the corresponding temperatures, 
 and at mean barometric pressure of thirty inches." 
 
 40° — 
 
 .00933 
 
 51° — 
 
 .01380 
 
 61° — 
 
 .01923 
 
 71° — 
 
 .02653 
 
 41 — 
 
 .00973 
 
 52 — 
 
 .01426 
 
 62 — 
 
 .01980 
 
 72 — 
 
 .02740 
 
 42 — 
 
 .01013 
 
 53 — 
 
 .01480 
 
 63 — 
 
 .02000 
 
 73 — 
 
 .02830 
 
 43 — 
 
 .01053 
 
 54 — 
 
 .01533 
 
 64 — 
 
 .02120 
 
 74 — 
 
 .02923 
 
 44 — 
 
 .0:093 
 
 55 — 
 
 .01586 
 
 65 — 
 
 .02190 
 
 75 — 
 
 .03020 
 
 45 — 
 
 .01133 
 
 56 — 
 
 .01640 
 
 66 — 
 
 .02260 
 
 76 — 
 
 .03120 
 
 46 — 
 
 .01173 
 
 57 — 
 
 .01693 
 
 67 — 
 
 .02330 
 
 77 — 
 
 .03220 
 
 47 — 
 
 .01213 
 
 58 — 
 
 .01753 
 
 68 — 
 
 .02406 
 
 78 — 
 
 .03323 
 
 48 — 
 
 .01253 
 
 59 — 
 
 .01810 
 
 69 — 
 
 .02483 
 
 79 — 
 
 .03423 
 
 49 — 
 
 .01293 
 
 60 — 
 
 .01866 
 
 70 — 
 
 .02566 
 
 80 — 
 
 .03533 
 
 50 — 
 
 .01333 
 
 
 
 
 
 
 
 This table is also useful for determining that part of the vo- 
 lume and weight of a moist gas, due to aqueous vapor after it 
 has been weighed without previous desiccation, for as it " in- 
 cludes any temperature at which gases are likely to be weighed, 
 the proportions in bulk of vapor present, and consequently of 
 the dry gas, may easily be ascertained. For this purpose the 
 observed temperature of the gas should be looked for, and 
 opposite to it will be found the proportion in bulk of aque- 
 ous vapor at a pressure of 30 inches. The volume to which 
 this amounts should be ascertained and corrected to mean 
 temperature. Then the wliole volume is to be corrected to 
 mean temperature and pressure and the corrected volume of 
 vapor subtracted from it. This will leave the corrected vo- 
 lume of dry gas. It has been ascertained, in a manner ap- 
 proaching to perfect accuracy, that a cubic inch of perma- 
 nent aqueous vapor corrected to the temperature of 60°, 
 and a mean pressure of 30 inches, weighs 0.1929 grains. 
 The weight, therefore, of the known volume of aqueous vapor 
 is now easily ascertained, and this being subtracted from the 
 weight of the moist gas, will give the weight of the dry gas, 
 the volume of which is also known. 
 
 "As an illustration, suppose a gas standing over water 
 had been thus weighed, and that 220 cubic inches at the 
 
WEIGHING OF GASES. Ill 
 
 temperature of 50° Fahr., and barometric pressure of 29.4 
 inches had entered into the globe and caused an increase in 
 weight of 101.69 grains. Bj reference to the table it will 
 be found that at the temperature of 50°, the proportion of 
 aqueous vapor in gas standing over water is .01333, which in 
 the 220 cubic inches will amount to 2.933 cubic inches, which 
 corrected to the temperature of 60°, becomes 2.942 cubic 
 inches. The whole volume corrected to mean temperature 
 and pressure will be found to equal 219.929 cubic inches, 
 from which, if the 2.942 cubic inches of aqueous vapor pre- 
 sent be subtracted, it will leave 216.987 cubic inches as the 
 volume of dry gas at mean temperature and pressure : 2.942 
 cubic inches of aqueous vapor weigh .5675 grains, for 2.942 
 X 0.1929= 0.5675; this subtracted from 101.69, the whole 
 weight, leaves 101.1225 grains, which is the weight of the 
 216.987 cubic inches of dry gas; and by the simple rule of 
 proportion, therefore, it will be found that 100 cubic inches 
 of such gas, when dried and at mean temperature and pres- 
 sure, will weigh 46.603 grains. 
 
 ^' It is not necessary in this experiment that the globe or 
 flask be perfectly exhausted of air before the gas be admit- 
 ted, all that is necessary in that respect being, that the quan- 
 tity of gas which enters, and the corresponding increase of 
 weight, be known. For the same reason it is not necessary 
 that the globe be filled, provided the quantity which does 
 enter is ascertained upon the graduation of the jar when the 
 level is the same inside and outside; and that no alteration 
 of the quantity in the globe be allowed before the weighing 
 is completed. The state and quantity of the gas are estimated 
 in the jar, and it is there that the temperature and pressure 
 should be attended to. It is essentially necessary that the 
 temperature of the globe over the water should have been 
 steady for some time before the experiment be made, and 
 that it do not change until the gas has entered the globe and 
 the stop-cock is securely closed. After that, a little varia- 
 tion of temperature is of no consequence, so that nothing 
 passes into or out of the globe until the conclusion of the 
 experiment. The globe, as before said, should be clean and 
 dry." 
 
112 DETERMINATION OF SPECIFIC GRAVITY. 
 
 CHAPTER yill. 
 
 THE DETERMINATION OF SPECIFIC GRAVITY. 
 
 Bodies which are of uniform bulk may vary in density, and 
 thus give rise to a difference in their specific gravity — the rela- 
 tion of their weight to their volume. The density of bodies is 
 estimated by certain standards ; that for solids being pure dis- 
 tilled or rain water (=1.000) at 60° F. The number, there- 
 fore, expressing the specific gravity of a body is the number 
 of times it is heavier or lighter than an equal volume of water. 
 For example, if two bodies of equal bulk differ in density 
 in the ratio of one to two, the latter is said to have twice the 
 specific gravity of the former, and so in proportion. There- 
 fore, " the volumes being equal, the densities of bodies are 
 directly as their weights; or, the weights being equal, the 
 densities are inversely as their volumes." 
 
 " Thus, if a cubic centimetre of iron weighs 7.8, while an 
 equal volume of water weighs only one gramme, 7.8 is the 
 specific gravity of iron." Hence, to find the density or spe- 
 cific gravity of a solid substance, its absolute weight must be 
 divided by the weight of an equal volume of water. 
 
 Specific Gravity of Solids. By means of the Hydro- 
 static Balance. — The two principal operations for estimating 
 the specific gravity of a solid heavier than water, are : First, to 
 weigh it accurately in air ; and secondly, to weigh it in water. 
 The weight at each weighing must be immediately noted in 
 the record book. 
 
 All of the finer balances are provided with a supplementary 
 pan (Fig. 62), for these weighings in fluids. Though neces- 
 sarily but one-third the depth df the regular pans, it is accu- 
 rately made so as to exactly counterbalance either of them, 
 and when adjusted to the beam, in its stead, to maintain per- 
 fect equilibrium. The hook beneath the pan is a convenience 
 for the suspension of the body to be weighed. This arrange- 
 ment permits the weighing of the body in air, and subse- 
 quently in water, without disturbing it or the balance. The 
 process is as follows : Suspend the body to be weighed by a 
 
SPECIFIC GRAVITY OF SOLIDS. 113 
 
 very fine platinum wire or unspun silken thread, to the hook 
 at the bottom of the supplementary pan, and adjust this dish 
 to that side of the beam from which the regular dish has been 
 removed to give place to it. There are other substitutes 
 for platinum and silk, but being more permeable and less 
 capable of furnishing a very fine and strong thread, they do 
 not afford such nice results in delicate experiments. This 
 done, take the weight of the body in air, observing the requi- 
 site precision in Weighing, and note it down in the record 
 book without delay. To take the weight in water, it is now 
 only necessary to convey a beaker glass containing that 
 liquid, immediately under the dish, and carefully to immerse 
 therein the suspended body. This vessel must be of diame- 
 ter sufficient to allow a free play of the body without contact 
 with its sides. Fig. 62, represents the whole arrangement. 
 In ii^troducing the body into water, particu- 
 larly if it presents rough surfaces, the air Fig. 62. 
 attaches itself in bubbles, which must be re- 
 moved with either a camel's hair pencil or 
 wooden stick. These precautions being duly 
 observed, put the balance in action and take 
 the weight of the body, and immediately re- 
 cord it. The apparent loss of weight repre- 
 sents the weight of the bulk of water which 
 the body displaces, and hence we have the 
 requisite data upon which to calculate its 
 specific gravity, viz., its weight in air and 
 the weight of its own bulk of water. 
 Thus, for example, the body weighs : — 
 
 In air . . . . 373 grains. 
 In water ... 341 " 
 
 Loss . . 32 " 
 
 By following the rule, and dividing the total weight by the 
 loss of weight in water, thus 373 -r- 32, we have 1.165 as its 
 specific gravity or density. 
 
 If the body is lighter than water, a weight of known mag- 
 nitude and density is joined with it to sink it. The weight 
 may be a capsule, and form a part of the furniture of the ba- 
 lance for this especial purpose. It should be cullendered to 
 allow the free escape of the globules of air adherent to the 
 
114 SPECIFIC GRAVITY: — HYDROSTATIC BALANCE. 
 
 body, after receiving which, it should be suspended to the 
 short pan as before directed. 
 
 In this, as in the previous instance, the weight required to 
 re-establish the equilibrium disturbed by the immersion of the 
 body in water, expresses the weight of the volume of water 
 displaced. 
 
 ''The rule, therefore, is — from the difference between the 
 weight of the two in water and their weight in air, subtract 
 the difference between the weight of the heavy solid in air and 
 its weight in water ; the remainder is the weight of a quantity 
 of water equal in bulk to the light solid, from which the spe- 
 cific gravity of the substance may be obtained by simple pro- 
 portion. 
 
 "As an example, suppose the following case: — 
 
 1. The weight of the light solid in air . .12 grs. 
 
 2. The weight of the heavy solid in air . 22 " 
 
 3. The weight of the heavy solid in water . 19 " 
 
 4. The weight of both tied together in water 8 " 
 
 "Then, from the weight of both in air (12 + 22) 34 grs. 
 Deduct the weight of both in water . . . 8 " 
 
 26 " 
 "And from the remainder deduct 22— 19= 3 3 " 
 
 "Which gives the weight of the bulk of 1 qo a 
 water displaced by the light body alone J 
 
 " The following proportion then affords the specific gravity 
 of the body: — 
 
 as 23 : 12 : : 1. : 0.5217." 
 
 [Parnell.) 
 
 If the substance is porous or in powder, its specific gravity 
 is better estimated by weighing it in the bottle (Fig. 64), after 
 the precaution of disengaging all adherent globules of air ; 
 otherwise it must, in following the preceding process, be 
 weighed in a capsule, counterpoised first in air and afterwards 
 in water. The water also should, before being used for this 
 purpose, be freed of any contained air by pouring it several 
 times from one vessel to another. 
 
 When the body is soluble in water, it must be replaced by 
 some other liquid of determined specific gravity, which is 
 without action. Olive oil, spirits of turpentine and alcohol, 
 are applicable, one or the other, for most cases. 
 
SPECIFIC gravity: — STOPPERED FLASK. 115 
 
 " The specific gravity of the substance is then found by 
 the following proportion, — As the density of water is to the 
 density of the liquid used, so is the density of the substance 
 in relation to the liquid in which it is weighed as unity, to 
 its density compared with water as unity." 
 
 " By the above described process, we find how much a cer- 
 tain quantity of fluid weighs which has the same volume with 
 the body to be weighed, and when once the specific gravity 
 of the fluid is known, it is necessary to ascertain the weight 
 of an equal volume of water." 
 
 '' Let it be assumed, that a piece of salt, which is insoluble 
 in oil of turpentine, weighs 0.352 gram., and displaces when 
 put into the glass 0.13 gram, of oil of turpentine. The spe- 
 cific gravity of this fluid is 0.8725; an equal volume of water 
 will therefore weigh — " 
 
 13 
 ' = 0.149, and the specific gravity of the salt is, there- 
 
 The preceding mode of taking the specific gravity of sub- 
 stances is founded upon the Archimedean law of hydrostatics, 
 " that the weight of a substance in any medium is less than 
 its absolute weight, by the weight of the bulk of the medium 
 which it displaces, obviously its own bulk." It is, however, 
 objectionable, as being liable to give inaccurate results, and, 
 therefore, we proceed to speak of a better method. 
 
 2d. By means of a Stoppered Flash. — In this mode of 
 weighing, which is very available for taking the density of 
 minute bulks of matter, and applies to bodies either heavier 
 or lighter than water, the same attention to temperature is 
 requisite, as in the preceding process. 
 
 The glass bottle in which the body is to be weighed, is of 
 form, as shown by Fig. 64. Its stopper should be round, 
 slightly conical, and accurately ground. To 
 facilitate the egress of any excess of water, Fig. 63. Fig. 64. 
 in case of expansion by heat, and to enable ^ 
 it to sink to a uniform depth in all posi- 
 tions, the centre of the stopple should be 
 perforated. The precision with which the 
 bottle and its stopper are manufactured, 
 has an important influence in bringing out 
 
116 SPECIFIC GRAVITY: — GRAVIMETER. 
 
 an exact result. This bottle is especially adapted for taking 
 the specific gravity of liquids, and its capacity may be from 
 100 to 1000 grains of distilled water. 
 
 Three weighings are required in taking the specific gravity 
 by this mode. The flask is first filled with water, so as to ex- 
 clude all air, then conveyed to the balance and accurately 
 counterpoised. The body to be examined is then placed in 
 the same pan with the flask, and the balance being again set 
 in action, the weight of the body is expressed by the addi- 
 tional weight necessary to produce equilibrium; and that of 
 the body and flask by the whole weight. The substance being 
 examined, is then placed in the flask, which is again weighed, 
 after having been wiped clean, to free it from the displaced 
 fluid which has flowed over its sides. The third weighing is 
 to determine the quantity of water, which is a volume equal 
 to its own bulk, displaced by the immersed body. Having 
 thus obtained the requisite data, we calculate as follows : 
 
 " The glass vessel with water weighs . . 13.52 grms. 
 The body 4.056 " 
 
 Both together 17.576 " 
 
 " If, after throwing the body into the bottle, putting the 
 stopper in, and weighing the whole together, we find it to be 
 17.316 grammes, the weight of the water forced out by the 
 body must be 17.576 — 17.316 == 0.26 gram.; consequently 
 
 the specific gravity of the body is ' = 15.6." 
 
 3d. By means of the Areometer. — The areometer is an 
 instrument which may be conveniently substituted for the 
 balance in taking the specific gravity of solids. That known 
 as Nicholson's is most generally used. Muller describes the 
 apparatus and the mode of manipulating with it, clearly and 
 concisely, as follows: 
 
 " To a hollow glass or metal body v, Fig. Q^, a small heavy 
 mass I (a glass or metal sphere filled with lead) is suspended, 
 and superiorly there is attached to it a fine stem supporting 
 a plate c, on which small bodies and weights may be laid. 
 The instrument floats vertically in the water, because its 
 centre of gravity is very low in consequence of the weight I. 
 The instrument is so arranged that the upper part of the body 
 
SPECIFIC GRAVITY OF FLUIDS. 
 
 117 
 
 Fig. 65. 
 
 V projects above the water. If now we lay the body whose spe- 
 cific gravity we would ascertain upon the plate 
 c, the instrument will descend, and by adding 
 additional weight, we may easily make it sink to 
 the point /, marked generally by a line on the 
 rod. We remove the mineral or other substance 
 we have been using, and substitute in its place 
 as many weights as will again make the instru- 
 ment sink to/. If, in the place of the mineral, 
 we have had to lay on n grains, the weight of 
 the mineral is equal to n grains. 
 
 "If, in this manner, we have ascertained the 
 absolute weight of the mineral, the n grains must 
 be again removed, and the body laid in a basket 
 placed between v and I. The instrument would 
 now again sink to / if the body laid in the basket ^ 
 had not lost weight by being immersed in the water : we must, 
 therefore, lay on the plate the weight m grains, that the body 
 may be immersed to the mark. In this manner we obtain 
 the absolute weight of the body n, and the weight of an 
 equal volume of water m ; the specific gravity we seek is, 
 
 therefore. 
 
 n 
 
 m 
 
 " If, for instance, we have to determine the specific gravity 
 of a diamond, we must lay it on the plate and add sufficient 
 weight to make the whole sink to /. If we find after remov- 
 ing the diamond, that we must lay on 1.2 grains to cause the 
 areometer to sink again to the same point, the absolute weight 
 of the stone would be 1.2 grains. These weights must be 
 again taken away and the diamond laid in the basket ; then, 
 in order to make the instrument sink to /, we must add 0.34 
 grains more ; the weight of a volume of water equal in volume 
 to the diamond is, therefore, 0.34 grains, and the specific 
 
 12 
 
 gravity required is — '-—■ = 3.53." 
 
 Specific Gravity of Fluids. — There are three modes of 
 determining the specific gravity of fluids, taking precedence 
 in the order in which we name them; by the stoppered flask, 
 the hydrometer and gravimeter. The first method yields the 
 greatest accuracy, and is that used in all nice investigations. 
 
 By the Flask. — Any small ground stoppered flask or vial 
 
118 SPECIFIC GRAVITY BOTTLES. 
 
 will answer for the purpose. It must first be brought to the 
 temperature of 60° F., then accurately weighed, and after 
 the removal of the stopper, filled with distilled water of corre- 
 sponding temperature. The stopper is then to be inserted, 
 and the water that it displaces wiped from the sides of the 
 vessel, which when dry is again carefully weighed. Its 
 increase of weight expresses that of the bulk of water which 
 it contains, and to save time and trouble, should be marked 
 with a diamond upon the neck of the flask to serve for future 
 experiments. 
 
 Glass flasks of this description are made by the manufac- 
 turers especially for this purpose. Their capacities are ar- 
 ranged so as to exactly receive a given quantity of distilled 
 water expressible by weight in round numbers. The sizes 
 vary from 100 to 1000 grs., but in each instance they have a 
 diamond scratch on their necks showing the measure of their 
 contained weight of water. They have been previously de- 
 scribed at p. 115, and are represented by Figs. 63, 64. The 
 smaller one is most used because of greater facility in han- 
 dling. Moreover the quantities of fluid under examination are 
 generally limited, and hence the convenience of a small flask 
 both on this account, and because it is more easily weighed in 
 a delicate balance. 
 
 For the more volatile liquids, the perforated stopple should 
 be replaced by a solid one, otherwise loss by evaporation may 
 occasion incorrect results. 
 
 If the chemist prefers purchasing a flask to graduating one 
 himself, it must be verified as above before being used, and if 
 the weight of its contents of water does not correspond with 
 the mark on the neck of the flask, or of the flask and water 
 combined with that of the weight generally accompanying it 
 as a convenient counterpoise, then the flask is not to be relied 
 on, and should either be corrected or rejected. 
 
 In either case the flask must be thoroughly cleansed, and 
 after each experiment should be repeatedly rins6d with dis- 
 tilled water, so that it may be perfectly clean and dry when 
 wanted for the next operation. In emergencies, the interior 
 may be dried by placing the flask upon the sand-bath ; in this 
 case, however, it will be necessary to allow its temperature 
 to fall again to 60° before using it. 
 
 Distilled water at 60° F. is the standard by which to esti- 
 mate the specific gravity of liquids. To take the density of 
 
SPECIFIC gravity: — HYDROMETER. 119 
 
 a liquid, equal bulks of it and water are taken at the balance. 
 The flask having been graduated, its weight and that of the 
 bulk of its contents of water are already known ; it is, there- 
 fore, only necessary to fill it with the liquid under examination 
 at 60° F., to the mark upon its neck, and after inserting the 
 stopper, carefully weigh it. Divide the weight thus found 
 by the weight of the water (as indicated on the flask) and you 
 obtain the specific gravity of the liquid. For example : — 
 The clean and dry flask weighs 400 grains, 
 
 do do filled with pure water, at 60° 900 " 
 
 Deduct the first from the latter and you obtain the weight of 
 the water = 500. Supposing, then, that the same bulk of 
 the liquid weighs 412 grains, then 412 -j- 500 = 0,824 its 
 specific gravity. 
 
 If the capacity of the flask is 1000 grains of water, and one 
 of that size. Fig. 63, may well be used, when the stock of the 
 liquid under examination is not limited, the process is still 
 easier. It is then only necessary to fill it with the fluid and 
 weigh it. The weight obtained expresses its specific gravity; 
 thus, taking mercury for example, a bulk of that metal equal 
 to the bulk of 1000 grains of water, is 13,500 grains, and, 
 therefore, these latter numbers express its density, taking care 
 to advance the decimal point three figures to the left, if the 
 water is taken as 1 instead of 1.000. 
 
 The vessel must, previous to weighing, be invariably wiped 
 dry exteriorly with a linen cloth, and to avoid any commu- 
 nication of heat from the hands, they should be gloved. 
 
 For determining the density of very minute quantities of 
 rare liquids, it will be necessary to have the aforementioned 
 bottles of miniature dimension, or else to replace them by glass 
 bulbs. 
 
 If the fluid is volatile and readily vaporizable, it should, in 
 being raised to the proper temperature, be heated over a 
 spirit lamp, in a test tube ; taking care to keep the finger over 
 its mouth, during the heating and cooling, so as to prevent 
 its being unclosed. 
 
 By the Hydrometer. — Hydrometers do not give very accu- 
 rate results, but they are convenient when time is an object, 
 and no great precision is requisite. Their action is based upon 
 the hydrostatic law, " that a floating body displaces its oivn 
 weight of the liquid in which it swims.'' 
 
120 
 
 SPECIFIC gravity: — HYDROMETERS. 
 
 The instrument consists of a glass stem A^ with an air 
 bulb, jB, beneath, properly ballasted with mercury or shot, D. 
 The depth to which the hydrometer will 
 Fig. 66. Fig. 67. gink in a liquid is proportional to its rarity, 
 for the denser the liquid, the less of it will 
 be displaced. A properly graduated scale 
 inserted within the stem or spindle, allows 
 the appreciation of the density of a liquid 
 by the greater or less depth to which it 
 sinks therein. The form of this instrument 
 is shown by Figs. ^^^ 67. They are con- 
 structed (Morjit's Applied Chemistry) with 
 different scales accordingly, as they are 
 intended for liquids rarer or denser than 
 water. The scales for those which are 
 rare run from zero (at the bottom of the 
 stem) upwards. The graduation of the scale 
 for liquids denser than water is reversed. 
 Areometers are variously graduated for diflferent liquids, 
 thus — 
 
 Those for ether mark upwards from 10 to 50° 
 
 " " spirits " " " 10 to 80 
 
 " " salts " downwards " to 40 
 " " acids " " " j:o 75 
 
 " " syrups " " " to 36 
 
 The following table shows the specific gravity numbers cor- 
 responding with Baume's areometric degrees : — 
 
 ^ 
 
HYDROMETERS — MANNER OP USING. 
 
 121 
 
 Liquids denser than water. 
 
 Less dense than water. 
 
 
 05 bo 
 
 i 
 1 
 
 
 1 
 
 
 i 
 
 ■p 
 
 t 
 
 Ofc bo 
 
 
 
 1.0000 
 
 26 
 
 1.2063 
 
 52 
 
 1.5200 
 
 10 
 
 1.0000 
 
 36 
 
 0.8488 
 
 1 
 
 1.0066 
 
 27 
 
 1.2160 
 
 53 
 
 1.5353 
 
 11 
 
 0.9932 
 
 37 
 
 0.8439 
 
 2 
 
 1.0133 
 
 28 
 
 1.2258 
 
 64 
 
 1.5510 
 
 12 
 
 0.9865 
 
 38 
 
 0.8391 
 
 3 
 
 1.0201 
 
 29 
 
 1.2358 
 
 55 
 
 1.5671 
 
 13 
 
 0.9799 
 
 39 
 
 0.8343 
 
 4 
 
 1.0270 
 
 30 
 
 1.2459 
 
 56 
 
 1.5833 
 
 14 
 
 0.9733 
 
 40 
 
 0.8295 
 
 5 
 
 1.0340 
 
 31 
 
 1.2562 
 
 57 
 
 1.6000 
 
 15 
 
 0.9669 
 
 41 
 
 0.8249 
 
 6 
 
 1.0411 
 
 32 
 
 1.2667 
 
 58 
 
 1.6170 
 
 16 
 
 0.9605 
 
 42 
 
 0.8202 
 
 7 
 
 1.0483 
 
 33 
 
 1.2773 
 
 59 
 
 1.6344 
 
 17 
 
 0.9542 
 
 43 
 
 0.8156 
 
 8 
 
 1.0556 
 
 34 
 
 1.2881 
 
 60 
 
 1.6522 
 
 18 
 
 0.9480 
 
 44 
 
 0.8111 
 
 9 
 
 1.0630 
 
 35 
 
 1.2992 
 
 61 
 
 1.6705 
 
 19 
 
 0.9420 
 
 45 
 
 0.8066 
 
 10 
 
 1.0704 
 
 36 
 
 1.3103 
 
 62 
 
 1.6889 
 
 20 
 
 0.9359 
 
 46 
 
 0.8022 
 
 11 
 
 1.0780 
 
 37 
 
 1.3217 
 
 63 
 
 1.7079 
 
 21 
 
 0.9300 
 
 47 
 
 0.7978 
 
 12 
 
 1.0857 
 
 38 
 
 1.3333 
 
 64 
 
 1.7273 
 
 22 
 
 0.9241 
 
 48 
 
 0.7935 
 
 13 
 
 1.0935 
 
 39 
 
 1.3451 
 
 65 
 
 1.7471 
 
 23 
 
 0.9183 
 
 49 
 
 0.7892 
 
 14 
 
 1.1014 
 
 40 
 
 1.3571 
 
 66 
 
 1.7674 
 
 24 
 
 0.9125 
 
 50 
 
 0.7840 
 
 15 
 
 1.1095 
 
 41 
 
 1.3694 
 
 67 
 
 1.7882 
 
 25 
 
 0.9068 
 
 51 
 
 0.7807 
 
 16 
 
 1.1176 
 
 42 
 
 1.3818 
 
 68 
 
 1.8095 
 
 26 
 
 0.9012 
 
 52 
 
 0.7766 
 
 17 
 
 1.1259 
 
 43 
 
 1.3945 
 
 69 
 
 1.8313 
 
 27 
 
 0.8957 
 
 53 
 
 0.7725 
 
 18 
 
 1.1343 
 
 44 
 
 1.4074 
 
 70 
 
 1.8537 
 
 28 
 
 0.8902 
 
 54 
 
 0.7684 
 
 19 
 
 1.1428 
 
 45 
 
 1.4206 
 
 71 
 
 1.8765 
 
 29 
 
 0.8848 
 
 55 
 
 0.7643 
 
 20 
 
 1.1515 
 
 46 
 
 1.4339 
 
 72 
 
 1.9000 
 
 30 
 
 0.8795 
 
 56 
 
 0.7604 
 
 21 
 
 1.1603 
 
 47 
 
 1.4476 
 
 73 
 
 1.9241 
 
 31 
 
 0.8742 
 
 57 
 
 0.7656 
 
 22 
 
 1.1692 
 
 48 
 
 1.4615 
 
 74 
 
 1.9487 
 
 32 
 
 0.8690 
 
 58 
 
 0.7526 
 
 23 
 
 1.1783 
 
 49 
 
 1.4758 
 
 75 
 
 1.9740 
 
 33 
 
 0.8639 
 
 59 
 
 0.7487 
 
 24 
 
 1.1875 
 
 50 
 
 1.4902 
 
 76 
 
 2.0000 
 
 34 
 
 0.8588 
 
 60 
 
 0.7449 
 
 25 
 
 1.1968 
 
 51 
 
 1.4951 
 
 
 
 35 
 
 0.8538 
 
 61 
 
 0.7411 
 
 The hydrometer is used with a tall glass jar (Fig. 
 68), which serves as a recipient for the liquid to be 
 tested. After having perfectly cleansed it of grease 
 and dirt with a cloth, it is to be placed in the jar and 
 the liquor, first brought to 60° F., added. When it 
 becomes stationary, note the degree at which it 
 stands. For verification, raise it an inch or more 
 out of the liquid and then let it gradually sink back 
 again. If it reaches the same point as before, the 
 first observation was correct. In reading the divi- 
 sions on the scale, do not take that line where the 
 liquid rises in wetting the stem of the instrument, 
 but note it at the real level, which is the curvature 
 9 
 
 Fig. 68. 
 
122 NICHOLSON'S GRAVIMETER. 
 
 produced by the ascending motion of the liquid against the 
 sides of the spindle. 
 
 The hydrometers graduated by Baume's process are gene- 
 rally used. Those made by F. A. Greiner & Co., Berlin, are 
 the most reliable. 
 
 For information, in detail, upon the construction of the 
 different kinds of hydrometers, see Encyclopoedia of Qhemistry^ 
 and M'Culloch's ''Investigations relative to Cane Sugar and 
 Report on Hydrometers.'' 
 
 By Nicholson's G-ravimeter. — " The specific gravity of 
 liquids may also be determined by Nicholson's areometer. 
 Fig. 65. As the instrument always sinks so far that its 
 weight, added to the weight upon the plate, is equal to the 
 mass of liquid displaced, we may, by the aid of this instru- 
 ment, ascertain ho^w much a definite volume of water weighs. 
 It is necessary, however, to know the weight of the instru- 
 ment itself. Suppose this weight to be n, we must lay on 
 some additional weight to make the instrument sink to/; if 
 we designate this addition by a, then is n •{■ a the weight of 
 water displaced. 
 
 "If we immerse the instrument in another liquid, we must 
 lay on another weight b in the place of 6f, to make the whole 
 sink to f; b will be greater than a if the liquid be denser, 
 and less than a if it be lighter than water. The weight of 
 the liquid displaced is n -\- b; but its volume is exactly as 
 great as the volume of the mass of water, whose weight is 
 7^ -h «, because the areometer has sunk equally deep in both 
 cases. 
 
 " Suppose the instrument weigh 70 grains, we must add 20 
 grains to make it sink in water, and 1.37, that it may sink 
 to the point/ in spirits of wine ; then the specific gravity of 
 
 spirits of wine is ^^ ' ^ = 0.793." 
 ^ 70+20 
 
 Specific Gravity of Gases. — The extreme lightness of 
 gases and vapors renders it inconvenient to compare their 
 weight with that of an equal bulk of water, and consequently 
 air is taken as the standard. 
 
 The mode of taking these specific gravities is thus con- 
 cisely and clearly described by Parnell, " From the careful 
 experiments of Br. Prout, it appears that 100 cubic inches 
 of atmospheric air deprived of carbonic acid and aqueous 
 vapor weighs 31.0117 grains, at 30 inches of the barometer, 
 
SPECIFIC GRAVITY OP GASES. 123 
 
 and at the temperature of 60° F. ; from which observation it 
 is easy to calculate the absolute weight of any bulk of a gas 
 from its specific gravity. Thus the specific gravity of chlo- 
 rine is found to be 2.47 ; to find how much 100 cubic inches 
 of that gas weigh at mean temperature and pressure, we 
 make use of the proportion, 
 
 asl. : 2.47 :: 31.01 : 76.59; 
 therefore 100 cubic inches of chlorine weigh 76.59 grains. 
 
 " The simplest method of obtaining the specific gravity of 
 a gas is the following: — The object is to ascertain the weight 
 of a bulk of gas equal to the bulk of a known weight of air. 
 For this purpose, a light glass globe, furnished with a stop- 
 cock, is very accurately weighed, when full of air; then ex- 
 hausted of its air, by connecting it with an air-pump, and 
 weighed in the vacuous state. The weighjt of the air with- 
 drawn by the exhaustion is thus ascertained. The globe, still 
 vacuous, is connected with a jar containing the gas which is 
 to be weighed, at the water or mercurial trough ; the jar hav- 
 ing a stop-cock at its top, into which the stop-cock of the 
 globe can be screwed air-tight. On gently opening both 
 stop-cocks, a quantity of gas rushes from the jar into the ex- 
 hausted globe, equal in bulk to the air withdrawn by the 
 exhaustion, if the surface of the liquid within the jar be 
 brought to the level of that without in the trough, and the 
 temperature of the air and the barometric pressure have not 
 varied during the experiment. The stop-cock being closed, 
 the globe is detached from the jar, and weighed. The dif- 
 ference between its weight when containing the gas, and when 
 vacuous, is the weight of a bulk of the gas equal to the bulk 
 of air whose place it occupies, the weight of which has already 
 been determined. 
 
 " Suppose the globe to lose 10.33 grains by exhaustion of 
 air, and, when exhausted, to gain 15.78 grains by admitting 
 carbonic acid gas; then, assuming 1. as the density of air, 
 we have the proportion, 
 
 as 10.33 : 15.78 : : 1. : 1.527; 
 the specific gravity of carbonic acid gas is, therefore, 1.527. 
 
 " Although thus simple in principle, the operation in its 
 details is one of extreme delicacy. From the facility with 
 which gases undergo a change in their bulk through variations 
 of temperature and pressure, it is obvious that if the tempera- 
 ture and barometric pressure vary during the course of the 
 
124 SPECIFIC GRAVITY OF GASES. 
 
 experiment, corrections must be made. As an illustration of 
 the necessary corrections, suppose the bulk of air to weigh 
 12 grains at the temperature of 60° F., and under a pressure 
 of 30 inches bar. ; and the same bulk of the gas whose density 
 is required to weigh 20 grains, but at the temperature of 50° 
 F., and under a pressure of 28 inches bar. The points to be 
 determined here are two : — 
 
 " 1. Considering the volume of the air withdrawn and the 
 gas admitted as 1., at the observed temperatures and pres- 
 sures, what would be the volume of the gas at the temperature 
 and pressure at which the air was weighed? 
 
 " And, 2, having obtained that volume, what is the cor- 
 responding increase or reduction in the weight of the gas? 
 
 " Performed according to rules which are given in the note 
 below,* the results of these calculations are as follows: — 
 
 " (a) A volume of gas equal to 1. at 50° F. is equal to 1.019 
 at 60° F. 
 
 " (5) A volume of gas equal to 1.019 at 28 inches of the 
 barometer is equal to 0.951 at thirty inches. 
 
 "A volume of the gas, therefore, equal to 0.951 weighs 20 
 grains ; a volume of air equal to 1. at the same temperature 
 and pressure weighing 12 grains. Then, if 0.951 vol. weighs 
 20 grains, 1 vol. should weigh 21.03 grains: and 
 
 as 12: 1:: 21.03: 1.75; 
 1.75 is, therefore, the density required. , 
 
 * " 1. For Changes in Bulk by Pressure. — The volume which a gas should 
 possess at one pressure may be calculated from its known volume at another 
 pressure, by the use of the following proportion : — As the pressure to which 
 the gas is to be corrected is to the observed pressure, so is the observed volume 
 to the volume required. In the example in the text (6), the pressure to which 
 the gas is to be reduced is 30 inches, the observed pressure 28 inches, and the 
 volume is 1.019. Then, as 30 : 28 : : 1.019 : 0.951. 
 
 " 2. For Changes in Bulk by Temperature. — From the very recent experiments 
 of M. Regnault, it appears that a volume of gas expands by heat ^^^ of its bulk 
 for each degree Fahrenheit. Hence, the volume of a gas at 0° F. being 1, at 
 any higher temperature it is found by the formula 1 -j — ^— -• The de- 
 termination of the volume of a gas at one temperature from its known volume 
 at another temperature maybe attained by the following formula: — Let f be 
 the temperature Fahrenheit at which the volume of the gas is observed ; t' the 
 temperature Fahrenheit to which the volume of the gas is to be reduced j x the 
 observed volume at t; and a/ the volume at t' required; 
 
 Then 0/ = ^-^^9 + -21^. 
 459 4- f 
 " 3. It is frequently necessary to combine corrections both for temperature 
 and pressure. In such a case, as in the example in the text, the reduction of 
 volume is first made for temperature, and that corrected volume is afterwards 
 reduced according to the pressure. 
 
SPECIFIC GRAVITY OF GASES. 125 
 
 " The state of dryness of a gas is another circumstance 
 which interferes with its volume ; for which reason, due care 
 should be taken to insure either the perfect dryness of the 
 gas, or its complete saturation with moisture. In the latter 
 case, the temperature must be noticed, and the observed 
 volume reduced according to the proportion of aqueous vapor 
 capable of existing in the gas at the observed temperature. 
 The proportions of vapor by volume contained in 1 vol. of the 
 saturated gas for temperatures between 40° and 80° F. are 
 expressed in the table at page 110. A cubic inch of aqueous 
 vapor corrected to the temperature of 60°, and at a pressure 
 of 30 inches, weighs 0.1929 grains. 
 
 " The preceding method of obtaining the density of a gas 
 still requires a slight correction from another circumstance, 
 when the temperature and pressure differ considerably at the 
 time of weighing the air and at the time of weighing the gas ; 
 but one so trifling that it may, in general, be neglected. 
 The necessity of this correction arises from the impossibility 
 of obtaining a perfect vacuum in the globe ; and the remain- 
 ing small quantity of air may occupy a different space when 
 weighed with the gas, to that which it occupied when the 
 globe was weighed with air ; and consequently, the bulk of 
 the gas admitted into the globe is not the same as the bulk of 
 the air withdrawn. If the amount of rarefaction of the air 
 in the exhausted flask is observed, by means of a barometer 
 gauge attached to the air-pump, the amount of the remaining 
 air may be calculated when the weight of the quantity with- 
 drawn is ascertained ; then the alteration to which it would 
 be subject in bulk by changes of temperature and pressure 
 may also be estimated, and a due allowance made on the bulk 
 of the gas admitted into the globe." 
 
 When the gas is corrosive in its action, as in the case of 
 chlorine, the balloon with its metallic cock must be replaced 
 by a glass flask with a nicely fitting ground stopper. This 
 flask is to be adjusted to a drying tube connected with the 
 vessel in which the chlorine is generated. The bent end of 
 the drying tube entering the flask should reach to its bottom. 
 The disengaged gas in passing through the tube parts with 
 its moisture, and reaching the flask descends to the bottom, 
 and displaces the air, which is expelled through the interstices 
 at the mouth around the tube. When the chlorine itself be- 
 gins to escape, it is evidence that all the air has been dis- 
 
126 
 
 SPECIFIC GRAVITY OF VAPORS. 
 
 placed, and the flask is then to be- slowly and gently detached 
 from the apparatus and hermetically closed with its ground 
 stopper. 
 
 Specific Gravity of Vapors. — There are two modes of de- 
 termining the specific gravity of vapors, the one devised by 
 Gay Lussac (Pelouze and Fremy's Qhimie Gfenerale^ vol. ii., 
 Traite de Manipulations Ohimiques, par A. Bobiere, vol. ii. 
 p. 467), and the other the preferable one of Dumas. It is as 
 follows : 
 
 Take a glass globe of about 12 to 16 oz. capacity, with a 
 long slender neck, wash it with distilled water, and carefully 
 dry it, either by slight warmth or by means of the exhausting 
 syringe and chlorcalcium tube, Fig. 69. After the balloon is 
 
 Fig. 69. 
 
 ^^mwxE 
 
 ^'^^ 
 
 ^ 
 
 perfectly dry, its neck is to be drawn out to a narrow tube 6 
 or 8 inches long, and bent nearly at a right angle, as shown 
 at a, Fig. 70. The tip is then to be removed with a file, and 
 the mouth of the tube rounded (not closed) over the blow-pipe 
 flame. The globe full of air is now weighed, with great pre- 
 cision, and afterwards warmed to expel a portion of its air. 
 This done, its beak is immediately dipped into the liquid or 
 melted* solid matter, and as the air within contracts by the 
 cooling of the bulb, which may be hastened by dropping ether 
 on its exterior, the fluid is drawn up. When the requisite 
 
 * If the solid body is not fusible, a given weight of it is introduced into the 
 globe, previously dried. The neck is then drawn out, the end removed and 
 placed in the balance. By deducting its weight from that of the whole balloon, 
 you obtain the weight of the balloon full of air. 
 
SPECIFIC GRAVITY OP VAPORS. 
 
 127 
 
 quantity, say 100 to 150 grains, has entered, the globe is at 
 once enclosed in a wire basket 6, Fig. 70, and introduced into 
 
 Fig. 70. 
 
 a water, saline, metallic or other bath, the temperature of 
 which exceeds the boiling point of the liquid, 50° or 60°. The 
 wooden support e, to an arm of which is suspended the ther- 
 mometer c, keeps the globe firmly fixed in the bath. 
 
 The bath is brought to ebullition, and as soon as it rises 
 above the boiling point of the substance, a jet of vapor escapes 
 through the tube, and as soon as it ceases, the point is sealed 
 up over the blow-pipe flame, observing at the same time the 
 temperature of the bath and the barometric pressure. 
 
 The globe thus closed is then withdrawn from the bath, 
 washed, dried, and again weighed. 
 
 To determine the capacity of the balloon, its tube is dipped 
 into mercury, and its point broken under the surface of the 
 metal, which immediately rushes in and fills the vacuum caused 
 by the condensation of the vapor, and should occupy the whole 
 interior. It is evident that the volume of mercury represents 
 the volume of the vapor at the noted temperature, and this 
 volume is determined by transferring the mercury to a gradu- 
 ated tube, and marking the number of cubic inches or centi- 
 metres which it occupies. 
 
 We thus have all the data necessary for calculating the 
 specific gravity of the vapor, having determined, experi- 
 mentally, — 
 
128 MEASURES AND MEASURING. 
 
 "1. The weight of the globe and air at ordinary tempera- 
 ture and pressure; 
 "2. The weight of the globe and vapor filling it at the 
 temperature of the bath, ^nd under ordinary pres- 
 sure; and, 
 " 3. The capacity of the globe. 
 " Having these results, we obtain by calculation, — 
 
 "1. The weight of the empty globe (by knowing the capa- 
 city of the globe, the weight of the air filling it can 
 be calculated, which, deducted from the weight of 
 the globe and air, leaves the weight of the globe 
 when vacuous); 
 . "2. The weight of vapor filling the globe at the tempera- 
 ture of the bath (by deducting the weight of the empty 
 globe from the weight of the globe and vapor) ; and, 
 " 3. The weight of air filling the globe at the temperature 
 of the bath, and at the pressure at which the globe 
 was sealed with the vapor. 
 " The last calculation is made according to rules given in 
 the note, page 124; having performed which, the density of 
 the vapor required is obtained by the simple proportion, — As 
 the weight of air filling the globe at the temperature of the 
 bath is to the weight of vapor filling the globe at the same 
 temperature, so is 1 to the density required." 
 
 CHAPTER IX. 
 
 MEASURES AND MEASURING. 
 
 Measuring of Fluids. — When great accuracy is required 
 in the estimation of fluids, their weight is determined; but in 
 ordinary operations, the amount of their volumes is obtained 
 by the employment of vessels purposely prepared and gradu- 
 ated with care and precision. 
 
 These vessels or graduates as they are called, are gene- 
 rally of two forms, those for the larger operations being 
 cylindrical, as shown by Fig. 71. This shape combines both 
 strength and convenience. For the smaller (ounce or drachm) 
 
MBASURINa OF FLUIDS. 
 
 129 
 
 graduates, the conical form, Fig. 72, is preferable, as giving 
 greater facility by its smaller surfaces, for accurately esti- 
 mating minute volumes. 
 
 Fig. 71. Fig. 72. Fig. 73. Fig. 74. 
 
 G-raduation, — For the large measures, the imperial pint is 
 the usual integer. To graduate a vessel to this extent, take 
 a glass balloon. Fig. 73, counterbalance it and weigh therein 
 accurately one pint imperial (8750 grs.) of distilled water, at 
 the temperature of 62° F., and at 30 inches of barometric 
 pressure. After the vessel has remained undisturbed upon a 
 level shelf, suflficiently long for its contents to acquire a smooth 
 steady surface, scratch upon the neck the exact level to which 
 the liquid rises. The narrower the neck of the flask the 
 greater the facility in noting this point without liability of 
 error. This weighed quantity of water is then to be trans- 
 ferred to the proof glass, under process, either of such a form 
 as shown in Fig. 71, or in Fig. 74, the latter, however, being 
 shorter and wider, is preferable for large sized graduates. 
 After the water has settled, and presents a smooth calm sur- 
 face, scratch its level accurately upon the exterior of the glass, 
 either with a diamond point or a sharp file. Thus you obtain 
 a pint measure, to graduate which into its subdivisions of 
 ounces and drachms, it is only necessary to take the pro rata 
 weights of the fractions of the pint, and proceed in manner 
 as above directed. So likewise, the vessel can be graduated 
 to pint divisions, in number as many as its capacity will ad- 
 mit, by multiplying the weights of water, and adding them to 
 those previously measured, noting the level of each with the 
 diamond. 
 
 The imperial pint is larger than the wine pint of 16 fluid- 
 
130 GRADUATION OP VESSELS. 
 
 ounces, in the ratio of 6 to 5, and, therefore, its subdivisions 
 must number 20. This makes a discrepancy, the inconve- 
 nience of which can be remedied by having a second scale 
 upon the same glass, showing their relative values. The only 
 disadvantage is the trouble of a second graduation, which is, 
 however, compensated for in the convenience of the first scale, 
 each division of which, unlike the fluidounce of the wine pint, 
 represents a fluidounce exactly, weighing one ounce avoir- 
 dupois of distilled water. 
 
 The plan of graduating the pint, itself estimated as above, 
 into its subdivisions by apportioning its height into the requi- 
 site number of equal parts, by means of a rule, will only 
 answer for vessels of uniform diameter throughout, and which 
 are only intended for the grosser operations of measuring. 
 
 Those graduates, which are intended for nice purposes, 
 should also have a third scale graduated in cubic inches. 
 The cubic inch equals 252.458 grains of distilled water, at 
 temperature and pressure the same as above. As there is 
 sufficient room upon the glass for all of these scales without 
 the necessity of crowding them together — there should be an 
 equal interval between them. 
 
 To graduate a vessel to the litre of the French standard, 
 substitute 1 kilogramme for the 8750 grains distilled water, 
 and proceed as above, making the subdivisions pro rata. 
 
 The graduates and cubic inch bottles are less to be relied 
 on when purchased than when carefully graduated by the 
 operator himself, and they should never be used in important 
 experiments without having been previously verified. 
 
 For the graduation of the ounce and drachm measures, and, 
 indeed, all vessels of small diameters and capacities such as 
 tubes and the like, the divisions of which must necessarily for 
 want of space closely approximate to each other, mercury is 
 much preferable to water. Mercury gives a more level and 
 distinct surface than water, and not being attracted by the 
 sides of the vessel, allows a greater accuracy in making the 
 subdivisions, especially in very narrow tubes. The addition 
 of one grain of lead to every 4000 grains of quicksilver im- 
 proves the mercury for this purpose, but it must be otherwise 
 pure and free from dross and film. A cubic inch of pure 
 mercury, according to Faraday, weighs 3425.35 grains, at 
 62° F. 
 
 There should be a series of these graduated glasses, ranging 
 from a double pint down to a drachm. 
 
GKADUATION OP TUBES. 131 
 
 For the tubes and other vessels used in analytic research, 
 the decimal divisions are both convenient and necessary. If 
 a cubic inch is to be divided into tenths and hundredths, the 
 former are graduated by the space occupied in the tube by 
 the one-tenths (342.50 grs.) of a cubical inch of mercury, and 
 each tenth division coincident with the level of the metal 
 within, is marked upon the scale. So also, in like manner, are 
 the hundredths graduated by substituting 34.25 grs. (the hun- 
 dredth of a cubic inch at 62°) for the 342.50 grs. mercury. 
 
 To give a clear idea of the mode of preparing a measure 
 with mercury, let us suppose that a tube is to be graduated 
 to cubic centimetres (of the French standard). In the first 
 place a narrow strip of white paper, with a line ruled down its 
 centre, is to be pasted lengthwise upon the side of the glass 
 to be graduated, the length of the paper of course corre- 
 sponding with the height of the glass. 13.59 grammes of 
 mercury are next to be accurately weighed out, and this 
 quantity, which represents a cubic centimetre, is to be poured 
 into the tube, held vertically by a support similar to A, in 
 Fig. 79. After the vessel has stood long enough for the 
 liquid to become quiet and assume a smooth surface, its level 
 is noted down, and its corresponding height marked with ink 
 upon the paper slip. The space which this bulk of quick- 
 silver occupies in the tube equals a cubic centimetre, and 
 when accurately noted, may serve as a standard for the gradu- 
 ation of vessels of larger capacity ; for these cubic centimetral 
 divisions can be multiplied, merely by multiplying this given 
 bulk of mercury, and noting and marking upon the paper, the 
 level of each addition as its surface becomes smooth. Ten 
 times the above weight of mercury gives a decimetral division, 
 and one-tenth of it a millimetral division, and thus we have 
 an easy mode of enlarging or diminishing the subdivisions of 
 the scale. 
 
 By having the tubes accurately graduated so that their 
 divisions exactly correspond with the weights of the balance, 
 we acquire the convenience of calculating at once the weight 
 of gases from their measured volume. 
 
 The plan of consecutive weighings, involves a good deal of 
 trouble and labor where large vessels are being prepared, and 
 hence, in such cases, the convenience of this mode of multi- 
 plying the divisions by an accurately adjusted measure. 
 
 In marking the scale, let those lines designating the tenths 
 
132 
 
 GRADUATED VESSELS. 
 
 Fig. 75. 
 
 extend in width a little beyond those denoting the twentieths, 
 and these latter, in their turn, a little beyond those expressing 
 the hundredths. Fig. 75 represents a gradu- 
 ated glass with a properly written scale, upon 
 which the tenths are shown by figures. 
 
 As these glasses are to be standard graduates 
 for a variety of purposes in the laboratory, the 
 scale should be indelible, or etched upon the 
 glass. For this purpose the paper scale must 
 be covered with a thin transparent film of 
 melted white wax. When the wax has cooled 
 and hardened, the lines and figures are graved 
 out of the paper with a sharp pointed style or 
 buren, and the exposed surfaces of the glass 
 subjected to the action of fluohydric acid, as 
 directed at p. 68. This done, and the wax 
 scraped ofi", the etched portions show out dis- 
 tinctly, and are better defined than if they had 
 been scratched, as is sometimes done, with the 
 diamond point or file. 
 
 Be careful that the subdivisions conform accurately among 
 themselves, and in the aggregate precisely with their integer. 
 The volumes as expressed by the lines on the scale should 
 also exactly agree with their corresponding weights, for upon 
 these conditions depends the accuracy of results. 
 
 Tubes for eudiometry. Fig. 76, and proof glasses for alka- 
 limetry. Fig. 77, and all other vessels used in 
 Fig. 76. Fig. 77. chemical operations for measuring, are gradu- 
 ated in like manner. The bell glasses, (Fig. 
 61,) for which and all large vessels, water is 
 preferable, should be graduated into double 
 cubic centimetres, so that every divisional line 
 may correspond to two centimetres ; and the 
 tubes into double cubic millimetres, so that 
 every line may correspond to two cubic milli- 
 metres. 
 
 Dr. Henry proposes, as a quick and accurate 
 method of graduating tubes for eudiometry, 
 &c., to have a standard tube, 0.08 of an inch 
 in diameter, and carefully divided into 10 equal 
 parts, of 10 grains of mercury (60° F.) capacity each. 
 
 The vessels should be of clear glass. The tubes must be 
 
 (^ 
 
MEASUREMENT OF GASES. 
 
 133 
 
 thiek, and strong enough to support the weight of their full 
 contents of mercury. For the convenience of closing their 
 mouths with glass disks, their ends may be ground flat and 
 even. 
 
 In all operations of graduation, the waste of mercury is 
 avoided by working over a porcelain plate, or, what is better, 
 the mercury trough, Fig. 79. The metal may be conveyed 
 to the vessels in the pipette. Fig. 59, which enables the addi- 
 tion or removal of minute portions, as the case may require. 
 
 The requirements of the laboratory call for an assorted 
 stock of graduated tubes and proof glasses, varying in diameter 
 from a quarter to two inches. 
 
 Below is a useful table, showing the value of the measures 
 of capacity in cubic inches, grains, and as compared with 
 apothecaries' measure. 
 
 
 
 Grains of dis- 
 
 Apothecaries' 
 
 
 Cubic inches. 
 
 tilled water. 
 
 measure. 
 
 Imperial gallon 
 
 277.274 
 
 70000 
 
 9.966+ 
 
 Imperial pint 
 
 34.65925 
 
 8750 
 
 
 Imperial fluidounce 
 
 1.7329625 
 
 437.5 
 
 
 The old wine pint . 
 
 28.8827 
 
 7291.666 
 
 16 fl. oz. 
 
 Old fluidounce 
 
 1.805169 
 
 455.73 
 
 8 drachms. 
 
 Cubic inch 
 
 1. 
 
 252.458 
 
 
 Litre 
 
 61.02525 
 
 15406.312 
 
 2.1135 pints. 
 
 Decilitre . 
 
 6.10252 
 
 1540.631 
 
 3.3816 fl. oz. 
 
 Centilitre . 
 
 0.61025 
 
 154.063 
 
 2.7053 fl, draohras. 
 
 Millilitre . 
 
 0.06102 
 
 15.406 
 
 16.2318 minims. 
 
 Measurement of Cfases. — In measuring, a required volume of 
 any gas, a graduated tube, like the one shown in Fig. 78, is first 
 filled with mercury or water as the case may be, in the pneu- 
 matic trough, and placed upon the shelf. When the tube is too 
 slender to sustain itself in an upright position, it is then con- 
 venient to use the clamp and support, A Fig. 79. If the mouth of 
 the receptacle of the gas is wide, it is necessary, before trans- 
 ferring to the graduating tube, to place a small funnel in its 
 submerged end, so that the ascending bubbles may be received 
 upon a larger surface. By giving the reservoir, generally a 
 bell glass, a slightly inclined position, so that the edge of its 
 mouth may reach under the funnel, the transfer is made easily 
 and without loss. As soon as the requisite quantity has been 
 transferred, the connection must be broken, and both the bell 
 and tube made to resume their former positions on the shelf. 
 (See Transfer of G-ases.) The tube is then to be depressed 
 in the trough until the metal, inside and outside, is at the 
 
134 
 
 Fig. 78. 
 
 MEASUKEMENT OF GASES. 
 Fig. 79. 
 
 same level. This mode subjects the gas only to atmospheric 
 pressure, but the tube must be held by a cork-lined clamp, as 
 in Fig. 79, or linen holder, and not in the naked hand, the 
 warmth of which, by expanding the gas, would be a source of 
 error. 
 
 It is very difficult to transfer a quantity of gas exactly cor- 
 responding with a division of the tube at one trial — several 
 attempts are requisite, except in cases of consummate mani- 
 pulation. It is perhaps better to transfer the last portions 
 from a small tube. The gas passing through very slowly and 
 in fine bubbles can by this arrangement be stopped off as 
 soon as the volume which has entered accords with the divi- 
 sion indicated. When more than sufficient has been trans- 
 ferred, place the first finger upon the mouth of the tube so as 
 to leave a partial opening, and incline it sufficiently to allow 
 the exit of the redundant gas. Examine anew the contained 
 volume, and if it is still in excess, repeat this operation until 
 the level of the liquid reaches the proper height. 
 
 To insure accuracy in the comparison of volumes of differ- 
 ent gases, they must necessarily be measured at the same 
 temperature and under the same pressure. The proof glasses 
 in which they are estimated should be kept out of the influence 
 of unequal warmth during the process, for the action of heat 
 upon the volume of gases is a cause of considerable error. 
 
 In order to determine with precision, the exact height 
 which the water or mercury assumes, the vessel should be 
 placed at repose upon a level shelf, and the eye directed on a 
 line with the surface of the fluids, and the height read off 
 
MEASUREMENT OF GASES. 1S5 
 
 accordingly. This notation requires some care and precision, 
 for as mercury assumes a convex surface, owing to its own 
 cohesion, and water a concave one, because of the attraction 
 for the walls of the tube, especially in narrow cylinders, the 
 curve thus occasioned presents an impediment to the ready 
 determination of the exact level. 
 
 When water is the confining fluid, read the real surface 
 in the middle of the dark zone formed by the water around 
 the inner walls of the tube ; on the other hand, when mercury 
 is used, " place the real surface in a line drawn exactly in the 
 centre between the highest point of the surface of the mer- 
 cury and the points at which the latter is in actual contact 
 with the walls of the tube." 
 
 In either case the temperature of the fluid and gas should 
 be uniform. When the bulk of the containing fluid is sufficient 
 to allow the entire immersion of the cylinder, this is easily 
 eflFected ; otherwise, it becomes necessary to equalize the tem- 
 perature of the surrounding air, by keeping the cylinder ex- 
 posed to both, in order to determine accurately the degree 
 of the scale at which the mercury or water stands. 
 
 Another important matter, as before mentioned, in the 
 comparison of volumes of different gases, is the necessity of 
 uniform pressure, in their measurement. If the level of the 
 containing fluid within and without the cylinder exactly cor- 
 responds, the pressure upon it is directly shown by the baro- 
 meter. A higher level, internally, indicates less pressure, 
 and vice versa : when the fluid stands higher outside of the 
 cylinder than within it, the level may be restored by raising 
 the tube ; in the opposite case by depressing the tube. These 
 operations of adjusting the level are more difficult when 
 mercury is the containing fluid. In operations occupying 
 much time, the barometer should be frequently consulted, 
 so as to guard against any alteration sufficient to impair the 
 results. 
 
 Fig. 80. 
 
186 MEASUREMENT OF TEMPERATURE. 
 
 Ker's tube, constructed for the measurement of gas at the 
 time of its disengagement, is shown by Fig. 80. The branch 
 a, ten inches in length, glass stoppered and graduated to two 
 cubic inches, is the recipient of the gas disengaged from the 
 material in the bulb c, by the action of a reagent introduced 
 in the other branch b. The gas collecting in a is there mea- 
 sured by the scale, previous to being transferred for exami- 
 nation. 
 
 CHAPTER X. 
 
 MEASUREMENT OF TEMPERATURE. 
 
 Temperature is estimated by means of two instruments, 
 the pyrometer and thermometer, the action of which is based 
 upon the relative expansibility of bodies under the influence 
 of heat and cold. They do not therefore indicate the amount 
 of heat contained in a body, but only the comparative tem- 
 perature of two or more bodies. 
 
 The Pyrometer. — This instrument is rarely used in the 
 ordinary operations of the laboratory, it being only applicable 
 to the measurement of heats more intense than can be borne 
 by thermometers. Pyrometers are constructed of solid sub- 
 stances, though gaseous bodies, on account of their sensitive- 
 ness to heat or cold and greater uniformity of expansion, would 
 be preferable. Daniell's instrument is the most approved, 
 and by skilful management may be made to give accurate 
 indications. Its principal application is in furnace operations. 
 In assaying, where the required temperature varies with the 
 metal under process, it is particularly available in determining 
 the heat of the furnace ; for much of the accuracy of the assay 
 depends upon the temperature at which it is made. Fig. 81 
 represents the apparatus. 
 
 " It consists of two parts, which may be distinguished as 
 the register 1, and the scale 2. The register, a, is a solid 
 bar of black-lead earthenware highly baked. In this a hole, 
 a a, is drilled, into which a bar of any metal, six inches long, 
 may be dropped, and which will then rest upon its solid end. 
 
THE PYROMETER. 
 
 137 
 
 A cylindrical piece of porcelain c, called the index, is then 
 placed upon the top of the bar, and confined in its place by a 
 ring or strap of platinum d, passing round the top of the 
 
 Fig. 81. 
 
 register, which is partly cut away at the top, and tightened 
 by a wedge of porcelain e. When such an arrangement is 
 exposed to a high temperature, it is obvious that the expan- 
 sion of the metallic bar will force the index forward to the 
 amount of the excess of its expansion over that of the black- 
 lead, and that when again cooled it will be left at the point 
 of greatest elongation. What is now required, is the mea- 
 surement of the distance which the index has been thrust 
 forward from its first position, and this, though in any case 
 but small, may be effected with great precision by means of 
 the scale." 
 
 " This is independent of the register, and consists of two rules 
 of brass,// and g, accurately joined together at a right angle 
 by their edges, and fitting square upon two sides of the black- 
 lead bar. At one end of this double rule, a small plate of 
 brass h, projects at a right angle, which may be brought down 
 upon the shoulder of the register formed by the notch cut 
 away for the reception of the index. A movable arm D, is 
 attached to this frame, turning at its fixed extremity on a 
 centre 2, and at its other carrying the arc of a circle, whose 
 radius is exactly five inches, accurately divided into degrees, 
 and thirds of a degree. Upon this arm, at the centre of the 
 circle k, another lighter arm c is made to turn, one end of 
 which carries a nonius H with it, which moves upon the face 
 10 
 
138 
 
 MEASUREMENT OP TEMPERATURE. 
 
 of the arc, and subdivides the former graduation into minutes 
 of a degree ; the other end crosses the centre and terminates 
 in an obtuse steel point w, turned inwards at a right angle. 
 
 " When an observation is to be made, a bar of platinum or 
 malleable iron is placed in the cavity of the register ; the 
 index is to be pressed down upon it, and firmly fixed in its 
 place by the platinum strap and porcelain wedge. The scale 
 is then to be applied by carefully adjusting the brass rule to 
 the sides of the register, and fixing it by pressing the cross 
 piece upon the shoulder, and placing the movable arm so 
 that the steel part of the radius may drop into a small cavity 
 made for its reception, and coinciding with the axis of the 
 metallic bar. The minute of the degree must then be noted 
 which the nonius indicates upon the arc. A similar obser- 
 vation must be made after the register has been exposed to 
 the increased temperature which it is designed to measure, 
 and again cooled, and it will be found that the nonius has 
 been moved forward a certain number of degrees or minutes. 
 The scale of this pyrometer is readily connected with that of 
 the thermometer by immersing the register in boiling mer- 
 cury, whose temperature is as constant as that of boiling 
 water, and has been accurately determined by the thermo- 
 meter. The amount of expansion for a known number of 
 degrees is thus determined, and the value of all other expan- 
 sions may be considered as proportionate." 
 
 " The following is a list of the melting points of some of 
 the metals, and it is obvious that in an assay of each particular 
 metal, the temperature employed must exceed by a consider- 
 
 able number of degrees its melting point, 
 fore, very useful. 
 
 Tin melts at 
 
 Bismuth 
 
 Lead 
 
 Zinc 
 
 Cadmium 
 
 Silver 
 
 Copper 
 
 Gold 
 
 Cast iron 
 
 Cobalt and nickel rather less fus 
 
 The table is, there- 
 Fahrenheit. 
 422° 
 497 
 612 
 773 
 442 
 1860 
 1996 
 2016 
 2786^^ 
 ble than iron." 
 
 Baniell, 
 
THERMOMETERS. 
 
 139 
 
 Thermometers. — A thermometer consists of a graduated 
 cylindrical stem, with a uniform capillary bore, 
 having one of its ends blown into a bulb and filled Fig. 82. 
 with mercury or alcohol, and the other hermeti- ^ 
 
 cally closed, the space above the column of fluid 
 being a vacuum, or as nearly as possible devoid of 
 air. 
 
 Mercury, on account of its greater equability of 
 expansion, and of its boiling point being as high as 
 650° F., is more available in the construction of 
 thermometers for measuring temperatures exceeding 
 that of boiling water (212° F.). Alcohol, on the 
 other hand, by reason of its eminent property of 
 dilatation is more applicable for determining tem- 
 peratures lower than the freezing point of mercury, 
 its point of congelation being as far down as — 90° F. 
 
 The two points of graduation^ are the freezing I 
 
 and boiling points of water, the interval between 
 each being diflferently apportioned, according as 
 the scale of Fahrenheit, Celsius, or Reaumur (the three most 
 in use) is employed. 
 
 Fahrenheit's 
 Scale. 
 
 Fig. 83. 
 
 Centigrade 
 Scale. 
 
 Reaumur's 
 
 Scale. 
 
140 MEASUREMENT OP TEMPERATURE. 
 
 Fahrenheit's scale ranges from 32° to 212°; that of Celsius 
 (centigrade) from 0° to 100° ; Reaumur's from 0° to 80°. The 
 first is most popular in England and in this country ; the 
 second in France, and the third in Russia, Spain, and part of 
 Germany. The scale of Fahrenheit has its zero at 32° below 
 the freezing point of water, and the other two exactly at that 
 point. Therefore, in comparing the degrees of the former 
 with those of the latter, the negative or those below zero have 
 a prefix of the minus ( — ) sign, and the positive or those 
 above, the plus (4-) sign. The diagram (Fig. 83) will present 
 the relative position of the corresponding degrees of the three 
 scales. 
 
 The following rules will be found convenient for translating 
 the degrees of one scale into those of another : 
 
 1. To reduce Centigrade degrees to those of Fahrenheit, 
 multiply by 9, and divide by 5, and to the quotient add 32, 
 that is, — 
 
 ^5B^liL?+32 = Fahr. 
 5 
 
 2. To reduce Fahrenheit's degrees to Centigrade : — 
 
 Fahr.-32x5 ^Cent. 
 
 3. To reduce Reaumur's to Fahrenheit's : — 
 
 Reau. X 9 
 
 -f 32 = Fahr. 
 Reaum 
 = Reaumur. 
 
 4 
 4. To convert Fahrenheit's to Reaumur's : — 
 Fahr. — 32 x 4 
 
 9 
 
 A slender stem and precise uniformity of bore are indis- 
 pensable to the accuracy of a thermometer. The tube must 
 also be entirely void of air, as is known upon its inversion 
 when the contained mercury makes a free and rapid descent. 
 Moreover, the graduation of the scale must be verified, and to 
 do this, the bulb is immersed in a mixture of salt and snow 
 to test the accuracy of its freezing degree, and afterwards in 
 boiling water (under the ordinary pressure of the atmosphere) 
 to observe its boiling point. If in either case when the fluid 
 becomes stationary, after sufficient delay for the bulb to ac- 
 quire the temperature of the bath, it corresponds with the 
 degree marked upon the scale, its graduation as regards the 
 freezing and boiling points is correct. To determine the 
 
THERMOMETERS. 141 
 
 exactness of the intermediate space, the length of the interval 
 is measured with a pair of compasses, and it is then easy to 
 ascertain by means of an accurate ruler, if the divisions accord 
 with each other, and in the aggregate with the total length 
 of the scale. 
 
 For measuring temperatures higher than 580° F., the top 
 of the thermometer should be unsealed and the mercury ex- 
 posed to the pressure of the atmosphere, for if hermetically 
 closed, it will boil at that point and burst the tube. 
 
 The tube, as before said, should be as slender as possible, 
 and not too long, otherwise in testing shallow solutions in 
 ebullition, that part of the stem which is above the liquor is 
 exposed to the heat of the rising vapor, and as the expansion 
 to mercury within would be thus estimated with that of the 
 contents of the bulb, the only part heated at the time of 
 graduation, incorrect conclusions would be drawn. 
 
 In ascertaining the condition of a liquid with regard to heat 
 or cold, the thermometer is gradually introduced into it, 
 moved around several times so as to produce an equable dif- 
 fusion of temperature, and after the mercury has become 
 stationary at a certain point, the degree coincident with that 
 point is noted down as the temperature. 
 
 The scales of thermometers are most generally gra- -p- g^^ 
 duated upon a wooden slip or support, to which the 
 stem is secured by clamps and screws. In this case, ^ 
 the scale is hinged (Fig. 82) so as to afford convenience 
 in the use of the thermometer for taking the boiling 
 point of solutions without injury to the scale. 
 
 Some manufacturers make the thermometers wholly 
 of glass, and etch the scale upon the broad sides of 
 the flat tube, as shown by Fig. 84. This kind is very 
 convenient for passing through tubulures, but is well 
 replaced by those with the scale written upon paper 
 and enclosed with the thermometer stem in a glass 
 tube. These latter are made in the most skilful man- 
 ner by Greiner & Co., Berlin. Fisher and Heintz, 
 of Philadelphia, also make excellent thermometers. 
 
 The scales of the mercurial thermometers are made 
 to range as high as 600° F., and for convenience are 
 sometimes graduated on one side of the stem with the 
 Centigrade and on the other with the Fahrenheit 
 scale. Fahrenheit's degrees being small, have the ad- 
 
142 
 
 DIFFERENTIAL THERMOMETERS. 
 
 Fig. 85. 
 
 ^ Q 
 
 ^ 
 
 vantage over the others of not giving fractional parts, which 
 are inconvenient in calculation. The laboratory should be 
 supplied with two or more of these apparatus. 
 
 Air thermometers are sometimes used, and though very 
 delicate, are less convenient than those of mercury and 
 alcohol, and liable to objections which do not attach to the 
 latter. 
 
 Leslie's diflFerential thermometer, Fig. 85, which is a modi- 
 fication of the air thermometer, is now fre- 
 quently used in researches for determining 
 very small difierences in temperature. It 
 consists of an U tube with a hollow bulb 
 blown at each end and closed, so that the 
 fluid within (sulphuric acid, colored with car- 
 mine to render it more visible) is entirely 
 free from external atmospheric pressure. 
 This instrument does not exhibit a change 
 of temperature except by the difference be- 
 tween the elasticity of the air in the two 
 
 ^ bulbs, and therefore indicates only such 
 
 temperatures as affect one bulb and not the 
 other. When both bulbs are of equal temperature, the liquid 
 within remains stationary, but so soon as one becomes warmer 
 than the other the fluid recedes to the opposite bulb, and the 
 scale attached to one of the legs is so graduated as to measure 
 the comparative degree of heat thus occasioned. 
 
 Melloni's thermo-multiplicator (Miiller, p. 541), is another 
 instrument for the indication of changes of temperature. 
 
 Another convenient instrument, especially in meteorological 
 observations, is the thermometrograph. It is so constructed 
 as to register the maximum and minimum temperatures occur- 
 ring during an interval, and hence the presence of the ope- 
 rator is not necessary to note them at the moment of their 
 occurrence. 
 
 The apparatus which is shown in Fig. 86, consists of a mer- 
 
 Fig. 86. 
 
 mmmm^ 
 
 iiMiiiimiiTTr 
 
 HMH'iiiHimiiiniin 
 
THERMO-MULTIPLICATOR — THBRMOMETROGRAPH. 143 
 
 curial and a spirit thermometer placed horizontally and paral- 
 lel to each other. A steel pin enclosed in the tube of the 
 former is pushed before the column of mercury when the 
 metal in the bulb expands, but remains fixed when it again 
 recedes on cooling, and thus indicates at that point the maxi- 
 mum temperature which has occurred during any interval. 
 
 The corresponding rod, enclosed in the tube of the spirit 
 thermometer, of glass, colored to render it more visible, is 
 not advanced by the expansion of the spirit, but retreats 
 with the column as it contracts to the last point reached by 
 it, and thus registers the minimum of temperature during a 
 certain time, at the degree coincident with its inner end. 
 
 When this instrument is to be used, it must be inclined in 
 such a position as to allow the steel rod to descend to the 
 column of mercury, and the glass rod to the end of the spi- 
 rituous column. The arrangement of the bulbs in opposite 
 positions is with a view to this object. After the rods have 
 reached their proper situations, we may, by placing the in- 
 strument horizontally any morning or evening, obtain at the 
 end of the following 24 hours, the maximum and minimum 
 temperature of that interval. 
 
 There are some very excellent remarks by Regnault upon 
 the relative advantages of the different modes of measuring 
 temperature, to which the student may advantageously refer. 
 
 The translation of his several papers on the subject, is to 
 be found in the Franklin Institute Journal for 1848. 
 
 The following table shows the corresponding degrees of 
 Fahrenheit's, Reaumur's, and the Centigrade thermometers. 
 
144 
 
 THERMOMETRICAL EQUIVALENTS. 
 
 
 s ^ 
 
 
 
 S t^ 
 
 1 
 
 
 3 C 
 
 . 4} 
 
 
 S u 
 
 1 ^ 
 
 .J;T3 
 
 |2 
 
 f^ 
 
 6^ 
 
 P 
 
 a 3 
 
 IM 
 
 n 
 
 ed s 
 
 1^ 
 
 SI 
 
 
 |E> 
 
 600 
 
 252.4! 315.5 
 
 568.4 
 
 238.4 
 
 298 
 
 538 
 
 224.9 
 
 281.1 
 
 506 7 
 
 211 
 
 263.7 
 
 599 
 
 252 316 
 
 668 
 
 238.2 
 
 297.7 
 
 537.8 224.8 
 
 281 
 
 506 
 
 210.6 
 
 263.3 
 
 698 
 
 251.5 314.4 i 
 
 667.5 
 
 238 
 
 297.6 j 
 
 537 1 224.4 
 
 280.5 
 
 505.4 
 
 210.4 
 
 263 
 
 697.2 
 
 251.2 314 i 
 
 667 
 
 237.7 
 
 297.2 ; 
 
 536 224 
 
 280 
 
 505 
 
 210.2 
 
 262.7 
 
 .097 
 
 251.1 313.8! 
 
 566.6 
 
 237.6 
 
 297 i 
 
 535 223.5 
 
 279.4 
 
 604.5 
 
 210 
 
 262.5 
 
 596.7 
 
 251 ! 313.7! 
 
 566 
 
 237.3 
 
 296.6 
 
 534.21223.2 
 
 279 
 
 504 
 
 209.7 
 
 262.2 
 
 696 
 
 250.3: 313.3 
 
 665.2 
 
 237 
 
 296.2 : 
 
 534 i 223.1 
 
 278.8 
 
 .503.6 
 
 209.6 
 
 262 
 
 695.4 
 
 250.4 313 1 
 
 665 
 
 236.9 
 
 296.1 
 
 533.7 223 
 
 278.7 
 
 503 
 
 209.3 
 
 261.6 
 
 595 
 
 250.2; 312.7 
 
 564.8 
 
 236.8 
 
 296 ; 
 
 633 1 222.6 
 
 278.3 
 
 502.2 
 
 209 
 
 261.2 
 
 594.5 
 
 250 s 312.5 1 
 
 564 
 
 236.4 
 
 295.5 
 
 632.4 1 222.4 
 
 278 
 
 502 
 
 208.9 
 
 261.1 
 
 594 
 
 249.7 312.21 
 
 563 
 
 236 
 
 295 i 
 
 532 
 
 222.2 
 
 277.7 
 
 501.8 
 
 208.8 
 
 261 
 
 593.6 
 
 249.6 312 1 
 
 662 
 
 235.5 
 
 294.4 
 
 .531.5 
 
 222 
 
 277.5 
 
 501 
 
 208.4 
 
 260.5 
 
 593 
 
 249.3! 311.6 1 
 
 661.2 
 
 235.2 
 
 294 1 
 
 531 
 
 221.7 
 
 277.2 
 
 500 
 
 208 
 
 260 
 
 592.2 
 
 249 i311.2 
 
 661 
 
 235.1 
 
 293.8 
 
 530.6 
 
 221.6 
 
 277 
 
 499 
 
 207.5 
 
 259.4 
 
 692 
 
 248.9! 311.1 1 
 
 660.7 
 
 235 
 
 293.7 
 
 630 
 
 221.3 
 
 276.6 
 
 498.2 
 
 207.2 
 
 259 
 
 •OP 1.8 
 
 248.8,311 
 
 660 
 
 234.6 
 
 293.3 
 
 529.2 
 
 221 
 
 276.2 
 
 498 
 
 207.1 
 
 258.8 
 
 691 
 
 248.4 310.5 
 
 559.4 
 
 234.4 
 
 293 
 
 529 
 
 220.9 
 
 276.1 
 
 497.7 
 
 207 
 
 258.7 
 
 690 
 
 24S 1310 
 
 559 
 
 234.2 
 
 292.7 
 
 528.8 
 
 220 8 
 
 276 
 
 497 
 
 206.6 
 
 258.3 
 
 589 
 
 247.5 309.4 
 
 658.5 
 
 234 
 
 292.5 ; 
 
 528 
 
 220.4 
 
 275.6 
 
 496.4 
 
 206.4 
 
 258 
 
 588.2 
 
 247.2 
 
 309 
 
 558 
 
 233.7 
 
 292.2 
 
 527 
 
 220 
 
 276 
 
 496 
 
 206.2 
 
 257.7 
 
 588 
 
 247.1 
 
 308.8 ! 
 
 557.6 
 
 233.6 
 
 292 ! 
 
 526 
 
 219.5 
 
 274.4 
 
 495.5 
 
 206 
 
 257.5 
 
 587.7 
 
 247 
 
 308.7 i 
 
 557 
 
 233.3 
 
 291.6 1 
 
 525.2 
 
 219.2 
 
 274 
 
 495 
 
 205 7 
 
 257.2 
 
 587 
 
 246.6 
 
 308.3 
 
 5.56.2 
 
 233 
 
 291.2; 
 
 525 
 
 219.1 
 
 273.8 
 
 494.6 
 
 205.6 
 
 257 
 
 686.4 
 
 246.4 
 
 308 
 
 556 
 
 232.9 
 
 291.1 
 
 524.7 
 
 219 
 
 273.7 
 
 494 
 
 205.3 
 
 256.6 
 
 586 
 
 246.2 
 
 307.7 
 
 555.8 
 
 232.8 
 
 291 
 
 624 
 
 218.6 
 
 273.3 
 
 493.2 
 
 205 
 
 256.2 
 
 585.6 
 
 246 
 
 307.5 
 
 555 
 
 232.4 
 
 290.5 
 
 523.4 
 
 218.4 
 
 273 
 
 493 
 
 204.9 
 
 256.1 
 
 685 
 
 245.7 
 
 307.2 
 
 554 
 
 232 
 
 290 1 
 
 523 
 
 218.2 
 
 272.7 
 
 492.8 
 
 204.8 
 
 256 
 
 584.6 
 
 245.6 
 
 307 
 
 553 
 
 231.5 
 
 289.4 
 
 522.5 
 
 218 
 
 272.5 
 
 492 
 
 204.4 
 
 255.5 
 
 684 
 
 245.3 
 
 306.6 
 
 552.2 
 
 231.2 
 
 289 
 
 622 
 
 217.7 
 
 272.2 
 
 491 
 
 204 
 
 265 
 
 683.2 
 
 245 
 
 306.2 
 
 652 
 
 231.1 
 
 288.8 
 
 621.6 
 
 217.6 
 
 272 
 
 490 
 
 203.5 
 
 264.4 
 
 683 
 
 244.9 
 
 306.1 
 
 651.7 
 
 231 
 
 288.7 
 
 621 
 
 217.3 
 
 271.6 
 
 489.2 
 
 203.2 
 
 254 
 
 682.8 
 
 244.8 
 
 306 
 
 551 
 
 230.6 
 
 288.3 
 
 520.2 
 
 217 
 
 271.2 
 
 489 
 
 203.1 
 
 253.8 
 
 682 
 
 244.4 
 
 305.5 
 
 550.4 
 
 230.4 
 
 288 
 
 520 
 
 216.9 
 
 271.1 
 
 488.7 
 
 203 
 
 253.7 
 
 681 
 
 244 
 
 305 
 
 550 
 
 230.2 
 
 287.7 
 
 519.8 
 
 216.8 
 
 271 
 
 488 
 
 202.6 
 
 253.3 
 
 580 
 
 243.5 
 
 304.4 
 
 649.5 
 
 230 
 
 287.5 
 
 519 
 
 216.4 
 
 270.5 
 
 487.4 
 
 202.4 
 
 253 
 
 .679.2 
 
 243.2 
 
 304 
 
 649 
 
 229.7 
 
 287.2 
 
 518 
 
 216 
 
 270 
 
 487 
 
 202.2 
 
 252.7 
 
 .579 
 
 243.1 
 
 303.8 
 
 548.6 
 
 229.6 
 
 287 
 
 517 
 
 215.5 
 
 269.4 
 
 486.5 
 
 202 
 
 252.5 
 
 678.7 
 
 243 
 
 303.7 
 
 548 
 
 229.3 
 
 286.6 
 
 616.2 
 
 215.2 
 
 269 
 
 486 
 
 201.7 
 
 2.52.2 
 
 678 
 
 242.6 
 
 303.3 
 
 .547.2 
 
 229 
 
 286.2 
 
 516 
 
 215.1 
 
 268.8 
 
 485.6 
 
 201.6 
 
 252 
 
 577.4 
 
 242.4 
 
 303 
 
 547 
 
 228.9 
 
 286.1 
 
 515.7 
 
 215 
 
 268.7 
 
 485 
 
 201.3 
 
 251.6 
 
 577 
 
 242.2 
 
 302.7 
 
 646.8 
 
 228.8 
 
 286 
 
 515 
 
 214.6 
 
 268.3 
 
 484.2 
 
 201 
 
 251.2 
 
 676.5 
 
 242 
 
 302.5 
 
 546 
 
 228.4 
 
 285.5 
 
 514.4 
 
 214.4 
 
 268 
 
 484 
 
 200.9 
 
 251.1 
 
 576 
 
 241.7 
 
 302.2 
 
 545 
 
 228 
 
 285 
 
 514 
 
 214.2 
 
 267.7 
 
 483.8 
 
 200.8 
 
 251 
 
 576.6 
 
 241.6 
 
 302 
 
 544 
 
 227.6 
 
 284.4 
 
 613.5 
 
 214 
 
 267.5 
 
 483 
 
 200.4 
 
 250.5 
 
 676 
 
 241.3 
 
 301.6 
 
 643.2 
 
 227.2 
 
 284 
 
 613 
 
 213.7 
 
 267.2 
 
 482 
 
 200 
 
 250 
 
 674.2 
 
 241 
 
 301.2 
 
 543 
 
 227.1 
 
 283.8 
 
 612.6 
 
 213.6 
 
 267 
 
 481 
 
 199.5 
 
 249.4 
 
 674 
 
 240.9 
 
 301.1 
 
 542.7 
 
 227 
 
 283.7 
 
 512 
 
 213.3 
 
 266.6 
 
 480.2 
 
 199.2 
 
 249 
 
 673.8 
 
 240.8 
 
 301 
 
 542 
 
 226.6 
 
 283.3 
 
 611.2 
 
 213 
 
 266.2 
 
 480 
 
 199.1 
 
 248.8 
 
 673 
 
 240.4 
 
 300.5 
 
 541.4 
 
 226.4 
 
 283 
 
 511 
 
 212.9 
 
 266.1 
 
 479.7 
 
 199 
 
 248.7 
 
 672 
 
 240 
 
 300 
 
 541 
 
 226.2 
 
 282.7 
 
 510.8 
 
 212.8 
 
 266 
 
 479 
 
 198.6 
 
 248.3 
 
 571 
 
 239.5 
 
 299.4 
 
 540.5 
 
 226 
 
 282.5 
 
 510 
 
 212.4 
 
 265.5 
 
 478.4 
 
 198.4 
 
 248 
 
 670.2 
 
 239.2 
 
 299 
 
 540 
 
 225.7 
 
 282.2 
 
 509 
 
 212 
 
 265 
 
 478 
 
 198.2 
 
 247.7 
 
 670 
 
 239.1 
 
 298.8 
 
 539.6 
 
 225.6 
 
 282 
 
 508 
 
 211.6 
 
 264.4 
 
 477.5 
 
 198 
 
 247.5 
 
 669.7 
 
 239 
 
 298.7 
 
 639 
 
 225.3 
 
 281.6 
 
 607.2 
 
 211.2 
 
 264 
 
 477 
 
 197.7 
 
 247.2 
 
 669 
 
 238.6 
 
 298.3 
 
 538.2 
 
 225 
 
 281.2 
 
 507 
 
 211.1 
 
 263.8 
 
 476.6 
 
 197.6 
 
 247 
 
THERMOMETRICAL EQUIVALENTS. 
 
 145 
 
 
 a u 
 
 • ■-T3 
 
 
 3 u 
 
 .i| 
 
 a 
 £- 
 
 a u 
 
 ■a^ 
 
 
 a C 
 
 •i| 
 
 j= "S 
 
 cd S 
 
 c 2 
 
 .a-S 
 
 el S 
 
 a g 
 
 "^'3 
 
 a 3 
 
 a 2 
 
 X'S 
 
 cd 3 
 
 a S 
 
 ;^- 
 
 ^s 
 
 «£b 
 
 ^- 
 
 ^s 
 
 ^- 
 
 ^^ 
 
 (2S 
 
 6^ 
 
 £- 
 
 <2s 
 
 «s, 
 
 476 
 
 197.3 
 
 246.6 
 
 444.2 
 
 183.2 
 
 229 
 
 414 
 
 169.7 
 
 212.2 
 
 383 
 
 156 
 
 195 
 
 475.2 
 
 197 
 
 246.2 
 
 444 
 
 183.1 
 
 228.8 
 
 413.6 
 
 169.6 
 
 212 
 
 382 
 
 155.5 
 
 194.4 
 
 475 
 
 196.9 
 
 246.1 
 
 443.7 
 
 183 
 
 228.7 
 
 413 
 
 169.3 
 
 211.6 
 
 381.2 
 
 155.2 
 
 194 
 
 474.8 
 
 196.8 
 
 246 
 
 443 
 
 182.6 
 
 228.3 
 
 412.2 
 
 169 
 
 211.2 
 
 381 
 
 155.1 
 
 193.8 
 
 474 
 
 196.4 
 
 245.5 
 
 442.4 
 
 182.4 
 
 228 
 
 412 
 
 168.9 
 
 211.1 
 
 380.7 
 
 155 
 
 193.7 
 
 473 
 
 196 
 
 245 
 
 442 
 
 182.2 
 
 227.7 
 
 411.8 
 
 168.8 
 
 211 
 
 380 
 
 154.6 
 
 193.3 
 
 472 
 
 195.5 
 
 244.4 
 
 441.5 
 
 182 
 
 227.5 
 
 411 
 
 168.4 
 
 210.5 
 
 379.4 
 
 154.4 
 
 193 
 
 471.2 
 
 195.2 
 
 244 
 
 441 
 
 181.7 
 
 227.2 
 
 410 
 
 168 
 
 210 
 
 379 
 
 154.2 
 
 192.7 
 
 471 
 
 195.1 
 
 243.8 
 
 440.6 
 
 181.6 
 
 227 
 
 409 
 
 167.5 
 
 209.4 
 
 378.5 
 
 154 
 
 192.5 
 
 470.7 
 
 195 
 
 243.7 
 
 440 
 
 181.3 
 
 226.6 
 
 408.2 
 
 167.2 
 
 209 
 
 378 
 
 153.7 
 
 192.2 
 
 470 
 
 194.6 
 
 243.3 
 
 439.2 
 
 181 
 
 226 2 
 
 408 
 
 167.1 
 
 208.8 
 
 377.6 
 
 153.6 
 
 192 
 
 469.4 
 
 194.4 
 
 243 
 
 439 
 
 180.9 
 
 226.1 
 
 407.7 
 
 167 
 
 208.7 
 
 377 
 
 153.3 
 
 191.6 
 
 469 
 
 194.2 
 
 242.7 
 
 438.8 
 
 180.8 
 
 226 
 
 407 
 
 166.6 
 
 208.3 
 
 376.2 
 
 153 
 
 191.2 
 
 468.5 
 
 194 
 
 242.5 
 
 438 
 
 180.4 
 
 225.5 
 
 406.4 
 
 166.4 
 
 208 
 
 376 
 
 152.9 
 
 191.1 
 
 468 
 
 193.7 
 
 242.2 
 
 437 
 
 180 
 
 225 
 
 406 
 
 166.2 
 
 207.7 
 
 375.8 
 
 152.8 
 
 191 
 
 467.6 
 
 193.6 
 
 242 
 
 436 
 
 179.5 
 
 224.4 
 
 405.5 
 
 166 
 
 207.5 
 
 375 
 
 152.4 
 
 190.5 
 
 467 
 
 193.3 
 
 241.6 
 
 435.2 
 
 179.2 
 
 224 
 
 405 
 
 165.7 
 
 207.2 
 
 374 
 
 152 
 
 190 
 
 466.2 
 
 193 
 
 241.2 
 
 435 
 
 179.1 
 
 223.8 
 
 404.6 
 
 165.6 
 
 207 
 
 373 
 
 151.5 
 
 189.4 
 
 466 
 
 192.9 
 
 241.1 
 
 434.7 
 
 179 
 
 223.7 
 
 404 
 
 165.3 
 
 206.6 
 
 372.2 
 
 151.2 
 
 189 
 
 465.8 
 
 192.8 
 
 241 
 
 434 
 
 178.6 
 
 223.3 
 
 403.2 
 
 165 
 
 206.2 
 
 372 
 
 151.1 
 
 188.8 
 
 465 
 
 192.4 
 
 240.5 
 
 433.4 
 
 178.4 
 
 223 
 
 403 
 
 164.9 
 
 206.1 
 
 371.7 
 
 151 
 
 188.7 
 
 464 
 
 192 
 
 240 
 
 433 
 
 178.2 
 
 222.7 
 
 402.8 
 
 164.8 
 
 206 
 
 371 
 
 150.6 
 
 188.3 
 
 463 
 
 191.5 
 
 239.4 
 
 432.5 
 
 178 
 
 222.5 
 
 402 
 
 164.4 
 
 205.5 
 
 370.4 
 
 150.4 
 
 188 
 
 462.2 
 
 191.2 
 
 239 j 
 
 432 
 
 177.7 
 
 222.2 
 
 401 
 
 164 
 
 205 
 
 370 
 
 150.2 
 
 187.7 
 
 462 
 
 191.1 
 
 238.8 
 
 431.6 
 
 177.6 
 
 222 
 
 400 
 
 163.5 
 
 204.4 
 
 369.5 
 
 150 
 
 187.5 
 
 461.7 
 
 191 
 
 238.7 
 
 431 
 
 177.3 
 
 221.6 
 
 399.2 
 
 163.2 
 
 204 
 
 369 
 
 149.7 
 
 187.2 
 
 461 
 
 190.6 
 
 238.3 
 
 430.2 
 
 177 
 
 221.2 
 
 399 
 
 163.1 
 
 203.8 
 
 368.6 
 
 149.6 
 
 187 
 
 460.4 
 
 190.4 
 
 238 
 
 430 
 
 176.9 
 
 221.1 
 
 398.7 
 
 163 
 
 203.7 
 
 368 
 
 149.3 
 
 186.6 
 
 460 
 
 190.2 
 
 237.7 
 
 429.8 
 
 176.8 
 
 221 
 
 398 
 
 162.6 
 
 203.3 
 
 367.2 
 
 149 
 
 186.2 
 
 459.5 
 
 190 
 
 237.5 I 
 
 429 
 
 176.4 
 
 220.5 
 
 397.4 
 
 162.4 
 
 203 
 
 367 
 
 148.9 
 
 186.1 
 
 459 
 
 1S9.7 
 
 237.2 1 
 
 428 
 
 176 
 
 220 
 
 397 
 
 162.2 
 
 202.7 
 
 366.8 
 
 148.8 
 
 186 
 
 458.6 
 
 189.6 
 
 237 
 
 427 
 
 175.5 
 
 219.4 
 
 396.5 
 
 162 
 
 202.5 
 
 366 
 
 148.4 
 
 185.5 
 
 458 
 
 189.3 
 
 236.6 
 
 426.2 
 
 175.2 
 
 219 
 
 396 
 
 161.7 
 
 202.2 
 
 365 
 
 148 
 
 185 
 
 457.2 
 
 189 
 
 236.2 
 
 426 
 
 175.1 
 
 218.8 
 
 395.6 
 
 161.6 
 
 202 
 
 364 
 
 147.5 
 
 184.4 
 
 457 
 
 188.9 
 
 236.1 
 
 425.7 
 
 175 
 
 218.7 
 
 395 
 
 161.3 
 
 201.6 
 
 363.2 
 
 147.2 
 
 184 
 
 4.56.8 
 
 188.8 
 
 236 
 
 425 
 
 174.6 
 
 218.3 
 
 394.2 
 
 161 
 
 201.2 
 
 363 
 
 147.1 
 
 183.8 
 
 456 
 
 188.4 
 
 235.5 
 
 424.4 
 
 174.4 
 
 218 ! 
 
 394 
 
 160.9 
 
 201.1 
 
 362.7 
 
 147 
 
 183.7 
 
 455 
 
 188 
 
 235 
 
 424 
 
 174.2 
 
 217.7 
 
 393.8 
 
 160.8 
 
 201 
 
 362 
 
 146.6 
 
 183.3 
 
 454 
 
 187.5 
 
 234.4 
 
 423.5 
 
 174 
 
 217.5 
 
 393 
 
 160.4 
 
 200.5 
 
 361.4 
 
 146.4 
 
 183 
 
 453.2 
 
 187.2 
 
 234 
 
 423 
 
 173.7 
 
 217.2 
 
 392 
 
 160 
 
 200 
 
 361 
 
 146.2 
 
 182.7 
 
 453 
 
 187.1 
 
 233.8 
 
 422.6 
 
 173.6 
 
 217 
 
 391 
 
 159.5 
 
 199.4 
 
 360.5 
 
 146 
 
 182.5 
 
 452.7 
 
 187 
 
 233.7 
 
 422 
 
 173.3 
 
 216.6 
 
 390.2 
 
 159.2 
 
 199 
 
 }360 
 
 145.7 
 
 182.2 
 
 452 
 
 186.6 
 
 233.3 
 
 421,2 
 
 173 
 
 216.2 
 
 390 
 
 159.1 
 
 198.8 
 
 359.6 
 
 145.6 
 
 182 
 
 451.4 
 
 186.4 
 
 233 1 
 
 421 
 
 172.9 
 
 216.1 
 
 389.7 
 
 1.59 
 
 198.7 
 
 359 
 
 14.5.3 
 
 181.6 
 
 451 
 
 186.2 
 
 232.7 
 
 420.8 
 
 172.8 
 
 216 
 
 389 
 
 158. 6 
 
 198.3 
 
 358.2 
 
 145 
 
 181.2 
 
 450.5 
 
 186 
 
 232.5 
 
 420 
 
 172.4 
 
 215.5 
 
 388.4 
 
 158.4 
 
 198 
 
 358 
 
 144.9 
 
 181.1 
 
 450 
 
 185.7 
 
 232.2 
 
 419 
 
 172 
 
 215 
 
 388 
 
 158.2 
 
 197.7 
 
 357.8 
 
 144.8 
 
 181 
 
 449.6 
 
 185.6 
 
 232 
 
 418 
 
 171.5 
 
 214.4 
 
 387.5 
 
 158 
 
 197.5 
 
 357 
 
 144.4 
 
 180.5 
 
 449 
 
 185.3 
 
 231.6 
 
 417.2 
 
 171.2 
 
 214 
 
 387 
 
 157.7 
 
 197.2 
 
 356 
 
 144 
 
 180 
 
 448.2 
 
 185 
 
 231.2 
 
 417 
 
 171.1 
 
 213.8 
 
 386.6 
 
 157.6 
 
 197 
 
 355 
 
 143.5 
 
 179.4 
 
 448 
 
 184.9 
 
 231.1 
 
 416.7 
 
 171 
 
 213.7 
 
 386 
 
 157.3 
 
 196.6 
 
 354.2 
 
 143.2 
 
 179 
 
 447.8 
 
 184.8 
 
 231 
 
 416 
 
 170.6 
 
 213.3 
 
 385.2 
 
 157 
 
 196.2 
 
 354 
 
 143.1 
 
 178.8 
 
 447 
 
 184.4 
 
 230.5 
 
 415.4 
 
 170.4 
 
 213 
 
 385 
 
 156.9 
 
 196.1 
 
 353.7 
 
 143 
 
 178.7 
 
 446 
 
 184 
 
 230. 
 
 415 
 
 170.2 
 
 212.7 
 
 384.8 
 
 156.8 
 
 196 
 
 353 
 
 142.6 
 
 178.3 
 
 445 
 
 183.5 
 
 229-4 
 
 414.5 
 
 170 
 
 212.6 
 
 384 
 
 156.4 
 
 195.6 
 
 362 4 
 
 142.4 
 
 178 
 
146 
 
 THERMOMETRICAL EQUIVALENTS. 
 
 2:j 
 
 hu 
 
 •il 
 
 
 3 u 
 
 •i| 
 
 
 S u 
 
 •i-S 
 
 
 S t^ 
 
 .^4 
 
 
 e8 a 
 
 c £ 
 
 .c'S 
 
 Ri :i 
 
 = S 
 
 -S'S 
 
 rs s 
 
 s S 
 
 -c-53 
 
 a 2 
 
 c S 
 
 1-^ 
 
 tSS 
 
 6^ 
 
 ^^ 
 
 <SS 
 
 6^ 
 
 (2-^ 
 
 (S2 
 
 «& 
 
 ^^ 
 
 ^^ 
 
 «^ 
 
 352 
 
 142.2 
 
 177.7 
 
 321.8 
 
 128.8 
 
 161 
 
 290 
 
 114.6 
 
 143.3 
 
 259.2 
 
 101 
 
 126.2 
 
 351.5 
 
 142 
 
 177.5 
 
 321 
 
 128.4 
 
 160.5 
 
 289.4 
 
 114.4 
 
 143 
 
 259 
 
 100.8 
 
 126.1 
 
 351 
 
 141.8 
 
 177.2 
 
 320 
 
 128 
 
 460 
 
 289 
 
 114.2 
 
 142.7 
 
 258.8 
 
 100.8 
 
 126 
 
 350.6 
 
 141.6 
 
 177 
 
 319 
 
 127.5 
 
 159.4 
 
 288.5 
 
 114 
 
 142.5 
 
 258 
 
 100.4 
 
 125.6 
 
 350 
 
 141.3 
 
 176.6 
 
 318.2 
 
 127.2 
 
 159 
 
 288 
 
 113.7 
 
 142.2 
 
 257 
 
 100 
 
 125 
 
 349.2 
 
 141 
 
 176.2 
 
 318 
 
 127.1 
 
 158.8 
 
 287.6 
 
 113.6 
 
 142 
 
 256 
 
 99.5 
 
 124.4 
 
 349 
 
 140.9 
 
 176.1 
 
 317.7 
 
 127 
 
 158.7 
 
 287 
 
 113.3 
 
 141.6 
 
 255.2 
 
 99.2 
 
 124 
 
 348.8 
 
 140.8 
 
 176 
 
 317 
 
 126.6 
 
 158.3 
 
 286.2 
 
 113 
 
 141.2 
 
 255 
 
 99.1 
 
 123.8 
 
 348 
 
 140.4 
 
 175.5 
 
 316.4 
 
 126.4 
 
 158 
 
 286 
 
 112.8 
 
 141.1 
 
 254.7 
 
 99 
 
 123.7 
 
 347 
 
 140 
 
 175 
 
 316 
 
 126.2 
 
 157.7 
 
 285.8 
 
 112.8 
 
 141 
 
 254 
 
 98.6 
 
 123.3 
 
 346 
 
 139.5 
 
 174.4 
 
 315.5 
 
 126 
 
 157.5 
 
 285 
 
 112.4 
 
 140.5 
 
 263.4 
 
 98.4 
 
 123 
 
 345.2 
 
 139.2 
 
 174 
 
 315 
 
 125.7 
 
 157.2 
 
 284 
 
 112 
 
 140 
 
 253 
 
 98.2 
 
 122.7 
 
 345 
 
 139.1 
 
 173.8 
 
 314.6 
 
 125.6 
 
 157 
 
 283 
 
 111.5 
 
 139.4 
 
 252.6 
 
 98 
 
 122.5 
 
 344.7 
 
 139 
 
 173.7 
 
 314 
 
 125.3 
 
 156.6 
 
 282.2 
 
 111.2 
 
 139 
 
 252 
 
 97.9 
 
 122.2 
 
 344 
 
 138.6 
 
 173.3 
 
 313.2 
 
 125 
 
 156.2 
 
 282 
 
 111.1 
 
 138.9 
 
 251.6 
 
 97.6 
 
 122 
 
 343.4 
 
 138.4 
 
 173 
 
 313 
 
 124.8 
 
 156.1 
 
 281.7 
 
 111 
 
 138.7 
 
 261 
 
 97.3 
 
 121.6 
 
 343 
 
 138.2 
 
 172.7 
 
 312.8 
 
 124.8 
 
 156 
 
 281 
 
 110.6 
 
 138.3 
 
 260.2 
 
 97 
 
 121.2 
 
 342.5 
 
 138 
 
 172.5 
 
 312 
 
 124.5 
 
 155.5 
 
 280.4 
 
 110.4 
 
 138 
 
 250 
 
 96.9 
 
 121.1 
 
 342 
 
 137.7 
 
 172.2 
 
 311 
 
 124 
 
 155 
 
 280 
 
 110.2 
 
 137.7 
 
 249.8 
 
 96.8 
 
 121 
 
 341.6 
 
 137.6 
 
 172 
 
 310 
 
 123.5 
 
 154.4 
 
 279.5 
 
 110 
 
 137.5 
 
 249 
 
 96.4 
 
 120.5 
 
 341 
 
 137.3 
 
 171.6 
 
 309.2 
 
 123.2 
 
 154 
 
 279 
 
 109.7 
 
 137.2 
 
 248 
 
 96 
 
 120 
 
 340.2 
 
 137 
 
 171.2 
 
 309 
 
 123.1 
 
 153.8 
 
 278.6 
 
 109.6 
 
 137 
 
 247 
 
 95.5 
 
 119.4 
 
 340 
 
 136.9 
 
 171.1 
 
 30S.7 
 
 123 
 
 153.7 
 
 278 
 
 109.3 
 
 136.6 
 
 246.2 
 
 95.2 
 
 119 
 
 339.8 
 
 136.8 
 
 171 
 
 308 
 
 122.6 
 
 153.3 
 
 277.2 
 
 109 
 
 136.2 
 
 246 
 
 95.1 
 
 118.9 
 
 339 
 
 136.4 
 
 170.5 
 
 307.4 
 
 122.4 
 
 153 
 
 277 
 
 108.8 
 
 136.1 
 
 245.7 
 
 95 
 
 118.7 
 
 338 
 
 136 
 
 170 
 
 307 
 
 122.2 
 
 152.7 
 
 276.8 
 
 108.8 
 
 136 
 
 245 
 
 94.6 
 
 118.3 
 
 337 
 
 135.5 
 
 169.4 
 
 306.5 
 
 122 
 
 152.5 
 
 276 
 
 108.4 
 
 135.6 
 
 244.4 
 
 94.4 
 
 118 
 
 336.2 
 
 135.2 
 
 169 
 
 306 
 
 121.7 
 
 152.2 
 
 275 
 
 108 
 
 135 
 
 244 
 
 94.2 
 
 117.8 
 
 336 
 
 135.1 
 
 168.8 
 
 305.6 
 
 121.6 
 
 152 
 
 274 
 
 107.5 
 
 134.4 
 
 243.5 
 
 94 
 
 117.5 
 
 335.7 
 
 135 
 
 168.7 
 
 305 
 
 121.3 
 
 151.6 
 
 273.2 
 
 107.2 
 
 134 
 
 243 
 
 93.8 
 
 117.2 
 
 335 
 
 134.6 
 
 168.3 
 
 304.2 
 
 121 
 
 151.2 
 
 273 
 
 107.1 
 
 133.8 
 
 242.6 
 
 93.6 
 
 117 
 
 334.4 
 
 134.4 
 
 168 
 
 304 
 
 120.9 
 
 151.1 
 
 272.7 
 
 107 
 
 133.7 
 
 242 
 
 93.3 
 
 116.6 
 
 334 
 
 134.2 
 
 167.7 
 
 303.8 
 
 120.8 
 
 151 
 
 272 
 
 106.6 
 
 133.3 
 
 241.2 
 
 93 
 
 116.2 
 
 333.5 
 
 134 
 
 167.5 
 
 303 
 
 12C.4 
 
 150.5 
 
 271.4 
 
 106.4 
 
 133 
 
 241 
 
 92.9 
 
 116.1 
 
 333 
 
 133.7 
 
 167.2 
 
 302 
 
 120 
 
 150 
 
 271 
 
 106.2 
 
 132.7 
 
 240.8 
 
 92.8 
 
 116 
 
 332.6 
 
 133.6 
 
 167 
 
 301 
 
 119.5 
 
 149.4 
 
 270.5 
 
 106 
 
 132.5 
 
 240 
 
 92.4 
 
 115.6 
 
 332 
 
 133.3 
 
 166.6 
 
 300.2 
 
 119.2 
 
 149 
 
 270 
 
 105.7 
 
 132.2 
 
 239 
 
 92 
 
 116 
 
 331.2 
 
 133 
 
 166.2 
 
 300 
 
 119.1 
 
 148.9 
 
 269.6 
 
 105.6 
 
 132 
 
 238 
 
 91.5 
 
 114.4 
 
 331 
 
 132.9 
 
 166.1 
 
 299.7 
 
 119 
 
 148.7 
 
 269 
 
 105.3 
 
 131.6 
 
 237.2 
 
 91.2 
 
 114 
 
 330.8 
 
 132.8 
 
 166 
 
 299 
 
 118.6 
 
 148.3 
 
 268.2 
 
 105 
 
 131.2 
 
 237 
 
 91.1 
 
 113.9 
 
 330 
 
 132.4 
 
 165.5 
 
 298.4 
 
 118.4 
 
 148 
 
 268 
 
 104.8 
 
 131.1 
 
 236.7 
 
 91 
 
 113.7 
 
 329 
 
 132 
 
 165 
 
 298 
 
 118.2 
 
 147.7 
 
 267.8 
 
 104.8 
 
 131 
 
 236 
 
 90.3 
 
 113.3 
 
 328 
 
 131.5 
 
 164.4 
 
 297.5 
 
 118 
 
 147.5 
 
 267 
 
 104.4 
 
 130.5 
 
 235.4 
 
 90.4 
 
 113 
 
 327.2 
 
 131.2 
 
 164 
 
 297 
 
 117.7 
 
 147.2 
 
 266 
 
 104 
 
 130 
 
 235 
 
 90.2 
 
 112.7 
 
 327 
 
 131.1 
 
 163.9 
 
 296.6 
 
 117.6 
 
 147 
 
 265 
 
 103.5 
 
 129.4 
 
 234.5 
 
 90 
 
 112.5 
 
 326.7 
 
 131 
 
 163.7 
 
 296 
 
 117.3 
 
 146.6 
 
 264.2 
 
 103.2 
 
 129 
 
 234 
 
 89.7 
 
 112.2 
 
 326 
 
 130.6 
 
 163.3 
 
 295.2 
 
 117 
 
 146.2 
 
 264 
 
 103.1 
 
 128.9 
 
 233.6 
 
 89.6 
 
 112 
 
 325.4 
 
 130.4 
 
 163 
 
 295 
 
 116.9 
 
 146.1 
 
 263.7 
 
 103 
 
 128.7 
 
 233 
 
 89.3 
 
 111.6 
 
 325 
 
 130.2 
 
 162.7 
 
 294.8 
 
 116.8 
 
 146 
 
 263 
 
 102.6 
 
 128.3 
 
 232.2 
 
 89 
 
 111.2 
 
 324.5 
 
 130 
 
 162.5 
 
 294 
 
 116.4 
 
 145.5 
 
 262.4 
 
 102.4 
 
 128 
 
 232 
 
 88.9 
 
 111.1 
 
 324 
 
 129.7 
 
 162.2 
 
 293 
 
 116 
 
 145 
 
 262 
 
 102.2 
 
 127.7 
 
 231.8 
 
 88.8 
 
 111 
 
 323.6 
 
 129.6 
 
 162 
 
 292 
 
 115.5 
 
 144.4 
 
 261.5 
 
 102 
 
 127.5 
 
 231 
 
 88.4 
 
 110.5 
 
 323 
 
 129.3 
 
 161.6 
 
 291.2 
 
 115.2 
 
 144 
 
 261 
 
 101.7 
 
 127.2 
 
 230 
 
 88 
 
 110 
 
 322.2 
 
 129 
 
 161.2 
 
 291 
 
 115.1 
 
 143.8 
 
 260.6 
 
 101.6 
 
 127 
 
 229 
 
 87.5 
 
 109.4 
 
 322 
 
 128.8 
 
 161.1 
 
 290.7 
 
 115 
 
 143.7 
 
 260 
 
 101.3 
 
 126.6 
 
 228.2 
 
 87.2 
 
 109 
 
THERMOMETRICAL EQUIVALENTS. 
 
 14T 
 
 L 
 
 i u 
 
 ii 
 
 a 
 
 9 u 
 
 
 
 =■ ^ 
 
 1 4) 
 
 •-T3 
 
 
 => u 
 
 ■i^ 
 
 
 a 9 
 
 j= s 
 
 a a 
 
 c S 
 
 ■>s'Z 
 
 a 3 
 
 fl s 
 
 JS-tJ 
 
 cd a 
 
 si 
 
 O bo 
 
 t'^ 
 
 ^s 
 
 6^ 
 
 £^ 
 
 ^a 
 
 6^ 
 
 ^^ 
 
 tfS 
 
 a^ 
 
 ^•2 
 
 ^s 
 
 228 
 
 87.1 
 
 108.9 
 
 197.6 
 
 73.6 
 
 92 
 
 166 
 
 59.5 
 
 74.4 
 
 135.5 
 
 46 
 
 57.5 
 
 227.7 
 
 87 
 
 108.7 
 
 197 
 
 73.3 
 
 91.6 
 
 165.2 
 
 59.2 
 
 74 
 
 135 
 
 45.8 
 
 57.2 
 
 227 
 
 86.6 
 
 108.3 
 
 196.2 
 
 73 
 
 91.2 
 
 165 
 
 69.1 
 
 73.9 
 
 134.6 
 
 45.6 
 
 57 
 
 226.4 
 
 86.4 
 
 108 
 
 196 
 
 72.8 
 
 91.1 
 
 164.7 
 
 69 
 
 73.7 
 
 134 
 
 46.3 
 
 66.6 
 
 226 
 
 86.2 
 
 107.8 
 
 195.8 
 
 72.8 
 
 91 
 
 164 
 
 68.6 
 
 73.3 
 
 133.2 
 
 45 
 
 56.2 
 
 225.5 
 
 86 
 
 107.5 
 
 195 
 
 72.4 
 
 90.5 
 
 163.4 
 
 58.4 
 
 73 
 
 133 
 
 44.9 
 
 56.1 
 
 225 
 
 85.7 
 
 107.2 
 
 194 
 
 72 
 
 90 
 
 163 
 
 58.2 
 
 72.7 
 
 132.8 
 
 44.8 
 
 66 
 
 224.6 
 
 85.6 
 
 107 
 
 193 
 
 71.5 
 
 89.4 
 
 162.5 
 
 58 
 
 72.6 
 
 132 
 
 44.5 
 
 65.5 
 
 224 
 
 85.3 
 
 106.6 
 
 192.2 
 
 71.2 
 
 89 
 
 162 
 
 67.7 
 
 72.2 
 
 131 
 
 44 
 
 55 
 
 223.2 
 
 85 
 
 106.2 
 
 192 
 
 71.1 
 
 88.8 
 
 161.6 
 
 67.6 
 
 72 
 
 130 
 
 43.5 
 
 54.4 
 
 223 
 
 84.9 
 
 106.1 
 
 191.7 
 
 71 
 
 88.7 
 
 161 
 
 57.3 
 
 71.6 
 
 129.2 
 
 43.2 
 
 54 
 
 222.8 
 
 84.8 
 
 106 
 
 191 
 
 70.6 
 
 88.3 
 
 160.2 
 
 57 
 
 71.2 
 
 129 
 
 43.1 
 
 53.9 
 
 222 
 
 84.4 
 
 105.5 
 
 190.4 
 
 70.4 
 
 88 
 
 160 
 
 56.8 
 
 71.1 
 
 128.7 
 
 43 
 
 53.7 
 
 221 
 
 84 
 
 105 
 
 190 
 
 70.2 
 
 87.8 
 
 159.8 
 
 56.8 
 
 71 
 
 128 
 
 42.6 
 
 53.3 
 
 220 
 
 83.5 
 
 104.4 
 
 189.5 
 
 70 
 
 87.5 
 
 159 
 
 56.4 
 
 70.5 
 
 127.4 
 
 42.4 
 
 53 
 
 219.2 
 
 83.2 
 
 104 
 
 189 
 
 69.7 
 
 87.2 
 
 158 
 
 56 
 
 70 
 
 127 
 
 42.2 
 
 52.7 
 
 219 
 
 83.1 
 
 103.9 
 
 188.6 
 
 69.6 
 
 87 
 
 157 
 
 55.6 
 
 69.4 
 
 126.6 
 
 42 
 
 62.5 
 
 218.7 
 
 83 
 
 103.7 
 
 188 
 
 69.3 
 
 86.6 
 
 156.2 
 
 56.2 
 
 69 
 
 126 
 
 41.8 
 
 62.2 
 
 218 
 
 82.6 
 
 103.3 
 
 187.2 
 
 69 
 
 86.2 
 
 156 
 
 55.1 
 
 68.9 
 
 126.6 
 
 41.6 
 
 62 
 
 217.4 
 
 82.4 
 
 103 
 
 187 
 
 68.9 
 
 86.1 
 
 165.7 
 
 55 
 
 68.7 
 
 125 
 
 41.3 
 
 51.6 
 
 217 
 
 82.2 
 
 102.7 
 
 186.8 
 
 68.8 
 
 86 
 
 155 
 
 54.6 
 
 68.3 
 
 124.2 
 
 41 
 
 51.2 
 
 216.6 
 
 82 
 
 102.6 
 
 186 
 
 68.4 
 
 85.5 
 
 154.4 
 
 54.4 
 
 68 
 
 124 
 
 40.9 
 
 61.1 
 
 216 
 
 81.7 
 
 102.2 
 
 185 
 
 68 
 
 85 
 
 154 
 
 54.2 
 
 67.7 
 
 123.8 
 
 40.8 
 
 51 
 
 215.6 
 
 81.6 
 
 102 
 
 184 
 
 67.5 
 
 84.4 
 
 163.6 
 
 64 
 
 67.5 
 
 123 
 
 40.4 
 
 50.5 
 
 215 
 
 81.3 
 
 101.6 
 
 183.2 
 
 67.2 
 
 84 
 
 153 
 
 63.7 
 
 67.2 
 
 122 
 
 40 
 
 50 
 
 214.2 
 
 81 
 
 101.2 
 
 183 
 
 67.1 
 
 83.9 
 
 162.6 
 
 63.6 
 
 67 
 
 121 
 
 39.5 
 
 49.4 
 
 214 
 
 80.9 
 
 101.1 
 
 182.7 
 
 67 
 
 83.7 
 
 162 
 
 63.3 
 
 66.6 
 
 120.2 
 
 39.2 
 
 49 
 
 213.8 
 
 80.8 
 
 101 
 
 182 
 
 66.6 
 
 83.3 
 
 151.2 
 
 53 
 
 66.2 
 
 120 
 
 39.1 
 
 48.9 
 
 213 
 
 80.4 
 
 100.6 
 
 181.4 
 
 66.4 
 
 83 
 
 151 
 
 62.9 
 
 66.1 
 
 119.7 
 
 39 
 
 48.7 
 
 212 
 
 80 
 
 100 
 
 181 
 
 66.2 
 
 82.7 
 
 160.8 
 
 62.8 
 
 QQ 
 
 119 
 
 38.6 
 
 48.3 
 
 211 
 
 79.5 
 
 99.4 
 
 180.5 
 
 66 
 
 82.5 
 
 160 
 
 62.4 
 
 65.5 
 
 118.4 
 
 38.4 
 
 48 
 
 210.2 
 
 79.2 
 
 99 
 
 180 
 
 65.7 
 
 82.2 
 
 149 
 
 52 
 
 65 
 
 118 
 
 38.2 
 
 47.7 
 
 210 
 
 79.1 
 
 98.9 
 
 179.6 
 
 65.6 
 
 82 
 
 148 
 
 51.5 
 
 64.4 
 
 117.5 
 
 38 
 
 47.5 
 
 209.7 
 
 79 
 
 98.7 
 
 179 
 
 65.3 
 
 81.6 
 
 147.2 
 
 51.2 
 
 64 
 
 117 
 
 37.7 
 
 47.2 
 
 209 
 
 78.6 
 
 98.3 
 
 178.2 
 
 65 
 
 81.2 
 
 147 
 
 61.1 
 
 63.9 
 
 116.6 
 
 37.6 
 
 47 
 
 208.4 
 
 78.4 
 
 98.0 
 
 178 
 
 64.9 
 
 81.1 
 
 146.7 
 
 61 
 
 63.7 
 
 116 
 
 37.3 
 
 46.6 
 
 208 
 
 78.2 
 
 97.8 
 
 177.8 
 
 64.8 
 
 81 
 
 146 
 
 50.6 
 
 63.3 
 
 115.2 
 
 37 
 
 46.2 
 
 207.5 
 
 78 
 
 97.5 
 
 177 
 
 64.4 
 
 80.6 
 
 145.4 
 
 50.4 
 
 63 
 
 115 
 
 36.9 
 
 46.1 
 
 207 
 
 77.7 
 
 97.2 
 
 176 
 
 64 
 
 80 
 
 145 
 
 50.2 
 
 62.7 
 
 114.8 
 
 36.8 
 
 46 
 
 206.6 
 
 77.6 
 
 97 
 
 175 
 
 63.5 
 
 79.4 
 
 144.5 
 
 50 
 
 62.5 
 
 114 
 
 36.4 
 
 45.5 
 
 206 
 
 77.3 
 
 96.6 
 
 174.2 
 
 63.2 
 
 79 
 
 144 
 
 49.7 
 
 62.2 
 
 113 
 
 36 
 
 45 
 
 205.2 
 
 77 
 
 96.2 
 
 174 
 
 63.1 
 
 78.8 
 
 143.6 
 
 49.6 
 
 62 
 
 112 
 
 35.5 
 
 44.4 
 
 205 
 
 76.9 
 
 96.1 
 
 173.7 
 
 63 
 
 78.7 
 
 143 
 
 49.3 
 
 61.6 
 
 111.2 
 
 35.2 
 
 44 
 
 204.8 
 
 76.8 
 
 96 
 
 173 
 
 62.6 
 
 78.3 
 
 142.2 
 
 49 
 
 61.2 
 
 111 
 
 35.1 
 
 43.9 
 
 204 
 
 76.4 
 
 95.5 
 
 172.4 
 
 62.4 
 
 78 
 
 142 
 
 48.9 
 
 61.1 
 
 110.7 
 
 35 
 
 43.7 
 
 203 
 
 76 
 
 95 
 
 172 
 
 62.2 
 
 77.7 
 
 141.8 
 
 48.8 
 
 61 
 
 110 
 
 34.6 
 
 43.3 
 
 202 
 
 75.5 
 
 94.4 
 
 171.5 
 
 62 
 
 77.6 
 
 141 
 
 48.4 
 
 60.5 
 
 109.4 
 
 34.4 
 
 43 
 
 201.2 
 
 75.2 
 
 94 
 
 171 
 
 61.7 
 
 77.2 
 
 140 
 
 48 
 
 60 
 
 109 
 
 34.2 
 
 42.7 
 
 201 
 
 75.1 
 
 93.9 
 
 170.6 
 
 61.6 
 
 77 
 
 139 
 
 47.5 
 
 59.4 
 
 108.5 
 
 34 
 
 42.5 
 
 200.7 
 
 75 
 
 93.7 
 
 170 
 
 61.3 
 
 76.6 
 
 138.2 
 
 47.2 
 
 59 
 
 108 
 
 33.8 
 
 42.2 
 
 200 
 
 74.6 
 
 93.3 
 
 1 169.2 
 
 61 
 
 76.2 
 
 138 
 
 47.1 
 
 58.8 
 
 107.6 
 
 33.6 
 
 42 
 
 199.4 
 
 74.4 
 
 93 
 
 169 
 
 60.8 
 
 76.1 
 
 137.7 
 
 47 
 
 58.7 
 
 107 
 
 33.3 
 
 41.6 
 
 199 
 
 74.2 
 
 92.7 
 
 168.8 
 
 60.8 
 
 76 
 
 137 
 
 46.6 
 
 58.3 
 
 106.2 
 
 33 
 
 41.2 
 
 198.5 
 
 74 
 
 92.5 
 
 168 
 
 60.4 
 
 75.5 
 
 136.4 
 
 46.4 
 
 58 
 
 106 
 
 32.9 
 
 41.1 
 
 198 
 
 73.7 
 
 92.2 
 
 167 
 
 60 
 
 75 
 
 136 
 
 46.2 
 
 57.7 
 
 105.8 
 
 32.8 
 
 41 
 
148 
 
 THERMOMETRICAL EQUIVALENTS. 
 
 
 9 t^ 
 
 •i-S 
 
 
 s i 
 
 
 
 ^ t 
 
 ■ V 
 
 
 3 C 
 
 •i| 
 
 JC*- 
 
 a s 
 
 ■s <a 
 
 ^■- 
 
 a 3 
 
 c £ 
 
 J=-S 
 
 a d 
 
 a £ 
 
 .c-r 
 
 a 3 
 
 — rt 
 
 £- 
 
 ^S 
 
 6^^ 
 
 ^- 
 
 E^S 
 
 6^ 
 
 ^^ 
 
 <o a 
 
 «tc 
 
 ^- 
 
 ^s 
 
 S& 
 
 105 
 
 32.4 
 
 40.5 
 
 73.4 
 
 18.4 
 
 23 
 
 43 
 
 4.9 
 
 6.1 
 
 ! 11.7 
 
 — 9 
 
 —11.2 
 
 104 
 
 32 
 
 40 
 
 73 
 
 18.2 
 
 22.7 
 
 42.8 
 
 4.8 
 
 6 
 
 11 
 
 — 9.3 
 
 —11.6 
 
 103 
 
 31.5 
 
 39.4 
 
 72.5 
 
 18 
 
 22.6 
 
 42 
 
 4.4 
 
 5.5 
 
 10.4 
 
 — 9.6 
 
 —12 
 
 102.2 
 
 31.2 
 
 39 
 
 72 
 
 17,7 
 
 22.2 
 
 41 
 
 4 
 
 5 
 
 10 
 
 — 9.7 
 
 —12.2 
 
 102 
 
 31.1 
 
 38.9 
 
 71.6 
 
 17.6 
 
 22 
 
 40 
 
 3.6 
 
 4.4 
 
 9.5 
 
 —10 
 
 —12.5 
 
 101.7 
 
 31 
 
 38.7 
 
 71 
 
 17.3 
 
 21.6 
 
 39.2 
 
 3.2 
 
 4 
 
 9 
 
 — 10.2 
 
 —12.7 
 
 101 
 
 30.6 
 
 38.3 
 
 70.2 
 
 17 
 
 21.2 
 
 39 
 
 3.1 
 
 3.9 
 
 8.6 
 
 —10.4 
 
 —13 
 
 100.4 
 
 30.4 
 
 38 
 
 70 
 
 16.9 
 
 21.1 
 
 38.7 
 
 3 
 
 3.7 
 
 8 
 
 —10.6 
 
 —13.3 
 
 100 
 
 30.2 
 
 37.7 
 
 69.8 
 
 16.8 
 
 21 
 
 38 
 
 2.6 
 
 3.3 
 
 7.2 
 
 —11 
 
 —13.7 
 
 99.5 
 
 30 
 
 37.5 
 
 69 
 
 16.4 
 
 20.5 
 
 37.4 
 
 2.4 
 
 3 
 
 7 
 
 —11.1 
 
 —13.9 
 
 99 
 
 29.7 
 
 37.2 
 
 68 
 
 16 
 
 20 
 
 37 
 
 2.2 
 
 2.7 
 
 6.8 
 
 —11.2 
 
 —14 
 
 98.6 
 
 29.6 
 
 37 
 
 67 
 
 15.6 
 
 19.4 
 
 36.5 
 
 2 
 
 2.6 
 
 6 
 
 —11.5 
 
 —14.4 
 
 98 
 
 29.3 
 
 36.6 
 
 66.2 
 
 16.2 
 
 19 
 
 36 
 
 1.7 
 
 2.2 
 
 5 
 
 —12 
 
 —15 
 
 97.2 
 
 29 
 
 36.2 
 
 66 
 
 16.1 
 
 18.8 
 
 35.6 
 
 1.6 
 
 2 
 
 4 
 
 —12.4 
 
 —15.5 
 
 97 
 
 28.9 
 
 36.1 
 
 65.7 
 
 16 
 
 18.7 
 
 36 
 
 1.3 
 
 1.6 
 
 3.2 
 
 — 12.8 
 
 —16 
 
 96.8 
 
 28.8 
 
 36 
 
 65 
 
 14.6 
 
 18.3 
 
 34.2 
 
 1 
 
 1.2 
 
 3 
 
 —12.9 
 
 —16.1 
 
 96 
 
 28.4 
 
 35.5 
 
 64.4 
 
 14.4 
 
 18 
 
 34 
 
 0.9 
 
 1.1 
 
 2.7 
 
 —13 
 
 —16.2 
 
 95 
 
 28 
 
 35 
 
 64 
 
 14.2 
 
 17.7 
 
 33.8 
 
 0.8 
 
 I 
 
 2 
 
 —13.3 
 
 —16.6 
 
 94 
 
 27.5 
 
 34.4, 
 
 63.5 
 
 14 
 
 17.5 
 
 33 
 
 0.4 
 
 0.5 
 
 1.4 
 
 —13.6 
 
 — 17 
 
 93.2 
 
 27.2 
 
 34 
 
 63 
 
 13.7 
 
 17.2 
 
 32 
 
 
 
 
 
 1 
 
 —13.7 
 
 —17.2 
 
 93 
 
 27.1 
 
 33.9 
 
 62.6 
 
 13.6 
 
 17 
 
 31 
 
 -0.4 
 
 — 0.5 
 
 0.6 
 
 — 14 
 
 — 17.6 
 
 92.7 
 
 27 
 
 33.7 
 
 62 
 
 13.3 
 
 16.6 
 
 30.2 
 
 -0.8 
 
 — 1 
 
 
 
 —14.2 
 
 -17.7 
 
 92 
 
 26.6 
 
 33.3 
 
 61.2 
 
 13 
 
 16.2 
 
 30 
 
 —0.9 
 
 — 1.1 
 
 — 0.4 
 
 — 14.4 
 
 -18 
 
 91.4 
 
 26.4 
 
 33 
 
 61 
 
 12.9 
 
 16.1 
 
 29.7 
 
 — 1 
 
 — 1.2 
 
 1 
 
 —14.6 
 
 —18.3 
 
 91 
 
 26.2 
 
 32.7 
 
 60.8 
 
 12.8 
 
 16 
 
 29 
 
 —1.3 
 
 — 1.6 
 
 — 1.7 
 
 —15 
 
 —18.7 
 
 90.5 
 
 26 
 
 32.5 
 
 60 
 
 12.4 
 
 15.5 
 
 28.4 
 
 —1.6 
 
 — 2 
 
 — 2 
 
 —15.1 
 
 — 18.9 
 
 90 
 
 25.7 
 
 32.2 
 
 69 
 
 12 
 
 16 
 
 28 
 
 —1.7 
 
 -2.2 
 
 — 2.2 
 
 —15.2 
 
 —19 
 
 89.6 
 
 25.6 
 
 32 
 
 58 
 
 11.5 
 
 14.4 
 
 27.6 
 
 —2 
 
 — 2.5 
 
 — 3 
 
 —15.5 
 
 -19.4 
 
 89 
 
 25.3 
 
 31.6 
 
 67.2 
 
 11.2 
 
 14 
 
 27 
 
 —2.2 
 
 — 2.7 
 
 — 4 
 
 —16 
 
 —20 
 
 88.2 
 
 25 
 
 31.2 
 
 57 
 
 11.1 
 
 13.8 
 
 26.6 
 
 —2.4 
 
 — 3 
 
 — 6 
 
 —16.4 
 
 —20.5 
 
 88 
 
 24.9 
 
 31.1 
 
 66.7 
 
 11 
 
 13.7 
 
 26 
 
 —2.6 
 
 — 3.3 
 
 — 5.8 
 
 — I6.b 
 
 —21 
 
 87.8 
 
 24.8 
 
 31 
 
 56 
 
 10.6 
 
 13.3 
 
 26.2 
 
 —3 
 
 — 3.7 
 
 — 6 
 
 —16.8 
 
 —21.1 
 
 87 
 
 24.4 
 
 30.5 
 
 65.4 
 
 10.4 
 
 13 
 
 25 
 
 —3.1 
 
 — 3.8 
 
 — 6.2 
 
 —17 
 
 —21.2 
 
 86 
 
 24 
 
 30 
 
 66 
 
 10.2 
 
 12.7 
 
 24.8 
 
 —3.2 
 
 — 4 
 
 — 7 
 
 — 17.3 
 
 -21.6 
 
 85 
 
 23.5 
 
 29.4 
 
 64.5 
 
 10 
 
 12.5 
 
 24 
 
 —3.6 
 
 — 4.4 
 
 — 7.6 
 
 —17.6 
 
 —22 
 
 84.2 
 
 23.2 
 
 29 
 
 54 
 
 9.7 
 
 12.2 
 
 23 
 
 —4 
 
 — 5 
 
 — 8 
 
 —17.7 
 
 —22.2 
 
 84 
 
 23.1 
 
 28.9 
 
 53.6 
 
 9.6 
 
 12 
 
 22 
 
 —4.4 
 
 — 6.5 
 
 — 8.5 
 
 —18 
 
 —22.5 
 
 83.7 
 
 23 
 
 28.7 
 
 63 
 
 9.3 
 
 11.6 
 
 21.2 
 
 —4.8 
 
 — 6 
 
 — 9 
 
 —18.2 
 
 —22.7 
 
 83 
 
 22.6 
 
 28.3 
 
 52.2 
 
 9 
 
 11.2 
 
 21 
 
 -4.9 
 
 — 6.1 
 
 — 9.4 
 
 —18.4 
 
 —23 
 
 82.4 
 
 22.4 
 
 28 
 
 52 
 
 8.9 
 
 11.1 
 
 20.7 
 
 —6 
 
 — 6.2 
 
 —10 
 
 —18.6 
 
 —23.3 
 
 82 
 
 22.2 
 
 27.7 
 
 51.8 
 
 8.8 
 
 11 
 
 20 
 
 —5.3 
 
 — 6.6 
 
 —10.7 
 
 —19 
 
 —23.7 
 
 81.5 
 
 22 
 
 27.5 
 
 51 
 
 8.4 
 
 10.5 
 
 19.4 
 
 —5.6 
 
 — 7 
 
 — 11 
 
 —19.1 
 
 —23.8 
 
 81 
 
 21.7 
 
 27.2 
 
 50 
 
 8 
 
 10 
 
 19 
 
 —5.7 
 
 — 7.2 
 
 —11.2 
 
 —19.2 
 
 —24 
 
 80.6 
 
 21.6 
 
 27 
 
 49 
 
 7.5 
 
 9.4 
 
 18.5 
 
 —6 
 
 — 7.5 
 
 —12 
 
 —19.6 
 
 —24.4 
 
 80 
 
 21.3 
 
 26.6 
 
 48.2 
 
 7.2 
 
 9 
 
 18 
 
 -6.2 
 
 — 7.7 
 
 —13 
 
 —20 
 
 —25 
 
 79.2 
 
 21 
 
 26.2 
 
 48 
 
 7.1 
 
 8.9 
 
 17.6 
 
 -6.4 
 
 — 8 
 
 — 14 
 
 —20.4 
 
 —25.6 
 
 79 
 
 20.9 
 
 26.1 
 
 47.7 
 
 7 
 
 8.7 
 
 17 
 
 —6.6 
 
 — 8.3 
 
 -14.8 
 
 —20.8 
 
 —26 
 
 78.8 
 
 20.8 
 
 26 
 
 47 
 
 6.6 
 
 8.3 
 
 16.2 
 
 —7 
 
 — 8.7 
 
 -15 
 
 —20.9 
 
 —26.1 
 
 78 
 
 20.4 
 
 25.5 
 
 46.4 
 
 6.4 
 
 8 
 
 16 
 
 -7.1 
 
 — 8.9 
 
 -15.2 
 
 —21 
 
 —26.2 
 
 77 
 
 20 
 
 25 
 
 46 
 
 6.2 
 
 7.7 
 
 15.8 
 
 —7.2 
 
 — 9 
 
 -16 
 
 —21.3 
 
 —26.6 
 
 76 
 
 19.5 
 
 24.4 
 
 45.6 
 
 6 
 
 7.6 
 
 15 
 
 -7.5 
 
 — 9.4 
 
 —16.6 
 
 —21.6 
 
 —27 
 
 75.2 
 
 19.2 
 
 24 
 
 45 
 
 5.7 
 
 7.2 
 
 14 
 
 —8 
 
 —10 
 
 —17 
 
 —21.7 
 
 —27.2 
 
 75 
 
 19.1 
 
 23.8 
 
 44.6 
 
 6.6 
 
 7 
 
 13 
 
 —8.4 
 
 —10.5 
 
 —17.5 
 
 —22 
 
 —27.5 
 
 74.7 
 
 19 
 
 23.7 
 
 44 
 
 5.3 
 
 6.6 
 
 12.2 
 
 —8.8 
 
 —11 
 
 —18 
 
 —22.2 
 
 —27.7 
 
 74 
 
 18.6 
 
 23.3 
 
 43.2 
 
 6 
 
 6.2 
 
 12 
 
 —8.9 
 
 —11.1 
 
 -18.4 
 
 —22.4 
 
 —28 
 
SOURCES AND MANAGEMENT OF HEAT. 
 
 149 
 
 c 
 
 a c 
 
 H 
 
 L 
 
 »•: 
 
 •^4 
 
 
 a ^ 
 
 ■^4 
 
 L 
 
 h ti 
 
 ■^4 
 
 U 
 
 |i 
 
 c S 
 
 P 
 
 |i 
 
 1^ 
 
 P 
 
 |i 
 
 1^ 
 
 P 
 
 a 3 
 
 c 2 
 6^ 
 
 —19 
 
 —22.6 
 
 —28.3 
 
 —25 
 
 —25.3—31.6 
 
 —30 
 
 —27.5 
 
 —34.4 
 
 —35.5 
 
 —30 
 
 —37.5 
 
 —19.7 
 
 —23 
 
 —28.7 
 
 —25.6 
 
 —25.6—32 
 
 —31 
 
 —28 
 
 —35 
 
 —36 
 
 —30.2 
 
 —37.7 
 
 —20 
 
 —23.1 
 
 —28.9 
 
 —26 
 
 —25.7 —32.2 
 
 —32 
 
 —28.4 
 
 —35.5 
 
 —36.4 
 
 —30.4 
 
 —38 
 
 —20.2 
 
 —23.2 
 
 —29 
 
 —26.5 
 
 —26 —32.5 
 
 —32.8 
 
 —28.8 
 
 —36 
 
 —37 
 
 —30.6 
 
 —38.3 
 
 —21 
 
 —23.5 
 
 —29.4 
 
 —27 
 
 —26.2 —32.7 
 
 —33 
 
 —28.9 
 
 —36.1 
 
 —37.7 
 
 —31 
 
 —38.7 
 
 —22 
 
 —24 
 
 —30 
 
 —27.4 
 
 —26.41-33 1 
 
 —33.2 
 
 —29 
 
 —36.2 
 
 —38 
 
 —31.1 
 
 —38.9 
 
 —23 
 
 —24.4 
 
 —30.5 
 
 —28 
 
 —26.61—33.3 
 
 —34 
 
 —29.3 
 
 —36.6 
 
 —38.2 
 
 —31.2 
 
 —39 
 
 —23.8 
 
 -24.8 
 
 —31 
 
 -28.7 
 
 —27 
 
 —33.7 
 
 —34.6 
 
 —29.6 
 
 —37 
 
 —39 
 
 —31.5 
 
 —39.4 
 
 —24 
 
 —24.9 
 
 —31.1 
 
 —29 
 
 —27.1 
 
 —33.8 
 
 —35 
 
 —29.7 
 
 —37.2 
 
 —40 
 
 —32 
 
 —40 
 
 —24.2 
 
 —25 
 
 —31.2 
 
 —29.2 
 
 —27.2 
 
 —34 
 
 
 
 
 
 
 
 CHAPTER XI 
 
 SOURCES AND MANAGEMENT OF HEAT. 
 
 Heat plays an important part in changing the state and 
 properties of bodies, and we, therefore, devote a chapter to 
 the various modes of applying that agent in chemical opera- 
 tions. The processes dependent upon its action are, princi- 
 pally. Fusion, Ignition, Calcination, Incineration, Roast- 
 ing, Deflagration, Reduction, Cupellation, Sublimation, 
 Distillation, Digestion, Decoction, Boiling, Solution, 
 Evaporation, Crystallization, and Desiccation. 
 
 Furnaces. — Laboratory furnaces differ in construction ac- 
 cording to the uses for which they are designed. The main 
 parts of every furnace are the body in which the heat is pro- 
 duced, the grate or bars upon which the fuel rests, the ash 
 pan for receiving the residue, and smoke pipe for conducting 
 off the gaseous products of combustion. 
 
 The stationary furnace, Fig. 6, answers very well for ge- 
 neral purposes, but is less convenient in a small laboratory 
 than a portable furnace. When the former is not possessed 
 by the chemist, the sand bath may be constructed as directed 
 at p. 56, or in default of gas as a heating medium, the top 
 of the stove (p. 39) may serve as a substitute. Such an ar- 
 rangement is cleanly and economical, and does away with the 
 
150 
 
 SOURCES OF HEAT — FURNACES. 
 
 Fig. 87. 
 
 necessity of cumbersome brick work. It has also the advan- 
 tage of being ready at all times for use, and is all-sufficient 
 for the purposes of analysis in a private experimental labora- 
 tory. 
 
 It is useless to multiply furnaces in a small laboratory, for 
 they occupy room which may be wanting 
 for other purposes, and therefore, a selec- 
 tion should be made of one which in its 
 arrangement is applicable to all the ne- 
 cessities of the chemist. Of this kind, 
 Luhme's and Kent's are the best. One of 
 either, with a small charcoal furnace. Fig. 
 87, such as may be bought at any crockery 
 shop, for table use, will constitute the whole 
 stock required of this sort of apparatus. 
 Luhme's furnace. — Figs. 88, 89 exhibit this furnace, the 
 cylindrical form of which is to be preferred on account of its 
 producing a higher heat with less fuel than any other. It 
 is of strong plate-iron, and lined in the body and dome 
 with refractory fire clay. Its dimensions are twenty-four 
 
 inches in height, and nine inches in diameter. The body, 
 a, 6, c, d, is capped with a ring of the same circumference as 
 the clay cylinder beneath. The doors are shown at g and h. 
 The circular openings, x, x, opposite to each other, are for the 
 passage of tubes, and when out of use can be closed by the 
 plugs accompanying the furnace for that purpose. The inte- 
 rior of the furnace, as seen from above, is shown by Fig. 90. 
 The knobs e, e, e, projecting inwardly, serve as supports for 
 vessels which are smaller than the mouth of the furnace, 
 
luhme's universal furnace. 
 
 151 
 
 whilst the iron juts, d d d, directed outwardly, are rests for 
 the larger, this arrangement being necessary in both instances, 
 to the perfection of the draught. The iron jacket, Fig. 91, 
 
 Fig. 90. 
 
 Fig. 91. 
 
 adapted to the opening, a c?. Fig. 88, forms a support for the 
 double sand bath. Fig. 92, for retorts, and other glass vessels. 
 The slope on the side of the sand bath is for the exit of the 
 neck of the retort; and the circular openings, k k k k, Fig. 
 93, are fitted with covers, by which to augment or decrease 
 the draught, as may be required. 
 
 A supplementary sand bath. Fig. 94, is made with a broad 
 extent of surface for digestions, evaporations, &c. 
 
 Fig. 93. 
 
 Fig. 94. 
 
 The dome, Fig. 95, confers the power of a wind furnace 
 when high heat is required. As this chimney becomes too hot 
 to be handled, it is removed when heated with suitable tongs, 
 the form of which is shown in Fig. 96. 
 
 The relative position of the several parts of this furnace, 
 we give in the annexed drawing. Fig. 97. 
 
 Kent's universal furnace, which is an improvement upon the 
 above, is shown by Fig. 98 in front and side views at A and B. 
 The body is fourteen inches high, by seven inches in diameter, 
 
 « 
 
152 
 
 KENT S UNIVERSAL FURNACE. 
 
 and in material and general construction is similar to Luhme's 
 furnace. There are six doors: — one at the base for the ad- 
 mission of air, another in the middle for the entrance of the 
 fuel and for the reception of the muffle used in cupellation. 
 The door in the dome is for the purpose of feeding the fire in 
 crucible operations; and that in the side, at the top, for the 
 reception of the neck of a retort, or of the sand bath c, Fig. 
 98. The two lateral openings, opposite to each other, are for 
 the passage of tubes, or of an iron bar as a support to the 
 rear end of the muffle. 
 
 Fig. 95. 
 
 Fig. 96. 
 
 The two sand baths for distillation and evaporation are 
 seen at c and D, Fig. 98. 
 
 The plugs E are for closing the two circular openings bj 
 which it is coupled with the pipes connecting it with the labo- 
 ratory flue. In crucible operations, the smoke-pipe should 
 lead from the top opening, and in evaporations, from the aper- 
 ture in the back. The openings in the flue must be above the 
 level of the furnace. 
 
EVAPORATINO AND REVERBERATORY FURNACES. 153 
 
 Fig. 98. 
 
 The remaining opening at the base is for the introduction of 
 the mouth of a bellows, by which it may be converted into a 
 blast furnace. 
 
 As our advice is to select a single furnace, combining in its 
 construction the power and convenience of the several differ- 
 ent kinds required in the laboratory, we proceed to make 
 known how Luhme's or Kent's apparatus may be adapted to 
 the various purposes of the chemist. 
 
 1. As an evaporating and calcining furnace, — As very 
 high heat is seldom required for evaporations, the body of the 
 furnace alone answers every purpose. For small operations, 
 or when but a small fire is required, its capacity may be di- 
 minished by inserting an inner cylinder of baked clay. To 
 increase the draught, all the doors should be closed, and to 
 augment still further the heat, as is necessary in the calcina- 
 tion of certain substances, the dome and chimney may be 
 used. In this latter case, by means of the door in the mid- 
 dle, the progress of the operation may be examined without 
 removing the chimney dome, or cooling the interior of the 
 furnace. 
 
 The sand and other baths, which have their places upon the 
 top of this furnace, serve for digestions, evaporations, &c., in 
 vessels which require the abatement and equalization of the 
 heat by intermedia. 
 
 2. As a reverberator^ furnace. — This kind of furnace is 
 adapted to operations demanding a high temperature, as in 
 the heating of crucibles, tubes, &c., and also in sublimation 
 
 11 
 
154 WIND AND BLAST FURNACES. 
 
 and similar processes requiring the application of a steady heat 
 to all portions of the vessel, rather than a very great heat to 
 any one part of it. 
 
 Luhme's or Kent's furnace is rendered reverberatory by the 
 use of the dome, which allows the vessel to be entirely sur- 
 rounded by flame, and reflects back the heat upon and around 
 its whole surface, and thus by equalizing the temperature, pre- 
 vents the condensation of vapors in the upper parts, an im- 
 portant object in distilling from beaked vessels. 
 
 Coke or charcoal is the fuel generally used, the latter being 
 preferable for a furnace of small dimensions ; and the draught 
 may be increased by lengthening the chimney. 
 
 The crucible, or vessel, must be placed in the centre, sup- 
 ported upon half of a fire-brick, in such a situation that the 
 cold air ascending through the grate may not prevent the 
 heating of its bottom. The fire is then kindled and main- 
 tained by fresh supplies of fuel, which are added carefully so 
 that they may not, whilst cold, come in contact with the hot 
 vessel and occasion its fracture. 
 
 3. As a wind furnace. — Wind furnaces are used for the 
 vitrification of mixtures, reduction and fusion of metals, and for 
 other operations requiring a prolonged elevation of tempera- 
 ture. 
 
 The combustion is urged by the draught of a flue, and the 
 degree of heat within the furnace depends upon the size and 
 height of the chimney into which this flue passes. The in- 
 tensity of the heat is increased by so proportioning the dimen- 
 sions of the furnace and the chimney that their diameters are 
 equal, and the height of the latter twenty to thirty times the 
 diameter of the former. 
 
 Luhme's or Kent's furnace may be converted into a wind 
 furnace by putting on the dome, closing all the openings, and 
 giving a free access of air to the grating through a pipe at- 
 tached to the circular nozzle in the hearth space, and leading 
 into one of the flues of the laboratory chimney. The smoke- 
 pipe may lead into the same flue, and both should be fitted 
 with dampers for the regulation of the draught. 
 
 4. As a blast furnace. — Blast furnaces are serviceable for 
 expeditiously producing a great intensity of heat, and are 
 used for fusions and other operations which require more 
 power than that of the wind furnace. 
 
 The combustion is urged by a current of air forced through 
 
THE ASSAY OR CUPEL FURNACE. 155 
 
 a pair of double bellows, the nozzle of which leads into the 
 circular opening near the base of either of the aforenamed 
 furnaces. The connection should be tightly adjusted with 
 LUTE, so as to prevent any escape of air. The arrangement 
 otherwise is exactly the same as for the wind furnace. 
 
 In blowing the blast, let the stream of air entering the fur- 
 nace be small at first, and be gradually increased as the tem- 
 perature becomes higher. The maximum heat can be hasten- 
 ed by weighting down the bellows, and thus augmenting the 
 force of the blast. 
 
 Sefstrom's {Berzelius, vol. 8), and Aikin's (Faraday^ p. 95), 
 blast furnaces are said to give heat sufficient to melt felspar. 
 
 The blast may be furnished to the preceding furnaces from 
 the pneumatic table. Fig. 30, through a flexible leaden pipe, 
 connected at either end by means of coupling screws. As 
 the lead pipe might be softened by a too great proximity to 
 the heated furnace, the opening in the ash pit of the latter 
 to which the former is to be attached, should be fitted with 
 about two feet of iron gas pipe so as to prevent direct con- 
 tact. 
 
 5. As an assay or cupel furnace. — The same arrangement 
 which is directed for a reverberatory 
 will convert Luhme's or Kent's into a Fig. 99. 
 
 cupel furnace; the only additional re- ^ — 
 
 quisite being a muffle, Fig. 99, for the /^ 
 reception of the cupels in assaying / _ 
 operations. ^^^ '^^ 
 
 A very convenient and effective fur- 
 nace for CUPELLATION, is shown in views by Figs. 100, 101. 
 
 It is made of refractory fire clay, and hooped with strong 
 iron bands fastened together by screws in order that it may 
 better withstand the high temperature to which it is subjected. 
 
 A, A^, is the ash-pan, of diameter sufficient for the reception 
 of the body of the furnace b b'. The door, c, is for the exit 
 of the cinders, and the ingress of the air. The larger open- 
 ing, d', in the body of the furnace, is for the introduction of 
 the muffle, and a corresponding one, D, opposite, for a prism- 
 shaped support of baked clay for maintaining the muffle in a 
 horizontal position. The mouth-piece, supported by a small 
 platform, affords the facility of admitting or preventing the 
 access of air to the interior of the muffle. 
 
 There are other openings throughout the circumference of 
 
156 
 
 LIEBIG S FURNACE. 
 
 the body immediately above the grate, for increasing the 
 draught when necessary. 
 
 Fig. 100. 
 
 Fig. 101. 
 
 In the part of the dome e is a door for the introduction 
 of the fuel. The two openings e e are for the introduction of 
 a poker to arrange the fire. 
 
 At the top of the furnace is a dome G G, to which is adapt- 
 ed a sheet iron pipe for increasing the draught. 
 
 A sliding door H and a small circular gallery i ^, as a sup- 
 port for heated coals, afford additional means of increasing 
 the draught. 
 
 Furnaces of this kind may be had at the pottery of Haig 
 & Co., or of A. Miller, of this city, reference being given to 
 the form and directions in this book. 
 
 Liehigs furnace. — This is a small sheet iron furnace with 
 movable partitions and screen, in which the combustion of or- 
 
MANAGEMENT OF FURNACES. 
 
 157 
 
 Fig. 102 shows its 
 
 Fig. 102. 
 
 ganic bodies is effected by a charcoal fire, 
 interior. Fig. 103 gives a side 
 view of the furnace containing 
 a combustion tube under pro- 
 cess connected with organic 
 analysis. It is twenty-four 
 inches in length, three inches 
 in height, and three inches in 
 width at the bottom, diverging to four inches at the top. 
 
 Fig. 103. 
 
 Fig. 104. Fig. 105. 
 
 The combustion tube a passes through a circular opening in 
 the closed end of the furnace and rests upon sheet iron sup- 
 ports. Fig. 104. The grate consists of a 
 series of slits in the bottom of the fur- 
 nace which are distant from each other 
 about half an inch. The sheet iron 
 screens, Fig. 105, are used to confine the 
 fire to certain parts of the tube. 
 
 The furnace is used upon the table, 
 and should rest upon a stone of length nearly equal to its own. 
 
 Management of furnaces. — All furnace operations should 
 be conducted under the stationary hood, Fig. 9, so that the 
 carbonic acid and other noxious exhalations may have an 
 escape from the laboratory, and the sparks and heated air 
 emitted, be prevented from endangering the comfort and 
 safety of the apartment. 
 
 If the furnace is without feet, it should rest upon a stone 
 block, and never directly upon the floor or the top of the 
 table, for its heated bottom may occasion a conflagration. 
 
 Coal, coke and charcoal are the fuel most used. Coal is 
 the least available, for it contains sulphur, and yields a large 
 amount of ash and clinker, which choke the grating, and it 
 should never, therefore, be used in the blast furnace. 
 
 Coke and charcoal, separately or combined, are used for 
 all the furnace operations, the former being preferable for 
 
158 
 
 THE FURNITURE OF FURNACES. 
 
 Fig. 106. 
 
 Fig. 107. 
 
 assays at a high temperature. Weight for weight, their 
 amount of heat is nearly equal, but the greater density of the 
 coke enables it to give more bulk for bulk by ten per cent. 
 Charcoal ignites most readily, but coke is more durable. 
 Moreover, when of good quality and free from sulphurous and 
 earthy matter, it gives but little ash or clinker. By mixing 
 the two together we obtain the good qualities of both; but 
 charcoal alone is preferable for heating glass and porcelain 
 vessels. Before using the coke or charcoal, care must be taken 
 that it has been freed from dust and dirt by sieving, and that 
 the pieces are about the size of a walnut, so that they may 
 pack away neither too loosely nor too compactly. 
 
 All of the fuel should be kept in a dry place, for the vapor 
 arising from wet coal and condensing upon the surface of fra- 
 gile vessels which are being heated, will be apt to cause their 
 fracture. 
 
 The crucibles should be placed in the centre of the furnace, 
 upon a support which may be a 
 piece of fire-brick or a cast-iron 
 trivet, as shown by Fig. 106. This 
 support answers also for stone-ware 
 retorts; but a preferable form for 
 this purpose is the crow's-foot. Fig. 
 107. The size of these latter imple- 
 ments is regulated by the proportions of the vessels which 
 they support. 
 
 For supporting basins and flasks over the evaporating fur- 
 nace, an iron trellis of strong wire. Fig. 
 108 is necessary. A series of these iron 
 trellises, of different sized meshes, will 
 be found convenient for adapting the 
 heat to glass vessels, tubes, &c. 
 
 In placing the vessels in the fire or 
 in the sand bath, they must be made 
 to stand firmly, and as near to the 
 centre as possible, so that they may 
 be equally heated all around. To pre- 
 vent damage to them by a too sudden 
 rise of temperature, the fire must be 
 urged gradually, and when the operations are finished, they 
 should be left to cool with the furnace, or, if taken out, be 
 transferred to a cool sand bath, so that their refrigeration 
 may not be so sudden as to cause fracture. 
 
 Fig. 108. 
 
THE FURNITURE OF FURNACES. 
 
 159 
 
 When the vessel, to be heated over the naked fire, is of less 
 diameter than the mouth of the furnace, this latter may be 
 proportionally lessened by means of a suitably adapted flat 
 iron ring. These rings Figs. 109, 110, are also useful when it is 
 
 Fig. 109. 
 
 Fig. 110. 
 
 required to concentrate the heat of the furnace in the centre 
 of the vessel, and therefore it is advisable to have a series 
 of them, the centre openings of which should decrease gradu- 
 ally so as to render them convenient for all ^ized vessels. 
 
 Before commencing operations the furnace must be entirely 
 freed from ashes and 
 
 clinker, and the coal Fig. ill. 
 
 placed around the 
 vessel in layers. — 
 When a fresh supply 
 of fuel is requisite, 
 it may be added 
 through the doorway 
 made for the purpose. 
 The auxiliary appa- 
 ratus of a furnace, 
 other than that al- 
 ready mentioned, are 
 an ordinary iron po- 
 ker for clearing the 
 grate; a pair of tongs bent at right angles. Fig. Ill, for plac- 
 ing the crucibles in the fire, and another pair curved at their 
 ends for grasping the crucibles around the body and remov- 
 ing them from the furnace, if necessary, whilst still hot. 
 Another pair of common fire tongs, Fig. 113, is convenient 
 for adding the lumps of coal. 
 
 Fig. 113. 
 
 Fig. 112. 
 
160 LAMPS. 
 
 Lamps. — Lamps are convenient and economical substitutes 
 for furnaces in table operations. Being less cumbersome and 
 more cleanly than the latter, they are readily manageable and 
 always ready for use ; and they also afford the means of more 
 rapidly multiplying results. 
 
 The amount of heat to be obtained by these instruments 
 depends upon their size and arrangement. A properly con- 
 structed lamp may be made subservient to all the require- 
 ments of the nicer heating operations of the laboratory, from 
 gentle digestion or evaporation to those processes which re- 
 quire a very high degree of heat. 
 
 The heating power of the flame is most active immediately 
 beneath its summit, and the vessel should be gradually brought 
 into direct contact with that portion. The vessel should be 
 heated more gradually in proportion to the thickness. When 
 thick glass or porcelain or other fragile bad conducting ma- 
 terial is suddenly heated, the heated part expands while the 
 rest does not, and this unequal tension of two adjacent parts 
 causes the cracking or fracture of the vessel. There is, there- 
 fore, a great advantage in employing glass or porcelain ves- 
 sels of thin structure, for the heat being rapidly conducted 
 through them, the liability of fracture is diminished. As 
 strength is, however, often required and thicker vessels must 
 be used, the above principles of expansion and conduction 
 must be remembered when they are employed. 
 
 In order to apply a small fire to a large surface, the heat 
 may be diffused by setting the vessel in a sand or water- 
 bath, or, which is convenient and more cleanly, a plate of 
 sheet metal or wire gauze may be placed between the vessel 
 and the fire. It is safer not to allow the vessel to touch the 
 plate or gauze. Iron or brass gauze may be used, although 
 fine copper gauze is preferable, because more durable. 
 
 The combustible or fuel most commonly used in chemical 
 lamps is alcohol, though pyroxylic spirit and lamp oil are 
 occasionally employed. 
 
 Alcohol flame gives no smoke or unpleasant odor, the pro- 
 duct of combustion being only carbonic acid and water ; while 
 lamp oil, especially where the supply of oil to the wick is 
 insufficient, produces a black carbonaceous deposit upon the 
 bottom of the vessel which occasions a loss of heat by radia- 
 tion. 
 
 The alcohol flame moreover does not have the same inju- 
 
161 
 
 rious effect upon bodies in contact with it as the oil flame with 
 its sooty deposit; nor does it hide from view the contents of 
 test-tubes, retorts and other vessels by blackening the glass. 
 
 A strong heat may be obtained from alcohol, but in tedious 
 processes, which require a long-continued uniformity of tem- 
 perature, the best lamp oil, or better^ olive oil may be used in 
 an Argand burner. 
 
 Pyroxylic spirit is less objectionable than lamp oil, and 
 more so than alcohol. The many advantages of the latter, 
 therefore, give it the preference over all other combustibles as 
 fuel for chemical lamps. It should be of about the sp. gr. of 
 0.85. Lamps burning, should always be extinguished before 
 having the supply of fuel renewed, so as to prevent liability 
 of explosion. The spirit is then gradually introduced from the 
 tubed bottle. Fig. 38, p. 72, until the reservoir is nearly full. 
 This mode prevents its running out and diminishes the risk 
 of overflow from too large a stream. When the lamp is not in 
 use, the wick should always be covered with the extinguisher 
 to prevent loss by evaporation. 
 
 The tongs accompanying these lamps are a pair Fig. 1 14. 
 of surgeons' forceps of such a form as shown by Fig. 
 114. As they are liable to become oxidized by con- 
 stant exposure, it is better to have their prongs 
 plated with silver. This precaution lessens the 
 liability of debasing the contents of crucibles with 
 iron oxide which may become detached when they 
 are handled with rusty tongues. 
 
 We proceed to speak of such lamps as are suit- 
 able to laboratory purposes. 
 
 Glass, Spirit Lamp. — This is a small glass lamp like the 
 one shown in Fig. 115. The body 
 is the reservoir for the alcohol. To Fig. 115. 
 
 the neck b is adjusted a copper circu- 
 lar shield c, with a tube in its centre 
 
 H for the passage of the wick, which 
 
 K should be of cotton, and similar to 
 
 H| that used for tallow candles. The 
 
 Hl shield should rest upon, rather than 
 
 ^B within the neck, otherwise its expan- 
 
 ^B sion by the heat may cause the break- 
 
 ^H age of the glass. A minute opening 
 
 ^B drilled in the shield is also requisite for the escape of vapor 
 
 I 
 
162 
 
 HEATING OF TUBES BY LAMPS. 
 
 in case the alcoliol should become heated. The glass cap a, 
 ground interiorly, so as to fit hermetically to the neck of the 
 lamp when not in use, prevents the evaporation of the alcohol 
 and the consequent impregnation of the wick with water, which 
 renders its relighting difficult. The lamp must, however, be 
 invariably extinguished before putting on the cap. 
 
 Fig. 116. 
 
 Fig. 1 17. 
 
 These lamps are useful for heating small apparatus, such 
 as test tubes. Figs. 116, 117, and reduction tubes, Fig. 148, 
 and for larger vessels which require only a gentle heat, as 
 
 shown in Fig. 118. 
 
 Fig. 118. 
 
BERZELIUS* SPIRIT LAMP. 163 
 
 Berzelius Lamp. Fig. 26 at page 54 represents this lamp 
 with the improvements recommended by Mitscherlich and Lie- 
 
 big. It should be made of thick sheet copper or brass, and brazed 
 instead of being soldered together. Its form is that of an Ar- 
 gand lamp, with a circular body or reservoir g^ which receives 
 its fuel through the stoppered opening r. The mechanism 
 contained in the frame work s, and communicating with the 
 cylinder t allows the elevation or depression of the wick at 
 will. The only communication between this portion of the 
 lamp and the reservoir is by a small tube through which the 
 alcohol is supplied to the wick. The chimney u may be 
 movable and adapted to a flattened socket soldered to the side 
 of the inner circumference of the reservoir, or else be hinged 
 in the same position so that it may be thrown back when the 
 lamp is to be lighted or trimmed. Surmounting the chimney 
 is a crucible jacket h with a handle q adapted to the socket or 
 thumb screw. The crucible with its movable cover d, Fig. 120, is 
 
164 CRUCIBLE JACKET. — LAMP SUPPORT. 
 
 placed in the centre of the sheet iron jacket upon supports 
 so as to receive the full force of the 
 Fig. 120. flame. It is designed to protect the 
 
 crucible from all air save that which 
 passes up the chimney. The whole 
 arrangement is shown by Fig. 120, C 
 / r\ \ being the chimney of the spirit lamp, 
 
 Y rr""^l '>\ \ and the arrows showing the direction 
 
 IB I ^ \^ \ (jf i]^Q flame which passes unobstruct- 
 
 ed upward. All atmospheric air save 
 that which passes up the chimney 
 being excluded, the heating power of 
 the lamp is greatly increased. 
 
 The lamp, as is seen by the figures, 
 is mounted upon a fork v, which slides 
 upon the upright of the support h. 
 This upright is a smooth wrought iron or brass rod, screw cut at 
 its lower end, and firmly fastened to the walnut foot b by means 
 of a nut. The foot serves as a ballast and at the same time 
 as a bed for a large capsule, which is a convenient receptacle 
 for any matter which may be accidentally spilled from the 
 heating vessel. The pan p is intended for the same purpose 
 when the support is occupied on either side. There are other 
 appliances which add to the convenience of this lamp. They 
 consist of thumb screws and sockets d effor holding the iron 
 wire rings ml i k. These rings, varying in diameter, serve 
 as supports for the vessels employed, and to steady those 
 which are tall like the flask shown in the figure, a clamp 
 / is requisite. The thumb screw to which the rings are 
 attached slide upon the upright rod and allow the elevation 
 or depression of the heating vessel at will. The iron plate 
 sand bath n is very useful for digestions in beaker glasses 
 which will not safely bear direct contact with the flame. 
 
 The fittings of this and all other chemical lamps should 
 combine lightness with strength so as to avoid the dissipa- 
 tion of too much heat by excess of metal. 
 
 Fig. 121 exhibits a lamp support not very dissimilar to the 
 preceding, but with a cast iron triangular foot 5, of weight suf- 
 ficient to prevent the lamp from being upset by the super- 
 position of heavy vessels. The iron triangle c? is a very 
 convenient substitute for the ring when a crucible is to be 
 heated, as that shape aff'ords a better support. The rod a of 
 
LUHME S LAMP. 
 
 165 
 
 Fig. 121. 
 
 brass or iron is from twenty to twenty-four inches in length. 
 The fork g for the lamp, and the rings, are all adapted to the 
 thumb screws which hold them steadily 
 until they are to be replaced by others 
 of different form or size for different and 
 larger vessels. 
 
 A very convenient modification of Ber- 
 zelius' lamp for boiling in large vessels is 
 shown by Fig. 122. It is supported by 
 three feet of solid brass. Adjusted to its 
 wooden handle is a brass crook for support- 
 ing the necks of beaked vessels, retorts, and 
 the like. This crook can be lowered or 
 elevated at will by means of the thumb 
 screw by which it is fastened. Two rings 
 accompany it, one of open work for the 
 support of capsules, broad and round bot- 
 tomed vessels ; and the other cullendered 
 with fine holes for the distribution of the 
 heat to flat bottomed glass vessels. 
 
 This is a powerful lamp, and is more convenient for large 
 vessels than the lamp mounted as before described. Luhme, 
 
 Fig. 122. 
 
 
 who first recommended this form, also advises that there be 
 no direct communication between the reservoir and the circu- 
 
166 
 
 ROSE S LAMP. — HORSFORD S LAMP. 
 
 lar space containing the wick, because such an arrangement 
 is promotive of accidents. When the lamp has burned for a 
 length of time and nearly all the alcohol is consumed, the 
 reservoir becomes filled with vaporized spirit, which may ex- 
 plode when it is re-lit after being refilled. All this is pre- 
 vented by forming the connection by means of a tube. The 
 Berzelius lamps of recent manufacture are made with this 
 improvement. 
 
 Either of these lamps, and all others in which spirit is con- 
 sumed, must be provided with a metallic extinguisher to pro- 
 tect the wick and prevent evaporation of the alcohol. This 
 extinguisher is seen in Fig. 26. 
 
 Rose 8 Lamp. — This lamp, also constructed upon the prin- 
 ciple of the Argand burner, gives an intense heat. It pos- 
 
 Fig. 123. 
 
 sesses the advantage recommended 
 
 by Luhme of having the reservoir 
 at a distance from the burner, so 
 that the spirit remains unheated 
 during the longest operations. The 
 wick is regulated by a rack and 
 pinion as in the Berzelius lamps, 
 and its mode of management is pre- 
 cisely the same. Mr. Kent, of New 
 York, who manufactures them, an- 
 nexes the improvement of Prof. 
 Horsford, by which a heat is pro- 
 duced sufficiently intense for bend- 
 ing glass or fusing carbonate of 
 soda in a few minutes. The cop- 
 per reservoir is used by being placed 
 upon a tripod accompanying it, and 
 fitting to the Rose lamp as shown 
 by Fig. 124. Three fluid ounces of alcohol are poured therein, 
 and the screw plug tightly closed. The jet is cleaned by 
 probing it with a needle, and the heat of the lamp is applied 
 until the alcohol boils. The vaporized spirit passes through 
 the jet, and when the chimney is on, takes fire, and produces 
 a blast flame of great power. The contents of a platinum 
 crucible placed about half an inch above the chimney, as 
 shown in the figure, becomes fused in a few minutes. 
 
 The Russian Lamp. — This apparatus. Fig. 125, of Russian 
 invention, and similar in principle to Horsford's " Cambridge 
 
THE RUSSIAN LAMP. 
 
 167 
 
 Fig. 124. 
 
 blast lamp," is said by Noad to 
 afford a very powerful heat in a 
 few minutes. It consists of a 
 strong double brass cylinder or box, 
 the interior arrangement of which 
 is shown by the dotted lines in the 
 cut. A piece of tube terminating 
 in a jet passes from the exterior to 
 the interior chamber, rising nearly 
 to the top of the former. The fuel 
 is supplied through the aperture 5, 
 closed with a cork, and not with a 
 brass cap. The lamp is known to 
 be fully charged when the spirit 
 begins to flow from the jet. The 
 inner chamber is then to be filled 
 with the same spirit to within half 
 an inch of the apex of the jet. 
 The ignited spirit in the inner 
 chamber heats that in the outer, 
 and causes it to boil, and the pres- 
 sure of the vapor forces the boiling 
 spirit through the jet in a powerful 
 stream, which of course becomes 
 immediately inflamed, and acts as 
 
 an energetic blast, producing heat enough to ignite a plati- 
 num crucible placed above it to whiteness. The triangle 
 which supports the crucible 
 must be of platinum, and Fig. 125. 
 
 the ringsupon which the tri- 
 angle rests of very stout iron 
 wire in order to resist the 
 fusing effect of the flame. 
 
 There are certain precau- 
 tions necessary in the use of 
 this lamp, to guard the opera- 
 tor against accidents. Before 
 introducing the alcohol, it is 
 proper to be assured that the 
 jet is free from impediment 
 by blowing through it. The 
 cork stopper h must be put in rather loosely, so that it may 
 
168 THE GAS LAMP. — TABLE BLOW-PIPE. 
 
 offer no resistance should a stoppage occur during the opera- 
 tion. For still greater safety, that part of the lamp should 
 be turned from towards the experimenter. 
 
 Pyroxylic spirit* is the fuel recommended; and it is said 
 that a lamp of this construction, 3J inches in height, and 3J 
 in diameter, will burn with a charge of four ounces of spirit 
 for thirty minutes, which is long enough for most fluxions 
 with carbonated alkali. 
 
 The G-as Lamp. — This arrangement. Fig. 27, which has 
 been fully described at p. 54, supersedes all other heating 
 apparatus for table operations. Crucibles, capsules, and re- 
 torts are alike readily heated by it, and even distillations on 
 a large scale may be successfully performed. To effect the 
 latter object, the upper half of a black lead or clay crucible 
 may be placed around the lamp, provided with an opening on 
 one side for the beak of a retort to pass out. The lower half 
 of the crucible, with its bottom broken off, is then inverted 
 over the whole, and the hole at the top loosely covered to 
 allow of the escape of the products of combustion. By this 
 arrangement, the heat of the flame reverberates through the 
 dome, and increases the effect to such a degree that several 
 pounds of mercury may be distilled at once from the red oxide. 
 
 The Table Blow Pipe. — This table, shown in Fig. 30, and 
 described at p. 59, may be used either with a Berzelius or 
 Rose lamp, or the Argand gas burner. Fig. 31. Gas,t when 
 
 • Pyroxylic spirit is a very inflammable alcoholic compound, obtained as one 
 of the products of the destructive distillation of wood. As found in commerce 
 it is impure. (See Ure and Turner.) 
 
 f As the use of alcohol for lamps and of fuel for furnaces, with the necessary 
 attendance upon the latter, involves a considerable expense, annually, even in 
 an experimental laboratory, it is not inappropriate to allude here to an economi- 
 cal means of replacing them with gas. 
 
 The material which may be used for this purpose is the refuse fat of the 
 kitchen, a gallon of which in its melted state will yield 100 cubic feet of oil 
 gas, sufficient to feed a bat wing burner for upwards of seventy hours. 
 
 Its greater density and amount of olefiant gas give it superiority over the 
 coal and rosin gas. Moreover, it would be difficult to adapt an apparatus to 
 the manufacture of small quantities from the latter materials. Fig. 126 exhibits 
 Kent's portable apparatus for the manufacture of gas from grease. It consists 
 of a wrought iron retort, thirteen inches high and six inches in diameter, with 
 a large opening at the top for the passage of lumps of coke with which it is to 
 be three-fourths filled. The coke is used to increase the extent of the heating 
 surface so as to facilitate and hasten the generation of the gas. 
 
 The retort is to be heated to low redness, but no higher, otherwise the gas 
 becomes decarbonized. The oil is supplied to the retort in a thin but constant 
 stream from the funnel, through a small hole in the key of the stop-cock. The 
 
MANUFACTURE OF ILLUMINATING GAS FROM GREASE. 169 
 
 furnished by public companies, is by far the most economical 
 source of heat, and withal is powerful, readily manageable, 
 and cleanly. For all the nicer ignitions, fluxions, and fusions 
 it does away with the necessity of a furnace, which is less 
 convenient, and requires tenfold the time for its action. In 
 five minutes, by the use of this implement, we can often satis- 
 factorily complete processes which with a furnace would re- 
 quire an hour. This saving of time and fatigue is an import- 
 ant consideration when the operations are to be multiplied or 
 rapidly repeated. It is applicable to all the purposes of igni- 
 tion, fusion, and fluxion of limited quantities of matter, and 
 by " driving the current of air obliquely and somewhat down- 
 ward through the Argand burner, the process of cupellation 
 may be accurately performed on three hundred grains of lead.'* 
 
 retort is connected by an iron tube with a copper reservoir immersed in cold 
 water, for the purpose of cooling the gas and collecting a portion of undecom- 
 posed oil which passes over. An additional receiver renders this apparatus 
 applicable to the purposes of illumination or heating. All the pipes and appli- 
 ances for either are furnished with the apparatus by the manufacturer, to order. 
 The retort requires to be occasionally cleansed, but at no other time has it to be 
 necessarily opened. 
 
 Fig. 126. 
 
 Large vulcanized India-rubber bags make excellent gasometers for small 
 quantities of gas, but for 100 cubic feet, it will be better to have a sheet iron 
 bell well payed over, internally and exteriorly, with plumbago paint. The cis- 
 tern for its reception can be sunk in the yard, and for the above quantity its 
 dimensions must be 6^ feet diameter and 4^ feet depth. 
 
 12 
 
170 
 
 CRUCIBLE HEATED OVER BLOW-PIPE FLAME. 
 
 When gas is used it is only necessary to bring the Argand 
 burner, Fig. 31, over the jet 3, Fig. 30, and to depress it 
 
 Fig. 127. 
 
 \ ^^J 1 
 
 so much that its orifice may extend a short way into the flame 
 for heating a vessel of small surface, and still further for ves- 
 sels of greater superficies. The gas being turned on and in- 
 flamed, the treadle is then worked with the foot, slowly at 
 first, until the current of air thus forced up through the tube 
 changes the white and quiet flame into one of a pale reddish 
 tint and ragged outline. If too much air be driven through, 
 the flame becomes bluish, and the heat becomes less intense. 
 
 When a lamp is used, it is necessary that it should have a 
 circular Argand burner, which is to be placed over the jet 3, 
 in such a position that the orifice of the latter projects through 
 the centre of the burner, just beyond the top of the wick. 
 The length of the flame being proportional to the elevation of 
 the wick, the latter must be adjusted accordingly by the screw 
 and rack before being ignited. The flame being of the proper 
 height, the treadle 4, Fig. 30, is to be worked at first slowly, 
 for the heat must be gradually applied, and then more rapidly 
 by increasing the motion of the foot until the blast produces 
 a buzzing sound, when the impulse is continued or moderated 
 as the case may require. 
 
 The crucible to be heated is placed upon a wire triangle, 
 
HARE S COMPOUND BLOW-PIPE. 
 
 171 
 
 resting upon a ring of an upright support, as shown in the 
 figure, and is placed over the flame, so that it may be sur- 
 rounded by the upper or hotter portion (blow-pipe). If the 
 flame is smoky, and deposits carbon upon the sides of the 
 crucible, the blast must be increased or the flame lowered. 
 
 The operation being finished, the covered crucible is left to 
 cool before being opened. 
 
 Oompound Blow-Pipe. — This apparatus, known as Hare's 
 oxyhydrogen blow-pipe, is used for the fusions of such refrac- 
 tory but fusible substances as resist the highest power of the 
 furnace. Its action is based upon the intense heat produced 
 by the ignition of combined oxygen and hydrogen gases. 
 
 Dr. Hare's form of apparatus, with which he fused twenty- 
 eight ounces of platinum in one mass, is given and fully treated 
 of in his Oompend, and also in the Encyclopedia of Chemistry; 
 but our remarks will refer to a more economical instrument 
 constructed upon the same principle. 
 
 Fig. 128 exhibits the instrument as made and sold by Kent. 
 
 Fig. 128. 
 
 It consists of two vulcanized India rubber bags or reservoirs, 
 of twenty gallons or greater capacity. These bags are very 
 flexible, strong, and portable; one of the above size, when 
 empty, occupying but a very limited space. They are filled, 
 the one with oxygen, and the other with hydrogen gas, 
 each being fitted with a connecting screw and stop-cock, by 
 
172 
 
 GENERATION OF OXYGEN GAS. 
 
 which they can be adjusted directly to the generating appa- 
 ratus, as shown by Fig. 129, or with a gasometer, when they 
 
 are to be charged. The communication between the bags and 
 the jet-pipe above the table is by means of the flexible India 
 rubber or lead tubes, coupled by gallows screws. Fig. above. 
 The jets are so divided within the pipe that the gases enter 
 at opposite ends, and consequently are not mixed until they 
 meet at the arm of the jet, which is so arranged that it can 
 be raised or lowered on an ordinary retort stand. By this 
 arrangement, which is a convenient modification of the old 
 double jet, a jet of oxygen passes through the centre of a cir- 
 cular flame of hydrogen, the mixture and consequent explo- 
 sion of gases being avoided. 
 
 The gradual efilux of the gas from the reservoirs is efifected 
 by superposed weights — a much more convenient mode than 
 that of hydrostatic pressure, which is requisite when metallic 
 reservoirs are used. 
 
 The two gases are very readily prepared. The whole ap- 
 paratus for oxygen is shown in Fig. 129. The retort, a thin 
 copper flask, is connected with a brass cap and neck by a gal- 
 lows screw. 
 
 Four ounces of good chlorate of potassa, and one ounce of 
 peroxide of manganese are mixed together and placed in the 
 retort, the cap screwed down, and the joints luted with pipe 
 clay. The heat of a Berzelius lamp, applied as shown in the 
 figure, drives over ten gallons of pure oxygen in fifteen 
 minutes. 
 
 The lamp may be removed as soon as the gas begins to be 
 
GENERATION OP HYDROGEN GAS. 
 
 173 
 
 generated and pass over freely, as suflBcient heat will be re- 
 tained for the completion of the operation. The caput mor- 
 tuum of chloride of potassium and oxide of manganese re- 
 maining in the retort can readily be removed by water. 
 
 Hydrogen can still more readily be obtained from a self- 
 regulating reservoir. Fig. 130 exhibits the apparatus as made 
 
 Fig. 130. 
 
 by Kent. The copper cylinder which he uses is replaced in 
 other similar instruments by glass. It consists of a japanned 
 copper cylinder, 9 inches high, and 6 inches diameter, with a 
 cover and bell attached. 
 
 Within the bell hangs a basket of copper wire, which is to 
 be filled with about } lb. of zinc, in lumps. The outer cylin- 
 der is to contain 6 lbs. of cold diluted sulphuric acid, made 
 with 1 part acid to 4 of water. 
 
 In the upper part of the bell is a division, forming a recep- 
 tacle for a strong solution of potash, 2 f.^ of which are put 
 into it through the opening in the top, which is then to be 
 tightly stopped. 
 
 The apparatus being adjusted, and the stop-cocks opened, 
 the dilute acid rises in contact with the zinc, and generates 
 hydrogen gas, which, being forced through the potassa solu- 
 tions, becomes washed previous to its exit from the stop-cock 
 into the bag. An hour suffices to generate twenty gallons of 
 gas ; and, when it is desired to arrest the operation, close the 
 stop-cock so as to produce an accumulation of gas in the bell, 
 and thus displace the acid. The action may be renewed at 
 any time by opening the cock. 
 
 Accompanying this apparatus, as shown by separate figures 
 in the cut, are two convenient addenda for other purposes ; 
 
174 
 
 SELF-REGULATING GAS RESERVOIR. 
 
 one a jet, with platina sponge and fixtures, for producing an 
 instantaneous light, and the other for bending glass tubes, &c. 
 Thej are both readily attached to the stop-cock by their screws. 
 In the first case, the gas is projected against the platina 
 sponge, and becoming immediately ignited, affords a ready 
 means of lighting a taper. The sponge, when not in use, 
 should be kept covered and dry. 
 
 The oxyhydrogen blow-pipe is put into operation by first 
 charging the bags with gases, placing on their weights, letting 
 on the hydrogen, igniting it, and passing a jet of oxygen 
 through the flame directed upon the substance under process. 
 This substance should rest upon charcoal or fire-brick, and 
 in a cavity drilled for the purpose so as to prevent its being 
 blown away by the force of the blast. For the same reason, 
 when the substance is in powder, it is necessary to moisten it 
 with water, and compress it in the cavity. The charcoal rest 
 is very conveniently supported upon one of the sliding rings 
 (Fig. 131), which allows the facility of bringing it near to the 
 orifice of the pipe where the combustion takes place. 
 
 When this apparatus is used for the purposes of illumina- 
 tion, as in the production of the Drummond light^ which is 
 produced by the action of its flame upon a cylinder of lime, 
 the nozzle of the blow-pipe must be pointed upwards, so that 
 the flame may have full play upon the incandescent earth. 
 
 Fig. 131. 
 
 Fig. 132. 
 
 mSM 
 
SUPPORTS. — TRIANGLES. 
 
 175 
 
 Supports. — In lamp, table furnace, and blow-pipe opera- 
 tions, vessels are maintained over the fire by supports, dif- 
 fering in material and construction with the uses for which 
 thej are destined. 
 
 A very simple and economical support is shown in Figs. 131 
 and 132, the only difference between the two being in the shape 
 of the foot, one being rectangular and the other round. It 
 consists of an upright iron rod, from 20 to 24 inches long, and 
 about J of an inch or more in diameter, screwed into a cast 
 iron foot, and fastened beneath by a nut. The three project- 
 ing rings, of iron wire, 2, 3, and 4 inches in diameter, are held 
 by thumb screws, which permit their elevation or depression at 
 will. 
 
 For the larger stands the thumb screw is of iron, and of 
 the form exhibited in Fig. 127 and Figs. 133, 135, h. It is made 
 
 Fig. 133. 
 
 with two holes, at right angles to each other, and screws, one 
 for the reception of the iron upright, and the other for the 
 handle of the ring, which can readily be detached and replaced 
 by another of different size. This form of screw and socket 
 prevents the necessity and expense of having the rings at- 
 tached to the screws. One of these screws will answer for a 
 series of rings, and the latter being of iron wire, the operator 
 can readily form them himself of any required shape. With 
 this arrangement, and a series of dif- 
 ferent sized rings, the support is con- 
 venient for all its purposes without 
 the expense of a socket for each ring. 
 When the rings are too large for the 
 vessels to be heated, their diameters 
 may be diminished by means of stiff 
 wire triangles. Fig. 134. They are 
 particularly useful for the support of 
 small crucibles, as is shown in Fig. 
 
 Fier. 134. 
 
1Y6 
 
 THE UNIVERSAL SUPPORT. 
 
 Fig. 135. 
 
 27, p. 54. There should be 
 a number of them of different 
 sizes. 
 
 Fig. 135 exhibits what is 
 called the '^universal support.'' 
 The foot is of cast iron, and 
 the toes twelve inches apart. 
 The upright rod is of iron, 36 
 inches long, and | in diame- 
 ter. It is substantially made 
 for the support of heavy cap- 
 sules, retorts, &c. The thumb 
 screw and socket h are of solid 
 brass or iron. A brass vice, 
 6 inches long, and IJ inches 
 wide, lined in its mouth with 
 buckskin, is shown at g. It is 
 fitted by the arm / to the hole 
 c, and serves for the support 
 of heavy retorts and other beaked vessels, as shown in the 
 figure. Three solid brass rings, of from 4 to 7 inches diame- 
 ter, accompany this stand, and are held in the socket d by the 
 thumb screw a. As the arm of each of these rings is adapted 
 to the socket, one may replace the other when it is desired to 
 change the size. 
 
 Wooden supports adapted for tube arrangements, made of 
 box wood or hickory and lined with cork or buckskin at the 
 parts intended for grasping, are also convenient and necessary 
 pieces of apparatus. They consist of foot rod and nut simi- 
 lar to the iron supports. Their other parts are a wooden 
 vice (Gay-Lussac's), Fig. 138, for supporting the necks of re- 
 
 Fig.! 36. 
 
 r\ 
 
 Fig. 138. 
 
 Fig. 137. 
 
 ^L 
 
"WOODEN SUPPORTS. — RETORT HOLDERS. 
 
 177 
 
 torts and other beaked vessels; Grahn's cylinder holder, Fig. 
 137, for experiments with gases; and a wooden ring. Fig. 136, 
 as a rest for inverted flasks. Fig. 139 exhibits an upright 
 retort clamp with a movable joint and wooden screw by which 
 it can be raised or lowered at pleasure. The stand or lower 
 portion is similar in construction to D E, Fig. 142. 
 
 Fig. 140 represents another support with two sliding arms, 
 the upper one of which is a filtering stand, and the lower a 
 tube or retort holder. The funnel supports of the upper arm 
 are adjusted thereto by means of wooden thumb screws, and 
 may be removed at pleasure. These are less convenient than 
 the single filter stand, Fig. 141, though they have the advan- 
 
 Fig. 139. 
 
 Fig. 140. 
 
 Fig. 141. 
 
 ^i>^=. 
 
 I 
 
 tage of allowing several simultaneous filtrations upon one 
 arm, and thus a single stand may do the service of three or 
 four according to the length of the arm. The uprights of 
 these supports should be screw cut at the lower end and 
 fastened to their pedestals by means of nuts, which retain 
 them in place more firmly than any other mode. 
 
 Another form of stand is that known as Berzelius' table 
 support. It is of hard wood and consists of a loaded foot D, 
 Fig. 142, supporting a flat disc A, which by means of its leg 
 and the thumb screw E can be raised or lowered to any desired 
 height. This is a very convenient rest for a small lamp or fur- 
 nace or for recipients in distillations when it is required to raise 
 either above the level of the operating table. When in this 
 or other cases the surface of the supported vessel is round, it 
 
178 
 
 TUBE AND BULB RESTS. 
 
 Fig. 142. 
 
 i^^m 
 
 1 
 
 i^^i 
 
 Fig. 143. 
 
 Fig. 144. 
 
 is safer to steady it upon a braided 
 straw ring, Fig. 143, interposed between 
 its bottom and the disc. 
 
 For supporting tubes and other ves- 
 sels horizontally, the disc may be re- 
 placed by the brass crook as shown in 
 figure 144 ; and for globular vessels and 
 flasks by the wooden tripod. Fig. 145. 
 Each of these pieces is adapted to the 
 stand D, and one may replace the other 
 when necessary, the screw allowing them 
 to be raised and steadily maintained at 
 the required height. The height of this 
 instrument when drawn out to its full 
 length is twenty inches. 
 
 As a support for large evaporating 
 
 vessels over furnaces, an iron tripod, Fig. 
 
 146, is very convenient. 
 
 The test tube stand or rack, which is 
 
 the only support that remains to be men- 
 
 tioned, has been alluded to before, p. 54, 
 
 Fig. 145. 
 
 Fig. 146. 
 
 Fig. 25. A smaller one for table use is shown in Fig. 147. 
 It consists of two narrow uprights, say ten inches high, of 
 thin poplar wood, which are braced together by three shelves. 
 These shelves are perforated throughout their length with 
 auger holes for the reception of the test tubes. The smaller 
 and shorter tubes occupy the upper range, the interval be- 
 
TEST BACK. — BATHS. 
 
 179 
 
 tween which and the middle shelf Fig. 147. 
 
 should be less by an inch than that 
 between it and the lower. 
 
 The manifold uses of the pre- 
 ceding instruments will be fur- 
 ther explained when treating of 
 manipulations to which they are 
 applicable. At present a familiar 
 idea may be obtained by reference 
 to Figs. 116, 118, 119, and to the 
 cut below in which several of them, as applied in operations, 
 are included. 
 
 Fig. 148. 
 
 P" 
 
 CHAPTER XII. 
 
 BATHS. 
 
 The preceding chapter relates to apparatus for the direct 
 application of fire; our present remarks will refer to the 
 means by which the heat is moderated and diflfused before 
 it is allowed to reach the substances under process. These 
 
180 CONSTRUCTION OF BATHS. 
 
 means consist of baths, which are called vapor, water, saline, 
 metallic, oil or sand, according to the nature of the interposed 
 bodies employed. 
 
 The object of an intermedium is to prevent a too rapid ap- 
 plication of heat, and to give greater uniformity of tempera- 
 ture. Inequality and too sudden application of heat being 
 thus provided against, the fracture of vessels and ejection of 
 their contents, and many inconveniences attending other modes 
 of applying heat are avoided. 
 
 Baths are very convenient for heating substances which 
 require a constant and somewhat permanent elevation of 
 temperature, and which might undergo decomposition over 
 the naked fire. The temperature to be obtained, is, however, 
 only limited, but by a proper management of the fire any 
 degree of heat up to the maximum amount which the inter- 
 medium is capable of receiving from the means employed, can 
 be obtained. 
 
 Baths consist of two vessels of difierent diameters, and 
 they may be either of metal, stoneware, or porcelain. The 
 outer jacket receives the intermediary body, and the inner 
 one the substance to be heated. As generally constructed, 
 baths are made with but one jacket, the aperture or mouth 
 being of diameter corresponding with that of the heating 
 vessel which is to be placed over it. This arrangement obviates 
 the necessity of an inner jacket and also of the transfer of 
 the substance which is being heated. 
 
 Baths are useful in operating upon organic and other bodies 
 easily alterable by heat. They are also convenient for deter- 
 mining the melting point of those substances which are fusible 
 at or below the degree of heat, which can be imparted to the 
 liquid or vapor of the bath: that temperature being made 
 known by immersing a thermometer at the commencement 
 of the fusion and noting the degree. 
 
 In the fluid baths the thermometer may be permanently 
 fixed by means of a perforated cork, closing a circular aper- 
 ture in the lid. Fig. 84 with the scale upon the stem exhibits 
 the most suitable form of the instrument for this purpose. 
 The difference in temperature between the bath and the heat- 
 ing substance, which is sometimes very considerable, especially 
 when porcelain or glass is used, may be diminished by keep- 
 ing the bath always covered. If the vessels have smooth 
 surfaces, the heat obtained previous to ebullition is much 
 
STEAM-BATH. — WATER-BATH. 181 
 
 higher than in the opposite case. While the bath is in use, 
 care must be taken that the amount of the liquid in the outer 
 vessel remains as nearly as possible the same throughout the 
 process, and the loss from evaporation or exit of vapor should 
 be replaced by frequent but gradual additions of the same 
 fluid. 
 
 Steam-hath. — This apparatus forming a fixture of the labo- 
 ratory has been fully described at p. 42, Fig. 11. It is a 
 convenient arrangement for heating those substances which 
 would be alike injured by the direct application of fire or 
 contact of steam. It aiTords a temperature of fully 212° F. 
 
 For very small operations, the apparatus of Dr. Ure, Fig. 149, 
 is an excellent contrivance. pjg j49 
 
 " It consists of a tin box about « -« 
 
 18 inches long by 12 broad J \ - — /[ ■ 
 
 and 6 deep. The bottom is p^^^r-^ — Mn 
 
 hollowed a little by the ham- ..k::::^. £i— 
 
 mer towards its centre, in ~ \/ 
 
 which a round hole is cut of :^ r — ^"-^ 
 
 five or six inches in diameter. \\ / (^=^^ 
 
 Into this a tin tube three or \M \ 
 
 four inches long is soldered. ^-^ ) 
 
 This tube is made to fit tightly 
 
 into the mouth of a common tea-kettle, which has a movable 
 handle. The top of the box has a number of circular holes 
 cut in it of difierent diameters, into which evaporating cap- 
 sules of platinum, glass, or porcelain are placed. When the 
 kettle filled with water and with its nozzle corked is set on a 
 stove, the vapor playing on the bottom of the capsules heats 
 them to any required temperature ; and being itself continu- 
 ally condensed, it runs back into the kettle to be raised again 
 in ceaseless cohobation. With a shade above to screen the 
 vapor chest from soot, the kettle may be placed over a com- 
 mon fire. The orifices not in use are closed with tin lids. In 
 drying precipitates, the tube of a glass funnel may be corked 
 and placed with its filter directly into the opening of a proper 
 size. For drying red cabbage, violet petals, &c., a tin tray 
 is provided, which fits close to the top of the box within the 
 rim which goes about it. The round orifices are left open 
 when this tray is applied." 
 
 Water-bath. — The water-bath is used for heating those 
 substances which require a temperature lower than that of 
 
182 CONSTRUCTION OF WATER-BATH. 
 
 boiling water. It is very available where bodies easily de- 
 composable by high temperatures are to be heated, and is also 
 useful for the gradual exhaustion of vegetable and other sub- 
 stances which only give up their soluble matter after long 
 contact with the warm solvent liquid. Though seldom em- 
 ployed for the purpose of reducing the temperature very low, 
 it may, by proper management, be made to yield any inter- 
 mediate temperature from 32° to 212° F. 
 
 Every water and liquid bath, whatever its form and the 
 purpose to which it is to be applied, should be so constructed 
 that the vaporized portions can, if necessary, be confined 
 within the vessel and prevented from escaping by other outlets 
 than the safety valve. As proximity of the escaping vapor 
 might be injurious to the substance under process, the escape 
 pipe should have its exit six or eight inches distant from the 
 sides of the vessel. 
 
 Any two vessels of different diameters, one within the other, 
 may form a water-bath, provided the intervening space at the 
 bottom and sides is sufficient to contain the requisite amount 
 of water. Straw at the bottom and sides is an excellent 
 means of steadying the inner vessel and preventing direct 
 contact of its surface with the more highly heated bottom of 
 the outer vessel, a result which would cause the temperature 
 of the inner vessel to be raised above that of the surrounding 
 water. 
 
 Fig. 150. 
 
 A regularly constructed water-bath of convenient form is 
 shown in Fig. 150. "A is the vessel containing the water, 
 a the inner flange for the support of the evaporating dish B, 
 
CONSTRUCTION AND USE OP WATER-BATH. 183 
 
 or different circular rings when smaller dishes are employed. 
 c2 is a tube furnished with a stop-cock for the escape of the 
 steam, which, in some cases, requires to be carried still farther 
 off by an additional tube attached to it. The whole apparatus 
 may be heated either by a gas-stove or on a charcoal furnace. 
 The water-bath is filled about half-full with water. It will be 
 seen that water-baths with cover act more on the principle of 
 steam-baths as soon as the quantity of water which they con- 
 tain is small. Care must be taken always to replenish the 
 evaporating water by adding fresh, otherwise not only the 
 experiment may be ruined, but the bath itself become seriously 
 injured." 
 
 Large tin cups make excellent water-baths for flasks and 
 tall vessels. The bottom of the flasks may rest upon small 
 straw rings which prevent contact with the heated tin and 
 serve also to steady them. The holes in the lid for the pro- 
 trusion of the necks of the flasks also assist 
 in this latter respect. ^^^- ^^^• 
 
 A very convenient little bath for very small 
 operations, is shown in Fig. 151. It consists 
 of a copper capsule a, with a ledge around its 
 interior circumference as a rest or support for 
 the vessel to be heated. In order that it may 
 be applicable to capsules of any size, its top is 
 fitted with a series of thick flat copper rings, which afford the 
 power of decreasing the diameter of the outer capsule to suit 
 that of the vessel to be heated. 
 
 The whole diameter of the outer vessel is about 7 inches, 
 and when all the rings are placed upon the top the opening 
 in the centre is about 1 inch, but by withdrawing one at a 
 time the size of the mouth can be increased gradually from 1 
 to 6J inches and adapted to any vessel of intermediate size. 
 It would be well to have a small tube projecting from the side 
 so as to answer at the same time the purpose of a handle, and 
 of an exit pipe for the waste vapor. 
 
 This apparatus, as is seen in the figure, is mounted upon a 
 tripod 6, a convenient support when the small spirit lamp is 
 used to heat the water. When a stronger heat is required it 
 can be detached and mounted upon a larger support and 
 placed over the gas or Berzelius lamp. Fig. 152 represents 
 the apparatus without the tripod and with handles. 
 
 A porcelain or tin plate placed upon the top of this bath 
 
184 
 
 SALINE BATHS. 
 
 Fig. 152. 
 
 renders it very convenient for drying small filters, precipi- 
 tates, &c. By increasing the circumference of 
 the bath so that it may have a broad top, and 
 by piercing the latter with circular holes of 
 various diameters, we obtain a means of heat- 
 ing several capsules of different sizes at the 
 same time. Water-baths are useful for ex- 
 hausting organic and other matters readily 
 destructible by heat. For the completion of evaporations 
 which have been carried to the safest extent upon a sand-bath, 
 they are also very available. 
 
 The still, Fig. 13, without its^head makes an excellent water- 
 bath for large operations. 
 
 Saline baths. — The substitution of saline solutions for water 
 affords a means of obtaining temperatures higher than the 
 boiling point of that liquid. This kind of bath is very useful 
 for digestions and many other operations. The saturation of 
 the water with salts raises its point of ebullition, but in 
 practice it is necessary to use weaker solutions, otherwise the 
 evaporation of the water would be continually causing the 
 deposition of the salt and the solidification of the liquid to 
 the great inconvenience of the experimenter. 
 
 The following table exhibits the boiling points of the satu- 
 rated solution of the salts most generally employed for this 
 purpose. 
 
 BOILING POINTS OF SATURATED SOLUTIONS. 
 
 Alum - - - . 
 
 - 220° 
 
 Carbonate of potassa 
 
 - 2840 
 
 Muriate of ammonia 
 
 - 236 
 
 Chloride of zinc 
 
 - 320 
 
 Oxalate of ammonia 
 
 . 218 
 
 Rochelle salt - 
 
 . 246 
 
 Tartrate of ammonia 
 
 - 230 
 
 Sulphate of nickel - 
 
 . - 235 
 
 Chloride of barium 
 
 - 222 
 
 Chlorate of potass - 
 
 - 218 
 
 Nitrate of baryta 
 
 - 214 
 
 Nitrate of potass 
 
 - 238 
 
 Acetate of copper - 
 
 . 214 
 
 Quadroxalate of potass 
 
 - 220 
 
 Sulphate of copper - 
 
 - 216 
 
 Acetate of soda 
 
 - 256 
 
 Acetate of lead 
 
 - 212 
 
 Nitrate of soda 
 
 - 246 
 
 Chloride of calcium 
 
 . 220 
 
 Biborate of soda 
 
 . 222 
 
 Sulphate of magnesia 
 
 - 222 
 
 Carbonate of soda - 
 
 - 220 
 
 Cream of tartar 
 
 . 214 
 
 Phosphate of soda - 
 
 . 222 
 
 Chloride of sodium 
 
 - 224 
 
 Nitrate of strontia - 
 
 - 224 
 
 Tartrate of potassa 
 
 . 224 
 
 Sulphite of zinc 
 
 - 220 
 
 Sulphate of goda - 
 
 . - 213 
 
 Boracic acid - 
 
 - 218 
 
 Chloride of zinc is included in the above table, because of 
 is great deliquescence and availability at temperatures below 
 320° F. Beyond that degree it gives off fumes of chlorhydric 
 
METALLIC — OIL — SAND-BATHS. 185 
 
 acid and becomes inconvenient as a medium for the commu- 
 nication of heat. A layer of oil retards the evaporation of 
 the water and promotes the elevation of the temperature of 
 the solution. 
 
 The selection of the ^alt for the bath must be with regard 
 to economy and the nature of the material of the vessels. 
 Corrosive solutions should only be used in those vessels upon 
 which they are without action. The construction of the bath 
 is similar to that shown in Fig. 150. 
 
 Metallic baths. — These baths are only convenient for small 
 operations, because of the difficulty of supporting the weight 
 of a large amount of metal and of keeping the heating vessels 
 immersed in it. They furnish temperatures higher than either 
 of the preceding, and for greater safety must be heated in 
 cast iron vessels of form suitable to the experiment. 
 
 Mercury would be a convenient menstruum, if it was lighter 
 and emitted, when highly heated, less noxious fumes. On 
 these accounts it is but rarely used, and only in test tubes for 
 heating still smaller tubes. The fusible alloy, composed of 
 eight parts of bismuth, five of lead, and three of tin, forms an 
 excellent metallic bath. It melts below 212° F., and afibrds 
 very high temperatures, for though it oxidizes upon the sur- 
 face as its temperature is increased, it will bear a white heat 
 without emitting vapors. Tin melting at 441° F. and lead 
 at 609° F., are both available for a temperature above their 
 fusing points. 
 
 Oil baths. — Oils in ebullition throw off a very disagreeable 
 vapor, but are otherwise convenient for furnishing tempera- 
 tures above their boiling point. Care should be taken not to 
 apply heat sufficient for their decomposition. Even at low 
 temperatures they have the advantage over water, of losing 
 less by evaporation and of affording facility in regulating the 
 temperature by means of an immersed thermometer. The oil 
 should, before its transfer to the bath, be heated in an iron 
 capsule for several hours, to expel moisture. The bath consists 
 of a porcelain lined or metallic jacket, of construction exactly 
 similar to that of the water-bath. It affords a temperature of 
 570° F., and the facility of determining its temperature, for 
 which purpose a thermometer is a necessary accompaniment. 
 
 Sand-bath. — This bath is of more general application for 
 laboratory purposes than either of the others. Its different 
 forms and their appropriate uses have already been fully de- 
 
186 THE PORTABLE LABORATORY. 
 
 scribed at pp. 38, 39, Figs. 8, 28, 92, 94. Sand is used, 
 because it is a better resistant of sudden changes of tempera- 
 ture, and affords a uniform heat greater or less as may be 
 required than that of the water baths. Magnesia and ashes 
 are sometimes substituted, but they are too apt to be driven 
 about by the least current of air; the former is only used as a 
 bed for platinum, or porcelain crucibles, which are to be en- 
 closed in Hessian crucibles and ignited. 
 
 A sand-bath may be readily constructed by filling an iron 
 pot with sand and placing it upon the charcoal furnace. Fig. 
 87, or upon the top of the stove which heats the apartment. 
 It is then ready to receive glass or porcelain vessels in which 
 the processes of evaporation, digestion, or distillation may be 
 carried on. 
 
 THE PORTABLE LABORATORY. 
 
 Having referred to each separate implement employed as a 
 means of applying heat in the various chemical operations, we 
 now call attention to a convenient, compact, and really elegant 
 apparatus, of German invention and construction, which may 
 very appropriately be styled a portable laboratory. It com- 
 bines within a less space than four square feet, every requisite 
 for convenient manipulations in any process for which a fur- 
 nace is required. 
 
 We are indebted for the drawing Fig. 153, to iHolir's 
 Clommentar ^tir JJrensiscljen JJljarmacopcE. The furnace and 
 grate are of iron, and can be set wherever it is convenient, 
 adjoining a flue. The accompaniments are a tin lined copper 
 still with pewter head and worm, a block tin digesting cup ; 
 two other digesting cups, one of glass and the other of por- 
 celain, protected exteriorly by copper jackets. A large tinned 
 copper evaporating basin, another similar basin with a por- 
 celain interior, and a half score of other convenient and useful 
 vessels. The furnace is so constructed that the furniture may 
 be heated either by the naked fire or by steam, a generator 
 for which surrounds the body of the still. The cooler for the 
 worm, is a large copper cylinder of some twenty gallons 
 capacity, tinned and arranged interiorly and fitted with pipes, 
 adapting it to all the purposes of maceration, decoction, solu- 
 
THE PORTABLE LABORATORY. 
 Fig. 153. 
 
 187 
 
 tion, and ebullition. A sand-bath for heating glass and por- 
 celain vessels also forms part of the apparatus. 
 
 Weiss and Schively, No. 43 north Front st. Philadelphia, 
 have lately imported an apparatus somewhat after the plan 
 of our drawing, the first one we believe that has appeared or 
 been offered for sale in this country. We cannot too highly 
 commend these implements to the attention of the druggist. 
 
188 THE MODE OF PRODUCINa LOW TEMPERATURES. 
 
 Where the means will justify the outlay, every pharmaceutical 
 workshop should be provided with one. It would not only 
 facilitate the preparation of products, but would also afford 
 the means of pursuing investigations, and thus of inducing the 
 operator to contribute to the advancement of science. 
 
 CHAPTER XIII. 
 
 THE MODE OF PRODUCING LOW TEMPERATURES. 
 
 A LOW degree of temperature is often as necessary in some 
 chemical processes as an elevated one is in others. The 
 means of obtaining it are by freezing mixtures, and these 
 mixtures are formed of materials prone to liquefaction. The 
 abstraction of the heat requisite for this purpose, from the 
 bodies with which they are in contact, produces in them a 
 corresponding decrease of temperature. 
 
 In many chemical investigations they are particularly use- 
 ful, especially for determining the freezing point of substances, 
 and as cooling media for the recipients in the various pro- 
 cesses of Distillation. The components of freezing mixtures 
 should be finely pulverized, and the whole formed as rapidly 
 as possible. Bulbs and small vessels with their contents may 
 be cooled, but not economically, by keeping their surfaces 
 moistened with ether or some other very volatile matter 
 which, by rapid vaporization, can carry off a large amount of 
 heat. 
 
 The following convenient tables by Walker and Karsten, 
 exhibit the composition of numerous freezing mixtures and 
 the degree of cold which they produce. 
 
 ® 
 
FREEZING MIXTURES. 
 
 189 
 
 Table I. Consisting of Frigorific Mixtures, composed of Ice, with Chemical 
 Salts and Acids. 
 
 Mixtures. 
 
 C Snow or pounded ice 
 
 ( Muriate of soda - - 1 
 
 ( Snow or pounded ice - 5 
 
 < Muriate of soda - - 2 
 ( Muriate of ammonia - 1 
 C Snow or pounded ice 24 
 
 J Muriate of soda - 10 
 
 j Muriate of ammonia - 5 
 
 (^ Nitrate of potash - - 5 
 
 rSnow or pounded ice 12 
 
 < Muriate of soda - - 5 
 (_ Nitrate of ammonia - 5 
 C Snow - - - -3 
 ( Diluted sulphuric acid* - 2 
 5 Snow - - - - 8 
 ( Muriatic acid (concentrated) 5 
 C Snow - - - -7 
 I Concentrated nitrous acid 4 
 C Snow - - - - 4 
 ( Muriate of lime - - 5 
 5 Snow - - - - 2 
 ( Crystallized muriate of lime 3 
 
 Snow - - - -3 
 
 Potash - - - - 4 
 
 Thermometer sinks. 
 
 Degree of cold 
 produced. 
 
 2 parts i 
 
 to— 5° 
 
 to— 12« 
 
 to— 18° 
 
 to —25° 
 I From 4-32° to —23° 
 
 From 4-32° to —27° 
 
 From 4-32° to —30° 
 
 From 4-32° to —40° 
 
 From 4-32° to —50° 
 
 From 4-32° to —51° 
 
 55° 
 
 59 
 
 62 
 
 72 
 
 82 
 
 83 
 
 N.B. The reason for the omissions in the last column of this table is, 
 the thermometer sinking in these mixtures to the degree mentioned in the 
 preceding column, and never lower, whatever may be the temperature of the 
 materials at mixing. 
 
 Table II. Consisting of Frigorific Mixtures, having the power of generating 
 or creating Cold, without the aid of Ice, sufficient for all useful and philo- 
 sophical purposes, in any part of the world at any season. 
 
 Mixtures. 
 
 C Muriate of ammonia - 5 parts 
 
 < Nitrate of potash - - 5 " 
 
 ^ Water ... 16 " 
 
 f Muriate of ammonia - 5 " 
 
 J Nitrate of potash • - 5 " 
 
 ] Sulphate of soda - - 8 " 
 
 [Water ... 16 « 
 
 C Nitrate of ammonia 
 ( Water • 
 
 S Nitrate of ammonia 
 Carbonate of soda - 
 Water - 
 
 Thermometer sinks. 
 
 From -f 50° to 4-10° 
 
 Degree of cold 
 produced. 
 
 40° 
 
 ^From -f 50° to 4-4° 
 
 ? From +50° to -f 4° 
 > From +50° to —7° 
 • Strong acid 2 parts ; water or snow 1 part, by weight. 
 
 46 
 
 46 
 
 57 
 
190 
 
 FREEZING MIXTURES. 
 
 Mixtures. 
 
 ( Sulphate of soda 
 ( Diluted nitrous acid* 
 r Sulphate of soda 
 J Muriate of ammonia 
 J Nitrate of potash 
 [^Diluted nitrous acid 
 C Sulphate of soda 
 
 < Nitrate of ammonia 
 ( Diluted nitrous acid 
 C Phosphate of soda - 
 ( Diluted nitrous acid 
 C Phosphate of soda - 
 
 < Nitrate of ammonia 
 ( Diluted nitrous acid 
 C Sulphate of soda 
 
 ( Muriatic acid - 
 
 ( Sulphate of soda 
 
 \ Diluted sulphuric acidj" 
 
 __ ^ , Degree of cold 
 
 Thermomeier sinks. produced. 
 
 ^^^^^ I From +50° to —3° 
 
 " 1 
 
 " J^From -f50o to —10° 
 
 " J 
 
 « > From 4-50° to —14° 
 
 (( V 
 
 " ^From+50° to— 12° 
 
 " > From 4-50° to —21° 
 
 I I From -f 50° to 0° 
 
 II I From 4-50° to +3° 
 
 53° 
 60 
 
 64 
 
 62 
 
 71 
 
 60 
 47 
 
 N. B. If the materials are mixed at a warmer temperature than that expressed 
 in the table, the effect will be proportionately greater; thus, if the most powerful 
 of these mixtures be made when the air is4-85°, it will sink the thermometer 
 to-f2°. 
 
 Table III. Consisting of Frigorific Mixtures selected from the foregoing tables' 
 and combined so as to increase or extend Cold to the extremest degrees. 
 
 Mixtures. 
 
 C Phosphate of soda - 
 < Nitrate of ammonia 
 ^ Diluted nitrous acid 
 C Phosphate of soda - 
 ^ Nitrate of ammonia 
 ( Diluted mixed acids 
 
 Snow 
 
 Diluted nitrous acid 
 ( Snow - - - 
 ^ Diluted sulphuric acid 
 ( Diluted nitrous acid 
 \ Snow - - - 
 ( Diluted sulphuric acid 
 5 Snow - - - 
 I Muriate of lime 
 ( Snow ... 
 ( Miuiate of lime 
 
 Snow ... 
 
 Muriate of lime 
 
 5 parts 
 
 3 
 
 4 
 
 3 
 
 2 
 
 4 
 
 3 
 
 2 
 
 8 
 
 3 
 
 3 
 
 1 
 
 1 
 
 3 
 
 4 
 
 3 
 
 4 
 
 2 
 
 3 
 
 Thermometer sinks. 
 From 0° to —34° 
 
 ^From— 34°to— 50° 
 
 I From 0° to —46° 
 
 i From —10° to —56° 
 
 I From —20° to —60° 
 ( From 4-20° to —48° 
 ^From4-10° to— 54° 
 I From —15° to —68° 
 
 Degree of cold 
 produced. 
 
 34° 
 
 16 
 
 46 
 
 46 
 
 40 
 68 
 64 
 53 
 
 * Fuming nitrous acid 2 parts ; water 1 part, by weight, 
 t Equal weights of strong acid and water. 
 
FREEZING MIXTURES. 
 
 191 
 
 Mixtures. 
 
 C Snow - - - - 1 part 
 
 ( Crystallized muriate of lime 2 " 
 
 CSnow - - - - 1 « 
 
 I Crystallized muriate of lime 3 " 
 
 i Snow - - - - 8 " 
 
 ( Diluted sulphuric acid 10 " 
 
 Thermometer sinks. 
 From 0° to — GG^' 
 From — 40° to — .73<' 
 I From —68° to —91° 
 
 Degree of cold 
 produced. 
 
 66° 
 
 33 
 
 23 
 
 Remarks. The above artificial processes for the production of cold are more 
 efiective when the ingredients are first cooled by immersion in other freezing 
 mixtures. In this way Mr. Walker succeeded in producing a cold equal to 
 100° below the zero of Fahrenheit, or 132° below the freezing point of water. 
 
 The materials in the first column are to be cooled, previously to mixing, to 
 the temperature required, by mixtures taken from either of the preceding tables. 
 
 The following table by Karsten, shows the diminution of temperature in 
 degrees Fah., where 1 pt. of salt is dissolved in 4 pts. water : — 
 
 FREEZING MIXTURES. 
 
 Salts. 
 
 Nitrate of lead 
 
 " baryta ------ 
 
 Common salt 
 
 Sulphate of copper --.--. 
 
 " potassa - I - - - 
 
 " zinc ------ 
 
 " magnesia - - - - - 
 
 Muriate of baryta 
 
 Sulphate of soda ------- 
 
 Nitrate of soda 17-0° 
 
 « potassa - - 19-1° 
 
 Chloride of potassium 21*3° 
 
 Nitrate of ammonia - - 25-4° 
 
 Muriate of ammonia 27*3° 
 
 The following table, also by Karsten, shows the degrees of cold produced by 
 dissolving 1 pt. of a salt in 4 pts. of a saturated solution of another salt : — 
 
 Degrees of cold. 
 
 3-4° 
 3-8° 
 3-8° 
 4-0° 
 5-2° 
 6-6° 
 S-P 
 8-1° 
 - • 14-6° 
 
 Salts. 
 
 Sat. solution of 
 
 Degrees of cold 
 
 Sal ammoniac 
 
 Common salt 
 
 - 15-1° 
 
 " 
 
 Saltpetre - 
 
 - 22-7° 
 
 Saltpetre 
 
 Sal ammoniac - 
 
 - 17-5° 
 
 « . , 
 
 Common salt 
 
 - 16-9° 
 
 « 
 
 Nitrate of soda - 
 
 - 12-7° 
 
 (C . . 
 
 « baryta 
 
 - 17-5° 
 
 / " . - 
 
 lead - 
 
 - 17-1° 
 
 Glauber'8 salt 
 
 Common salt 
 
 8-5° 
 
 Common salt 
 
 Blue vitriol 
 
 7-4° 
 
 Nitrate of soda - 
 
 Sal ammoniac - 
 
 - 16-4° 
 
 (( 
 
 Saltpetre - 
 
 - 16-6° 
 
 i( 
 
 Common salt 
 
 - 14-0° 
 
 (( 
 
 Muriate of baryta 
 
 4-9° 
 
 « 
 
 Nitrate of lead - 
 
 - ]4-4° 
 
 Nitrate of baryta 
 
 Saltpetre - 
 
 1-35° 
 
 Sulphate of zinc - 
 
 Sulphate of potassa 
 
 31° 
 
192 FUSION. — CRUCIBLES. 
 
 The following table, by Karsten, of 1 pt. salt in 4 pts. of a saturated solution, 
 shows an increase of temperature : — 
 
 Salts. 
 
 Sat. solution of 
 
 Degrees of heat. 
 
 Common salt 
 
 Sal ammoniac 
 
 8-2° 
 
 « - . 
 
 Glauber's salt 
 
 . - . 31° 
 
 « . . 
 
 Saltpetre - 
 
 1-35° 
 
 " - . 
 
 Nitrate of soda 
 
 6-8° 
 
 Muriate of baryta 
 
 (( 
 
 115° 
 
 By mingling solid lead amalgam with solid bismuth amalgam, whereby they 
 become liquid, Orioli obtained 39-6° of cold. Dobereiner mixed 204 pts. lead 
 amalgam (103 lead, -f- 101 mercury) with 172 pts. bismuth amalgam (71 bis- 
 muth -|- 101 mercury), and obtained a diminution of from 68° to 302; and by 
 adding to the same 202 pts. more of mercury, the temperature fell to 17-6°. By 
 dissolving the powders of 59 pts. tin, 1035 pts. lead and 182 pts. bismuth, in 
 808 pts. mercury, the thermometer falls from 635° to 14°. 
 
 CHAPTER XIV. 
 
 FUSION. 
 
 The liquefaction of bodies by heat, a preliminary step to 
 many processes, is termed fusion. Igneous fusion applies to 
 the melting of anhydrous substances, and aqueous fusion to 
 the liquefaction of a salt in its water of crystallization. 
 
 The modes of performing the process, and the material and 
 form of the apparatus employed, vary with the nature of the 
 substance to be acted upon. The chief point to be attended 
 to is the selection of such containing vessels as are not inju- 
 riously aflfected by the fused substance — and which do not 
 themselves react upon their contents. 
 
 The implements for fusion are called crucibles, the smaller 
 of which, for the less refractory substances, may be heated 
 over the gas or spirit lamp. To effect the liquefaction of 
 bodies difficultly fusible or of large quantities of matter, a 
 FURNACE is requisite. 
 
 The size of the crucible should be proportional to the quan- 
 tity of matter to be heated in it. It is best that its capacity 
 should be no greater than sufficient for the contained substance 
 with enough margin to allow for swelling or foaming. 
 
 Crucibles. — A crucible, to be available for any and every 
 operation should possess the quality of compactness in order 
 
CLAY — HESSIAN — LONDON — FRENCH CRUCIBLES. 
 
 193 
 
 Fig. 154. 
 
 to resist the corrosive action of fused substances, the permea- 
 bility of gases and liquids, the fusing power of intense heat, 
 and the tendency to fracture by sudden changes of tempe- 
 rature. 
 
 It is impossible to combine all these requisites in any one 
 kind of crucible. 
 
 The materials of which crucibles are formed are either pure 
 clay, or clay mixed with charcoal, quartz, graphite or coke, to 
 render it more refractory. Black lead, porcelain, silver or 
 platinum, have each and all their appropriate application. 
 
 Olay Crucibles. — The Hessian and French crucibles are 
 those of this description, which are most used. The Hessian, 
 so called from the place of their manufacture in 
 Germany, are either in the form of a tapering 
 cylinder or triangular, and are of that kind of 
 crucible most commonly found at our drug shops. 
 They are met with in nests of a half dozen or 
 more, gradually increasing in size from the small- 
 est (of an ounce) to the largest, of pint or quart 
 capacity. 
 
 They are grayish yellow or whitish, rough to 
 the touch, and should give a clear ring when held by the bot- 
 tom and sounded on the sides. Being hard and impermeable, 
 they are very useful for rough fusions ; but the silica which 
 they contain renders them unfit for metallic oxides, with which 
 at high heat it combines. 
 
 The Hessian crucibles require careful usage, as they are 
 liable to be fractured by even slight changes of temperature. 
 Therefore, notwithstanding their great cheapness, the London 
 or French crucibles are more preferable for nice operations. 
 
 The London crucibles are very refractory, regularly formed 
 with smooth surfaces, and will endure a very high heat. 
 
 The French crucibles. Fig. 155, which are manufactured 
 by Beaufaye, of Paris, are said to be far superior 
 to either of the preceding. They are whitish, 
 well-shaped and smooth throughout, and being 
 nearly free from oxide of iron, and less rich in 
 silica, are applicable for the fusion of nearly all 
 substances except certain salts, which, owing to 
 the porosity of the crucible material, are readily 
 absorbed. 
 
 Being capable of supporting extreme heat as well 
 as sudden changes of temperature, they are very 
 
 Fig. 155. 
 
194 BLACK LEAD CRUCIBLES. — BLUE POTS. 
 
 useful for the reduction of oxides and fusion of metals. 
 Borax, glass and similar substances remain perfectly colorless 
 when melted in these crucibles. 
 
 The mixture of graphite or coke with the clay, which is 
 found in those of Austin's make, renders them capable of 
 better supporting the softening influence of the wind furnace 
 and withstanding the most sudden changes of temperature, 
 but the proportion of the latter must not exceed 33 per cent., 
 otherwise its combustion by the fire will leave the crucible 
 porous and fragile. 
 
 As metallic oxides are reducible when hot, by contact with 
 carbonaceous matter, these crucibles, when used for heating 
 those substances, should be lined with a thick coat of clay 
 paste and dried. 
 
 Charcoal is the only proper fuel for earthen crucibles, as 
 coke is apt to form scoriae which attach to the crucible and 
 impede the draught. 
 
 Black Lead Crucibles. Blue Pots. — Black lead or plum- 
 bago when mixed with one-fourth of its weight of refractory 
 clay becomes capable of supporting intense heat and sudden 
 changes of temperature. The chief use of crucibles made of 
 this substance is in metallurgy, for the purposes of which their 
 smooth surface admirably adapts them. They are not suffi- 
 ciently compact for the fusion of salts. 
 
 Porcelain Crucibles. — Crucibles of this material are very 
 neat implements, but by reason of their incapability of resist- 
 ing even slight changes of temperature, are only used for 
 purposes to which those of more refractory material are for 
 other reasons not adapted. For heating over the lamp they 
 must be small and thin. In analytic and nice operations they 
 replace platinum in many processes in which the contents act 
 upon that metal, for example, in igniting plumbic precipi- 
 tates, melting metallic oxides with sulphobases, preparing 
 enamels, and heating metallic oxides which are reduced easily 
 in contact with platinum. 
 
 The crucibles. Figs. 156, 157, used directly over the lamp, 
 should never exceed an ounce in capa- 
 
 Fig. 156. Fig. 157. g-^^^ f^j. ^^gj^ ^i^i^ ^^Q jjjQgl- careful 
 
 management it will be difficult to cool 
 one of larger size gradually enough to 
 prevent its breaking. Berzelius recom- 
 mends their insertion in platinum cru- 
 cibles as a means of diminishing their 
 
 KJ 
 
PORCELAIN — METALLIC CRUCIBLES. 
 
 195 
 
 fragility. The French porcelain being very thin and light, 
 and a better supporter of sudden changes of heat, is preferable 
 to the Berlin for small crucibles. 
 
 The impermeability and cleanliness of these crucibles, ren- 
 der them very convenient for the fusion of certain nice sub- 
 stances, such as nitrate of silver, potassa, &c., in large 
 quantities, and as it is impracticable to have a very large 
 platinum crucible in private laboratories, one of porcelain is 
 substituted. These large crucibles, made with covers, may 
 be of either of the forms. Figs. 158, 159, 160, and of Berlin 
 porcelain, which is similar to wedgewood-ware, and heavier 
 and cheaper than the French. 
 
 Fig. 158. 
 
 Fig. 159. 
 
 Fig. 160. 
 
 Fig. 161 
 
 ^ 
 
 The large crucibles, varying in size from two to six inches 
 in height, and from one to four inches in diameter, may be 
 entirely biscuit or else glazed only internally, and if heated 
 over the fire require to be enclosed in a refractory fire-clay 
 case, as shown in Fig. 161. This case is equally useful for pla- 
 tinum or silver crucibles (Fig. 120), as it gives them a proper 
 elevation above the grate and prevents contact with the coals. 
 
 For the heating of more readily fusible substances they 
 may be imbedded in a sand-bath and heated up gradually. 
 If allowed to remain in the bath until it has cooled the lia- 
 bility of fracture from sudden refrigeration will be diminished. 
 
 Some of the crucibles have duplicate covers, one of which 
 is perforated and used to facilitate the escape of the gaseous 
 matter generated during certain processes. 
 
 Metallic Crucibles. — Cast and plate iron, silver and pla- 
 tinum are all used as materials for crucibles. 
 
 Iron Crucibles. — For the fusion of silicates and certain 
 seleniurets, sulphurets and other substances, iron crucibles 
 are very convenient. An exterior coating of clay is requi- 
 site to protect them from the oxidizing action of the air, to 
 
196 IRON — SILVER — PLATINUM CRUCIBLES. 
 
 which they are subjected at high temperatures. The same 
 object may be eflPected by inserting them in clay crucibles. 
 
 When, however, the heating is not 
 Fig. 162. Fig. 163. of long duration nor intense they 
 
 may be used naked. 
 O \^=^^^ Those of wrought iron. Fig. 162, 
 
 are struck up from a single piece of 
 thick sheet metal. 
 
 Cast iron crucibles. Fig. 163, are 
 cheaper, and equally as good as 
 wrought iron for medium tempera- 
 tures, but they must be turned 
 smooth interiorly. 
 As some of the constituents of stove coal exert a chemical 
 action upon metal, the only proper fuel is charcoal. 
 
 Silver Crucibles. — Silver crucibles are but rarely used, save 
 for the fusion of potassa, soda, and for the preparation of 
 caustic baryta from the nitrate. For most operations they 
 are well replaced by platinum. For acid substances their 
 use is improper. The spirit or gas lamp is the heating appa- 
 ratus, but the heat must not be too high nor of too long dura- 
 tion, for the silver is apt to become brittle in spots as it 
 assumes a crystaline form under the influence of long con- 
 tinued red heat. 
 
 Platinum Crucibles. — Platinum crucibles are of more ge- 
 neral application than those of any other material. They 
 are very tough and infusible at any heat that can be obtained 
 from the gas or spirit-lamp, the almost exclusive means em- 
 ployed for that purpose. As they are liable to become rough 
 at high furnace temperatures, they should, when exposed to 
 Buch influences, be inserted in an earthen crucible, and sur- 
 rounded by a bed of magnesia. 
 
 Their strong resistance to the action of chemical re-agents 
 renders them indispensable in many operations, which it would 
 be difficult otherwise to perform. They vary in size from a 
 fluidrachm to three or more fluidounces capacity, the latter 
 being as large as is necessary for any pur- 
 Fig. 164. p^gg -j^ ^ private laboratory. Their form 
 
 is shown in Fig. 164. 
 pJi^ The crucibles intended to be heated over 
 r 1 the lamp must be of very thin metal, so 
 that they can be weighed, as is often neces- 
 
 D 
 
THE CONSTRUCTION OF CRUCIBLES. 197 
 
 sary, in a delicate balance. To give strength, however, the 
 bottom must be thicker than the sides. Two of the smaller 
 sized will be found more useful than one of the larger. In 
 analyses a half ounce crucible is indispensable for the ignition 
 of filters. 
 
 The cover is, as seen in the figure, slightly convex exteriorly, 
 and ledged around the circumference : this form is convenient 
 when the vessel is to be entirely closed when heated; but in 
 certain operations in the wet way it is reversed, so that the 
 convex side may look inwardly and return any particles of 
 its contents that may be projected upwards, by a too sudden 
 or intense elevation of temperature. The pin running through 
 its centre is the knob by which it is handled when cold with 
 the fingers, when hot with the tongs. Figs. 114, 127. 
 
 For evaporation the crucible takes the form of a capsule, 
 as is seen in Fig. 165, which represents 
 one with a lip and handle. ^^s- 165, 
 
 Unless the crucibles are made of per- 
 fectly pure metal, and are hammered out 
 instead of turned, their power of enduring 
 strong heats and resisting the action of 
 chemical reagents will be impaired. The blisters and flaws 
 which appear, after use, are owing to impurity and bad work- 
 manship, and are to be removed by the force of a small 
 hammer. 
 
 When the crucible becomes cracked or perforated it can be 
 repaired by welding on a layer of platinum sponge, biit it is 
 far better to have it melted up and remodeled by a manufac- 
 turer. (J. Bishop, Philadelphia.) 
 
 Boiling or hot water loosens adherent saline matters, and 
 fused borax or muriatic acid will remove all stains which do 
 not disappear by rubbing with sand or pumice stone. The use 
 of sharp pointed instruments will be apt to injure the crucible. 
 
 The experimenter himself can in any emergency readily 
 form a crucible out of platinum foil by shaping it with the 
 thumb or a small hammer, in a hemispherical cavity made in 
 a board for the purpose. 
 
 Berzelius {Traite de Ohimie, vol. viii.) gives the following 
 instructions as to the manner of using platinum crucibles. 
 
 " Dry fusion should never be effected in platinum crucibles: 
 1st. Caustic alkalies, nitrates of lime, baryta or strontia and 
 alkaline nitrates always attack the platinum. Alkaline sul- 
 
198 DIRECTIONS FOR HEATING CRUCIBLES. 
 
 phurets or sulphates with charcoal are still more injurious. 
 Metals when heated to their melting points alloy with it, and 
 hence lead, tin, antimony, &c., should never be even mode- 
 rately heated in it. Even their oxides, especially those of 
 copper, lead, bismuth and nickel, reduce at a hifrli heat by 
 contact with platinum, particularly if charcoal is present, the 
 two former at a lower temperature than the latter. Gold, 
 silver, copper and others can be reddened, but not melted in 
 platinum. Phosphorus or phosphoric acid and carbon readily 
 attack it. Sulphate of lead may be burned oiF in it with care, 
 but for the chloride, porcelain should be used. 
 
 Silica may be ignited in platinum, but it combines with 
 silicium at a heat beyond redness, and therefore they should 
 always be encased when heated in the fire, otherwise if in 
 contact, it will abstract it from the coals. 
 
 Nearly all liquids may be heated in platinum, except they 
 contain chlorine, bromine, iodine or nitro-muriatic acid. 
 
 For the fixed alkalies, gold is preferable to either silver or 
 platinum, upon which they have a more or less corrosive 
 action. 
 
 Directions for Heating Crucibles. — All the larger and 
 coarser crucibles are heated in furnaces. Their proper 
 position, a vertical one, is in the centre of the grate upon a 
 slight elevation. Ignited coals are placed at the bottom of 
 the grate and covered with alternate layers of unlit coke and 
 charcoal, of nut size, until the crucibie is surrounded up to 
 the level of its top with fuel. When the crucible is to be 
 strongly heated, it should be covered and the fuel heaped 
 over its top. In all cases the fire must be gradually raised 
 and steadily kept up, and the furnace only opened when fresh 
 additions of coal are necessary, as it is important that there 
 shall be no variation of the temperature in its interior. 
 
 After the completion of the operation, the crucible should 
 be allowed to cool with the furnace, or if taken out imme- 
 diately, placed upon a brick or bed of warm sand, otherwise 
 a too sudden change of temperature will cause its fracture. 
 The furnace tongs, Fig. 112, are conveniently shaped for this 
 purpose. 
 
 As it is occasionally necessary to poke the fire in order 
 that the fuel may settle previous to fresh additions, it will be 
 well to give the crucible a firm position upon a stand for the 
 purpose — the half of a fire brick for instance, so that in the 
 
FUSION OF SUBSTANCES UNALTERABLE BY HEAT OR AIR. 199 
 
 settling of the coal, there may be no risk of its being upset. 
 When by intense heat its bottom has become welded to 
 the brick, the latter can very readily be detached by a gentle 
 tap of the poker. 
 
 Most of the common crucibles serve only for a single 
 operation. 
 
 Covers may be made by inverting a smaller crucible over 
 the top ; or better, by making a dough of Stourbridge clay, 
 and luting it on. The crucible in the latter case must not 
 be heated until the cover has dried. These lids have a tend- 
 ency to retard volatilization and are necessary to prevent the 
 entrance of falling particles of coal and ashes. For the escape 
 of gaseous matter a small perforation in the centre of the 
 cover is necessary, but in intensely hot fusions all other open- 
 ings must be closed with lute. 
 
 The smaller metallic crucibles are almost exclusively heated 
 over LAMPS. They are supported upon wrought iron rings. 
 Figs. 12T, 133, the diameter of which may be reduced when 
 necessary, by the use of the wire triangles, fig. 134, of the 
 required size. 
 
 If the crucibles are very small they may be heated by the 
 mouth blow-pipe. For the larger an argand spirit or gas 
 lamp. Fig. 27, is needed. To hasten the process or to in- 
 crease the temperature, the table blow-pipe. Figs. 30, 127, 
 is convenient, as it gives a powerful blast. 
 
 The use of the jacket. Fig. 120, is an additional means of 
 still further economizing and increasing the power of the 
 flame. It also diminishes the loss of heat from the crucible 
 by radiation, especially when the latter is covered. In 
 charging the crucibles, the contents should be concentrated 
 into as small a space as possible, and any adherent particles 
 should be brushed from the sides with a feather. When the 
 crucibles are emptied of their fused contents, the melted 
 matter may be made to flow upon a smooth and clean slab of 
 marble, iron or other proper material — great care being taken 
 that it does not come in contact with any moisture or damp 
 substance. 
 
 Fusion of Substances unalterable by Heat or Air. — This 
 class comprises a very large number of substances, among 
 which are the noble metals, &c. The crucible employed 
 should be kept covered as well whilst cooling as heating, and 
 the refrigeration must be gradual or the molten matter may 
 
200 FUSION OF SUBSTANCES ALTERABLE BY HEAT AND AIR. 
 
 spirt. There are other metals again, for instance, zinc, 
 lead, tin, antimony, and bismuth, which at high temperatures 
 oxidize readily upon exposure. In such cases it is well, in 
 addition to keeping the vessel closed, to cover the fluid mass 
 with a layer of powdered charcoal. 
 
 When a metal is in process of fusion it is imprudent to 
 make fresh additions without having first heated the material 
 to be added, for the sudden entrance of cold or damp matter 
 into the hot fluid mass will cause the ejection of particles, 
 and perhaps serious inconvenience. 
 
 In the manufacture of alloys the metals should be well in- 
 corporated by occasional stirring. When iron, and indeed 
 manganese, cobalt, nickel and chrome, are being exposed to 
 high degrees of heat, the crucibles must be free from carbona- 
 ceous matter, otherwise a combination may ensue at high 
 temperatures. 
 
 Fusion of Substances alterable by Heat. — For the treat- 
 ment of substances which melt below 212° F., the water-bath 
 is convenient. The fusion of substances such as wax, resin 
 and fat, immiscible with that liquid, may be facilitated by the 
 direct application of boiling water, as they can be readily 
 removed from the surface to which they rise, with a ladle or 
 syphon whilst hot, or in a mass if allowed to cool. 
 
 Substances requiring a temperature at or below 550° for 
 their fusion, may be melted in an oil-bath. 
 
 Alloys containing volatile metals should be heated as quickly 
 as possible. 
 
 Certain substances which volatilize at low temperatures 
 require to be fused in closed vessels. Iodine and arsenic are 
 examples. 
 
 A tube of glass, porcelain or metal, according to the nature 
 of the substance, is the best form of apparatus for this pur- 
 pose. It should be rounded at one end, and after the intro- 
 duction of the substance, closed at the other over the blow- 
 pipe. 
 
 The tube must be heated throughout its length. 
 
 Fusion of Bodies alterable by Air. — This class of substances 
 is melted in seclusion, the air being shut out by means of an 
 intermedium of liquid, powder, or fusible matter. Thus potas- 
 sium is liquefied under naphtha ; phosphorus under water, and 
 certain other substances in powdered charcoal. 
 
FUSION OF DIFFICULTLY FUSIBLE SUBSTANCES. — IGNITION. 201 
 
 The covers of the crucibles in these cases must be tightly, 
 luted SO that all openings may be closed. 
 
 Fusion of difficultly fusible Substances. — All substances 
 which resist the fusing power of furnaces, are to be subjected 
 to the more intense action of the hydro-oxygen blow-pipe. 
 
 CHAPTER XV. 
 
 IGNITION. 
 
 Substances frequently require to be ignited to redness 
 either as the sole process of their preparation, or as a preli- 
 minary step to subsequent operations. 
 
 Ignition of Filters. — In analyses, the filters containing the 
 insoluble or precipitated substances which are to be estimated 
 are ignited or "burned off" to expel carbonaceous and vola- 
 tile matters, before being weighed. The implements for this 
 purpose are porcelain or platinum crucibles, either having 
 their appropriate application. 
 
 As it is necessary that the filter should be wholly or par- 
 tially dry, it must be carefully remoyed from the funnel, 
 so as not to lose a particle of its contents, compressed be- 
 tween the folds of bibulous paper, and, further, dried in a 
 capsule over a sand or water bath, or in a drying stove (De- 
 siccation), at a temperature of about 200° F. or less. The 
 dried filter is then to be transferred to the crucible which has 
 been previously weighed. The transfer must be made with- 
 out the loss of the least particle, and for this purpose the 
 crucible may be placed upon a sheet of glazed white paper, 
 so that any particles that accidentally fall may be pre- 
 served. The filter should be placed in the crucible with its 
 apex upwards, after having been freed as much as possible 
 from the adherent precipitate by gently rubbing the sides 
 together between the thumb and forefinger. The force used 
 for this purpose must not be sufiicient to abrade the paper, 
 otherwise the matter will reach the fingers, and a loss thus 
 be occasioned by adherence. The crucible is then heated 
 cautiously and gradually over the spirit or gas lamp. Fig. 
 14 
 
202 IGNITION OF BODIES IN VAPORS. 
 
 127, the flame of which may be urged by the blast. For the 
 first few moments the vessel should remain covered, for fear 
 of loss by decrepitation, but as soon as it becomes red-hot 
 the lid may be wholly or partially removed, and the crucible 
 slightly inclined, as at Fig. 27. This position allows the free 
 admission of air and the complete and rapid incineration of the 
 filter. This done, the cover is replaced, the crucible allowed 
 to cool, and then weighed. The weight of the crucible and 
 that of the ashes of the filter, which latter has been previously 
 determined by the incineration of filters of difi'erent sizes, de- 
 ducted from the total weight, gives the weight of the ignited 
 precipitate. 
 
 When substances are to be ignited for the determination of 
 their hygroscopic, volatile, or organic matter, the heat of the 
 lamp should be gradually applied without the blast, and, 
 for the former purpose, only to the production of a dull red 
 heat. In these instances, the crucible should be weighed first, 
 so that the loss sustained by a given weight of its contents 
 during ignition, may be ascertained in one weighing merely 
 by subtracting the weight of the crucible and contents after 
 ignition from the combined weight of the two before the same 
 process. The loss gives the amount of volatile matter. 
 
 In analyses of coals, the moisture can be determined by 
 heating the crucible in a hot sand-bath, or very gently over 
 a low flame. After the loss thus occasioned is determined by 
 weighing, the amount of carbon may be ascertained by sub- 
 jecting the crucible and contents to a much higher heat. 
 
 When substances are to be exposed to heat, the crucible 
 and contents must likewise be weighed separately before ig- 
 nition. The loss of weight gives the amount of volatile 
 matter driven off. The ignited matter can then be removed 
 from the crucible by hot water alone or acidulated. 
 
 Scorise may be removed from platinum crucibles by covering 
 them with a paste of borax and carbonate of soda, heating 
 them to redness, and when cold, dissolving out the saline 
 matter with boiling water. A repetition of the process is 
 necessary to brighten the crucible perfectly if it had been 
 very dirty. 
 
 Ignition of Bodies in Vapors. — If it be desired to heat 
 a fixed substance in the vapor of any body, which is solid or 
 liquid at ordinary temperatures, the latter may be put into a 
 tube closed at one end, or into a small flask with a long neck, 
 
IGNITION WITH FLUXES. 203 
 
 and then be heated until it is wholly vaporized. The substance 
 is to be introduced into the tube, and heated in the vapor at 
 any desired temperature. Thus, to show the affinity of sul- 
 phur for copper, the former is heated until its vapor fills the 
 whole flask, when slips of copper foil let down into it imme- 
 diately ignite on combining with the sulphur. When a tube 
 is used it may be held in any inclined position, but a flask 
 should be nearly vertical. 
 
 Ignition with Fluxes.—F\\i.xQ^ are certain substances usu- 
 ally saline, mixed with other bodies in order to promote their 
 fusion or decomposition by heat, and, to render them more 
 soluble in water and acids. All ignitions with fluxes in expe- 
 rimental operations are performed in crucibles over the spirit- 
 lamp or furnace fire, and for the fluxions of those substances 
 in which there is no reducible metallic oxide, platinum is by 
 far the best material. 
 
 The process is particularly useful in the analysis of the 
 sulphurets of alkaline earths, of many silicates and other ob- 
 stinate compounds and also in metallic operations. 
 
 The principal objects of fluxing are: — 
 
 1. " To cause the fusion of a body, either difficultly fusible, 
 or infusible by itself. 
 
 2. To fuse foreign substances mixed with a metal, in order 
 to separate the latter by its diff'erence of specific gravity. 
 
 3. To destroy a compound into which an oxide enters, 
 and which prevents the oxide being reduced by charcoal. 
 The silicate of zinc, for instance, yields no metallic zinc with 
 charcoal, unless it be mixed with a flux capable of combining 
 with the silica. 
 
 4. To prevent the formation of certain alloys, and con- 
 sequently the combination of some metals with others, as in 
 the case of a mixture of the oxides of manganese and iron 
 with a suitable flux, the iron is obtained in a state of purity, 
 w^hereas if no flux had been added, an alloy would have been 
 obtained. Gold and silver can be separated from many other 
 metals by means of a flux. 
 
 5. To scorify some of the metals contained in the sub- 
 stance to be assayed, and obtain the others alloyed with a 
 metal contained in the flux, as gold or silver with lead. 
 
 6. And lastly, a flux may be employed to obtain a single 
 button of metal, which otherwise would be obtained in glob- 
 ules." 
 
204 NON-METALLIC FLUXES. 
 
 Fluxes should always be pulverized, and whether mixed 
 directly with the substance before ignition, or added gradu- 
 ally to the crucible during the process, ought rather to be in 
 excess than in deficiency. In the fluxion of silicates the 
 material and flux are incorporated together before being 
 transferred to the crucible. 
 
 When the mixture is of a frothing nature, it is best to add 
 it to the crucible piecemeal and to heat it gradually, so as to 
 save the loss caused by ejection of particles. After the 
 whole has been placed in the crucible, the heat may be raised 
 and maintained until perfect fusion and the completion of the 
 process. 
 
 Fluxes are divided into non-metallic and metallic fluxes. 
 
 Non-Metallic Fluxes. — (Berthier, JEssais par la voie 
 Seche.) — Silica is employed frequently to cause the fusion of 
 some gangues in assays made at an elevated temperature. 
 Silica combines with all the bases, and forms with them bodies 
 termed silicates, which are more or less fusible. 
 
 Lime, Magnesia, and Alumina. — It is known that no 
 simple silicate is readily fusible, so that lime, magnesia, or 
 alumina are employed, according to circumstances, to reduce 
 a simple silicate to such a condition that it will readily fuse 
 in an assay furnace. Sometimes, to attain this end it is re- 
 quisite to use all the above-mentioned earths, for experience 
 has proved that as a general thing a mixed or double silicate 
 fuses more readily, and flows freer than a simple silicate. 
 
 Baryta. — Hydrate of baryta fuses at a low red heat, and 
 without loss of its water of crystallization, and for the first 
 reason is preferable to either the carbonate or nitrate. It is 
 used in silver or platinum crucibles, and when silicates are 
 to be tested for alkalies. The silicates of baryta, however, 
 fuse with difficulty, and are sluggish. 
 
 Grlass is a very useful flux in certain iron assays. The 
 kind employed must contain no lead. 
 
 Boracic Acid. — The native boracic acid, after fusion and 
 pulverization, is to be employed whenever the use of this acid 
 is indicated. It ought to be kept in well-stopped bottles. 
 
 Boracic acid has the property of forming with silica and 
 all the bases very fusible compounds, and is from this cause 
 a very universal flux. Nevertheless, there is an inconvenience 
 attached to its use; it is very volatile, so that sometimes the 
 greater part employed in an assay sublimes before it has had 
 time to perform its office. 
 
NON-METALLIC FLUXES. 205 
 
 Borax, Bihorate of Soda, is an excellent and nearly uni- 
 versal flux, because it has the property of forming, like boracic 
 acid, fusible compounds with silica and nearly all the bases, 
 and is preferable to that acid because it is much less volatile. 
 
 It may be used at a high or low temperature. In the 
 first case, it is employed in the assay of gold and silver be- 
 cause it fuses and combines with most metallic oxides, or in 
 obtaining a regulus, that is to say, to separate the metals, 
 their arseniurets and sulphurets, from any stony matter with 
 which they may be mixed, because this salt is neither oxidat- 
 ing nor desulphurating. In the second case, it is employed 
 in the assay of iron and tin ores, as in the presence of char- 
 coal it retains but traces of their oxides, and, indeed, much 
 less than generally remains with the silicates. 
 
 When borax is heated it fuses in its water of crystalliza- 
 tion, and undergoes an enormous increase of volume; at a 
 higher temperature, it fuses and forms a transparent glass, 
 which becomes dull on the surface by exposure to air. Only 
 the fused vitrified borax ought to be used in assays. It must 
 be reduced to powder, and kept in well-closed vessels. 
 
 Fluor Spar, Fluoride of Calcium, is rarely employed in 
 assays, but in certain cases is an excellent flux, especially 
 where sulphates are present, with many of which it forms 
 very fusible compounds. The best proportions are about 
 equal equivalents of the spar and the anhydrous sulphates of 
 alkali, lime, and oxide of lead : but for the sulphate of baryta, 
 two eqs. of the spar for one eq. of the sulphate. 
 
 It likewise assists in fluxing silicates, partly by direct 
 union with them, and partly by yielding fluosilicic gas, and 
 leaving lime to unite with silica. 
 
 Carbonate of Potash and Carbonate of Soda. — It has 
 been already proved that they possess oxidating and desul- 
 phurating power ; they will now be considered as fluxes. 
 
 They are decomposed in the dry way by silica and the 
 silicates, with the separation of carbonic acid. The presence 
 of charcoal much facilitates this decomposition. 
 
 The silicates of potassa and soda fuse readily and flow 
 freely. 
 
 They form fusible compounds with the greater part of the 
 metallic oxides ; in these combinations the oxide replaces a 
 certain quantity of carbonic acid ; but these compounds are 
 not stable, they are decomposed by carbon, which reduces the 
 oxide, or by water, which dissolves the alkali. 
 
206 FLUXES : — NITRE ; — SALT. 
 
 On account of their great fusibility, the alkaline carbonates 
 can retain in suspension, without losing their fluidity, a large 
 proportion of pulverized infusible substances, as an earth, 
 charcoal, &c. 
 
 The alkaline carbonates ought to be deprived of their 
 water of crystallization for assaying purposes ; in fact, it would 
 be better to fuse them before use. They must, in all cases, 
 be kept in well-stopped vessels. 
 
 They may be used indifferently, but carbonate of soda is to 
 be preferred as it does not deliquesce. 
 
 A mixture of both is far preferable to either alone, and 
 moreover requires a lower heat for its fusion. The proper 
 proportions are ten parts of efiloresced carbonate of soda and 
 thirteen parts of dry carbonate of potassa. The two are to be 
 intimately incorporated by trituration and the mixture kept in 
 stoppered bottles. This flux is the one of most general ap- 
 plication. 
 
 The alkaline carbonates of commerce always contain sul- 
 phates and chlorides. In ordinary cases, this causes no incon- 
 venience, but there are circumstances under which the pre- 
 sence of sulphuric acid would be injurious. 
 
 Carbonate of potash can readily be procured free from 
 sulphate and chloride by means of nitre and charcoal, as fol- 
 lows : — Pulverize roughly 6 parts of pure nitre, and mix them 
 with 1 part of charcoal ; then project the mixture spoonful by 
 spoonful into a red-hot iron crucible. The projection of each 
 spoonful is accompanied by a vivid deflagration, and car- 
 bonate of potash is found in a fused state at the bottom of 
 the crucible ; it must be pulverized, separated from excess of 
 charcoal, and kept in a dry state for use. 
 
 Carbonate of soda may be obtained in much the same way, 
 substituting nitrate of soda for nitrate of potash ; or by re- 
 peatedly crystallizing the carbonate of commerce. 
 
 Nitrate of Potash. — The presence of silica or silicates much 
 assists its decomposition. It is used as an oxidizing agent, 
 the potash resulting from its decomposition acting as flux. 
 To prevent violent action and ejection of particles of matter, 
 its addition to the crucible must be careful and gradual. 
 Nitre is also employed in some instances as a substitute 
 for nitrate of ammonia for effecting the rapid and perfect 
 combustion of organic substances. 
 
 Common Salt, Chloride of Sodium, was much recommended 
 
BLACK FLUX AND ITS EQUIVALENTS. 207 
 
 by the older assayers, either mixed with flux, or a certain 
 quantity placed above it, for the purpose of preserving the 
 substances beneath from the action of the atmosphere, or to 
 ameliorate the action of such bodies as cause much ebullition. 
 It is very useful in lead assays. When it is used, it must be 
 previously pounded and heated to dull redness in a crucible 
 to prevent its decrepitation. 
 
 Black Flux and its Equivalents. — Black flux is both a re- 
 ducing and fusing agent. It is a mixture of carbonate of 
 potash and charcoal in a minute state of division. It is much 
 employed, and very serviceable. It is prepared by mixing 2 
 parts of argol with 1 part of nitre, placing the mixture in an 
 iron vessel and setting it on fire by a burning coal or red-hot 
 rod. When the combustion is finished, the substance is pul- 
 verized and sifted whilst yet hot, and kept in well-stopped 
 jars, as it rapidly absorbs moisture from the atmosphere. 
 
 Black flux is much used in lead and copper assays ; but as 
 it boils up greatly at the commencement of the operation, the 
 crucible must not be more than two-thirds full. 
 
 It can be readily imagined that, as it fuses and reduces at 
 the same time, the relative proportions of alkaline, carbonate, 
 and charcoal ought to vary according to the nature of the 
 substance acted upon ; and it is often expedient to employ the 
 greatest possible proportion of alkali to obtain the largest 
 yield of metal. Black flux may be obtained richer in carbon 
 by mixing 1 part of nitre with 2 J or three parts of argol. 
 
 Common black flux contains 5 per cent, of charcoal. The 
 flux prepared with 2J of tartar or argol to 1 of nitre, con- 
 tains 8 per cent., and that with 3 contains 12 per cent, of 
 charcoal. 
 
 Black flux can be replaced by anhydrous or dry carbonate 
 of soda mixed with some reducing agent. When charcoal is 
 employed it must be reduced to a very fine powder ; in fact, 
 it ought to be levigated. 
 
 The three following fluxes are very useful : 
 
 Carbonate of Soda . . 94 88 816 
 
 Charcoal . . . . 6 12 184 
 
 The second is very nearly equivalent to sodium and car- 
 bonic acid, and the third to sodium and carbonic oxide ; but 
 it must be observed, that whatever precautions be taken, 
 these mixtures never become so liquid as black flux, because 
 the charcoal tends very much to separate and rise to the sur- 
 face. 
 
208 FLUXES : — POTASSA SALTS. 
 
 Instead of charcoal, it is preferable to use sugar or starch 
 to make a flux equivalent to black flux with carbonate of soda; 
 the mixture must be made most intimately. 
 
 Cream of tartar, carbonized by a semi-combustion until it 
 is reduced to half its weight, is a very good substitute for 
 black flux : it contains about 10 per cent, of charcoal. 
 
 Argol^ Cream of Tartar^ Bitartrate of Potassa. — When bi- 
 tartrate of potassa is heated in a covered crucible, a rapid 
 decomposition takes place, accompanied by a disengagement 
 of inflammable gases ; the substance agglomerates, but with- 
 out fusing or boiling up. The residue is black, blebby, and 
 friable, and contains 15 per cent, of carbon when produced 
 from rough tartar or argol, and 7 per cent, from cream of 
 tartar. 
 
 These reagents produce the same effects as black flux, and 
 possess more reducing power, because they contain more com- 
 bustible matter; but this is an inconvenience, because the 
 excess prevents their entering into full fusion when the 
 substance to be assayed requires but a small proportion of a 
 reducing agent. They can be used with success in assays re- 
 quiring much carbonaceous matter. 
 
 Bisulphate of Potassa is a convenient flux for several 
 minerals, such as for those highly aluminous {Hose), for chromic 
 and other similar ores (Booth). 
 
 Salt of Sorrel, Binoxalate of Potassa, when heated is de- 
 composed. It decrepitates feebly, and during its decomposi- 
 tion is covered with a blue flame ; it at first softens, and when 
 fully fused, is wholly converted into carbonate. When the 
 oxalate is very pure, the resulting carbonate is perfectly white 
 and free from charcoal ; but very often it is spotted with 
 blackish marks. It has no very great reducing power. 
 
 Cyanide of Potassium acts powerfully both as a reducing 
 and desulphurizing reagent, and is a very useful flux in small 
 assays. According to Liebig it has the advantage over the 
 potassa salts with vegetable acids, of not carbonizing the 
 metal, for the salt changes at the expense of the metallic 
 oxide into cyanate of potassa. If the metallic oxide predomi- 
 nates, the rest will be reduced by the cyanic acid without 
 separation of carbon. 
 
 White, or Mottled Soap is a compound of soda with a fat 
 acid. When heated in close vessels it fuses, boiling up con- 
 siderably, and during its decomposition gives off smoke and 
 
METALLIC FLUXES : — LITHARGE ; — GLASS. 209 
 
 combustible gases, and leaves a residue composed of car- 
 bonate of soda with about 5 per cent, of charcoal. Of all 
 reducing agents soap absorbs the greatest quantity of oxygen, 
 and as the residue of its decomposition by heat affords but 
 little charcoal, it has the property of forming very fluid slags. 
 Nevertheless, it is rarely employed because certain inconve- 
 niences outweigh its advantages. These inconveniences are, 
 its bubbling up and its extreme lightness. It also requires to 
 be rasped, in order to mix it perfectly with the substances it 
 is to decompose, and it then occupies a very large volume, 
 and requires correspondingly large crucibles. There are 
 nevertheless cases where it may be used with advantage by 
 mixing it with other fluxes. 
 
 All those fluxes containing alkaline and carbonaceous sub- 
 stances are reducing and desulphurizing, besides acting as 
 fluxes, properly so called ; they also produce another efi'ect 
 w^hich it is useful to know, viz : they have the property of in- 
 troducing a certain quantity of potassium or sodium into the 
 reduced metal. This was first pointed out by M. Vauquelin.* 
 He found that when oxide of antimony, bismuth, or lead was 
 fused with an excess of tartar, the metals obtained possessed 
 some peculiar characters, which they owed to the presence of 
 several per cent, of potassium. 
 
 Metallic Fluxes — Litharge and Ceruse, — These bodies 
 always act as fluxes, but at the same time often produce an 
 alloy with the metal contained in the ore to be assayed. 
 Ceruse produces the same fluxing efiect as litharge. The 
 litharge is the better flux, and is very useful in a great number 
 of assays. 
 
 It fuses readily with the oxides of iron, copper, bismuth, 
 antimony and arsenic, sulphate of lead and the silicates, in 
 the proportion of 2 to 5 parts of litharge to 1 part of the 
 substance to be fluxed ; other oxides require a larger amount 
 of litharge. Its action is that of promoting fusion, reducing 
 an oxide and desulphurizing a sulphuret. 
 
 Glass of Lead, Silicate of Lead. — The silicates of lead are 
 preferable to litharge in the treatment of substances contain- 
 ing no silica, or which contain earths or oxides not capable of 
 forming a compound with oxide of lead, excepting by the aid 
 of silica. It may be made by fusing 1 part of sand with 4 
 
 * Annales des Mines. 
 
210 FLUXING : — CALCINATION. 
 
 parts of litharge ; if required more fusible, a larger proportion 
 of litharge must be added. 
 
 Borates of Lead. — The borates of lead are better fluxes 
 than the silicates when the substance to be assayed contains 
 free earths ; but in order to prevent them swelling up much 
 when fused, they must contain an excess of oxide of lead. 
 The borate of lead containing .9056 of oxide of lead and .0944 
 of boracic acid, is very good. Instead of borate of lead, a 
 mixture of fused borax and litharge may be employed ; it is 
 equally serviceable. 
 
 Sulphate of Lead is decomposed by all silicious matters 
 and by lime, so that when these substances are present litharge 
 is produced, which fluxes them. 
 
 Oxide of Copper is rarely used as a flux for oxidated mat- 
 ters, but is sometimes employed in the assays of gold and zinc 
 to form an alloy with those metals. In this case a reducing 
 flux must be mixed with the oxide. Metallic copper may be 
 used, but is not so useful, as it cannot be so intimately mixed 
 with the assay. 
 
 Oxides of Iron are good fluxes for the silicates. They are, 
 however, rarely employed for that purpose ; they are more 
 often used to introduce metallic iron into an alloy to collect 
 an infusible, or nearly infusible metal, by alloying it with 
 iron, such as manganese, tungsten, or molybdenum. 
 
 Calcination. — The separation (in a dry way) of volatile 
 from fixed matter, by heat, is termed calcination. The pro- 
 cess is applicable 
 
 To the expulsion of water from salts, minerals, coals and 
 other substances. 
 
 " " " carbonic acid from certain carbonates. ^ 
 
 " " " arsenic and sulphur from cobalt, nickel 
 
 and other sulphuretted compounds. 
 
 " " " bituminous matter from coals, and cer- 
 
 tain minerals and ores. 
 To the ignition of quartz and silicious minerals to promote 
 
 their disintegration (p. 77). 
 For the purpose of expelling the combined water of argilla- 
 ceous minerals, and of thus rendering them more obstinate 
 
 to the solvent action of acids and reagents. 
 
 If the substance under process is organic, its calcination in 
 a close vessel by a medium heat usually effects only partial 
 decomposition, the gaseous matter generated escaping through 
 interstices and the fixed components remaining with a portion 
 
COKING. — INCINERATION. — ROASTING. 211 
 
 of unaltered carbon. Performed in this manner, the process 
 takes the name of coking, familiar instances of which are the 
 formation of coke by distilling coal in closed retorts, the 
 manufacture of charcoal from wood, and of bone black from 
 bones. 
 
 By increasing the temperature and admitting the air, the 
 whole of the alterable and volatile matter is expelled, the 
 fixed matter remaining as ashes. The process is then styled 
 incineration, and in this way the coke, charcoal and ivory 
 black, obtained as above directed, may be entirely reduced 
 to their incombustible portions or ashes. 
 
 Calcination is effected in platinum spoons or crucibles, in 
 delicate experiments, over a spirit lamp ; but in large opera- 
 tions a furnace is required, and the containing vessels are 
 crucibles of either metal or earthenware, according to the 
 nature of the substance to be heated, though the latter are 
 often unsuitable for temperatures above a red heat. 
 
 When the operation is finished, the crucible should be taken 
 from the fire and allowed to cool gradually. The cover is 
 then to be lifted oif and the contents taken out with a spatula, 
 and the portions adhering to the sides removed with a feather. 
 
 If the substance undergoing calcination is fusible, it is 
 necessary when quantities are to be ascertained, to weigh both 
 the crucible and contents before ignition, so that the amount 
 of volatile matter driven off may be expressed by the weight 
 lost in heating. Water alone or acidulated, with the aid of 
 heat generally removes the calcined matter from the crucible. 
 
 A body decrepitating by heat should be powdered before 
 being subjected to the process of calcination, and the tem- 
 perature should be raised slowly and gradually, otherwise 
 when the crucible is not covered, a loss may result from the 
 ejection of particles. 
 
 To avoid contact with the generated vapors or with the 
 atmosphere, which to some substances act as reducing agents, 
 the crucible should in such cases be covered, and if tightly 
 luted perforated with one or more small holes for the escape 
 of vapor. 
 
 Roasting (as the term is generally used) is a kind of cal- 
 cination to which many ores are submitted before their final 
 reduction to the metallic state, for the purpose of expelling 
 ingredients which would either delay that process or be in- 
 jurious to the metal when extracted. In this way water, 
 
212 ROASTING.— DEFLAGRATION. 
 
 carbonic acid, sulphur, selenium, arsenic, and sometimes other 
 substances, are driven off from the ores containing them. 
 The term is also applied to other processes, among the most 
 important of which is that of the exposure to heat and air by 
 which metals become altered in composition. Thus, copper 
 becomes oxidized, and antimony and arsenic acidified by 
 union with oxygen. 
 
 Roasting is always effected in broad, shallow open vessels, 
 so that the air may have free access ; and in order to promote 
 the absorption of oxygen or the escape of the volatile sab- 
 stance, the surface of the body to be heated should be in- 
 creased by previous pulverization, and it should ba constantly 
 stirred during the operation so as to present as many points 
 of contact as possible. The most suitable vessel is a baked 
 earthenware saucer or capsule placed in a muffle or upon the 
 bars of a calcining furnace. Sometimes a crucible is used, 
 and then the position of the vessel in the furnace should be 
 slightly inclined on one side. In either case the vessels 
 should be heated to dull redness previous to receiving their 
 charge. 
 
 That species of roasting termed deflagration is effected 
 by rapidly heating the substance to be oxidized, together 
 with some additional body as an oxidizing agent, as a 
 nitrate or chlorate for instance. The powdered mixture is 
 added portionwise to the crucible previously heated, and 
 maintained at redness during the operation. The vivid and 
 sudden combustion which ensues modifies the composition of 
 the original substance and increases its amount of oxygen at 
 the expense of the addendum. Thus for instance, sulphuret 
 of arsenic is deflagrated with nitre to produce arseniate of 
 potassa, titanium and certain other metals to be transformed 
 into oxides. 
 
 Deflagration is also used as a means of detecting the pre- 
 sence of nitric or chloric acids. For this purpose the sus- 
 pected substance is to be heated with cyanide of potassium, 
 in a small platinum spoon. If deflagration ensues it is a test 
 of the presence of one of them, or a compound of one of them. 
 
 The crucibles may be of clay or metal according to the 
 nature of the substance to be heated. The roasting of sub- 
 stances for the expulsion of organic matter may be effected 
 in platinum vessels, provided the heat is not carried suffi- 
 ciently high to produce fusion of the substance being roasted. 
 
DECREPITATION. — REDUCTION. 218 
 
 The heat must, at first, be very gradually applied, and at 
 no time be made great enough to fuse or agglutinate the ma- 
 terial, otherwise the process will have to be suspended in order 
 to repulverize the matter. Proper care at the commencement 
 will obviate the necessity of this additional trouble. When 
 the heat has been cautiously raised to redness and all liability 
 of fusion is over, the fire may be urged to the production of 
 a yellowish red or even white heat, so that the expulsion of 
 volatile matter may be complete. 
 
 Roasting operations which disengage deleterious or disa- 
 greeable fumes should be carried on in the open air or under a 
 hood, and when the volatile matters are valuable they may 
 be condensed as directed in distillation and sublimation. 
 
 Decrepitation, which frequently occurs sftid occasions loss 
 by ejections of particles of the mixture, is owing to the sudden 
 vaporization of the water of crystallization, which in finding 
 vent scatters the confining substance with a crackling noise. 
 To prevent this loss, the crucible should be loosely covered 
 until decrepitation ceases. 
 
 Reduction. — This operation is employed for the separation 
 of metallic bases from any bodies with which they are com- 
 bined ; but is generally confined to the extraction from an 
 oxide — that being the kind of combination most commonly 
 met with. The combined action of heat and certain reagents 
 is required to efi'ect this result, the temperature varying with 
 the nature of the substance to be reduced. 
 
 The most usual reducing agents are charcoal and hydrogen 
 gas. Tallow, oil and resin are sometimes used, but being 
 easily decomposed they are dissipated before entire reduction 
 has occurred. Sugar and starch are also occasionally em- 
 ployed. We shall, however, confine our remarks to the two 
 principal articles. 
 
 Reduction hy Qharcoal. — Charcoal is used for this purpose 
 in two ways, either in powder and directly mixed with the 
 substance, or as a lining coat to the crucible in which the 
 reduction is accomplished. The first mode is objectionable, 
 because the excess of coal which is required to be used inter- 
 feres with the agglomeration of the particles of reduced metal. 
 Whenever it is adopted, the quantity of coal dust to be added, 
 which must be sufficient to transform all the oxygen of the 
 oxide into carbonic acid, can be determined by calculation. 
 This amount is then mixed thoroughly with the oxide pre- 
 
214 REDUCTION BY HYDROGEN. 
 
 viously powdered, and is transferred to a crucible, taking care 
 to place the charge in the centre and to cover the contents 
 with a layer of the dust. The whole is then to be subjected 
 to the heat of a furnace, assisted if necessary, by a blast. 
 The reduction in this way, the most convenient for large 
 quantities, is rapid and complete, but the metallic residue is 
 often mixed with coal dust. 
 
 In general the mere contact of carbon is sufficient to eifect 
 reduction, and consequently the inconvenience of the above 
 plan may be avoided by the use of a brasque or crucible lined 
 interiorly with charcoal. An earthen crucible is very readily 
 brasqued as follows : — A mixture of three parts of charcoal 
 dust, and two parts of powdered clay, is mixed with water and 
 kneaded into a plastic dough. The bottom of the crucible is 
 then covered with this dough, and a wooden cylindrical core 
 of diameter equal to that required for the cavity, is inserted 
 in the centre and surrounded with more of the same dough, 
 which is compressed with the fingers at each addition so as to 
 make the whole as compact as possible. The core is then to 
 be carefully withdrawn, and the crucible placed aside to dry. 
 A platinum crucible, which is as applicable as clay for certain 
 operations, can be brasqued in the same way. Some operators 
 use the coal dust without clay, and moisten it with water or 
 oil. The crucibles should be free from external fissures to 
 prevent access of air, and must always be covered when 
 heated. The reduction by this plan is slower than by the 
 first mode, and requires a higher temperature, but the metal 
 as procured is cleaner. 
 
 The powdered oxide is placed in the cavity in sufficient 
 quantity to fill it, then compressed with the fingers and co- 
 vered with a layer of coal dust. The cover being luted upon 
 the crucible the whole is to be heated in a blast furnace. The 
 reduction proceeds from the surface, that part of the oxide next 
 to the charcoal being first acted upon. The time required de- 
 pends upon the nature of the oxide, the degree of tempera- 
 ture and the quantity under process : sometimes, particularly 
 when the metals are very fusible, the reduced particles collect 
 in a clean lump at the bottom of the crucible, and are easily 
 removable when cold, with the finger or spatula. Others 
 again, more refractory, form a very friable lump of metallic 
 powder. 
 
 Reduction hy Hydrogen. — This mode, which is much used in 
 
REDUCTION APPARATUS. 
 
 215 
 
 analyses, consists in passing a current of hydrogen gas over the 
 metallic oxides heated to redness in a glass, or better, por- 
 celain tube, and is equally applicable to some chlorides and 
 other compounds. The arrangement of the requsite appa- 
 ratus is shown in Fig. 166. ^ is a flask for the disengage- 
 
 Fig. 166. 
 
 ment of hydrogen gas, by the action of dilute sulphuric acid 
 upon zinc, the funneled tube a being for the ingress of the 
 acid. The disengagement tube h is bent at right angles and 
 bulbed midway in its horizontal arm. The bulb is to be fur- 
 nished with a plug of raw cotton for the condensation and 
 retention of any aqueous vapor that may pass over. This 
 tube is joined hermetically to another short tube c by means 
 of an India rubber connection.* The connecting tube is made 
 
 • The use of India rubber as a material for forming flexible joints is one of 
 the most important aids in chemical manipulation, as is shown by a reference 
 to many pieces of apparatus. Its property of readily uniting at freshly cut sur- 
 faces, its flexibility, its ready and close adhesion to surfaces, and power of resist- 
 ing the action of corrosive vapors except those of chlorine, sulphuric and nitric 
 acids and a few others, render it peculiarly excellent for many mechanical purposes 
 of the laboratory. Tubes of any shape and size, according to the form and dimen- 
 sions of the parts of apparatus to be connected, are to be fashioned out of it with 
 almost equal flicility. For the transmission of corrosive vapors or gases they should, 
 have an outer layer, the seam in which must be directly opposite to that in the tube 
 which it invests, so as to ensure perfect tightness. Prof. Booth uses the India 
 rubber pipe, made by Goodyear as conduits for steam in boiling corrosive liquids 
 
216 FLEXIBLE TUBES. — GAS BAGS. 
 
 of sheet caoutcliouc about one-twelfth of an inch in thickness. 
 
 A piece of the required length of 
 ^ig- 16'''- the tube and twice the intended 
 
 width is cut out and wrapped 
 around a cylindrical glass rod, c?, 
 Fig. 167, of diameter very nearly 
 as great as that for the tube to 
 be formed. The ends are then 
 brought closely together by com- 
 pression between the thumb and 
 fingers as at a, and the excess 
 removed, close to the surface of the rod, with a pair of 
 clean sharp scissors. The freshly cut edges being further 
 pinched together throughout the length of the tube, form a 
 close, air-tight, scarcely perceptible joint. The rod is then 
 to be withdrawn and the tube thus formed carefully drawn over 
 the end of one of the glass tubes to be connected, so as to form 
 an extension for the reception of the end of the other. The two 
 ends should approach each other almost to contact, a minute 
 interval being necessary to afford the necessary flexibility. 
 This junction pipe is fastened to the surface of the tube by 
 fine twine wrapped or tied around each of its ends, as shown 
 at X, Fig. 166. 
 
 The gas bottle thus fitted is connected, by means of a per- 
 forated cork with the drying tube c?, filled with lumps of dried 
 chloride of calcium. At the opposite end of the drying tube 
 
 by that agent, and gives it consistence with flexible lead pipe, which he covers 
 externally and internally. A better frame work would be a spiral coil of wire. 
 The tubing made of canvas imbued with caoutchouc is less durable, and does 
 not admit of such general application. 
 
 Before forming the tube above mentioned, it is better to warm the caoutchouc, 
 by which its flexibility is increased and its cut surface made to adhere more rea- 
 dily and closely. The scissors cut more freely when previously moistened. 
 These flexible joints not only relieve the apparatus of stifiness and consequent 
 liability to fracture, but enable the operator to adjust it more rapidly and satis- 
 factorily than he could possibly do without them. A little practice upon shreds 
 will give great proficiency in the art of forming India rubber tubes and joints. 
 
 India rubber for this purpose is now made by Goodyear, New York, who sells 
 it in sheets of various sizes. Gas bags are also made of caoutchouc. The larger 
 sized, pp. 171, 173, are to be procured from the manufacturer. Smaller ones, 
 for nice purposes, may be readily made from the rubber bottles of the shops. 
 One of uniform thickness, and as free as possible from indentations and imper- 
 fections, is softened in boiling water or by exposure for several hours to the 
 vapor of ether, and then adjusted upon a stop-cock with a syringe attached. The 
 air is then to be injected slowly so that the expansion of the bag may be gradual 
 and uniform throughout all its pans. 
 
REDUCTION BY HYDROGEN. 217 
 
 e, is another tube with a bulb blown in its centre for the recep- 
 tion of the substance to be reduced, and in which it is heated 
 by the flame of a spirit lamp. This tube, like the other, is 
 annexed by elastic joints to the short tube connected with 
 the desiccating tube through a perforated cork. 
 
 This plan, first proposed by Berzelius, was used by him in 
 the synthesis of water, binoxide of copper being the substance 
 employed to abstract the hydrogen, its oxygen forming water 
 therewith. 
 
 Hydrogen is a powerful reducing agent, and leaves the 
 metal absolutely pure. At a red or white heat, its action will 
 reduce the oxides of lead, bismuth, copper, antimony, zinc, 
 iron, cobalt, nickel, tungsten, molybdenum, and uranium. 
 
 The heat should not be applied to the bulb until it is entirely 
 freed from air, which may be done by allowing the hydrogen to 
 pass over some minutes previously. A disregard of this pre- 
 caution may cause an explosion from the combustion of a 
 mixture of hydrogen and atmospheric air. 
 
 The above apparatus answers very well for decomposing 
 metallic sulphurets by chlorine. It is also applicable for 
 heating solids in gases, and serves for the preparation of 
 chloride of sulphur, of phosphorus, and of many other vola- 
 tile chlorides. For this purpose it is only necessary to replace 
 the flask A by other suitable generating vessels, and the 
 extreme end of the exit tube by a tubulated retort with its 
 beak bent downwards and leading into the recipient, kept 
 cool by a frigorific mixture. 
 
 The tubes for these purposes must be of hard glass and 
 entirely free from lead, and not exceeding a third of an inch 
 in width. The bulbs should be of IJ inch diameter. The 
 chlorcalcium tube may be three-fourths of an inch wide. 
 
 There are other modes of reduction of less general applica- 
 tion, however, than the preceding. Metals may be precipi- 
 tated in a free state, in some instances, from solutions, by 
 presenting bodies for which their oxygen has a stronger affi- 
 nity, thus, for example, protosulphate of iron precipitates 
 metallic gold; phosphorous acid mercury; and formic acid or 
 formate of soda, both of these metals, and also silver and 
 platinum, if the liquids containing them in solution are boiled. 
 So also one metal may reduce another if the affinity of the 
 first for oxygen is greater than that of the last. Thus me- 
 15 
 
218 REDUCTION BY CARBONIC OXIDE. 
 
 tallic copper throws down mercury, silver, and arsenic from 
 their solutions, and iron precipitates copper. 
 
 Metals are also reduced by galvanic action, practical illus- 
 trations of which are seen in the galvanoplastic art. All 
 oxides which resist the combinedi action of heat and charcoal 
 or hydrogen, are reduced by the^agency of galvanism. 
 
 Reduction by Carbonic Oxide. — Another convenient agent 
 of reduction, employed in the same manner as hydrogen, is 
 carbonic oxide, made on a small scale by the action of oil of 
 vitriol on oxalic acid, and separation of the carbonic acid 
 produced at the same time, by milk of lime. It readily re- 
 duces the metallic oxides of nickel, iron, zinc, that of lead at 
 a very low temperature, and that of copper" below a red heat. 
 For heating in manufacturing processes, it is made by regu- 
 lating the admission of air to a deep bed of ignited anthracite 
 or other coals, and driving a blast of air horizontally through 
 the gas as it issues from the fire, all other access of air being 
 prevented. It has in this manner been applied to re-heating 
 and puddling furnaces. Carbonic oxide is doubtless the great 
 reducing agent in large metallurgic operations. 
 
 lioasting and Heduction in Tubes. — In very delicate ex- 
 periments, and particularly when the volatile matter expelled 
 by the heat is to be collected for examinatio|ji, roasting and 
 reduction are effected in small glass tubes* closed at one end. 
 
 * Porcelain and Metallic Tubes. — For the reduction of some oxides by contact 
 with gases at furnace temperature, for the decomposition of certain organic mat- 
 ters, such as oils, &c., and for efF^cting many combinations of gases with soUds, 
 the glass tubes are replaced by those of porcelain, iron, or platinum. 
 
 Porcelain tubing should be selected with care. It should be straight, perfectly 
 cylindrical, Iree from defects, glazed internally and as thin as possible. These 
 tubes are adjusted in manner as directed for those of glass, and heated over the 
 furnace, Fig. 103, but as they are not refractory, care must be taken in heating 
 them. It is advisable to give them an exterior coaling of fire lute and then dry 
 them. Tlie fire should be ignited and all moisture expelled from the charcoal 
 before they are placed in the furnace, otherwise their fracture may result. It is 
 indispensable, too, that the heat shall be carefully managed, and after the com- 
 l)letion of the process the tube must not be removed from the furnace until it 
 has entirely but gradually cooled. 
 
 Iron tubes are used for the decomposition of water, potassa and for other 
 operations to which those of glass and porcelain are not adapted by reason of 
 inability to withstand high heat. Gas tubing is the most economical, and can 
 
ROASTING AND REDUCTION IN TUBES. 
 
 Fig. 168. 
 
 219 
 
 3 
 
 3 * 
 
 O 5 
 
 The glass must be white, difficultly fusible, and free from lead. 
 The substance is placed in the lower or closed end of the tube, 
 
 be had of all lengths and diameters. These also should be covered exteriorly 
 with luting so as to prevent the oxidation of the iron by the fire. 
 
 Metallic tubes of small size may be heated over the furnace, Fig. 103, but 
 those of larger dimensions require the use of the furnace, Fig. 88. The circular 
 openings x a;, in each side, are especially for the passage of a tube. The grate 
 should be elevated so that the fire may entirely surround it. 
 
 Metallic tubes are adjusted to generating and other apparatus by means of 
 metallic couplings, gallows screws, or, in some cases, by fire lute. This latter 
 does not make a secure or tight joint, and is only used in the absence of more 
 convenient means. The ends of the tube should project far enough beyond the 
 sides of the furnace to allow their refrigeration when necessary. The gas may 
 be introduced directly from the generating vessel, or from a caoutchouc bag, or 
 gasometer, merely by adjusting the end of the tube with the mouth or outlet by 
 a suitable coupling. The resultant product may, in like manner, be collected by 
 similar adaptations to the other end. 
 
 Fragments of flint or coils of iron or of platinum wire, placed within the tube, 
 increase the points of contact of the contained matter and greatly promote its 
 heating. 
 
 As short tubes are occasionally used for effecting the combination of substances 
 alterable by exposure in a hot state, they should, for such purposes, be fitted at 
 the ends with screw plugs to prevent access of air. 
 
 Platinum tubes are only used on rare occasions for particular purposes to 
 which those of glass, porcelain, or iron are inapplicable. 
 
220 ROASTING AND REDUCTION IN TUBES. 
 
 whicli is then inclined and heated over the spirit lamp, as shown 
 in Fig. 174. In this way sulphur and arsenic may he sublimed 
 from certain of their compounds, and mercury from less vola- 
 tile metals. By leaving the tube open at both ends so as to 
 allow free access of air, many volatile bodies are oxidized and 
 collect, on congelation, in the upper part of the vessel. Those 
 tubes with a bulb blown at their lower end, as shown at 1, 5, 
 in Fig. 168, are most applicable for decrepitating substances. 
 
 Below are the several forms of tubes used for the reduction 
 of metals, and particularly the separation of arsenic and mer- 
 cury from more fixed matter. Any of these forms, or even a 
 small test tube 4 will answer. Berzelius prefers the shape 
 of 1 ; Rose that of 2 ; Liebig that of 3 ; and Clarke that of 5. 
 
 The letters a b e in 2, and b in 3, indicate the position of 
 the substance to be roasted together with its reducing agent, 
 and d and a in 2 and 3, the rings of condensed volatile 
 matter sublimed by the heat. Berzelius and Rose's, and 
 Liebig's tubes are three inches in length; Clark's two inches. 
 Their diameters vary from -jJgth to a Jth of an inch according 
 to the amount of substance to be heated. 
 
 CHAPTER XVI. 
 
 CUPELLATION. 
 
 Gold and silver are assayed by the agency of heat and 
 litharge in shallow, slightly conical crucibles. Fig. 169, called 
 cupels. This process aifords these metals free from any de- 
 basement with which they may be contaminated; for, when 
 
 Fig. 1G9. 
 
 the alloy is heated together with litharge, all but the precious 
 metals are oxidized; and the oxides thus formed, together 
 with the semi-vitrous litharge, are absorbed by the cupel 
 whilst the nobler metal remains as a button of absolute 
 purity. 
 
CUPELLATION : — CUPELS. 221 
 
 Cupels. — Thej are generally made of bone ash, because 
 that material fulfils better than any other the necessary require- 
 ments. It is resistant to the action of the fused oxides of lead 
 and bismuth, and by its porosity facilitates the penetration of 
 the oxides, and at the same time is, when made into shape, 
 strong enough to bear handling without fracture. The cupels 
 used at the mint in this city, are made in a matrix of If 
 inches diameter. The semi-circular cavity is two-fifths of an 
 inch deep in the centre. This size, however, can be varied and 
 they may be made smaller or larger according to the quantity 
 of matter to be operated upon. Their mode of manufacture 
 is as follows : — Take bones or bone black and calcine them in 
 an open crucible until the expulsion of all animal and carbo- 
 naceous matter, which is known by the residue assuming a 
 whitish appearance. Empty the cooled contents of the cru- 
 cible into clean water, and give it repeated washings in fresh 
 w^aters to remove all soluble matter ; filter and dry. The dried 
 matter is pure phosphate of lime with a minute portion of 
 partially decomposed carbonate. 
 
 Take the powder, calcined and purified as directed above, 
 and make it into a paste with water or preferably with beer 
 (Mitchell), in the proportion of 4 lbs. of bone-ash to half a 
 pound of beer. The above mixture is just sufiiciently moist 
 to adhere strongly when well pressed, but not so moist as to 
 adhere to the finger or the mould employed to fashion the 
 cupels. The mould. Fig. 170, of polished iron, consists of 
 two pieces, one a ring having a conical opening; the 
 other, a pestle having a hemispherical end fitting the ^^s- ^''^' 
 larger opening of the ring. In order to mould the 
 cupels, proceed as follows: Fill the ring with the 
 composition, then place the pestle upon it and force 
 it down as much as possible; by this means, the 
 moistened bone-ash will become hardened, and take 
 the form of the pestle ; the latter must then be forced 
 as much as possible, by repeated blows from a ham- 
 mer, until quite home. It is then to be turned lightly 
 round, so as to smooth the inner surface of the cupel, and 
 withdrawn; the cupel is removed from the mould by a gentle 
 pressure on the narrowest end. When in this state, the cupel 
 must be dried gently by a stove; and lastly, ignited in a 
 mufl[le, to expel all moisture. It is then ready for use. 
 
 There are two or three points to attend to in manufactur- 
 
222 PROCESS OF cupellation: — muffles. 
 
 ing the best cupels. Firstly, the powdered bone-ash must be 
 of a certain degree of fineness ; secondly, the paste must be 
 neither too soft nor too dry; and thirdly, the pressure must 
 be made with a certain degree of force. A coarse powder, 
 only slightly moistened and compressed, furnishes cupels 
 which are very porous, and break on the least pressure, 
 and which allow small globules of metal to enter into their 
 pores — the most serious inconvenience of all. 
 
 When, on the contrary, the powder is very fine, the paste 
 very moist and compressed very strongly, the cupels have 
 much solidity, and are not very porous, the fine metal cannot 
 penetrate them, and the operation proceeds very slowly; 
 besides, the assay is likely to become dulled and incapable of 
 proceeding without a much higher degree of temperature being 
 employed. — {Bertliier.) 
 
 The Process of Cupellation. — In order to protect the cupel 
 from contact with the fire, and at the same time allow a 
 free access of the air, it is when being heated placed in a 
 muffle. The muffle is a refractory vessel of baked fire clay. 
 Fig. 171, arched above, flat bottomed, 
 Fig. 171. g^jj(j pierced near its base with small 
 
 lateral openings for the passage of the 
 heat. Excepting these apertures, and 
 that at the front for the introduction 
 of the cupels and inspection of the pro- 
 cess, the muffle is entirely closed. Its dimensions depend upon 
 the size of the cupel and of the furnace in which it is to be 
 heated. 
 
 Its position in the furnace (Fig. 98, and i). Fig. 101), must 
 be exactly level, and to protect it from the corrosive effects 
 of volatilized oxides, it may be payed over with a thin paste 
 of bone ashes. The muffle being properly arranged in the 
 furnace, and held firmly in its place by lute, the cupels are 
 
 then introduced and the fuel (char- 
 Fig. 172. coal) ignited. The lead must be 
 
 perfectly pure. It can be reduced, 
 
 II T_J for this purpose, from refined 
 
 litharge. "When the cupels have 
 j,.^ j_2 been exposed for half an hour, and 
 
 have become white by heat, the 
 lead is put into them by means of 
 the tongs, Fig. 172, and as soon 
 
CUPELLATION IN TAYLOR'S MUFFLE. 223 
 
 as this becomes thoroughly red and circulating, as it is called, 
 the metal to be assayed, wrapped in a small piece of paper, 
 is added, and the fire kept up strongly until the metal enters 
 the lead and circulates well, when the heat may be slightly 
 diminished, and so regulated that the assay shall appear con- 
 vex and ardent, while the cupel is less red — that the undula- 
 tions shall circulate in all directions, and that the middle of 
 the metal shall appear smooth, surrounded with a small circle 
 of litharge, which is being continually absorbed by the cupel. 
 This treatment must be continued until the metal becomes 
 bright and shining, or is said to Higlden;' after which cer- 
 tain prismatic colors, or rainbow hues, suddenly flash across 
 the globules, and undulate and cross each other, and the latter 
 metal soon after appears very brilliant and clear, and at length 
 becomes fixed and solid. This is called the 'brightening^'' 
 and shows that the separation is ended. In conducting this 
 process, all the materials used must be accurately weighed, 
 especially the weight of the alloy before cupellation, and the 
 resulting button of pure metal. The difference gives the 
 quantity of alloy." 
 
 When the operation is completed, the cupel is to be with- 
 drawn from the fire and allowed to cool, and the metallic 
 button then removed with the pincers. If the assay is a good 
 one, it will detach easily. The button should be round and 
 brilliant upon its upper surface, but rough and striated at the 
 bottom. If its surface is dull and flat, too much heat has 
 been employed; on the contrary, when it is spongy, adheres 
 tenaciously to the cupel, and contains scales of litharge, there 
 has been a deficiency of heat, and the fire must be again urged 
 and the flowing of the metal promoted, by adding to the cupel 
 a little powdered charcoal. Complete fusion is indispensable 
 to the success of the operation. If too much lead has been 
 added, the cupel is allowed to cool, the button carefully sepa- 
 rated so as to be free from adherent particles of ash, and 
 transferred to a fresh cupel and the process continued. In 
 experienced hands, the pneumatic blast, p. 169, may be made 
 to replace the furnace in the process of cupellation. 
 
 Cupellation in Taylor s Muffle. — Mr. T. Taylor {Memoirs 
 of Chem. Soc, vol. iii. p. 316), claims for his new form of 
 muflfle the following advantages: — "1st. Crucibles may be 
 maintained at a much higher temperature than can be readily 
 obtained when the ordinary muflSe is used, while the degree 
 
224 CUPELLATION IN TAYLOR'S MUFFLE. 
 
 of heat and the quantity of air admitted may be regulated 
 with the greatest nicety. 2d. Owing to the greater draught 
 of air, the oxidation of the lead (in the process of cupellation) 
 is more quickly effected; and lastly, by looking through an 
 opening in the furnace cover, the operation may be watched 
 from first to last. 
 
 ''Two black lead crucibles of the same size are ground flat, 
 so that when applied one to the other they may stand steady. 
 An oblong or semicircular notch is cut out of the mouth of 
 one of the crucibles, and a hole is also drilled through its bot- 
 tom. This crucible, when placed on the top of the other, 
 constitutes the muffle, and of course resembles in shape a 
 skittle. To cupel with this apparatus, the lower crucible is 
 nearly filled with clean sand, set upon the bars of the grate 
 in the centre of the furnace and brought to a low red heat. 
 The cupel containing the lead of the alloy is then placed upon 
 the sand and immediately covered by the crucible, taking care 
 that the notch in its side shall be opposite to, and correspond 
 with, the furnace door; more fuel is added, during which it is 
 well to cover the hole in the top of the muffle with a crucible 
 lid in order to prevent the admission of dirt. When the muffle 
 has become throughout of a bright red heat the furnace door 
 is thrown open, and the ignited fuel gently moved aside so as 
 to permit a view of the side opening in the muffle. The cur- 
 rent of air which is thus established through the muffle in- 
 stantly causes rapid oxidation of the lead, and this may be 
 regulated at pleasure by closing the door more or less. If 
 from the fuel falling down, any difficulty should be experienced 
 in maintaining a free passage for the air, a portion of a por- 
 celain tube, or a gun-barrel, may be passed through the fur- 
 nace door to within an inch of the muffle ; but this proceeding 
 is generally rendered quite unnecessary, by taking care to 
 place some large pieces of coke immediately round the door 
 of the furnace." 
 
SUBLIMATION : — DISTILLATION. 225 
 
 CHAPTER XVII. 
 
 SUBLIMATION. — DISTILLATION. . 
 
 When simple or compound bodies which are either wholly 
 or in part capable of assuming the aeriform state are sub- 
 jected to heat, they or their most volatile constituents, upon 
 reaching the required temperature, rise in the form of vapor. 
 If these vapors, in their transit, are intercepted by a surface 
 of a lower temperature, they condense and take a solid or 
 liquid form, according to their nature. If the product is a 
 solid, it is termed sublimate^ and the process by which it is 
 obtained is sublimation; — if it is liquid or gas, it takes the 
 name of distillate^ and the operation which yields it that of 
 distillation. 
 
 Both of these processes are indispensably useful in chemis- 
 try, for they afford the facility of taking advantage of the 
 unequal volatility of bodies for their separation. 
 
 As instances of sublimation, w^e have calomel and corrosive 
 sublimate made by heating equivalent proportions of sulphate 
 of mercury and common salt; benzoic acid evolved from the 
 gum ; pure indigo from the commercial article, and camphor 
 from the crude material. Iodine is sublimed to free it from 
 impurities ; biniodide of mercury to convert it into crystals ; 
 naphthalin to free it from empyreumatic matter, and succinic 
 acid to separate water. 
 
 In like manner, multitudes of instances of the importance 
 of distillation in the everyday-processes of the chemist and the 
 manufacturer might be adduced. It is employed in the sepa- 
 ration and rectification of alcohol, the preparation of the 
 ethers, of many mineral and vegetable acids, and of a very 
 great number of other chemical products. 
 
 sublimation. 
 
 The implements of sublimation are manifold, and vary in 
 size and construction with the quantity of the substance to be 
 heated, the nature, degree of volatility and the afiinity of the 
 subliming body for the oxygen of the atmosphere. 
 
226 SUBLIMATION ; — IN TUBES. 
 
 There are certain rules to be observed in order to a suc- 
 cessful execution of the process ; but whatever the apparatus, 
 its arrangement and management must be such that there 
 shall be no diminution of the temperature of the vaporized 
 matter until it reaches the recipient in which it is to be refrige- 
 rated and condensed. 
 
 The covers of flat subliming vessels and the recipients or 
 condensing portions of those of other shapes, must invariably 
 be out of and above the fire and exposed to the cooling influ- 
 ence of air. When the sublimed particles are very volatile, it 
 will even be necessary to promote their condensation by 
 covering the recipient with rags, which are to be kept con- 
 stantly wet with cold water or some other refrigerant. 
 
 The usual mode of heating subliming vessels is by the sand 
 bath, but for some substances requiring a very high tempe- 
 rature for their volatilization, direct fire is necessary, and this 
 is applied with the lamp in small and nice operations, and in 
 larger ones with the furnace. 
 
 In order to prevent explosion, the small opening in the 
 top, at the centre of the refrigerant, must be only closed with 
 a plug of raw cotton and should be freed from obstruction by 
 occasional poking with a wire. When the escape of vapor 
 through this hole is rapid, the heat is too high and must be 
 diminished immediately. 
 
 After the completion of the operation, the apparatus must 
 be left to cool before it is opened or the recipient removed. 
 
 The necessary breaking of close vessels for the removal of 
 the contents, renders their use expensive ; whenever, therefore, 
 the nature of the substance will permit, an alembic with de- 
 tached head should be preferred. Such vessels are more 
 economical and easy of management, but generally require 
 that their joints be made impermeable by luting. 
 
 Sublimation in Tubes. — Sublimation is very available in 
 analyses for detecting the presence of minute quantities of 
 volatile metals, acids, and other substances, the implement 
 for the purpose being a small tube of such forms as is shown 
 in Figs. 168, 174. After the introduction of the substance, 
 previously powdered and dried, the tube is drawn out at its 
 open end to a fine orifice and the lower part heated gradually 
 over the flame of a spirit lamp (Fig. 174). The volatilized 
 portion will be condensed upon the sides of the upper and 
 cooler parts. By dividing the tube with a file, the sublimate 
 
SUBLIMATION IN FLASKS. 
 
 22T 
 
 Fig. 174. 
 
 Fig. 175. 
 
 can be exposed for microscopic examination or removed for 
 further assays under the 
 blow-pipe. The tubes for 
 sublimation may be from 4 
 to 8 inches in length and 
 from an eighth to half an 
 inch in diameter, according 
 to the quantity of the matter 
 to be sublimed and the re- 
 quired delicacy of the ope- 
 ration. 
 
 Berzelius uses a tube en- 
 tirely open at the upper end 
 
 for those sublimations in which there are two volatile products, 
 of which one is to be drawn off entirely in the form of gas by 
 the absorption of oxygen from the atmosphere and recognized 
 by its odor, and the other condensed in the upper part of the 
 tube, as for example a mixture of sulphur and selenium. 
 
 Faraday gives the form of a tube apparatus (Fig. 175) for 
 condensing heavy vapors or easily 
 fusible substances, as naphthaline, 
 iodine, &c. The bent tube 6 is of a 
 diameter only large enough to allow 
 its free passage over the subliming 
 tube a. The upper part of the middle 
 portion of the tube may be kept cool 
 by paper or cloth wrappers moistened with water in order to 
 promote the condensation of the sublimed matter. The heat 
 of the spirit lamp is sufficient for these small operations, and 
 the apparatus, as adjusted, may be properly maintained by 
 the upright clamp. Fig. 139. 
 
 Suhlimation in Flasks. — Florence or sweet oil flasks are 
 well adapted to purposes of sublimation on account of their 
 cheapness, uniformity of thickness, and power of resisting 
 high heats. Having received their charge they are to be 
 imbedded in a sand-bath to a depth above the level of the 
 contents, and heat is to be applied gradually until the proper 
 temperature is arrived at. The position of the flask should 
 be inclined so that its neck may lead directly into the reci- 
 pient, as shown in Fig. 176. In this manner considerable 
 quantities of matter may be operated upon even at high 
 temperatures, the glass bearing a red heat without injury. 
 
228 
 
 SUBLIMATION IN RETORTS, — CRUCIBLES. 
 
 Another mode of arranging a flask for this process is to con- 
 nect its neck in the manner of a hood, with a long bent tube 
 leading into the refrigerant and recipient, as shown in Fig. 
 
 Fig. 17G. 
 
 Fig. 177. 
 
 177. The inconvenience of this arrangement is the conden- 
 sation of the gaseous matter in the tube, the obstruction from 
 which may, without great care, cause the explosion of the 
 flask. 
 
 Flat bottomed flasks of thin German glass are sometimes 
 used, but they are more expensive than 
 oil flasks. Their position in the sand- 
 bath is upright and the flange around 
 their necks acts as a support for an in- 
 verted globular flask which serves as a 
 recipient. This arrangement, shown in 
 Fig. 178, is admirable for the sublima- 
 tion of substances, the volatile products 
 of which are so aggregated as to form 
 what are called flowers. 
 
 Sublimation in Retorts. — Glass retorts 
 are more expensive and less convenient 
 than flasks, except for the sublimation of 
 very volatile matters. They are arranged 
 as shown by Fig. 183, the beak, like the 
 neck of the flask, leading into a wide- 
 mouthed receiver. The alembic. Fig. 
 179, is frequently substituted for retorts 
 and is more convenient, as its head being 
 detached from the body allows the more easy removal of the 
 sublimed product. 
 
 Earthenware retorts with loose heads. Fig. 180, to be 
 fastened by pins and lute, are employed for sublimations re- 
 quiring high temperatures. 
 
 Sublimation in Crucibles. — The crucible for this purpose 
 
SUBLIMATION IN SHALLOW VESSELS. 229 
 
 may be of clay, platinum or iron, according to the nature of 
 the substance to be heated. It is first coated with a layer of 
 refractory clay paste and when this is dry, placed over a 
 furnace fire. An inverted crucible of the same size with a 
 small hole in its top, is then placed over as a recipient of the 
 
 Fig. 179. Fig. 180. 
 
 vaporized particles. The top crucible must be above and out 
 of the fire. When the operation is finished, and the ap- 
 paratus has cooled, the top may be removed and the crucible 
 emptied of its contents. 
 
 Sublimation in Shallow Vessels. — In the treatment of sub- 
 stances which sublime at a low heat, a plate or capsule resting 
 upon hot sand and surmounted by a glass funnel or a cone of 
 glazed paper, as a condenser and recipient, answers every 
 purpose, particularly in the sublimation of organic substances. 
 The top of the funnel and cone should be drawn out to a 
 small opening, and when the operation is finished the contents 
 of the refrigerant may be removed by a feather. 
 
 When iron capsules are used, as is often necessary in sub- 
 limations requiring high heat, they should be lined with a thick 
 dough of fire clay. Capsules with flat bottoms and of thick 
 sheet iron are most appropriate. Their dimensions may be 
 six inches in diameter and J to 1 inch in depth. The top 
 B must be of earthenware and 
 detached. The arrangement is Fig. 18 1. 
 
 shown in Fig. 181. This im- 
 plement requires a furnace heat. 
 The cover should be tightly ce- 
 mented with fire lute, and when 
 
 the whole has cooled, the cover may be taken off and the ad- 
 herent mass of sublimate removed with a spatula. The small 
 
230 
 
 HYDRO-SUBLIMATION. 
 
 cone c is to be kept over the hole in the cover to arrest any 
 escaping vapors. When it is necessary to probe the cavity it 
 may be temporarily removed with the tongs. A diaphragm 
 of porous white paper will arrest the passage of any empy- 
 reumatic matter and pass the sublimate free from color. 
 
 Two very concave watch glasses, placed the one upon the 
 other with their convex surfaces outward, make a very neat 
 subliming apparatus for minute quantities of rare matter. 
 
 Ures Apparatus. — This is a very convenient 
 
 Fig. 182. arrangement. Fig. 182, consisting of two metallic, 
 
 glass or porcelain vessels. The lower one is the 
 
 recipient of the matter to be sublimed, and the 
 
 upper a, which is the larger, covers the former, 
 
 and is to be filled with cold water to be replaced 
 
 as fast as it evaporates. When the process is 
 
 completed, the sublimed matter can be removed 
 
 from the exterior of the cover. 
 
 Henry 8 Apparatus for Hydro- Sublimation. — This arrange- 
 
 Fig. 183. 
 
 ment, shown in Fig. 183, has been proved by experience to 
 be practically useful. It is employed in manufacturing labo- 
 ratories for the sublimation of calomel, but is equally appli- 
 cable for other substances ; and by lessening the dimensions 
 of the several pieces, may be made very convenient for experi- 
 mental purposes. 
 
 It consists of a large globular glass vessel a, with a long, 
 straight neck, and two short, lateral tubulures of equal width. 
 
HENRY S APPARATUS FOR HYDRO-SUBLIMATION. 
 
 231 
 
 Por manufacturing purposes the globe must be of stone-ware, 
 and of two or more gallons capacity. In either case it rests 
 upon the ledge of a blue stone-ware cylinder A, containing 
 sufficient water to close the neck of the globe which dips 
 lightly into it. One of the tubulures receives the neck of the 
 retort 6, and the other that of the still, Fig. 13, which 
 furnishes the steam, or, what is better, the conduit pipe of 
 the generator. Fig. 10. The retort 5, of earthen-ware, or 
 iron, coated interiorly with fire clay, is for the evolution of 
 the calomel or sublimate in vapors. It is wholly enclosed in 
 the furnace, and its very short neck passes immediately from 
 it into the globe a, so as to prevent the condensation of the 
 sublimate in the neck and upper portion. The joints should 
 be tightly luted. The success of the operation depends 
 mainly upon a proper management of the fire and supply of 
 aqueous vapor. The heat should be just sufficient to drive 
 over the sublimate slowly, and the steam should be supplied 
 in large excess, and simultaneously with the appearance of 
 the vaporized solid. For this purpose the steam conduit must 
 be fitted with a cock for the regulation of the flow of its con- 
 tents of vapor. As soon as the sublimed molecules come in 
 contact with the aqueous vapor, they are condensed in the 
 globe a, and precipitate as powder (p. 84) into h. 
 
 By increasing the size of the globe a, threefold, diminish- 
 ing the orifice of its neck by means 
 of a small glass tube traversing a Fig. 184. 
 
 perforated cork, and by omitting the 
 tubulure on the other side, the steam 
 may be dispensed with for the sub- 
 limations of volatile solids into flowers. 
 The neck in this case must point up- 
 wards. 
 
 For experimental operations, a small 
 earthen-ware retort and glass globe 
 will answer every purpose. The steam 
 can be supplied from the copper wash- 
 ing bottle, Fig. 185, by substituting 
 for the spirting tube c?, a flexible leaden 
 pipe c, which is to be connected with 
 the neck of the flask by a coupling 
 
 screw a. The gas or spirit-lamp will furnish ample heat for 
 the generation of steam in this apparatus. 
 
232 
 
 STEAM SPRITZ. — DISTILLATION. 
 
 Fig. 185. Fig. 186. 
 
 <^3>^^ 
 
 DISTILLATION. 
 
 A process bj which substances are heated for the separa- 
 tion of a volatile from a more fixed portion. The apparatus 
 for the purpose consists of a close vessel in which the heating 
 takes place, a refrigerant for the condensation of volatilized 
 particles, and a recipient for the retention of the product ; 
 the two latter purposes being often, however, fulfilled bj the 
 same vessel. When this product condenses as a fluid, the 
 process takes the name of liquid distillation, and if as a gas, 
 of gaseous distillatio7i. The subjection of a body to very high 
 heat, for the purpose of decomposing it and receiving the 
 generated products, is called dry or destructive distillation. 
 In Sublimation, which may be styled solid distillation, the 
 volatilized matter is received and condensed in one vessel 
 without the necessity of an intermediate refrigerant. 
 
 The process of distillation is one of the most indispensable 
 in chemical investigation, as by its aid we can not only sepa- 
 rate liquids of diflerent volatility, but also collect new vola- 
 tile products which may result from the decomposition of sin- 
 gle or mixed^ubstances. As instances of its valuable use, we 
 can by its aid separate the essential oil and volatile constitu- 
 ents of plclfnts and of other materials, — recover alcohol, ether, 
 or any valuable volatile liquid, from solutions in which they 
 
 ^' 
 
distillation:— THE STILL. 
 
 233 
 
 are solvents, — refine a liquid from its fixed impurities, — free it 
 from fixed matter which it may have in solution, and, aided 
 by an absorbent material, remove any contained water. More- 
 over it allows the collection, either free or in solution, of gases 
 generated by chemical reaction. 
 
 The Still. — The still is the common implement used in 
 large operations of liquid distillation. It is generally made 
 of copper, and is tinned internally. A convenient form has 
 already been fully described at page 44. The figure below, 
 Fig. 187, exhibits another of handsomer appearance, but con- 
 structed upon similar principles. It is mounted in brickwork, 
 
 Fig. 187. 
 
 but can as readily and with as good results, have its position 
 in the more economical iron cylinder. Fig. 12. 
 
 By way of illustrating the necessary manipulations, we will 
 describe the different steps of the operation as commonly per- 
 formed. 
 
 The substance to be distilled is placed in the body A, the 
 pewter or tinned copper head c, is luted on and adjusted to 
 the pewter worm E, and the fire is lighted in the furnace. To 
 insure facility of management, the several parts of the ar- 
 rangement should be made so as to fit accurately to each 
 other. As the heat increases, the contents of the body or 
 cucurbit begin to boil, and that portion volatilizable at the 
 temperature of the applied heat mounts in vapor to the head 
 16 
 
234 DISTILLATION : — THE COOLER. 
 
 or capital c, there partially condenses, runs into the beak or 
 neck D, and ultimately into the spiral worm e, where, together 
 with any uncondensed vapor, it is liquefied and cooled by the 
 surrounding water previous to its exit into the recipient P, 
 which may be an open pan if the product is not volatile, and 
 a glass bottle or carboy if it is. The cooler I J K L, in which 
 the worm is immersed, consists of a wooden cistern filled with 
 water which requires to be constantly kept cool ; for this pur- 
 pose, therefore, there is a conduit N M attached, which re- 
 ceives cold water from the hydrant pipe R, and conveys it in 
 a constant stream to the bottom of the cistern, so that it may 
 displace the heated water, which has become lighter by expan- 
 sion, through the lateral outlet at the top. This water, already 
 heated, can be more economically used for making distilled 
 water than when cold, as it takes less fire to boil it when 
 transferred to the still. If the cistern is kept clean, it makes 
 an excellent reservoir for the supply of hot water to the labo- 
 ratory, as the still is frequently in use for making distilled 
 water, and for other purposes. 
 
 When fresh additions of liquid are to be made they can be 
 poured through the tubulure A. This saves the trouble of 
 taking oflf the head of the apparatus, which need only be re- 
 moved after the completion of the operation for the purpose 
 of cleaning the still and its parts. As the residuum is in 
 many instances as much the object of the process as the dis- 
 tillate, it must, when such is the case, be carefully removed 
 from the still, and transferred to a suitable vessel for pre- 
 servation or further reaction. 
 
 The size of the still varies with the amount of material to 
 be operated upon. For the ordinary purposes of the labora- 
 tory it need not exceed fifteen gallons capacity. It must be 
 proportioned so as to have as much heating surface as possi- 
 ble, while, at the same time, its height is sufiicient for the 
 foaming and frothing of its contents without danger of their 
 boiling over into the neck. 
 
 We have advised a spiral worm because that is the usual 
 form of refrigerants, an important point in the construction 
 of which is to provide as much cooling surface, and conse- 
 quently as great a length of pipe as possible in a small 
 space. Schrader's condenser, Fig. 188, which is preferred 
 by some manufacturers, because more easily cleaned, consists 
 
DISTILLATION IN RETORTS. 
 
 235 
 
 of a metallic ball, the upper part of which projects above the 
 water contained in the cooler. From 
 the lower side of this ball three Fig. 188. 
 
 straight tubes proceed, and conduct 
 the vaporized particles downwards 
 into the exit tube with which they 
 connect. The exit tube is closed at 
 its upper end with a cock, and open 
 at the other for the escape of the con- 
 densed liquid. 
 
 Whatever the form of the refrige- 
 rant, its mode of action is the same. 
 It is constructed so as to facilitate as 
 much as possible the perfect and rapid 
 condensation of the enclosed vapors. 
 The greater the amount of surface 
 which it presents to the water, the 
 more eflfectual its action ; for the 
 sooner the heat absorbed by the dis- 
 tillate in assuming the gaseous form, 
 is abstracted by the surrounding water, the more rapidly it 
 becomes condensed and cooled. The condensation may be 
 hastened by surrounding the recipients with a frigorific mix- 
 ture, which, if the vessel be of glass, must be at first applied 
 gradually, lest its too sudden cooling causes its fracture. 
 
 Distillation in Retorts, — Retorts are egg-shaped vessels, 
 answering a more convenient purpose than the still in the 
 nicer distillatory operations. They are mostly of glass, but 
 for some processes those of porcelain, earthen and stone-ware, 
 platinum and iron, are necessary. Retorts are also used in 
 technical operations, and the laboratory should be supplied 
 with a series ranging from those of an half ounce up to several 
 gallons capacity. Glass retorts should be made of hard, white 
 glass, free from lead. Those of German crown-glass are 
 very thin, but of uniform thickness and of sufficient strength, 
 and moreover withstand both high temperatures and the cor- 
 rosive action of acids and alkalies. The surface must be per- 
 fectly smooth and free from blur or striae. 
 
 Some judgment is required in the selection of retorts. One 
 properly constructed is exhibited in Fig. 189. It is seen that 
 the neck proceeds laterally from the summit of the body, 
 forming a wide tube at its origin which tapers gradually into 
 
236 
 
 DISTILLATION IN RETORTS. 
 
 a narrow beak. The arch of the retort should be so fashioned 
 as to reverberate any particles of boiling matter that may 
 spirt upwards against it, and thus prevent their overflow into 
 the beak. A large neck facilitates the process, because it 
 allows more room for the accumulation of vaporized matter, 
 and presents a proportionally less surface to the cooling in- 
 fluence of the atmosphere. 
 
 It is very essential that the curve between the neck and 
 the body a. Fig. 189, should be so formed as to make the 
 straight line a h form an obtuse angle, with the dotted line 
 h a. If, on the contrary, it is made as shown by Fig. 190, 
 which presents the usual form of those sold in the shops, the 
 
 Fig. 189. 
 
 Fig. 190. 
 
 Fig. 191, 
 
 vapors, condensing in the arch as far as the dotted line a 5, fall 
 back again into the body, whilst, in Fig. 189, the dividing 
 line, from which the distillate commences to flow, is much 
 nearer to the body. So that a retort, like Fig. 189, will dis- 
 til twice as rapidly as another similar to Fig. 190, which, how- 
 ever, when it has the form shown by the dotted lines c d a, 
 becomes equally convenient. 
 
 The pear-shaped retort. Fig. 189, being deeper in the body 
 or bulb, is better fitted for distilling volatile substances, and 
 others which foam and swell upon being heated. The globu- 
 lar form, Fig. 191, presents less depth, but more heating sur- 
 
DISTILLATION IN RETORTS. 
 
 23T 
 
 face, and is, therefore, better adapted to those liquids which 
 boil quietly and distil more slowly. 
 
 A great improvement to the plain retort, is the addition of 
 a glass stoppered tubulure to the neck, as at Fig. 191. The 
 tubulure should have its position exactly as shown in the cut, 
 so that the vapors condensing about it may flow back. Tubu- 
 lated retorts are preferable, because they are more readily 
 cleansed and charged than those of plain shape ; moreover, 
 they admit of fresh additions to their contents without the 
 necessity of disturbing the arrangement. 
 
 If the distillation is to be urged over an Argand lamp, the 
 neck of the receiver to be attached to the retort may be long, 
 and the connection may be made by inserting the beak of the 
 latter in its mouth, Figs. 192, 193, 194, and by rendering the 
 
 Fig. 192. 
 
 Fig. 193. 
 
 Fig. 194. 
 
 joint air-tight with a wrapper of India rubber cloth, as shown 
 at R in the figure. The funnel D is charged with water which 
 flows in a thin stream, regulated by the cock in the barrel, 
 upon the receiver covered with sponge or bibulous rags and 
 resting in a capsule c. 
 
238 
 
 DISTILLATION IN RETORTS. 
 
 If the retort is to be heated in a furnace, and the receiver 
 is globular, the junction of the beak and tubulure is tightened 
 by means of a perforated cork through which the beak passes, 
 and furthermore, if necessary, by a coating of flaxseed and 
 whiting lute. The arrangement is shown in Fig. 195. The 
 
 Fig. 195. 
 
 receiver B resting upon a straw ring in a wooden pail, is 
 cooled by a stream of water from the hydrant pipe I, which, 
 as it becomes warm, flows off into the funnel d leading into 
 the drain. 
 
 In order to increase the surface of the beak, and conse- 
 quently to facilitate the liquefaction of the vapors passing 
 through it into the receiver, there is often placed between the 
 beak of the retort and the tubulure of the receivers, but con- 
 nected with both, an adapter. Fig. 196, a pointed conical 
 tube of white glass, free from lead, which, when leading from 
 
 Fig. 196. 
 
 Fi-. 197. 
 
 (tC::: 
 
 a condenser to a bottle, takes a bent form as shown in Fig. 
 197. Fig. 198 exhibits a complete arrangement of a distil- 
 latory apparatus, combining a tubulated retort with an s tube, 
 an adapter, a recipient placed in a vessel with a constant 
 stream of cold water flowing into it, and a syphon tube with 
 a second receiver. The curved adapter is needed where the 
 receiver rests vertically instead of horizontally. 
 
DISTILLATION : — RECEIVERS. 
 
 Fig. 198. 
 
 239 
 
 As it is requisite, frequently, in distilling volatile liquids, 
 to have a larger extent of cooling surface than is presented 
 by the globular receiver, another form has been devised by 
 Liebig which is very convenient. It consists of a glass tube 
 25 to 30 inches long and one inch wide, connected with the 
 
 Fig. 199. 
 
 beak of the retort and running through a sheet brass cylinder 
 
 of 20 inches in lenorth and two or more inches diameter. The 
 
 I 
 
240 
 
 DISTILLATION IN TUBES. 
 
 metal tube is closed at each end with perforated corks, through 
 which the glass rod passes, and is held in a central position. 
 A constant stream of cold water supplied through the funnel 
 tube, passes into the cylinder, surrounds the glass tube, con- 
 Fig. 200. 
 
 Fig. 201. 
 
 denses the vapor therein contained, and becoming warm, passes 
 out through the exit pipe to give place to cooler water. The 
 figure above exhibits one mounted upon an iron stand with 
 joint and sliding rod; from which, for small operations, it may 
 be detached and supported by a wooden clamp. 
 
 For micro-chemical distillations, the necessary apparatus 
 may be formed of glass tubes blown into proper shape over the 
 blow-pipe table. Fig. 200 exhibits Clarke's tube retort and 
 receiver: — a the retort of an ounce capacity, h the receiver 8 
 by three quarter inches, and c the dis- 
 tilled liquor. The junction of the retort 
 and receiver (d) should be hermetical. 
 Plain bulbs a and tubulated b, Fig. 
 201, are other forms: — the tube b 
 of the latter serves for the suction 
 of the liquid to be heated, and may 
 afterwards be sealed in the flame of a 
 spirit lamp. 
 
 The means of heating these small 
 vessels, are the small spirit lamps Figs. 
 118, 116, except when it is required to modify the heat by a 
 sand-bath, which requires a larger lamp. The clamp supports 
 p. 176, heretofore described, are of very great convenience in 
 the adjustment of these tube arrangements. 
 
 A simpler form of tube retort is shown in Fig. 202. It is 
 readily made by closing a tube at one end and bending it in 
 
DISTILLATION : — PLATINUM RETOKTS. 241 
 
 a zigzag direction as represented in the drawing. The liquid 
 to be distilled is at a and the recipient at b. To render it 
 
 Fig. 202. 
 
 applicable to the generation and collection of gases, the tube 
 may be drawn out at its open end and bent downwards if 
 necessary to reach the receiver. 
 
 Platinum Retorts. — The size of these vessels varies from 
 a quart down to an ounce, these capacities being adapted to 
 all the purposes of an analytic and pharmaceutic laboratory. 
 The usual form is shown in Fig. 203. The body a is nothing 
 more than a stout crucible with a thick rim 
 d. The head 5, with the helm e, should be Fig. 203. 
 
 hammered from one piece or else very closely ^^^^ 
 welded together, and it should be ground at ^a^^^^^^ 
 its rim so as to fit perfectly to the mouth of ^Sj^S^^^^ 
 the still. W' I 
 
 Platinum stills are very useful for destruc- Jm^ § 
 tive distillation, for determining the amount ^^^ 
 of matter, if any, lost by substances at a 
 red heat, for the distillation of matters not readily volatilized, 
 of those which corrode glass, &c., and consequently, as a 
 substitute for lead in the preparation of fluohydric acid. 
 
 Those of a large size should be fitted with handles so as to 
 diminish their liability to defacement by transfer from place 
 to place. When heated over charcoal, they should be well 
 payed over with an external coating of fire clay paste. Other- 
 wise, the directions for using the platinum still, are the same 
 as those given for the crucible at p. 197. The gas or spirit lamp 
 will furnish the amount of heat required for most operations. 
 
 Iron Retorts. — All iron retorts 
 should be of cast metal. A very ^ Fig. 204. 
 
 neat form for small operations is 
 shown by Fig. 204. A simpler and 
 more economical apparatus is a mer- 
 cury flask. Fig. 205, with an iron gas 
 tube or gun barrel screwed into the 
 top, and reaching nearly to the bot- 
 tom, and another tube bent dowa- 
 
 Fig. 204. 
 
 4- 
 
242 DISTILLATION : — IRON AND PORCELAIN RETORTS. 
 
 wards. This arrangement, well fitted for distilling dry 
 
 Fig. 205. 
 
 substances which require a high heat, may be modified by 
 
 removing the centre pipe and 
 Fig. 206. inserting a screw plug, and 
 
 thus be made well adapted to 
 the distillation of mercury. 
 For distilling naphtha, caout- 
 chicine, and similar substances, 
 the usual form of a glass retort 
 is sometimes preferred. Fig. 
 206 exhibits one fitted with an iron tube or conduit, for con- 
 nection with a condenser or receiver, which for mercury, may 
 be an iron mortar or very thick glass bottle half filled with water. 
 Plate iron retorts, sometimes used for the generation of 
 gases by high heat, are referred to in the distillation of vola- 
 tile substances. 
 
 All of these iron* retorts are heated in furnaces, that repre- 
 sented by Fig. 206 being placed horizontally. 
 , When not in use, they should be greased to prevent oxida- 
 tion, and should be kept stoppered. 
 
 Porcelain Retorts. — These implements, of shape similar to 
 those of glass, are only used for dry distillations ; but re- 
 quire, that fracture may be avoided, to be very carefully 
 heated. Being opaque, they have not the advantage of glass, 
 which allows the inspection of the contents of the vessel. 
 
 * One per cent, of platinum, it is said, renders iron resistant to acid and cor- 
 rosive liquids. 
 
GENERAL RULES FOR DISTILLATION. 243 
 
 Earthenware and Stone Retorts. — The application of this 
 ware to the purposes of distillation is very limited. To render 
 it impermeable by gases, the retorts should be wet with a 
 solution of borax, or else payed over with a coating of paste 
 made from 9 parts of clay and 1 part of powdered borax, and 
 then heated to fusion and gradually cooled. 
 
 Gfeneral Mules for Distillation. — In the distillation of sub- 
 stances which require a high heat, the vessel may be placed 
 over the naked fire. If it is a metallic still, the cylinder, Fig. 
 12, affords every convenience for heating by this method. 
 Luhme's reverberatory furnace, Fig. 89, is the proper heating 
 implement for earthen and metallic retorts ; and the spirit or 
 gas lamp for those of glass and porcelain. When the nature 
 of the process requires a modification of the heat, it can be 
 accomplished by means of intermediate baths, which will 
 furnish any temperature required up to the boiling point — of 
 mercury. 
 
 Glass and porcelain retorts should, if possible, never be 
 heated over the naked fire, because of their great liability to 
 fracture. The impossibility of maintaining a uniform heat is 
 a serious objection to this mode, for the ebullition, though 
 rapid, is also unequal. When the above vessels are thus heated, 
 the same directions are applicable to their management as to 
 that of earthen or metallic retorts, though in the use of the 
 latter less care is requisite. The proper position of the retort 
 is in the centre of the furnace. Fig. 183, upon a crow-foot or 
 support. Fig. 107, resting on the grate. The retort having 
 been previously charged, its beak is then adapted to the re- 
 ceiver, and the joints closed by lute. A very small fire is 
 then ignited and increased, after the retort has become warm, 
 till it reaches to within a line or two of the level of the con- 
 tained liquid. If the coals project beyond this point, the sur- 
 face of the dry or upper part of the retort acquires a tempera- 
 ture so much higher than that of the substance which is being 
 heated, that the difference may cause its fracture when parti- 
 cles are projected against it. A certain degree of heat in the 
 upper part of the vessel is, however, necessary, so that the 
 opposite condition — the condensation of vapor in it, may not 
 occur ; and where the retort is heated unequally, it is some- 
 times necessary to place over it the dome of the furnace. For 
 the same reason, also, when a retort is heated over a spirit or 
 gas lamp, or by any other way in which the upper portion is 
 
244 GENERAL RULES FOR DISTILLATION. 
 
 exposed, that part should be covered with a dome. Fig. 207 
 exhibits such a one of earthenware for large retorts. A cone 
 
 Fig. 207. Fig. 208. 
 
 of pasteboard, Fig. 208, will answer better for smaller vessels. 
 The notch in the front allows its adaptation to the neck; but 
 while adjusted so as to effectually protect the upper part of 
 the retort from contact with air, it must be supported so that 
 its weight, when great, shall not endanger the safety of the 
 retort. 
 
 The addition of the fuel should be gradual, so that the fire 
 may be only sufficient to gently boil the contained liquid. The 
 coals should be first ignited to expel moisture ; and when the 
 operation is nearly completed, the fire must be skilfully ma- 
 naged. For greater safety, the ^^lass retorts should always 
 be coated exteriorly with a paste of refractory clay. 
 
 When the Argand or gas lamp is used as the means of heat- 
 ing, the retort need only be arranged upon a support, and 
 brought over the flame, which is to be applied gradually at 
 first, and slowly elevated until the glass has become heated 
 throughout. 
 
 Fig. 195 exhibits a retort properly located in a sand-bath, 
 this being the mode of heating retorts for the distillation of vo- 
 latile liquids, such as ethers and the like. The advantage of 
 the sand-bath over the naked fire for heating glass retorts, 
 particularly those of large size, is that it imparts a more uni- 
 form degree of heat, and prevents the possibility of fracture 
 from sudden changes of temperature. The sand should be 
 fine, and the layer upon which the bottom of the retort rests 
 about an inch or two deep according to the size of the retort. 
 The sand surrounding the retort should only reach to the level 
 of the contained liquid, and should be removed gradually as 
 it evaporates. 
 
DISTILLATION OF LIQUIDS. 245 
 
 To prevent condensation in the top, the upper portion of 
 the retort may sometimes be advantageously covered with a 
 woolen cloth. 
 
 When the operation is performed with a view to separate 
 two liquids which boil at different temperatures, the retort 
 must be either set in a bath which does not exceed the tem- 
 perature at which the more volatile liquid escapes ; or else, 
 when otherwise heated, the temperature must be regulated by 
 a glass thermometer. Fig. 84, entering the retort through its 
 tubulure, and adjusted by a perforated cork. 
 
 When the boiling points of different liquids are nearly equal, 
 the density of one of them may sometimes be increased by the 
 addition of some soluble matter, which, if both liquids are to 
 be saved, can afterwards be readily removed. 
 
 Too sudden ebullition must, in all cases, be avoided, and 
 the fire should be gradually increased, whether the heating 
 vessel be of glass or metal. The only exceptions to this rule 
 occur in the use of water or saline baths. 
 
 Distillation of Liquids. — The still is the most convenient 
 implement for the distillation of large quantities of material. 
 Retorts are more applicable to nicer operations. 
 
 The arrangement of a retort for the process of distillation 
 is very analogous to that of a still. The body is the recipient 
 of the matter to be heated, and is the portion to which heat 
 is applied ; the beak is the condenser, and the glass receiver, 
 the recipient of the distillate. The exit nozzle fitting upon the 
 end of the worm and leading into the recipient, should never 
 project so far as to dip into the distillate. If a globular 
 receiver is not at hand, an ordinary glass bottle for retort 
 distillations, or a carboy for those in the still, are excellent 
 substitutes, as it is very easy to make the connection by 
 using a curved adapter. Fig. 197, and adjusting it to the mouth 
 of the receiver, as in all other cases, through a perforated 
 cork. 
 
 Sometimes the receivers themselves are drawn out at the 
 neck into a tube which enters a flask, as at Fig. 209, or else 
 the tubulure is fitted with a perforated cork for the passage 
 of a tube which answers as well the purpose of a conduit. 
 The flask which receives this tube is also fitted with a perfo- 
 rated cork through which passes another tube, e. Fig. 210, 
 for the escape of uncondensed vapors. 
 
246 DISTILLATION OF LIQUIDS. 
 
 The refrigeration of the receiver is readily accomplished 
 by either of the arrangements shown at Figs. 194, 195. 
 
 Fig. 209. Fig. 210. 
 
 The uncondensed gases are allowed exit through a small glass 
 tube adapted to the tubulure in the top of the receiver, and 
 leading upwards under a hood, or else downwards into a bottle 
 of some fluid which absorbs them, and thus prevents the con- 
 tamination of the atmosphere. 
 
 It is of great importance that the vessels in use for distilla- 
 tion should always be free from foreign substances; and both 
 the retort, still, adapter, and worm, immediately after each 
 process, should be cleansed by repeated rinsings with water, 
 so that they may be clean and ready for the next operation. 
 
 As the ebullition of certain liquids is attended with foaming 
 and spirting, it is necessary to break the force of these sud- 
 den eruptions of vapor, by some mechanical means. This 
 can be effected often by the addition of platinum scraps to 
 corrosive liquids, and of fragments of glass to those which boil 
 at low temperatures and are without action upon it. This 
 precaution prevents damage to the vessel and allows the boil- 
 ing to proceed tranquilly. The use of the water bath obviates 
 the necessity of this preventive and is almost indispensable in 
 the distillation of liquids holding in solution certain vegetable 
 principles. 
 
 In distilling oil of vitriol in a glass retort, the deposition 
 of sulphate of lead endangers the safety of the retort and the 
 purity of the distillate hj an explosive ebullition. To avoid 
 
DISTILLATION OF LIQUIDS. 
 
 247 
 
 Fig. 212. 
 
 this difficulty, Berzelius sets the re- 
 tort one-third into the truncated cone ^^^' ^^^' 
 of sheet iron, Fig. 211, strews sand 
 around the edge of the cone, surrounds 
 it with brick, and hangs a flat cone of 
 sheet iron about a half inch above the 
 retort. The retort is half filled with 
 acid, and coals placed on the cone in- 
 side the bricks. Another method he 
 
 pursues is to precipitate the lead salt by dilution with water, 
 to concentrate the acid in a platinum capsule, and, finally, 
 to distil in a dome-topped furnace, a quiet distillation being 
 promoted by the introduction of platinum wire into the re- 
 tort. 
 
 If the retort is tubulated, there is no difficulty in charging 
 it neatly, because its contents can be added 
 without danger of spilling through a wide 
 barreled funnel; but when plain, it is neces- 
 sary, in order to prevent the adherence of 
 particles to the sides of the beak, to stand it 
 on end, as shown in Fig. 212, and to fill it 
 through the neck by means of a straight 
 funnel tube with its barrel reaching to the 
 bottom. 
 
 The matters, if solid, should always be 
 bruised or triturated to powder and added 
 portionwise. In this way the neck of the 
 retort is kept clean. 
 
 The joints of retorts and glass distillatory 
 vessels may be luted with strips of muslin 
 soaked in a solution of bone glue. Those of metallic vessels, 
 with a dough of whiting and flaxseed meal, which, when dry, 
 may be rendered still more impermeable, by a covering of 
 muslin, prepared as above, with bone glue. When one vessel 
 is adapted to the other by means of perforated corks, these 
 latter should be payed over with wax or more economically 
 with the flaxseed and whiting dough. If the distillate de- 
 composes organic matter, the use of corks, flaxseed and simi- 
 lar means, must be avoided, and the joints made tight by using 
 apparatus, the connecting parts of which are nicely adapted 
 to each other. 
 
248 
 
 DISTILLATION OF LIQUIDS. 
 
 Fig. 213. 
 
 All matters which readily generate very volatile products 
 should be distilled over baths, of which those made of liquids 
 are to be preferred. It is very easy to arrange the retort in 
 a suitable vessel, by resting it upon a braided straw ring. Fig. 
 213, and steadying its neck in a clamp support. The beak 
 of the retort should also be elongated by at- 
 taching it to a Liebig condenser. Fig. 199, so 
 as to extend the cooling surface. If the dis- 
 tillate is readily condensable, the receiver may 
 be kept sufficiently cold by a bath of cold water, 
 as shown in Figs. 194, 198 ; otherwise the use 
 of FRIGORIFIC MIXTURES becomes necessary. The mixture 
 should entirely surround the recipient, and as it becomes warm 
 or liquefies, new portions must be added. If ice or other solid 
 is used, the syphon in position, as shown at 6, Fig. 214, will 
 keep the pail constantly free from the liquefied excess. 
 
 Fig. 214. 
 
 The proper arrangement of an apparatus with Liebig's con- 
 denser, is shown in Fig. 215. 
 
 In the distillation, particularly of essences and oils, the 
 material, if it is ligneous, must be soaked, previous to its 
 transfer to the still, in which it should be made to rest upon 
 a cullendered diaphragm, Fig. 15, to prevent contact with 
 the heated bottom of the vessel. A proper vehicle is then 
 added and the operation proceeded with. The water, or 
 other liquid, and volatile matter are vaporized, and the 
 two becoming involved pass over together. When these 
 two products diff^er in density, as is commonly the case, a 
 
DISTILLATION OF VOLATILE LIQUIDS. 
 Fig. 215. 
 
 249 
 
 very convenient means of separating them as they pass 
 over, is afforded by the Florentine 
 receiver, shown in Fig. 216. A is 
 the body of the recipient, and D its 
 mouth through which the distillate 
 enters. The tubulure B is for the 
 reception of the beak (a curved 
 glass tube), c. As soon as the 
 condensed distillate reaches the re- 
 ceiver, the lighter body rises to the 
 top, and there retains its position, 
 and when the contained amount of the two fluids reaches the 
 level of the mouth of the beak, the one which is most dense 
 runs off. The level being kept thus constant, the lower stra- 
 tum of fluid is separated from the upper as fast as any distil- 
 late comes over, leaving the lighter liquid to be emptied from 
 the receiver after the completion of the process. 
 
 If the heavier product is the object of the distillation, as is 
 sometimes the case, then the form of the recipient may be 
 with advantage varied, as shown in Fig. 217. The stop-cock 
 in the barrel, allows its separation and discharge from the 
 lighter body as soon as a sufiicient quantity has subsided. 
 
 When volatile oils and some other bodies are obtained by 
 the above process, the water which is generally employed as 
 the vehicle, and which is separated as we have described, 
 should be reserved, as being already more or less charged 
 
250 
 
 COHOBATION. — RECTIFICATION. 
 
 Fig. 217. 
 
 2ZZ^Z2ZZZZZA 
 
 with volatile matter, it is economically used in redistilling the 
 same material, in case it should yield its 
 product reluctantly. This repeated dis- 
 tillation of the distillate over the same 
 material is termed Oohohation and is re- 
 sorted to necessarily, in many instances, 
 that the material may be entirely ex- 
 hausted of its volatile matter. 
 
 Reetification is the redistillation of the 
 distillate, either alone or with some absor- 
 bent material to free it from water, acid 
 or other impurity. 
 
 Distillation of Gases. — The term 
 "distillation" cannot in all instances be ap- 
 plied with entire precision to the processes 
 concerned in the manufacture of gases. 
 But as gaseous bodies when intended to 
 be retained are usually prepared by modes 
 precisely similar to those employed in 
 liquid distillation, it has been thought pro- 
 per to introduce their consideration in this place. 
 
 The generation and distillation of gases are generally made 
 simultaneous operations. As their elasticity is such as to 
 prevent condensation by ordinary means, they are either col- 
 lected in solution with water, or other fluid, or in their gaseous 
 state in gasometers. The arrangement of the required ap- 
 paratus, though bearing analogy to that for ordinary distilla- 
 tions, differs in many little but material points. 
 
 If the gas is readily evolved without the aid of heat, as in 
 the case of hydrogen, carbonic acid, sulphuretted hydrogen, 
 &c., the generator may be a simple flask A, Fig. 218. This 
 flask is the recipient of the material from which the gas is to 
 be eliminated. The funnel tube, reaching nearly to its bot- 
 tom, is the inlet of the acid, or other reagent, by which the 
 action is to be produced, and the bent tube is for the exit of 
 the disengaged gas. An ordinary wide-mouth green glass 
 bottle will answer the purpose excellently in most cases, as 
 exhibited in Fig. 219, which also shows an attachment by a 
 flexible India rubber joint of an angular tube, for passing the 
 gas through liquids when the influence of its absorption is re- 
 quired-^as in the precipitation of solutions in analysis. When 
 the generator is to be connected with a combustion or desic- 
 
DISTILLATION OF GASES. 
 
 251 
 
 CATION tube, as at Fig. 148, the bent tube can be removed. 
 In this instance, and, indeed, with better results in all cases. 
 
 Fig. 218. 
 
 Fig. 219. 
 
 Fig. 220. 
 
 T? 
 
 the angular tube should be blown with a bulb in its centre for 
 the reception of a plug of raw cotton, which intercepts the 
 passage of liquid. 
 
 The perforations in the cork must be only large enough 
 for the transit of the tubes, and the joints must be perfectly 
 tight. To render the cork itself impermeable, sealing-wax 
 should cover both of its surfaces. This arrangement of the 
 tubes obviates all liability of explosion. If condensation takes 
 place in the interior of the generating vessel, the resistance 
 from the funnel tube being more feeble than that opposed by 
 the water of the trough or receiving vessel, the air enters. 
 So also, if from any cause the passage of the gas through the 
 exit tube should be obstructed, its pressure upon the liquid in 
 the generator forces it upwards through the funnel tube, so 
 that it may escape instead of being allowed to accumulate 
 until explosion takes place. 
 
 When it is desirable to have the gas free from impurity, an 
 indispensable consideration when it is to be used in analyses, 
 it should, previous to its entrance, be passed through a small 
 quantity of water, or other fluid, which will dissolve out or 
 chemically attract such foreign matter as might have an in- 
 jurious effect upon the liquid to be acted upon. A suitable 
 
 I 
 
252 
 
 DISTILLATION OF GASES. 
 
 Fig. 221. 
 
 arrangement for such purposes, and one well adapted to the 
 generation of sulphuretted hydrogen gas, is shown in Fig. 
 221 ; A is the bottle containing the protosulphuret of iron, 
 water, and sulphuric acid, and provided 
 with funnel and disengagement tubes as 
 usual, the latter plunging in the water 
 of a smaller bottle B, from which a 
 disengagement tube D nearly as high as 
 that of bottle A issues, so as to lead the 
 gas disengaged, into a beaker or other 
 vessel containing the liquor to be ope- 
 rated upon : But the first disengage- 
 ment tube c is in two pieces united by 
 Indian rubber, and the bottles A B are 
 connected together by a strong band of 
 sulphurized Indian rubber, or of gutta- 
 percha G, so that the two bottles may be lifted at once as if 
 they were in one, wedges of cork E E being forced between 
 the two bottles so as to keep the strip of Indian rubber G and 
 the tube c properly adjusted. 
 
 When heat is required to cause or to promote the elimina- 
 tion of a gas, the generating vessels may be either tubes, 
 flasks, or retorts. 
 
 The facility with which glass tubes may be fashioned over 
 the blow-pipe flame, into any desired shape, renders them par- 
 ticularly applicable to small operations. Fig. 222 exhibits a 
 tube-apparatus for the distillation of hydrobromic acid. It 
 
 Fig. 222. 
 
 consists of a glass tube A B, to which is adapted a disengage- 
 ment tube conveying the gas under the bell c, filled with mer- 
 cury. The bromine is placed at A, and at B are small particles 
 
TUBE APPARATUS. 253 
 
 of moist phosphorus intermixed with bruised glass. Gentle 
 heat being applied at A, the vaporized bromine reacts upon 
 the phosphorus and water, producing phosphorous acid, and 
 disengaging hydrobromic acid gas, which passes over into the 
 bell-receiver and displaces the mercury. 
 
 A test tube, Fig. 116, fitted with a bent tube, serves very 
 conveniently for generating small quantities of gas for ana- 
 lytic or even experimental purposes. Any other forms that 
 may be needed will be suggested by the requirements of the 
 process or the ingenuity of the operator, and can readily be 
 fashioned after the instructions given upon Glassblowing. 
 
 Another very convenient form of tube generator is that 
 known as Marsh's Arsenic Apparatus, Fig. 223. 
 It consists of an elbowed tube of Bohemian glass, Fig. 223. 
 fitted with a stop-cock and jet, the whole to be sup- 
 ported by a suitable stand or pedestal. The length 
 of the tube may be sixteen inches, and its width 
 three-fourths of an inch. 
 
 The elbow being charged with some pieces of 
 purified zinc, the liquid containing the suspected 
 compound is acidulated with oil of vitriol and 
 poured into the long leg. The arsenical combina- 
 tion becomes decomposed by the nascent hydrogen 
 generated by the action of the sulphuric acid upon the zinc 
 and water, and makes its exit through the cock at the short 
 arm, as arseniuretted hydrogen, which may be recognized 
 when ignited by its bluish white flame, and the appearance of 
 the deposit upon a porcelain plate held over it. The stop- 
 cock allows the facility of regulating or stopping off" the sup- 
 ply of gas when required. 
 
 Next to the tubes, a Florence flask is the most economical 
 vessel for conducting small operations. Fig. 224 exhibits one 
 undergoing the process of being heated by a small spirit lamp. 
 The tripod upon which the flask rests, is surrounded by a tin 
 plate screen of a foot in height, to confine the heat of the lamp. 
 The exit tube conveys the gas into the beaker glass c, which 
 contains the solution to be saturated. Flasks of very thin 
 glass, and made uniform throughout, are blown expressly for 
 this purpose, as shown in Fig. 225. The exit tube is bent so 
 that it may be used with bell glasses over a pneumatic trough, 
 as in Figs. 222, 243. 
 
 Retorts are only convenient when large quantities of ma- 
 
254 
 
 COLLECTION OF GASES. 
 
 terial are to be operated upon, an(^ for most operations they 
 should be made of hard glass free from lead. For those pro- 
 
 Fig. 224. 
 
 Fig. 225. 
 
 Fig. 226. 
 
 cesses which require high furnace temperatures a metallic 
 retort is needed. Fig. 226 exhibits one of iron. It is fitted 
 
 with a very convenient coupling 
 or gallons screw by which the 
 neck may be connected with 
 flexible lead or other exit pipes. 
 The accompanying circular plate, 
 in two pieces, serves both as a 
 cover to the furnace and as a 
 support for the neck of the re- 
 tort to retain it in place. The 
 cheaper mercury bottle supplies 
 the place of this apparatus ad- 
 mirably in nearly all instances, 
 and with the gun barrel attach- 
 ment, as shown in Fig. 226, or 
 other tube, is particularly useful 
 in the manufacture of oxygen. 
 
 Collection of Gases. — Gases are either collected in the 
 aeriform state or else in solution. When generated extempo- 
 raneously, merely as precipitants of some solution, they are 
 passed through the liquid contained in a beaker glass, as 
 at Fig. 224, and Fig. 221, a tightly stretched paper cover 
 being in general all that is required to confine the unab- 
 sorbed excess in the vessel. 
 
 If a liquid, as well as a gaseous product, is generated 
 
COLLECTION OF GASES. 
 
 255 
 
 simultaneously, then the arrangement of the apparatus may- 
 be, as shown in Fig. 227. The use of this may be well illus- 
 trated by a reference to the manufacture of nitrous oxide gas. 
 The nitrate of ammonia, the material from which it is gene- 
 rated, is placed in the retort, the beak of which is adjusted, 
 by means of a perforated cork, to the tubulure of a globular 
 receiver. This receiver in its turn is connected by bent glass 
 tubes, rendered flexible by a caoutchouc joint, with a Wolffe's 
 bottle. The latter, deriving its name from that of the in- 
 ventor, consists of a bottle, the size of which may vary with 
 the extent of the operation, having in this instance three 
 tubulures, each of which is fitted with a perforated cork for the 
 
 Fig. 227. 
 
 passage of glass tubes. The first tube a 5, Fig. 229, con- 
 ducts the gas from the receiver. The central tube c c?, acts 
 as a safety valve : the gas cannot escape through it, but if 
 condensation ensues within the bottle, the external air rushes 
 in and prevents the liquid from running over into the reci- 
 pient or next bottle, if there are two connected, by reason of 
 absorption. The third tube a, is the exit tube for conveying 
 the gas directly into the recipient. 
 
 The retort, receiver, and Wolffe's bottle having been con- 
 nected together, and the joints hermetically closed, heat is 
 then gradually applied by means of the spirit Argand lamp. 
 The eliminated gas passes over into the receiver, there depo- 
 sits the aqueous vapor with which it is involved, and continues 
 on to the Wolffe's bottle containing water, in its transit through 
 
256 COLLECTION OF GASES. 
 
 "which it parts with the rest of its aqueous vapor, and its other 
 impurities, and ultimately reaches the exit tube a. If the gas 
 is to be received into caoutchouc bags. Figs. 129, 130, and 
 pages 216, 255, for inhalation or other purposes, the connection 
 may be made directly, as seen in the figure, by means of a 
 gallows screw, which allows an empty bag to replace another 
 which is charged whenever desired. If the bags are intended 
 as reservoirs for the preservation of the gas, their necks are 
 fitted with gallows screw stop-cocks and connecting nipples. 
 Those of small size, for the purpose of inhalation, are fitted 
 with an ivory mouth-piece m. Fig. 227. 
 
 If the gas is to be conducted into a Pepy's gasometer, as 
 at Fig. 234, or under a bell-glass over a pneumatic trough, 
 as at Fig. 243 ; then instead of the stop-cock there must be a 
 flexible bent tube of shape similar to that attached to the 
 flask. Fig. 219, adapted to the third tubulure of the bottles. 
 Lead pipe of small bore may be used as a conduit when the 
 generated gas is not corrosive. The gallows screw then be- 
 comes the proper mode of connection. 
 
 To favor the condensation of the aqueous impurity of the 
 gas, the globular receiver should be kept cool during the dis- 
 tillation. So also the Wolffe's bottle must be surrounded by 
 water, or a cooling mixture, when the gas is very volatile, 
 otherwise the elevation of temperature, which generally occurs, 
 may cause its dissipation. 
 
 When two or more gases are generated simultaneously, they 
 may be separated by the presence in the receiver of an appro- 
 priate liquid, which is a solvent of one, but not of the other 
 of them. Thus oxygen may be freed from carbonic acid by 
 passing the mixture through a solution of caustic potassa, 
 which absorbing the acid, becomes carbonated, and allows 
 the transit of the purified oxygen. This mode 
 Fig. 228. is adapted for this and other purposes in or- 
 
 ganic analysis, the requisite apparatus being 
 a five bulbed white glass receiver of the form 
 shown by Fig. 228. Its arrangement for the 
 purpose is given in Fig. 103, a being the com- 
 bustion-tube, in which the substance to be 
 analyzed is introduced after its mixture with 
 oxide of copper or chromate of lead, from 
 which it obtains the oxygen necessary for its 
 
GENERATION AND ABSORPTION OF GASES. 257 
 
 combustion. The figure represents the tube in its position 
 during the analysis, in the trough-shaped furnace of sheet- 
 iron, in which it is heated by being surrounded with ignited 
 charcoal. By means of a perforated cork, the combustion- 
 tube is connected with the tube in which the water pro- 
 duced by the combustion is condensed. It is filled with 
 chloride of calcium in order to absorb all the vapors from the 
 carbonic acid, which passes through it into the apparatus 
 m r Pj through which it would be forced, were it not absorbed 
 by the solution of caustic potassa contained in the lower bulbs. 
 After the completion of the combustion, the carbonic acid 
 which remains in the combustion-tube is extracted from it, by 
 breaking off" its pointed extremity and applying suction to the 
 other end of the potassa apparatus at ^, by which air is drawn 
 through the whole apparatus, and the carbonic acid absorbed 
 by its passage through the solution in the potassa bulbs. The 
 weight of the water and the carbonic acid, is obtained by 
 weighing the chloride of calcium tube and the potassa appa- 
 ratus before and after the combustion. For this purpose each 
 may be conveniently suspended to the supplementary pan, 
 Fig. 62, of the analytic balance, p. 105. 
 
 In the instance we have been referring to, the WolflPe's bot- 
 tle is used for the purpose of retaining watery vapor or other 
 impurities in its contained fluid. Its most common employ- 
 ment, however, is when the gas itself is intended to be pre- 
 served in solution in water or other fluid. For this purpose, 
 the number of Wolfi'e's bottles is often increased to three or 
 more, which are connected together by tubes with flexible 
 joints. In this manner, any gas that has remained unab- 
 sorbed by the liquid in the first bottle, is successively exposed 
 to the dissolving influence of that in the others, until it be- 
 comes entirely liquefied. The Wolfi'e's bottles may, in many 
 cases, be well replaced by wide-mouthed jars or bottles, with 
 two or three perforations in their corks, and which may be 
 made to answer all the purposes of the more expensive appa- 
 ratus. 
 
 Fig. 229 represents an apparatus for the generation and 
 absorption of gas ; a being the heating vessel, the contents 
 of which should fill only half its capacity, so that they 
 may not upon too sudden reaction, run over into the recipi- 
 ent : 5, the recipient either for the condensation of aqueous 
 
258 ABSORPTION OF GASES ; — WOLFFE'S BOTTLES. 
 
 vapor, or the abstraction of impurity by a contained vehi- 
 cle, and the three Wolffe's bottles, half filled with water, the 
 
 Fig. 229. 
 
 receptacles of the eliminated gas. As the volume of the 
 liquid in the "Wolffe's bottles increases proportionally to the 
 amount of gas received and dissolved, they should not be more 
 than half filled at the commencement. So also the interme- 
 diate receiver should have but a very shallow depth of liquid, 
 else it will take up gas as well as the impurities, and thus cause 
 a loss. The water in the first bottle is the first to become 
 saturated, and all the gas which is not absorbed passes over 
 into the second and third bottles. This arrangement is that 
 usually adapted for the distillation of acid, ammoniacal and 
 other gases, which are condensed by solution. When neces- 
 sary, any other liquid may be made to replace the water in 
 the bottles. For example, aqua ammoniae when it is desired 
 to make a chloride or carbonate of that base, and lime milk for 
 the solution of chlorine, &c. &c. 
 
 When the gas is to be generated by reaction of liquid upon 
 a solid, the latter must be put into the flask before the stop- 
 per and tube are adjusted. The liquid can then be added 
 through the S tube as often as it is required to continue the 
 disengagement. If the gas is heavier than the solvent liquid, 
 
ABSORPTION OP GASES ; — SAFETY TUBES. 
 
 259 
 
 the disengagement-tube need dip but slightly beneath its level ; 
 and vice versa.'*' 
 
 ^ Safety Tubes. — When in the course of distillation, a mo- 
 mentary suspension of the heat or generating impulse causes 
 a partial vacuum in the heating vessel, the liquid into which 
 the disengagement tube dips is forced by the presence of the 
 atmosphere into its bore, and ultimately into the vessel itself. 
 
 This entrance of liquid into the generating vessel may 
 result also from its sudden cooling, by the entrance of cold 
 water or by other means. 
 
 The results of this absorption are sometimes the fracture of 
 the vessel, and more frequently irreparable injury to its con- 
 
 Fig. 230. 
 
 Fig. 231. 
 
 Fig. 232. 
 
 tents. To obviate these inconveniences, we use a safety tube, 
 the usual forms of which are shown by Figs. 231, 232. The 
 first, which is called an s tube from its similarity to that letter, 
 
 * There are several points to be remembered in the generation and collection 
 of gases. 
 
 1. AH gases owe their existence as such to a certain elasticity, by reason of 
 which they press upon the sides of the vessels in which they are enclosed. 
 
 2. The tension or elastic force of a gas is proportional to its quantity: — it 
 augments with the temperature and decreases by refrigeration. 
 
 3. The atmosphere weighs upon all bodies, its pressure being usually equal 
 to the weight of a column of water 34 feet high, or of a column of mercury 
 30 inches. 
 
 4. That liquids (in equilibrium) press equally in all directions. 
 
 These facts, therefore, render necessary tlie use of the safety tubes c c c, Fig. 
 229, and Welters, or the s lube. Figs. 230, 231, 232. 
 
260 ABSORPTION OF GASES ; — SAFETY TUBES. 
 
 is most used, but either of them may be employed in the fol- 
 lowing manner. If the generating vessel has only one 
 aperture, its cork having been tightly fitted and rendered 
 impermeable by coatings of sealing wax or other cement, on 
 its upper and lower sides, is then to be perforated with two 
 holes, one for the transit of the s tube, and the other for that 
 of the exit tube. The tubes being tightly adjusted in the 
 holes as shown in Fig. 230, and the cork fitted to the mouth 
 of the generating flask, a quantity of water or sometimes of 
 other liquids, as mercury, is poured into the s tube. When, 
 during the process, the level is stationary in the bulb B, and 
 in the part A of the tube, the apparatus is hermetically closed. 
 If, however, a condensation of vapor takes place in the inte- 
 rior of the flask, the external pressure of the atmosphere 
 weighs alike upon the liquid F of the trough, and that in the 
 s tube ; but as the latter ofi'ers the least resistance, the air first 
 makes its contained fluid advance towards the flask, and then 
 enters in bubbles into it, thus preventing the absorption of 
 liquid from the trough or receiver. 
 
 If mercury is used, its relative density to water must be re- 
 membered, and the column of metal in the curve, should be 
 as low as possible. As a column of mercury requires one of 
 water nearly fourteen times its height for its support, it fol- 
 lows that if the former is too high, the gas passes back more 
 rapidly into the recipient during condensation, from the dis- 
 engagement tube than the air traverses the metallic mass in 
 the s tube. Mercury is used when the Wolff"e's series com- 
 prises a number of bottles; so that the opposing force of the 
 contained liquid may not be sufficient to cause the disengage- 
 ment of the gas through the S instead of the exit tube. 
 When operating with a mercurial trough, the S tube, Fig. 231, 
 without a bulb is used. The quantity of metal which it 
 should receive must however be such that the pressure of the 
 gas will meet with as strong a resistance from it as the liquid 
 in the trough. When flasks are replaced by retorts, the latter 
 should be tubulated, so that the safety tube may be adapted 
 to its tubulure by means of a perforated cork. 
 
 If the retorts are necessarily plain, as in certain distilla- 
 tions by furnace heats, then the safety tube can be attached 
 to the disengagement tube E Fig. 243, over the blow-pipe 
 flame. The liquid is introduced at H i. This kind of tube 
 
GASOMETERS. — PEPY'S GASOMETERS. 
 
 261 
 
 known as "Welters is very fragile, and requires careful manage- 
 ment and handling. 
 
 Grasometers. — When the eliminated gas is to be preserved 
 free from air, in large quantities for laboratory purposes or 
 transportation, it is received in gasometers. 
 
 Pepys G-asometer. — The most convenient gas holder is 
 that known as Pepy's, Fig. 233. It consists of a japanned 
 zinc hollow cylinder 16 by 12 inches, surmounted by a trough 
 B of 9 by 12 inches, making the total height of the apparatus, 
 
 Fig. 233. 
 
 r^^ 
 
 including that of the supports, three feet. Near the base of 
 the cylinder is a lateral gulley placed obliquely and cut with 
 a thread to receive a screw plug which closes it hermetically. 
 The tube D, supporting the centres of the vessels, and fitted 
 with a cock, allows a communication between the reservoir and 
 trough. A second tube s c i at the side, also fitted with a 
 cock, passes from the upper cylinder into the lower, and de- 
 scends, as shown by the dotted lines, to within a few lines of 
 the bottom. The stem e is merely a support, and serves no 
 other purposes. The coupling and stop-cock in the side near 
 the top serve for connection with a jet, or for fitting on a 
 bag or ^ bladder. The glass gauge k graduated into cubic 
 inches, is adjusted firmly and hermetically by means of sockets 
 
262 GASES RECEIVED IN GASOMETERS. 
 
 at the top and bottom of the cylinder. To prevent fracture 
 it is embedded in a frame-work of the same metal as the gas- 
 holder. 
 
 The manner of using the apparatus is as follows: — close 
 the mouth g, and fill the reservoir with water. For this pur- 
 pose the water is poured into the trough 5, and allowed to 
 run down through the opened tubes d and c. The cock / 
 being also opened, the confined air escapes as the water enters, 
 and in proportion as the reservoir a is filled, the water rises 
 in the tube k and hence the latter will indicate when it is full. 
 As soon as this occurs and water runs through the pipe/, the 
 cock of the latter must be closed, and the residual air allowed 
 to escape through the still open tube d. If, upon gently shak- 
 ing the vessel, no more bubbles appear, then all the cocks are 
 to be closed and the apparatus mounted over a tub, of diameter 
 some six inches or more, greater than that of the gasometer and 
 the gullet ^, is then opened. As the highest part of the edge of 
 the inner aperature of this gullet is lower than the lowest part 
 of the edge of the outer aperature, by a half inch or more, 
 the water cannot escape unless the air simultaneously finds 
 access, inwards, from above, by leak holes or otherwise. If, 
 after the gush of a small portion when the plug is first re- 
 moved, there should be any further leakage, it will be indi- 
 cated by the gauge tube. 
 
 All being tight, the beak of the retort, or end of the con- 
 duit tube of the generating vessel, is introduced into the 
 gullet, as shown at A, Fig. 234. The eliminated gas entering 
 the receiver, displaces the water which escapes at ^, and falls 
 into the pail beneath. As soon as the vessel is full, which will 
 be known by the examination of the gauge, or when a suffi- 
 cient quantity has been collected, the disengaging tube or 
 beak is withdrawn, and the gullet closed with the plug. 
 
 If it is desired to fill a gas bag from the reservoir, it must 
 be fitted with an appropriate cock and nipple for connecting 
 with the coupling cock/, and the pressure of the water with 
 which the trough h has been partially filled, should be made 
 to act upon the gas by opening the cock c. So also, when 
 the gas is to be transvased into bell-glasses, these latter are 
 filled with water to displace all air, inverted, and then brought 
 directly over the opened tube c?, as shown in Fig. 234. As 
 the water enters from the trough through the tube c, gas 
 
GASES TRANSFERRED FROM GASOMETERS. 263 
 
 escapes into the jar by the exit pipe d. When the vessel is 
 filled, communication must be shut off by closing the cocks. 
 
 When a greater pressure is required, than can be given 
 by the water contained in the trough, it can be obtained by 
 means of a long-barreled funnel o. Fig. 236. When this is 
 screwed by its threaded nipple p, into the socket «, Fig. 234, 
 and filled with water, there is a pressure of nearly six feet. 
 
 Fig. 235. 
 
 By abridging the length of the barrel to q, the pressure is 
 diminished to a little less than four feet. When two of these 
 gasometers, filled the one with oxygen and the other with 
 hydrogen, are united by means of a double jet. Fig. 235, 
 connected by its branches a h with the cocks / of the re- 
 servoir, they form what is called the hydro-oxygen or com- 
 pound BLOWPIPE. 
 
 Mercurial G-asometer. — When the eliminated gas is soluble 
 in water or altered by contact with that liquid, it may with 
 propriety be collected over mercury. For this purpose Pepy 
 has contrived the arrangement shown in Fig. 237, which ob- 
 viates the expense and inconvenience of filling the cistern 
 with mercury. It is made of iron, and consists of a bell 
 A A B B, which has a cock o at its summit, and which is im- 
 mersed in a cylindrical iron cistern M N o P. This cistern is 
 the reservoir for the mercury, but in order that as little as 
 possible may be used, an iron core D E occupies its centre and 
 allows an interval between it and the sides of the cistern only 
 sufficient for the jar and mercury to make it tight. A glass 
 tube a b cemented tightly to the top of this inner cylinder, 
 traverses it and serves as a conduit of the gas into the bell, 
 which is maintained in a vertical position by a movable elbow 
 adjusted to the frame of the apparatus. 
 
 A cock c is adjusted to the tube a 6, and puts it in commu- 
 nication with the eprouvette or small inverted bell F, placed 
 upon a dish containing mercury. 
 
 In using this gasometer, the cavity M N P is filled with 
 
264 
 
 MERCURIAL GASOMETER. 
 
 mercury, the cocks c and e are opened, and after the bell has 
 been pressed down to its full extent in the metal, the cock c 
 is closed. 
 
 Fig. 236. 
 
 Fig. 237. 
 
 \ 
 
 7 
 
 The disengagement tube is then introduced under the mouth 
 of the eprouvette and the generation of the gas proceeded with. 
 Each bubble as it enters the bell elevates it proportionately; 
 and when it has received a quantity equivalent to the volume 
 of the capacity of the tube and of the eprouvette, the cock c 
 is to be opened again and the bell depressed. The greater 
 part of the gas which has entered and the air with which it is 
 mixed, is thus forced to escape. A repetition of this manoeuvre 
 two or three times will insure the entire expulsion of the air ; 
 when the portions of gas given off can be collected and pre- 
 served for use. When the bell is full, the cock c is to be 
 closed and the retort J removed. 
 
 To transvase any portion of the gas that may be wanted 
 for use, it is only necessary to put the tubulure c in commu- 
 
DEVILLE S GASOMETER. 
 
 265 
 
 nication with the vessel in which it is to be received, by open- 
 ing the cock and then to depress the bell in the mercury. 
 
 A scale graduated upon the side of the bell will allow an 
 estimation of the volume expended. 
 
 Devilles Gasometer. — This apparatus, constructed upon 
 the same principle as Harriot's vase, is most used in organic 
 analysis. 
 
 Fig. 238 exhibits the arrangement. A A is a tubulated 
 bottle filled with water ; and 
 
 a a a is the tube 
 gaging the gas 
 generator. Each 
 gas displaces an 
 
 for disen- 
 from the 
 bubble of 
 equal vo- 
 
 Fig. 238. 
 
 c=r 
 
 lume of water, which is con- 
 ducted off by means of the 
 syphon h b h, and the process 
 should be continued until the 
 expulsion of all the water, 
 save just enough to fully close 
 the orifices of the tube. 
 
 When the gas is to be dis- 
 engaged for use, fill the fun- 
 nel E with water and open the 
 cock/. The pressure of the 
 water descending into the 
 flask forces the gas into the 
 tube i i. 
 
 A flexible tube h i can then 
 be adapted to the orifice of 
 the vessel into which the gas is to be introduced. 
 
 This gasometer is especially employed for holding oxygen 
 to be passed over oxide of copper in tubes, after organic ana- 
 lyses, and to remove all carbonic acid that it may contain, 
 it is passed through a flask containing an aqueous solution of 
 caustic potassa. 
 
 The small bottle c contains the concentrated sulphuric 
 acid and the tube u, potassa in one branch and chloride of 
 calcium in the other. 
 
 If the oxygen is kept in this holder for too long a time, it 
 becomes altered and contaminated with atmospheric air. 
 
 Pneumatic Troughs. — In most manipulations with gases, 
 
266 
 
 PNEUMATIC TROUGHS. 
 
 particularly when they are reqmred for immediate use or for 
 temporary purposes, they are collected over the pneumatic 
 trough. As the bell glasses* into which they are to be re- 
 ceived, must first be freed from contained air, it is necessary 
 to immerse them in an appropriate liquid. Water and mer- 
 cury are the two fluids almost universally employed, the first 
 being used for all those gases which are not soluble in it, and 
 for some which are only so in a slight degree, and the latter 
 for those which are absorbed by water, and which exert no 
 chemical action upon the mercury. Hence the distinctive 
 terms, water and mercurial trough. 
 
 Water Trough. — A wooden pail, square or oval, with a 
 
 * Bell Glasses — Gas Jars or Receivers. — The arrangement of an experimental 
 laboratory is incomplete without a series of bell glasses, varying in size from a 
 gill upwards to one gallon. They should be of glass, preferably of white glass 
 free from lead, should be made so as to combine strength and neatness, and 
 should have a knob at the summit for convenience of handling. The rim of the 
 mouth must be ground perfectly smooth and level, so that when resting upon 
 an unground glass disk or an even bottomed plate, the joint may be tight. Fig. 
 239 exhibits a plain jar for ordinary uses ; and Fig. 240 a similar implement 
 
 Fig. 239. 
 
 Fig. 240. 
 
 Fig. 241. 
 
 Fig. 242. 
 
 X 
 
 tubulated at its summit and closed with a glass stopper. This opening not only 
 allows the facility of forming connections with other apparatus, but also that of 
 filling it readily with liquid merely by depressing it while unstopped, vertically 
 in the water trough. The air escapes through the tubulure in proportion to the 
 rise of fluid in the receiver, which when full is to be stoppered and placed 
 upon the shelf to receive the gas. Sometimes the tubulures are fitted with stop- 
 
BELL GLASSES ; — GAS JARS. 
 
 26T 
 
 little management can be converted into a most convenient 
 water trough, Fig. 243. It should be of capacity sufficient 
 
 Fig. 243. 
 
 to allow the thorough immersion of bells of any size required 
 for experiment. One of a foot in depth, sixteen inches in 
 length, and ten inches in width, will be very suitable; — a ves- 
 sel G of this size fulfilling almost all the requirements of an 
 
 Fig. 244. 
 
 cocks, as seen in Fig. 241, which add to the convenience of the jars in many 
 operations, and particularly when it is desired to pass 
 a measured quantity of gas from the receiver into an- 
 other vessel attached as heretofore described at p. 109. 
 For this purpose the bell must also be graduated as 
 seen in Fig. 242, 
 
 If the vessel into which the gas is to be received is 
 a bladder instead of a glass bell, it must be fitted with 
 a coupling cock, freed from air as much as possible by 
 compression with the hands, then connected with the 
 air-pump, Fig. 32, and p. 109, or syringe, Fig. 244, and 
 completely exhausted by suction. The cock is then 
 closed, the bladder detached from the syringe, and 
 adapted by its coupling to the cock of the bell. Com- 
 munication being opened the gas passes into the bladder 
 upon the depression of the jar. 
 
 By grinding the surface of the ledge very accurately, 
 and fitting the mouth of the bell with a ground glass 
 disc, which by the intervention of a little grease may 
 form an airtight joint, gases may be retained unaltered for a limited period. 
 
268 GASES RECEIVED OVER WATER TROUGHS. 
 
 experimental laboratory. Near to the top, in the interior, 
 should be lateral flanges for the support of a sliding shelf a. 
 This sliding shelf should have sufficient surface for the sup- 
 port of several bells or jars F at a time, and may extend 
 over half of the trough. It is perforated with holes for the 
 reception of the beak of the disengaging vessel as seen at 5, 
 Eig. 243. 
 
 A very convenient water bath for the collection of gases, 
 may be formed of a deep earthenware dish, or other vessel in 
 common use, by the addition of the bee-hive shelf. Fig. 245. 
 This shelf, generally made of porcelain, is a sub- 
 Fig. 245. stitute for the shelf of a regular trough, and serves 
 for the support of the bell glasses or other re- 
 ceivers. It may be two inches in diameter and one 
 inch high, for a dish one foot wide and two inches 
 deep, and proportionally larger for one of greater 
 dimensions. The disengagement tube enters the semicircular 
 opening at the base and delivers the gas into the receiver by 
 its curved end protruding through the hole in the centre. 
 Part of a loaded wooden box, a metallic support, or other ex- 
 temporaneous arrangement may in many cases be so ad- 
 justed to take the place of the common, or the bee-hive shelf 
 — and to answer every useful purpose. 
 
 It is indispensable that the trough should be made tho- 
 roughly water tight and should be well hooped. For further 
 protection it might be covered over with several coats of 
 plumbago paint. Leakage being thus provided against the 
 vessel may be used upon either the operating or centre table. 
 The stop cock near the bottom allows the exit of the water 
 when it has become dirty, acidified, or otherwise unfit for 
 use. 
 
 The level of the contained water must always be half an 
 inch or more above the top of the shelf. When the bell is to 
 be charged, it is first completely immersed in the water so as 
 to expel all contained air, then taken up by the knob, raised 
 to a vertical position and carefully slid along with its mouth 
 in the water to the shelf and placed immediately over the hole 
 through which the disengagement-tube enters. As the gas 
 bubbles up into the bell the water is displaced, and when it is 
 filled, it can, if necessary, be drawn aside and replaced by an- 
 other. So the process is continued until all the gas generated 
 has been received. 
 
THE MERCURY TROUGH. 
 
 269 
 
 Fig. 246. 
 
 As the first bubbles of gas eliminated are contaminated with 
 air, they should be rejected; consequently the beak of the dis- 
 engagement tube ought not to be brought under the bell re- 
 ceiver until the gas commences to pass over freely. 
 
 The Mercury Trough. — The high price of mercury renders 
 necessary an economical construction 
 of the trough in which it is kept. Fig. 
 246 exhibits one of convenient form. 
 It consists of a well-japanned cast- 
 iron trough, twelve inches long, seven 
 inches wide, and two inches deep. 
 The bottom, towards the side, is sunk 
 throughout its length into a well two 
 inches wide and one and three-quarter 
 inches deep, and is expanded at its end 
 into a circular cavity. This cavity 
 allows of the immersion of the tubes 
 or bells in a moderate depth of mercury without the expense 
 of filling the whole trough being incurred ; and the circular 
 end being larger than the other portion of the canal, allows 
 the use of receivers of from two to three inches in diameter. 
 
 When this cavity is not in use and the mercury required to 
 fill it is needed in the other part of the trough, it is closed 
 with an exactly fitting iron plug which accompanies the vessel 
 for this purpose. 
 
 The trough is placed upon the operating table and is mani- 
 pulated with in the same manner as the water trough. For 
 the convenience of supporting tubes in a vertical position, 
 there is generally an accompanying clamp with sliding rod, 
 which is attached to the side. 
 
 The small mercurial trough of porcelain. Fig. 247, very 
 useful in organic analysis, contains usually from ten to twelve 
 pounds and serves also very conveniently for experiments 
 upon a small scale. 
 
 Fig. 248 exhibits a cylindrical glass trough which is used 
 ."with tubes in organic analysis. It is of glass, fifteen and a 
 lalf inches high, and is widened at the top. The drawing 
 •epresents the introduction of ley into a graduated tube by 
 leans of the pipette a over a column of mercury. The tip 
 »f the pipette is curved so as to facilitate its entrance under 
 bhe mouth of the tube. This plan is adopted sometimes in 
 ieu of that given at p. 256, for the separation of two gases. 
 
270 
 
 GASES COLLECTED OVER AIR. 
 
 by presenting to both a third substance for which either of 
 them has an affinity. 
 
 Fig. 247. 
 
 Fig. 248. 
 
 Fig. 249. 
 
 In the course of time the mercury of the trough becomes 
 debased, by use, either with water, metals, or suspended mat- 
 ters. The water being specifically lighter, may very readily 
 be removed by spreading sheets of bibulous paper on the sur- 
 face of the mercury and renewing them as fast as they become 
 imbued. The metals are separable by distillation, the mer- 
 cury passing over pure into the recipient. 
 
 If the impurities are merely coarse suspended particles as of 
 metallic oxides, straining, by compression with the hands 
 through a chamois leather bag, will retain them, and even 
 most amalgams, while the mercury passes through the pores 
 entirely or almost pure. 
 
 Gases collected over air. — Although chlorine can for tem- 
 porary purposes be collected over hot water in which it is not 
 dissolved, that body as well as iodhydric and bromhydric acids 
 and certain other gases which are soluble in water, or which 
 attack mercury, are sometimes collected in receivers or bot- 
 tles filled with air. 
 
 If the gas is lighter than air, the end of the disengagement 
 tube should reach to the upper part of the inverted vessel. 
 As the gas enters, the air is displaced and goes out below, 
 and the jar is known to be full when the gas escapes also. 
 The jar must then be slowly and carefully removed so that 
 the vacuum left by the withdrawal of the tube, may be com- 
 
TRANSFER OP GASES. 271 
 
 pletely supplied by the gas simultaneously entering, and its 
 mouth be closed with a plate of ground glass, cork, piece of 
 caoutchouc, or other suitable means. 
 
 When the gas is heavier than air, as is the case with chlo- 
 rine, the disengagement tube should enter to the bottom of 
 the receiver, the mouth of which should be closely covered 
 with a pasteboard disk. When the gas begins to escape at 
 the mouth, the jar is full, and, after being closed with a 
 ground glass plate or other stopper, carefully removed aside. 
 
 Transfer of Crases. — It is frequently necessary to transfer 
 portions of gas from a large vessel to a smaller one for the 
 purposes of experiment or measurement.* Having already 
 given the mode of transferring from a gasometer we will now 
 speak of transvasement over troughs. 
 
 If the jar or reservoir of gas is still upon the shelf of the 
 pneumatic trough, the smaller vessel which is to receive a por- 
 tion of its contents is to be entirely immersed in the fluid of 
 the trough, and whilst full, conveyed bottom downwards to the 
 shelf and there placed, so that it will project over the edge 
 about a third of its diameter. The reservoir is then brought 
 forward and the mouths of the two put in connection as shown 
 in Fig. 250 by inclining the reservoir so that their edges may 
 be in contact; — the gas then passes up in bubbles and by a 
 little dexterity the rapidity of its flow can be easily regulated. 
 
 At pages 109, 133 and 134, we have already given direc- 
 tions for the transfer of gases into tubes and globular vessels. 
 
 Bladders are filled from the cocked receivers, Fig. 241, as 
 directed at p. 267. Bladders are cleansed by ablution in 
 weak potash lye, subsequent washings in fresh water and 
 drying. The caoutchouc bags, mentioned at p. 216, are 
 however preferable. 
 
 * As the volume of a gas confined in tubes, or other vessels, over mercury or 
 water varies according to the pressure of the surrounding atmosphere, it becomes 
 necessary in experiments on gases to observe the baroinetric pressure, or the 
 height of the mercurial column in the barometer, at the time the volume of the 
 gas is observed. Every laboratory ought, therefore, to be provided with a baro- 
 meter, which should either be a good syphon-barometer or a cistern-barometer, 
 in which the mercury of the cistern may be brought to the same level before 
 observing the height of the column. The latter is generally read off in a scale 
 divided into inches, tenths, and hundredths of inches. As the height of the' 
 mercurial column varies according to the temperature, a correction must be 
 made for the temperature of the mercury in the barometer, which, for this pur- 
 pose, is furnished with a thermometer to be observed at the same time. 
 
272 
 
 CORRECTION FOR PRESSURE AND TEMPERATURE. 
 
 When the filled receiver is to be removed from the trough 
 for further essays with the gas, it should be gently slid off 
 
 Fig. 250. 
 
 the shelf into a flat-bottomed plate containing just enough 
 water or mercury to seal the mouth. 
 
 Correction for Pressure. — The pressure of the atmosphere 
 at the level of the sea is equivalent to 15 pounds upon each 
 square inch of the earth's surface, and is capable of support- 
 ing a column of water 32 feet high, and one of mercury 30 
 inches. The standard pressure, therefore, by which^ the va- 
 riations at different levels, and indeed at the same level, from 
 some unknown causes, are estimated, is thirty inches. 
 
 "The following is the rule for calculating the volume which 
 a gas should possess at one pressure from its known volume 
 at another pressure. As the pressure to which the gas is to 
 be reduced is to the observed pressure, or height of the baro- 
 meter, so is the observed volume to the volume required. Thus, 
 suppose a volume of gas has been observed at 120 cubic 
 inches, when the barometer is standing at 28.8 inches, we 
 find its real volume at the normal pressure, thus : 
 
 "As 30 : 28.8 : : 120 : 115.2 = the volume which the gas 
 would occupy at 30 inches barometer ; or, if the barometer 
 at the time of the experiment stands at 30.6 then 
 
 "As 30 : 30.6 : : 120 : 122.4 = the volume which the gas 
 would occupy at 30 inches barometer. When the correction 
 of a gas is to be made both for temperature and pressure, the 
 reduction is first made for temperature, and the corrected 
 volume is afterwards reduced according to the pressure." 
 
DISTILLATION IN VACUO. 273 
 
 a Corrections for Temperature. — According to the recent 
 experiments of Regnault, it appears that a volume of gas 
 expands by heat 4igth of its bulk for each degree of Fahr., 
 and calling the volume of a gas at 0° Fahr. unity, its volume 
 at any higher temperature is found by the formula 1 + 
 
 — ^^r — '- The determination of the volume of a gas at 
 459 
 
 one temperature from its known volume at another tempera- 
 ture may be attained by the following formula : — 
 
 " Let t be the temperature Fahr. at which the volume of gas 
 is observed, t' the temperature to which it is to be reduced, x 
 the observed volume at t^ and x' the volume at t' required. 
 
 Then X' - (M^jL05 
 inen x - 459 ^ ^ . 
 
 ^'Example. — Suppose the balloon to be filled with a gas at 
 the temperature of 50°, and that it has been previously as- 
 certained that its content is exactly 50 cubic inches. The 
 above formula enables us to calculate the real volume of the 
 gas at the normal temperature, thus: 
 
 (459 4- 60) X 50 
 
 459 + 50 - ^^'^^^' 
 
 so that we actually have in the globe 50.982 cubic inches of 
 gas, and our calculation for specific gravity must be made 
 accordingly. 
 
 '' Suppose, however, that the temperature of the gas is 70°, 
 or 10° above the normal temperature, we have then less than 
 500 cubic inches present, for 
 
 ( 459 -f 60) X 50 
 
 459 4-70 - ^^-^^^^ 
 
 and our calculation must be made accordingly." 
 
 Distillation in vacuo. — This kind of distillation is resorted 
 to for the production or purification of many volatile matters 
 which are alterable in the air or in aqueous vapor. Retorts 
 drawn out at their beak into a very narrow opening, or glass 
 tubes, fashioned over the blow-pipe flame to suit the process, 
 are the vessels commonly employed. After the vessel is 
 charged, heat is applied to the bulb portion, and as soon as it 
 becomes filled with vapor and all air is expelled, the tube 
 should be heated over a lamp. After the annealing of the 
 
274 DRY DISTILLATION. — LUTES. 
 
 closed end, it, being intended for the reception of the distillate, 
 should be exposed to the influence of cold while the process 
 is being conducted. If the retort is used, the receiver with 
 which it is connected must be warmed over the sand bath, 
 and in delicate experiments exhausted bj means of the syringe, 
 Fig. 244, or air-pump. Fig. 32. 
 
 Dry Distillation. — The distillation of a solid alone and 
 without contact with liquid of any kind is called dry or de- 
 structive distillation. The process is resorted to for the decom- 
 position of certain bodies more particularly organic, and their 
 resolution into new compounds by an interchange of elements. 
 The products are generally liquid and gaseous, consequently 
 the arrangement of the apparatus must be with a view to the 
 preservation of both, the means for which have been already 
 mentioned. Dry distillation requires a high heat and conse- 
 quently very refractory vessels which must be kept closed. 
 As examples, citric acid, by this process may be converted 
 into carbonic acid and oxide, acetone, aconitic acid, and 
 water ; fatty bodies modified into new substances and resins 
 transformed into oily liquids and gaseous carbohydrogens. 
 
 In the dry distillation of nitrogenized bodies, the resultant 
 products are complex, and contain nitrogen, ammonia, cyano- 
 gen, &c. For instance, indigo yields carbonate and prussiate 
 of ammonia and kyanole. 
 
 In the arts, the dry distillation of wood furnishes charcoal, 
 pyroligneous acid and pyroxylic spirit and creasote and tar; 
 and that of bituminous coal and fat, illuminating gas. 
 
 CHAPTER XVIII. 
 
 LUTES. 
 
 In all combinations of two or more pieces of apparatus or 
 parts of them, there is a necessity, in chemical operations 
 generally, of some means of hermetically closing the inter- 
 stices of their joints so as to protect the enclosure from all 
 outward communication. This is particularly requisite in 
 SUBLIMATION, DISTILLATION and Other heating operations, and 
 
LUTES : — CAOUTCHOUC, BLADDER, FLAXSEED. 275 
 
 indeed in all experiments with gases and liquids, wherever 
 it is desired to confine the volatilized particles within the 
 vessels and prevent their escape into the atmosphere and con- 
 sequent loss. 
 
 To accomplish these ends we make use of lutes, which must 
 vary in composition and mode of application with the material 
 and construction of the apparatus, the temperature at which 
 it is to be heated, and the nature of the generated products. 
 
 Caoutchouc. — This substance, in sheets, is particularly use- 
 ful for forming flexible tubes by which joints may not only be 
 rendered hermetical but also flexible. For delicate apparatus 
 it is particularly applicable even at high temperatures. The 
 tubes are made as directed at p. 216, and tied above and 
 below the joint as at x, Fig. 166. Sometimes India rubber is 
 replaced by muslin, payed over after its adjustment around 
 the joints, with a paste made by the mixture of caoutchouc 
 and spirits of turpentine. 
 
 Bladder. — Bladder well cleansed and divided into strips 
 answers very well to a limited extent. For example, when 
 moistened and coated with white of egg or solution of bone 
 glue or of isinglass, it forms an excellent covering for the 
 joints of retorts, tubes and the like, to the surfaces of which 
 it adheres tenaciously. When, however, the contained in- 
 gredients generate corrosive vapors, and so rapidly as to strain 
 the apparatus, the bladder is unserviceable. 
 
 Flaxseed Lute. — Flaxseed meal mixed to the consistence 
 of a paste with water, milk, lime-water, or starch paste. This 
 lute is very manageable and impermeable, but does not with- 
 stand a heat greater than about 500°. 
 
 If just the sufficient quantity of water be added to quick- 
 lime to reduce it to a dry powder, and that is mixed well and 
 rapidly with white of egg diluted with its own volume of 
 water, and the mixture spread immediately upon strips of linen 
 and applied to the part, which is then sprinkled with quick- 
 lime, a good cement is made. Instead of white of Qgg^ lime and 
 cheese may be used, or lime with weak glue water or blood. 
 This lute dries very rapidly, becoming very hard, and adher- 
 ing strongly to the glass ; but its great inconvenience is the 
 want of flexibility. 
 
 In spirituous distillations, the joints of the apparatus may 
 be closed very readily and eff'ectually by a stifi" paste of equal 
 weights of whiting and flaxseed meal, mixed with water. Wo 
 
276 lutes: — lime, plastic, kesinous. 
 
 have found this lute invaluahle notwithstanding its want of 
 flexibility. It is the most easily made and /most cleanly of all 
 lutes, and when the pressure of the contained vapor is con- 
 siderable, it can be covered with strips of bladder soaked in 
 solution of bone glue. 
 
 Lime and Bone Glue. — Freshly slacked lime made into a 
 thick paste with a strong solution of bone glue, makes an 
 adhesive lute very applicable for closing the joints of vessels 
 which are to be subjected to high heats, as, for example, those 
 in which the distillation of lime and sal ammoniac for the 
 production of gaseous ammonia is conducted. 
 
 Plaster of Paris. — Calcined gypsum made into a paste 
 with glue or starch water, answers the same purposes as the 
 above. When covered with strips of bladder it is rendered 
 entirely impermeable by gases. A coating of oil or of a 
 mixture of oil and wax has the same effect as the bladder, 
 and the lute will then stand a dull red heat. 
 
 Plastic lute, is made by dissolving melted caoutchouc in 
 hot linseed oil, adding finely powdered pipe clay and knead- 
 ing the whole together into a homogeneous mass. The longer 
 it is kneaded the better is its quality, and to prevent its hard- 
 ening the caoutchouc should not be in deficient proportion. 
 If it should become hard by keeping, it may be softened by 
 kneading with a little spirits of turpentine. 
 
 This lute closes the joints without hardening, and can be 
 removed at any time during the operation, to allow a change 
 in the position of the parts of the apparatus. 
 
 For the distillation of acids or other corrosive vapors, it is 
 very applicable. 
 
 Soft cement is prepared by fusing yellow wax with half its 
 weight of crude turpentine and a little Venetian red, in order 
 to color it. It is very flexible, and takes any desired form 
 under the pressure of the fingers. It is extremely useful at 
 common temperatures for tightening tubes in cork, and as a 
 coating for rendering corks impermeable to gases. 
 
 Resinous^ or hard cement, is made by fusing together at 
 the lowest possible temperature, 1 part of yellow wax and 5 
 or 6 of resin, and then adding gradually, 1 part of red ochre, 
 or finely powdered brickdust, (plaster of Paris succeeds very 
 well,) and then raising the temperature to 212° at least, until 
 no more froth arises, or agitation takes place, and stirring it 
 continually until cold. This cement is employed in a hot 
 
LUTES : — GLASS, IROX, FIRE. 277 
 
 state, and is very much used for fixing brass caps, &c., to 
 air jars, and as an impermeable coating for the interior of 
 wooden vessels. 
 
 Lute for joining Glass and Steel. — A saturated solution 
 of mastic in alcohol, mixed with a solution of isinglass in 
 dilute spirits, to which is added a small portion of galbanum 
 or ammoniac, is an excellent cement for joining glass to glass 
 or glass to steel. The mixture must be kept in a well-stopped 
 bottle, and be always warmed previous to use. 
 
 Hover (Phila.) makes an excellent cement, which answers 
 the purposes of the above, and is very useful in the labora- 
 tory for mending broken vessels for dry operations. 
 L Lute for joining Orueihles. — A mixture of fine clay and 
 i ground bricks kneaded into a paste with water, holding in 
 " solution one-tenth of borax, answers admirably for luting the 
 joints of superposed crucibles. An excellent lute for this 
 purpose and also for metallic subliming vessels, is finely pow- 
 dered Stourbridge clay, containing a little sal enixum, and 
 made into a stifi" paste with water. 
 
 Iron Cement. — This mixture is used for making permanent 
 joints generally between surfaces of iron. Clean iron borings 
 or turnings are to be slightly pounded so as to be broken but 
 not pulverized ; the result is to be sifted coarsely, mixed with 
 powdered sal-ammoniac and sulphur, and enough water to 
 moisten the whole slightly. The proportions are, 1 sulphur, 
 2 sal ammoniac, and 80 iron. No more should be mixed 
 than can be used at one time. 
 
 Fire Lute. — The best fire lute is that employed by Mr. 
 Parker, and is composed of good clay 2 parts, sharp washed 
 sand 8 parts, horse-dung 1 part. These materials are to be 
 intimately mixed; and afterwards, the whole is to be tho- 
 roughly tempered, like mortar. Mr. Watt's fire lute is an 
 excellent one, but is more expensive. It is made of finely 
 powdered Cornish (porcelain) clay, mixed to the consistence 
 of thick paint, with a solution of borax, in the proportion of 
 two ounces of borax to a pint of hot water. 
 
 Fat lute is prepared by mixing dry clay, in a fine powder, 
 with drying oil, so that the mixture may form a ductile paste. 
 It should be kept under cover, preferably in a greased blad- 
 der. When this paste is used, the part to which it is applied 
 ought to be very clean and dry, otherwise it will not adhere. 
 This lute is adhesive, and stands a pretty high heat, but 
 
278 LUTE FOR COATING FIRE VESSELS. 
 
 requires to be fastened down vdth. strips of bladder. Its 
 greatest disadvantage is the diflScultv of stopping holes which 
 may be blown through it by escaping vapor. 
 
 tead and Oil Lute, — Red lead mixed with boiled linseed 
 oil is excellent for sealing the joints of steam-vessels. It 
 hardens readily and bears a high heat. 
 
 Litte for coating Fire Vessels. — Faraday gives the follow- 
 ing directions for luting iron, glass, or earthenware retorts, 
 tubes, &c., for furnace operations. "\Mien the lute has to 
 withstand a very high temperature, it should be made of the 
 best Stourbridge clay which is to be made into a paste, vary- 
 ing in thickness according to the opinion of the operator. The 
 past« should be beaten until it is perfectly ductile and uniform, 
 and a portion should then be flattened out into a cake of the 
 required thickness, and of such a size as shall be most man- 
 ageable with the vessel to be coated. If the vessel be a retort 
 or flask, it should be placed in the middle of the cake, and 
 the edges of the latter raised on all sides, and gradually 
 moulded and applied to the glass ; if it be a tube, it should 
 be laid on one edge of the plate, and then applied by rolling 
 the tube forward. In all cases, the surface to be coated should 
 be rubbed over with a piece of the lute dipped in water, for 
 the purpose of slightly moistening and lea%'ing a little of the 
 earth upon it ; if any part of the surface becomes dry before 
 the lute is applied, it should be re-moistened. The lute should 
 be pressed and rubbed down upon the glass, successively from 
 the part where the contact was first made to the edges, until 
 all air bubbles are excluded, and an intimate adhesion efiected. 
 When one cake of lute has been applied, and is not large enough 
 to cover the whole required surface, another must be adapted 
 in a similar manner. Great care must be taken in joining the 
 edges, for which purpose it is better to make them thin by 
 pressure, and also somewhat irregular in form, and if at all 
 dry they should be moistened with a little soft lute. The 
 general thickness may be about one-quarter to one-third of 
 an inch. 
 
 Being thus luted, the vessels are afterwards to be placed 
 in a warm situation, over the sand-bath or near the ash-pit, 
 or in the sun's rays. They should not be allowed to dry 
 rapidly or irregularly, and should be moved now and then to 
 change their positions. 
 
 To prevent cracking during desiccation, and the consequent 
 
MODE OF APPLYING LUTES. 279 
 
 separation of the coat from the vessel, some chemists recom- 
 mend the introduction of fibrous substances into the lute, so 
 as mechanically to increase the tenacity of its parts. Horse- 
 dung, chopped hay and straw, horse and cow-hair, and tow 
 cut short are amongst the number. "Wlien they are used, they 
 should be added in small quantity, and it is generally neces- 
 sary to add more water than with simple lute, and employ 
 more labor to ensure a uniform mixture. It is best to mix 
 the chopped material with the clay before the water is put to 
 it, and upon adding the latter, to effect the mixture, at first 
 by stirring up the mass lightly with a pointed stick or fork ; 
 it will then be found easy by a little management, to obtain a 
 good mixture without making it very moist. 
 
 The luting ought to be made as dry as possible, consistent 
 with facility in working it. The more wet it is, the more liable 
 to crack in drying, and vice versa, 
 
 Mr. Willis recommends, when earthenware retorts, &c., are 
 to be rendered impervious to air, the following coating. One 
 ounce of borax is to be dissolved in half a pint of boiling 
 water, and as much slacked lime added as will make a thin 
 paste. This composition is to be spread over the vessel with 
 a brush, and when dry, a coating of slacked lime and linseed 
 oil is to be applied. This will dry sufficiently in a day or two, 
 and is then fit for use. 
 
 Cement for Labels. — Gum tragacanth boiled with hot water 
 makes the most adhesive paste for securing labels upon glass 
 or other smooth surfaces. The addition of a few drops of oil 
 of turpentine retards its decomposition and keeps it unaltered 
 for a long time. 
 
 Mode of applying Lutes. — Lutes are applied whilst soft, 
 being adjusted to the joints by the hand. As they become 
 dry, occasional compression with the fingers is necessary to 
 render them compact. So also when any leaks occur they 
 must be closed with fresh portions of lute smeared over and 
 pressed in by the end of the thumb. When bladder or muslin 
 is to be pasted over lute, the joint made with the latter must 
 first have dried. 
 
 When the operation is finished and the apparatus is to be 
 disconnected, remove the lute first with the hands. If, as is 
 often the case in the use of hard lutes in fire processes, they 
 adhere tenaciously, then the use of a knife, or when the ves- 
 sels are metallic, a chisel becomes necessary. 
 
280 SOLUTION. 
 
 CHAPTER XIX. 
 
 SOLUTION. 
 
 When a substance added to a liquid is wholly or partially 
 taken up by that liquid, it is said to be soluble therein. The 
 liquid employed is termed the solvent, and its combination 
 with the dissolved particles, a solution; and if the liquid has 
 exerted its solvent power to the fullest extent, then the solu- 
 tion which it forms is said to be saturated because it can hold 
 no more. 
 
 The variable degree of solubility in different liquids serves 
 as a distinctive characteristic of bodies, particularly those 
 which are solid. 
 
 Solution is either wholly mechanical, or else chemico-me- 
 chanical. In the first case it is a molecular division of a body, 
 or, in other words, a diffusion of its particles in an appropriate 
 liquid without any alteration of its original properties, save 
 as to form and cohesion. Thus, for example, an aqueous 
 solution of sugar or salt yields the whole of its charge by 
 EVAPORATION, and one of sulphate of lime by the addition of 
 alcohol, in which it is insoluble. Ethereal or spirituous solu- 
 tions deposit their dissolved matter by distillation or crys- 
 tallization; and some other kinds, that of gutta-percha, in 
 chloroform, for instance, by precipitation with ether or 
 alcohol. When the dissolved particles are thus recoverable 
 again in an unaltered state, chemically considered, their solu- 
 tion may be styled simple. 
 
 In the second case chemico-mechanical solution, in contra- 
 distinction to that which is purely mechanical, is a process 
 requiring the modification of a body by chemical action pre- 
 vious to its solution. Thus, for example, copper, iron, or any 
 other base or acid, insoluble in the ordinary solvents, may be 
 readily taken up by liquid acids or bases. But the liquid 
 holds in solution a newly formed body entirely dissimilar to 
 the original substance in properties, as appears when it is 
 separated. In this, therefore, consists the difference between 
 
SOLUTION : — NEUTRALIZATION. 281 
 
 a simple or mechanical and a chemico-mechanical solution. 
 As examples of this latter, iron may be dissolved in dilute 
 sulphuric acid, but in the act is transformed into copperas : — 
 alkalies are taken up by acids, but become ialtered to salts; 
 and oil in being dissolved by potassa solution is changed into 
 soap. Hence it is that the chemical reaction is a preliminary 
 step requisite to promote simple solution. The point of satu- 
 ration in chemical solution is that at which the two bodies, 
 invariably of opposite properties, have combined in propor- 
 tions adequate to neutralization. 
 
 There are some exceptions to the above, which refer to 
 certain instances in which acids and alkalies act as mere sim- 
 ple solvents, and without changing the original properties of 
 the dissolved substance. For example, acetic acid dissolves 
 certain phosphates and borates ; aqua ammonise takes up car- 
 mine ; potassa water the hydrated peroxide of tin, and hydro- 
 sulphuret of ammonia the deutosulphuret of iridium. 
 
 Solution is one of the most important processes in chemis- 
 try; it not only facilitates chemical reaction, but allows the 
 separation of soluble from insoluble bodies, or parts of the 
 same; and consequently the purification of the solution by 
 subsequent filtration, evaporation, and crystallization. 
 
 As regards the power of dissolving the greatest number of 
 substances, water is the first in the rank of simple solvents, 
 alcohol the next, and ether third. Then follow spirits of tur- 
 pentine, pyroxylic spirit, the volatile and fixed oils, chloroform, 
 and a host of other liquids suitable to particular substances. 
 Of the alkalies, aqua ammonise or potassa are most used ; the 
 former preferably, because of its volatility and that of most 
 of its salts. All of the common acids are employed, though 
 some few only are of general application : such as the muriatic, 
 nitric, sulphuric, acetic, and tartaric. 
 
 When the solubility of bodies is spoken of, it is in reference 
 usually to water, that being the standard liquid. In testing 
 the solubility of a substance, it is, therefore, usual to com- 
 mence with that liquid, and if it fails, to proceed with the 
 next in order; and always, for reasons below given, trying 
 the experiment at varied temperatures, with gradually in- 
 creased quantities if necessary. 
 
 A very convenient way of testing the solubility of a sub- 
 stance is by means of a test-tube. If solid, a small portion 
 in powder is to be introduced and covered with distilled water, 
 19 
 
282 SOLUTION ; — means of facilitating. 
 
 or the solvent to be used, and repeatedly agitated by the 
 hand, the forefinger closing the mouth (Fig. 
 Fig. 251. 251) to prevent the escape of particles. If 
 
 the matter is wholly soluble there will be 
 no deposit at the bottom of the tube ; if par- 
 tially soluble the deposit will have decreased 
 in bulk ; if totally insoluble it will occupy the 
 same space as at first. To determine as to 
 the two latter results, a minute portion of 
 the supernatant liquid is decanted and eva- 
 porated in a small platinum spoon or strip of 
 window-glass over the spirit lamp, (Fig. 115;) 
 if a residue remains it indicates that matter 
 has been taken up. 
 
 When heat is required, the lamp (as at Fig. 117) afibrds a 
 convenient means of application. The procedure in such cases 
 is the same as that above directed. 
 
 Volatile matters can in this way be recognized by their 
 odor emitted at boiling temperature, or else by the taste which 
 they impart to the liquid, or by some other characteristic 
 test. 
 
 The solubility of a gas may be ascertained by passing up a 
 given volume of water, or other fluid, the solvent power of 
 which is to be determined, into a graduated tube filled with 
 mercury and inverted, and then passing in similarly measured 
 volumes of the gas. When absorption ceases, by bringing 
 the interior and exterior levels nearly even, allowing for the 
 Bmall column of water, the remaining gas subtracted from the 
 whole amount introduced will show how many volumes have 
 been absorbed; knowing the relative sp. gr. of the gas and 
 water, the volumes may be calculated to weights. 
 
 1. There are certain conditions which greatly facilitate the 
 solution of substances: — 1st, comminution, which increases 
 the extent of surface ; 2d, agitation, which promotes the fre- 
 quent contact of all parts of the surface with fresh portions 
 of solvents ; 3d, the freedom from impurity of both the solvent 
 and body to be dissolved. 4th, it is also influenced by the 
 quantity and state of dilution of the solvent ; 5th, by the tem- 
 perature; 6th, by the mode in which the process is conducted. 
 
 2. Agitation is efiected by stirring with glass rods when 
 the containing vessel is open at the top. The rod should be 
 rounded at the end over the blow-pipe flame, and to prevent 
 
SOLUTION OF SOLIDS. 28S 
 
 its rolling from the table or top of the vessel upon which it 
 should be placed, may be square instead of cylindrical as is 
 usual. A very convenient and effective mode of bringing all 
 portions of the liquid successively in contact with the sub- 
 stance to be dissolved, is to place the latter in a cullendered 
 diaphragm suspended beneath the surface of the liquid. The 
 first stratum of liquid in becoming saturated increases its 
 density, and consequently descends and displaces a lower and 
 fresher portion, which being in the same way surcharged in 
 its turn, gives way to successive strata, and so the operation 
 continues until the whole of the matter, or so much as can be, 
 is taken up. This mode keeps the substance in constant con- 
 tact with new portions of liquid, and is, in fact, a kind of 
 displacement process. 
 
 When flasks or bottles are used the same effect may be 
 produced by repeated shaking. 
 
 Trituration in a mortar and alternate decantation and 
 fresh additions of the solvent greatly facilitate the solution of 
 solid substances. 
 
 3. The purity of the solvent is an important consideration, 
 for if it contain foreign matters they may impart a dissolving 
 power which is not inherent in the pure liquid, or diminish 
 that already possessed by it. Faraday makes the following 
 excellent remarks upon this subject. 
 
 *' It is necessary that the student be on his guard respecting 
 certain variations in the solubility of bodies arising from the 
 presence of other matters. He will continually find that 
 small portions of substances generally considered as insoluble 
 in water will remain in neutral solutions when some other 
 substance is present, or because of slight mutual decomposi- 
 tion; and he will also frequently find that matter usually 
 considered as readily soluble, is so with difficulty when in, 
 contact with substances with which it is not apparently in 
 combination. Thus water boiled upon muriate of potash and 
 phosphate of baryta will be found to contain more baryta than 
 if boiled alone upon the phosphate; and on the contrary, if 
 oxide of iron and alumina be precipitated together from a 
 solution, it will be found much more difficult to dissolve the 
 alumina by solution of potash than if it had been thrown down 
 alone. 
 
 " The alkaline earths are remarkably soluble in solutions of 
 sugar, and also, though to a less degree, in solutions of extract 
 
284 SOLUTION ; — influence of temperature. 
 
 and other vegetable matters : hence they are retained in solu- 
 tion at times in very unexpected situations, and might give 
 rise to much uncertainty in the appearances and characters 
 of other substances, unless the experimenter were aware of the 
 general fact. Platina is not itself soluble in nitric acid, even 
 when spongy and in its most comminuted form, but when 
 alloyed in small quantities with metals dissolved by that acid, 
 it becomes soluble with them, and in consequence appears 
 now and then in situations where it is not expected. Tartaric 
 acid or tartrates have an extraordinary power in rendering 
 many metallic oxides soluble, which are not so by other acids 
 without it; and still more in holding them in solution when 
 such substances are added as in ordinary circumstances effect 
 their separation. The oxides of bismuth, antimony, tin, and 
 titanium, are easily dissolved by acids when tartaric acid is 
 present ; and being present, ammonia no longer has the power, 
 upon its addition, of separating the oxides of iron, titanium, 
 manganese, cerium, cobalt, nickel, lead, antimony, and the 
 earths, alumina, magnesia, and yttria, from their solutions, 
 and in certain cases even potash or soda fails so to do. Great 
 advantage may be taken of this property occasionally, but 
 sometimes it is equally disadvantageous in preventing the 
 usual action of re-agents.*" 
 
 4. In regard to the quantity and state of dilution of a 
 solvent, it must be remembered that some substances require 
 more of it than others for their solution, and that it should 
 be in a greater degree of dilution. Therefore, in examining 
 the solubility of a body always commence with small quanti- 
 ties, and increase both quantity and strength gradually as 
 may be required. 
 
 5. Temperature exerts a considerable influence in the solu- 
 tion of bodies; and though in a few instances, as in the 
 solution of lime, magnesia and anhydrous sulphate of soda in 
 water, its elevation impairs the power of the solvent, yet as 
 an almost universal rule it facilitates its action. The tem- 
 perature must be adapted to the nature of the solvent and the 
 substance to be dissolved, and of the solution formed. 
 
 It may be as well to mention that the caloric rendered 
 latent at the moment of the liquefaction of a solid, which is 
 being dissolved in a liquid, causes a decrease of temperature. 
 
 * Annales de Chimie, xxiii. 356. 
 
DIFFERENT MODES OF EFFECTING SOLUTION. 285 
 
 Solution in volatile liquids should be in most cases performed 
 in the cold, and when of small quantities in narrow-necked 
 flasks.* If heat is required, especially when the vapors are 
 inflammable, a retort or covered still must be used; and if the 
 distillate is valuable, a recipient may be annexed to receive 
 as much as comes over. 
 
 6. The mode of efiecting solution varies with the substance 
 under process: Maceration, Decoction, Infusion, Diges- 
 tion, Boiling and Displacement have each and all appro- 
 priate application. 
 
 In ordinary solution the solid should be added in portions, 
 and sufficient interval allowed for the solution of those in the 
 liquid before fresh are added. In case of foaming or efierve- 
 scence an additional amount of fluid will produce a calm. 
 
 For solution in the cold or at slightly warm temperatures 
 jars of hard German glass, Fig. 252, are very ap- 
 propriate vessels. The material in powder is ^ig- 252. 
 added to the fluid in the jar and contact of fresh 
 surfaces promoted by stirring with a glass rod. 
 If the liquid solvent is volatile a glass stoppered 
 bottle is a convenient substitute for the jar, agi- 
 tation being eff^ected by shaking it to and fro. 
 
 Some volatile substances which are insoluble 
 in water under ordinary circumstances are taken 
 up by it in the state of vapor. For this purpose 
 both should be distilled together. 
 
 When solutions, emitting corrosive or dis- 
 agreeable fumes, are being made in open vessels 
 the operation should be conducted under a hood, the barrel of 
 which connects with the chimney-flue so as to ensure their 
 exit. 
 
 The containing vessels should be those which resist the ac- 
 tion of heat, acid, alkalies, and corrosive liquids. 
 
 For making saturated solutions of most substances, ebul- 
 lition is necessary. For this purpose the solid must be boiled 
 with the solvent until the latter on cooling deposits some of 
 its charge. The cooled solution is then to be filtered. 
 
 * When weighed quantities are to be transferred to a flask or other narrow- 
 mouthed vessel, the use of a funnel will prevent liability of loss. Any particles 
 that may adhere to the side of the barrel can be washed down with portions of 
 solvent. 
 
286 SOLUTION ; — op liquids ; — of gases. 
 
 Metals in their free state are dissolved one in the other by 
 
 FUSION. 
 
 Solution of Liquids. — Agitation of the liquid to be dissolved 
 together with the solvent generally effects solution. If upon 
 repose there are two layers, then all the matter is not taken 
 up, and that portion which represents the solution must be 
 separated, and a fresh quantity of the solvent added. This 
 process is to be repeated until all, or as much as possible, of 
 the liquid is dissolved. 
 
 Solution of Gases."^ — The generation and solution of gases 
 are generally simultaneous processes, and have been fully 
 treated of at p. 258. When water is used it must be distilled 
 and boiled to expel air. Viscid liquids are not less solvent 
 than others, but take up the gas much more slowly. As a 
 general rule the capacity of a liquid for a gas is proportional 
 to its rarity. (Berzelius.) 
 
 The following table (from Gray's Pharmacopoeia) of the 
 solubility of some of the salts most in use will be found very 
 convenient: — 
 
 * Liquefaction and Solidification of Gases. — Faraday has succeeded (Ann. de 
 Chim. et de Phys. 3d Series. Vol. 13, p, 121) in liquefying certain gases by 
 the combined aid of pressure and refrigeration. Among them are olefiant gas, 
 fluosilicic and hydrochloric acids. Alcohol was partially solidified in the same 
 manner. Hydriodic, hydrobroraic, and carbonic acids, sulphuretted hydrogen 
 and ammonia assumed well defined solid forms. 
 
 The author thus speaks for himself: — "I sought in the first place to obtain a 
 very low temperature, and employed for this purpose Thilorier's bath of solid 
 carbonic acid and ether, placing it however under the recipient of an air-pump. 
 By maintaining a constant vacuum, I lowered the temperature to such a degree, 
 that the carbonic acid of the bath was not more volatile than water at the tem- 
 perature of 86°, for the barometer of the air-pump stood at 28*2 inches, the 
 external barometer being at 29*4. 
 
 " This arrangement made, I joined together, by means of cork? and stop-cocks 
 some small glass and copper tubes, so that with the aid of two pumps I was 
 able to subject various gases to a pressure of 40 atmospheres, and at the same 
 time to submit them to the intense cold obtained under the air-pump, and to 
 examine the resulting effects. As I expected, the cold produced several results 
 which pressure alone would never have done, and principally in the solidifica- 
 tion of bodies ordinarily gaseous." 
 
SOLUBILITY OF SALTS. 
 
 287 
 
 THE SOLUBILITY OF SALTS. 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 
 Alcohol 
 
 
 at 60O at Boiling point. 
 
 at 60O Bt Boiling point. 
 
 ALUmNA. 
 
 Undetermined 
 
 
 Acetate of . . . 
 
 
 Ar8eniate of . 
 
 
 
 Insoluble 
 
 
 Borate of 
 
 
 
 Uncrystallizable 
 
 
 Camphorate of 
 
 
 
 0.05 
 
 
 Lactate of 
 
 
 
 Uncrystallizable 
 
 
 Muriate of 
 
 
 
 Very soluble 
 
 100 at 54i° 
 
 Nitrate of 
 
 
 
 Very soluble 
 
 100 
 
 Oxalate of 
 
 
 
 Uncrystallizable . 
 
 2.91 
 
 Phosphate of . 
 
 
 
 Insoluble 
 
 
 Seleniate of 
 
 
 
 Insoluble 
 
 
 Sulphate of . 
 
 
 
 50 
 
 
 Sulphate of, and Potash 
 
 
 5.4 133.33 
 
 
 Sulphate of, and Soda 
 
 
 100 
 
 
 Sulphite of 
 
 
 Ihsoluble 
 
 
 Tartrate of 
 
 
 Uncrystallizable . 
 
 2-91 
 
 Tartrate of, and Potash 
 
 
 Uncrystallizable 
 
 
 Tungstate of . 
 
 
 Insoluble 
 
 
 Urate and Lithate of 
 
 
 Insoluble 
 
 
 AMMONIA. 
 
 Very soluble 
 
 
 Acetate of . . . 
 
 Readily soluble 
 
 Arseniate of . 
 
 
 
 Soluble 
 
 
 Binarseniate of 
 
 
 
 Soluble 
 
 
 Arsenite of 
 
 
 
 Uncrystallizable 
 
 
 Benzoate of . 
 
 
 
 Soluble 
 
 
 Boletate of 
 
 
 
 38 
 
 
 Borate of 
 
 
 
 8^ .... 
 
 0.416 
 
 Camphorate of 
 
 
 
 1 33 
 
 
 Carbonate of (Sesqu 
 
 ) • 
 
 
 33 {Ure) 
 20 (Brande) 
 
 
 
 
 ~~ 
 
 
 Chlorate of 
 
 
 
 Very soluble 
 
 
 Chromate of . 
 
 
 
 Very soluble 
 
 
 Citrate of 
 
 
 
 Difficultly crystallizable 
 
 
 Ferrocyanide of 
 
 
 
 Very soluble 
 
 
 Formate of 
 
 
 
 Soluble 
 
 
 Hydriodate of (or I 
 of Ammonium) 
 
 odide) 
 
 Very soluble 
 
 
 Hydrocyanate of 
 
 
 Soluble 
 
 
 Hydrosulphuret of . 
 
 
 
 Very deliquescent 
 
 
 Hypophosphite of . 
 
 
 
 Soluble and deliquescent 
 
 
 Hyposulphite of 
 
 
 
 Very soluble 
 
 - 
 
 lodate of 
 
 
 
 Sparingly soluble 
 
 
 Lactate of 
 
 
 
 Uncrystallizable 
 
 
 Meconate of . 
 
 
 
 66 
 
 
 Molybdate of . 
 
 
 
 Soluble 
 
 
288 
 
 SOLUBILITY OF SALTS. 
 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 
 
 
 Alcohol 
 
 
 at 60° at Boilii 
 
 ig point. 
 
 at 60° at Boiling point. 
 
 AMMONIA. 
 
 
 
 
 
 " 
 
 J 7.5 at 80° (°i£) .900 
 
 Muriate of (or Chloride of) 
 
 36 
 
 100 
 
 Ammonium) . 
 
 ^ 
 
 ^ 4.75 do. \ bL:c J. .872 
 
 
 
 
 
 U.5 do. l^^) .834 
 
 Nitrate of 
 
 
 50 
 
 100 
 
 19.16 
 
 Oxalate of 
 
 
 4.5 
 
 40.84 
 
 
 Phosphate of . 
 
 
 25 {Brande) 
 
 
 
 Biphosphate of 
 
 
 Less soluble 
 
 
 
 Phosphite of . 
 
 
 Very soluble 
 
 
 
 Purpurate of . 
 
 
 .0066 much 
 
 more 
 
 
 Pyrolithate of . 
 
 
 Soluble 
 
 
 
 Suberate of 
 
 
 Very soluble 
 
 
 
 Succinate of . 
 
 
 Very soluble 
 
 
 
 Sulphate of 
 
 
 60 {Brande) 
 
 100 
 
 
 Sulphite of 
 
 
 100 {Ure) 
 
 
 
 Tartrate of 
 
 
 60.03 
 
 304.7 
 
 2.91 
 
 Tungstate of . 
 
 
 Soluble 
 
 
 
 ANTIMONY. 
 
 Soluble (Ure) 
 
 
 
 Acetate of 
 
 "\ 
 
 
 Benzoate of . 
 
 . 
 
 Soluble (Ure) 
 
 
 
 Tartrate of 
 
 , 
 
 Very soluble {Brande) 
 
 
 Potassio-tartrate of 
 
 • 
 
 7 
 
 50 
 
 
 , BISMUTH. 
 A 
 
 Soluble 
 
 
 
 Acetate of 
 
 '\ 
 
 
 Arseniate of . 
 
 
 Insoluble 
 
 
 
 Benzoate of 
 
 
 Soluble 
 
 . 
 
 Sparingly 
 
 Carbonate of . 
 
 
 Insoluble 
 
 
 , 
 
 Chloride of 
 
 
 Deliquescent 
 
 
 
 Nitrate of 
 
 
 Decomposed 
 
 
 
 Phosphate of . 
 
 
 Soluble 
 
 
 
 Sulphate of . 
 
 
 Decomposed 
 
 
 
 BARYTA. 
 
 A 
 
 5 at 50° 10 at 212^ 
 88 96 
 
 
 Acetate of 
 
 ^\ 
 
 • 
 
 Antimoniate of 
 
 
 Insoluble 
 
 
 
 Antimonite of . 
 
 
 Slightly 
 
 
 
 Arseniate of . 
 
 
 Insoluble 
 
 
 
 Arsenite of 
 
 
 Difficultly 
 
 
 
 Benzoate of 
 
 
 Soluble 
 
 
 
 Borate of 
 
 
 Very sparingly 
 
 
 
 Camphorate of 
 
 
 Very sparingly 
 
 
 
 Carbonate of . 
 
 
 Very nearly insoluble 
 
 
 Chlorate of 
 
 
 25 
 
 
 
 Chromate of . 
 
 
 Very sparingly 
 
 
 
 Citrate of 
 
 
 Difficultly soluble 
 
 
 
 P^errocyanuret of 
 
 
 .0005 
 
 .01 
 
 
 Hydriodate of (or 1 
 of Barium) . 
 
 odide; 
 
 Very soluble 
 
 
 
SOLUBILITY OF SALTS. 
 
 289 
 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 
 ^ 
 
 
 Alcohol 
 
 
 at 60O at Boiling 
 
 point. 
 
 ai 60O at Boiling point. 
 
 BARYTA. 
 
 
 5 at 50o 10 at 212o 
 
 
 >v 
 
 
 
 
 
 
 ~> 
 
 
 Hydrosulphuret of . 
 
 
 11 
 
 50 
 
 
 Hypophosphite of 
 
 
 
 Very soluble 
 
 
 
 lodate of 
 
 
 
 .33 
 
 1.6 
 
 
 Lactate of 
 
 . 
 
 
 Soluble 
 
 
 
 Lithate of 
 
 
 
 Insoluble 
 
 
 
 
 
 
 
 ri at 80^ O ^ r-900 
 J 0.29 . . 1 * ,' .848 
 
 Muriate of (or Chloride of 
 
 } 
 
 36.8 
 
 68.5 
 
 Barium) (Anhydrous) 
 
 i 0.18 . . f 2 1 .834 
 
 
 
 
 
 1 0.09 . . J ^ ( .817 
 
 
 
 
 
 *- ^w ^ 
 
 
 
 
 
 ri.56at80o r*^ .900 
 
 Muriate of (or Chloride of 
 Barium) Cryst. 
 
 1^ 
 
 43 {Brande) 
 
 78 
 
 0.43 . . ^ .848 
 ^ 0.32 . . .< "o >.834 
 1 0.06 . . 1 ^ 
 
 Nitrate of 
 
 
 
 5 8.18 at 58.9° 
 ^35.18 at 214.97° 
 
 
 
 Oxalate of 
 
 
 
 Nearly insoluble 
 
 
 
 Phosphate of . 
 
 
 
 Insoluble 
 
 
 
 Phosphite of . 
 
 
 
 0.25 
 
 
 
 Pyrocitrate of 
 
 
 
 .066 
 
 .02 
 
 
 Sulphate of 
 
 
 
 Insoluble 
 
 
 
 Sulphite of 
 
 
 
 Insoluble 
 
 
 
 Tartrate of 
 
 
 
 Slightly 
 
 
 
 COBALT. 
 
 Soluble 
 
 
 
 r 
 Acetate of 
 
 
 
 Antimoniate of 
 
 
 Soluble 
 
 
 
 Arseniate of . 
 
 
 Insoluble 
 
 
 
 Borate of 
 
 
 Scarcely 
 
 
 
 Carbonate of . 
 
 
 Insoluble 
 
 
 
 Lactate of 
 
 
 .026 {Ure) 
 
 
 
 Muriate, or Chloride of 
 
 
 Very soluble 
 
 
 
 Nitrate of 
 
 
 Soluble 
 
 . 
 
 100 at 54^° 
 
 Oxalate of 
 
 
 Insoluble 
 
 
 
 Sulphate of . 
 
 
 4 (Brande) . 
 
 . 
 
 Insoluble 
 
 Tartrate of 
 
 
 Soluble 
 
 
 
 COPPER. 
 
 A 
 
 {Ure) 
 
 20 
 
 
 Acetate of 
 
 ^\ 
 
 
 Antimoniate of 
 
 
 
 Insoluble 
 
 
 
 Arseniate of . 
 
 
 
 Insoluble 
 
 
 
 Benzoate of . 
 
 
 
 Slightly 
 
 
 
 Borate of 
 
 
 
 Insoluble 
 
 
 
 Carbonate of . 
 
 
 
 Insoluble 
 
 
 
 Chlorate of 
 
 
 
 Soluble 
 
 
 
 Chromate 
 
 
 
 Insoluble 
 
 
 
 Citrate of 
 
 
 
 Insoluble 
 
 
 
 Ferrocyanide of 
 
 
 
 Insoluble 
 
 
 
 Fluoride of . 
 
 
 
 Soluble 
 
 
 
290 
 
 SOLUBILITY OF SALTS. 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 ^ 
 
 Alcohol 
 
 
 ai 60O at Boilins: point. 
 
 at 60O at Boiling point. 
 
 COPPER. 
 
 
 
 >v. 
 
 12 
 
 
 Formate of . . . 
 
 
 Hyposulphite of 
 
 Soluble 
 
 
 Muriate, or Chloride of . 
 
 Soluble 
 
 100 at 176'' 
 
 Dichloride of . 
 
 Nearly insoluble 
 
 
 Nitrate of . . . 
 
 Deliquescent 
 
 
 Oxalate of . . . 
 
 Soluble ? 
 
 
 and Ammonia 
 
 Soluble! 
 
 
 and Potassa . 
 
 Soluble? 
 
 
 and Soda 
 
 Insoluble 
 
 
 Phosphate of . . . 
 
 Insoluble 
 
 
 Subnitrate of . 
 
 Insoluble 
 
 V 
 
 Sulphate of . . . 
 
 25 60 
 
 
 Disulphate of . 
 
 Insoluble 
 
 
 Trisulphate of 
 
 Insoluble 
 
 
 Sulphite of Protoxide 
 
 Insoluble 
 
 
 Sulphate of and Potassa . 
 
 Soluble 
 
 
 and Ammonia 
 
 Soluble 
 
 
 Ammonio Subsulphate 
 
 66.6 
 
 
 Tartrate of . . . 
 
 Soluble 
 
 
 Bitartrate of . . . 
 
 Less soluble 
 
 
 Tartrate of and Potassa . 
 
 Soluble 
 
 
 GOLD. 
 
 Soluble 
 
 
 Perchloride of . 
 
 
 Protochloride of 
 
 Soluble 
 
 
 IRON. 
 
 Soluble 
 
 
 ( ^ 
 Acetate (Prot.) 
 
 
 Acetate (Per.) . 
 
 Uncrystallizable 
 
 
 Antimoniate of 
 
 Insoluble 
 
 
 Arseniate of (Prot.) . 
 
 Insoluble 
 
 
 Arseniate of (Per.) . 
 
 Insoluble 
 
 
 Benzoate of . . . 
 
 Insoluble 
 
 
 Borate of . . . 
 
 Insoluble 
 
 
 Citrate (Proto.) 
 
 Soluble 
 
 
 Citrate (Bi proto.) . 
 
 Sparingly soluble 
 
 
 Citrate (Per.) . 
 
 ( Very sol uble and uncrys- ) 
 \ tallizable \ 
 
 
 Ferrocyanide (Prussian Blue) 
 
 Insoluble 
 
 
 Fluoride of . . . 
 
 Insoluble 
 
 
 Gallate of Peroxide of . 
 
 Insoluble 
 
 
 Hyposulphite of 
 
 Soluble 
 
 
 Lactate of Protox. of 
 
 Scarcely 
 
 
 Molybdate of Protox. of . 
 
 Insoluble 
 
 
 Protochloride of 
 
 Soluble 
 
 
 Perchloride of 
 
 Very soluble 
 
 100 at 1760 
 
 Nitrate of Protoxide of . 
 
 Uncrystallizable 
 
 
 Nitrate of Peroxide of 
 
 Very soluble 
 
 
 Oxalate of Protoxide of . 
 
 Soluble 
 
 
 Oxalate of Peroxide of . 
 
 Scarcely 
 Insoluble 
 
 
 Phosphate of . 
 
 
SOLUBILITY OF SALTS. 
 
 ^91 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 ^ 
 
 
 Alcohol 
 
 A 
 
 
 at 60O at Boiling: point. 
 
 at GOO at Boiling point. 
 
 IRON. 
 
 Nearly insoluble 
 
 
 
 Phosphate of Peroxide of 
 
 
 Superphosphate of . 
 
 Nearly insoluble 
 
 
 
 Succinate of Peroxide of 
 
 Insoluble 
 
 
 
 Sulphate of (Cryst.) 
 
 76.238 (Brande) 
 
 333.3 
 
 
 Sulphate of (dry) 
 
 
 
 
 Persulphate of 
 
 Uncryslallizable 
 
 . 
 
 Soluble 
 
 Hyposulphite of 
 
 Uncrystallizable 
 
 
 
 Persulphate of and Potassa 
 
 Soluble 
 
 
 
 Persulphate of and Am-> 
 monia ... J 
 
 Soluble 
 
 
 
 Tartrate (Proto.) of . 
 
 0.25 {Dumas) 
 
 
 
 Tartrate (Per.) of . 
 
 Soluble 
 
 
 
 Tartrate of and Potassa . 
 
 Uncrystallizable 
 
 • 
 
 Soluble 
 
 LEAD. 
 
 27 (Bostock) 
 
 29 
 
 
 Acetate (Cryst.) 
 
 12.5 (Brande) 
 
 Acetate (Anhyd.) 
 
 
 
 , , , 
 
 , 
 
 Soluble 
 
 Diacetate of . 
 
 
 
 Soluble 
 
 
 
 Antimoniate of 
 
 
 
 Insoluble 
 
 
 
 Arseniate of 
 
 
 
 Insoluble 
 
 
 
 Benzoate of . 
 
 
 
 Insoluble 
 
 
 
 Borate of 
 
 
 
 Insoluble 
 
 
 
 Carbonate of . 
 
 
 
 Insoluble 
 
 
 
 Citrate of 
 
 
 
 Nearly insoluble 
 
 
 
 Chlorate of 
 
 
 
 Soluble 
 
 
 
 Chloride of 
 
 
 
 3.33 {.Brande) 
 
 4.5 
 
 
 Chloride of (fused) 
 
 
 
 
 
 
 Chromate of . 
 
 
 
 Insoluble 
 
 
 
 Ferrocyanuret of 
 
 
 
 Insoluble 
 
 
 
 Gallate of 
 
 
 
 Insoluble 
 
 
 
 Iodide of 
 
 
 
 0.08 
 
 0.5 
 
 
 Hyposulphite of 
 
 
 
 Soluble 
 
 
 
 Lactate of 
 
 
 
 Soluble (Ure) 
 
 
 
 Superlactate of 
 
 
 
 Soluble 
 
 
 
 Malate of 
 
 
 
 Scarcely 
 
 
 
 Molybdate of . 
 
 
 
 Insoluble 
 
 
 
 Nitrate of 
 
 
 
 13 
 
 
 
 Dinitrate of . 
 
 
 
 ( Scarcely at 60^, but much 
 \ more so at 212° 
 
 
 Oxalate of 
 
 
 
 Insoluble 
 
 
 
 Phosphate of . 
 
 
 
 Insoluble 
 
 
 
 Phosphite of . 
 
 
 
 Insoluble 
 
 
 
 Succinate of . 
 
 
 
 Insoluble 
 
 
 
 Sulphate of 
 
 
 
 Not absolutely insoluble 
 
 
 Sulphite of 
 
 
 
 Insoluble 
 
 
 
 Tannate of 
 
 
 
 Insoluble 
 
 
 
 Tartrate of 
 
 
 
 Almost insoluble 
 
 
 
 and Pota 
 
 3sa 
 
 
 Insoluble {Berzelins) 
 
 
292 
 
 SOLUBILITY OP SALTS. 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 •«. 
 
 Alcohol 
 
 
 at 603 at Boiling point. 
 
 at 60° at Boiling point. 
 
 LIME. 
 
 (Kirwan) 
 
 
 A 
 
 
 
 1 \ 
 
 
 
 
 r2.4at80°r's ~).900 
 J 4.12 . . j c£ 1.848 
 1 4-75 . . i ^1" r.834 
 
 1^4.88. . i^'^'j.sn 
 
 Acetate of . . . 
 
 Soluble 
 
 Antimoniate of 
 
 Insoluble 
 
 
 Arseniate of . 
 
 Insoluble 
 
 
 Arsenite of . . . 
 
 Difficultly soluble 
 
 
 Benzoate of . . . 
 
 Sparingly soluble 
 
 
 Borate of . . . 
 
 Very difficultly 
 
 
 Carbonate of (Anhyd). . 
 
 Insoluble 
 
 
 Chlorate of . . . 
 
 Very soluble 
 
 Soluble 
 
 Chromate of . . . 
 
 Soluble 
 
 
 Citrate of . . . 
 
 Nearly insoluble 
 
 
 Fluoride .... 
 
 Insoluble 
 
 
 Hypophosphite of . 
 
 < Solubility nearly equal 
 \ at all temperatures 
 
 
 Hyposulphate of 
 
 40.65 (Brande) 150 
 
 
 Hyposulphite of 
 
 Very soluble 
 
 
 lodate of ... 
 
 20 100 
 
 
 Iodide of Calcium . 
 
 Deliquescent 
 
 
 Malate of . . . 
 
 .66 1.53 
 
 
 Molybdate of . 
 
 Insoluble 
 
 r200 at 32° 
 
 J 400 at 60° 
 
 
 Muriate, (or Chloride of) 
 Calcium) . . J 
 
 
 1 almost any quantity at 
 
 
 
 i 220° 
 
 
 Nitrate of . . . 
 
 S5 .... 
 
 161.66 
 
 Oxalate of 
 
 Insoluble 
 
 
 Phosphate of . 
 
 Insoluble 
 
 
 Biphosphate of 
 
 Soluble 
 
 
 Subphosphate of 
 
 Almost insoluble 
 
 
 Succinate of . 
 
 Difficultly soluble 
 
 
 Sulphate of . . . 
 
 0.301 at 50° 
 
 
 Sulphite of . . . 
 
 12.5 
 
 
 Tartrate of . 
 
 ; Nearly insoluble at 60° 
 '[ but .16 at 212° 
 
 
 Tungstate of . 
 
 Insoluble 
 
 
 LITHIA. 
 
 
 
 >^ 
 
 Deliquescent 
 
 
 Acetate of . . . 
 
 
 Bicarbonate of 
 
 Slightly soluble 
 
 
 Borate of . . . 
 
 Soluble 
 
 
 Carbonate of . 
 
 1 .... 
 
 Insoluble 
 
 Chloride of Lithium 
 
 Very deliquescent 
 
 
 Chromate of . . . 
 
 Very soluble 
 
 
 Citrate of . . . 
 
 Very difficultly soluble 
 
 
 Nitrate of . . . 
 
 Very deliquescent 
 
 
 Oxalate of . . . 
 
 Very deliquescent 
 
 
 Binoxalate of . 
 
 Less soluble 
 
 
 Phosphate of . 
 
 Insoluble 
 
 
 Sulphate of . . . 
 
 Soluble 
 
 
SOLUBILITY OF SALTS. 
 
 293 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 ^ 
 
 Alcohol 
 
 
 at 60O at Boiling point. 
 
 at 60° at Boiling point. 
 
 LITIil 
 , ^■ 
 
 Tartrate of 
 
 A. 
 
 ^ 
 
 Easily soluble 
 
 
 
 
 and Potassa . 
 
 Easily soluble 
 
 
 and Soda 
 
 Easily soluble 
 
 
 MAGNESIA. 
 A. 
 
 Very soluble 
 
 
 ( \ 
 Acetate of . . . 
 
 
 Arseniate of . 
 
 
 
 Deliquescent 
 
 
 Arsenite of 
 
 
 
 Difficultly soluble 
 
 
 Benzoate of 
 
 
 
 Soluble 
 
 
 Borate of 
 
 
 
 Insoluble 
 
 
 Carbonate of . 
 
 
 
 Very slightly 
 
 
 Chlorate of 
 
 
 
 Very soluble 
 
 
 
 
 f50 547 
 
 Chloride of Magnesium . 
 
 200 (Brande) 
 
 ^'50at80O fSp.gr.j .817 
 
 ., 
 
 
 i.2125... ( Spts. j .900 
 
 Chromate of . . 
 
 Very soluble 
 
 
 Citrate of . . . 
 
 Difficultly soluble 
 
 
 Iodide of Magnesium 
 
 Soluble 
 
 
 Malate of . . . 
 
 3.56 {Brande) 
 
 
 Molybdate of . 
 
 6.66 8.35 
 
 ^Nearly insoluble in 
 
 Nitrate of . . . 
 
 100 ... . 
 
 < pure alcohol 
 (11 sp.gr. .840 
 
 Oxalate of . . . 
 
 Nearly insoluble 
 
 
 Phosphate of . 
 
 6.66 
 
 
 and Ammonia 
 
 Sparingly soluble 
 
 
 Succinate of . . 
 
 Uncrystallizable 
 
 
 Sulphate of (dry) 
 
 33.192 73.57 
 
 
 Sulphate of (cryst.) . 
 
 68.042 150.71 
 
 1 at 80° {Kirwan) 
 
 and Ammonia 
 
 Soluble 
 
 
 and Potassa . 
 
 Soluble 
 
 
 and Soda 
 
 33.3 
 
 
 Sulphite of . . . 
 
 5 
 
 
 and Ammonia 
 
 Difficultly soluble 
 
 
 Tartrate of . . . 
 
 Insoluble 
 
 
 Tungstate of . 
 
 Soluble 
 
 I 
 
 MANGANESE. 
 
 3 
 
 
 f ^ 
 Acetate of . . . 
 
 Soluble 
 
 Ammonio-chloride of 
 
 
 Soluble 
 
 
 Ammonio-sulphate of 
 
 
 Soluble 
 
 
 Antimoniate of 
 
 
 Moderately soluble 
 
 
 Arseniate of . 
 
 
 
 Insoluble 
 
 
 Benzoate of 
 
 
 
 
 Deliquescent {Brande) 
 
 
 Carbonate of 
 
 
 
 
 Insoluble 
 
 
 Chromate of 
 
 
 
 
 Soluble 
 
 
 Nitrate of 
 
 
 
 
 Very soluble 
 
 Soluble 
 
 Oxalate of 
 
 
 
 
 Insoluble 
 
 
 Phosphate of 
 
 
 
 
 Nearly insoluble 
 
 
 Succinate of 
 
 
 
 
 1 {Ure) 
 
 
294 
 
 SOLUBILITY OP SALTS. 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 ^ 
 
 Alcohol 
 
 
 at 60° at Boiling point. 
 
 at 60° at Boiling point. 
 
 MANGANESE. 
 
 
 
 >v 
 
 
 
 
 
 Sulphate of . . . 
 
 81 (Ure) 
 60 {Brande) 
 
 
 Hyposulphate of 
 
 Deliquescent 
 
 
 Sulphite of . . . 
 
 Insoluble 
 
 
 Tungstate of . 
 
 Insoluble 
 
 
 MERCURY. 
 
 
 
 TV. 
 
 0.16 (Braconnot) 
 
 
 Acetate of (Prot.) . 
 
 
 Acetate of (Per.) . 
 
 Readily soluble 
 
 
 Arseniate of . 
 
 Insoluble 
 
 
 Benzoate of . . . 
 
 Insoluble 
 
 
 Borate of . . . 
 
 Insoluble 
 
 
 Bichloride of . 
 
 6.25 {Brande) 33.3 
 
 42.6 85.2 
 
 r 10.74 at 50° 
 J Sprts. sp. gr. .915 
 ^ 43.66 at 50° 
 
 I^Sprts. sp. gr. .818 
 
 Chloride of . . . 
 
 .00833 at 212° {Dumas) 
 
 {Graham) 
 
 Chromate of . 
 
 Insoluble 
 
 
 Citrate of . . . 
 
 Insoluble 
 
 
 Bicyanuret of . 
 
 54 
 
 
 Fluoride of . . . 
 
 Soluble 
 
 
 Molybdate of . 
 
 Very sparingly 
 
 
 Nitrate (Prot.) . 
 
 (Soluble and decomposed 
 I by excess 
 
 
 Nitrate of (Per.) 
 
 Do. do. 
 
 
 Oxalate of (Proto.) . 
 
 Scarcely 
 
 
 Oxalate of (Per.) 
 
 Insoluble 
 
 
 Sulphate of (Proto.) 
 
 0.20 0.33 
 
 
 Sulphate of (Per.) . 
 
 Decomposed 
 
 
 Sulphate of (Sub.) . 
 
 .005 0.33 
 
 
 Tartrate of . . . 
 
 Insoluble 
 
 
 and Potassa . 
 
 Soluble 
 
 - 
 
 NICKEL. 
 
 
 Acetate of . . . 
 
 Very soluble 
 
 Arseniate of . 
 
 Soluble {Ure) 
 
 Carbonate of . 
 
 Insoluble 
 
 Chloride of . . . 
 
 Soluble in hot water 
 
 Nitrate of Protox. . 
 
 50 . . . . 
 
 and Ammonia 
 
 Soluble 
 
 Oxalate of . . . 
 
 Insoluble 
 
 Phosphate of . 
 
 Nearly insoluble 
 
 Sulphate of . . . 
 
 33.3 185.71 
 
 and Ammonia 
 
 25 
 
 and Potassa . 
 
 11.1 
 
 and Iron 
 
 Soluble 
 
 Tartrate of . . . 
 
 Very soluble 
 
 Soluble 
 
SOLUBILITY OP SALTS. 
 
 295 
 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 
 
 
 Alcohol 
 
 
 at 60° at Boiling point. 
 
 at 60O at Boiling point. 
 
 PLATINUM. 
 
 Soluble 
 
 
 
 Protochloride of 
 
 ^ 
 
 (Easily soluble, also in 
 I Ether 
 
 Perchloride of . 
 
 Soluble 
 
 Protochloride of 
 
 and Ammonium 
 
 1 
 
 Soluble 
 
 . 
 
 Insoluble 
 
 and Potassium 
 
 
 Soluble 
 
 . 
 
 Insoluble 
 
 and Sodium 
 
 
 Uocrystallizable . 
 
 . 
 
 Very soluble 
 
 Bichloride of . 
 
 and Ammonium 
 
 ( 
 
 Very sparingly 
 
 
 
 and Potassium 
 
 
 Very sparingly 
 
 
 
 and Sodium 
 
 
 Soluble 
 
 . 
 
 Soluble 
 
 and Barium 
 
 
 Soluble 
 
 
 
 Protonitrate of 
 
 
 Soluble 
 
 
 
 Pernitrate of . 
 
 
 Soluble 
 
 
 
 Protosulphate of 
 
 
 Soluble 
 
 
 
 Persulphate of 
 
 
 Very soluble 
 
 
 (Very soluble, also in 
 I Ether 
 
 POTASS A. 
 
 100 .. . 
 
 
 
 Acetate of 
 
 ^ 
 
 2oa 
 
 Ammonio-oxalate of 
 
 
 Soluble 
 
 
 
 Ammonio-suiphate of 
 
 
 13 
 
 
 
 Ammonio-tartrate of 
 
 
 Very soluble 
 
 
 
 Antimoniate of 
 
 
 Slightly 
 
 
 
 Antimonite of , 
 
 
 
 Soluble 
 
 
 
 Arseniate of 
 
 
 
 Uncrystallizable . 
 
 . 
 
 a.75 
 
 Binarseniate of 
 
 
 
 18.86 at 40° 
 
 . 
 
 Insoluble 
 
 Arsenite of 
 
 
 
 Uncrystallizable 
 
 
 
 Benzoate of 
 
 
 
 Very soluble 
 
 
 
 Bibenzoate of . 
 
 
 
 10 
 
 
 
 Borate of 
 
 
 
 Soluble 
 
 
 
 Camphorate of 
 
 
 
 1 
 
 25 
 
 
 Carbonate of . 
 
 
 
 100 
 
 
 
 Bicarbonate of 
 
 
 
 25 
 
 83 
 
 
 Chlorate of 
 
 
 
 6.03 60 at ISSi* 
 
 
 Chromate 
 
 
 
 48 extremely 
 
 Insoluble 
 
 Bichromate of . 
 
 
 
 10 much more 
 
 
 Citrate of 
 
 
 
 Very soluble 
 
 
 
 Columbate of . 
 
 
 
 Uncrystallizable 
 
 
 
 Ferrocyanide of 
 
 
 
 33.3 
 
 100 
 
 
 Iodide of Potassium 
 
 
 
 143 at 6.5° (G.Lussac) 
 
 Sparingly 
 
 lodate of 
 
 
 
 7.14 {Brande) 
 
 
 
 Molybdate of . 
 
 
 
 Soluble 
 
 
 
 Chloride of Potassium 
 
 
 (29.21 at 66.83° ) 
 ^59.26 at 229.28° J 
 
 ( 29.31 at 64°) 
 
 • 
 
 f2 083 
 
 1 4 62 at 80° C ° « -) .900 
 
 1.66 . . ■!&?>■ .812 
 
 10.38 . . i^j:} .834 
 
 Nitrate of 
 
 
 ; 236.45 at 207° V 
 ^285. at 238°) 
 
 • 
 
 2.083 
 
 Oxalate of 
 
 • 
 
 (50 {Ure) . 
 1 30 {Brande) 
 
 \ 
 
 ( 2.76 at 80O Sp. gr. .900 
 ( 1 . .of Sprls. .872 
 
 Binoxalate of . 
 
 
 . 
 
 {\0 Brande) {Ure 100) 
 
 
296 
 
 SOLUBILITY OF SALTS. 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 j^ 
 
 Alcohol 
 
 
 at 60° at Boiling point. 
 
 at 6OO at Boiling point. 
 
 POT ASS A. 
 
 TV. 
 
 66.66 
 
 
 Quadroxalate of 
 
 2.91 
 
 Phosphate of . 
 
 Difficultly soluble 
 
 
 Diphosphate of 
 
 Soluble in hot water 
 
 
 Biphosphate of 
 
 Very soluble 
 
 
 Hypophosphite of . 
 
 Very deliquescent 
 
 Very soluble 
 
 Hyposulphate of 
 
 [Difficultly soluble at 60° 
 '[ readily at 212° 
 
 
 Hyposulphite of 
 
 Deliquescent 
 
 
 and Silver 
 
 Difficultly 
 
 
 Succinate of . . . 
 
 Very soluble 
 
 
 Sulphate of . . . 
 
 5 10.57 at 54° 
 )26.33at214° 
 
 
 Bisulphate of . 
 
 5 50 at 40° 
 {200at220° 
 
 
 Sulphite of . . . 
 
 100 
 
 
 Tartrate of 
 
 100 ... . 
 
 0.416 
 
 Bitartrate of . . . 
 
 1.05 6.66 
 
 2.91 
 
 Tartrovinate of 
 
 10 any quantity 
 
 
 Tungstate of . 
 
 Uncrystallizable 
 
 
 Nitro-tungstate of . 
 
 {Ure) 5 
 
 
 SILVER. 
 
 Very difficultly soluble 
 
 
 Acetate of . . . 
 
 
 Arseniate of . . . 
 
 Insoluble 
 
 
 Arsenite of . . . 
 
 Insoluble 
 
 
 Borate of . . . 
 
 Difficultly soluble 
 
 
 Chlorate of . . . 
 
 25 (Chenevix) 
 
 
 Chromate of . 
 
 Very slightly 
 
 
 Citrate of . . . 
 
 Insoluble 
 
 
 Molybdate of . 
 
 Insoluble 
 
 
 Chloride of (Fused) 
 
 Insoluble 
 
 
 Nitrate of (Cryst.) . 
 
 100 200 
 
 25 
 
 Oxalate of . . . 
 
 Insoluble 
 
 
 Phosphate of . 
 
 Insoluble 
 
 
 Succinate of . . . 
 
 Soluble 
 
 
 Sulphate of . . . 
 
 1.15 
 
 
 Sulphite of . . . 
 
 Very little soluble 
 
 
 Hyposulphite of 
 
 Soluble 
 
 
 and Potassa 
 
 Difficultly soluble 
 
 
 Tartrate of . . . 
 
 Soluble 
 
 
 and Potassa . 
 
 Soluble 
 
 
 SODA. 
 
 35 150 
 
 
 Acetate of . . . 
 
 
 Arseniate of . . . 
 
 510 (Thompson) 
 125 (Ure) 
 
 ♦ 
 
 Binarseniate of 
 
 Soluble 
 
 
 and Potassa 
 
 Soluble 
 
 
 Benzoate of . . . 
 
 Very soluble 
 
 
 Biborate of . . . 
 
 8.033 50 
 
 
 Carbonate of . 
 
 50 100 
 
 
SOLUBILITY OF SALTS. 
 
 297 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 
 Alcohol 
 
 
 
 at 60O at Boiling point. 
 
 at 60O at Boiling point. 
 
 SODA. 
 
 7.6 
 
 
 
 Bicarbonate of 
 
 
 Chlorate of 
 
 
 33.3 .... 
 
 Sol. in sp. rect. 
 
 
 Chromate of . 
 
 
 Very soluble 
 
 Sparingly 
 
 
 Citrate of 
 
 
 100 or more (Brande) 
 
 
 
 Iodide of Sodium . 
 
 
 173 
 
 
 
 lodate of . 
 
 
 7.3 . 
 
 Insoluble 
 
 
 Molybdate of . 
 
 
 Soluble 
 
 
 
 Muriate of (or Chloride of) 
 Sodium) . . 5 
 
 Equally soluble at all) 
 temperatures {Berz.)^ 
 r 33.3 at 60») „, «,.,c 
 100 at 123^ J ^""^^ 
 
 (.0.5 . . i Spts. , 
 
 1.900 
 
 -.872 
 1 834 
 
 
 50 at 60° Berzel. 
 
 r 
 
 .95S 
 
 
 73 at 32°) {Gay 
 
 J 10.5at80O (Sp.gr.) 
 
 .900 
 
 Nitrate of . . . 
 
 < 173 at2l2°j Lussac) 
 
 6 . . . of 
 
 .872 
 
 
 80 at 32°i 
 
 io.38 . . ( Spts. 
 
 .834 
 
 
 22.7 at 50° I ^^^^ 
 55 at 61° > ^^'"^ 
 
 
 
 
 ^218.5 at 246"J 
 
 
 
 Oxalate of . . . 
 
 Sparingly soluble 
 
 
 
 Phosphate of . 
 
 25 50 
 
 
 
 and Ammonia 
 
 Soluble 
 
 
 
 Biphosphate of 
 
 Very soluble 
 
 
 
 Hypophosphite of . 
 
 Very soluble 
 
 Very soluble 
 
 
 Succinate of . 
 
 Soluble 
 
 
 
 Sulphate of (Cryst.) . 
 
 5 48.28 at 64° 
 • 322.12 at 91° 
 (16.73 at 64°) ,^^^, 
 )50.65at 91°[ j^^^) 
 (42.65 at 217° S ■^"««"^> 
 
 
 
 Sulphate of (dry) 
 
 Insoluble 
 
 
 Hyposulphate of 
 
 41.6 91 
 
 Insoluble 
 
 
 Bisulphate of . 
 
 50 
 
 
 
 Sulphate of and Ammonia 
 
 Soluble 
 
 
 
 Sulphite of . . . 
 
 25 
 
 
 
 Hyposulphite of 
 
 Deliquescent 
 
 Insoluble 
 
 
 Tartrate of . . . 
 
 56.37 {Thomson) 
 
 Insoluble 
 
 
 and Potassa . 
 
 20 
 
 
 
 
 
 (Sol. in sp. rect., 
 
 but 
 
 Tartrovinate of 
 
 Soluble 
 
 } sparincrly in absolute 
 
 
 
 ( alcohol 
 
 
 Tungstate of . 
 
 25 50 
 
 
 
 STRONTIA. 
 
 (0.625 at 60O) 
 • 5 at 212° 5 ^^'^^^ 
 2 50 
 
 
 
 Hydrate of . . . 
 
 
 
 Acetate of 
 
 
 Very soluble 
 
 
 
 Arseniate of . 
 
 
 Sparingly soluble 
 
 
 
 Arsenite of 
 
 
 Sparingly soluble 
 
 
 
 Borate of 
 
 
 0.76 
 
 
 
 Carbonate of . 
 
 
 0.0651 at2123 
 
 
 
 Chlorate of 
 
 
 Very soluble 
 
 SoluMe 
 
 
 Chloride of Strontium 
 
 
 50 . . . ., 
 
 Soluble 
 
 
 Chromate of . 
 
 
 Insoluble {Brande) 
 
 
 - 
 
 Citrate of 
 
 
 Soluble 
 
 
 
 20 
 
298 
 
 SOLUBILITY OF SALTS. 
 
 
 Solubility in 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 j^ 
 
 Alcohol 
 
 
 at 60O at Boiling point. 
 
 at 60O at Boiling point. 
 
 STRONTIA. 
 
 
 
 J\. 
 
 25 
 
 
 Ferrocyanuret of . 
 
 
 Iodide of Strontium 
 
 Soluble 
 
 
 lodate of ... 
 
 25 
 
 
 Nitrate of . . . 
 
 113 
 
 
 Oxalate of . . . 
 
 0.52 
 
 
 Phosphate of . 
 
 Insoluble 
 
 
 Phosphite of . 
 
 Soluble 
 
 
 Hypophosphite of . 
 
 Very soluble 
 
 
 Succinate of . . . 
 
 Soluble 
 
 
 Sulphate of . . . 
 
 0.026 at 212o 
 
 
 Hyposulphite of 
 
 20 {Gay Lussac) 
 
 Insoluble 
 
 Hyposulphate of 
 
 22.22 66.66 
 
 
 Tartrate of . . . 
 
 0.67 at 170° 
 
 
 TIN. 
 
 Soluble 
 
 
 Acetate of . . . 
 
 
 Arseniate of . . 
 
 Insoluble 
 
 
 Borate of ... 
 
 Insoluble 
 
 
 Nitrate Proto. of 
 
 Uncrystallizable 
 
 
 Nitrate Per. of 
 
 Scarcely 
 
 
 Oxalate of . . . 
 
 Soluble 
 
 
 Phosphate of . 
 
 Insoluble 
 
 
 Succinate of . . 
 
 Soluble 
 
 
 Sulphate Proto. of . 
 
 Crystallizable 
 
 
 Sulphate Per. of 
 
 Uncrystallizable 
 
 
 Tartrate of . . . 
 
 Soluble 
 
 
 and Potassa . 
 
 Very soluble 
 
 
 ZINC. 
 
 Very soluble 
 
 
 Acetate of . . . 
 
 
 Antimoniate of 
 
 Very sparingly 
 
 
 Borate of . . . 
 
 Insoluble 
 
 
 Chromate of . 
 
 Sparingly 
 
 
 Citrate of . . . 
 
 Scarcely 
 
 
 Chlorate of . . . 
 
 Very soluble 
 
 
 Chloride of . . . 
 
 Very soluble 
 
 100 at 54io 
 
 Iodide of ... 
 
 Soluble 
 
 
 lodate of . . . 
 
 Difficultly soluble 
 
 
 Lactate of . . . 
 
 2 (Ure) 
 
 
 Nitrate of . . . 
 
 Deliquescent 
 
 
 Molybdate of . 
 
 Insoluble 
 
 
 Oxalate of . . . 
 
 Nearly insoluble 
 
 
 Phosphate of . 
 
 Uncrystallizable 
 
 
 Succinate of . . . 
 
 Soluble 
 
 
 Sulphate of . . . 
 
 140 {Dumas) 
 
 
 Sulphite of 
 
 81.81 at 220^ 
 
 Insoluble 
 
 Hyposulphite of 
 
 Soluble 
 
 Soluble 
 
 Sulphate of and Nickel . 
 
 33.33 
 
 
 Tartrate of . . . 
 
 Difficultly soluble 
 
 
 Tartrovinate of 
 
 Soluble 
 
 Sparingly soluble 
 
 Trisulphate of 
 
 Soluble 
 
 
SOLUBILITY OF ACIDS, BASES, ETC. 
 SOLUBILITY OF ACIDS, BASES, &c. 
 
 299 
 
 
 Solubihty 
 
 ill 100 parts Water 
 
 Solubility in 100 parts 
 
 Name of Salt. 
 
 
 
 
 Alcohol 
 
 
 at GOO 
 
 at Boilinf? point. 
 
 at 60O at Boiliii": point. 
 
 ACID. 
 
 
 
 
 
 A. 
 
 
 
 
 
 Arsenious 
 
 
 Vitreous . 
 
 1.7S 
 
 (Graham' 
 
 9.68 
 
 
 Opaque . 
 
 2.9 
 
 (Graham) 11.47 
 
 
 Benzoic .... 
 
 .50 
 
 
 
 
 Boracic .... 
 
 3.9 
 
 
 33.3 
 
 20 at 176^ (Henry) 
 
 Citric .... 
 
 133.33 
 
 
 200 
 
 Soluble 
 
 Gallic .... 
 
 5 
 
 
 33.33 
 
 
 Oxalic (Cryst.) . 
 
 11.5 
 
 
 
 
 Succinic (Cryst.) 
 
 4 
 
 
 33.33 
 
 74 at 1763 
 
 Tartaric .... 
 
 150 (Brande) 
 
 200 
 
 Soluble 
 
 Brucia .... 
 
 .1177 
 
 
 0.2 
 
 Soluble 
 
 Cinchonia 
 
 Insoluble 
 
 0.04 
 
 Partially soluble 
 
 Morphia .... 
 
 Nearly 
 
 insoluble 
 
 1 
 
 4. 
 
 Quinia .... 
 
 Nearly 
 
 insoluble 
 
 0.5 
 
 Very soluble 
 
 Strychnia 
 
 0.04 {Graham) 
 
 0.15 
 
 C5. sp. grr. of spts. 870 
 X (Duflos). 
 75 at 176* 
 
 Camphor 
 
 0.229 
 
 . 
 
 . 
 
 Cane Sugar 
 
 200 
 
 • 
 
 • 
 
 
 CHAPTER XX. 
 
 MACERATION. — INFUSION. — DECOCTION. — DIGESTION. — BOIL- 
 ING. — DISPLACEMENT. 
 
 Maceration. — The soaking or steeping of a substance in 
 a liquid, at the ordinary temperature, is termed maceration. 
 It is almost exclusively applicable to organic substances, 
 being most frequently resorted to as a means of hastening and 
 facilitating the after solution of the extractive parts of hard, 
 compact or impervious wood, roots, stems and leaves by the 
 more active methods of displacement or of ebullition. It 
 is employed when the soluble principles are alterable by 
 heat: and is also made use of to effect the solution of a sub- 
 stance containing several principles, the solubility of which 
 varies with the temperature applied, as it leaves those which 
 
300 SOLUTION. — INFUSION. — DECOCTION. 
 
 are not taken up in the cold to be acted upon by the aid of 
 heat. Thus, for example, in the treatment of most vegetable 
 substances, starch which is generally present and is only solu- 
 ble at the boiling point of water, will remain untouched, while 
 all other principles soluble without heat can be separated 
 from it. 
 
 The mode of performing the process is merely to place the 
 solvent and the substance to be dissolved, together in a vessel, 
 and to allow them to remain a longer or shorter time, accord- 
 ing to the nature of the substance. For ordinary purposes a 
 loosely covered pan of blue stone-ware is very convenient. 
 In delicate operations a beaker glass. Fig. 254, or solution jar, 
 Fig. 252, is more appropriate. When the solvent is volatile, 
 a wide mouthed stoppered bottle may be used. 
 
 Infusion. — This process is likewise applicable almost solely 
 to organic substances. Instead, however, of the solid remain- 
 ing in contact for a length of time with the solvent, the latter 
 is first heated to boiling and then poured upon the former. 
 After having cooled, the liquid may be decanted or pressed 
 out— p. 320, Fig. 276. 
 
 This mode is used for the exhaustion of flowers, leaves, 
 roots, seeds and other substances of delicate texture, which 
 are easily penetrable and readily yield their soluble matters ; 
 and especially for the purpose of extracting volatile ingre- 
 dients. The heat applied to the solvent increases its energy; 
 but as the material is only in contact for a limited time, the 
 interval between the commencement and completion of the 
 operation is not sufficient to affect the material or solution, 
 even though one or more of its components are alterable by 
 heat. 
 
 In pharmaceutical operations, this process is generally con- 
 ducted in cast iron flask-shaped vessels with handles, ena- 
 melled on the inside and fitted with a tight cover, which is to 
 be kept in its place from the addition to the cooling of the 
 solvent. For small operations, a beaker glass covered with 
 a capsule, or a yellow earthenware stew pan with lip and 
 cover, such as can be had at the crockery shops, are admirably 
 adapted. 
 
 Decoction. — This mode of solution, which is so important 
 to the Pharmaceutist, is chiefly employed for the purpose of 
 exhausting those vegetable substances, the components of 
 
SOLUTION BY DIGESTION. 301 
 
 which will not readily yield to other means. It is merely an 
 extension of the last process, and consists in that contact 
 of the material to be dissolved with a hot solvent in a covered 
 vessel, which is continued until all soluble matter is taken up. 
 Most volatile matters are expelled by decoction; but those 
 which are insoluble, save by prolonged action of heat, are 
 dissolved or suspended, as it were, by favor of other principles 
 present. 
 
 Decoction is only used with liquid solvents which are not 
 decomposable by heat. 
 
 In all of the preceding processes, as well also in others in 
 
 Fig. 253. 
 
 which solid vegetable matter is subjected to the solvent action 
 of liquids, the cullendered ladle, Fig. 253, of tinned wire is 
 most useful for transferring the residue to the press, Fig. 276, 
 for removal of any retained liquid. 
 
 Digestion. — This mode of solution differs from maceration 
 in requiring the assistance of heat, and consists in exposing a 
 body to the prolonged action of a liquid in a covered vessel, at 
 any temperature between 90° F. and several degrees less than 
 the boiling point of the solvent. The method of heating 
 varies with circumstances, and can be by a gentle fire, or by 
 the sand, steam, water or saline Bath, as the nature of the 
 operation requires. 
 
 In analysis, glass or platinum vessels are used; but in less 
 important operations those of other materials are more con- 
 venient and economical. 
 
 A very important advantage of digestion is, that it allows 
 the perfect solution of all soluble portions of a substance, 
 without modifying the nature of the solvent. It is especially 
 useful for the decomposition of ores, minerals and other sub- 
 stances difficultly acted upon by acids or other solvents, and 
 also for effecting the synthesis of compounds requiring a long- 
 continued heat. Moreover, it is very available in preparing . 
 alcoholic and aqueous solutions, medicinal oils and other phar- 
 maceutical products. 
 
302 
 
 SOLUTION BY DIGESTION. 
 
 Fig. 254. 
 
 In analytic operations, digestion is performed in beaker 
 glasses. These are bell-shaped vessels, 
 Fig. 254, of Bohemian glass, and uniformly 
 thin throughout, so as to support a con- 
 siderable elevation of temperature. The 
 glass must be well annealed, hard and free 
 from lead, so as to resist the action of 
 acids. These vessels come in nests of dif- 
 ferent numbers. Their size varies gra- 
 dually upwards from an ounce in capacity 
 to a gallon. 
 
 The substance to be acted upon, in a 
 state of fine powder, is transferred to the 
 glass, which must be perfectly clean, and is then mixed with 
 the proper quantity of acid or other liquid by shaking the 
 glass after the addition, or by the use of a glass stirrer, 
 taking care, however, in this last instance, if for analysis, to 
 wash off adhering particles previous to its withdrawal, with a 
 little fresh solvent. The glass is then to be covered with a 
 square of window glass (free from lead), a porcelain capsule 
 or watch glass, whichever is most convenient, so that the 
 volatilized vapors condensing upon their bottoms may fall 
 back again into the vessel. 
 
 If the glass is small, it may be directly heated over the 
 lowered flame of a gas or spirit lamp. Figs. 27, 119, cautiously 
 and gradually heightened as the glass be- 
 comes heated. To modify the action of the 
 flame and diminish the danger of fracture 
 of the glass, a fine wire gauze 5, for the diffu- 
 sion of the heat, may be interposed between 
 its bottom and the flame. Fig. 255 repre- 
 sents a digestion in a beaker-glass a, over a gas 
 lamp c. For larger vessels a Sand Bath must 
 be used. 
 
 Thin flat bottomed flasks with narrow 
 necks and smooth tops. Fig. 256, made of 
 hard glass, free from lead, are sold specially 
 for this purpose; but the common sweet oil 
 or Florence flasks are much more economi- 
 cal and equally convenient for operations 
 adapted to their capacity. When it is im- 
 portant that not even a drop of substance 
 
SOLUTION. — DIGESTION UNDER PRESSURE. 
 
 303 
 
 shall be lost, as in analytic operations, the digesting flask 
 should have the form shown in Fig. 257. The body is 
 
 Fig. 256. 
 
 Fig. 257. 
 
 pear-shaped, with flat bottom, and gradually tapers towards 
 the mouth, which is lipped to facilitate the pouring of the 
 contents. 
 
 Digestion on a small scale with inflammable liquids, must 
 always be eifected by the sand bath, so as to avoid danger 
 of explosion from ignition of vaporized particles. The Sand 
 Bath may then be heated over the lamp, as at Fig. 119; and 
 in large operations by the small charcoal furnace, as at Fig. 
 87. 
 
 A digestion apparatus, of Berlin porcelain, adapted for a 
 water bath, is shown in Fig. 258. Its 
 dimensions are 7 inches in height, and 4 
 inches in diameter, the capacity being about 
 40 ounces. The projection h, is a flange 
 for its support in the bath; a, the socket 
 for a wooden handle, and c, a section of 
 the cover. These vessels, made also of 
 other sizes, are very convenient in pharma- 
 ceutical operations, for the digestion of or- 
 ganic matters, especially those of vegetable 
 origin. 
 
 Digestion under Pressure. — The solvent power of water 
 may be greatly increased by presenting it to the substance in 
 the state of vapor. This property afibrds the advantage of 
 making aqueous solutions of highly obstinate substances. The 
 appropriate apparatus is termed a digester. That which 
 Papin used for exhausting bones of their gelatin, consisted of 
 a strong hemispherical plate iron or copper pan of small size, 
 
 Fig. 258. 
 
 piMjn 
 
 ic 
 
304 
 
 SOLUTION. — D ARCET S DIGESTER. 
 
 with a self-keyed lid smoothly ground at the edges, which 
 becomes steam-tight by turning it around under clamps or 
 ears at the side. Being thus tightly adjusted, after having 
 received its charge, all steam is confined, save that which 
 esqapes by the safety valve placed at the top for the preven- 
 tion of explosion. The lever attached to the valve allows the 
 regulation of pressure according to the amount of weight 
 applied. 
 
 The efficacy of digesters is owing to the boiling point of 
 fluids being increased by pressure. When the above vessel is 
 heated, the steam generated and filling its upper and vacant 
 portion, exerts a pressure upon the surface of the liquid be- 
 neath, and by thus retarding further ebullition, causes, to a 
 certain extent, an accumulation of heat therein. 
 
 In large operations, D'Arcet's apparatus (see Encyclopedia 
 of Chemistry, article Gelatin) is much used. It is shown in 
 Figs. 259 and 260. Our description refers to the extraction 
 of gelatin from bones by water in a state of tense vaporiza- 
 tion. 
 
 Fig. 260. 
 
 Fig. 259 is a vertical section of the apparatus. A is an 
 hermetically closed cast-iron cylinder, into which the steam 
 
SOLUTION. — d'ARCET'S DIGESTER. 305 
 
 is conducted ; a the main steam-pipe ; h a vertical pipe con- 
 veying the steam into the cylinder K\ c c branch-pipes leading 
 the steam to the bottom of the cylinder; d a stopcock upon 
 the pipe 5, for regulating the entrance of the steam into the 
 interior of the cylinder. (The tubes and the cylinder should 
 be wrapped around with woolens, so as to retain their heat 
 and prevent their cooling.) e is the stopcock for the discharge 
 of the gelatinous solution ; / the cover of the cylinder, which 
 is fastened to the cylinder, so as to prevent the escape of any 
 of its contents ; g a tubulure in the cover for the reception of 
 a thermometer; A a tub to receive the solution as it is formed; 
 i a gutter for conveying into another vessel the grease which 
 is run off in the commencement of the operation; K another 
 gutter, moving on a pivot, which receives the liquid as it runs 
 from the cock g, and empties it into the tub A, or into the 
 trench i; I a tube for feeding the interior of the cylinder with 
 fresh water; m a movable adjustment attached to the pipe I 
 for regulating the quantity of water and preventing a too 
 great elevation of temperature in the interior of the appa- 
 ratus. 
 
 Fig. 260, elevation of the interior basket, made of wire- 
 cloth. This basket, or cage, receives the cleansed and crushed 
 bones, and is enclosed in the cylinder A; a is the handle with 
 which, by means of a pulley, it is lifted or lowered, to be 
 emptied or charged. Four or more of these machines make 
 a series, and the boiler which feeds them with steam should 
 carry a pressure of 4 lbs. to the inch. [Encyc. of Ohem.) 
 
 When volatile or costly liquids are used as solvents, it is 
 necessary both on the score of economy and of the efficacy of 
 the process to use certain precautions. In making pharma- 
 ceutical preparations, of which alcohol or ether is the men- 
 struum, they have an important bearing. For example, either 
 of these liquids volatilizes by a high heat, and unless the 
 vaporized particles are by a suitable arrangement condensed 
 and returned to renew action upon the substance, the latter 
 will be evaporated to dryness long before sufficient time has 
 elapsed for the completion of its solution. For this purpose 
 an ordinary cooling worm may be attached, as shown in Fig. 
 261. The vapors escaping from the digesting vessel «, are 
 condensed partly in the inclined tube ?, and partly in the 
 worm c, and fall back again into the flask as soon as they 
 become liquefied by the water surrounding the worm. This 
 
306 
 
 SOLUTION. — MOHR'S DIGESTER. 
 
 arrangement allows a prolonged contact of solids witli volatile 
 liquids, without loss or alteration of the latter — a very import- 
 ant consideration, as time is an influential adjunct in diges- 
 tion. 
 
 Fig. 261. 
 
 Fig. 262. 
 
 a 
 
 4 
 
 ! T 
 
 Mohr improves upon the above apparatus, by substituting 
 another, exhibited in Fig. 262. It consists of a tin plate 
 cylinder A, tubulated at its bottom. Through this tubulure 
 
SOLUTION. — BOILING ;— IN TUBES. 307 
 
 passes a glass tube 1 1, adjusted by perforated corks to the 
 tubulures of both cylinder and digesting vessel M. The va- 
 porized matter, ascending from the heating vessel M, is cooled 
 by the water in the cylinder, and which surrounds the tube t t. 
 The long barreled, tin plate funnel T, receives the amount of 
 water freshly added, and conveys it to the bottom to displace 
 that which has become heated, and which by its less density 
 rises to make its escape through the outlet A. 
 
 Solution by Boiling.— This mode is resorted to when a 
 substance can only be exhausted of its soluble portion at the 
 boiling point of the solvent. The exact point of temperature 
 at which a liquid boils, depends partly upon the amount and 
 fluctuations of pressure, and the nature and construction of 
 the vessel. When the pressure of supernatant vapor is re- 
 moved by uncovering the vessel, ebullition is facilitated and 
 takes place at lower temperatures. Indentation or roughen- 
 ing of the surface of the heating vessel, or any other means 
 by which the heating surface is increased and escape of 
 gaseous matter is promoted, lowers the boiling point of a 
 liquid. For this latter reason, platinum scraps or pieces of 
 unglazed card, or of cork, pacify turbulent ebullition and 
 render the process tranquil and uniform. 
 
 The heat applied should never exceed the degree at which 
 the solvent boils, especially in metallic vessels, otherwise ebul- 
 lition is retarded, for beyond a certain temperature a repul- 
 sion between the particles of liquid — when water is used — and 
 the metallic surfaces, prevents contact. 
 
 The kind of apparatus varies with the nature and quantity 
 of material under process. 
 
 Boiling in Tubes. — Test tubes. Fig. 263, are very conve- 
 nient implements for delicate solutions, assays and the like, 
 and, therefore, the laboratory should be supplied with a large 
 assortment, varying from three inches in length and a quarter 
 inch in diameter to six inches in length and one inch in dia- 
 meter. They should be of hard, white German glass, free from 
 lead, with perfectly round bottoms, uniformly thin, so as to 
 withstand heat. The racks, Figs. 25 and 147, serve as their 
 supports. 
 
 A test tube should never be charged with more than one- 
 third its capacity of solvent, else there may be loss by ejec- 
 tion from too sudden ebullition ; and the solid substance pre- 
 
308 
 
 SOLUTION IN TEST TUBES. 
 
 viously powdered is not to be added until the liquid is brought 
 to boiling, and then only in small portions at a time. 
 
 To guard against spirting or to ensure a uniform heating, 
 the tube must be gradually heated, not upon its bottom but 
 near to or on the side, as shown in Fig. 264. It is, as seen, 
 heated over the small lamp, Fig. 115, being held in the fin- 
 gers, which are protected from contact with the hot glass 
 
 Fig. 263. 
 
 Fig. 264. 
 
 yj 
 
 by a doubled strip of thick paper wrapped around the neck 
 of the tube for its support. The spring holder, Fig. 265, 
 
 Fig. 265. 
 
SOLUTION IN TEST TUBES. 309 
 
 consisting of a wooden handle affixed to two flat pieces of thin 
 steel indented at their ends so as to form a round catch, and 
 tightened or loosened bj a slide, is much more convenient but 
 not always at hand. 
 
 The mouth of the tube during heating, or whilst its contents 
 are being shaken, should always be held away from the ope- 
 rator, else ejected matter may endanger his person or dress. 
 
 Faraday gives the following valuable advice as to the use 
 of test tubes for making solutions with volatile liquids, and 
 under pressure. 
 
 " In consequence of the small diameter, and therefore 
 small sectional area of tubes, they are much stronger rela- 
 tively to internal pressure than larger vessels, such as flasks 
 of the same thickness. An advantage is thus gained in some 
 cases of solution or digestion in certain fluids, as alcohol, 
 ether, and even water, because it enables the experimenter to 
 subject the substances to temperatures as high as the boiling 
 points without loss of the fluid, or occasionally to tempera- 
 tures still higher, the ebullition going on as it were under 
 pressure. This is easily performed with alcohol, ether, and 
 similarly volatile fluids, in tubes of four, five, or six inches 
 in length, and of such diameter as to be readily and per- 
 fectly closed by the finger. Suppose a tube of this kind, one- 
 third filled with alcohol and held tightly between the thumb 
 and second finger of the right hand, its orifice being closed by 
 the fore-finger of the same hand. Fig. 251. The fore-finger 
 is to be relaxed, and the heat of a spirit-lamp applied until 
 the alcohol begins to boil ; the fore-finger is then to be reap- 
 plied closely, and it will be found that the flame of the lamp, 
 applied at intervals, is quite sufficient to keep the temperature 
 up to the boiling point. No alcohol can evaporate, for the 
 finger has power sufficient to retain the vapor even were its 
 force equal to two atmospheres, and the tube itself is also 
 strong enough to resist the same force. 
 
 *' This operation is very advantageous when valuable and 
 volatile solvents are in use ; it is therefore worth while to refer 
 to those points which indicate the state and temperature of 
 the fluid, and which make the practice easy. If the fluid be 
 one which, like alcohol, when at or above its boiling point is 
 at a temperature inconvenient to the hand, then, if all the 
 common air were allowed to pass out of the tube before clos- 
 ing it, the whole tube would become heated by the vapor 
 
310 BOILING IN BEAKER GLASSES AND FLASKS. 
 
 rising from the hot liquid beneath, and the fingers would be 
 injured ; but by not allowing all the air to escape, that por- 
 tion which is retained in the tube, is always forced to the top 
 by the successive formation and condensation of the vapor 
 below, and interfering with the passage of the hot vapor to 
 the part which it occupies, it preserves that portion of the 
 tube at comparatively low and very bearable temperatures. 
 The part thus retained at a low temperature, is proportionate 
 to the quantity of air confined in the tube ; this quantity is 
 usually a proper one if the tube be closed just after the alco- 
 hol has begun to boil, and before the upper part of the tube 
 has been heated. If too much air has been expelled, and 
 the tube is found to become hot above, the application of the 
 flame must be suspended a moment or two, the whole sufiered 
 to cool below the boiling point, the tube opened, the upper 
 part cooled slightly by a piece of moist paper or a cold 
 finger, and then the fore-finger is to be reapplied to close it 
 as before. 
 
 " The state of the fluid within is in part indicated by the 
 pressure of the air or vapor on the finger, the latter being 
 urged away from the tube by a force proportionate to the 
 degree of heat above the boiling point, and being drawn in- 
 wards when the heat is below that point. Generally, there- 
 fore, the finger alone will serve to ascertain whether the 
 temperature is above or below the point of ebullition; but 
 as the force required is, after operating for some time at high 
 pressures, such as to diminish the sensibility of the finger to 
 smaller pressures, it sometimes happens that on lowering the 
 temperature, the period at which it attains that of ebullition 
 in the atmosphere cannot be distinguished. This point is, 
 however, easily recognized by relieving the pressure of the 
 finger slightly ; should the quiescent fluid below then burst 
 into ebullition, it is a proof that its temperature is higher 
 than the boiling point at atmospheric pressure, but should it 
 remain quiescent until the finger is entirely removed, its tem- 
 perature will be known to be below that point." 
 
 Boiling in Beaker Glasses and Flasks. — These vessels are 
 used when large quantities of liquid are to be operated upon. 
 When the direct heat of the lamp is applied, it should be 
 diffused by the intervention of a wire gauze. The preferable 
 mode of heating is by a highly heated sand-bath. The same 
 remarks as to their material and construction, as given before 
 
 J 
 
BOILING IN CAPSULES. 
 
 311 
 
 at p. 303, are applicable in this instance. They should be 
 loosely covered during the operation, the beaker glasses with 
 squares of window glass and the mouths of the flasks with 
 watch glasses. The position of the beaker glass over the lamp 
 is shown at Fig. 255, that of flasks at Fig. 119. Round bot- 
 tomed flasks, Figs. 266, 267, are made of different sizes, espe- 
 
 Fig. 266. 
 
 Fig. 267. 
 
 Fig. 268. 
 
 cially for solutions, but Florence flasks, which have been 
 rounded on the edges of the mouth over the blow-pipe flame, 
 so as to allow of the easy entrance of a loose cork, are equally 
 convenient and less costly. They are thin and uniform 
 throughout, and bear very high temperatures without frac- 
 ture. Fig. 268 represents a flask being heated in a dish 
 sand-bath over a small furnace, for solutions requiring a higher 
 temperature than can be furnished by the gas or spirit lamp. 
 They must be well imbedded in the sand in order to produce 
 ebullition. 
 
 Boiling in Capsules. — Solution is made in open vessels 
 when the solvent liquid is not easily vaporizable or alterable 
 by exposure, or when its loss is of little consequence. The 
 most convenient implements for the purpose are porcelain 
 capsules. Figs. 269, 270. Those from the Royal, Dresden 
 
 Fig. 269. 
 
 Fig. 270. 
 
312 SOLUTION BY STEAM. 
 
 and Berlin factories are far superior to the French, or those 
 of anj other make. They are strong yet uniformly thin 
 throughout, and support very high temperatures and sudden 
 changes. Being enamelled they are protected from the action 
 of acids or corrosive liquids, and consequently are of general 
 application. They are sold of all sizes, by Kent, varying up- 
 wards from an ounce to 18 oz. in capacity. The diameter of 
 the smallest is about 2 inches, and that of the largest 15J 
 inches. The depth should be one-third of the diameter. The 
 smaller sizes come in nests of a half dozen or more. Fig. 
 269 represents one with spreading rim and lip to facilitate 
 pouring. That shown in Fig. 270 has a more hemispherical 
 shape. 
 
 Capsules are almost always heated over the open fire, the 
 spirit or gas lamp furnishing the requisite temperature. Those 
 of smaller size are shown in position upon suitable supports at 
 Fig. 118, and 2, Fig. 119 ; for the larger Luhm^'s lamp. Fig. 
 122 answers an admirable purpose. 
 
 The liquid is placed in the capsule before the ignition of 
 the wick, and when it is boiling, the substance to be acted on 
 should be gradually deposited in it in a finely divided state, 
 while constant stirring with a glass rod is kept up. After all 
 has been added, both ebullition and stirring must be con- 
 tinued until the completion of the process, taking care to 
 supply the loss of the volatilized portion by fresh additions of 
 the solvents, unless the solution is to be evaporated. 
 
 When the nature of the materials requires the intervention 
 of a medium other than sand to modify the heat, a rare oc- 
 currence when operating in capsules, the latter are heated 
 over baths, as shown at Fig. 150. Capsules or boiling pans 
 of enamelled iron ware or tinned copper are used only in very 
 large operations. 
 
 Solution by Steam. — "When a substance is to be dissolved 
 by steam heat, and the nature of the materials renders the 
 direct application of steam inadmissible, then baths. Fig. 11, 
 come very appropriately into play. 
 
 For aqueous solutions which are greatly facilitated by the 
 immediate action of steam, it is supplied through flexible lead 
 tubes leading from the generator. Fig. 10, directly into the 
 containing vessel. 
 
 For small operations in glass vessels, the copper spritz, 
 
SOLUTION BY DISPLACEMENT. 313 
 
 Fig. 186, half filled with water and heated over the gas lamp, 
 readily furnishes sufficient steam. 
 
 As boiling by steam is practiced in numerous chemical ope- 
 rations, it is proper to introduce some directions pertinent to 
 the subject. 
 
 It is very seldom that the heat required for ordinary labo- 
 ratory purposes exceeds that given by five pounds above 
 atmospheric pressure — never more than fifteen pounds — and 
 the fire under the generator and weights upon the safety 
 valve should be regulated accordingly. 
 
 If the mixture to be boiled is unalterable by the action of 
 condensed steam, the conduit pipe may lead directly into it, 
 and to the bottom. 
 
 As the liquid appears to boil before it actually does, the 
 only sure indication of temperature is to be obtained by a 
 thermometer. Fig. 84. 
 
 This method, however, causes a great loss of heat and in- 
 commodes the operator, by filling the apartment with clouds 
 of vapor. A loose cover will partially remove these objections. 
 In boiling in this way, care must be taken that the fire does 
 not get low, lest a condensation of the vapor occupying the 
 upper part of the boiler causes a partial vacuum, and the con- 
 sequent withdrawal of part of the liquid from the vat into the 
 boiler. The conduit connected with the feeder should always 
 have a stop-cock near the coupling, which is to be shut off 
 upon the completion of the operation. If the boiler should 
 then happen to be surcharged with steam, it must be blown 
 off through the valve, this being readily accomplished by 
 gradually unloading the lever. 
 
 A far better plan of boiling by steam is to conduct it 
 through a coil of pipe placed at the bottom of the vat, and 
 having an exhausting pipe leading into the neighboring flue. 
 This mode allows a uniform temperature at any degree from 
 that of the atmosphere to 212^ F., — suitable stop-cocks being 
 attached for that purpose to regulate the supply of steam ac- 
 cordingly. 
 
 In cold weather and especially when the feeder or conduit 
 are of any length, it will be economical to wrap them with 
 woolen listings or straw, as means of preventing conden- 
 sation. 
 
 Solution by Displacement. — Displacement, termed also 
 lixiviation, when applied to the solution of saline substances, 
 21 
 
314 
 
 SOLUTION BY DISPLACEMENT. 
 
 is an economical process for the extraction of the soluble por- 
 tions of woods, leaves, flowers, barks, precipitates, and, indeed, 
 of all matters to which suitable apparatus can be adapted for 
 the infiltration of a sufficiency of liquid through them. For 
 delicate operations and those conducted upon a scale of mo- 
 derate extent, glass vessels may be employed. One of the 
 usual form is shown in Fig. 271. It is made of hard glass, 
 free from lead, the upper part, or A, being the displacer, 
 and the lower part, B, an ordinary flask, the recipient of the 
 
 Fig. 271. 
 
 saturated solution. The mouth of the bottle and that portion 
 of the displacer which rests in it should be ground so as to 
 make a close joint. The stopple is for closing the upper ves- 
 sel when necessary. Dobereiner's improvement upon the above, 
 but operating upon the same principle, is shown in Fig. 272. 
 To prevent the passage of the material through the barrel of 
 the displacer, it must be loosely closed with a plug of raw 
 cotton as at /, and then adjusted by means of a perforated 
 cork g, with the vertical tubulure of the globular receiver a. 
 The whole apparatus as adjusted is retained in an upright 
 position by a support, the receiver resting upon a braided 
 straw ring. It is now ready to receive its charge. The 
 substance in coarse powder and moistened, occupies the part 
 of the vessel e, and the solvent is subsequently added as at d. 
 A partial vacuum being made in the receiver by the evapora- 
 
SOLUTION BY DISPLACEMENT. 315 
 
 tion of a few drops of alcohol added through the lateral stop- 
 pered tubulure c, the liquid percolates through the solid mass 
 by the force of atmospheric pressure, and ultimately reaches 
 the receiver saturated with the soluble matter of the mate- 
 rial e. 
 
 In order to express clearly the rationale of this process, we 
 will suppose that vegetable matter, a dye-wood for example, 
 in coarse powder, is to undergo exhaustion by this method. 
 It occupies the part e, as before said, and to facilitate the per- 
 colation, has been previously moistened with a portion of the 
 solvent. Liquid is added, as shown at d, and soon soaks into 
 the mass beneath ; another portion of solvent is then poured 
 in as before, and takes the same course, displacing the portion 
 before used without mixing with it. These strata of solvent 
 are pressed downwards by successive additions of liquid, and 
 become more and more charged with soluble matter, as they 
 approach the bottom of the mass, until at last they run out 
 into the recipient highly charged and in the present instance, 
 highly colored — the first runnings being more nearly saturated 
 than those which follow. When by consecutive additions of 
 solvent the material has been exhausted, the liquid in its 
 transit through the mass is unacted upon, and reaches the 
 receiver as tasteless and uncolored as when first poured in. 
 This indicates the completion of the process. 
 
 The neck of a retort with its smaller end adjusted to a wide 
 mouth bottle by means of a perforated cork, makes an excel- 
 lent displacing apparatus. 
 
 When the solvent is volatile, in order to prevent loss by 
 evaporation, the apparatus is modified, as shown in Fig. 273. 
 The displacer is adapted to the centre tubulure 
 of a two necked Wolffe bottle. Now as atmo- Fig. 273. 
 spheric pressure is an important element of this 
 process, it will not do to shut it ofi" by closing 
 the top of the displacer without making some 
 other arrangement, and, therefore, a communi- 
 cation between the upper and lower vessel is 
 established by means of a bent tube adjusted 
 in the lateral tubulure of each. In this man- 
 ner the vessel is completely closed, and vapor- 
 ization prevented while the pressure produced 
 is distributed throughout the vessel, and thus 
 rendered uniform. In using the glass displacement appa- 
 
 I 
 
316 SOLUTION BY DISPLACEMENT. 
 
 ratus first described, this principle must be recollected ; 
 where a vacuum is not artificially created in the receiver, the 
 ground glass edges of it and the displacer should either be 
 permanently separated or occasionally disjointed. 
 
 The stop-cock near the bottom of the receiver allows the 
 withdrawal of the solution as fast as it accumulates, without 
 the necessity of disarranging the apparatus. In experiments 
 upon large quantities of material, and in pharmaceutical ope- 
 rations generally, the displacers employed are made of tinned 
 copper or tin plate. Those of porcelain which are now in the 
 market, are much more serviceable, because they are readily 
 cleansed and resist the action of corrosive liquids. Of what- 
 ever material they are made, they should be cylindrical and 
 funnel-shaped at the base, and the height should be at least 
 four times the diameter, as is shown in Fig. 274. At a 
 there is a flange in the interior as a support for the cul- 
 lendered diaphragm a h. These diaphragms are removable, 
 and for convenience in handling have a knob in the centre. 
 The lower diaphragm is always to be covered with a circle 
 of coarse muslin for the reception of the material and to pre- 
 vent the passage of particles as well as obstruction of the 
 holes. The other diaphragm, fitting loosely to the cylinder, 
 rests upon the top of the powder and serves for the better 
 distribution of the solvent and for the prevention of the escape 
 of dusty particles which sometimes occurs if the powder is put 
 in dry. The stop-cock c in the barrel or exit pipe is useful 
 for regulating the discharge of the liquid. 
 
 The tripod D is the support, and allows the withdrawal of 
 the receiver P, when it is full and when it is to be replaced 
 by another, without the necessity of disturbing the displacer. 
 
 Another very convenient form of displacer is that in which 
 ether, alcohol and any other volatile solvent may be kept in 
 constant action without exposure to air or loss by evaporation. 
 By its use a great saving of time and labor and solvent is 
 gained. The arrangement is exhibited at Fig. 275. It con- 
 sists of a glass cylinder B, the funnel of which should reach 
 to the centre of a glass balloon A, beneath the two vessels, 
 being attached by means of a perforated cork. The lateral 
 tube c, d opens communication between the lower and upper 
 apartments. As the whole forms a perfectly tight connection, 
 the safety tube E becomes necessary for the regulation of the 
 dilatation and contraction of the vapors. 
 
SOLUTION BY DISPLACEMENT. 
 
 317 
 
 When it is desired to exhaust a vegetable matter with 
 alcohol or ether, and at one and the same operation to con- 
 
 Fig. 274. 
 
 Fig. 275. 
 
 C 'HllfiD i 
 
 centrate the charged solvent, plug the barrel of B, with raw 
 cotton, previously moistened with the liquid to be used, add 
 the powdered material, cover it with a cullendered disc, pour 
 on the liquid in quantity sufficient to give a filtered solution 
 of half the capacity of the balloon, and then connect the 
 apparatus. The balloon is now to be placed half its depth in 
 the water bath H, and the apparatus sustained in a perpen- 
 dicular position by means of a clamp support. The water 
 bath is to be closed with a loose cover, and heated as may be 
 
318 SOLUTION IN CLOSE VESSELS. 
 
 required by the small spirit lamp i. The ether or alcohol 
 which has infiltrated into the balloon thus carried to, and 
 maintained at ebullition, passes oflf as vapor into the lateral 
 tube, there partially condenses and falls upon the material in 
 the cylinder to infiltrate through again. The excess of vapor 
 and of expanded air escapes through the safety tube ; but a 
 part of the vapor is arrested and condenses in the three bulbs, 
 the first of which immediately empties its liquefied contents 
 into the cylinder to renew its action upon the powder. 
 
 The concentration of the filtered solution is thus continually 
 going on in the balloon, the concurrent distillation returning 
 the evaporated particles to the substances to be exhausted, 
 through the lateral tilbe c, d. 
 
 When water is the liquid to be employed, the water bath 
 must be replaced by a saline or sand bath, and the spirit lamp 
 by a furnace. 
 
 For the solution of diflScultly soluble substances, this mode 
 presents many advantages not possessed by other processes, 
 and amongst others it yields a clear solution and supersedes 
 the necessity of filtration, which is required for most solu- 
 tions made by infusion, decoction and boiling. It is par- 
 ticularly applicable to the purpose of procuring concentrated 
 solutions for evaporation to extracts, as well as for making 
 tinctures, &c. 
 
 The solvent may be acid, alkaline, spirituous, ethereal or 
 aqueous in its nature, the principle of its action being the 
 same in all cases. When the liquid is corrosive, however, the 
 vessel should not be metallic, but of glass or porcelain, and 
 should be plugged with asbestos instead of cotton. It is im- 
 material whether the solvent be applied cold or warm, save 
 when the process is resorted to for the separation of sub- 
 stances soluble in cold from those which are only soluble in 
 hot liquids. Except in such cases heat may be applied, as it 
 increases the power of the solvent, and a convenient means 
 of doing so is to encompass the apparatus with a metallic 
 jacket, to be supplied with steam from the generator. Fig. 10. 
 
 There are certain conditions necessary to the success of 
 this operation. The material must be in powder of medium 
 division; neither too fine nor too coarse, for in the first 
 case it clogs the cloth and holes of the diaphragm, and if 
 heavy and compact, retards the percolation of the liquids: — 
 on the other hand, when too gross, the transit of the solvent is 
 
cadet's mode of solution. 319 
 
 so rapid that the material is but partially acted upon. When 
 alcohol or ether is used, the powder may be a little finer than 
 for less volatile solvents; and all powders liable to set, or to 
 become so compact as to prevent the passage of liquid, must 
 previously be mixed with well washed coarse white sand. This 
 addition remedies the defect and ensures the easy passage of 
 the solvent. 
 
 The material, as before recommended, should be moistened 
 with half its weight of the solvent, and left to soak for an 
 hour or more before being placed in the percolator. After 
 having been transferred, it is covered with the diaphragm, 
 and sufficient liquid is poured upon it to cover entirely its 
 surface. As soon as this first portion infiltrates through the 
 mass, another portion is added, for it is only by keeping the 
 surface covered with solvent that a uniform penetration of all 
 portions of the mass can be efiected. If the liquid passes 
 through very rapidly the mass is too loose, and must therefore 
 be compressed by pressing upon the diaphragm cover. Or in 
 order to prolong their contact, the stop-cock c may be nearly 
 closed, so as to allow the exit of only a thin stream. 
 
 When alcohol or other valuable volatile liquid is used, the 
 residual portions may be either extracted by pressure of the 
 mass p, or by displacement with water; and subsequently, by 
 distillation of the resulting mixture. The general practice, 
 however, in the Laboratory is to reserve the last running for 
 the first application to fresh material. 
 
 Cadet's Mode op Solution — This plan is well adapted to 
 those powders which do not admit of being easily infiltrated. 
 It consists in macerating or infusing the pulverized material 
 with double its weight of cold or hot solvent, and after some 
 time subjecting it to strong pressure. This treatment is to 
 be repeated until the substance ceases to yield soluble matter, 
 and the resulting liquids are then mixed together and filtered. 
 Cadet's mode is used largely for dissolving the tannin from 
 galls with ether. 
 
 A convenient press for this purpose is shown at Figs. 276 
 and 277. All powders which have undergone the process of 
 solution in large quantity should be subjected to its action, as 
 a good deal of retained solution may thus be obtained, and 
 consequently saved. 
 
 It is formed of two strong upright stanchions, and two 
 proportionably strong cross pieces, firmly jointed in the side 
 
320 
 
 CADET S MODE OF SOLUTION. 
 
 beams. The upper cross piece carries a box through which 
 works an ordinary press screw, in the usual manner. Upon 
 the lower cross piece, is placed a wooden trough, A (Fig. 277) 
 
 Fig. 276. 
 
 Fig. 277. 
 
 n I n 
 
 ■ 
 
 A 
 
 at least two inches deep, and to the front of which is adapted 
 a gutter B for the conveyance of the liquid, which assembles 
 in the trough, to a vessel E placed at and beneath its mouth. 
 Upon and within the trough is placed a wrought iron plate 
 cylinder. This cylinder is formed of two semi-cylinders 
 joined together. Throughout its height, it is divided off 
 alternately into equal parts by zones or belts. The zones a a 
 are more than an inch broad; — the partition, 5, &c., four or five 
 inches in width. The top as well as the lower zone is narrow. 
 All the wider divisions are cullendered throughout their cir- 
 cumference with innumerable small holes, through which the 
 liquid is to flow when pressure is applied. All the narrow 
 zones are secured by a strong wrought iron ring, formed 
 of two pieces working on a hinge adjusted at the back. Upon 
 the front is a movable broach D, which bolts them together, 
 and makes the cylinder compact, so that it can resist the 
 pressure applied. When the marc is exhausted, by draining 
 out the broach D, the circumference of the cylinder is loosened 
 or extended, so that its contents can be removed without 
 difficulty. The marc is placed in this cylinder and pressed 
 out by the power of the screw, until no more fluid will exude, 
 even with the force of a man to the lever. The liquid runs 
 into the gutter B and through a sieve, which should be pro- 
 perly placed for the purpose, into the vessel E, and may thence 
 be drawn off after it has settled, into suitable vessels. The 
 
SOLUTION UNDER PRESSURE OF STEAM. 
 
 321 
 
 residual exhausted powder is, as said above, easily emptied 
 out by loosening and removing the pin D. 
 
 Solution under Pressure of Steam. — Figs. 278 and 279 
 exhibit Duvoir's bucking apparatus, which as modified in the 
 
 Fig. 278. 
 
 Fig. 279. 
 
 drawings, is applicable to the exhaustion of organic matter. 
 B B are the wooden vats lined with lead which receive the 
 material to be displaced ; a G the cullendered diaphragms for 
 its support; and c c their movable covers counterpoised so as 
 to admit of ready depression or elevation at will. These false 
 bottoms are also movable, so as to afford facility in cleansing 
 the vat, and they should, when in use, be covered with crash 
 cloths to prevent obstruction of the holes. The tubes d d, 
 communicating with the steam generator. Fig. 10, traverse 
 the centre of the vats, and are surmounted by metallic discs, 
 E E, for the reverberation of the vapor rushing against them. 
 The directions for the management of the apparatus are 
 nearly the same as for displacement generally. When the vat 
 has received its charge, the cover is to be lowered and fastened 
 down by clamps, and steam let on by opening the stop-cock 
 of the feeder. As the steam generates, it passes over through 
 the pipe D, reaches the disc E, and is projected uniformly over 
 the whole surface of the material. The elastic force of the 
 vapor accumulating in the upper portion of the vat exerts a 
 pressure upon that portion which has condensed and forces it 
 downwards through the mass. In its passage it becomes 
 
322. EVAPORATION. 
 
 charged with soluble matter and reaches the lower part of the 
 vat K beneath the diaphragm, whence it is drawn off through 
 the cock L, R. 
 
 As a safeguard against accidents there should be a safety- 
 valve upon the cover of the vat as well as upon the generator. 
 
 This arrangement would be particularly economical in the 
 arts, for extracting 'dye woods and other vegetable substances. 
 
 CHAPTER XXI. 
 
 EVAPORATION. 
 
 When any liquid is heated for the purpose of expelling 
 vaporizable matter, and the process is conducted solely with 
 a view to saving its fixed portion, the operation is termed 
 evaporation. It thus far differs from distillation, which has 
 for its object the preservation of the volatilized portion, in 
 most cases, regardless of the solid. By its aid we can decrease 
 the volume of, or concentrate solutions for crystallization and 
 chemical reaction, expel valueless volatile ingredients from 
 those which are more fixed, obtain dissolved matter in a dry 
 state, and prepare extracts and other pharmaceutical pro- 
 ducts. 
 
 Liquids evaporate more or less at all temperatures, those 
 having the lowest boiling point yielding the most readily ; but 
 there are certain conditions which greatly promote this tend- 
 ency. It must be remembered, therefore: — 
 
 1. That evaporation is more rapid in dry atmospheres, and 
 that consequently the transit of a constant stream of air over 
 the surface of the heated liquid effects a continual removal 
 of each stratum as it becomes saturated with vapor. 
 
 2. That evaporation is confined to the surface, and conse- 
 quently that the breadth of the evaporating vessel must be 
 extended at the expense of its depth. 
 
 3. That heat greatly facilitates evaporation by lessening 
 the cohesive force of the particles of a liquid, and consequently 
 that the evaporating vessel should present a broad surface to 
 be heated. 
 
EVAPORATING VESSELS. — SPONTANEOUS EVAPORATION. 323 
 
 4. That a diminution of the atmospheric pressure also 
 facilitates evaporation, for the more perfect the vacuum the 
 lower the boiling point of a liquid. 
 
 Evaporating Vessels. — For analytic purposes, capsules of 
 Berlin porcelain are by far the best implements. The cap- 
 sules should be very thin, with steep sides, spout for pour- 
 ing, nearly flat bottomed, and glazed throughout. Watch 
 glasses answer for small experiments, but require to be very 
 cautiously heated, as they are readily fractured. 
 
 Beaker glasses are also used for evaporating solutions which 
 would lose by being transferred. Broad mouthed glass flasks 
 are of but limited application for evaporating, and are only 
 employed for slow processes with valuable liquids, which are 
 liable to alteration by too much exposure when ebullition is 
 necessary. 
 
 For the larger operations of the ^^s- 280. 
 
 Chemist or Pharmaceutist, vessels 
 (Fig. 280) of copper, tin, enamelled 
 iron, tinned copper, and for some 
 purposes very large porcelain cap- 
 sules are more suitable. 
 
 Retorts are used when the vapor- 
 ized particles are of sufiicient value 
 to be condensed, as in the process of distillation. 
 
 Spontaneous Evaporation. — Those liquids which are very 
 volatile, or which become altered by heat, are evaporated by 
 mere exposure to the atmosphere at its ordinary temperature. 
 To this end they are poured into broad shallow vessels, and 
 placed aside until the dissipation of all vaporizable matters, 
 or until crystallization; this mode of evaporation being also 
 employed for procuring large crystals, which are better de- 
 fined than those obtained by rapid evaporation. 
 
 The more dry and hot the atmosphere the more rapid is 
 the evaporation. In order to maintain a continued contact 
 of the surface of the liquid with strata of fresh air, the vessel 
 containing it should be placed in a draught, so that those 
 portions of air which become saturated with vapor may be 
 displaced. 
 
 When the air might act injuriously, and a vacuum is un- 
 necessary, a substance may be evaporated in another atmo- 
 sphere, for instance, of hydrogen or carbonic acid. For this 
 purpose it is only necessary to adjust the disengagement leg 
 
324 EVAPORATION IN VACUO. 
 
 of the apparatus (Fig. 219) to the tubulure of a retort, so that 
 its end may reach nearly to the level of the liquid in the 
 latter. The generated hydrogen passes into the retort heated 
 to the required temperature, and promotes the discharge of 
 the vapors into a recipient attached to the beak of the retort, 
 and fitted with a small tube in its other tubulure for the dis- 
 engagement of uncondensed portions. 
 
 For the evaporation of solutions of sulpho-bases, of sulpho- 
 salts, and of all substances readily oxidizable by exposure, 
 this process is better applicable than that with the air-pump, 
 which is apt to be attacked when the eliminated vapors are 
 corrosive. 
 
 This process is much used in crystallization, for concen- 
 trating alterable solutions, and drying precipitates. 
 
 Evaporation in Vacuo. — We have already referred to the 
 happy influence of diminished atmospheric pressure in facili- 
 tating evaporation, and shall now speak of the means by 
 which it is accomplished, and the particular instances in which 
 it is employed. 
 
 This mode is resorted to for hastening the evaporation of 
 all liquids, but more especially of those which are alterable 
 by exposure. 
 
 In small experiments we use a capped bell glass (pp. 337, 338) 
 as the confining space. Under this bell glass is placed the 
 broad shallow capsule, with its liquid contents, supported upon 
 a wire tripod resting in a leaden tray containing sulphuric 
 acid, dried chloride of calcium, fused potassa, or some other 
 absorbent material. The bottom or bed of the bell may be a 
 ground glass plate, and to seal the joints hermetically the rim 
 of the bell should be greased. Connection being made by 
 means of a suitable pipe and the stop-cocks between the bell 
 and the syringe, communication is opened and the vessel 
 exhausted of air. The pressure being thus removed, evapora- 
 tion proceeds rapidly, and until the absorbent matter becomes 
 saturated with vaporized particles, or the bell filled, there is 
 no impediment. The latter can be partially removed by 
 working the pump at frequent intervals. 
 
 When an air-pump is used the procedure is the same, but 
 in either case the vacuum must be produced gradually, other- 
 wise the sudden ebullition of the liquid may cause ejection of 
 its particles. The better way is to cease pumping as soon as 
 the barometer attached to the machine indicates from two to 
 
EVAPORATION BY HEAT IN OPEN AIR. 325 
 
 two and a half inches pressure, and to resume the process of 
 exhausting again at intervals of fifteen or thirty minutes. 
 
 Other modes of evaporating in vacuo, as practiced in the 
 arts, are fully described in lire's Dictionary of Arts, and 
 under Sugar ^ in the '^ Encyclopedia of Chemistry J" Howard's 
 and Barry's vacuum pans are the most effective implements. 
 The latter is applicable in Pharmacy for making extracts upon 
 an extensive scale. It consists of a hemispherical pan with 
 a tightly fitting cover, in the centre of which is a bent tube 
 leading into a copper spheroid of four times the capacity of 
 the pan. This tube is fitted with a stop-cock, which allows a 
 communication, at will, between the spheroid and pan. An- 
 other cock at the opposite end is made so as to couple with 
 the conduit of the steam generator* 
 
 The liquid to be evaporated is introduced into the basin, 
 which is then to be hermetically closed and placed in a water 
 bath. The cock connecting with the spheroid being closed, 
 a current of steam is let on, and continued until the entire 
 expulsion of air from the pan ; access of steam is then stopped 
 by closing the cocks, and a sheet of cold water applied to the 
 exterior. A condensation of vapor ensues, and a partial 
 vacuum is produced. Communication being then opened with 
 the caldron, uniform expansion of the air ensues; and as the 
 capacity of the spheroid is four times greater than that of the 
 pan, the latter contains only one-fifth of its original amount 
 of air. Several repetitions of this manipulation produce a 
 sufficient vacuum. The water bath is then heated until the 
 liquid within the pan commences to boil, as may be seen 
 through the small window left for the purpose, and the cool- 
 ing of the spheroid continued. When the liquid has reached 
 the required thickness, the operation may be discontinued. 
 In this way ebullition proceeds at 100° F. under a pressure 
 sixteen times less than that of air. With an air syringe 
 attached for removing the vapor as fast as formed, the power 
 of the apparatus would be greatly increased. 
 
 Evaporation hy Heat in Open Air. — Having already noted 
 the effects of heat in facilitating evaporation, we proceed to 
 make known its modes of application. As the boiling points 
 of solutions differ, so accordingly their evaporations are 
 eff^ected at varying temperatures. For example, aqueous or 
 other solutions of unalterable matter may be evaporated over 
 the fire; others which are destructible by heat require the 
 
326 
 
 intervention of Baths. In whatever mode the operation is 
 performed the general principles are the same, and whether 
 the vessel be a porcelain capsule or metallic pan, the greater 
 its width in proportion to its depth the more rapid is the 
 evaporation. Constant agitation with a stirrer is also pro- 
 motive of the process. 
 
 Evaporation over Water and Saline Baths. — When solu- 
 tions are alterable at a temperature above 212° F., the cap- 
 sule or containing vessel is heated over the water-bath. Fig. 
 150. 
 
 If it requires a higher heat, but one not exceeding 300° F., 
 then the water must be replaced by a saline-bath, p. 184. 
 
 Evaporation hy Steam. — This mode has many advantages 
 over all others, not among the least of which is that with the 
 aid of the generator, Fig. 10, any number of vessels may be 
 heated simultaneously, and in any part of the laboratory, it 
 being only necessary to have conduits of sufficient length to 
 convey the steam to them. Moreover, convenient stop-cocks 
 allow a regulation of the heat, and consequently all danger 
 of injury to the evaporating solution is avoided. By increas- 
 ing the pressure of the steam the temperature of the solution 
 is also elevated. 
 
 Steam is applied through metallic coils placed at the bot- 
 tom of the containing vessels, and having an exit pipe leading 
 into the neighboring flue, or else by means of metallic casings. 
 This latter mode, by far the best, is given in detail at pp. 42 
 and 181. 
 
 Evaporation over Sand-baths. — This mode is much used in 
 analyses and for careful evaporations, requiring temperatures 
 greater than 212°, and yet not so high as those given by the 
 naked fire. The position and arrangement of the vessels are 
 as directed under the head of Sand-baths. 
 
 Evaporation hy Heated Air. — This mode is admirably 
 adapted for the inspissation of the natural juices of plants or 
 for preparing dry extracts. It is also applicable to the com- 
 pletion of evaporations which have been carried as far as is 
 safe over the naked fire. Porcelain plates or panes of win- 
 dow glass are the vessels used, and a stove or apartment for 
 their reception heated from 95 to 110°, with a free draught 
 passing through are the means of obtaining the required tem- 
 perature. The juice evaporates either to thin scales or else 
 to a spongy mass, as in the case of tannin extracted by ether, 
 
EVAPORATION BY HEATED AIR ; — OVER THE FIRE. 32T 
 
 and as soon as it reaches dryness, the plates or panes are to 
 be withdrawn, and their contents removed with a spatula. 
 
 Evaporation over the Naked Fire. — The tendency of many 
 substances to decomposition over fire, especially organic, even 
 when in solution, renders this mode inapplicable save when 
 the solvent and substance dissolved are both inalterable below 
 the boiling point of the former. It is resorted to for expe- 
 diting evaporations, but otherwise is far more inconvenient 
 than steam, because of its affording less facility for the regu- 
 lation of the heat and requiring greater attention. The con- 
 taining vessel should be placed over a furnace of small dimen- 
 sions, and its contents continually stirred with a porcelain 
 spatula — this precaution preventing decomposition or carboni- 
 zation, provided the temperature is not allowed to exceed the 
 boiling point of the solvent. 
 
 In analysis and other processes, the heating implement is 
 generally the gas or spirit lamp. Figs. 26, 27. The cap- 
 sule filled to about two-thirds its depth with liquid, being 
 placed in position, the flame is applied gradually and main- 
 tained just low enough to prevent ebullition ; and in order to 
 facilitate the process, and at the same time to allay turbulence, 
 it should be frequently stirred with a glass rod. The same 
 directions apply when the operation is performed in a beaker 
 glass, as is done in some analytic experiments ; and Eig. 255 
 shows its position over the lamp. 
 
 A cover of white paper prevents access of dust without 
 retarding the process, but care must be taken that the con- 
 tents of the vessel be not ejected against it, thus causing a 
 loss. 
 
 In evaporating to dryness, towards the end of the process 
 the flame must be so managed as to impart a uniform heat 
 to all parts of the thickened solution. The interposition of 
 a very thin plate of sheet iron between the flame of the lamp 
 and the bottom of the heating vessel is an additional means 
 of preventing spirting. These precautions and constant stir- 
 ring will prevent the loss of particles which is liable to occur 
 upon the disengagement of the last portions of liquid. If the 
 liquid drops a powder during the operation, the vessel must be 
 inclined, and in order to prevent spirting, heated above the 
 deposit. 
 
 A platinum spatula is a very useful implement for detach- 
 ing any efflorescent matter which may "travel up" the sides 
 of the vessel. 
 
328 CRYSTALLIZATION ; — BY FUSION ; — BY SUBLIMATION. 
 
 CHAPTER XXII. 
 
 CRYSTALLIZATION. 
 
 When a body in the act of passing from a liquid or gaseous 
 to a solid state arranges itself in symmetrical forms, the pro- 
 cess is termed crystallization, and the parts of the body so 
 aggregated are called crystals. 
 
 By this process we can separate crystallizable from amor- 
 phous substances dissolved in the same menstrua; purify 
 crystals from foreign and coloring matters, and in qualitative 
 examinations, be enabled to determine the composition of 
 bodies by a reference to the characteristics of figure. 
 
 The modes of crystallization are by fusion, sublimation, 
 SOLUTION and chemical reaction. 
 
 Crystallization hy Fusion. — Sulphur, lead, bismuth, tin, 
 antimony, silver, numerous alloys, anhydrous salts and other 
 fusible substances which are unalterable by heat are crystal- 
 lizable by FUSION. 
 
 To this end they are melted at the lowest possible tempe- 
 rature, and allowed to cool very gradually. As soon as a 
 crust forms upon the top, which may be readily seen by the 
 surface becoming furrowed, it must be pierced with a rod and 
 the still fluid portion decanted with sufficient dexterity to 
 prevent it from cooling during the process, and at the same 
 time from injuring the crystals coating the interior of the 
 vessel. 
 
 The liquid matter should be placed so as to be free from all 
 vibration. The greater the mass of the material and the 
 more slowly it is cooled the more voluminous and better de- 
 fined will be the crystallization. 
 
 Crystallization by Sublimation. — Volatile solids, as iodine, 
 camphor, several metallic chlorides and mercurial compounds, 
 arsenic, benzoic acid, iodide of lead, &c., when heated as 
 directed in sublimation, yield vapors which, in cooling, 
 take the form of crystals. 
 
 Crystallization from Solution. — When it is desired to ob- 
 
CRYSTALLIZATION FROM SOLUTION. 329 
 
 tain a substance in crystals, it must first be liquefied or made 
 into a SOLUTION with an appropriate liquid. If, after mak- 
 ing the solution, there be any insoluble residue it must be 
 separated by filtration ; and subsequently, if the solution 
 is capable of decolorization by such means, it should be boiled 
 with a small portion of clean bone or ivory black, and again 
 filtered. As it is the almost universal law that heat increases 
 the solvent power of bodies, the solution should generally be 
 made and clarified at the boiling point, so that the excess 
 of matter taken up at the high temperature may separate on 
 cooling in the form of crystals. 
 
 So long as a solution is dilute it yields no crystals ; — these 
 latter are only formed when the containing liquid is super- 
 saturated, or, in other words, holds more than it can retain; 
 and consequently in diminishing the quantity of the liquid by 
 evaporation, we increase the density of that which re- 
 mains, and hence, upon cooling, it deposits that excess of 
 the dissolved substance which it only held by virtue of its 
 high temperature. 
 
 Some substances are so easily soluble, and to such an un- 
 limited extent, that their solutions form crystals immediately 
 upon cooling ; others again are taken up with such difficulty, 
 even at high heats, unless in large bulks of liquid, that although 
 exposed to prolonged ebullition they require to be evaporated 
 in order to separate what has been dissolved. As the mode 
 of evaporating has an important influence upon the form and 
 size of crystals, we give some hints as to the proper manner 
 of performing it. 
 
 If large and well defined crystals are required, the solu- 
 tion should be subjected to spontaneous evaporation, for the 
 more slow and uniform the concentration, the more regular 
 and gradual will be the superposition of material required to 
 make distinct and large crystals. A slight addition of solu- 
 tion of gelatin will, in some instances, it is said, give the 
 crystals the form of plates, as in the case of boracic acid. 
 
 The solution should be removed from the fire as soon as 
 drops, withdrawn by a glass rod and deposited upon a watch 
 glass or clean spatula, give small crystals upon cooling. If, 
 however, a very dense crystallization is required, the concen- 
 tration may be continued until a pellicle forms upon the top, 
 but then the solidified masses are confused and less brilliant. 
 These essays indicate that the liquid is evaporated to a point 
 22 
 
830 CRYSTALLIZATION : — GRANULATION. 
 
 at which it cannot retain all of its soluble matter. The ves- 
 sels are then placed aside to cool gradually and uniformly, 
 that the excess may crystallize out of the liquid. The tem- 
 perature should be regular, for slight variations may alter the 
 form of the crystals. 
 
 Bodies equally soluble in cold and hot water, as well as 
 those which are deliquescent, require a prolonged evaporation 
 as they only crystallize from very dense solutions. 
 
 When the liquid is to be converted wliolly into solid, then 
 the process is termed granulation^ and is practiced by con- 
 centrating it to a syrupy consistence, removing the vessel 
 from the fire and stirring it constantly until the mass has 
 cooled into granules. This mode is adapted for purifying 
 pearl-ash and converting it into sal tartar, and also for grain- 
 ing brown sugars. 
 
 If the liquid, evaporated as above directed, becomes colored 
 or murky during the process from partial decomposition, it 
 may be treated with bone black, and again filtered into a 
 capsule, or other vessel, previously warmed by a rinsing with 
 hot water, so as to prevent confused crystallization from sud- 
 den contact with its cold surfaces. The blue stone-ware cap- 
 sules, which are made of suitable forms by Mr. Perrine, of 
 Baltimore, are far better than porcelain capsules or glass 
 beakers, as they are not only more durable, but by the rough- 
 ness of their interior surfaces far more promotive of crystal- 
 lization. Stone basins for this purpose, called crystallizers, 
 are made of all sizes, in depth greater than in breadth, and 
 with a lip to facilitate the separation of the residual liquid 
 from the crystals. This residual liquid, called the mother 
 water, is usually returned to the evaporating vessel to be 
 further concentrated for the production of a new crop of 
 crystals, particularly if the liquid has been homogeneous. 
 
 The first crop of crystals is generally purer than subse- 
 quent ones, but may still not be sufficiently free from foreign 
 salts and other matters, and, therefore, require to be dis- 
 solved anew and recrystallized as at first. The pure crystals 
 are drained of their mother water by inclining the crystal- 
 lizer over the evaporating vessel long enough to allow all of 
 the fluid to run off at the spout. The crystals are then re- 
 moved with a spatula and transferred to a drying frame. In 
 the first crystallization the mass of impure crystals are drained 
 upon a filter, and if necessary to free them from syrupy or 
 
PURIFICATION OF CRYSTALS. 331 
 
 dirty liquid, enclosed in a cloth and pressed (Fig. 276). 
 Sometimes, especially when the crystals are not very soluble, 
 they may be drenched while upon the filter with cold water, 
 which carries away much soluble impurity. This solution, if 
 valuable, may be mixed with the mother waters, and the whole 
 after being transferred to the evaporating vessel be concen- 
 trated and again crystallized. The crop thus obtained is 
 very impure, and requires to be drained on a cloth and 
 pressed, and subjected to as many treatments with bone black, 
 and renewed crystallizations, as are required to remove all 
 color. It must be remembered, however, that bone black is 
 only used when the coloring substance is organic, and when 
 the characteristic color of the crystals is light, for it has no 
 blanching action upon either organic or unorganized bodies 
 which are naturally tinted. 
 
 In recrystallizations only as much water as is necessary to 
 efifect solution should be used, so that the mother waters may 
 be as small in quantity as possible. The last mother waters 
 being incapable of yielding any more crystals, may, in some 
 processes, be reserved for other purposes ; as, for instance, 
 making new compounds. Thus, for example, the mother 
 waters of iodide of potassium may be used to precipitate 
 iodide of mercury from the bichloride of that metal, or of 
 lead from the nitrate of lead, and those of chloride of barium, 
 to obtain carbonate of baryta upon the addition of carbonate 
 of soda. 
 
 Sometimes, however, crystallization is resorted to for the 
 separation of one substance mixed with others which are 
 variably soluble in the same liquid, and which do not crystal- 
 lize together, but separate from the solvent when at different 
 densities ; — in this case the mother waters may contain one 
 or more of the other components of the original substance, 
 and hence are not useful for forming new compounds by 
 Precipitation. After the separation of each to the fullest 
 extent by crystallization, at different temperature, the residue 
 of liquor, unless it be of great value, may be thrown away. 
 
 As before said, gradual evaporation at a uniform tempera- 
 ture, and a perfect repose of the concentrated solution, give 
 the most perfect crystals. Some solutions, however, crystal- 
 lize less readily than others, and remain even days and weeks 
 without exhibiting any sign of such tendency. In such cases, 
 it is advisable to agitate the mass slightly or to stir it gently 
 
332 CRYSTALLIZATION BY CHEMICAL REACTION. 
 
 with a glass rod. This manipulation arouses, as it were, the 
 molecules from their inertia, and frequently determines speedy 
 crystallization. The resulting crystals are generally, how- 
 ever, confused and diminutive. 
 
 To obtain large crystals from a solution which is slow in 
 depositing them, it is sometimes proper to add nuclei to the 
 cold solution, these consisting of well formed large crystals 
 of the same substance. As the solution increases its density 
 by spontaneous evaporation, the nuclei assume a large size; 
 but in order that their enlargement may be uniform through- 
 out, they must be turned daily, so that the accumulation of 
 matter may take place on all their surfaces. 
 
 This mode, as practiced in the arts, is somewhat modified. 
 The deposition surfaces are increased by inserting in the solu- 
 tion strings as nuclei. When one solution is thus exhausted 
 of its soluble matter, the strings with their surrounding crys- 
 tals are transferred to as many fresh vats consecutively as 
 are required to give the crystals the proper size. In this 
 manner, blue vitriol, prussiate of potash, tartar emetic, and 
 rock candy are crystallized. 
 
 When the twine loops are replaced by slender twigs or 
 branches of wood, and the crystals are deposited in fine 
 flakes from bulky solutions, the process is termed arborization. 
 
 Examples of arborization, where, however, crystallization is 
 accompanied by chemical or voltaic action, are furnished by 
 the various metallic trees, which are clusters of metallic flakes 
 or crystals precipitated upon the surface of a dissimilar metal 
 suspended in their solution. 
 
 Qrystallization hy Chemical Reaction. — The newly formed 
 compounds, resulting from the chemical reaction, frequently 
 assume the crystalline shape. Thus, for example, antimony 
 roasted in contact with air forms crystals of antimonious acid ; 
 chlorine acting upon phosphorus produces crystals of perchlo- 
 ride of phosphorus. So, likewise, crystals of bicarbonate of 
 potassa are produced when carbonic acid is passed through a 
 concentrated solution of carbonate of potassa. 
 
 Silver displaced from its solutions by zinc forms a crystal- 
 line deposit. Sulphate of lime precipitated by alcohol from 
 its aqueous solution also falls in crystals. Morphia, also, and 
 other crystalline alkaloids, may in like manner be precipitated 
 by decomposing their solutions with ammonia. 
 
DESICCATION ; — OF SOLIDS. 333 
 
 CHAPTER XXIII. 
 
 DESICCATION. 
 
 The desiccation of a substance consists in the expulsion of 
 its " moisture." The term moisture is used only in reference 
 to that variable amount of water, and sometimes, though 
 rarely, of other liquids which it may have absorbed, or other- 
 wise retained in a state of mechanical union. The combined 
 water or that of crystallization, of which many bodies are in 
 part constituted, exists in an entirely different form, and is 
 not usually to be expelled when the drying is preliminary to 
 analysis. When, however, it is desired to dehydrate a body 
 entirely, this latter water of combination is also to be dis- 
 sipated. 
 
 The means of desiccation are various, and differ with the 
 nature of the substance to be dried, its quantity, and altera- 
 bility by heat and exposure. 
 
 Desiccation op Solids. — Undecomposable salts and any 
 substances unalterable by air or heat, may be dried by fusion. 
 If the amount of moisture is to be determined, the crucible 
 and its contents should be weighed before and after the ope- 
 ration, the loss expressing the weight of water expelled. 
 Those bodies, however, which will not bear the heat necessary 
 for fusion, can be desiccated by evaporation to dryness in a 
 capsule — care being taken to renew surfaces by constant stir- 
 ring. 
 
 Those saline matters which readily yield all their water by 
 exposure may be reduced to powder or effloresced by subject- 
 ing them in thin layers to a draught of dry air which, if 
 necessary, may be moderately heated. For this purpose as 
 well as for that of drying crystals which do not effloresce, it 
 is necessary in manufacturing laboratories to have a special 
 apartment. This room should be smoothly plastered within, 
 and need not be of large size. As a means of ventilation its 
 opposite sides are pierced with small holes, which, to prevent 
 the admission of dirt, are covered with wire gauze. The inte- 
 
334 
 
 DESICCATION IN AIR CHAMBERS. 
 
 rior is fitted with trellis shelves for the support of the wooden 
 frames, stretched over with white muslin, and upon which the 
 substance rests between or upon, as may be required, folds 
 of bibulous white paper. The heat is communicated by sheet 
 iron flues proceeding from a stove placed outside of the en- 
 closure, or by means of steam pipes fed by the generator, 
 Fig. 10. The temperatures should range from 75 to 110° F. 
 
 This apartment is also useful for pharmaceutical purposes, 
 for drying plants, roots, seeds, woods, &c. They may either 
 be suspended or spread in thin layers upon frames, and re- 
 peatedly turned for the purpose of exposing fresh surfaces. 
 
 The air chamber, p. 35, may, to a limited extent, be made 
 to replace this apartment, and in an experimental laboratory 
 it is, together with the means mentioned in this chapter, 
 sufficient for all purposes. 
 
 As the salts effloresced as above still retain a little water, 
 they require to be repeatedly pressed between the folds of 
 white paper until dampness ceases to be imparted to them. 
 Sometimes a previous trituration is necessary to facilitate the 
 process. 
 
 Filters containing precipitates after careful removal from 
 the funnel and compression between the folds of bibulous 
 paper, may be further dried in the same manner. Those, 
 however, which contain the results of analytic experiments 
 require more careful manipulation. For their treatment a 
 copper-plate oven is often used. It consists (Fig. 281) of a 
 brass soldered copper box 7x9 inches, enveloped by a steam- 
 Fig. 281. 
 
 tight jacket, in the door of which are vent holes for change 
 of air. The water, or the olive oil which is used if the sub- 
 stance requires a heat higher than 212° for its desiccation, 
 is poured through the centre aperture at the top, but must 
 not more than half fill the jacket. The lateral opening is for 
 
DESICCATION BY MEANS OF BATHS. 
 
 335 
 
 the reception of a thermometer, which is adjusted by means 
 of a perforated cork, for facilitating the regulation of the 
 temperatures. 
 
 The watch glasses, plates, or capsules in which the sub- 
 stances to be dried are placed, rest upon the perforated 
 shelves in the interior. 
 
 The thermometer will indicate with precision the tempe- 
 rature of the bath, and care must be taken that the latter be 
 not allowed to exceed the degree above which the body to be 
 dried decomposes. 
 
 When for any reason it is deemed inadvisable to remove 
 the filter from the funnel, they may both be dried together 
 in a hot air oven. Fig. 282. The apparatus shown in the cut 
 is a copper double or single cased cylinder, with a 
 movable cover, to facilitate the introduction of the 
 substances to be dried. In its centre is a circular 
 aperture for the reception of the thermometer by 
 which the heat is regulated. A perforated dia- 
 phragm serves as a support for the funnels, watch- 
 glasses, capsules or other vessels, and in order to 
 promote the evaporation, a current of air through 
 the interior is excited by means of the circular aper- 
 tures in its upper and lower circumference. 
 
 These baths are all heated over small furnaces 
 or preferably over the gas lamp, a uniform heat 
 being maintained by careful management of the 
 flame. 
 
 " Eig. 283 represents an arrangement for drying substances 
 
 Fig. 282. 
 
 Fig. 283. 
 
 in a current of dry air produced by the efflux of water. For 
 
336 DESICCATION OF EASILY ALTERABLE SUBSTANCES. 
 
 this purpose a known weight of the substance is introduced 
 into the small bent glass tube (Fig. 284), 
 Fig. 284. which has also been weighed ; the body of 
 
 this tube is plunged into a copper water bath 
 h, charged with a saturated solution of com- 
 mon salt ; it is kept in its place by a cover 
 furnished with two apertures for the arms of 
 the drying tube ; the wider arm is united by 
 means of bent tubes and a caoutchouc con- 
 nector with the U-shaped tube, and containing fragments of 
 chloride of calcium, and the narrow end is connected with a 
 bent tube, which passes through the cork of the bottle A 
 nearly down to its bottom. This cork must fit the bottle 
 perfectly air-tight, and all the joints and connections of the 
 whole apparatus must be perfect. The bottle A is filled with 
 water, which on turning the stop-cock s flows out in a small 
 stream, its place being supplied by the air drawn through c, 
 and which becomes dried during its passage through the 
 chloride of calcium, tube h. The bath is charged with water, 
 a saturated solution of common salt, or of chloride of calcium, 
 according to the degree of heat required, and it is kept boil- 
 ing by means of a spirit or gas lamp placed underneath." 
 
 Desiccation of easily alterable Substances. — It has already 
 been said that the power of absorbing and retaining moisture 
 varies in different bodies. This property renders the use of 
 those which have it in the greatest degree available for the 
 drying of others which are deficient in it. The substances 
 subjected to this mode of drying are mostly organic bodies 
 and those readily alterable by heat or exposure, but which 
 yield their moisture much below 212° F. 
 
 This method of desiccation can be conducted very well in 
 an apparatus consisting of a large bell glass, fitting accurately 
 upon a ground glass plate or bed. Within is a shallow saucer 
 5, containing dry chloride of calcium, strong sulphuric acid, or 
 other highly absorbent material, and over it a perforated glass 
 support a, upon which rest the capsules, crucibles, beaker, 
 watch glass, or other containing vessels. Fig. 285 exhibits 
 the whole arrangement. The rim of the bell, as also that 
 part of the plate which it touches, are to be greased, in order 
 to make the joint hermetical. The material thus exposed to 
 dry air continues to lose moisture until all has been expelled, 
 
DESICCATION OF EASILY ALTERABLE SUBSTANCES. 
 
 337 
 
 or until the absorbent matter has become saturated ; in such 
 case the latter must be replaced with a fresh quantity. 
 
 Fig. 285. 
 
 By substituting the bed of an air-pump for the glass disk 
 as a support for the other parts of the apparatus, otherwise 
 arranged exactly as above described and shown in the figure, 
 and increasing the evaporation by exhausting the air, desic- 
 cation proceeds much more rapidly and efi'ectually. A partial 
 vacuum being thus produced the drying substance liberates 
 its aqueous vapor freely, new portions being given off as soon 
 as those which preceded them are condensed by the absorbent 
 in the saucer, which is usually in these cases strong sulphuric 
 acid, that agent absorbing watery vapors perhaps to a greater 
 extent than any other. The process is thus continued until 
 complete desiccation of the substance and saturation of the 
 absorbent material take place, the latter being replaced by 
 a fresh quantity when the former has not been completely 
 dried. 
 
 If the eliminated vapors are corrosive it is advisable to 
 modify the arrangement, so that they may be neutralized as 
 fast as generated, otherwise the metallic surfaces of the air- 
 pump will be injured. A suitable apparatus is shown in Fig. 
 286. It is an inverted bell glass, fitted at its neck with a 
 stop-cock, by which it connects with a tube containing pumice 
 stone impregnated with acid or alkali, according to the nature 
 of the vapors to be absorbed. The substance to be dried and 
 the absorbent or hygroscopic body are arranged within the 
 bell in the usual manner. The latter is then greased at its 
 
3B8 
 
 DESICCATION IN VACUO. 
 
 edges, hermetically covered with a ground glass plate, and 
 exhausted of air by a syringe coupled with the further end of 
 the drying or chlorcalcium tube e. 
 
 Fig. 286. 
 
 By* having a bed of ground glass instead of metal, and 
 detached from the pump or syringe, and made to commu- 
 nicate with it by flexible lead pipe and gallows screws only 
 when exhaustion is required, an apparatus is made, which, as 
 represented in Fig. 285, becomes available for all the pur- 
 poses of evaporation and desiccation. 
 
 Another mode of drying alterable and fixed substances in 
 vacuo is shown by the arrangement. Fig. 287, which efiects 
 a repeated change of air. It consists of a copper cylinder 
 
 Fig. 287. 
 
 box, soldered with brass, having two apertures in its top, — 
 one, g^ for the reception of a thermometer by which to regulate 
 the temperature, and the other for a glass tube g, the recipient 
 of the substance to be dried. This tube is connected by 
 means of a smaller glass tube 2, tightly adjusted in perforated 
 
DESICCATION OP LIQUIDS. 339 
 
 corks "with the chloride of calcium tube d, and thence also 
 with the exhausting syringe h. Heat being applied to the 
 bath* by means of a small furnace or gas lamp a partial vacuum 
 is then produced by several strokes of the syringe piston. In 
 a few moments air is to be admitted through the cocks c and a, 
 and this exhaustion and airing is to be repeated at occasional 
 intervals, the air in its transit being deprived of all moisture 
 by the chloride of calcium. When it is desired to replace 
 atmospheric air by carbonic acid, hydrogen, or other gas, it 
 may be introduced by connecting the gasometer containing 
 the required gas by suitable couplings with the same appa- 
 ratus. 
 
 Desiccation of Liquids. — Desiccation properly means the 
 freeing of a body, capable of existing in a dry state, from 
 accidental moisture. But for the sake of uniformity of de- 
 scription we have applied the term also to the separation, from 
 fluids, of water, which is the ordinary source of moisture. This 
 is usually done by the agitation with the liquid of some ab- 
 sorbent material, which either unites with the water, forming 
 a stratum of different density capable of being separated by 
 filtration or decantation; or else combines with it so firmly 
 that the fluid which is usually more volatile can be separated 
 by distillation. 
 
 Thus alcohol and other spirits are rectified by distillation 
 over carbonate of potassa, chloride of calcium, or free lime, it 
 being only necessary to stop the process as soon as the liquid 
 comes over slowly, which indicates that all the pure spirit has 
 passed. Agitation of ether with any of the same absorbents 
 produces similar results. 
 
 For analytic purposes, and in minute experiments, liquids 
 which are less volatile than water may be freed from it by 
 exposure in open vessels under the receiver of an air-pump as 
 described for solids in the preceding paragraphs. 
 
 Desiccaton of Gases. — Nearly all gases in the course of 
 elimination become involved with more or less moisture, from 
 which it is frequently desirable to separate them previous to 
 their application to chemical reaction. For this purpose they 
 are passed over some highly absorbent material, such as dried 
 chloride of calcium, quicklime, or sulphuric acid. 
 
 * This bath is that known as Rammehberg's Air Bath, which is used alone for 
 drying substances inalterable at tolerably high temperatures. 
 
340 DESICCATION OF GASES. 
 
 The simplest arrangement for the purpose is given at Fig. 
 148, which exhibits a straight tube d d, containing the dried 
 chloride of calcium, adapted at one end by means of a per- 
 forated cork with the gas generator A, and at the other, in 
 like manner, with a disengagement tube e e. The gas in its 
 transit through the chlorcalcium tube is relieved of its moisture. 
 This tube varies in size from half to one inch diameter, and 
 eight to twelve inches length, according to the quantity of 
 gas to be desiccated. The chloride of calcium can be replaced 
 by quicklime, potassa, or pumice stone impregnated with 
 sulphuric acid, as the nature of the gas may require; but in 
 either case the solid material should be in small lumps. The 
 water formed during the process collects in this tube. 
 
 Liebig uses the drying tube of such a form as is shown at 
 Fig. 288. It differs from the above in having a bulb, and in 
 
 Fig. 288. 
 
 being drawn out at one end to a fine tube, thus leaving but 
 one aperture to be corked. Lumps of absorbent matter are 
 placed in the bulb, and coarse powder of the same substance 
 in the long part, each end of which is very loosely plugged 
 with raw cotton to prevent the exit of particles. 
 
 For small operations the bent form. Fig. 289, is most 
 convenient, as it is easily adjusted to the 
 Fig. 289. mouth of the bottle without the necessity of 
 
 rp<^"~ ^ 1 ^^ multiplying joints. The bulbs in these two 
 g latter tubes serve also as wells for the recep- 
 
 tion of the condensed vapor. 
 Dumas's vertical drying tube, designed for the desiccation 
 of large quantities of very moist gas, is so constructed that 
 the condensed vapor instead of remaining in contact with the 
 pumice, and thus impairing its absorbent power, will be de- 
 posited in the lower part. The tube leading from the gene- 
 rating vessel is adapted by means of a perforated cork to a 
 lateral tubulure at the base. The disengagement tube is 
 similarly adapted to the top. 
 
 The selection of the drying, or hygroscopic material must, 
 as before said, be made with a regard to the nature of the gas ; 
 thus, for example, quicklime should never for obvious reasons 
 
DESICCATION OF GASES. 
 
 341 
 
 be used for desiccating chlorine, or other gases which combine 
 with it chemically ; for the drying of nearly all such gases an 
 acid body may be employed, and pumice stone in lumps of 
 about the size of half of a pea, impregnated with sulphuric 
 acid, is very serviceable, as it presents a large extent of sur- 
 face. For this purpose, however, the pumice must be freed 
 from all the chlorides which it contains, otherwise the sul- 
 phuric acid will disengage muriatic acid possibly to the great 
 detriment of the gas, which is undergoing drying. The best 
 way is to pulverize and moisten it with sulphuric acid, and 
 subject it to calcination in a crucible. When, after constant 
 stirring it ceases to disengage acid vapors, the operation is 
 finished. 
 
 Anhydrous phosphoric acid is also occasionally employed 
 as a drier, but only in very nice experiments. It is mixed 
 with clean asbestos, which occupies the same position in the 
 tube as any of the other absorbents. 
 
 As a means of perfect desiccation it is often required to 
 combine the absorbent powers of two different materials in 
 one apparatus, and for this purpose the U form of drying 
 tube is most convenient. It presents a large extent of sur- 
 face in a limited space. There is, however, a disadvantage 
 in arranging and adjusting its parts firmly together, and also 
 in the necessity of occasionally renewing the hygroscopic 
 substance more frequently than in the straight tubes. 
 
 Fig. 290 exhibits a proper arrangement of the U tubes for 
 the desiccation of gas. By this mode the gas may be introduced 
 
 Fig. 290. 
 
 directly from the generating vessel, as shown at Fig. 148, or 
 from a gas bag or gasometer as seen in the drawing above. 
 The latter communicates with a pair of U shaped glass tubes, 
 
342 PRECIPITATION. 
 
 which are connected together by means of bent tubes, per- 
 forated corks and flexible India rubber joints. In one of 
 their legs is placed dried chloride of calcium, and in the op- 
 posite one asbestos or lumps of pumice stone impregnated 
 with sulphuric acid. The reservoir on the top of the gas- 
 ometer being filled with water, and its pressure applied by 
 opening the cocks, a stream of gas is gradually expelled and 
 in its transit through the tubes is freed from its moisture by 
 the absorbents. 
 
 CHAPTER XXIV. 
 
 PRECIPITATION. 
 
 This process is employed for the immediate separation of 
 a body in the solid state, both from mechanico-chemical and 
 simple solutions. The reagent, which is used to produce the 
 action, is termed the precipitant and the resulting deposit the 
 precipitate. 
 
 Bodies in some instances may be precipitated unaltered, but 
 in most cases, being the result of chemical reaction, are mo- 
 dified or entirely changed in their nature. Thus, for example, 
 sulphate of lime may be precipitated from its simple aqueous 
 solution by alcohol and the basic phosphate of magnesia and 
 ammonia by aqua ammonise, they being insoluble in that liquid, 
 the addition of which is also without chemical action upon 
 the original solution. For like reasons the resins are precipi- 
 tated from alcoholic solutions by water; and gutta-percha 
 from solution in chloroform by ether. If, however, carbo- 
 nate of soda or other soluble carbonate is substituted for the 
 alcohol then the original combination is broken up by the 
 action of double elective affinity, an exchange of bases taking 
 place, and insoluble carbonate of lime precipitating instead 
 of the unaltered sulphate as in the instance with alcohol. So 
 also, an analogous result would ensue by virtue of simple 
 elective affinity if soda is used instead of the carbonate, the 
 lime then falling in a free state, having been deprived of its 
 sulphuric acid by the caustic alkali. 
 
 i 
 
VESSELS FOR PRECIPITATION. 848 
 
 The consistence of the precipitate and its form and color 
 vary with the nature of the solutions, and the rapidity with 
 which it is produced. These distinctive features serve as 
 characteristics by which, in analysis, the presence of certain 
 bodies is determined. 
 
 The precipitate is differently termed according to its ap- 
 pearance. It is flocculent, when it falls in small flakes or 
 flocculae, like those produced by ammonia in solutions of per- 
 oxide of iron; pulverulent when in fine powder and compact 
 like the sulphates of lead or of baryta; granular if deposited 
 in minute irregular molecules; crystalline, when it subsides 
 in minute crystals, as the bitartrate of potassa, sulphates of 
 silver and of lime ; curdy when cheesy, like that thrown down 
 by chloride of sodium from nitrate of silver, and gelatinous 
 when of the consistence of jelly, as alumina freshly separated 
 from alum by carbonate of potassa. 
 
 Precipitating Vessels. — The most convenient vessels, used 
 in analysis, are the beaker glasses, Fig. 254, or 
 wide mouth flasks, Fig. 266, the latter being used ^^s- ^^'• 
 only when the process is to be practiced upon the 
 boiling liquid. When solutions are precipitated, 
 especially for the purpose of collecting the pre- 
 cipitates, the form of the vessel may be that of 
 the one in the drawing. Fig. 291, which ensures 
 the subsidence of all the deposit and prevents 
 particles from adhering to the sides. They may 
 be of glass or blue stoneware according to the 
 amount of liquid under process. 
 
 In chemical investigations, the test tubes. Fig. 263, are the 
 most convenient implements. They permit the operator to 
 use minute quantities, and they are readily heated and 
 shaken. As a precipitate is in some instances not percep- 
 tible for some hours, especially in dilute solutions, sufiicient 
 time should be allowed to elapse before deciding upon the 
 reaction of a preciptant upon a solution. 
 
 Directions for Precipitating. — Both the material and re- 
 agent must be in solution and separately clarified by filtra- 
 tion before being commingled, otherwise the suspended mat- 
 ters will subside with the precipitate. As heat generally 
 promotes the reaction and the subsidence of the precipitate, the 
 solution should, in such cases, be warmed, or even made hot, 
 and the reagent cautiously added during continual stirring 
 
344 DIRECTIONS FOR PRECIPITATING. 
 
 ^ith a glass rod so that all parts of the liquid may be brought 
 in contact. The vessel is then set aside upon a sand bath or 
 in a warm place until the deposition of the precipitate has left 
 the supernatant liquor clear. A few more drops of precipitant 
 are then added, and, if all the matter has been thrown down, 
 they will produce neither precipitate nor cloudiness, but if a 
 portion still remains in solution, still more of the reagent 
 must be added. The addition of the reagent or precipitant 
 must be gradual, for besides the waste of material and incon- 
 venience of washing it out, an excess in certain instances re- 
 dissolves the precipitate. As soon as a drop or two of reagent 
 ceases to give cloudiness or precipitate in its descent through 
 the supernatant liquid of the settled solution, its addition must 
 be discontinued and the vessel placed aside, and, after suffi- 
 cient repose, subjected to decantation or filtration to 
 separate the solid from the liquid portion, the latter of which 
 is also usually to be reserved in analysis or when it is of value, 
 as it may contain other newly formed compounds dissolved 
 in the menstruum employed. 
 
 When the precipitate about to be formed is somewhat soluble 
 in the liquid of the original solution, the amount of that 
 liquid must be diminished by evaporation, and the precipita- 
 tion effected in a concentrated solution; for example, in the 
 reaction of solutions of strontia with sulphuric acid or solu- 
 ble sulphates. 
 
 Metals may be precipitated from their solution by other 
 metals having a greater affinity for oxygen than is possessed 
 by those in combination; — thus copper may be precipitated 
 from its sulphate by iron, lead from the nitrate by zinc, and 
 silver, arsenic and mercury from their solutions by copper. 
 A slight acidulation of the liquid facilitates the process, and 
 the metallic strips used as reagents must be clean and bright. 
 
 Metals are also precipitated by voltaic action, a familiar 
 instance of which is the art of plating by galvanism. 
 
DECANTATION. — FILTRATION. 345 
 
 CHAPTER XXV. 
 
 DECANTATION. — FILTRATION. 
 
 Precipitates which are substances deposited by any means 
 from liquids in which they have been dissolved or chemically 
 combined, may be separated either by decantation or filtra- 
 tion. The first mode is applicable to those solids which are 
 of much greater density than the menstrua containing them, 
 and which readily and rapidly subside forming heavy com- 
 pact deposits. In delicate experiments, however, and in all 
 cases where the liquid is turbid and deposits its suspended 
 matter reluctantly, the latter plan is most appropriate. 
 
 Besides being a process subsequent to precipitation for 
 the separation of the clear supernatant liquor from the sub- 
 sident matter, decantation is also useful in levigation. 
 For WASHING precipitates which require a large amount of 
 water, or frequent renewals of the wash waters, it is much 
 more convenient than filtration. This latter mode, however, 
 must, as before said, be always adhered to in analyses and 
 when the precipitate is light and apt to be disturbed during 
 decantation. 
 
 Decantation from small vessels in nice experiments is 
 practiced by gently inclining the vessel whether it be a 
 capsule, as at Fig. 292, or a beaker glass, Fig. 293, and 
 
 Fig. 292. Fig. 293. 
 
 allowing the liquid to run down in a continuous stream 
 along a glass rod placed against its rim or edge. This ope- 
 23 
 
346 
 
 DECANTATION ; — POURINa. 
 
 Fig. 294. 
 
 ration of pouring requires a degree of dexterity which is 
 indispensable in analytic operations in order to avoid loss of 
 material. The exact position of the rod is shown in the 
 figures. When the pouring is completed the rod should be 
 tilted upwards for a moment, so as to prevent the loss of ad- 
 herent drops and immediately returned to the vessel, the edge 
 of which should be slightly greased so as to effectually pre- 
 vent any particle of liquid from passing over. These pre- 
 cautions are only necessary in the decantation and filtration 
 of liquids, during analytic processes ; so much care being un- 
 necessary in less important manipulations, as it is of little 
 consequence if the liquid does carry over a little of the pre- 
 cipitate or suffers a slight loss. If the bulk 
 of liquid is very small, it may be removed 
 with pipettes. Figs. 59, 60, p. 107; for larger 
 quantities a syphon is requisite. This im- 
 plement may be of glass or lead tubes, the 
 former being cleanly and of more general 
 application than the latter. The shapes 
 given in the drawings refer to those of either 
 material. The most simple form is that 
 shown by Fig. 294, being similar to an in- 
 verted V with its opposite branches of un- 
 equal length. The long leg may be from 
 12 to 20 inches in length, the shorter one 
 proportionably less. The clear diameter is 
 from an eighth to an half inch, according to 
 the extent of the operation. 
 
 This syphon is inserted and filled with 
 water or any other liquid which is without 
 action upon that in the vessel, the mouth of the longer leg 
 is then closed with the finger and the shorter branch intro- 
 duced, mouth downwards, into the liquid to be decanted until 
 it nearly reaches to the level of the precipitate without dis- 
 turbing it. Upon removing the finger the liquid ruif^ out in 
 a continuous stream and may be almost wholly drawn off by 
 slightly inclining the vessel. 
 
 The rationale of the operation is as follows : — When the 
 short leg of the syphon is dipped into water the liquid mounts 
 into the tube as high as the surface of that which is in the 
 containing vessel. Now the weight of the atmosphere^ bears 
 equally upon the surface of that in the vessel and in the 
 syphon, but if the elastic force of the internal air is removed 
 
DECANTATION ; — SYPHONS. 
 
 347 
 
 Fig. 295. 
 
 or diminished by suction with the mouth at the other end, or 
 by having previously filled the syphon with water, the liquid 
 runs over, and as the weight of the column of water in the 
 long leg is greater than that in the short one, the flow 
 will be continuous while the mouth of the short leg is im- 
 mersed in liquid, for no air can enter to produce an inter- 
 ruption. 
 
 If the liquid is not injurious or unpleasant to the taste, 
 the syphon may be inserted in the liquid without previous 
 filling, — suction with the mouth at the long end drawing it 
 over. 
 
 For the decantation of caustic liquids the syphon is fur- 
 nished with a lateral tube, as shown in 
 Fig. 295, which serves as a protection to 
 the mouth. Its application is similar to 
 that of the one described above (p. 346); 
 the short leg is dipped into the liquid to 
 be decanted, the lower end closed with the 
 finger, and suction practiced at the orifice 
 of the supplementary tube until the air is 
 removed and the liquid runs over and al- 
 most reaches the mouth, when the decan- 
 tation goes on continuously after the with- 
 drawal of the mouth and finger. 
 
 The annexed drawing. Fig. 296, exhi- 
 bits these syphons in operation. 
 
 A length of cotton wick doubled in 
 syphon form, and having its short end 
 
 Fig. 296. 
 
348 filtration; — through paper. 
 
 immersed in the liquid also acts as a syphon, but is much 
 slower in its operation. 
 
 The use of the syphon allows the separation of the liquid 
 without disturbance of the settled matter, but as the latter 
 still retains more or less fluid which cannot be separated in 
 this way, it may be thrown upon a filter and in large opera- 
 tions even subjected to pressure in cloths, as directed at p. 
 320. 
 
 FILTRATION. 
 
 The mode most commonly resorted to of separating solid 
 substances from liquids in which they are suspended, is that 
 of filtration^ and it is also occasionally but rarely used for 
 the purpose of disuniting liquids. The process consists in 
 passing the mixture through suitable media of sufficient 
 porosity to allow the transit of the liquid portions while they 
 intercept any solid particles. For the separation of liquids 
 the texture of the medium must be such that it is penetrable 
 by or attractive of the one, but impervious to the other, of 
 them, as it is upon this that the success of the operation 
 depends; thus, for example, moistened paper will allow the 
 passage of water, but not of oil. 
 
 Paper, brown muslin, linen, crash, woolen and canton 
 flannel, felt, raw cotton, sand, asbestos, crushed quartz, bone 
 black — each and all have their appropriate application as 
 media, and when thus used are all styled filters or strainers — 
 the first title being almost exclusively applied to those of 
 paper supported upon funnels, while the latter is limited to 
 the other textures or bodies which are either suspended upon 
 frames for pharmaceutical operations or deposited in proper 
 vessels. 
 
 This process is of equal importance in chemical and phar- 
 maceutical operations. In analysis it enables us to separate 
 precipitates or insoluble residue from liquids, and to obtain 
 each free from particles of the other — an indispensable 
 condition where both are to be further acted upon for obtain- 
 ing accurate results : while in ordinary operations we can by 
 its aid free liquids from dirt and other foreign matters, and 
 render them transparent. 
 
 Filtration through Paper. — Paper is more generally 
 
filtration; — through paper. 340 
 
 used, particularly in delicate experiments, than any other 
 medium. It is advisable always to use that which is white^ 
 for it contains no coloring matter to deteriorate the liquid 
 which traverses it. Moreover, it should he free from saline 
 impurities which are soluble in acid or alkaline liquids, other- 
 wise the accuracy of analytic results may be materially inter- 
 fered with. 
 
 The laboratory should be provided with two qualities of 
 paper, one of fine quality for nice investigations and another 
 somewhat inferior for the less important processes. There 
 are certain conditions requisite in both kinds. They should be 
 unsized, yet strong, and while sufficiently porous to allow the 
 ready passage of the liquid, compact enough in texture to 
 retain all the solid portions. 
 
 '^German filtering paper" answers very well for all gene- 
 ral purposes, but for analytic investigations that known as 
 " Swedish" filtering paper is the best. Being made expressly 
 for the purpose and of purified rags, it is free from lime, copper 
 and salts, which have to be removed from other paper by 
 treatment with pure hydrochloric acid and repeated rinsings 
 in distilled water before it becomes fit for such uses. 
 
 The Swedish paper is whiter and thinner than the German, 
 and is made with great care ; and leaves by incineration only 
 ^J^th of its weight of ashes, an important point in analyses 
 where the amount and nature of the ashes left by the paper 
 require to be considered. 
 
 The paper drawer should be kept always supplied with a 
 stock of filters of all the required sizes. The use of the 
 Swedish paper should be limited to the filtration of finely 
 divided precipitates. The greater porosity of the German 
 renders it more applicable for rapid filtration, and as it is 
 much less expensive, all large filters should be formed of it. 
 
 The filters must be circular, and cut by tin patterns, 
 which should consist of difierent sizes of 2 J, 3, 3 j, 4J, 6, 7 J, 
 9, and 12 inches in diameter. This mode of cutting different 
 sized filters from one sheet of paper, is economical and saves 
 the waste which would be occasioned by indiscriminate use of 
 the paper, while many serious delays may be prevented by 
 having a supply always at hand. 
 
 The ashes of the piece of Swedish filter of each size, must 
 be determined by incinerating one and accurately weighing 
 the residue, and engraving its weight upon the tin pattern by 
 which it is formed. Thus, in analyses, we can know by refer- 
 
350 
 
 FILTRATION : — FUNNELS. 
 
 ence to the figures the amount of fixed matter (ash) in each 
 particular size. Kent, of New York, keeps the different 
 sizes for sale, put up in neat boxes containing one hundred. 
 
 The supports for these circular filters, folded into conical 
 form as hereafter directed, are funnels which vary in mate- 
 rial and form according to the nature of the operation. They 
 may be of glass, porcelain, or stone-ware. The first, free 
 from lead, are of almost general application for analytic pur- 
 poses, and the latter two for pharmaceutical. Funnels of 
 metal are seldom required in the laboratory, a very few in- 
 stances only demanding the use of lead or platinum. 
 
 The glass funnels should be made with straight sides, in- 
 clining to an angle of about 60°. This 
 shape. Fig. 297, is indispensable for the 
 smaller funnels used in analyses, as it 
 forms in its interior a true cone, which 
 allows the admission of a larger amount 
 of liquid in a small space. The pint fun- 
 nels, and those of still larger size, may 
 have an inclination of ten degrees less, 
 but if their section has not nearly the 
 form of an equilateral triangle, the filters 
 fit badly and work imperfectly. A slight 
 rounding off of the angle at a, where the 
 apex of the conical filter rests, greatly 
 promotes the filtration. 
 
 The laboratory must be supplied with a series of funnels,* 
 
 Fig. 297. 
 
 * In addition to the above there are two other kinds of funnels used 
 for separating liquids, which have no chemical affinity and differ in density. 
 
 Fig. 298. 
 
 Fig. 299. 
 
FILTRATION : — FUNNELS. 351 
 
 ranging as follows, IJ, 1}, 2, 2 J, 3 J, 4 J, 5 J, and 6 J inches 
 in the greatest diameter of the body b. Of the smaller sizes, 
 it will be well to have duplicates or triplicates as they are the 
 most frequently employed. The stock is not complete with- 
 out one or two miniature funnels of thin glass for filtering 
 into test tubes in qualitative investigations ; and one or two 
 of convenient size with long barrels c, for charging retorts 
 and deep vessels. 
 
 Sometimes the glass funnels are ground at the rim, so as to 
 be tightly closed by a glass disc, but being expensive they are 
 only used in rare instances. 
 
 Funnels are sometimes made of porcelain with longitudinal 
 ribs in the interior of the body, as shown at 
 Fig. 300, for preventing the adhesion of the Fig. 300, 
 
 filter to the sides in the filtration of large 
 quantities of bulky precipitates. The object 
 is, however, not effected by these means, for 
 the paper sinks into the channels and ad- 
 heres to the surface, and still retards the 
 passage of the liquid. A better way will be 
 to use the plaited filters. Fig. 308. 
 
 Funnels are also made of porcelain and 
 more seldom of stone-ware. They are less 
 fragile and more applicable to the filtration of very acid and 
 corrosive liquids, and some other few purposes, than those of 
 glass; but those of porcelain are not less costly. The form 
 of those usually found in the market are shown in the an- 
 nexed drawing. They are all glazed throughout and made 
 very strong, and those used for transferring liquids from one 
 vessel to another have the convenience of handles. In this 
 respect they are preferable to the glass vessels, which by fre- 
 quent rough handling are more apt to be broken. Fig. 301 
 exhibits the form used for acids, and Fig. 302 the same fun- 
 nel ribbed in its interior. Figs. 303 and 304 present the 
 less convenient globular shape. Those shown at Figs. 305 
 
 They are fitted with stop-cocks in their barrels, as shown in Figs. 298 and 299 ; 
 and one is stoppered also at tlie top to prevent evaporation when volatile liquids 
 are under process. 
 
 The mixed liquids of oil and water, or ether and water, for instance, are 
 poured in the mouth, and after sufficient repose for the deposition of the heavier 
 of the two, it can be drawn off by opening the stop-cock which may be imme- 
 diately closed as soon as all has passed. The lighter liquid which is thus re- 
 tained may afterwards be transferred in the same way to another bottle. 
 
352 FILTERS FOLDED AND INTRODUCED INTO FUNNELS. 
 
 Fig. 301. Fig. 302. Fig. 303. 
 
 Fig. 304. 
 
 Fig. 305. 
 
 Fig. 306. 
 
 and 306, cullendered at the base, are the most convenient of 
 all, being very useful for draining crystals, for the filtration 
 of viscous solutions through cloth filters, and for small opera- 
 tions of lixiviation. 
 
 Filters Folded and introduced into Funnels, — Two kinds 
 of filters are generally employed, the plain. Fig. 307, and 
 the plaited, Fig. 308. The former are used in analyses and 
 
 Fig. 307. 
 
 Fig. 308. 
 
 whenever the suspended or precipitated matters of a liquid 
 are to be preserved. It is almost impossible to entirely re- 
 move the solid matter from the folds of a plaited filter, con- 
 sequently such are chiefly applicable for the filtration of 
 bulky precipitates from large quantities of liquid. This mode 
 of folding a filter prevents its close adhesion to the glass, and 
 greatly expedites the process by increasing the surface, and 
 
PLAIN AND PLAITED FILTERS. 
 
 853 
 
 by allowing a bubble of air to ascend in the fold every time 
 that a drop of liquid descends from the filter. 
 
 The plain filters are folded as follows: — 
 
 " When a filtration is to be performed, one of these circular 
 papers of the proper size is selected (Fig. 309), and then 
 doubled over one of its diameters {a h, Figs. 309 and 310), 
 and then over the radius {c e, Figs. 310 and 311) perpen- 
 dicular to the first diameter, so as to form a quadrant. One 
 
 Fig. 310. 
 
 of the folds is then opened, forming a hollow cone, as repre- 
 sented in Fig. 313, which will fit accurately in the funnel, if 
 the sides of the latter form an angle of 60°. If the angle be 
 greater or smaller, it is necessary to double the filter the 
 second time over another radius {c f, Figs. 309 and 312), not 
 
 Fig. 313. 
 
 Fig. 311. Fig. 312. 
 
 fie/ 
 
 perpendicular to the first diameter, and then open the large 
 or small fold {a ef, or b of, Fig. 312), according to the angle 
 of the funnel, and this repeated until a coincidence of the 
 filter with the inside of the funnel is effected." 
 
 Fig. 314. 
 
354 
 
 FILTRATION : — SUPPORTS FOR FUNNELS. 
 
 To form the plaited filter, take a square of paper and fold 
 it diagonally, as in Fig. 314 ; turn A upon B to obtain the 
 crease E and open it ; then double A upon E in the same 
 direction, to make the plait P, and double the plait A back 
 upon F, so as to form the crease G, and holding this plait be- 
 tween the fingers make the fold between F and D. Divide 
 the spaces between E B and B D in the same manner. 
 
 The filters, as above made, after having their folds opened, 
 as at Figs. 307 and 308, are placed in the funnels and so 
 adjusted as to fit nicely to the sides. In order to secure an 
 uninterrupted flow of the liquid, and to prevent the breaking 
 of the filter, the apex must not extend too far into the barrel 
 of the funnel. Moreover, the filter should be a little smaller 
 than the funnel, for if it reaches to the rim, evaporation of 
 the liquid ensues from the edges, and thus, in analysis, may 
 be a source of error. 
 
 The proper position of the plain filter in the funnel is shown 
 at Fig. 316, and that of a plaited one at Fig. 315. 
 
 In using large funnels the filter may be supported by a 
 plug of raw cotton placed in the barrel at its junction with 
 the body. 
 
 Fig. 315. 
 
 Fig. 316. 
 
 The usual support for funnels is the convenient portable 
 stand. Fig. 316. It consists of a wooden upright b, screwed 
 into a wooden bed plate. The arm a, which it carries, has a 
 
DIRECTIONS FOR FILTERING. 355 
 
 circular aperture sloping inwardly and downwards, which sup- 
 ports the funnel steadily in its place. The screw c allows the 
 elevation or depression of this arm at will, as the height of 
 the receiving vessel beneath may require. 
 
 When the funnel is used for transferring or filtering liquids 
 into narrow-mouthed vessels, its barrel may be supported by 
 their neck; but in order to secure a free passage of air it 
 should be fluted externally, or else have a chip or two placed 
 between it and the inner sides of the neck, otherwise the con- 
 fined air will retard the process, and possibly force the filtered 
 liquid, with a hissing sound, up and over the sides and mouth 
 of the bottle. 
 
 After having adjusted the filter to the funnel, the latter is 
 placed in the stand, so that its barrel may rest against the 
 inner wall of the receiving vessel beneath. This position 
 allows the falling fluid to trickle quietly down the sides, and 
 prevents the splashing which would occur if it fell directly 
 upon the surface of the liquid, and also obviates the necessity 
 of sinking the barrel far into the receiver. 
 
 The filtering apparatus having been thus arranged, the 
 filter is to be moistened with distilled water from the bottle, 
 (Fig. 38,) or when the nature of the process requires, with a 
 portion of the solvent liquid, and the excess allowed to trickle 
 through, rather than be emptied out by inverting the funnel. 
 This previous soaking of the filter greatly facilitates the 
 operation, for dry paper absorbs water directly, and in the 
 case of a turbid solution, while becoming more impervious to 
 the suspended particles than it would be if the liquid which 
 contains them were allowed to penetrate at once into the 
 filter, it gives also a more ready passage to the clear fluid. 
 The edges of the containing vessel are now to be slightly 
 greased in one spot, so that in pouring there may be no 
 adhesion of drops or trickling over the sides. It is then 
 grasped by the right hand and brought over the funnel, while 
 the left hand holds the glass rod at a right angle against the 
 edge of the glass as shown in Fig. 317. The end of this rod 
 should merely reach the filter without touching it, for fear of 
 abrasion ; and the liquid should be allowed to flow down its 
 length in a gentle stream at first against the sides, and as the 
 precipitate accumulates it may be allowed to fall in the centre, 
 as there is then less risk of splashing. The filter should never 
 be entirely filled, and as it often requires many pourings to pass 
 
856 
 
 FILTRATION : — POURING. 
 
 the whole of the liquid, great care must be taken in returning 
 the rod to the vessel that nothing be lost. The last particles 
 
 may be rinsed from the vessel and rod by the jet of the spritz 
 bottle A,* (Fig. 321,) by inclining both to the positions shown 
 
 • The spritz, or washing bottle, consists of a twelve ounce vial, to the mouth 
 
 Fig. 318. 
 
 of which is adapted, by means of a perforated cork, a glass tube, drawn out at 
 its upper end as shown in Fig. 318, which represents at the same time its exact 
 dimensions. The bottle is rather more than half filled with water, and by 
 blowing into it through the tube the air is compressed, and when the bottle is 
 quickly inverted it forces out the water through the orifice in a strong jet, which 
 
 Fig. 319. 
 
 Fig. 320. 
 
FILTRATION : — SPRITZ OR WASHING BOTT^LES. 357 
 
 in the drawing below. If any remaining particles still obsti- 
 natelj adhere to the sides of the glass, or of the rod, they 
 
 Fig. 321. 
 
 must be loosened by the feather end of a goose quill, and then 
 washed out as before by the jet of the spritz. When all the 
 liquid has passed through, the precipitate must be washed 
 down from the sides of the filter by the force of the jet of 
 water from the spritz. 
 
 In dusty apartments, both funnel and receiving vessels 
 should be kept covered by circular or square pieces of window 
 glass. The one over the receiver should have an opening in 
 the side for the passage of the barrel or tube of the funnel. 
 
 The receivers are most generally beaker glasses, but cap- 
 sules, flasks, and narrow necked bottles are all made use of. 
 The above precautions refer especially to 
 filtrations in analytic operations. In larger Fig- 322. 
 
 operations the manipulation is not, neces- CZT^Z^ ^-^ 
 sarily, so strict, and when the dimensions of nT V^^^2^;^^^ 
 
 the containing vessel will not admit of con- ^ ^ 
 
 venient handling its contents may be con- 
 veyed to the filter by ladlesfuU in the small porcelain dipper, 
 
 may be directed to any desired point. The bottle complete is exhibited at Fig. 
 319. For washing out beaker glasses, or other deep vessels, a curved jet is 
 more convenient, and is seen at a, Fig. 321. 
 
 When hot water is required the bottle should be of copper, of at least a pint 
 capacity, and of the form presented by Fig. 320. It is heated as directed at 
 p. 231, Fig. 185, and to prevent burning of the hand, is fitted with a non-con- 
 ducting handle. Upon inversion of the bottle the water is driven through the 
 tube d in a. strong jet by the elastic force of the confined vapor. 
 
358 
 
 FILTRATION PROMOTED BY WARMTH. 
 
 Fig. 322. The ladle, during the intervals of the transfers, 
 must rest in a plate and not be placed anywhere in the dust. 
 In order to expedite the process, the liquid, as a general 
 rule, should be allowed sufficient repose previous to filtration, 
 to deposit if possible all its suspended matter, and the clear 
 supernatant portion should be passed through first. The 
 subsident matter being added last, is filtered, as it were, alone, 
 and offers no impediment by obstructing the pores of the filter 
 to the passage of the liquid portion, as it would if mixed with 
 it. As an exception to this rule, certain precipitates which 
 are curdy, gelatinous, flocculent or crystalline, may be filtered 
 immediately after their formation. As warmth usually expe- 
 dites the process, nearly all liquids, when circumstances per- 
 mit, should be filtered whilst hot.* 
 
 * It has already been said that heat promotes filtration; it is even necessary 
 for saturated solutions, which are liable to deposit crystals upon the least dimi- 
 nution of their temperatures. Below are drawings of two kinds of apparatus, 
 convenient for keeping liquids warm during the operation. Fig. 323 represents 
 that known as Professor Hare's filter bath, and consists of an oval copper jacket, 
 flat at top and bottom, with two conical apertures through its body. The cone, 
 with its expanded part directed downwards, is a sort of chimney, under which 
 a spirit lamp is placed to heat the water in the bath, and the other is a bed for 
 the funnel. To prevent ignition of the vapors when inflammable liquids are 
 under process, there is a partition beneath. 
 
 Fig. 323. 
 
 Fig. 324. 
 
 The other drawing. Fig. 324, also shows an apparatus in which there is a 
 metallic casing for the support of a funnel. The neck through which the funnel 
 passes is closed with a perforated cork, and the contained water is heated as 
 shown in the figure. 
 
 Both of these implements are fitted with covers. 
 
FILTRATION THROUGH CLOTHS. 859 
 
 For filtrations of heavy precipitates, or a large amount of 
 liquid, it is advisable to use the filter doubled or even trebled, 
 as it will be thus enabled to resist a very heavy weight. This 
 precaution is necessary also when the liquid runs through a 
 single paper turbid. When only the first runnings are turbid, 
 a single filter will answer for small experiments, but the liquid 
 must be repassed through the same medium. 
 
 Filtration through Cloths. — In large operations, or 
 when the solid matter to be separated is too heavy, or would 
 corrode or clog the pores of paper, the latter is replaced by 
 cloth. The kinds of cloth vary, and each of those already 
 mentioned has its appropriate application. The texture of 
 the medium must be adapted to the consistence of the liquid; 
 for example, flannel or felt may be used for filtering muci- 
 laginous, saccharine and slightly acidulous solutions; twilled 
 cotton or canton flannel for oils; linen and muslin for tinc- 
 tures, vegetable juices and dilute alkaline leys. Sieves of 
 bolting cloth are occasionally used for filtering liquids from 
 very fine or flocculent matters. 
 
 Filters made of the materials above mentioned, and which 
 take the name of strainers, instead of being used like those 
 of paper, are stretched upon square frames formed of four 
 pieces of lath, as shown at Fig. 325. These frames, of which 
 
 Fig. 325. 
 
 there should be several sizes, must be strongly jointed, and 
 should have inserted upon their upper surfaces a number of 
 rectangular hooks, similar to those used in the drying lofts of 
 calico factories for hanging up the printed goods. The cloth, 
 of whatever kind, being cut into a square of size proportioned 
 to that of the frame, is stretched over it somewhat loosely, and 
 retained in position by hitching its margin on these tacks or 
 
360 
 
 FILTRATION THROUGH CLOTHS. 
 
 hooks. This mode is far preferable to that of nailing the 
 cloth down with flat headed tacks, for besides the injury of 
 material, there is less convenience in removing it after the 
 filtration for pressure, or for replacing it with another when 
 it is required. The support for these strainers' is an upright 
 stand. Fig. 326, the interval between the legs of which is 
 suflScient to allow the free entrance of the receiving vessel. 
 
 Fig. 326. 
 
 Fig. 327. 
 
 When the cloths are made into conical bags, as is very often 
 the case, and not without advantage, they are to be suspended 
 by loops to a transverse beam, as shown in Fig. 327. These 
 bags allow the convenience of using narrow mouthed receivers, 
 as the liquid trickles through in a stream from the most 
 depending parts. 
 
 The texture of the straining cloth must be porous, but 
 sufficiently compact to prevent the passage of any solid par- 
 ticles. It is far more convenient than paper for coarse filtra- 
 tion of decoctions, tinctures, oils, syrups, and for separating 
 liquids from solid organic matters. In most instances the 
 cloth or bag may be renovated by washing, and thus be ren- 
 dered fit for other operations. 
 
 Before stretching the cloth upon the frame, or suspending 
 the bags, they should be first moistened with water, or if ne- 
 cessary with a portion of the solvent liquor in order to swell 
 the fibres and contract the meshes. The liquid should be then 
 
FILTRATION THROUGH PULVERULENT MATTER. 361 
 
 introduced gradually without spilling. For this purpose a 
 tinned, copper, or porcelain ladle, Fig. 328, with a wooden 
 
 Fig. 328. 
 
 handle, is very convenient. A very excellent substitute is a 
 dipper, made from a cocoa-nut shell, and sold in any of the 
 furnishing shops. Additions of liquid should be made until 
 the filter is nearly full, and it should be kept at the same 
 level by renewing it as fast as it runs through. If the first 
 runnings are turbid, they should be returned to the filter, and 
 if they continue murky, repassed through a fresh cloth. 
 
 After all the liquid has passed through in this way, the 
 cloth or bag is to be unhooked, carried to a table, securely 
 folded, and enveloped in a wrapper, and subjected to pressure 
 as directed at p. 320, for the expulsion of the retained portion 
 of liquid. The precipitate thus pressed, when an object of 
 value, is to be cut up with a spatula and spread on frames 
 
 for DESICCATION. 
 
 The cloths are then to be immediately rinsed and cleaned 
 in water without soap, dried and placed away for service at 
 another time. 
 
 Filtration through Pulverulent Matter. — Crushed 
 quartz, clean white sand, asbestos, bone black, and charcoal 
 are the materials generally used as media. The two latter 
 act both as filtering and purifying agents, as the liquid be- 
 comes not only clarified in its passage, but freed from color- 
 ing and putrescent matters, if any exist in it. The others 
 are used for the filtration of very acid or corrosive liquids, 
 which would be destructive of paper or cloth, and partially 
 solvent of bone black. 
 
 All of these substances may be used in funnels, a thin stra- 
 tum being placed in the bottom of the body, and prevented 
 from escaping through the barrel by a loose cotton plug in 
 the neck. 
 
 A funnel plugged in this manner, even without the stratum 
 of pulverulent medium, answers an excellent purpose for the 
 filtration of liquids which pass through freely, and whose sus- 
 pended matter is in coarse particles. 
 24 
 
362 FILTRATION OF VOLATILE LIQUIDS. 
 
 It will of course be remembered that the use of these media 
 is only practicable when the liquid is the sole object of value, 
 for it would be impossible to prevent at least the partial ad- 
 mixture of the suspended matter with the secerning agent. 
 
 The asbestos, sand, and charcoal should first be treated 
 with muriatic acid to remove soluble matters, and then tho- 
 roughly rinsed with fresh water to remove all traces of acid 
 previous to their employment as filtering means. Freshly 
 prepared and finely powdered charcoal, by its absorbent 
 power, deprives most liquors of their fetor and organic co- 
 loring matter ; bone black has the same effect, but in a much 
 less degree. These two are the best substances for separat- 
 ing impurities from syrups and aqueous liquids. 
 
 The filtering substance should always, before being used, 
 be moistened throughout, as in displacement, with clean fluid, 
 or, as is proper in many cases, with the pure liquid which is 
 the solvent of the various substances in the fluid which is to 
 be depurated. Thus the substance in the funnel may be made 
 to imbibe water before the filtration through it of a syrup, 
 and alcohol or ether before the passage of tinctures or ethereal 
 solutions. 
 
 Where a natural repugnance exists between the particles of 
 the fluid and of the filter, as is the case with finely divided 
 charcoal of any kind and water — or light aqueous solutions — 
 the solid must be made to absorb the first parts of the fluid by 
 thorough agitation and trituration with it, and then be allowed 
 to separate, previous to its employment, by deposition. In 
 other cases, the pressure of a high column of fluid upon the 
 substance must be allowed to compel the necessary union of 
 surfaces. 
 
 Filtration by displacement, to which the above mode is in 
 some respects similar, has already been fully described at 
 p. 314. 
 
 Filtration op Volatile Liquids. — Donovan has con- 
 trived an apparatus for filtering liquids which are vaporizable 
 or alterable by exposure to air. It is identical in principle 
 and construction with the displacer. Fig. 275, and is very 
 useful for filtering alcoholic, ethereal, or ammoniacal and 
 alterable caustic liquids. 
 
 The modification of Kiouffe is more convenient than the ori- 
 ginal apparatus, as it allows the use of an ordinary funnel with 
 a cover. It is represented by Fig. 329, and consists of a glass 
 
WASHING. 
 
 363 
 
 bottle A, with two necks ; into one of which enters the barrel 
 of the funnel. The neck of this funnel is loosely closed with 
 
 Fig. 329. 
 
 a plug of raw cotton, and the liquid is introduced through the 
 s tube without uncovering or disturbing the apparatus. As 
 the liquid filters through, the column of air displaced, finds a 
 vent through the narrow tube a, adjusted in position by means 
 of perforated corks. The stop-cock K allows the withdrawal 
 of the filtrate at pleasure. 
 
 CHAPTER XXVI. 
 
 WASHING. 
 
 In all precipitations, the powder thrown down becomes 
 involved with more or less of the original liquid from which it 
 has been deposited. As these liquid portions are impurities, 
 
364 
 
 WASHING OF PRECIPITATES. 
 
 Fig. 330. 
 
 they must be separated, and in many large operations, and 
 when the precipitate is bulky, we effect their removal by 
 repeated washing and decantation ; but when the powder is 
 light, and in all cases where accuracy in estimating results is 
 required, the purification is conducted by pouring continued 
 streams of water or other fluid through the substance con- 
 tained in the filter. 
 
 Washing by decantation is usually practiced by diffusing 
 the precipitate in a large quantity of cold or hot water, or 
 other suitable liquid, as circumstances may require or admit ; 
 stirring well, and after sufficient repose for settling, decanting 
 the clear supernatant solution. A repetition of additions of 
 fresh water, and subsequent decantations after repose, will en- 
 tirely remove all soluble matter and free the precipitate from 
 impurity. 
 
 In analyses, the precipitate is most generally washed upon 
 the filter by projecting water from the spritz bottle A, Fig. 321, 
 the jet of which, by its force, at the same 
 time loosens that portion adhering to the 
 sides, and concentrates it all at the bottom, 
 when a larger amount of washing liquid 
 may be added from the bottle. Fig. 38. 
 To give force to the issuing jet, as is some- 
 times necessary in detaching particles from 
 the filter, the tubes of the spritz may be as 
 shown in Figs. 330, 331. The compression 
 of the air in the interior by blowing in the 
 tube a produces a jet through the lateral 
 one 6, drawn out to a small orifice. This 
 form of spritz is much more convenient for 
 large filters than the smaller one. Fig. 319, 
 either, however, allowing the direction of 
 the stream to any desired part of the filter. 
 The above mentioned bottle is flat bottomed, and of thin glass, 
 so as to answer for the use of boiling liquid. 
 
 The copper flask, Fig. 186, with tubes fitted to its mouth 
 as above described, is, however, far more convenient, and less 
 liable to receive injury. 
 
 The precipitate being in this manner kept constantly min- 
 gled with liquid, is soon freed from its soluble matter. The 
 latter fact is known when a drop of the wash-liquor, which 
 
edulcoration; — washing bottles. 
 
 865 
 
 has passed through, leaves no stain upon a silver or platinum 
 spatula heated over the spirit lamp. 
 
 Fig. 331. 
 
 There are many precipitates which require protracted wash- 
 ing, or edulcoration^ as it is sometimes termed, in order to 
 cleanse them thoroughly, and the bottle for the purpose is so 
 
 Fig. 332. 
 
 Fig. 333. 
 
366 edulcoration; — washing bottles. 
 
 constructed as to be self-operating in a measure, this mode 
 being a great saving of time and labor to the operator. 
 Fig. 332 represents the whole arrangement, which is so con- 
 trived that by a suitably constructed tube J, adapted by 
 means of a perforated cork to the flask or bottle a, the water 
 therein contained flows out very gradually, and in quantity 
 proportional to its passage through the filter. The tube is 
 that known as Gmelin's. It is well replaced by two separate 
 tubes, which can be readily formed over the blow-pipe flame 
 by the operator himself; the modified implement is shown at 
 Figs. 333, 335. 
 
 Below are the two forms of washing tubes, both acting upon 
 the same principle. Fig. 334 represents the one devised by 
 Berzelius, and Fig. 335 that of Gmelin's. 
 
 The mode of washing by these bottles is very convenient. 
 They are nearly filled with water, and inverted over the 
 funnel in such a position that the part c extends below the 
 surface of the liquid and no further. The flow continues in 
 a constant current without further attention until the surface 
 of water in the filter rises towards the line ef, Fig. 335, and 
 diminishes the pressing column, when capillarity is in excess 
 and no more water flows. But as the water slowly percolates 
 through the filter, the column is increased, and the water again 
 flows. This alternate action is continued until the bottle is 
 emptied. 
 
 The great convenience of this arrangement is that a filter 
 may be washed during the absence or inattention of the ope- 
 rator. 
 
 If the precipitate is soluble in water, it must be washed with 
 alcohol, ether, or other liquid which is without action upon it. 
 
 When the bottle filled with water is inverted, as in Fig. 332, 
 there will be no efllux of water from the small opening c, Fig. 
 335, so long as this point is at a certain distance below the 
 curve of the syphon; but if the moistened finger, or other 
 body, be held to the point c, water will flow freely from it, 
 and air bubbles will ascend through i h to supply its place. 
 If the tubes and opening were of large size, the water would 
 flow out with touching the end of the tube, but being of small 
 diameter, and the end c being drawn out finely, the eflSux of 
 water is opposed by capillary attraction. The column of water 
 between e f and g his the force tending to overcome the capil- 
 lary resistance. If this column be lengthened by drawing e d 
 
BLOWPIPE MANIPULATION, 
 
 367 
 
 further through the cork, then the water will flow out of e 
 spontaneously, li cdhQ pushed in just so far that the water 
 
 Fig. 334. 
 
 Fig. 335. 
 
 \U 
 
 does not flow spontaneously, then the capillary resistance 
 slightly predominates. Then if a substance to which water 
 adheres by adhesive attraction, be applied to the end of <?, it 
 will make the water flow so long as it is held there, because the 
 adhesive attraction of the touching overcomes the capillary 
 action. 1^ c dhe thrust still further into the cork, then capil- 
 lary action predominates so greatly that no adhesive force can 
 counteract it, and the water will consequently not flow out. 
 There is, therefore, a particular medium position for the point 
 <?, where it will act as desired. 
 
 CHAPTER XXVII 
 
 BLOWPIPE MANIPULATION. 
 
 Many substances come under the observation of the chemist, 
 of the nature of which the physical properties furnish but little 
 indication; and as a preliminary examination called Qualita- 
 
368 USE AND CONSTRUCTION OP THE BLOWPIPE. 
 
 five Analysis, should in such cases be made to precede the 
 Quantitative Analysis^ — in order that from a knowledge of the 
 constitution of the body, a mode of effecting the latter process, 
 or the determination of the amount of its constituents, may be 
 devised — it becomes very important to be provided with a means 
 of simple and rapid examination, and one of general applica- 
 tion. 
 
 Such means are presented by the mouth blowpipe, which is 
 simple in construction, cheap, portable, and which not only 
 furnishes to those who are at a distance from, or unfurnished 
 with chemical apparatus, the power of determining the cha- 
 racter of minerals and other bodies, but when employed as an 
 adjuvant to other methods, enables us frequently to appre- 
 ciate with exactness and ease the most minute quantities of 
 simple bodies, or the ingredients of those which are complex. 
 Even in analyses in the humid way, we are often obliged to 
 resort to it, in order to be enabled to ascertain the existence 
 of a substance, the presence of which in solution cannot be de- 
 termined by any tests. 
 
 The blowpipe is employed for the purpose of forcing a fine 
 stream of atmospheric air through the flame of a candle or 
 lamp, so that the continuous current or blast produced, shall 
 impel in a proper direction, the flame, and furnish to the par- 
 tially burnt particles of carbon of which it in a measure consists, 
 enough oxygen to cause vivid combustion and great heat. 
 The simplest form of a blowpipe, and the one originally adopt- 
 ed, is that used by gas-fitters, jewelers, and others, for 
 Fig. 336. the purpose of soldering, &c. It is represented in 
 cc-^ Fig. 336, and consists of a metallic tube, usually made 
 \\ of brass, somewhat curved at a short distance from its 
 tapering extremity. The bore terminates in a very 
 small perforation, with a rounded margin. 
 
 This instrument is used by propelling a rapid and 
 steady blast of air through the tube from the mouth, 
 by the action of the muscles of the cheeks, and by 
 directing this blast against the side of the flame. The 
 blowpipe of this form is still preferred by artificers for 
 operations in which little blowing is needed ; but when 
 the process is of some duration, the moisture of the breath 
 gradually condenses in the tube, and impedes the blast, or else 
 the latter forces some of the aqueous matter through the flame 
 upon the substance which is under examination, thus consti- 
 
wollaston's blowpipe. 
 
 869 
 
 tuting serious objections to its employment for analytical 
 purposes. 
 
 Of all the modifications of this instrument, that of the cele- 
 brated Gahn is by far the best, and to it almost universal pre- 
 ference is given. Before proceeding to speak of it, however, it 
 may be well to refer to the ingenious contrivance of Dr. Wol- 
 laston. It consists of three pieces, «, 5, and <?, Fig. 337. The 
 small end of the tube a fits in the large end of h. The 
 latter is closed at the other and narrower extremity, and a 
 short distance from it, a small hole, dy is pierced transversely 
 through the tube. 
 
 Fig. 337. 
 
 Fig. 338. 
 
 n ' 
 
 U 
 
 The difierent parts of the instrument are represented to 
 better advantage in Fig. 338. The smallest piece, c, which 
 has its short end closed, is slid over the top of 5, by means of 
 the oblique hole (?, in such a manner that the small hole d will 
 
370 gahn's blowpipe. 
 
 communicate with the fine conduit in the narrow end of the 
 former piece. This instrument possesses the great advantages 
 of being compact and portable, for when properly constructed, 
 all its pieces will exactly fit in each other, and when closed 
 the whole is scarcely larger than a pencil case. It is shown 
 thus packed up in the figure. The objections to it are that it 
 contains no air chamber, or suitable reservoir for retaining the 
 condensed moisture, and that the direction given to the blast 
 in consequence of the angle formed by the piece c with 5, 
 is such as to prevent the operator from properly seeing the 
 substance of which he is investigating the properties. 
 
 Gahn's admirable instrument shown in Fig. 339, combines 
 the advantages of all former inventions. 
 
 Fig. 339. 
 
 A long and slightly conical tube fits in a cylindrical chamber 
 which is one inch in length, and half an inch in lateral diame- 
 ter, and which is designed to condense and retain the moisture. 
 In the side of this cylinder is inserted another and shorter 
 tube, which makes a right angle with the large one, and which 
 is considerably less in size. That end of it which is introduced 
 into the flame is protected by a tip of platinum. This 
 Fig. 340. tip is nothing more than a small conical piece of 
 
 A platinum, of the form represented in Fig. 340, which 
 
 ^ can be placed over the end of the tube, and which 
 has a perforation as fine as the point of a needle. 
 
 This metal is preferred on account of its infusibility, and 
 of the ease with which a common impediment to the operation 
 — the clogging of the mouth of the tube with finely divided 
 soot — can be removed, when the extremity is made of it. All 
 that is necessary to get rid of this deposit, is to subject the 
 clogged tip of the tube to the action of a high heat, produced 
 by the use of the same blowpipe, and which burns ofi" the 
 carbon. Tips made of silver answer a very good purpose, and 
 are often used; but they are apt to become brittle and crys- 
 
MITSCHERLICH S BLOWPIPE. 
 
 371 
 
 talline in texture upon cooling, after exposure to a high red 
 heat. 
 
 When moisture collects in the chamber of this instrument, 
 it can be expelled by simply disconnecting the joints, blowing 
 forcibly through the tube, and by the application of a dry 
 cloth. 
 
 Mitscherlich has made an improvement upon Gahn's blow- 
 pipe, which renders it more portable. He reduced the size 
 of the chamber and fastened it permanently to the long 
 tube. This tube is made to unscrew in the middle, so that the 
 small tube c, with its platinum jet D, can be slid into the part 
 connected with the chamber, and the other half A, can be 
 fitted upon B, so that the whole makes an instrument little 
 inferior in portability to Wollaston's, as shown at F. The 
 little nozzles adjusted upon these instruments* can, in a mea- 
 sure, be dispensed with if care is taken to remove the blowpipe 
 from the flame the moment the blowing is suspended. When 
 the small orifice becomes filled with soot it can be reopened 
 by introducing the point of a needle, which has been held for 
 a short time in the flame. If this latter precaution is not 
 attended to, the point is apt to snap off, and sometimes great 
 
 Fig. 341. 
 
 Fig. 342. 
 
 difficulty is experienced in removing it, and risk incurred of 
 injuring the instrument. 
 
 They are preferred for cheapness, and should be silvered or platinized. 
 
372 
 
 ECONOMICAL BLOWPIPE. 
 
 Dr. Black's is the most cheap form of metallic blowpipe, 
 and is shown in Fig. 342. It is a conical tube of japanned 
 tinned iron plate, closed at the wide extremity; near which, 
 upon the side, is adapted a brass tube with a nozzle of proper 
 size. 
 
 Silver and tinned iron are the proper materials for the 
 construction of blowpipes. Copper, brass, and German silver 
 are employed, but being exposed both to heat and moisture, 
 they oxidize easily, and give an unpleasant odor to the hands 
 and brassy taste to the mouth. 
 
 Necessity may compel the student to make a blowpipe of 
 his own construction. In such a case, a common 
 Fig. 332. clay tobacco pipe may be converted into one by 
 closing the bowl with a cork, in which is fitted a 
 glass tube, with one end drawn out to a small 
 orifice. It is economical and convenient, and 
 considering the fragile material of the exit tube, 
 answers the purpose admirably. 
 
 One of the best blowpipes we have ever seen 
 employed was constructed in this way, except 
 that the small tube was made by filling the end 
 1 '^^--^ of the bore of a broken tobacco pipe, firmly with 
 \..^/ci^ common putty, and then piercing the plug thus 
 made with a pin or needle, and allowing it to dry. 
 This expedient succeeds very well, and although the instru- 
 ment is clumsy in appearance, the extremity is not fusible 
 like glass, and with a little skill the whole may be so fashioned 
 as to make a most serviceable apparatus. 
 
 Entire blowpipes are also readily made from glass tubes. 
 The material is cheap, and the requisite form can be easily 
 given them; but notwithstanding these advantages, their use 
 is very limited, in consequence of their brittleness, and the 
 ease with which the point of the small tube fuses. 
 
 The blast from the blowpipe is directed upon the flame of a 
 wax or tallow candle with a cotton wick, or that furnished by 
 coal gas or an oil lamp. If a candle is employed, Bergmann 
 directs that the wick be inclined to one side towards the 
 object, i. e. in the direction in which the flame is to be im- 
 pelled. Besides not always giving sufiicient heat, candles 
 have the disadvantage of consuming too rapidly, since the wax 
 or tallow readily melts from the heat which is radiated from 
 the substance in the flame. The wick also requires frequent 
 
BLOWPIPE LAMP AND APPLIANCES. 
 
 373 
 
 trimming. The lamp recommended by Berzelius, with the 
 improvements of Harkort, gives the best flame for these ex- 
 periments, and has a very convenient form. It is seen in 
 Fig. 344. It is made of brass,* has a length of 4 J inches, is 
 
 Fig. 344. 
 
 |fi^^^ 
 
 of a slightly conical shape, and is an inch in diameter at the 
 lower end, which is furnished with a screw to adjust it to the 
 brass rod, which is fastened to metallic cross pieces, so as to 
 support it in its perpendicular position. The screw enables 
 the operator to raise or lower the lamp to suit his convenience. 
 On the upper side of the lamp, at one end, is an opening for 
 pouring in the oil, closed by a screw cap with a leather washer. 
 Near the other end is the wick holder, a piece of tinned iron 
 of a rectangular form, which is inserted in a brass screw per- 
 manently connected with the lamp. The direction of the 
 wick holder is parallel with the lamp. When not in use a 
 screw cap with a washer is adapted to the corresponding screw, 
 and surrounds the wick, closing it hermetically, so as to prevent 
 .the escape of oil in transportation. The object of the obliquity 
 of the front of the lamp is to permit a considerable deflection 
 of the flame when it is desired to bring the assay nearer to 
 the source of heat, as is sometimes necessary. Fig. 345 
 represents the cap covering the wick, and gives a view of the 
 position of the cross pieces forming the support of the lamp. 
 
 Tin plate may be substituted. 
 
374 
 
 BLOWPIPE : — FLAME. 
 
 Fig. 345. 
 
 The rod can be unscrewed in the middle, the cross pieces 
 disunited, and all the parts separated, so that the whole can 
 be packed away and made to occupy very little space. 
 
 This lamp is fed with pure olive or refined rape oil, which 
 is decidedly the best. For the stationary blow- 
 pipe table in the Laboratory, coal gas is used, 
 and is supplied by a leaden pipe with a nozzle 
 of brass, similar in form to the wick holder of 
 the lamp ; it does not furnish the same amount 
 of carbon for combustion as the above named 
 liquids, but is preferred on account of its clean- 
 liness. The triangle. Fig. 344, with the bars , 
 attached to the arm which moves laterally, 
 by a screw capable of being moved upon the 
 upright, is for the support of vessels, such as 
 small crucibles, over the flame. Different sized 
 crucibles can be made to fit in this triangle by 
 removing one or more of the bars. 
 
 In some cases the common spirit lamp. Fig. 115, before de- 
 scribed, is used to furnish the flame. It answers particularly 
 well for the heating of glass tubes when it is desirable to avoid 
 a deposit of soot upon the surface. 
 
 The Flame, — The flame of a common candle or oil lamp con- 
 sists of four distinct parts. The part within a b, 
 Fig. 345, surrounding the wick at the point where it 
 commences to burn, of a beautiful blue color, which 
 becomes thinner as it ascends from the wick, and a 
 small distance from it disappears entirely; a very 
 dark central portion c, having a conical shape and 
 surrounded by c?, the brilliant part of the flame 
 through which the former is distinctly seen ; and, 
 finally, the external faintly luminous lamina, a and 
 h, which, becoming broader near the apex of the 
 flame, envelops the whole. 
 
 These different appearances are accounted for 
 in the following way. The wick — which, after its 
 combustion has melted the upper portion of the 
 fatty matter, is merely the agent for the imbibi- 
 tion and passage upwards by capillary attraction, of the 
 fluid combustible — gives off at its ignited extremity the in- 
 flammable gases and possibly some carbon, into which the 
 fat has been resolved. These gases, not meeting with a suflS- 
 
 Fig. 346. 
 
BLOWPIPE : — FLAME. B75 
 
 cient supply of oxygen, rise and form the central dark cone; 
 upon the outer surface of which, however, the hydrogen con- 
 tained in them may be supposed first to combine with the 
 oxygen of the air, to the production of an intense heat, by 
 exposure to which the carbon which had been unconsumed is 
 heated to whiteness; the latter thus forming the brilliant 
 luminous portion of the flame by its ignition, and more or 
 less complete union with oxygen. The external envelope of 
 faintly luminous matter is probably owing to the complete 
 combustion in contact with air, of those portions of gaseous 
 matter which had not been previously burnt. This part, 
 considered in reference to its whole surface, is the hottest 
 portion of the flame, but the maximum of heat is given 
 ofi^ at the level of // in the Fig., and from that part it gra- 
 dually decreases to the apex and the base. The combustion 
 of a little carbonic oxide, and possibly some carburetted 
 hydrogen, gives rise to the blue portion of the flame seen at 
 a, h. This is the coolest part of the flame. 
 
 A stream of air projected into the flame makes it present 
 a very difi*erent appearance. Before the 
 nozzle of the blowpipe, is formed a blue, ^^s- 347. 
 
 well defined, long and slender cone, which /^ •^ 
 
 is similar in appearance to that in Fig. 346. ^E^ 
 
 The hottest point in the flame thus excited 
 is just before the point of the cone. Exte- 
 rior to it is a yellowish-brown flame a c, 
 somewhat luminous, but undetermined in 
 outline. It is in this flame a little beyond 
 the point of the blue cone, that reduction is effected. For 
 oxidation we must remove the body from the outer flame just 
 so far as the temperature is consistent with the object in view, 
 i. e. at such a distance in advance of the inner flame, as is best 
 calculated to oxidize. But as metals differ in their affinity 
 for oxygen, this point can only be ascertained by practice. 
 
 The former is called the reducing flame, because in conse- 
 quence of an excess at its extremity, of burning carbonaceous 
 matter, which greatly absorbs oxygen, the oxide of a metal, 
 if employed, is deprived of its oxygen, or in other words, is 
 reduced to the metallic state. One object of the blow-pipe is 
 to supply oxygen, which is always contained in air expelled 
 from the lungs, so as to burn off the hydrogen of the flame 
 and to set free the carbon and carbonic oxide in order to re- 
 
376 
 
 THE MANNER OF HOLDING THE BLOWPIPE. 
 
 duce the reducible body exposed to its action. It is also the 
 co-operation of some unconsumed carburetted hydrogen that 
 assists in the reduction. 
 
 The Manner of Holding the Blowpipe. — The cut, Fig. 
 348, represents somewhat imperfectly the proper mode of 
 
 Fig. 348. 
 
 holding the blowpipe and support, and of directing the flame 
 upon the object on the latter. The former is held like a pen 
 between the thumb and first two fingers of the right hand, 
 and its mouth-piece is inserted between the lips. The sup- 
 port is held in a convenient position by the left hand, and 
 both arms should be so fixed upon the elbows, or otherwise, 
 without reference to a particular fashion of holding them, as 
 to ensure that the object be kept constantly in one place 
 under the continuous blast from the blowpipe. 
 
 The Blast. — A uniform current of air is expelled through 
 the tube from the lips, by making the mouth and lungs act 
 upon the same principle as the ordinary table blowpipe, which 
 has been before fully described. The lungs acting like the 
 piston, force by their alternate contraction and dilatation, an 
 intermitting current of air into the cavity of the mouth ; which 
 being analogous to the condensing box of the large blowpipe, 
 by the constant pressure and elasticity of its muscular walls, 
 converts the alternating into a continuous blast. The be- 
 
BLOWPIPE MANIPULATIONS : — SUPPORTS. 377 
 
 ginner finds great difficulty in properly regulating this part 
 of the process, and some never acquire the necessary tact. It 
 is an accomplishment which experience and practical instruc- 
 tion alone can give, and which no description can impart. 
 The blast is first forced through the tube by filling the mouth 
 with air, expanding the cheeks, and then keeping up a con- 
 stant and forcible pressure with the muscles forming their 
 parietes, at the same time that respiration through the nose 
 is allowed to go on calmly and uniformly as usual. But as 
 the current constituting the jet is required to be uniform, it 
 must be prevented from sharing in the alternating impulse 
 communicated from the lungs, by a valve-like closure of the 
 opening of the mouth into the throat ; which closure becomes, 
 with a little practice, an instinctive act. When the mouth is 
 nearly emptied of its air, this communication is temporarily 
 reopened without any intermission of the blast, the cavity is 
 refilled, and the communication again closed until the next 
 occasion for its opening. 
 
 Supports. — The substance under examination, must be al- 
 lowed to rest firmly upon a support, which should be such as 
 will not fuse under a high heat, combine chemically with the 
 fused body, or prevent its complete heating by rapid conduc- 
 tion. The supports in most common use are charcoal, and 
 platinum either in the state of wire or foil. 
 
 Charcoal makes, for many operations, an excellent support, 
 especially that kind of it which is made from well-grown pine 
 wood or the branches of the willow. It should be well charred, 
 and that which snaps or smokes in the fire should be rejected. 
 It is desirable that it should be as free as possible from ashes, 
 which nearly always contain a trace of iron and manganese; 
 therefore dense and compact woods should not be used, as they 
 give much ashes, and often contain a considerable amount of 
 those oxides, which by uniting with the fluxes employed, would 
 give incorrect results. Straight pieces, free from knots, should 
 be sawn in the direction of the fibres, into oblong supports of 
 the proper size. The assay is placed in a shallow concavity 
 made near one end of such a support by the borer or point of a 
 knife ; and upon this substance, so prepared, oxidation, reduc- 
 tion and fusion are chiefly performed. 
 
 Sometimes the reducing property of charcoal, and the 
 rapidity with which it is (Sssipated into carbonic acid, inter- 
 25 
 
378 BLOWPIPE MANIPULATIONS : — SUPPORTS. 
 
 fere with the result. In such cases platinum in the form of 
 foil or wire is used. A narrow strip 3 inches long and J inch 
 broad is often advantageously employed for oxidation. The 
 substance which is to be oxidized, is placed on it near one end, 
 and heat is applied by the blowpipe flame upon its under side. 
 Its conducting power is so inconsiderable that the other end may 
 be held between the fingers without inconvenience. Platinum 
 cannot in general be used for reduction, as it forms fusible 
 alloys with some of the metals ; nor should sulphurets, arse- 
 niurets, &c., be heated in contact with it. When the strip is 
 too short to be held between the fingers, it can be inserted in a 
 piece of wood or charcoal, or be held between the points of the 
 pincette. A small spoon of the same metal is sometimes 
 made use of; but in the majority of cases the wire may be 
 substituted for any other means. 
 
 When platinum wire is used, it should be moderately thin, 
 and have a length of about 2J inches, and should be 
 Fig. 349. bent into a hook at one end, which serves as the sup- 
 1 port for the assay. This part is either heated for a 
 moment in the flame or moistened by the tongue, and 
 dipped into the flux, whereby a small quantity becomes 
 attached, which, when fused to a transparent bead by 
 the blowpipe flame, becomes firmly fixed in its bed 
 and occupies the space within the curve. The side of 
 the bead is then mi)istened and a little of the assay 
 is made to adhere to it. 
 Both are now fused together, and the appearance of the 
 bead held in one or the other part of the flame, in reference 
 to opacity, color and other characteristics, can be distinctly 
 seen from all sides, and in this way are colorations of the 
 bead by metallic oxides particularly to be distinguished. The 
 only objection to this hooked wire, occurs in the case of the 
 use of fusible flux, which is apt to fall through it. Two 
 or three additional turns of the hook will generally make a 
 bed suflficiently close to prevent this salt from running through 
 when fused. 
 
 The bead can be detached from the wire, when cold, by a 
 slight blow with the hammer. If, after its removal, the wire 
 is not left perfectly clean, a bead of soda may be fused upon 
 it, and afterwards dissolved out, when it takes the impurities 
 with it. In extensive investigations by means of the blow- 
 pipe a number of these wires should be provided. 
 
DETECTION OF VOLATILE SUBSTANCES. 
 
 879 
 
 Detection of Volatile Substances by means of the Blow^ 
 pipe. — When volatile substances or gaseous products are to 
 be tested by means of this instrument, the body to be ex- 
 amined is usually exposed to heat in an open glass tube, which 
 may be from two to four inches in length, and from the 
 twelfth to the third of an inch in diameter. The body is placed 
 near to one end and the blast is directed upon it, while the 
 tube is inclined more or less in proportion to the current of 
 air, which is required to be passed through it. By such 
 means, disengaged vapors may be sometimes recognized as 
 they emerge from the upper end, and volatile matters con- 
 densed upon a part of the tube. 
 
 It is often necessary to deposit the substance in the angle 
 of a curved tube so as to prevent it from falling out. A tube 
 so bent is shown at 5, Fig. 351. Another modification is re- 
 
 Fig. 350. 
 
 Fig. 351. 
 
 quired where the access of much or any air would counteract 
 the intention of the operator, by oxidating the body. In such 
 cases the lower end of the tube is either completely closed, 
 or drawn out to a fine orifice as at c in the same figure. A 
 tube of this form is well adapted to the sublimation of sele- 
 nium from a sulphuret, where the entrance of much air would 
 oxidize it. Decrepitating substances should also be heated 
 in tubes closed at one end, and should be so inclined as to 
 avoid loss of particles. For such and many other purposes 
 tubes. Fig. 168, enlarged into a bulb at one extremity are 
 very appropriate. 
 
 All the glass tubes and vessels employed in this way should 
 be perfectly free from lead. 
 
 The following instruments are also used in making examina- 
 tions with the blowpipe. Steel forceps with the points made of 
 platinum, for holding the assay in the blowpipe flame to as- 
 
380 
 
 INSTRUMENTS USED IN BLOWPIPE ANALYSIS. 
 
 certain its fusibility or other properties when exposed to an 
 elevated temperature. The two upper figures of the cut re- 
 present different views of an excellent forceps, capable of very- 
 general application. Two strips of steel, with narrow pla- 
 tinum points 6, h, are fastened in the middle by a piece of 
 metal seen at e, e. These strips separated, as seen in the 
 
 Fie. nr>g. 
 
 figure, constitute a double pair, one being at a, a, and the 
 other at e. The platinum points by the elasticity of the 
 metal of which the forceps are made, are always closed. To 
 open them it is only necessary to compress with the thumb 
 and finger, the small projections with the button heads d, d, 
 which are connected with the strips opposite to them. Upon 
 relaxing the pressure, the assay is forcibly held between the 
 points. The points a a are tempered, and are used for de- 
 taching exceedingly small fragments of the mineral. 
 
 Another form of this instrument is employed, but its use is 
 not quite as convenient as that of the one just mentioned. Its 
 points b c are also of platinum, but curved a little, as repre- 
 sented in the figure. The legs are made of brass. The for- 
 ceps is kept open by the elasticity of the metal, and closed 
 by a double button d, which slides up and down in a slit cut 
 in the legs. As brass is a good conductor of heat, two pieces 
 of wood e e are fixed to the legs, by which the instrument is 
 held, to prevent any inconvenience to the hand. Under this 
 
INSTRUMENTS USED IN BLOWPIPE ANALYSIS. 381 
 
 last forceps, is still another made, of iron, which can be 
 used for a variety of operations, and which is not solely con- 
 fined to this application. Substances to be held very firmly 
 are placed between the points. It has a button d d, with a 
 steel spring d e, to prevent the forceps from opening by the 
 sliding back of the button. 
 
 A Microscope. — A plano-convex microscope, with two lenses 
 of different magnifying powers, is often useful in minute ana- 
 Fig. 353. 
 
 lysis, and one is i*epresented in Fig. 353, which is made to 
 fit in a small receptacle. By its aid, the minute structure of 
 bodies, and fine colors imparted to the fluxes or to charcoal, 
 which often deceive the naked eye, are examined. 
 
 Charcoal Borer. — A conical tube of tinned iron with the 
 margin filed to a sharp edge, for making cavities in the char- 
 coal support, is often made to occupy a place in blowpipe 
 apparatus. It answers very well as a case to contain a phial 
 as shown in the figure above. 
 
 A pair of cutting pliers is used to clip off small particles 
 
 Fifr. 354. 
 
 of minerals, and pieces of a metal or alloy for examination, 
 and for many other purposes which will suggest themselves 
 
382 
 
 INSTRUMENTS USED IN BLOWPIPE ANALYSIS. 
 
 to the experimenter. A clasp is attached to the handles for 
 the purpose of keeping them forcibly closed. 
 
 The Hammer and the Anvil, — A polished hammer of hard- 
 ened steel, Fig. 355, with a square, even surface at one end. 
 
 Fig. 355. 
 
 Fig. 356. 
 
 and the other terminating in an edge with sharp corners, is a 
 very necessary implement. The flat surface is very appli- 
 cable for flattening globules of reduced metals, and the edge 
 for breaking off" small pieces of minerals. Very small frag- 
 ments can be broken ofi* without doing any injury to the re- 
 maining portion, which is often kept as a specimen. 
 
 A necessary accompaniment to the hammer is the anvil, 
 
 which is represented in Fig. 356, 
 in a most convenient and com- 
 pact form. It is made of steel, 
 and is usually about three inches 
 long, one inch in thickness and 
 five-eighths of an inch in breadth, 
 and any one of its surfaces can 
 be used. The substance to be 
 broken up, or the metallic globule to be flattened out, is enclosed 
 in thin paper, and having been placed upon the anvil, is struck 
 with the hammer until the proper effiect is produced. If the 
 substance is reduced to powder, the paper prevents any of it 
 from being scattered or lost. 
 
 The Mortar and Pestle, — These implements, made of agate, 
 are of small size, and have been described at page 79. They 
 should be hard and perfectly free from holes and cracks, or 
 they will be liable to fracture and to the filling up of their 
 crevices with the powdered materials — much to the detriment 
 of future operations. 
 
 An Electroscope and Magnetic Needle Case. — A cylin- 
 drical wooden box is used to contain Haiiy's electroscope and 
 a magnetic needle. 
 
INSTRUMENTS USED IN BLOWPIPE ANALYSIS. 883 
 
 The former consists of the hair of a cat, Fig. 357. 
 
 insulated by being inserted in sealing wax I 
 
 poured into the bore of a small glass tube. r-^ 
 
 This tube is fastened in a wooden screw, <!=> 
 which closes one end of the case. It is so 
 
 ^ 
 
 delicate that a very small quantity of elec- 
 tricity is discovered by its aid. On bring- 
 ing it near to an excited body, it is attracted by it ; but if ne- 
 gative electricity is developed in it, by rubbing or drawing it 
 rapidly through the fingers, and it is then brought in proximity 
 to the excited body, it will be attracted or repelled in accord- 
 ance with the existence in that body of positive or negative 
 electricity. In the screw at the other end (each one serving 
 as a stand), is fixed a similar tube and sealing wax to insu- 
 late a small steel pin, which supports a magnetic needle con- 
 tained in the box. The needle is mounted with an agate cup 
 to prevent friction as much as possible, when suspended on 
 the point of the pin. In this condition, it is used to indicate 
 the presence of iron when it exists in a mineral in an appre- 
 ciable quantity, and also the magnetic condition of iron ores. 
 Minerals, before and after being submitted to the action of 
 the blowpipe, should be examined in regard to these pro- 
 perties. 
 
 A Steel Magnet. — This is employed in the mode recom- 
 mended by Haiiy to ascertain whether the slightest trace of 
 magnetic force exists in minerals, and consequently whether 
 the metals in which that force exists are present. The expe- 
 riment is thus performed. The magnet is placed at a small 
 distance from a suspended magnetic needle, its north pole 
 being directed towards that of the needle ; it is then gently 
 moved around the needle until the latter takes a position at 
 right angles to its former place, owing to the repulsion of the 
 same kind of magnetism. This repulsion, and the force of ter- 
 restrial attraction which tends to make the needle return to its 
 former direction, now hold the needle exactly balanced between 
 them, so that the smallest disturbing magnetic force moves it 
 out of its place. In this way an amount of magnetic influence 
 may be detected, which would not be sufficient to affect the 
 needle in its ordinary state. In performing this experiment, 
 care must be taken not to excite electricity in the mineral by 
 friction, as that force might affect the result more or less. 
 
 A knife of good hardened steel is used for trying the com- 
 
384 INSTRUMENTS USED IN BLOWPIPE ANALYSIS. 
 
 parative hardness of metallic bodies and minerals generally. 
 It may be used as a charcoal borer, and if well magnetized 
 can be substituted for the magnet. The point is used to take 
 up the fluxes before mixing them in the palm of the hand with 
 the mineral which has been pulverized for examination. 
 
 Files are convenient for detaching small particles of a metal 
 which is to be investigated, cutting glass tubes, and for trying 
 the hardness of bodies. They may be of different shapes, 
 and should be kept clean and out of the reach of corrosive 
 vapors. 
 
 An Edulcorator or spritz. Fig. 319. This is used to 
 wash the charcoal from the reduced metal. It is necessary 
 to be very cautious in doing this when the metal is small 
 in quantity, as the force of the jet may carry the latter away 
 with the charcoal. A pipette or dropping tube, made by 
 drawing out in the flame of a candle or spirit lamp one end 
 of a glass tube to a small opening, can be used with more 
 impunity. The separation will be facilitated by reducing to 
 powder, in the agate mortar, the charcoal adhering to the piece 
 of metal, as the globule, if malleable, will be thus slightly flat- 
 tened and made more distinctly visible. 
 
 Small capsules of porcelain or watch glasses, are useful for 
 receiving temporarily the results of the experiments ; such as 
 specimens of reduced metal, the colored beads, &c., and for 
 keeping separately, different fragments of the minerals to be 
 investigated. 
 
 A small pair of scissors, a thin saw with fine teeth for 
 sawing pieces of charcoal, a pair of small tongs for holding 
 crucibles, &c., over the spirit lamp, a small capsule of plati- 
 num, a touchstone with needles of gold and alloys of different 
 standards for trying the fineness of gold, will all be found of 
 occasional use. 
 
 Fig. 358. 
 
 The Box containing the Reagents. — As it is necessary to 
 have the fluxes always ready for use, Gahn contrived a con- 
 
BLOWPIPE MANIPULATION : THE REAGENTS. 385 
 
 venient and portable box for the purpose, which is seen 
 in Fig. 358. It is 8 J inches long, 1/g broad, 1 inch in 
 height, and is divided into nine compartments to receive the 
 different reagents. Each division has a lid nicely closing its 
 particular box so as to prevent any one substance from becom- 
 ing mixed with the others. A common lid closes over these 
 smaller ones and is fastened to the box by two hooks. The 
 cross pieces, which are permanently fixed to the large lid, fit 
 into spaces between the 2d and 3d lids from each end, and 
 serve to make them more secure. If more reagents are re- 
 quired than can be contained in these boxes, those which are 
 but seldom used may be wrapped in paper and placed in one 
 of them. 
 
 The Reagents. — The reagents, which must all be chemically 
 pure, are the following: — 
 
 Carbonate of Soda, commonly called soda, which is much 
 used to detect the presence of silica, to assist the reduction of 
 metallic oxides, and generally, to determine whether a body 
 unites with it to the production of a fusible compound. 
 
 Cyanide of Potassium. — This substance being very deli- 
 quescent, should be kept as free as possible from contact with 
 humid air, and had better be placed in a small, tightly corked 
 test tube, which may have its place in one of the small com- 
 partments of the box. 
 
 As a blowpipe reagent, cyanide of potassium is highly use- 
 ful; its action is indeed extraordinary. Substances like per- 
 oxide of tin, sulphuret of tin, &c. &c., which for their reduc- 
 tion with carbonate of soda, require rather a strong flame, are 
 reduced with the greatest facility when cyanide of potassium 
 is used. In blowpipe experiments we always use a mixture of 
 equal parts of carbonate of soda and of cyanide of potassium, 
 since the latter alone fuses too easily. This mixture, besides 
 its more powerful action, has another advantage over carbonate 
 of soda : it is with extreme facility imbibed by the porous char- 
 coals, so that the purest metallic globules are obtained. 
 
 Bihorate of Soda. — This salt, which is commonly called 
 borax, is used to facilitate the fusion of very many substances. 
 When melted with the metallic oxides, its bead assumes a 
 great variety of colors, which furnish excellent indications of 
 the presence of the metals. 
 
 Phosphate of Soda and Ammonia. — This substance, called 
 also microcosmic salt, phosphorus salt, and fusible flux, is of 
 very general application, and as it dissolves most of the me- 
 
386 BLOWPIPE MANIPULATION : THE REAGENTS. 
 
 tallic oxides with great readiness, the colors produced in its 
 bead are, if possible, more brilliant and characteristic than 
 those made with borax. 
 
 Nitrate of Potassa, or saltpetre, is used to assist in the 
 oxidation of metals, as it yields up its oxygen very readily 
 when exposed to heat. 
 
 Bisulphate of Potassa in solution, is used to indicate lithia, 
 boracic acid, nitric acid, fluohydric acid, bromine and iodine ; 
 and also for the separation of baryta and strontia from other 
 earths and metallic oxides. 
 
 Vitrified Boracic Acid (glass of borax) is used to detect 
 the presence of phosphoric acid ; also small portions of copper 
 in alloys of lead. 
 
 Fluoride of Calcium (fluor spar), when mixed with bisul- 
 phate of potassa, serves to detect lithia and boracic acid. 
 Alone it is a test for gypsum. 
 
 Sulphate of Lime, or gypsum, in the form of plaster of 
 Paris, is sometimes used as a reagent with fluoride of calcium. 
 Nitrate of Cobalt. — This very valuable test is used in a 
 somewhat concentrated solution. 
 
 Alumina heated in the oxidating flames, after being moist- 
 ened by a drop or two of this solution, acquires a beautiful 
 pale blue color; magnesia a rose red tint, and zinc a bright 
 green. The solution is contained in a phial similar 
 Fig. 359. to the one represented in Fig. 359. The glass stop- 
 ple, tapering to a point, descends into the solution, 
 so that on withdrawing it, a small quantity adheres 
 to its extremity. Berzelius uses a cork stopple with 
 a platinum wire flattened out in the form of a spoon, 
 at the end which is immersed in the solution. The 
 phial may be of such a size as to be conveniently 
 received in the charcoal borer, page 381. Oxalate of 
 cobalt may be made to take its place, and as it is 
 used in powder, it is often of more convenient application. 
 
 Nitrate of Nickel in solution, or Oxalate of Nickel in pow- 
 der. The oxide of nickel gives a brown color to soda glass, 
 while potash, if melted with a substance containing it, ac- 
 quires a bluish purple color. A bottle similar to the one just 
 described may contain the solution of the nitrate. 
 
 Lead, very pure, and especially free from silver, is used in 
 cupellation. 
 
 Bone ashes are employed in cupelling metals containing 
 gold and silver, or some of the ores. The cupels are prepared 
 
BLOWPIPE MANIPULATION : THE REAGENTS. 387 
 
 by moistening a small quantity of the ashes, mixed with a 
 little soda salt to make it coherent, and by kneading the mass 
 in the palm of the left hand to the consistence of a stiiff paste. 
 A cylindrical hole made in a piece of charcoal is then filled 
 with the paste, and after the surface is smoothed with the 
 small agate pestle, a slight depression is made in the centre, 
 sufficiently large to hold the metal or mineral to be cupelled, 
 together with a small quantity of the proof lead. The cupel 
 is slowly dried by heating it carefully in a stove or over the 
 flame of a spirit lamp. The assay with the lead is then placed 
 on the cupel and submitted to the action of the exterior or 
 oxidating blowpipe flame. By the influence of this, the lead 
 is oxidized, and the fused litharge so formed, is absorbed by 
 the bone ashes, while the silver or gold is left behind in the 
 form of a brilliant globule ; which, before its complete purifi- 
 cation, exhibits the iridescence formerly described under 
 CuPELLATiON. Plattner describes a convenient instrument 
 for making the cupels. 
 
 Oxide of Copper is used for the purpose of detecting chlo- 
 rine. 
 
 Silicic Acid^ when melted into a fusible glass with soda, is 
 a test for sulphur or sulphuric acid. The assay must, how- 
 ever, not contain it. 
 
 Silver^ in the form of wire or foil, is made use of for ascer- 
 taining the presence of sulphuret of potassium, or any other 
 soluble sulphuret. 
 
 Tin Foil sometimes assists in the reduction of metallic 
 oxides, which are dissolved in a bead of one of the fluxes, and 
 by its use we sometimes get a more satisfactory result than is 
 obtained without it. For instance, when a small quantity of 
 copper is dissolved in a bead of borax, or of microcosmic salt, 
 and the glass is treated in the reducing flame, it sometimes be- 
 comes ruby red and opaque. But if the amount of copper is 
 so small that the reducing flame cannot produce this result, a 
 little tin added to the bead, and heated with it, makes the 
 proper appearance evident immediately upon its cooling. 
 
 Iron wire, which is generally that metal in its purest state, 
 precipitates some other metals from the difi^erent fluxes, or 
 separates therefrom, sulphur and the fixed acids. It is also 
 used to reduce phosphoric acid to phosphorus, which com- 
 bining with iron, forms a white brittle metallic globule, the 
 phosphuret of iron. 
 
 Besides the above mentioned tests, it is proper to have 
 
388 
 
 BLOWPIPE TABLE. 
 
 Formate of Soda, which, when anhydrous, is used to detect 
 arsenic in oxide of antimony. Test papers colored with lit- 
 mus, Brazil wood, and turmeric, are also convenient. 
 
 The substances mentioned in the foregoing list as reagents 
 are all of those which are essential to the completeness of the 
 blowpipe apparatus. While, however, occasions may arise 
 for the use of any or all of them, the great majority of exa- 
 minations with the blowpipe can be made with the aid of but 
 a few, and the possession of the first four or five upon our 
 list, with the fluid nitrate of cobalt and the metals referred 
 to, may be considered as quite enough to make the manipu- 
 lator competent to pursue ordinary investigations. 
 
 Blowpipe Table, — In the Laboratory all the instruments 
 essential to the expedition of blowpipe analysis are placed 
 within convenient reach of the operator. For this purpose 
 Gahn's table, which has drawers both in the side and front, 
 will be found very useful. The side drawers are divided into 
 many compartments, and are shown in Fig. 360, drawn out 
 from their usual position. The right hand drawer contains 
 
 Fig. 360. 
 
 the apparatus most frequently used, and the left that which is 
 less often required. The lamp, blowpipe, fuel, wick and other 
 necessaries of a rougher kind occupy those in front. 
 
 This table, although quite small, may be found to take up 
 too much room. Berzelius' case, which is much more porta- 
 ble, may then be substituted for it. It consists of a neat 
 
BLOWPIPE. — THE TRAVELING CASE. 889 
 
 mahogany case, exhibited in Fig. 361, which has a cover, and is 
 14 inches long and 9J inches wide. Each article is made to fit 
 closely in a corresponding cavity, so that it is kept firmly in 
 
 Fig. 361. 
 
 its place. It contains all the necessary apparatus for these 
 experiments, and scarcely occupies more space than an ordi- 
 nary portfolio. It is neatly put up by Kent, in New York, 
 with the apparatus and tests, after directions given by Ber- 
 zelius. 
 
 Traveling Case. — Although Berzelius' case occupies little 
 space, and can readily be introduced into a common trunk, 
 many mineralogists prefer having their blowpipe apparatus 
 enclosed in a still more compact form. The traveling case 
 is arranged very much in the same way as the large size of 
 surgical instrument cases, and consists of a piece of leather 
 forty inches or more in length, with sides capable of being 
 folded down upon the body, and long strips of the same 
 material tacked along its centre, so as to leave open spaces for 
 the insertion of the various pieces of apparatus. After these 
 latter have been deposited in place, the lateral folds are closed 
 upon them, and the whole is rolled up and tied with tape, or 
 brought together with a common strap and buckle. 
 
 It is advisable to place the largest instruments near that 
 end of the case which is first rolled up. When blowpipe 
 operations are in progress, the case can be unrolled and sus- 
 pended from a nail in a wall, so that free access can be had 
 to all its contents. 
 
 Besides the various parts of apparatus which we have been 
 describing, it is well that the operator should be provided with 
 a piece of sheet iron twelve inches or more in diameter, and 
 with a rim turned up around the margin. This may be placed 
 
890 
 
 BLOWPIPE : — THE TEST SERIES. 
 
 upon the table, under the lamp, and will serve to retain ignited 
 or other particles thrown off from the substance which is un- 
 der examination. A sheet of white paper placed over it will 
 enable the experimenter to discover with ease, minute par- 
 ticles which might otherwise be lost. 
 
 It will be well for the chemist to supply himself with a set 
 of chemically pure tests which may be kept in small stop- 
 pered vials. Such a series is very useful as affording the 
 means of comparing the behavior of a mineral with that of 
 the substance supposed to be an ingredient of it, and of thus 
 verifying results. Its possession, moreover, conduces to the 
 attainment of dexterity in manipulation, and of the knowledge 
 of the various reactions occurring under the blowpipe flame. 
 
 The set may consist of — 
 
 Alkalies 
 
 Baryta 
 
 Strontian 
 
 Lime 
 
 Magnesia 
 
 Alumina 
 
 Glucina 
 
 Yttria 
 
 Zirconia 
 
 Thorina 
 
 Silica 
 
 Acids of Arsenic 
 
 Vanadic acid 
 
 Molybdic acid 
 
 Tungstic acid 
 
 Oxide of chrome 
 
 Antimony and its oxides 
 
 Oxide of tellurium and telluric acid 
 
 Tantalic acid 
 
 Titanic acid 
 
 Oxides of uranium 
 
 Oxides of cerium 
 
 Oxide of lantanium 
 
 Oxide of didymium 
 
 Oxide of manganese 
 
 Oxide of zinc 
 
 Oxide of cadmium 
 
 Oxide of iron 
 
 Oxide of cobalt 
 
 Oxide of nickel 
 
 Bismuth and its oxide 
 
 Oxides of tin 
 
 Oxide of lead 
 
 Oxide of copper 
 
 Mercury 
 
 Oxide of silver 
 
 Sulphurets 
 
 Seleniurets 
 
 Arseniurets 
 
 Antimoniurets 
 
 Tellurets 
 
 Carburets 
 
 Sulphuric acid 
 
 Nitric acid 
 
 Chlorides 
 
 Bromides 
 
 Iodides 
 
 Fluorides 
 
 Phosphates 
 
 Cartonates 
 
 Boracic acid 
 
 Hydrates 
 
 Silicates 
 
 Salts of metallic acids 
 
 It has only come within our province to describe the im- 
 plements and adjuncts employed in blowpipe analyses, with 
 some few examples of the practical results obtained by means 
 of them. The excellent manual of Griffin, and the works 
 upon the subject by Berzelius and Plattner, contain most 
 complete accounts of this branch of manipulative chemistry, 
 and of the mode of conducting investigations by means of it. 
 
ANALYSIS BY POLARIZATION OF LIGHT. 
 
 891 
 
 CHAPTER XXVIII. 
 
 APPLICATION OF THE CIRCULAR POLARIZATION OF LIGHT TO 
 THE ANALYSIS OF SACCHARINE SUBSTANCES. 
 
 When a ray of common light passes through a doubly re- 
 fracting crystal, such as a rhomb of Iceland spar, it is sepa- 
 rated into two rays which have peculiar properties differing 
 from the original ray. These rays are found to possess similar 
 properties in planes at right angles to each other ; that is if 
 we suppose one ray to have certain properties in a horizontal 
 plane, the other ray will have similar in a vertical plane. 
 Each of these rays is said to be polarized, and to have its 
 plane of polarization at a right angle to that of the other. 
 
 If one of these rays be absorbed or prevented from passing 
 by any means, and the other whose plane of polarization we 
 will suppose to be horizontal, be allowed to pass through an- 
 other doubly refracting crystal, as Iceland spar, in certain 
 positions the polarized ray will be again doubly refracted, 
 and we shall see two images of the object from which the 
 light comes. But if we turn the second crystal in such a posi- 
 tion that its principal section^ that is the plane passing 
 through the axis A X, (which is the line 
 joining the obtuse summits of the rhomb,) 
 and perpendicular to one of its faces, is 
 vertical, that is at right angles to the 
 plane of polarization of the ray, only one 
 ray will pass through the crystal, the 
 other being stopped, and but one image 
 will be seen. If now we continue to turn 
 the second crystal, the remaining ray de- 
 creases in intensity, and the other begins 
 to reappear, and if we go on turning the 
 crystal through 90°, the first ray will disappear and the ray 
 which had formerly disappeared will be at its maximum in- 
 tensity. If we turn the crystal through another 90°, this ray 
 
 Fiff. 362. 
 
% 
 
 392 POLARIZER AND ANALYZER. 
 
 will again disappear and the other reappear. And so on 
 these changes alternate through every 90°, until finally we 
 come again to our original position, with the principal section 
 at right angles to the plane of polarization. 
 
 Now it is evident that if we should stop one of the two rays 
 into which the second crystal refracts the polarized ray, then 
 in certain positions we should have no light transmitted, and in 
 positions at right angles to these, we should have the greatest 
 intensity. 
 
 The first of these crystals of Iceland spar is called the 
 polarizing crystal, or polarizer, and the second the analyzer. 
 When we make use of two Nichols prisms, (which are rhombs 
 of Iceland spar so contrived as to transmit only one of the 
 doubly refracted rays,) one as the polarizer, and the other as 
 the analyzer, and the analyzer is turned until its principal 
 section is at right angles to the plane of polarization of the 
 polarized ray, no light passes. This position is called the 
 azimuth zero. When the analyzer is turned through 90° 
 from this position the polarized ray attains its greatest bright- 
 ness. Turning again 90°, the light disappears, and reappears 
 on turning through another 90°, and finally again disappears 
 in returning to the azimuth zero. 
 
 If when the polarizer and analyzer are in this position, a 
 
 piece of quartz which has been cut from a crystal at right 
 
 angles to its axis A X, or a solution of cane sugar 
 
 Fig. 363. \,Q placed intervening, so that the polarized light 
 
 ^ has to pass through them, the light immediately 
 
 R/K reappears, with a tone of color depending upon the 
 
 (j-V^ thickness of the section of quartz, or solution of 
 ° cane sugar. If we turn the analyzer in a direc- 
 
 sItt!^ tion from left to right, then if the original color 
 j[ was orange, for example, we shall find the pris- 
 matic colors succeeding each other in the order of 
 orange, yellow, green, blue, indigo, violet, red. When the 
 colors succeed each other in this order, the quartz and the 
 sugar are said to deviate or rotate the plane of polarization 
 to the right. When by turning the analyzer in the same 
 direction the colors succeed each other in inverse order, or 
 when by turning the analyzer from right to left the colors 
 succeed each other in the same order, the quartz and the 
 sugar are said to deviate the plane of polarization to the left. 
 In the former case the quartz and sugar are said to be right- 
 
CIRCULAR POLARIZATION. 
 
 393 
 
 handed^ in the latter left-handed. Crystallizable sugar de- 
 viates the plane of polarization always to the right, or is 
 right-handed, uncrjstallizable to the left or is left-handed. 
 Some specimens of quartz are found to deviate the plane of 
 polarization in one direction, and some in the opposite. 
 
 When the analyzer is not a Nichol's prism, but only an 
 ordinary doubly refracting prism, which allows both rays to 
 pass, and is in the position in which one of the rays into 
 which the polarized beam is refracted is stopped, then the 
 plate of quartz will cause it to re- 
 appear, and we shall have the two F^s- 364. 
 beams o and e. Fig. 364, colored but 
 not with the same tint, one comple- 
 mentary to the other. Two colors 
 are said to be complementary if they 
 produce white light when mixed. 
 
 These two colors vary as we rotate the analyzer, but in all 
 cases they are complementary. 
 
 If when the analyzer is at the azimuth zero, we substitute 
 for the simple plate of quartz, a plate composed oi right and left- 
 handed quartz, R and L, Fig. 365, the 
 line of separation of which is vertical, ^ig- 365. 
 
 then as they are of the same thickness, we 
 shall have the same appearance and co- 
 lors in the two rays, as we had in the 
 case of the simple plate of quartz of the 
 same thickness. For the two kinds of quartz being of the 
 same thickness, the one deviates the plane of polarization as 
 much to the right as the other to the left. Hence each one of 
 the rays, although of complementary colors, will be of the 
 same uniform color in itself. 
 
 But if the analyzer be turned each beam will be divided 
 into two different colors, ?, r, and Z, /, Fig. 366, and the colors 
 in one beam will be complementary to the colors in the other 
 beam. 
 
 If two plates of quartz of equal thickness, one right-handed, 
 
 Fig. 366. 
 
 Fig. 367. 
 
394 ventzke's apparatus. 
 
 the other left-handed, be made to overlap, Fig. 367, then the 
 effects of each separately, will be neutralized, and the plane 
 of polarization will not be deviated in either direction ; and 
 if the analyzer be at the azimuth zero, only one ray will pass, 
 as if the quartz had not been interposed. 
 
 Having now prefaced with the phenomena of polarized light 
 employed in chemical analysis, we shall describe the appa- 
 ratus of M. Ventzke, which is a modification of the original 
 apparatus of M. Biot, who first discovered the property of 
 the circular polarization of light possessed by sugars, and 
 other organic matters, and who founded on this discovery 
 his process of analyzing solutions of saccharine substances. 
 This apparatus was used by Prof. McCulloch in quite an ex- 
 tended series of analyses for the government of the United 
 States.* 
 
 A sketch of the apparatus is given in the annexed cut. The 
 
 Fig. 368. Fig. 369. 
 
 analyzer, which is a Nichol's prism, is placed in a brass socket 
 at A, another view of which is given at A (Fig. 369). This 
 socket is capable of a motion in the graduated disk and car- 
 ries an index I, which moves over the disk and measures the 
 number of degrees from the zero point, through which the 
 analyzer is moved. It is turned by means of a small disk F, 
 called the pinion disk, which carries a pinion wheel gearing 
 into a larger toothed wheel attached to the analyzer. 
 
 The polarizer, which is also a Nichol's prism, is fixed in a 
 brass socket at B. This socket has a toothed wheel which 
 
 * Senate Document 165, 2Sth Congress, 2cl Session. 
 
ventzke's apparatus. 
 
 395 
 
 gears into the threads of a perpetual screw, which is moved 
 by a milled head at h. The whole socket is capable of motion 
 in a groove, and of being fixed in any position by the binding 
 screw d. The tube which is to contain the solution of sugar 
 is shown at D. The peculiar construction of this tube will 
 be explained directly. A lamp is placed at E, which is re- 
 commended to be used instead of the sun, in order to insure 
 a uniform intensity of light. The whole instrument is mounted 
 on an iron foot. 
 
 The only adjustment necessary is to bring the principal 
 section of the analyzing prism at right angles to the plane of 
 polarization of the polarizer. This is done by putting the 
 index of the analyzer at zero, on the graduated arc, and then, 
 by means of the screw 6, turning the polarizer until we have 
 obtained the point of greatest darkness. This adjustment is 
 best made by sun light. This gives the azimuth zero. 
 
 It has already been mentioned, that crystallizable sugar 
 deviates the plane of polarization to the right, and uncrystal- 
 lizable to the left. Now, as the sugars, which in the majority 
 of cases the chemist is required to analyze, contain the two 
 kinds, it becomes necessary to appreciate the 
 effect of each kind separately in deviating the 
 plane of polarization. It has been found that 
 when hydrochloric or sulphuric acid is added to 
 
 a solution of pure cane sugar, which always 
 polarizes to the right, and the mixture is suf- 
 fered to stand for 10 or 12 hours, or is gently 
 heated, the cane sugar is converted into the 
 uncrystallizable, which deviates to the left, or 
 is left handed. Advantage is taken of this fact 
 in M. Biot's process of analysis. A solution is 
 made which contains 25 or 50 per cent, of the 
 sugar to be analyzed. This solution is then 
 filtered, and if it is much colored it is deco- 
 lorized by passing it through a tolerably coarse 
 bone black. It is then placed in a glass tube a, 
 Fig. 370, the ends of which are ground, and are 
 fitted with screws as shown in the figure. Over 
 the end of the tube is placed a round disk of 
 glass, 6, with parallel surfaces, and then the cap c is screwed 
 down over this so as to hold it tightly in its place. A hole is 
 
396 METHOD OF ANALYZING SUGARS. 
 
 pierced througli the cap at d, which allows the light to pass. 
 The other end of the tube is provided with a similar arrange- 
 ment. This tube having been filled with the solution is placed 
 in the apparatus in the position shown at D. The analyzer 
 is then turned to the right until the bluish violet ray begins 
 to appear. This color is chosen because it is one of the most 
 delicate, and its amplitude is small, and therefore is observed 
 with the greatest certainty. This angle is noted. Then one 
 part by volume of hydrochloric acid is added to nine parts by 
 volume of the solution, so that the original sugar solution 
 becomes -^^ of the acidulated solution. This is then suffered 
 to stand for 10 or 12 hours, or if gently heated to 154° Fahr., 
 is entirely converted into uncrystallizable sugar in 15 or 20 
 minutes. It is again placed in a tube, and the analyzer turned 
 to the left until the same bluish violet tint appears. This 
 angle is then noted. Previously to adding the acid, the dens- 
 ity of the solution is observed either by a good hydrometer, 
 or by weighing. 
 
 Calling the angle observed before acidulation the direct 
 angle, the angle observed after acidulation the inverted angle, 
 and the ratio of the original solution to the acidulated mix- 
 ture, which in the above example is y^^, the ratio of dilution; 
 then for convenience we may take the notation. 
 
 a = direct angle, 
 
 a" = inverted angle, 
 
 n = ratio of dilution = 0.9, 
 
 d = density of the solution, 
 
 e = per cent, of the original sugar contained in the 
 solution, which is either 25 or 50, 
 
 X = the per cent, of pure cane sugar in the original 
 sugar. 
 Knowing the first five quantities, we may calculate the last 
 by the following rule:* 
 
 * The formula which Mr. M'Culloch has given at p. 24 of his Second Report, 
 Senate Doc, No. 209, 29th Congress, 2d Session, is 
 
 153.7G ned 
 in which 
 
 1 _L // fi'f 
 
 — — — a' in which a' =z n a, and r" = — , 
 
 1.38 a' 
 
 the same notation as given above. 
 
DECOLORIZATION OF COLORED SOLUTIONS. 397 
 
 Multiply a by w, with the product thus obtained, as a 
 divisor, divide a" : add 1 to the quotient, and multiply by the 
 product of a and n ; divide the product thus obtained by 1.38: 
 divide the quotient by 153.76 multiplied by ti, by e and by x\ 
 the quotient will give the value of x, or the per cent, of pure 
 crystallizable cane sugar, contained in the original sugar. 
 
 In analyzing molasses the same process is followed. The 
 only difficulty which occurs is the decolorization of the solu- 
 tion; which maybe done by repeatedly filtering through tubes 
 filled with coarse bone black. A glass tube of J or f inch 
 interior diameter, and about 2 or 3 feet long, is taken, which 
 is narrowed at one end by the lamp and blowpipe; a loose 
 plug of paper is then put in the tube near this end, and the 
 tube is filled with coarse bone black. It is recommended by 
 M. Clerget not to collect the first part of the filtrate, as the 
 bone black absorbs some sugar as well as coloring matter, and 
 thus alters the per cent, of the solution. He recommends 
 that a volume of the solution about equal to that of the bone 
 black should be lost. The liquor, if not sufficiently decolor- 
 ized by the first filtration, may be passed through the same 
 black again. 
 
 Other processes may be employed which are known to 
 chemists, such as precipitating the extractive and coloring 
 matters by the subacetate of lead. In this case the solution 
 of the subacetate should be used as pure water, in making the 
 original solution. In defecating cane juice M. Clerget pro- 
 ceeds as follows: He prepares a solution of isinglass (fish- 
 glue) by macerating 5 or 6 grammes of it in 250 grammes of 
 cold water during 3 hours. He thus obtains a paste, which 
 is sifted or strained through a piece of coarse linen, and mixed 
 with 100 grammes of white wine or alcohol diluted with water. 
 Thus is obtained a gelatinous mass which may be diluted 
 with water until its volume is 1 litre (61 cubic inches). This 
 will keep in a corked bottle from 15 to 20 days, according to 
 the temperature. It should not be used when it becomes very 
 sour. If a small quantity of this be added to cane juice, or 
 any solution of sugar and mixed with it and then the same 
 volume of alcohol be added, the whole is coagulated, and the 
 solution is left perfectly clarified. The dilution of the solu- 
 tion which thus takes place must be taken into account in the 
 calculation of the per cent, of sugar dissolved. It may be 
 
398 soleil's saccharimeter. 
 
 compensated by increasing the length of the tube in the same 
 ratio. 
 
 In the October number of the Bulletin de la Societe d' en- 
 couragement pour V Industrie JSfationale, 1846, M. Soleil, the 
 celebrated optician of Paris, has described a nouveau sac- 
 charimetre of his invention, which is a great improvement over 
 the instrument which has been described, enabling the mea- 
 surements to be made with great precision. The instrument 
 is represented in the cut, Fig. 371. 
 
 The polarizer is placed at d, which is either a Nichol's 
 prisfn, or an ordinary doubly refracting prism. The ana- 
 lyzer is at a, which is a doubly refracting prism, which sepa- 
 rates the polarized beam into two, and in certain positions, 
 allows only one to pass. Immediately behind the polarizer at 
 e, two pieces of quartz of equal thicknesses, one right-handed, 
 the other left-handed, are placed, so that the line of separa- 
 tion is vertical, and in the middle of the field of view, so that 
 one acts on one-half the beam, the other on the other half. 
 Now, the analyzer being at the azimuth zero, from what has 
 been said, the same tone of color will be produced by each, 
 because they rotate the plane of polarization equally and in 
 opposite directions. Hence, although the two beams into 
 which the analyzer will separate the polarized light will be of 
 complementary colors, yet the color of each beam will be 
 uniform throughout. Now when the sugar solution is placed 
 at 71, if it is crystallizable sugar it will be like increasing the 
 thickness of the right-handed, and diminishing that of the 
 left-handed quartz ; if uncrystallizable, like increasing the 
 thickness of the left-handed and diminishing that of the right- 
 handed quartz. Hence, in either case the plane of polariza- 
 tion will be rotated more in one way than in the opposite, 
 and the amount of this rotation will depend upon the number 
 of particles of sugar, that is upon the per cent, of the solution, 
 and the length of the tube; and, therefore, each of the two 
 beams will be no longer of the same uniform tint, but one-half 
 of one beam will be of one color and the other half of the 
 other color, and the other beam will also have two colors 
 complementary to those of the first. 
 
 In order to measure the degree to which the plane of polar- 
 ization is rotated in either direction, M. Soleil ascertains the 
 thickness of the quartz of either kind, which is necessary to 
 compensate the effect of the sugar that is to render each beam 
 
SOLEIL S SACCHARIMETER. 
 
 399 
 
 v<^ 
 
400 
 
 SOLEIL'S SACCHAIIIMETER. 
 
 of a uniform tone of color. This is accomplished by his com- 
 pensator, which part of the apparatus is placed at c. 
 
 Now the effect of the sugar in deviating the plane of 
 polarization depends upon its purity and upon the strength 
 of the solution ; therefore, in order to compensate the effect 
 of the sugar in every case, it would be necessary to have a 
 number of pieces of quartz of various thicknesses, and of 
 contrary effect to the sugar, in deviating the plane of polari- 
 zation. This would be inconvenient, and M. Soleil overcomes 
 
 Fig. 372. 
 
 the difficulty in his compensator. Immediately before the sugar 
 solution, and near c, is placed a piece of quartz, which rotates 
 the plane of polarization to the right. At c there are two 
 pieces of left-handed quartz, cut as shown in Fig. 372. Now 
 
 Fig. 373. 
 
, soleil's saccharimeter. 401 
 
 when these two pieces a and h are in the position shown in the 
 figure, they have together the same thickness as R, and being 
 of an opposite kind to R, of course they neutralize its effect. 
 But when they are in the position shown at c? c? (Fig. 373), then 
 their thickness in the direction of the ray I I, is less than the 
 thickness of R^ and, therefore, the effect of R will predominate, 
 and it will compensate for a left-handed (uncrystallizahle) 
 sugar. When, however, the pieces are in the position shown 
 at e and /, then the thickness through ^ ? is greater than that 
 of R, and their deviation will predominate, and will compensate 
 for a right-handed (crystallizable) sugar. 
 
 These two pieces are mounted upon a small rack work into 
 which gears a pinion, which moves them in opposite direc- 
 tions. The pinion is turned by a milled head at b. These 
 two pieces have likewise attached to them two scales, which 
 are represented at c d . The smaller scale serves as a vernier, 
 10 of whose divisions correspond to 9 on the larger scale. 
 They are each graduated in opposite directions from a com- 
 mon zero point, and the extremities of both scale and vernier 
 are marked D, droits right, and G, gauche, left. When the 
 zero points coincide, the two pieces are in the position shown 
 at a and 6, and have the same thickness taken together, as R. 
 
 Each division of the large scale counts 10, and each of the 
 small scale 1. Thus if the zero point of the vernier was be- 
 tween 4 and 5 on the large scale, very near 5, we glance 
 along the vernier, until we find a division which coincides 
 with a division on the large scale. If this division is 9, then 
 the instrument gives the reading 40 on this large scale, and 
 9 on the vernier, or 49. 
 
 A lens is placed at g, which is to be so adjusted as to see 
 clearly the vertical division line of the two quartz placed at e. 
 This adjustment should be made while the tube u is full of 
 water. A spiral spring is placed at q to press against the 
 tube w, and keep it in its place. The whole instrument is 
 mounted on a pillar and foot. 
 
 Now supposing the lens at g adjusted so as clearly to see 
 the line of separation of the two pieces of quartz at e, and the 
 scale and vernier adjusted to their common zero point, the 
 only remaining adjustment is that of the analyzer to the 
 azimuth zero, which may be done by rotating it in its socket 
 until one of the images of the aperture at o has a uniform 
 violet color. When this is done, the analyzer is fixed firmly 
 in its place by means of the binding screw p. 
 
402 clekget's method. 
 
 In this apparatus a tube of the solution is used as in the 
 former case, and in order to determine the amount to which 
 it deviates the plane of polarization, the button at h is turned 
 in whatever direction tends to produce a uniform violet color 
 in the colored ray which was uniformly violet before the solu- 
 tion was placed in the apparatus. Then the direction in 
 which the vernier has moved will determine the kind of de- 
 viation : if towards D the plane of polarization is rotated 
 towards the right ; if towards G, to the left. 
 
 Analyses may be made in precisely the same way, and 
 calculated by the same formula with the exception of the 
 numerical factor 153.76, which will have to be determined 
 anew, as it depends on the instrument. 
 
 M. Clerget has given a table which supersedes the neces- 
 sity of calculation.* His process of analysis is as follows : — 
 Having made a solution containing 16.471 per cent, of pure 
 dry cane sugar, and placed it in a tube 20 centimetres 
 (7.8 inches) long, he found that it deviated the plane of po- 
 larization to the right 100°. Now if we were analyzing a 
 sugar known not to contain any left polarizing substance, 
 and we should find that it deviated the plane of polarization 
 80° to the right, then by stating the proportion : 
 
 100 : 16.471 : : 80 : X = 13.177. 
 
 Now dividing 13.177 by 16.471, we get the per cent, 
 of pure cane sugar in the original sugar. If, instead of 
 making this calculation, we refer to the table at the end of 
 this article, and look down the column A to the number 80, 
 the number in column B on the same horizontal line, is the 
 number of grammes and centigrammes contained in a litre 
 of the solution. The solution is supposed to be observed 
 through a tube of a constant length, 20 centimetres. 
 
 As the sugars to be analyzed generally contain left polariz- 
 ing sugar, it is necessary to take into consideration the effect 
 of this substance. A solution of the sugar or molasses is 
 made of the normal per cent. 16.471, and decolorized and 
 clarified according to the methods described. A tube 20 cen- 
 timetres long of the solution is then placed in the instrument 
 and the direct deviation noted. Ten volumes of the solution are 
 then added to one volume of concentrated hydrochloric acid, 
 
 * Bulletin cle la Societe d'encourageraent pour I'lndustrie Nationale, Oct. 184G. 
 
clerget's method. 
 
 403 
 
 and then put into a convenient vessel (a matras is best adapted 
 to this purpose), and the whole placed in a water bath and 
 brought up to the temperature 68° cent. (154° Fahr.). The 
 heat is so regulated as to require about fifteen minutes to 
 bring it to this temperature. It is then placed in a vessel of 
 cold water, in order to bring it to the temperature of the sur- 
 rounding air, and afterwards in a tube, represented in Fig. 
 374, adapted with a thermometer, so as to take the tempe- 
 
 Fig. 374. 
 
 rature of the liquor at the time the inverted angle is observed 
 in the polarizing instrument ; M. Clerget having found that 
 the temperature, at which the observation is made, has a great 
 influence on the deviation of the plane of polarization. Hav- 
 ing increased this last number by y^oth in order to compensate 
 for the dilution by the acid, it is added to the direct deviation, 
 and then entering the table, at the temperature at which the 
 inverted deviation was noted, we find the number nearest to 
 the sum, and the number in the column A on the same hori- 
 zontal line, will give the per cent, of pure sugar. 
 
 In the case, where the deviation before the acidulation and 
 after, takes place in the same direction, which may happen if 
 the crystallizable sugar is mixed with a large quantity of un- 
 crystallizable, then the difi'erence instead of the sum of the 
 deviations is to be taken. 
 
 Examples. — Suppose a liquor before acidulation gives 
 
 a direct deviation of 75° 
 
 and after acidulation, an inverted deviation at the tem- 
 perature of 15° cent. 20° 
 
 Sum 
 
 95° 
 
404 clerget's method. 
 
 Entering the table at the column of 15° centigrade, we 
 find 95.5 corresponds to 70 per cent, of cane sugar. 
 
 Again, suppose before acidulation the direct deviation 
 is - - - - - . . . - 80° 
 
 and after at 20° cent, the direct deviation is - - 26° 
 
 Difference ----- 54° 
 In the column 20° cent., 53.6 gives 40 per cent, cane sugar. 
 
 Those who wish to understand fully the application of the 
 phenomena of circular polarization to chemical analysis, are 
 referred to the memoirs of M. Biot in xiii. xiv. xv. vols, 
 of the Memoir es de VAcadSmie; to Professor McCuUoch's 
 Keport, Senate Documents, No. 165, 28th Congress, second 
 session, or the Scientific Memoirs, vol. iv. p. 292, which con- 
 tains a translation of some of M. Biot's papers. 
 
ANALYTICAL TABLES. 
 
 405 
 
 •paq 
 
 
 iwco^wor^QOC5 0»-ic>ieoTfiotor»aoo5p-- 
 
 5lS»(NOJO»^C<O»Sc0?5ft 
 
 r-i(?^co»rad^^05d — WTJ;u:>»xo50--co^^d^^grjc;o^c^rrd^>^aoo5-J 
 i-;5>Jciodt>^cJs»-^o»'^oda6c5d-iM'^irji>^aJoio"5Jc^-rf5rr^gQo5--< 
 
 eo«eoi'?»ioce^-^(C{ 
 
 I « «p 0> !?» lO OD ' 
 
 I t^ O CO U5 CD rH • 
 
 c50030<if5ao--T}«i>.oeo®osoJOGOi-"'S<tN.o«i<oocJ»ccx)r-iTft^o« ;d " 
 
 (r5«oiO»ioQ0 — Trt^.ocst^oeococswwco-N'^t^oeocoaxNWQOr-i'^oD 
 
 CO«C5CO'»OC^>0(JDT-lir5QO»-l><3'00«t^OCCOC>'r»OOC^lOCOr-'S'aD^ 
 
 co«q = wooiiT^cqc50<«OGno}icQq.-.Tj<oD^rt'f^q'^r^owcqc(Xi:£050» 
 
 w^ococoojooc5'?Joqo)ioo!NioaDCJ«5aD^iooD,-irj'ao,-^T)<r^^-.3< 
 rH (TJ TT « d t^ d d --^' « ■* w ^-: as d --< c4 ccVt cp !>-■ 03 d ^ ej Tji lo r>; f/' ^ 
 
 rH(7j■^odGddd<^j«"5l<d^»'aDd^^^wod^^ddT-^05■^u';^^c7Jd1-<*» 
 
 T4c^Ttiodcf5ddoiMTj<di>^xd-^?i'^iodx'ddoiMTt«>t>^aDd^c>j 
 
 r^^^o6Qddd^«;52ii2S5i§J^SSSSi????^^^^^^^ 
 
 «t^O'^t^T-c-<9<Q0.-<-«<QD — lCCDOJin050J«505W005CCl»OSOI^OCOt^O 
 ^^^«dc«ddCJC2^dj^xd-g^^^d00dd^g5^dc;:dd^« 
 
 C? t^ S TJ< i^ , 
 
 iau,-iioxc^iociOjfflC5cooo«r^ OTt^ — ■ 
 
 i-(W'S«i0»Q0C5O!NC3-*Ot^C0O--'5» 
 
 ,HrH-.rHT-l^i-*(M(NC<'MOJ(?J(M5»C0Cn« 
 
 lo to r^ C5 o ^ ( 
 
 
 iTl<QO(NiOOiC}COOCOe^O'<S<C 
 
 'odoDddfNW'stiradoidT 
 
 lOD (NO 
 
 
 I— ■^ or w o 
 
 « C5 '^ •^ •* 
 
 
 I — «5Ji5 o*iN 
 
 ant-' 
 t< -r 
 
 o Tj; 00 -- in X 
 
 OJ O S5 W f^ 
 
 
 53 c^<Mi 
 
 ) -^ «5 « W -.C O ■ 
 
 ■ ^»cos(McrOTj't>.-j»ncsojir> 
 
 3? 55; 
 
 ! 5» « C>1 
 
 oi q q ■<? t^ r^ 
 
 »o oi woo 
 
 • — mx 
 
 
 ^ f<; 1— iq O C? 1 
 
 o — c? '^ Q t>. ; 
 
 CO CO CO CO rt CO ( 
 
 • (MIOC5 
 
 ^. *^ ". 
 
 (NiNCJ 
 
 in X ?j o q 
 
 CO CO CO CO ^ 
 
 )c*«£O3eot^^>nc5Coi>'rtinQ0 
 
 woo 
 
 Tfxoioo'ri^ — « 
 
 oi CO i^ »- in 
 
406 
 
 ANALYTICAL TABLES. 
 
 
 ;i^^8^^8SS^^S538S?i;S!^2S^S 
 
 «StC>«COO<O<0tO<Dt^t''i^l>'t^l>"'JUUJQ0aDC)000CiC5C3OJC50>OOOC< 
 
 lOO i-H-NCO- 
 
 iu5U3ihiniO«5W>0«0>Oi 
 
 
 1 55 »o Ss «3 W SS I 
 
 !»oaqqc«;qaD-;-<s;<eqi7JTi;i>.o©» 
 
 .qwiooL — r;qq 
 i j>^ 00 C5 c; oi rj 'T o I 
 
 I QL; q « q OD 1-; ■o; i 
 ' r)< to t^ 00 C5 — ' cJ ^ 
 -O ;C CO CD «5 t^ t^ i 
 
 ; C-. ■7^1 iq !>; q CO iq 
 
 . 1^ S l^ 4^ qB 00 00 
 
 — « q q T< rr i 
 
 CJ W "er IC t^ od < 
 
 . OJ in t>; ; 
 — ' ci CO I 
 
 ICO coco < 
 
 I « in oc o C5 CO Oi 
 
 (N COT CO t^ 00 
 
 q c^ in GD q CO q 
 Ti<io<n wmo in 
 
 «§« 
 
 T <^ C I 
 CO CO CO < 
 
 iTrr»qi?*inoor^Trcoq(N 
 
 lO — coTTinccaooisi-ieo 
 
 .-I Tf t^ o c» in 00 
 d -i ffi Tf in CO t>^ 
 ' o in in w in in o 
 
 re^^'cTw inooq' 
 i d — oi T in CO IX 
 ' >n in in in in i?5 m 
 
 r- T t>; q W I 
 
 Ci d .-^ CO TT I 
 
 coco ( 
 cToj in ( 
 
 CO CO O ! 
 
 ■ in 1^ 00 o; o WPS 
 • t>- 1>. t>. <^ cx) XI 00 
 
 — T *>• C5 C* in QD 
 
 t^ ct5 ai d Tt ri -^ 
 
 y2 CO CO t^ »^ t^ i^ 
 
 -^ "fl; t^ q PS CO 00 
 co' <>^ OD d ,-.■ CJ TO 
 
 i>. *^ t» 00 X 00 QU 
 
 i in X f- rf !>. q CO < 
 
 ' in in «5 S in in in I 
 
 ■ocococ5(Ninx — 
 'cor-^ard^wcoiri 
 icctocO!or»r«t^t>. 
 
 TT i-'^ o n (O Oi ci 
 CO r^ c> d -H c*^ 
 
 t^ t^ i^ 00 GO UU 00 
 
 oi r»inoo>-i" 
 
 't^ceococsojinQo--' 
 
 > d ci CO Tp in t^ oi d »H rj CO in co' K 00 d -H oj T in 
 
 • inininininininincococococoocot^-f^t^-t^t^ 
 
 t>:qcoqqoiin 
 t^ ri r- 00 00 CD 00 
 
 — «a;t>;qeoqqcjinoD-^Tt>; 
 
 ■ § S W in 35 in in 
 
 eoTini^c 
 
 d r^ < 
 -OCO! 
 
 IgSgl 
 
 > CO t^ t^ t^ 1^ i^ 
 
 c CO CO o SM in 00 
 
 ,^ Tj> t>. q CO q q < 
 1 »H ■?! CO in CO j>^ x < 
 ' in in in in in in in ( 
 
 1 q (TJ in '^ 
 
 i & CO o c 
 
 idoicoTCD 
 ^ t>. t>. t>. <>. f» 
 
 eoqq c*»nooTH 
 
 ;qqcoqqwinq?jin> 
 ^cod-^'Ncoincor^dd' 
 'TTinininminininmS' 
 
 ; q CO CO q CO 
 
 i — ^ OJ COrp CO 
 
 ' t^ t^ r^ i^ j^ 
 
 CO o c^ in 00 s* in 
 *>; c/J d — ■ w T lo 
 
 t^ <> a; 00 00 00 uu 
 
 COT! 
 
 ) 00 W I 
 
 Ji-Too rHTt>.qTr^.q 
 
 iiniQininincoococoS 
 
 cococ 
 t^od d 
 
 COCOi^ 
 
 CO CO Ci OJ CO 
 
 .— 5* CO in d 
 t>. t>. j>. {^ 1- 
 
 oi 50 in 00 o» in 00 
 
 qeo 
 
 !>; q c^ q q ^o q 
 ^ CO T in J-^ 00 d 
 in in in in in in in 
 
 C3 CO 
 
 d 5* 
 
 coo 
 
 -.o C-. ^ 
 eoTco 
 
 » CO CO 
 
 CO c; SM 1 
 
 7* wi J, ,-1 in J- 
 
 cv in q ?j lo 
 
 i in d (■» c» d — . . ^ 
 iTj>TrTTininin>n 
 
 w. w in wi 
 •r-COTig 
 
 CO in j^ 
 t>^ uJ d 
 
 in in in 
 
 J- <r< m 00 50 in 
 
 CO CO CO ! 
 
 GO — inx ^ 
 -^coTirir^^ 
 t>. i^ t^ *^ t^ 
 
 in aq —_ in JO — T 
 orj d -^ oi CO in d 
 
 t>. b» 00 JO ou ou aj 
 
 ii§Tj<TTpi5>hu5ini?5i 
 
 I Tt in CO t 
 
 1 CO CO CO t 
 
 . -H T 00 — T 
 
 i 50 CO "T d <^ 
 <» t^ t^ t^ i^ 
 
 00 — ^r 00 -• ^" 00 
 
 on d -I 50 >* in d 
 
 t>. uu CD JO 00 00 00 
 
 iqqcoqqrrqqcoqq 
 'TinihininininincoSco 
 
 I in l^ X CS rH 5'J 
 
 Wm m 
 
 ajc^in< 
 
 in o CO c 
 
 eo/^s 
 T in «>■■ 
 
 coco o 
 
 >»!r int>^ 
 
 ; CO CO CO 
 
 C0<^ C 
 
 ood^ 
 
 CO COt^" 
 
 ■O- t^ O TP t^ 
 
 50C0«5dN: 
 !>. t>. !>. i'. i^ 
 
 coc3fr< 
 
 _ TJ- t^ r- T 00 r^ 
 
 R d — eoTint^^ 
 
 ■^ X 00 JO 00 OU 00 
 
 CO <^ » T «>• ^ ^' 
 
 'S2s;^£ 
 
 iinininininScocococo< 
 
 I Jt cj in 
 • ooo .-i 
 1 CO t>. t- 
 
 q jviqqeo 
 50 T iri d orj 
 j^ i^ 1^ j>. t^ 
 
 CO C CO t^ O T t^ 
 
 I—, tq 
 I d --^ 
 
 'inm 
 
 JO i IQ C-. , 
 
 COT ind ( 
 in in in in ' 
 
 iSco 
 
 -rf in 00 ( 
 
 1 CO i>- t>- ( 
 
 COt^CiO — « 
 
 I q CO q q -» !>; — 
 
 . t- 00 00 JO JO S 00 
 
 1 5^ffl ! 
 
 ; q •>r JO . 
 > in in in I 
 
 . in X CO : 
 
 ; X d -^ ; 
 I in in CO c 
 
 icoqq- 
 > in d 00 ( 
 
 I CO CO CO c 
 
 ©coco 
 
 O TO) — 
 
 50 q q CO t>; -: 
 
 inoininin®S«5cocD 
 
 inoi 50 
 
 ' d tx 
 
 CO c 
 
 CO ceo 
 
 d-^ 50 
 CO<^i> 
 
 >i t- J^ t^ t- 
 
 t^^rp XCO 
 
 CO ind t>^d 
 
 J>. !>. t^ !>. t^ 
 
 in C5 CO CO c Tp i~.~ 
 
 Tp rp T T o m 
 
 rr JL; 50 in 
 
 Ss in >n in 
 
 C CO CO t 
 
 x' d — c 
 
 in CO CO < 
 
 ' a:- — in 
 ! in i>^ i' 
 
 ) *^coco 
 
 Oi 50CO 
 d — 50 
 CO t^t^ 
 
 q CO t>; — in 
 rp in d 00 d 
 i^ *^ t^ 1^ i^ 
 
 00 50 q q CO !>; q 
 
 in CO 00 T c 
 
 q ^-J c 
 d 50 « 
 in in I 
 
 ; "^ '^. ^ ■ 
 
 I in S CO : 
 
 : O TP 1^ . 
 i ^ J^ X I 
 
 I 50 as o T 1^ 
 It in i^ odd 
 
 .!>.<>■ t^ t^ t>. 
 
 I in in in in in 
 
 CO t» — 1 
 
 ' d 5J( 
 
 coco ! 
 
 • inojco t^O" 
 
 I rp in {>• 'X C 1 
 . i^ t^ t^ t^ 00 I 
 
 t-i in c: 50 in o T 
 
 X 50COO5COt^ 
 
 STX 50 
 
 « ujinin 
 
 in ocoi 
 dd50( 
 in CO CO! 
 
 ; in q 50 ( 
 
 : CO coco i 
 
 I X 5J CO = to 
 
 I T d *■- d d 
 
 if* <>.<>■ t>. 00 
 
 t>; — in q 50 q q 
 
 00 X SJ (X JO X o 
 
 I €^ '- = • 
 iTTin> 
 
 50 q q T : 
 
 I in in in iri I 
 
 >COCOCOOCOCCCCf»t* 
 
ANALYTICAL TABLES. 
 
 407 
 
 'opq 
 
 
 «5aqo«waqT-^woo5»-t■^^*oc^«o^». pcowaDOC5cpo5i-<'*oo5WTj;i>.< 
 
 S§S^ 
 
 i^S^o* — ^ 
 
 g8S5iSg§S§§SS&g2::2S222i:22S?;?J^ 
 
 
 't^OOl^ 00, 
 
 ' " ' ■> CD 05 O C 
 
 lOOlOC 
 
 »qxoe3oci'r«Trr«o«ooo^-iti<i^oo»ioa)^'«>cosiC<>oQDoco!005'?*'9< 
 
 
 
 
 «5jq— ;eo«C3i^Oja 
 
 ^ C5 » Ci 0» LT X r^ 'S" t>- _ Sy lO ^ r-; TT t^ 
 
 ^SIwS 
 
 oqTHrt<t>.oeo«oo30J«5ao»-iTj<jt^occicoo5«icx^rri^scc-.cci5\i 
 
 
 
 
 
 C5 C^ l« Cl 
 
 ^rj«QD^^t^OTJ>l>.pS^«>0«OS5WcOO;OJ«3X'7l«Oa0^^aO — 
 >JOQDXIC5CiOi050505C5^0S=_Oi = — — r-(-^ — — «OJW(MS« 
 
 i§li 
 
 <g; j^ -, rr i^ _ rr i>. ^ ,3- l>. ;^ .0 1,. ^ ,;> O O CO « w. CC. » 33 'M O iT^ O* vfS 
 
 XX05C5C5S503050iS5 0SCOS=-^-^-H-^-^rt-^ — ■MWMC^ 
 
 C3 3^ O vfc; 
 
 lo t>^ od oj 
 
 0» <N 5^ 5< 
 
 X r^ TJ< j^ _ TT ^ _ . 
 
 ua xocjcjo; 
 
 ■ r- TT t^ O -"T i-- ^ 
 
 (^ 3 ^ t^ O ! 
 
 iSoJcyco 
 
 • rj" j^ — lO J. 
 
 1 w 5>* CO ■ 
 
 
 X c* w cc 
 
 ;cB»-j«5QD-^ioxwi«Qoc^icosc^»no5Wp050^-qqco®C; copo 
 Joi^c^foirsdi>^oid»-Jco'3"u:>r»>-ci — '?ico»odt^ojd-jco^d 
 
 COO p eo 
 r^ x s -H 
 
 CO aid Oi a i 
 
 »J lO Ci -w o 
 
 Tji ffl j>; »■ 
 
 :? o — CO t^ w -^j" t^ = -^r 1^ r- -"T 
 d -- CO •^ m' *^ -o C3 — rj CO lo d 
 
 X T— lO X 
 
 cnScoco 
 
 I ■<j> X — lO JU C^ 1 
 
 1 CO -o ;= CO 
 j ^ S5 X oi 
 
 t>- O t <>• — rr X ^ «5 X W lO Oi 
 
 2 2J:tZ2ifi'S?3?iS55^ 
 
 
 •«* X — lO od; 
 
 i S3 coo p CO 
 
 ' X d — CO •» 
 
 
 
 i-^ TV CO vrj ! 
 03 03 03 03 ; 
 
 ■SiiiS 
 
 ^_ TT X -- lO 
 
 C3 03 & 03 03 
 ~^"35««0O5 
 
 d-ieo^ in 
 
 03 03 03 03 03 
 
 acoi 
 
 503; 
 CO^Oi 
 03 03 
 
 'SSS2: 
 
 >opco 
 
 icoSeo 
 
 iCOt^O"*^" — OX'N0 03eOI>.O^TQD 
 
 O 't t^ »-i lO 
 
 p :v p p 
 •r-' (t5 d -- 
 
 ^ — -iiiiH--?}?}! 
 
 ) — >o pco 
 IcocowS 
 
 t^ ^<oai 7i 
 
 <o o 
 
 5SSSS' 
 
 oo- 
 
 ■i2: 
 
 ' <-- — lO 03 CM O S TJ" t^ - >fj s: .M 
 
 ;2J^^22i2c5?Js5o3^?5^ 
 
 P P TT t^. 
 
 ^ CO CO CO 
 
 r^ vq X »J -i.. • 
 
 5&d3 03 03< 
 
 «»• CD (N «; d' 
 a»03ao>o 
 
 I <>. _ lo 03 CO 
 
 S82:: 
 
 S^ «5 p CO !>; — ^. J-. -^ - p .J i~: 
 
 co^ior-^ccdT-IjiTror-'ood 
 
 iSS^ 
 
 CO r^ -< u5 03 CO a: 
 
 ;S5SSS8S§: 
 
 :2J:2g=3S55^£;2J5 
 
 ;S^S 
 
 !>. —irtpCOl 
 Ob Ob Ca C6 Oa < 
 
 ' lo C3 n o o ■ 
 
 iO'^X— OC3C0<>. — "COSCOi^ 
 
 i. rr J. w 
 
408 
 
 ANALYTICAL TABLES. 
 
 
 ^|M 
 
 
 ^|<1 §§|||SS||g|2^^25^|52S|^gJ|S^S^?i§| 
 
 1 
 
 
 O 1 i^C5e<?«OQD^e«5«C5?<"»t-0'?<iOGC;0«ttCS«rpt>.050JOt^O«<»aD-^ 
 
 1 
 
 
 g 
 
 o 
 
 CO 
 
 t- ;; r: -^ X — TT t- o ■?! ir: 7. — TT :c cr. T< o a; o CO ts C5 -w* t^ o cc !C X' — -"s- 
 
 i= /■ ~ d — ?t rr i.~" (-' t" Cv' C: TJ r~ — 1.0 f^ x' S; — fj CO -f ®' »^ x' O -^ Ct CO lO O 
 
 c5T>?irocor-rccor-r'?:Tr'^-r-rrrrr'r-*o>oioiq55ioioO'0«ooo 
 
 
 o 
 
 CO 
 
 01 o / - 70 - zr. 0* uo /- - CO -.:: r. o» o x - co -.o cs o» .o x c= co «; c-. O'J o x = 
 
 o J. s rr -,c a c^ -^ *^ = r: ::: cr-. 7' o J. -: r: !c =5 c>» iq X -^ rr <>; q w lo JJ -: -r «>: 
 
 S 
 
 
 OJ o X - -^ i^ CO -i c: -. TT t^. q q q q o^ uo x - -r <- q q q q o< >q /. _ q 
 
 <5 
 
 ■ u i- =5 X «; ^. S) « J- - T .- = .-0 -i 5; c^ o J., r-. TT t- q « q q c^. o a ^ rr t- q 
 
 1 
 
 o 
 o 
 
 CM 
 
 C< o X — rr I- = 75 -.c C5 Oi o X <M >c X — IT t-: q q q q 0^ o /. - ^r <- q q q 
 
 
 t^ o CO :s 35 wo C5 c>< in X — T 1- o 00 « =: 00 «; C5 (M in X -^ •«' t-. — -^ «>; q q 
 
 
 w in X - rr X — rr 1^ = CO -^ = CO tt C-. oi in X ■?; iq X — r); t- - -"t 1-: q q q q 
 
 > 
 
 O 
 CJ 
 
 i- s CO -^ ~ CO a -. 01 -4; 05 TJ o X 0) m x — -q- x — t j^ o "V t^ o q cc o co o 
 
 < 
 
 ?, 
 w 
 
 (N in X ^ m X — in X - ■» t- — ^ j^ s •» t-_ q q !>. q q q q q q q q q q oi 
 
 
 o 
 
 i^ o CO f- = 00 •>= - q w q q q q q q q q q q q q q q q ~. ~>. ~. --. '». q ^. 
 
 5 
 
 o 
 
 (ji in ») c^ in X oiin x oi uo x o>* m x •?* m sr. o* c: c; o* 'O ci »i m o w o o o* m 
 
 o 
 
 CM 
 
 1- = CO t- = ■* *- = 's- '^ - -v^ - ''• ' -^ -^ c: - q X — q X (?j iq X 'N q q OJ 
 
 ^ 
 
 o , ^ lo X -M in OS cv) o 05 r? q q « q q r: t>; q 'i; t>: _ ^ f- -: t X ^ iq a ?> in x 
 
 2 1 igi^S§^^§^|^f|.^.3il^.l|-£-^S'lli|3iHi:S 
 
 > 
 
 o 1 CO = r; t- = ■* «- - '-'3 7- — « X -?! vn q -7* q q r; q _ cc t- q ^r <- — rr x -- o 
 
 2 1 g§i^ii5^^1rii5?§§i2Slsiilil§SSi:S 
 
 » 
 
 H 
 
 o 
 
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ELECTRICITY. 409 
 
 CHAPTER XXX. 
 
 ELECTRICITY. 
 
 Since the introduction and improvement of the many forms 
 of apparatus now in use for the production of electricity and 
 its kindred imponderables, it has become necessary for the 
 chemist to be well acquainted with their mode of manufacture 
 and employment. Many of the processes of the laboratory 
 are now performed or assisted by means of them, and a know- 
 ledge of their construction is important not only as being the 
 first step to an acquaintance with the principles concerned in 
 their action, but also as affording the power of excelling in 
 practical skill, and of preparing, extemporaneously, instru- 
 ments to take the place of the more expensive ones made in 
 the shops. 
 
 We propose accordingly to give an account of the mode of 
 operation of the various instruments used for the production 
 and detection of electricity, with directions for their proper 
 employment, and some of their most common applications to 
 the purposes of the experimenter and practical chemist, be- 
 ginning with the one which is in most common use. 
 
 Oylinder Electrical Machine. — The various parts of this 
 instrument are shown in Fig. 375. A, is a glass cylinder 
 which is made to revolve by the turning of a winch con- 
 nected by a crossed belt with the wheel and axle attached to 
 the two axes of the cylinder. These turn in the supports 
 seen at its sides. F, is the negative conductor supported by 
 a glass pillar, and having on the side, nearest to the cylinder, 
 the rubber or leather cushion which presses against its sides. 
 The cushion has attached to it the silk flap G, which extends 
 nearly over the upper part of the cylinder's circumference. 
 Below, a screw passing through two nuts, is so placed as to 
 increase or diminish the friction of the rubber upon the glass, 
 by making the distance of the movable pedestal upon which 
 the former stands, greater or less from the main support of 
 the machine. Upon the opposite side of the cylinder, is the 
 27 
 
 ki 
 
410 
 
 THE CYLINDER ELECTRICAL MACHINE. 
 
 positive or prime conductor C, being, like the other conductor, 
 a hollow cylinder of brass or other metal, also insulated and 
 
 Fig. 375. 
 
 provided with balls for the transference of the influence, but 
 having instead of a rubber, a collector E, provided with sharp 
 points or prongs which are almost in contact with the surface 
 of the cylinder. 
 
 The machine is often simplified by having the handle at- 
 tached directly to the axis of the cylinder, and by dispensing 
 with the screws and other parts of the arrangement in a way 
 to be hereafter described. As arranged in the figure, it is 
 made to develop electricity by turning the winch, which 
 causes the smaller wheel and the attached cylinder to revolve 
 with accelerated rapidity. By the friction of the glass upon 
 the rubber — covered with a metallic amalgam — the electricity 
 naturally present in the latter is supposed to be decomposed, 
 its positive element becoming attached to the glass and its 
 negative one to the cushion. The former, prevented from 
 escaping by the non-conducting silk, is carried around with the 
 glass, and — after a series of alterations by induction, of the 
 equilibrium of that portion of the fluid naturally present in 
 the conductor — finally by passing into it through the highly 
 conducting collector, fills it with positive or vitreous electri- 
 
THE CYLINDER ELECTRICAL MACHINE. 411 
 
 city, which can be drawn off from it into other conducting 
 bodies, either insensibly or in sparks. The negative conductor 
 while insulated, becomes in the same way negatively electrified, 
 and is capable of giving sparks to, or rather receiving them 
 from, other bodies oppositely influenced: but while uncon- 
 nected with the earth, it gives off to the cylinder but a small 
 amount of its positive component, and it soon returns to its 
 former state of equilibrium, from its negative electricity being 
 neutralized by the positive kind of the prime conductor, which 
 passes back over the surface of the cylinder, and which also 
 reaches it by other sources of imperfect conduction. 
 
 If much positive excitement is desired, the conductor to 
 which the rubber is attached, must be kept in connection with 
 the earth, or a conducting surface in contact with it, by a 
 metallic chain or wire. When, on the contrary, the intention 
 is to obtain negative electricity from its proper collector, 
 the prime conductor must be made to communicate with the 
 earth by the same means. 
 
 Not a little care is necessary in the construction and ar- 
 rangement of all the parts of the electrical machine. The 
 cylinder should be strong and well annealed, particularly at 
 the projections which are to be received into the caps forming 
 the centres of motion. Its sides should be as straight as pos- 
 sible, so as to be adapted uniformly to the rubber, and to 
 allow it to run truly upon its axis. Moisture should be care- 
 fully expelled from its interior, by a long-continued exposure 
 to a current of dry and warm air, and the lateral orifices 
 should be hermetically closed by cementation to the caps 
 which form the axes. Cylinders of the proper size and form 
 are sold in our glass-works and shops, but when one cannot 
 be obtained, a properly made glass jar or bottle, may be so 
 attached to a wooden or metallic axis — passing through its 
 mouth and through a hole in its concave bottom — as to make 
 a very good substitute. 
 
 The cushion, or rubber, consists of a pad made of buck- 
 skin or soft leather, stuffed with horse-hair or similar material, 
 and mounted upon a support which is in connection with the 
 negative conductor. In the greater number of cases, there 
 is no occasion for the presence of this latter part of the ma- 
 chine. When positive electricity alone is to be collected, the 
 rubber may be with propriety attached to a wooden support, 
 which is by any means made capable of being drawn towards, 
 
412 THE CYLINDER ELECTRICAL MACHINE. 
 
 or separated from, the cylinder. The flap attached to the 
 rubber is generally made of unoiled black silk, and it should 
 reach nearly to the extremities of the pointed collector, so 
 that its full effect may be produced, namely, the preventing 
 of the transmission of electricity into the air before it reaches 
 the prime conductor. 
 
 The exciting power of the rubber is much increased by 
 spreading upon its surface an amalgam^ mixed with unctuous 
 matter, to make it adherent. A mixture of the amalgam of 
 tin — scraped from the back of a mirror — with a little lard, 
 answers the purpose very well ; but the best kind, and that 
 in most common use, is made by adding to six parts of mer- 
 cury, previously heated in a crucible, a melted alloy of two 
 parts of zinc and one part of tin, and by rapidly stirring the 
 mixture until it is cold, when it can be readily reduced to 
 powder. Before applying it, the cushion is cleaned and 
 roughened by scraping, and is greased with a little lard or 
 tallow. Some of the amalgam is then intimately mixed in a 
 mortar with a quantity of unctuous matter suflficient to make 
 it of a pasty consistence, and enough of this is smeared upon 
 the surface of the rubber to give it a metallic appearance. 
 The cylinder is then to be turned rapidly while the cushion is 
 forcibly pressed upon it, and after the amalgamated surface 
 has been compressed and equalized by the friction, the super- 
 abundance of grease and metal is wiped off from the surface 
 of the cylinder and flap. The impregnation of the latter 
 with a small portion of the amalgam, and the presence upon 
 the surface of the former, of minute spots of it, are rather ad- 
 vantageous than otherwise. The mode in which the amalgam 
 assists in the production of electricity is not precisely known, 
 but it is supposed that its oxidation by friction and exposure 
 to air has something to do with it. The facts that amal- 
 gams of gold and other difficultly oxidable metals do not in- 
 crease the development of the power, and that an atmosphere 
 of carbonic acid surrounding the machine prevents it entirely, 
 seem to favor this belief. 
 
 The conductors of the two kinds of electrical influence are 
 generally of the form shown in the figure, and usually con- 
 sist of hollow cylinders of brass or tinned iron. They may 
 be turned out of wood and covered smoothly with tin foil, 
 which answers the same purpose, as it has been found that 
 the electricity, even when in a state of great tension, is con- 
 
THE PLATE ELECTRICAL MACHINE. 419 
 
 centrated chiefly in the surface. Small brass knobs or balls 
 are attached by thick wires to the sides and tops of the con- 
 ductors, for the purpose of drawing off sparks from the ma- 
 chine. In the absence of these, leaden bullets with wires 
 inserted, may very well be used. The conductors are sup- 
 ported upon glass pillars or tubes, which are coated with a 
 varnish of shell-lac. These, as well as the caps of the cylin- 
 der, are firmly inserted into their connections by means of 
 the cement described upon page 276. 
 
 The Plate Electrical Machine. — The power of this de- 
 scription of machine is believed to be much greater than that 
 of the kind in which the cylinder is used. The objection to 
 its employment has been the diiOficulty of insulating the cush- 
 ions, and consequently of obtaining negative electricity. It 
 has, therefore, been chiefly employed for class demonstrations. 
 Dr. Hare, in his Qompendium^ describes one which he has 
 successfully used, a long time, for the purpose of producing 
 both kinds of influence. The machine is represented in Figs. 
 376 and 377, and the following is the description : — 
 
 " The plate B (thirty-five inches in diameter) is supported, 
 as represented in the figure, upon an upright iron bar, about 
 an inch in diameter, covered by a very stout glass cylinder 
 A, four inches and a half in diameter, and sixteen inches in 
 height, open only at the base, through which the bar is intro- 
 duced, so as to form its axis. The summit of the bar is fur- 
 nished with a block of wood, turned to fit the cavity, formed 
 at the apex of the cylinder, and cemented therein. The ex- 
 ternal apex of the cylinder is cemented into a brass cap, 
 which carries the plate. The glass cylinder is liable to no 
 strain. It is only pressed where it is interposed between the 
 block of wood within, and the brass cap without. The remain- 
 ing portion of the cylinder bears only its own weight, while it 
 effectually insulates the plate from the iron axis. The brass 
 cap is surmounted by a screw and flange, by means of which, 
 a corresponding nut, and disks of mahogany, the plate is fast- 
 ened. A square table serves as a basis for the whole. The 
 iron axis, descending through the top of the table, is furnished 
 with a wooden wheel of about twenty inches in diameter D, 
 (Fig. 377,) and terminates below this wheel in a brass step S, 
 supported on the cross of wood, which ties the legs of the 
 table diagonally together. The wheel D, is grooved and 
 made to revolve by a band, which proceeds from around a 
 
414 
 
 THE PLATE ELECTRICAL MACHINE. 
 
 vertical wheel W, outside of the table. This external wheel 
 has two handles, by means either of one or both of which it 
 
 Fig. 376. 
 
 may be turned. It is supported on two strips of wood G G, 
 which, by appropriate screws (represented at S S, Fig. 377), 
 
 Fig. 377. 
 
THE PLATE ELECTRICAL MACHINE. 415 
 
 may be protruded, lengthwise, from cases, which confine them 
 from moving in any other direction. Consequently, the dis- 
 tance between the wheels may be varied at pleasure, and the 
 tension of the band adjusted. 
 
 "Nearly the same mode of insulation and support, which is 
 used for the plate, is used in the case of the conductors. 
 These consist, severally, of arched tubes of brass, of about an 
 inch and a quarter in diameter, which pass over the plate 
 from one side of it to the other, so as to be at right angles to, 
 and at a due distance from, each other. They are terminated 
 by brass balls and caps, which last are cemented on glass 
 cylinders C C C C, of the same dimensions, nearly, as that 
 which supports the plate. The glass cylinders are suspended 
 upon wooden axes, surmounted by plugs of cork, turned ac- 
 curately to fit the space which they occupy. The cylinders 
 are surrounded and secured below, by wooden rings screwed 
 to the table. In this way the conductors are efiectually in- 
 sulated, while the principal strain is borne by the wooden 
 axes. 
 
 " Collectors consist of hollow hemispheres of sheet brass, 
 within which several points proceed towards the plate from 
 their centres respectively, where they are attached to the 
 knobs K K K K. The hemispheres are intended to diminish 
 the injurious circulation of air. 
 
 " The cushions are included between springs, by which they 
 are made to press with an elastic force upon the surfaces of 
 the glass, the degree of the pressure being regulated by a 
 screw." 
 
 Electrical machines of whatever kind, act to the greatest 
 advantage in clear, cold and dry weather. A moist and warm 
 condition of the atmosphere is generally unfavorable to their 
 use, but various circumstances, — of which unknown meteoro- 
 logical influences are probably the chief — oppose the electric 
 excitement even in an apparently propitious state of the 
 weather. Care should be taken in such cases, whatever the 
 condition of the air, that the communication of certain parts 
 of the apparatus with the earth be as perfect as possible. 
 With this view, when either kind of excitement is required, 
 the conductor of the other kind may be connected by means 
 of a chain or wire with the water or gas pipes of a house, or 
 any other good conducting substances which penetrate the 
 moist earth. The cylinder, or plate, and the insulating parts 
 
416 THE LEYDEN JAB. 
 
 of the apparatus should be free from moisture or dust, which 
 might both conduct away electricity, and to ensure perfect 
 dryness of all parts of the machine, it should be placed before 
 a fire or upon a stove or sand bath, and be thoroughly rubbed 
 and dried with a piece of warm flannel, taking care that the 
 amount of heat applied be not great enough to melt the ce- 
 ment, which is employed to connect the various parts. 
 
 It is an indication that the machine works properly, if after 
 several revolutions of the cylinder or plate, the approach of a 
 metallic ball or of the knuckle to a part of the insulated con- 
 ductor, causes a vivid spark to dart with a crackling noise 
 from the latter to the former. The size of the spark and 
 loudness of the report are of course dependent in a measure 
 upon the magnitude and power of the machine. 
 
 The Leyden Jar. — This instrument, shown in Fig. 378, is 
 the one employed for the purpose of accumulat- 
 Fig. 378. ing electricity by induction, and is the agent 
 Q chiefly made use of for laboratory purposes. It 
 
 T usually consists of a wide-mouthed jar of thin 
 
 ^HpN, glass, coated with tin foil both upon the inner 
 
 ^u «» j and the outer side of the bottom and the lower 
 
 jLja two-thirds of the circumference. The stopper 
 JJSk is made of cork or dry wood, well varnished 
 IIB and cemented tightly in its place. Through its 
 
 |||H| centre, a wire or rod passes, which, either with 
 
 lil^B__ ^^ without a chain attached, is in close contact 
 MMKtK^ below with the inner lining of the jar, and 
 which terminates above in a smooth metallic 
 ball. That part of the glass which is not covered with tin 
 foil is usually painted over with a coating of shell-lac or com- 
 mon spirit varnish. The jar made use of in the laboratory, 
 need not ordinarily exceed a quart in capacity. The ball 
 upon the top of the rod should be at least an inch in dia- 
 meter, and the latter should be so firmly fixed in its place as 
 not to be dislodged from its connection with the stopper or 
 the bottom of the jar, by any change of position. 
 
 A common phial containing iron filings — into which is 
 plunged a wire which passes through the cork, and is inserted 
 into a bullet above — and coated outside with tin foil up to the 
 level of the metal within, makes a very efficient apparatus. 
 
 The Leyden Phial is charged by placing its ball in contact 
 with that conductor of the machine which contains the kind 
 
THE LEYDEN JAR. 417 
 
 of electricity which it is intended to accumulate in its inner 
 coating, while the outer metallic surface is in connection with 
 the earth. This is most conveniently performed by grasping 
 the jar in the hand, and presenting the knob to the conductor 
 during the continued turning of the winch. 
 
 The electricity often accumulates in the inner coating until 
 its tension becomes so great that the equilibrium of both coat- 
 ings is restored by a discharge taking place from one surface to 
 the other ; that amount which is in excess leaping over, as it 
 were, the intervening non-conducting surface of glass. When 
 one kind of electricity is collected in the interior, the opposite 
 sort is produced in the exterior coating, or — in accordance with 
 the theory which admits the existence of only one kind — 
 when it is in excess in the inside, it is deficient in the same 
 ratio upon the outside. The tendency is then always to re- 
 store that neutrality, or natural order of things in which the 
 influence is not made evident to the senses; but in a good 
 Leyden jar, the parts should be so arranged as to permit the 
 collection of a large amount of electricity before a sponta- 
 neous discharge takes place. If the jar, before becoming 
 highly charged, permits such an escape, it is usually an evi- 
 dence that there is a hole or crack in the glass, that the un- 
 covered surface has become a partly conducting one from the 
 presence upon it of moisture or dust, or finally that the outer 
 metallic coating extends up so far as to allow of the easy 
 passage of a spark to it from the rod or ball. The last con- 
 dition can be altered by lessening the height of the outer 
 covering of foil, taking care to reduce that which is within, 
 also to the same level. To expel moisture and dust, the vessel 
 should be warmed and wiped, as before directed for other parts 
 of the apparatus. 
 
 The retention for some time, of the charge, by the Leyden 
 jar is often a matter of great importance in the chemical 
 applications of electricity. A jar, of the capacity above men- 
 tioned, when dry, warm, and fully charged, should after a 
 lapse of ten minutes, give a spark at least half an inch in 
 length, to the ball of a discharging rod, the ball being one- 
 third of an inch in diameter. 
 
 The power of the jar is dependent on the amount of the 
 coated surface, and the thinness of the glass. 
 
 The Electrical Battery. — This is an arrangement by which 
 the metallic surfaces of the Leyden jar are greatly in- 
 
418 
 
 THE ELECTRICAL BATTERY. 
 
 creased in size, and by which the intensity of the shock and 
 discharge is multiplied to almost any extent desired. A 
 number of Ley den jars prepared in the usual manner, are 
 placed in a box which is lined with tin foil or other metallic 
 coating. The vessels are placed in close contact, or are made 
 to connect with each other externally, by the interposition of 
 metallic or coated partitions, and the inner coatings are made 
 to communicate by means of metallic rods or chains, connected 
 with the wires going from their interior. The whole is equi- 
 valent to a single large jar, and may be charged and dis- 
 charged with equal facility. Fig. 379. 
 
 Fig. 379. 
 
 The hook, seen in the front of the box which contains 
 the series, is attached to the metallic outer lining. 
 
 When the battery is to be used, it should be ascertained 
 that all the outside coatings are in proper connection with 
 each other, and that the inner surfaces communicate through 
 their appropriate mountings and wires, and that no wires, 
 threads, water, or other conducting substances extend in any 
 way from the inner to the outer parts of the apparatus. No 
 filamentous or pointed body, or projecting piece of metal, 
 should be allowed to remain very near the battery while it is in 
 operation. The battery is charged by connecting one of the 
 wires or knobs which are in contact with the inner coating of 
 the jars, by means of a chain or wire, with the prime or ne- 
 gative conductor of the electrical machine while it is in ope- 
 ration. It is both filled and discharged in the same way as 
 the Leyden jar, and all its operations are those of that vessel 
 upon a greater scale. 
 
 During the charging of a battery, a difi'usion of electricity 
 
THE DISCHARGER. 
 
 419 
 
 sometimes takes place over that part of the uncoated glass, 
 which is near the edge of the foil. This is not entirely re- 
 moved upon the discharge of the coated part, but afterwards 
 gradually returns to the coating and recharges the battery, 
 often to a considerable extent. Hence if after the discharge 
 of a battery, it be left for a few minutes with the two coatings 
 unconnected, it will, upon the application of the discharger, 
 give a considerable spark. This, which is the residual charge, 
 is discharged in the same way, when the Leyden jar is used. 
 
 The Discharger. — A discharge between the oppositely elec- 
 trified surfaces of the jar may be effected by bringing one 
 hand in contact with the external coating, and touching the 
 knob with a knuckle of the other. In this case the person 
 receives a shock in his arms, and if the surfaces are large or 
 well filled with electricity, he experiences a painful passage 
 of this shock through the shoulders and chest. A battery 
 ordinarily charged, should never be discharged in this way, as 
 serious and even fatal results might follow. 
 
 The instrument, shown in the figure, is called a discharger 
 and is used to complete the circuit between the opposite coat- 
 Fig. 380. 
 
 ings of both the jar and the battery. The rods R, R, are so 
 united with a hinge that the balls may be made to come in 
 
420 THE ELECTROPHORUS. 
 
 contact with the surfaces, or to be removed from them by 
 means of the insulating glass handles, which are attached to 
 the legs. This arrangement gives the power of discharging a 
 jar of almost any size, by removing or approximating the 
 handles. A very effectual and cheap discharger is made of a 
 piece of thick wire, about twelve inches long, curved and ter- 
 minated by a bullet at each end. 
 
 OTHER MEANS OF PRODUCING ELECTRICITY. 
 
 The Ulectrophorus. — This important instrument, Figure 
 381, may in many cases be made to take the place of the 
 
 common electrical machine. A 
 
 Fig- 381. mixture of equal parts of common 
 
 r\ resin, shellac and Venice turpen- 
 
 jl tine, is melted and kept in a state 
 
 , § of fusion at a temperature between 
 
 ^^j^^M^^^^^ 230° and 240° of Fahrenheit, until 
 
 |r^ ^t^^^^^^^ nearly all evolution of vapor has 
 
 ^^^^^^^^^^^^^p ceased and the fluid is quiet. It 
 
 ^ mmmni^^'^ jg allowed to cool to the point of 
 
 thickening, and is then poured care- 
 fully, so as to avoid the formation of air bubbles, into a circular 
 metallic tray or dish, of about nine or twelve inches in diameter, 
 and half an inch in depth. The resinous surface should be as 
 even and smooth as possible. A wooden box, or a receptacle 
 made by placing upon a smooth board a wooden hoop, are 
 less costly and do not expose the resin to the risk of cracking 
 from the sudden contraction of the metal, which is apt to 
 occur after its expansion by heat. Upon the smooth surface 
 formed by the cooled mixture, is placed a metallic disk, or one 
 of wood smoothly covered with tin foil, either of which is 
 provided with an insulating handle of glass or sealing wax, 
 which is inserted in its centre, above. This disk should be 
 somewhat less in diameter than the surface of resin. The top 
 has usually attached near its edge, a wire terminating in a 
 metallic ball, from which the spark is taken. 
 
 When this electrophorus is used, the cover is removed, and 
 the surface of the resin having been dried and slightly 
 warmed, is rubbed or whipped briskly with a piece of dry 
 flannel, a silk handkerchief, or the fur of a cat or hare's foot. 
 
Henley's quadrant electrometer. 421 
 
 After excitation by this means, the cover is lifted by its 
 handle — also dry — and is replaced upon the surface of the 
 resin. A spark will now pass from the knob of the cover to 
 the knuckle, or a metallic body held near it. Upon raising 
 the cover again, another spark of greater intensity than the 
 first will be received. A spark like the first, will be given by 
 the knob after the replacing of the cover, and again upon its 
 withdrawal, one similar in character to the second will be 
 given ofi", and in this way the experiment may be repeated 
 almost indefinitely if the weather is favorable. 
 
 The action of the machine is explained in this manner. 
 The negatively excited cake of resin acts inductively upon 
 the electricity inherent in the cover, attracting and combining 
 with its positive element, and repelling its negative one, which 
 accumulates in the upper part of the cover. When the top 
 of the cover is touched, the negative electricity escapes, and 
 the positive remains in combination with the negative kind of 
 the resin, as long as the latter is covered by the metallic 
 plate. But upon lifting this by the insulating handle, the 
 positive excitement is in its turn set free, and given oiF in 
 sparks from the knob. A similar succession of actions goes 
 on for some time, and the instrument has been known to give 
 sparks for weeks without being freshly excited. 
 
 To obtain strong positive sparks, it is necessary to touch 
 the cover when on the resin, with a finger or other conducting 
 body, and to remove it before raising the cover. To obtain 
 the strongest negative sparks, the cover when raised, should 
 be discharged of all its electricity against the hand or other 
 body before it is again placed upon the surface of the resin. 
 
 INSTRUMENTS FOR DETECTING AND MEASURING ELECTRICITY. 
 
 Henley's Quadrant Electrometer. — This instrument, chiefly 
 used to determine the amount of electricity present in the 
 conductor and in the Leyden jar, consists of a semicircle of 
 ivory or of wood covered with white paper, which is graduated 
 into 180 degrees, and fixed at its base to a wooden column. 
 In the centre of the semicircle there is a pin upon the column, 
 from which a movable radius terminated by a pith ball is sus- 
 pended. The column may be fixed in a hole in the conductor. 
 Upon working the machine, the column and the ball being 
 
422 
 
 BENNET S ELECTROMETER. 
 
 alike affected, the latter with its radius is repelled from the 
 former, and by the amount of the divergence the force is 
 exhibited in degrees. By means of this instrument, we are 
 enabled to ascertain when a jar, or battery in contact with 
 the conductor, is sufficiently electrified. During the accumu- 
 lation in the inner coating, the electricity is retained forcibly 
 by the attraction of the contiguous and oppositely electrified 
 surface, and will not be given off to an insulated body, or one 
 which is not in connection with the outer coating. But in 
 proportion as it ceases to be retained by this inductive action^ 
 and accumulates in the conductor, it raises the index of the 
 electrometer, often to a considerable height. When a battery 
 has received its greatest amount of charge, the ball seldom 
 rises above 40° or 50°, as the tension of the electricity never 
 equals that of a single jar, probably on account of the larger 
 surface exposed to induction. 
 
 Haiiy's Electroscope has already been described under the 
 head of the Blowpipe at page 383. 
 
 Bennetts Electrometer, — This instrument, more properly 
 called an electroscope, as it detects, rather than measures 
 electricity, is exceedingly delicate in its indications. It con- 
 sists in part of a glass cylinder, which may be similar in form 
 to the one shown in the drawing. A circular brass cap C, 
 
 covers tightly the vessel, and to its 
 centre is attached a metallic rod, 
 enclosed in a glass tube which is 
 well varnished with shell-lac, and 
 having attached to its ends two 
 slender strips of gold leaf, hanging 
 parallel to each other. Two strips 
 of tin foil T T, are pasted upon the 
 inside of the glass, with their upper 
 ends a little above the level of the 
 depending extremities of gold leaf, 
 and their lower ends connected with 
 the metallic bottom of the glass 
 cylinder. When an electrified body 
 is made to approach the cap of the 
 electrometer, the gold leaves will 
 diverge, and if the excitement be 
 sufficiently powerful, will touch the tin foil and then return to 
 their former state of rest. 
 
 Fig. 382. 
 
bennet's electeometer. 423 
 
 The delicacy of Bennet's electrometer is much increased by 
 the addition of two metallic disks, one having its centre sol- 
 dered to the side of the cap of the instrument, being in a 
 perpendicular position, and the other being attached to a rod 
 which is connected with the metallic foot of the instrument 
 by a hinge, so that it may be placed parallel to the other 
 disk, and so near as almost to touch it without actually doing 
 so. The presence of electricity in the metallic cap, and its 
 disk, induces the opposite kind in the contiguous metal, which 
 is then to be removed a few inches from its former position. 
 As this disk is connected with the base of the instrument, 
 and of course with the tin foil upon the inside of the glass, 
 that becomes also oppositely electrified from the cap, the con- 
 nected gold leaves of which diverge to a much greater degree 
 than in the simple instrument. This is called the condensing 
 electrometer. 
 
 Bennet's electrometer is the one in most common use, and 
 many circumstances of interest in reference to its employment 
 are worthy of note, particularly those connected with the 
 means of ascertaining the kind of electricity which causes its 
 gold leaves to diverge. 
 
 If an insulated conducting body containing electricity, such 
 as the prime conductor of the electrical machine, is made to 
 approach or to touch the cap of the electrometer, the leaves 
 diverge to a greater or less degree, in proportion to the ten- 
 sion of the electricity in the body, and remain separated, 
 gradually returning to their former position as the influence 
 passes off. In examining the condition of a body supposed 
 to be highly electrified, care must be taken not to make it 
 approach the cap too rapidly, as the result of a sudden and 
 powerful communication of the agent is very often the im- 
 mediate separation and tearing of the gold leaves. When a 
 non-conducting body, electrically excited, — a piece of sealing 
 wax, for instance, — is brought near to, or in contact with the 
 top of the instrument, the same divergence takes place ; but 
 it is temporary, as upon the withdrawal of the body the 
 leaves come together again. To make their separation as last- 
 ing as in the former case, it is necessary either to allow the 
 body to remain for a time upon the cap, or to rub it over its sur- 
 face, so that it may communicate its electricity from a number 
 of points. So far, the electricity of either kind, imparted to 
 the cap, has been that of conduction. But if the electrified 
 
424 INDICATIONS OF THE KIND OF ELECTRICITY. 
 
 body be held so near to the cap, as just to cause the diverg- 
 ence of the leaves, that divergence will diminish gradually 
 until the leaves finally collapse. If now the body be removed 
 to such a distance that it can scarcely afiiect the leaves, they, 
 after coming together, will often gradually diverge as before. 
 This second separation is caused by induction, and when it 
 occurs, the opposite kind of electricity to that existing in the 
 body will be found to be present in the cap and leaves. The 
 same effect is produced by touching the cap with the hand, 
 while the leaves are diverging from the electricity of the 
 excited body, by removing the hand after the collapse occa- 
 sioned by its first contact, and by then withdrawing the elec- 
 trified body, as before, to a greater distance from the cap. 
 
 It is well known that a piece of sealing wax, rubbed with 
 warm flannel, becomes negatively electrified and that a glass 
 tube rubbed with a silk handkerchief, becomes positively af- 
 fected. These facts present us with the means of determining 
 the kind of electricity which is transferred to the cap and leaves 
 of Bonnet's electroscope. If — after the leaves have been made 
 to diverge by the approximation to the cap of an excited 
 body — the presence upon the top, of a piece of rubbed sealing 
 wax makes the divergence greater, the electricity in the body 
 is negative. If however, the leaves approach each other 
 slowly, or collapse at once, the electricity is more or less posi- 
 tive. In the same way, a warm tube of glass, rubbed with a 
 silk handkerchief, will increase the separation of the positively 
 electrified leaves, and diminish or annul it when they are ne- 
 gatively excited. 
 
 Coulomb's Electrometer. — All the instruments, above de- 
 scribed, indicate the presence of electricity, but give little idea 
 of its quantity. Coulomb's torsion balance gives us an ap- 
 proximation at least to a means of accurately measuring it, or 
 rather of comparing the amount of it found in one body with 
 that existing in others, or in the same body, at different 
 times. This instrument, as represented in Fig. 383, from 
 Golding Bird's Natural Philosophy, consists of a slender 
 beam, or thread of shell-lac B, having a gilt pith-ball attached 
 to one end, and a little vane of paper to the other, and sus- 
 pended at its centre by a fine metallic wire, or what is better, 
 a delicate filament of spun glass. This ascends in a cylin- 
 drical or square frame of glass, and its upper end terminates 
 
coulomb's electrometer. 
 
 425 
 
 Fig. 383. 
 
 Si^:^^^ 
 
 in a key D, furnished with an index, the whole being capable 
 of moving easily in the centre of the circle 
 G^ which is graduated into 360°. A rod of 
 shell-lac -F, is inserted in the hole E, and 
 is prevented from falling down into the 
 glass cylinder which surrounds the whole 
 arrangement, by a stop at E. This rod 
 terminates in a gilded ball, which is called 
 the carrier ball, as it is used to convey to 
 the electrometer proper, the electricity of 
 the excited body. When this instrument 
 is to be used, the rod F is brought into 
 contact with the excited body ; its ball ac- 
 quires some of the electricity, and upon 
 being placed in the cage, it gives a part 
 of it to the ball of the lac beam. This 
 having now the same kind of electricity, is 
 repelled from the ball of the rod and de- 
 scribes a certain angle to its former posi- 
 tion, which it retains until it loses its electricity. To mea- 
 sure the amount of fluid thus acquired, the key D, to which 
 the glass thread is fastened, must be turned around, until by 
 the torsion or twisting of the latter, the ball of B is made to 
 come in contact with that of F. The number of degrees de- 
 scribed by the index, which is attached to the revolving key 
 D, gives an approximation to the proportion of electricity 
 derived from the contact of the ball of F with the electrified 
 body. 
 
 A more simple form of this electronometer, and the one 
 ordinarily described, consists of a lac needle with a gilt ball 
 at each end, suspended by means of a fine untwisted thread 
 of raw silk, which is fixed at top to a micrometer, by means 
 of which it can be turned around any number of degrees re- 
 quired. The whole is encased in a glass vase or cylinder, 
 with a tightly fitting top of glass, through a hole in the centre 
 of which the silk passes, the micrometer being above. Upon 
 the level of the suspended needle, a hole, drilled through the 
 sides of the glass, encloses a wire having a metallic ball at 
 either end, the inner one being nearly in contact with one of 
 the pith balls. The excited body is made to approach the 
 outer ball, and as in the instrument before described, the 
 movable knob separates from the other, and the quantity 
 28 
 
426 EUDIOMETRY. 
 
 of electricity is proportional to tlie distance to which it is 
 driven off. 
 
 APPLICATIONS OF ELECTRICITY. 
 
 Eudiometry. — Electricity proper is more often applied in 
 the laboratory of the chemist to the analysis of gaseous mix- 
 tures, by taking advantage of its power of exploding certain of 
 these, than to any other purposes. It is employed in connec- 
 tion with the eudiometer, an instrument which is used chiefly, 
 as its name indicates, to ascertain the purity of the atmo- 
 sphere, but in which the analysis of gases containing carbon 
 and hydrogen is also occasionally effected. In it, these latter 
 are made to unite explosively with oxygen, while in the exami- 
 nation of the atmosphere, the explosion of hydrogen with its 
 constituent oxygen, and the consequent production of water 
 and diminution of volume, enable the chemist to determine 
 the proportion of its ingredients. It would be foreign to our 
 purpose to give a full description of all the applications of eu- 
 diometry, but a short account of the means most commonly 
 employed, particularly in reference to the proper mode of ap- 
 plying the electric spark, will scarcely be at variance with the 
 practical nature of this work. 
 
 The Common Eudiometer is a short tube of thick glass, 
 having one end closed. This tube is graduated, and near its 
 closed extremity, two stout wires of platinum or other metal, 
 intended for the transmission of the spark, are inserted in the 
 opposite sides, their ends inside of the tube being a short dis- 
 tance apart. The other end of the tube serves for the intro- 
 duction and escape of the gas, and it remains constantly 
 immersed in the liquid over which the experiment is made, 
 the tube being supported in a perpendicular position. The 
 gas to be subjected to the spark, is generally such a mixture 
 as will inflame explosively at once, though sometimes a gra- 
 dual combination of some of its elements is effected by means 
 of a long-continued succession of sparks. The tube, being 
 filled with water or mercury, may be placed over the trough; 
 or for the purpose of more accurately determining the level 
 of the gas in the way about to be described, it should be sup- 
 ported over a glass vessel containing the proper liquid. The 
 gases are then successively introduced into it, in the proper 
 
THE COMMON EUDIOMETER. 
 
 427 
 
 proportions, after the manner described upon pages 134, 135. 
 To determine their volumes with the utmost degree of accu- 
 racy, it is necessary to support the tube by a forceps or a 
 cork-lined clamp, as represented in the figure, and not be- 
 
 Fig. 384. 
 
 tween the fingers, so that their temperature and volume shall 
 not be increased by the heat of the hand. To ensure that the 
 gas be submitted to no more pressure than that of the atmo- 
 sphere, the eudiometer should be raised in such a manner 
 that the interior level of the liquid contained in it, shall be 
 exactly at the same height as that of the liquid in the vessel 
 outside. In order to secure this, it is necessary that the eye 
 of the observer be in the same plane as the two levels of the 
 liquid, and that the line of the liquids in direct contact with 
 the glass inside and outside of the tube, be not taken as the 
 proper standard. It must be recollected that — as the edge 
 of a surface of water, in contact with the glass, is elevated 
 above its true level by capillarity, and that of mercury in the 
 same circumstances is depressed — the lower line in the former 
 case, and the upper one in the latter, will give the true position 
 of the main surfaces. The exterior of the tube is now wiped 
 clean, so that no mercury or water in contact with the wires, 
 can conduct ofi* the electricity. The tube, kept upright, should 
 then be clasped firmly in the hand by its middle, and its lower 
 end, still under water, should be closed with slight force by 
 
428 THE EUDIOMETER. 
 
 the thumb or a finger of the unoccupied hand. This permits 
 the descent of the fluid, which is driven out by the force of 
 the explosion, while it does not allow its too sudden return 
 upon the subsequent contraction of the gaseous contents of 
 the tube, or the escape of any of the latter. 
 
 In using the eudiometer, we must take into account the 
 relative degree of explosibility of different mixtures. Thus a 
 mixture of oxygen and carbonic oxide expands when inflamed, 
 much less than one of oxygen and hydrogen or olefiant 
 gas. A large quantity of any mixture will of course increase 
 in bulk much more than a small one. The whole quantity of 
 gas contained at first in the tube, should be at least so small, 
 that after expansion it shall not occupy quite the whole of the 
 eudiometer. No more gas should be introduced for detona-' 
 tion than will occupy a sixth of its capacity at common tem- 
 peratures, and generally it will be advisable to employ much 
 less. 
 
 The spark which is intended to effect the detonation or 
 slow union of the gases contained in the tube, may be derived 
 from the electrophorus, the prime conductor of the electrical 
 machine, or the Leyden jar, the power of the last two being 
 of course greater, in the order in which we have spoken of 
 them, than that of the first. When the electrophorus is em- 
 ployed, one of the wires upon the side of the eudiometer is 
 placed in connection with a finger of an assistant, or with a 
 metallic chain, the other end of which hangs in the trough or 
 vessel over which the tube is supported. The ball of an ex- 
 cited electrophorus is then brought near to the other wire, and 
 the spark obtained from it, passing from wire to wire through 
 the interior of the tube, inflames the mixture, if it be of suffi- 
 cient intensity, and if all the other circumstances are favora- 
 ble. The ball upon the conductor of the electrical machine may 
 in the same way be made to approach one of the wires, with 
 usually a more powerful effect. The employment of the elec- 
 trical machine is particularly advantageous when it is desired 
 to pass a succession of sparks for a considerable time through 
 the mixture, for the purpose of effecting a gradual combustion 
 or combination of the gases contained in the tube. The use of 
 the Leyden jar is equally convenient for a single contact and 
 much more apt to be attended with success on account of the 
 greater size and force of the spark. One of the wires may be 
 connected with the external coating of the jar, by means of a 
 
ure's eudiometer. 429 
 
 chain or hooked wire, and a discharger or other conductor, 
 applied at one end to the ball of the phial, may be brought 
 near the other wire. When other means of connection are 
 not at hand, the operator, at the risk of receiving an unpleasant 
 shock, may grasp the jar in his hand and apply its ball to one 
 wire of the eudiometer, while he touches a finger of the other 
 hand to the opposite wire. To ensure the explosion of the 
 mixture, a spark of the largest size that can be obtained from 
 the electrical instrument, should be passed through it. Very 
 often, although a sufficient amount of electricity is given off 
 from the conductor of the electrophorus or electrical machine, 
 its effect is lessened by its communication from wire to wire, 
 as an electrical brush, or in a succession of small sparks. To 
 remedy this evil, a ball, half an inch or more in diameter, 
 should be placed upon the outer extremity of that wire which 
 is to receive the spark, and the latter should always be given 
 off from the surface of a ball of considerable size. 
 
 The wires of the eudiometer must be firmly fitted in their 
 places, and the openings in the glass through which they 
 enter should be hermetically closed around them. Before 
 filling the tube with gas, it must also be ascertained that they 
 are perfectly insulated. When the detonation is effected over 
 water, a film of it is apt to adhere to the glass and wires, both 
 internally and externally, which by its conducting power, 
 sometimes diminishes the force of the spark, or intercepts it 
 entirely. To prevent this, the outside of the tube and wires 
 must be wiped as dry as possible before applying the conduc- 
 tor. The top of the tube should be gently tapped so as to 
 shake off any particles of moisture adhering to it within. The 
 perfect transmission of a large spark is only secured by the 
 presence of the balls upon the ends of the wire and discharger 
 as before described. 
 
 Ures Eudiometer. — Analysis of gases by explosion is much 
 more conveniently performed by means of Dr. Ure's syphon 
 eudiometer, shown in Fig. 385. It differs from the other 
 eudiometer in being curved like the letter U, but like it, it 
 has the part intended to contain the gaseous mixture, gra- 
 duated and pierced by two platinum wires. It is usually about 
 twenty inches in length, and the third of an inch in internal 
 diameter. This instrument, like the other, may be used for 
 the analysis of various gases over either water or mercury, 
 
430 
 
 UEE S EUDIOMETER. 
 
 Fig. 385. 
 
 but as it is applied chiefly to that of atmospheric air over the 
 latter liquid, we will confine ourselves to a 
 short account of this employment of it. 
 When about to be used for an examination 
 of the atmosphere, it is filled with mercury, 
 and the required amount of air is intro- 
 duced into the open end, which is inverted 
 over the trough, as in the case of the use 
 of the other form of tube. This end is 
 then tightly closed with the finger, and 
 the tube is turned slowly so as to admit 
 the air into the graduated extremity. The 
 instrument is then held upright, and the 
 amount of air introduced is read off by 
 looking at the scale, after subjecting it to 
 atmospheric pressure by displacing, with a 
 stick thrust in, that portion of mercury 
 which is above the level of that in the graduated limb. This 
 having been accurately done, the open part is again filled with 
 mercury, closed with the finger, inverted into the liquid, and an 
 amount of pure hydrogen is introduced equal as nearly as can 
 be guessed to half the volume of the air. The quantity of hy- 
 drogen added is then accurately estimated by returning the 
 eudiometer to the erect position, equalizing the surface of the 
 mercury as before, and reading oft' its level. The instrument 
 is then held in the way represented in the figure, the thumb 
 firmly closing its aperture, and the knuckle of the fore-finger 
 touching the nearer platinum wire. The explosion is pro- 
 duced by the aid of the electrophorus, prime conductor, or 
 charged jar, as before described, the violence of the expansion 
 being moderated by the spring-like action of the air contained 
 in the open limb. The level of the mercury is again equal- 
 ized by pouring into the open side enough of it to produce 
 that result, and the volume of the gaseous mixture is then 
 finally read off. 
 
 The loss in volume of the mixture, which is produced by the 
 explosion, gives by a very simple process, the amount of oxy- 
 gen originally contained in the air. As hydrogen unites with 
 oxygen to form water in the proportion by measure of two to 
 one, one-third of the diminution must be due to the oxygen of 
 the air introduced. Thus, if 100 measures of air and 50 of 
 hydrogen have been introduced, and if the mixture contain 
 
GALVANISM. 431 
 
 only 87 measures after explosion, the diminution has been that 
 of 63 measures. One-third of this loss is equal to 21 mea- 
 sures, which represents the amount of oxygen in the 100 
 measures of the air first introduced. 
 
 The precautions spoken of in reference to the common eu- 
 diometer may with equal propriety be applied to this. 
 
 GALVANISM. 
 
 AH the forms of apparatus which are employed for the 
 purpose of producing a continuous electrical current, are called 
 galvanic circuits, and those in common use consist of two 
 metals, one more oxidable than the other, and of a liquid which 
 by its action upon the readily oxidized or active metal, causes 
 the development of the influence. The old voltaic pile and 
 the crown of cups are the most simple examples of galvanic 
 apparatus. The former consists of a series of disks of zinc, 
 and copper, platinum or silver, arranged in a column, each 
 piece of different metal having placed between it and its 
 neighbor, a disk of cloth or paper steeped in some liquid, 
 which acts chemically upon the zinc. The crown of cups is 
 differently arranged, but upon the same principle. A number 
 of cups are placed in a row or circle, each one containing an 
 exciting liquid, such as dilute sulphuric acid, and a plate of 
 zinc, and one of the inactive metal. The zinc of one cup is 
 connected by a wire with the copper or other metal of the 
 next cup, and the zinc of that is also connected with the cop- 
 per of the one beyond it. The two external plates of both 
 kinds of series have wires soldered to them, which are called 
 the poles. In this way a communication exists between all 
 the parts of the series, directly between the alternate plates 
 of the different cups, and indirectly through the liquid be- 
 tween those in the same cup. A simple circuit, as exhibited 
 by the most elementary form of either of these arrangements, 
 represents in miniature all the other kinds of voltaic apparatus 
 employed. Thus, if a single cup be used, containing a plate 
 of zinc and one of copper, immersed in dilute acid, and having 
 wires attached to them, the voltaic current is supposed to 
 be developed upon the surface of the zinc, along with its par- 
 tial solution and the evolution of hydrogen, to pass through 
 the liquid to the copper, and to be conducted through that 
 
432 
 
 WOLLASTON S BATTERY. 
 
 metal to the end of its wire, which forms the anode or posi- 
 tive pole. The end of the wire attached to the zinc is the 
 kathode or negative pole. When these poles are placed in 
 contact with each other, or with a conductor of the fluid, the 
 electricity originally developed upon the surface of the zinc 
 returns to it from the positive wire through the negative one, 
 and if the current be sufiiciently powerful, the various phe- 
 nomena of voltaic light, heat, electro-magnetism, chemical 
 decomposition and action on the living body, are capable of 
 being exhibited during this passage from pole to pole. 
 
 In most of the forms of compound circuits, where a number 
 of pairs of plates are arranged together in a battery, the 
 wire attached to the terminal zinc plate becomes the positive 
 pole, and that of the last copper plate the negative one. This 
 arises from the fact that in these arrangements the last two 
 plates are actually superfluous, not being so much producers 
 of the galvanic fluid, as conductors of that which has been 
 generated in the intermediate parts of the apparatus. 
 
 Our limits will scarcely permit a reference even, to very 
 many of either the theoretical or practical points connected 
 with the phenomena of this extensive subject, nor does it 
 come precisely within our province to notice the former at all. 
 We will therefore confine our attention to the construction 
 and uses of the forms of voltaic apparatus, which are the best 
 known and the most used in the laboratory of the chemist. 
 
 Fig. 386. 
 
 WoUaston's Battery, — This is the very best of the old 
 
wollaston's battery. 433 
 
 forms of the voltaic battery. It consists, as shown in Fig. 386, 
 of a number of zinc and copper plates, the latter entirely 
 encircling the former except at the edges, and the two metals 
 being kept apart by pieces of cork or wood. Each plate of 
 zinc is soldered to the one of copper which is before it in the 
 series, and the whole arrangement is screwed to a bar of dry 
 mahogany, which permits its elevation from or depression 
 into the acid. This is contained in an earthenware trough, 
 divided by partitions into compartments, each one of which 
 receives a single pair. The exciting liquid is made of a mix- 
 ture of 100 parts by measure of water, 2 J parts of sulphuric 
 acid, and 2 parts of strong nitric acid. In the same manner 
 that the shock of the Ley den jar is increased by combining 
 it with others in a battery, the power of this apparatus can 
 be multiplied to any desired extent, by uniting it by means of 
 strips of copper, passing from the zinc of one instrument to 
 the copper of another, with any desired number of similar 
 batteries. 
 
 The chief objection to the use of this and like forms of 
 apparatus is what is called the local action^ which in it is very 
 great, and which gives rise to a rapid diminution of power 
 and corrosion of the zinc. 
 
 The bubbles of hydrogen given off from its surface, adhere 
 to the zinc, preventing perfect contact with the exciting fluid ; 
 some of the electricity is dissipated by the escaping gas, and 
 the sulphate of zinc which is formed, is in part reduced to the 
 metallic state, in a crust upon the surface of the copper. All 
 of these circumstances form serious objections to the use of 
 this battery where a long continued action is desired. 
 
 When common zinc is exposed to dilute sulphuric acid, it is 
 rapidly dissolved, and this solution and loss of material in the 
 common batteries are excessive and entirely disproportional to 
 the amount of galvanic fluid given off'. This, which is the 
 local action, is supposed to arise from a number of little 
 voltaic circles being formed by the presence in the zinc of 
 particles of plumbago, and of other metals which excite the 
 rapid erosion of parts of its surface. This evil can only be 
 prevented by carefully amalgamating the surfaces of the zinc 
 plate. 
 
 A single pair of Wollaston's battery is very efficient in the 
 production of the phenomena which are due to the evolution 
 of a quantity of electricity, such as ignition and deflagration 
 
434 
 
 DANIELL S BATTERY. 
 
 on a small scale, the deflection of the magnetic needle and 
 the various electro-magnetic experiments. Its intensity or 
 electro-chemical power is very much increased as before stated, 
 by combining it with other similar arrangements. 
 
 The plates of the old form of voltaic apparatus should be 
 removed from the acid, and washed with water after the com- 
 pletion of each experiment, or if they are permanently con- 
 nected with the trough, the acid in it should be poured 
 out, and reserved for future operations. In Wollaston's 
 battery, the plates are taken out by elevating the mahogany 
 bar to which they are attached, are freed from acid and 
 metallic deposit by washing with water, and are then either 
 suspended over the trough by a cord attached to a sup- 
 port above, or are placed upon a tile or old table until their 
 next employment. As the acid solution soon becomes unfit 
 for use from the large amount of sulphate of zinc dissolved 
 in it, it must be removed after reaching a certain point of 
 saturation. The best evidences of the cleanliness and perfect 
 connection of the surfaces, and of the activity of the liquor, 
 are afforded by the constant bubbling up of hydrogen during 
 the action, and by the ordinary voltaic phenomena exhibited 
 at the poles. 
 
 DanielVs Constant Battery. — This is a far better form of 
 apparatus than the one last described, and has the advan- 
 tage over it of being comparatively permanent in its action. 
 The local action being obviated by the amalgamation of the 
 zinc, it is of course much more applicable to those purposes 
 of electro-chemical examination in which long continued and 
 uniform transmission of the fluid through a body is desired. 
 In its simplest form, it consists of a copper 
 cylinder A, 3 or 4 inches in diameter, and 
 from 6 to 18 inches in height, containing in 
 its interior a cell of porous earthenware or 
 of animal membrane, within which is sus- 
 pended a rod of zinc three-quarters of an 
 inch in diameter, which has been carefully 
 amalgamated by rubbing its surface with 
 mercury by means of a cloth previously 
 dipped in dilute sulphuric acid. The cell or 
 membrane containing the zinc is filled with a 
 mixture of one part by measure of sulphuric 
 acid and 8 parts of water, and the space between it and the 
 
 Fig. 387. 
 
daniell's battery. 435 
 
 outer copper cylinder contains a saturated solution of sulphate 
 of copper, the surface of which should be upon the same level 
 as that of the solution within the cell. The solution of blue 
 vitriol is prepared by pouring boiling water over an excess of 
 crystals of the salt, and stirring constantly until it is satu- 
 rated. 
 
 To this solution, a little sulphuric acid, never amounting to 
 more than one-tenth part by measure, of the whole, should be 
 added. In order that this liquid be kept concentrated, a lit- 
 tle perforated copper shelf, seen in the figure, is usually 
 placed upon the inside of the cylinder, within an inch or two 
 of the top. This is intended to contain a supply of crystals of 
 the sulphate. They are placed at the upper part of the liquid, 
 because that portion becomes exhausted first, and because the 
 saturated solution of the crystals in its passage downwards 
 dilBfuses itself equably. In the absence of the shelf, a strong 
 bag of loose texture, or a net-work of copper wire attached 
 to the top of the cylinder, may be used to contain the crystals. 
 
 Attached to each metal of Daniell's battery is a binding 
 screw to form connections. When wires are held in each of 
 these, and a communication from the cylinder to the rod is 
 made, a powerful current is produced. In the figure, the ex- 
 tremity of z represents the positive pole, and that of x the 
 negative one. In this arrangement there is no evolution of 
 hydrogen, and no local action upon the zinc or consequent 
 unnecessary erosion of its surface. The interior of the copper 
 cylinder becomes covered with a compact deposit of metallic 
 copper from the decomposition of the oxide by the nascent 
 hydrogen. 
 
 The intensity or power of producing electro-chemical de- 
 compositions of this battery, may be much increased by asso- 
 ciating it with a number of others. Ten pairs, so arranged 
 that the inactive metal of one is attached by copper wires 
 or strips, to the active metal or the zinc of the next, make a 
 most powerful compound circuit, quite sufficient for nearly all 
 the purposes of the chemist. 
 
 Daniell's battery may be constructed very simply and 
 cheaply, by immersing in a tumbler or jar containing a solu- 
 tion of sulphate of copper, a copper plate of the proper size, 
 bent into the form of a cylinder, and having suspended in its 
 centre upon a piece of wood supported on the top of the outer 
 vessel — an amalgamated zinc bar. This is surrounded by a 
 
436 
 
 smbe's battery. 
 
 piece of bladder or of the intestine of an animal, tied at its 
 lower part, and containing the acid liquor. Bags of very 
 firm sail cloth, well sewn, make excellent diaphragms and re- 
 sist the action of the acid for a long time. Cylinders made 
 by cementing coarse strong brown paper, at the edges and 
 bottom, also answer perfectly well. The terminal wires may 
 be soldered upon the top of the metals with which they are 
 to be connected, and the solution of sulphate of copper may 
 be kept saturated by the means before spoken of. Very little 
 chemical action upon the surfaces of these batteries goes on 
 when the voltaic circuit is not completed: nevertheless it is 
 proper always to pour out the contents of the diaphragm or 
 to disconnect the zinc bar after each use of them. The liquid 
 may be kept in a separate vessel, and employed in future 
 experiments. The solution in the outer cylinder may be al- 
 lowed to remain. 
 
 Smees Battery. — This simple and powerful apparatus is 
 chiefly used to excite the precipitations of metals in the Elec- 
 trotype or galvano-plastic processes. As commonly constructed 
 and shown in Fig. 388, it consists of two plates of amalga- 
 mated zinc, clamped to a piece of wood by 
 Fig. 388. means of a bent strip of brass, and fur- 
 
 nished with a binding screw. Between the 
 plates of zinc, is fixed one of platinized sil- 
 ver, connected at its upper end with ano- 
 ther similar screw. The silver is covered 
 o-ver with a thin layer of platinum, by first 
 roughening the surface with strong nitric 
 acid, and after washing, placing it in a 
 vessel of water acidulated with sulphuric 
 acid, to which a little chloride of platinum 
 has been added. A porous vessel of pipe- 
 clay or earthenware, or an animal mem- 
 brane, with a plate of zinc in its interior, and containing 
 dilute sulphuric acid, is then immersed in the other recepta- 
 cle, and the silver and zinc are connected together by a wire. 
 The platinum precipitates upon the silver surface as a dark 
 and granular but closely attached deposite. 
 
 This rough surface of the silver plate, presenting myriads 
 of minute conducting points, greatly facilitates the evolution 
 of hydrogen. The only liquid used to excite this battery 
 consists of one part of sulphuric acid, and seven of water. 
 
groves' battery. 437 
 
 The addition of a few drops of nitric acid makes it act with 
 greater intensity, but it is not advisable to use it unless the 
 silver is thoroughly covered with platinum. 
 
 Another form of this battery consists of a glass vessel like 
 a tumbler, on which rests the frame which supports the me- 
 tallic plates. As in the other, two screw caps on the top of 
 the frame allow the attachment of wires for the conveyance 
 of the current. One of these is connected with a central slip 
 of platinum foil, on each side of which descend amalgamated 
 zinc plates, connected above with the other screw. Like 
 Daniell's batteries, a series of these may be connected toge- 
 ther, by making communication between the alternate zinc and 
 platinum plates. 
 
 G-roves' Battery. — This is the most energetic battery known. 
 Its activity is very great, and though this prevents it from 
 being so well adapted for galvanoplastic operations, it is the 
 one generally employed for the development of magnetism, 
 and is in common use in the magnetic telegraph. 
 
 Various forms of this arrangement are met with, but in the 
 most common one, a strip of platinum foil, furnished above 
 with a screw cap, is immersed in a cylinder of porous earthen- 
 ware, filled with strong and pure nitric acid. This cylinder 
 is surrounded by another one of amalgamated zinc, also pro- 
 vided with a screw cap, standing on short legs, and divided 
 by a longitudinal opening in one side, in order to permit the 
 acid to circulate freely around it. It is placed in a glass jar 
 or tumbler, containing one part by measure of sulphuric acid, 
 and eight of water. When the circuit is completed by bring- 
 ing together the wires placed in the screws, the hydrogen from 
 the decomposed water in the outer vessel is not given off in 
 the gaseous state, but passing through the diaphragm, com- 
 bines with some of the oxygen of the nitric acid, reducing it 
 to nitric oxide. Some of this dissolves in the acid, and the 
 rest escapes in the form of dense red fumes of nitrous acid, 
 formed by its combination with the oxygen of the air. 
 
 This battery owes its intensity and rapidity of action to the 
 absorption of the hydrogen, the good conducting nature of the 
 materials, and the consequent concentration of the fluid. It 
 has been said to be, when properly prepared, about seventeen 
 times more powerful than that of Daniell. The great objec- 
 tion to its use arises from the escape of the irritating and poi- 
 
438 
 
 bunsen's battery. 
 
 sonous nitrous acid, which is sometimes so considerable as to 
 fill the apartment with the fumes. 
 
 Bunsen's Battery. — This is the same in principle as Groves' 
 battery, but is more economical, as a cylinder of porous coal 
 is used in place of platinum. It is represented in Fig. 389. 
 
 Fig. 389. 
 
 A B is a glass vessel filled up to B' B' with commercial nitric 
 acid. C and C are hollow charcoal cylinders, dipping into 
 the acid as far as B" B'', and resting on the edge of the glass 
 by a flange. A ring of zinc or copper P encircles the top of 
 the charcoal cylinder, and terminates in an appendage P', for 
 connecting it with the wire. D D, which are diaphragms of 
 porous earthenware, contain an amalgamated hollow zinc 
 cylinder Z Z, with its appendage P'^, also intended for com- 
 munication, and which is immersed in dilute sulphuric acid. 
 The connections are made by means of the clamp A B, Fig. 
 390, and screw V, which are shown in place 
 at H, Fig. 389. The perfect contact of 
 these appendages, screws, and the ribbons 
 or wires of copper connected with them, 
 Hiust be secured, by keeping them clean 
 and bright by rubbing with sand paper. 
 When the battery is about to be used, the 
 glass vessel is half filled with equal parts of 
 ■commercial nitric acid and water, and the 
 diaphragm, with water acidulated with sulphuric acid. The 
 coal cylinder is prepared by pressing a thorough mixture of 
 
 Fig. 390. 
 3 
 
 / 
 
 u 
 
./■-.t^ ^i^l^'ii 
 
 ^-*yMX^ 
 
 "7 
 
 JZ 
 
 CONNECTION OF BATTERIES. 
 
 439 
 
 •+ 
 
 one part of caking coal and two of coke with a little rye flour, 
 into a cylindrical mould of sheet iron, in the centre of which 
 is a core of wood or pasteboard. The mould, after being 
 closed by a movable cover well luted on, is heated gradually 
 to redness, and the calcination is continued until the disen- 
 gagement of gas ceases. The cylinder is then taken out, 
 soaked in a strong solution of molasses, dried, and again cal- 
 cined by an intense heat, in order to increase its firmness of 
 texture. After this, its^ surface may be smoothed off with a 
 file, or in a lathe. 
 
 This battery is said to be almost equal to Groves' in power. 
 Professor Bird has constructed one similar to it by the use of 
 a black lead crucible. He ignited the crucible for a short 
 time, and, when thus prepared, filled it with nitric acid, and 
 wound a wire tightly around its outside, making it serve both 
 as a support and as the conductor of the fluid. A bar of 
 amalgamated zinc, also connected with a wire, was then placed 
 in a porous cylinder containing dilute sulphuric acid, and the 
 whole was immersed in the acid of the crucible. He states, 
 that, although powerful, it is much inferior to Groves' bat- 
 tery. 
 
 In the use of any of the above described batteries, care 
 must be taken not to fill either of the receptacles too full of 
 the liquid, since on immersing the metals or charcoal, some 
 part of it might overflow and mix with that of the other ves- 
 sel to the injury of the surfaces. After the insertion of the 
 cylinders or bars, the surfaces of the two liquids must be as 
 nearly as possible upon the same level; any ^deficiency in this 
 respect being compensated by the addition of more fluid. 
 
 Connection of Batteries. — The connection between the dif- 
 
 Fig. 391. 
 
440 WIRE FOR BATTERY PURPOSES. 
 
 ferent plates of batteries is very conveniently made by means 
 of the binding screw, Fig. 391. The wire by which the com- 
 munication is established, is passed through the hole in the 
 side, and kept in its place by the movable screw in the top. 
 The screw below, serves to fasten the arrangement firmly into 
 a hole of the proper size, in the top of either plate. The 
 operator should be supplied with a number of these, as they 
 permit him to unite and disconnect the different parts of an 
 apparatus with the greatest ease and rapidity. They are 
 shown in the figure, attached to the copper and zinc plates of 
 a simple circuit, with the wires, of which the ends form the 
 poles, passing through them. 
 
 Wire for Battery Purposes. — Copper wire is more often 
 employed for connecting the different parts of a voltaic cir- 
 cuit than any other, on account of its high conducting power, 
 its flexibility, and its not being susceptible of magnetization 
 by the passage through or around it, of a galvanic current. 
 Its thickness should be proportioned to the energy of the bat- 
 tery, and it should be as short as possible, because a great 
 length of wire causes resistance to, and loss of the fluid pro- 
 ceeding from a battery of moderate power. Its connecting 
 parts, as well as those of the plates or screws to which it 
 is attached, must be bright and clean. In order to ensure 
 perfect contact, it is advisable to amalgamate the extremities 
 of the wire. This is readily done by washing them with a 
 solution of nitrate of mercury, and dipping them afterwards 
 in metallic mercury. 
 
 This coating is apt to oxidize, and thus to cause an inter- 
 ference with the complete connection. When this occurs, the 
 film of oxide is to be rubbed off, and the amalgamated surface 
 renewed as before. This may be done with perhaps greater 
 ease than in the former method, by placing a few globules of 
 mercury and a little tallow upon a piece of chamois leather, 
 and then rubbing the wire with it until the mercury adheres 
 to its surface. When the second coating is applied in this 
 way, it is less apt to become tarnished than if made to adhere 
 by the aid of the solution of the nitrate. When it is desired 
 to break and renew the connections often or very rapidly, the 
 common mode of attaching the wires is found to be inconve- 
 nient. In that case, a little cup made of copper, or other metal 
 which does not too readily amalgamate with mercury, is partly 
 filled with that metal, and the wires are received in the cup, a 
 
ELECTROLYSIS. 441 
 
 depression in the bottom of the latter being often made so as 
 to hold them more firmly in their place. By keeping one of 
 the wires immersed in this cup, the connection may be made 
 complete or broken at will, and without disarranging any part 
 of the apparatus, by simply placing the extremity of the other 
 wire in its appropriate cup, or taking it out. 
 
 The wires are, in one point of view, the most interesting 
 parts of the battery, as it is at their extremities or the elec- 
 trodes, that the most important phenomena of galvanism are 
 exhibited. 
 
 Electrolysis. — Any one of the batteries already mentioned 
 mJly be employed for the purpose of producing chemical de- 
 compositions, by passing the current from them through the 
 substance, from pole to pole of the terminal wires of the series. 
 As electro-chemical changes are usually effected most per- 
 fectly by a current of intensity, as distinguished from one of 
 quantity, which is more active in producing light, heat, and 
 electro-magnetism, a number of pairs of plates or cylinders, 
 varying with the difficulty of the decomposition, are employed. 
 The other results spoken of are generally obtained by using 
 a small number of plates with large surfaces. A combination 
 of small batteries, made upon the plan of Daniell's is, per- 
 haps, the most active of all in producing chemical change. 
 
 Whatever form of apparatus is used for such decomposi- 
 tions, particular attention must be paid to the proper connec- 
 tion of the alternate metals, and to the close contact of the 
 wires, as well as the other circumstances before spoken of in 
 reference to their relative size. The points of the wires should 
 in most cases be made of platinum, as that metal is the best 
 conductor of the fluid, and is not liable to be chemically acted 
 on by any of the substances evolved from the electrolyte. 
 
 Any one of the class of bodies called electrolytes, which in- 
 cludes all those known to be capable of decomposition by elec- 
 tricity, may be exposed to the voltaic influence by being placed 
 between the electrodes or extremities of the wires, so as to be 
 the medium of communication between them. This is effected 
 in various ways, as the substances differ in being solid or 
 fluid, and good or bad conductors of the influence. 
 
 Many solutions, like that of iodide of potassium, admit very 
 
 readily of decomposition. A solution of this salt may be 
 
 easily decomposed by a battery consisting only of a wire of 
 
 zinc and one of copper. Water alone, however, may require 
 
 29 
 
442 
 
 ELECTROLYSIS. 
 
 the power of a number of cells of Daniell's battery to separate 
 it into its elements. The addition of a little common salt, or 
 of almost any saline body, will make the electrolysis of it 
 much more easy by increasing its conducting power. 
 
 In the decomposition of water, and indeed, in most cases 
 in which gaseous components of bodies are eliminated from 
 liquids, platinum strips are attached to the ends of the wires, 
 thus making the surfaces of contact much greater. These 
 strips, which may be made of platinum foil, are placed parallel, 
 and as close to each other as is possible without their being 
 actually in contact. Their touching each other would eifect- 
 ually prevent all chemical action, as the voltaic fluid would be 
 directly transmitted through the wires from the positive to the 
 negative plate. 
 
 When the electrodes are placed in a vessel of water, and 
 the battery is made to act properly, bubbles of hydrogen will 
 ascend from the end of the wire or foil connected with the 
 negative end, and oxygen from that of the positive one. 
 These gases can be collected in a tube closed at one end, or 
 ajar previously filled with water, and inverted over the wires; 
 or they may be separately received in different vessels. As 
 water consists of two volumes of hydrogen and one of oxygen, 
 of course the quantity of the first given off, will be twice that 
 of the last. Fig. 392 represents a mode of effecting this de- 
 
 Fig. 392. 
 
 composition in which the terminal wires of a trough arrange- 
 ment, are passed through a perforated cork into water con- 
 tained in a funnel. The end of each wire is placed directly 
 under a test tube previously filled with water, and inverted 
 
ELECTROLYSIS. 443 
 
 in the funnel. The ascending gases displace the water, oc- 
 cupy the tube, and may if necessary, be accurately measured. 
 
 As the quantity of electricity set in motion by the battery 
 is in direct proportion to the amount of zinc dissolved in it, 
 so are the effects of chemical decomposition always proportion- 
 ate to the former ; this being thus always in a certain rela- 
 tion with the equivalents both of the products of electrolysis, 
 and of the portion of zinc acted upon. Thus, one grain of 
 hydrogen, given off at the negative pole, indicates that thirty- 
 three grains of zinc have been dissolved during the time of 
 the action. Upon this principle Faraday constructed his vol- 
 tameter^ which affords the only means known of accurately 
 measuring the galvanic influence. That form of this which 
 is most employed, is one in which strips of platinum foil at- 
 tached to the wires of a battery, are placed opposite and near 
 to each other in a jar or bottle, from which a tube issuing, 
 enters under a graduated jar inverted over the pneumatic 
 trough, all of these vessels being full of water. By the mea- 
 sure of the gases collected, the quantity of electric force can be 
 estimated. By placing slips of platinum upon the ends of the 
 wires in Fig. 392, and substituting a single graduated tube 
 with a wide or funnel-shaped mouth, for the two which are 
 seen in the cut, the same result may be attained. 
 
 Faraday describes a convenient form of tube for the collec- 
 tion and examination of gases evolved from either electrode, 
 in experiments conducted upon a small scale. This tube, re- 
 presented in Fig. 393, is filled with the solution 
 to be acted upon, and held in the position re- Fig. 393. 
 presented. The nature of the gas to be col- 
 lected, depends on the end of the battery which 
 is fastened to the curved wire at a. The other 
 electrode is to be loosely inserted at 6, so as to 
 allow the gas given off from it, to escape through 
 the open orifice. It should not be placed so 
 far within the extremity of the tube as to per- 
 mit any bubbles of the gas to pass around the 
 bend, and to mix with that in the upright limb. ^ 
 The wire h is to be removed when a sufficient 
 amount of gas has been collected, and the latter can then be 
 transferred to a suitable vessel and examined. 
 
 The methods of subjecting substances to the action of the 
 battery are very numerous. When the electrolyte is a fluid, 
 
444 HEAT AND LIGHT FROM GALVANISM. 
 
 it may be placed in any one of a great variety of suitable re- 
 ceptacles. In all cases it must be recollected that the elec- 
 trodes should be brought as near together as possible, so that 
 the small amount of the substance which is directly between 
 them, shall have the full effect of the current concentrated 
 upon it. Decompositions of a drop of fluid may be made by 
 placing it upon a glass plate, and bringing the poles in con- 
 tact with its sides. Larger quantities may be received in a 
 watch-glass or other concave piece of glass, or in a cup of the 
 proper size. A very convenient mode of subjecting liquids to 
 the current, so that the results of the decomposition can be 
 easily inspected by the observer, is that of closing one end of 
 a piece of glass tube tightly with a cork, and supporting it in 
 an upright position by passing one of the wires of the battery 
 perpendicularly through the cork. The tube may then be 
 filled with the liquid, and the other wire, bent downwards, may 
 be immersed in it, and placed along side of its fellow. In 
 nearly all such decompositions, the ends of the poles should 
 be armed with strips of platinum foil, on account of the greater 
 surfaces of contact presented by them. 
 
 When it is desired to direct the electrolytic influence upon 
 a large surface of a liquid, a piece of platinum foil attached 
 to one pole may be hollowed out into a cup-like form, and the 
 substance may be placed in it; or the terminal wire may be 
 made to support, and communicate with a platinum crucible, 
 by being wound around it. The other wire can then be im- 
 mersed in the liquid, and prevented from touching the vessel 
 by the intervention of a piece of glass tube. 
 
 Production of Heat and Light by Galvanism. — The phy- 
 sical effects of galvanism, among which are the production of 
 heat and light, result generally from the passage of a current 
 of great quantity and of feeble intensity, through an insuffi- 
 cient or imperfect conductor, the resistance of the latter im- 
 peding the current, and increasing its calorific power. The 
 batteries employed for fusion and deflagration generally con- 
 sist of a very small number of pairs with extensive surfaces, 
 which will develope a great quantity of electricity. Usually 
 these are the best batteries for physical experiments, but oc- 
 casionally those consisting of a large number of plates are 
 found useful for such purposes. A single pair of very mode- 
 rate size will effect these results in a small way. Thus, Dr. 
 Wollaston fused a very fine wire of platinum by means of a 
 
HEAT AND LIGHT FROM GALVANISM. 445 
 
 small battery, made of a lady's thimble and a rod of zinc. 
 We have before stated that the intensity or decomposing power 
 of the galvanic fluid is increased by placing batteries in con- 
 nection so as to multiply the number of plates. Batteries 
 may also be associated together so as to increase their calorific 
 and light producing power. Any number of troughs like 
 Wollaston's may for this purpose be placed — not as before, 
 end to end — but sidewise, and the cells at either end of each 
 may be connected with the same cells of the others by two 
 wires, going across the series, and so bent as to be in perfect 
 contact with the last plates. The projecting ends of these 
 wires on one side are to be used as the poles of the battery. 
 
 Daniell's, or any other of the cell batteries, can be made 
 capable of producing the physical phenomena of electricity, 
 by paying attention to the size and conducting power of the 
 wires or other bodies to be heated; but the quantity of the 
 fluid is much increased by connecting a number of them so as 
 to make them equivalent to a single pair. This can be done 
 by connecting together all the copper or platinum plates by 
 means of wires, either soldered to them or inserted into the 
 binding screws already spoken of. The zinc bars or cylinders 
 are to be brought into contact in like manner, and the poles 
 may be made by attaching wires to any two of the opposite 
 pieces of metal. 
 
 The wires of such batteries should all be made of larger 
 size than those which are employed in the ordinary arrange- 
 ments. 
 
 "When the electricity developed in a powerful battery is 
 passed through conical pieces of charcoal placed upon its 
 poles, and these are brought into contact, and then withdrawn 
 to a short distance from each other, the interval becomes oc- 
 cupied with a brilliant spark or arch of flame, the light of 
 which is often too vivid to be borne by the eyes. The heat 
 given out is also very intense, and gases and other bodies are 
 sometimes subjected to its influence for the purpose of being 
 decomposed. Carburetted and sulphuretted hydrogen are 
 both thus aff*ected by it. The wires may be twisted around 
 two pieces of fine, well-burnt charcoal, which are then brought 
 together. The brilliancy of the spark or arch passing between 
 the points of charcoal, serves often to indicate the power and 
 good condition of the battery. When a very powerful cur- 
 rent is set in motion, it is advisable not to make the contact 
 
446 hare's sliding-rod eudiometer. 
 
 by means of the hands, but to use insulated dischargers analo- 
 gous to those employed in electrical experiments. The wires 
 may be brought together and disconnected by means of clamps 
 or small vices attached to wooden handles. These may be 
 screwed on and taken off at pleasure. The charcoal used in 
 these experiments must be of the best quality. It is properly 
 prepared by packing pieces of box or other suitable wood, two 
 inches long, and a quarter of an inch thick, in an earthenware 
 crucible, and, after covering them up with dry sand, heating 
 them until they cease to flame. The best pieces must be 
 selected and preserved for use in a well-stoppered vessel. 
 
 Various substances ignite and burn with brilliancy between 
 the galvanic poles. Metallic leaves or foil of different kinds 
 may be conveniently burned by taking them up upon the point 
 of one electrode, and bringing them in contact with a plate 
 of polished tinned iron, which is attached to the other. In 
 this way the different appearances and colors of their flames 
 are shown. 
 
 A platinum wire stretched between the poles of a battery, 
 will attain a red or white heat, and, if offering sufficient re- 
 sistance to the passage of the fluid, may even be fused. It 
 must not be too thin, as the electricity may be sometimes so 
 much retarded as to produce no visible indications of heat. 
 A wire of the proper size will often remain at a red heat for 
 a great length of time if a constant battery is used. 
 
 The power possessed by the battery of igniting platinum 
 wire, enables us to apply heat in situations in which it would 
 be difficult or impossible to do it by other means. By its 
 use, substances placed under water may be ignited or exploded, 
 if necessary, at a great distance from the operator. Out of 
 the laboratory, it may be employed for the purpose of ex- 
 ploding gunpowder in mines, or under ships, and in other posi- 
 tions far removed from the source of electricity; while, in it, 
 it may be used for the explosive decomposition of various 
 gases. 
 
 Dr. Hare has taken advantage of this power in the con- 
 struction of his sliding-rod aqueous eudiometer. This instru- 
 ment consists of a glass vessel, with a capillary orifice closed 
 by a spring and lever in its top, and connected below with 
 a socket, and a tube in which a graduated piston moves. A 
 fine wire of platinum is stretched across the middle of the 
 vessel, between two brass wires, which pass through the socket 
 
hare's calorimotor. 447 
 
 below, and terminate in legs, which are made capable of con- 
 nection with the cups upon the poles of a battery. The instru- 
 ment having been filled with water, the gaseous mixture is 
 drawn into it in the proper quantities by pulling out the pis- 
 ton to regulated distances, and is then exploded by the igni- 
 tion of the wire, after the capillary orifice has been closed. 
 This last is now again opened, but under water, enough of 
 which enters to supply the vacuum produced by the condensa- 
 tion. The amount of undecomposed air which remains, is 
 indicated by the distance through which the rod has to be 
 passed for the purpose of expelling it all from the glass 
 vessel. 
 
 Dr. Hare uses for the ignition of the wire in this experiment, 
 his calorimotor of two pairs of plates. He has constructed a 
 variety of arrangements for procuring the heating efi^ects of 
 the battery. In one of these, twenty sheets of copper, and 
 the same number of zinc plates, united separately to two bars 
 of metal, were secured in a wooden frame, so as to leave a 
 space between them of a quarter of an inch. A rope passing 
 over a pulley, was attached at one end to the frame, and at the 
 other to a counterpoising weight. The frame could be lowered 
 by means of the rope into a cubical box containing the acid 
 liquor. Another form of Hare's battery is so constructed 
 that the vessel containing the acid is raised up to and lowered 
 from the plates, when necessary, by means of a lever connected 
 with pulleys. By this most convenient and powerful battery, 
 constructed with a new arrangement of the plates, the most 
 intense galvano-ignition and deflagration may be accom- 
 plished. 
 
 This apparatus, the description of which might, perhaps, 
 have been more properly introduced along with the account 
 of other batteries, is shown in Figs. 394 and 395. We ex- 
 tract the description of it from Hare's Compendium. 
 
 " The two forms of calorimotor represented by Figs. 394 
 and 395, have been much used by me for what is described 
 in my Compendium as "• galvano-ignition. '' (C, 335.) Within 
 any cavity, ignition of any intensity short of fusing platina 
 may be produced, by making a platina wire the subject of a 
 galvanic discharge from an instrument of this kind. I first 
 resorted to this process in the year 1820, for the purpose of 
 igniting gaseous mixtures in eudiometers of various forms. 
 In June, 1831, 1 applied it to ignite gunpowder in rock blast- 
 
448 
 
 HARE S CALORIMOTOR. 
 
 ing; and to this object it was subsequently applied, agreea- 
 bly to my recommendation, by Colonel Pasley, Professor 
 O'Shognessy, and others. 
 
 Fig. 394. 
 
 " This machine consists of sixteen plates of zinc, and twenty 
 plates of copper, each twelve inches by seven, arranged in 
 four galvanic pairs. The plates are supported within a box 
 with a central partition of wood, A B, dividing it into two 
 compartments. Each of these may be considered as separated 
 into two subdivisions, by four plates of copper between the 
 letters C C. Of course the box may be considered as com- 
 prising four distinct spaces. No. 1, No. 2, No. 3, and No. 4. 
 The circuit is established in the following manner. Between 
 
THE GALVANOMETER. 449 
 
 the zinc plates af compartment No. 1, and the copper plates 
 of compartment No. 2, a metallic communication is produced, 
 by soldering their neighbouring corners to a common mass of 
 solder, with which a groove in the wooden partition between 
 them is filled. With similar masses of solder, two grooves 
 severally made in the upper edges of each end of the box are 
 supplied. To one of them, the corners of all the copper plates 
 of space No. 1, and the zinc of space No. 4, are soldered. To 
 the other, the zinc plates of space No. 2, and the copper plates 
 of space No. 3, are soldered in like manner. Lastly, the zinc 
 plates of No. 3 are connected by solder in a groove, and the 
 copper plates of No. 4 are in like manner connected by solder 
 in another groove. Upon the ends, SS, of the solder just 
 mentioned, the gallows screws are severally soldered, and to 
 these the rods, P P, called poles, are fastened. The means by 
 which the acid is made to act upon the plates must be suffi- 
 ciently evident from inspection. Depressing the handle causes 
 the wheels to revolve, and thus, by means of the cord which 
 works in their grooved circumferences, to lift the receptacle 
 which holds the acid, until this occupies the interstices between 
 the plates." 
 
 Means of Detecting the Galvanic Fluid. — The Galvano- 
 meter. — If a common magnetic needle, supported upon its 
 pivot, be placed directly under and parallel to a wire which 
 is connected with the poles of a galvanic circuit, so that the 
 positive fluid will pass through the wire from the north to the 
 south, it will, during the passage of the current, leave its po- 
 sition in the magnetic meridian, and, after a few oscillations, 
 assume one nearly or quite at right angles to it, its northern end 
 or austral pole pointing to the east, or to some point between it 
 and the north. Precisely the same eflect will be produced if 
 the needle is placed over the wire, and if the direction of the 
 current is reversed. But the northern end will be turned to- 
 wards the west, if the current is passed from the north to the 
 south while the wire is under it, and also in the same direction 
 if the wire again placed over it, transmits the fluid from the 
 south to the north. The needle always returns to its former 
 position immediately after disconnecting the wire. The power 
 possessed by a galvanic current of influencing the magnet, 
 may be increased to almost any extent, by passing it through 
 a number of wires, or a coil made of a single one, so as to make 
 the action of the whole equivalent to the sum of the actions 
 
450 THE GALVANOMETER. 
 
 of all its spires. This can be done most effectually by bend- 
 ing a long wire, covered with cotton or silk to prevent the 
 lateral escape of the current, into the form of a rectangle. 
 The needle is supported parallel to, and between its horizon- 
 tal branches, and it is obvious that it will be similarly affected 
 by each part of the coil, in whatever position its wires may be ; 
 for, as before stated, a current passing above it from the north 
 to the south, and one passing below from the south to the 
 north, cause it to deflect in the same direction. This instru- 
 ment is the galvanometer, or the '' electro-magnetic multiplier' 
 of Schweigger. By its use we can detect traces of electricity 
 much too minute to act on the gold-leaf electrometer; but its 
 chief applications are to the discovery of delicate galvanic 
 currents, and to the determination of their direction. As 
 
 Fig. 396. 
 
 shown in the figure, it consists of the coil of covered copper 
 wireNBS, containing usually about twenty convolutions, of 
 which the extremities are connected with the cups C Z. A 
 card graduated into 360° is fixed to the board A, so that a 
 line drawn between the numbers 360 and 180, coincides with 
 the direction of the centre of the coil. Above this is placed 
 a delicate magnetic needle, supported on a pivot. The coil 
 is placed with its long axis in the magnetic meredian. If any 
 source of feeble electricity is now connected with the cups, 
 the current from it will pass through the coil, and the magnet 
 will move to the east or west, according to the direction of 
 the fluid. The intensity of the influence is estimated in de- 
 grees, by comparing the position of the utmost divergence of 
 the needle with the number under it on the card. The deli- 
 cacy of this instrument depends in a great measure upon the 
 number of convolutions of wire. Thus, if all other circum- 
 stances are favourable, it may be supposed that one consisting 
 of one hundred turns will detect an amount of electricity 
 which is only one-fifth as great as that shown by the one with 
 twenty convolutions. 
 
THE ASTATIC GALVANOMETER. 
 
 451 
 
 The Astatic G-alvanometer. — The sensibility of the common 
 galvanoscope may be almost indefinitely increased by connect- 
 ing the magnetic needle immovably with another one placed 
 above the rectangular coil of wire, but parallel, and opposed 
 in the direction of its poles to the first. They are fastened 
 by their centres to a common axis, which revolves freely in 
 an aperture of the upper branch of the coil. This axis is sus- 
 pended by a fibre of silk to the upper part of the glass or 
 other vessel in which the whole is encased, and it penetrates 
 a graduated card, placed under the upper needle. This ar- 
 rangement makes the needle a balance of torsion, the move- 
 ments of which are compared with the degrees marked upon 
 the card, in the same way as in the simple multiplier. Ter- 
 restrial magnetism has scarcely any effect upon this system of 
 needles, and would have none at all if both possessed an equal 
 amount of magnetic power, the tendency of the one to assume 
 its position in the meridian being in that case entirely coun- 
 teracted by the reversed direction of the other. By a refer- 
 ence to the statements at the head of this article, it will be 
 seen that a current passed through the coil, in either direc- 
 tion, will have the same efi'ect upon both needles. Fig. 397 
 
 Fig. 397. 
 
 represents two of the many forms of Nobili's galvanometer. 
 It is called astatic because it is unafi'ected, or nearly so, by 
 the magnetism of the earth. 
 
 As these instruments are used not only to detect currents, 
 but also to ascertain the directions in which they pass through 
 
452 CONSTRUCTION OF FORMULAE. 
 
 the wires, it is of importance to impress upon the mind the 
 movements of the needles which indicate that one or other 
 extremities of the coil are in connection with the positive or 
 negative electric poles. A simple aid to the memory is to 
 suppose that a current is passing around the middle of a 
 watch, from the handle over the face, and is returning back 
 to its place of origin. The minute hand, if pointing to the 
 hour twelve, which is usually placed next to the handle, may 
 be supposed to represent the northern half of the needle. 
 It would then move around in its usual direction towards 
 the figure three. If the current were passed around the 
 back of the watch from the handle, and returned to the face, 
 the hand would move backwards towards the figure nine. 
 Ampere has devised the following formula, which is still better 
 calculated to impress the direction of the deviations upon the 
 memory. " Let any one identify himself with the current, or 
 let him suppose himself to be lying in the direction of the 
 positive current, his head representing the copper, and his feet 
 the zinc plate, and looking at the needle, its north pole will 
 always move towards the right hand." The person must, 
 however, suppose himself to be lying over the needle, his head 
 and its north pole being both in the same direction. 
 
 Our limits would not permit us to refer to the applications 
 of galvanism to electro-magnetic apparatus, or the electrotype, 
 even if these were more pertinent than they are to our sub- 
 ject. A full account of them is to be found in a number of 
 popular treatises. ''Davis Manual of Magnetism,'' and 
 Walker's ''Electrotype Manipulations,'' contain a full de- 
 scription of all the means employed in experiments on these 
 subjects, and of their practical applications. 
 
 CHAPTER XXXI. 
 
 CONSTRUCTION OF FORMULA. 
 
 All compounds are either mechanical mixtures following no 
 precise law, or consist of simpler bodies united in definite pro- 
 portions agreeably to the laws of chemical attraction. The 
 latter may be represented by formulae. 
 
CONSTRUCTION OF FORMULA.. 453 
 
 There are many advantages attending the employment of 
 formulae, and nothing has tended to advance the science of 
 chemistry further and more rapidly than their use. They 
 convey to the eye, like pictures, a far clearer view of the 
 nature of a compound than the most labored description could 
 eiFect. While they are established by analysis, their reaction 
 tends to confirm or disprove its results. As they are pic- 
 torial representations, the memory may retain the composition 
 of thousands of compounds, and yet not be overburdened. 
 Isomorphous bases may be thrown together under a short and 
 general expression, and thus substances, often differing widely 
 in external properties, are brought into natural groups, a re- 
 sult to which the analysis of a body would never lead without 
 the formula. 
 
 When a definite compound has been separated by analysis 
 into its constituent parts, their relative proportion is generally 
 expressed in per centages, but such a mode of expression does 
 not convey a clear idea of the chemical nature of the body, as 
 compared with other compounds, containing the same or 
 allied constituents. The per centage composition is usually 
 given as simply expressing the results of analysis. To ascer- 
 tain the nature of the union among the constituents, agree- 
 ably to the received laws of affinity, they must be reduced 
 from their per centage proportion to the proportions of their 
 equivalents. If any one of the constituents happens to 
 express in the per centage results, the combining weight of 
 that body, the others will also express their combining weights 
 or multiples of them. Or if any one can be multiplied or 
 divided by any number, which will give the combining weight 
 of that body, the others multiplied or divided by the same 
 number, (in order to keep up the same proportion as in the 
 per centage results,) will express their combining weight or 
 multiples of them. 
 
 Thus the analysis of carbonate of lime, according to 
 Dumas (1), and Erdman and Marchand(2), gives — 
 
 1 2 -4-2 
 
 Lime 56.06 56 28 
 
 Carbonic acid 43.94 44 22 
 
 100.00 100 50 
 
 If the 44 carbonic acid be divided by 2, it gives the com- 
 bining weight of one equiv. of the acid ; and the lime if divided 
 
454 CONSTRUCTION OF FORMULA. 
 
 also by 2, gives the combining weight of one equiv. of it. It is, 
 therefore, composed of 1 equiv. of each constituent. Again, 
 if b6 be divided by the combining weight of lime, 28, the re- 
 sult is 2 ; and 44 divided by the combining weight of the acid, 
 likewise gives 2. The proportion between the equivs. is, 
 therefore, 2 : 2 , or reduced to the lowest term 1 : 1. 
 
 Now since the per centage composition expresses the pro- 
 portion between the combining weights of the constituents, 
 if each constituent be divided by its combining weight, the 
 result will be the proportion between the number of equiva- 
 lents in the compound. 
 
 Then the lowest of these numbers divided by itself gives 
 unity ; and the others divided by the same number will express 
 the proportion between all the equivalents, and generally in 
 whole numbers, if the analysis has been correct. Thus the ana- 
 lysis of blue vitriol, by Berzelius, gives the following numbers 
 in the 1st column, expressed in 100 parts. 
 
 Oxide of copper 32.13 0.803 1.018 1 
 
 Sulphuric acid 31.57 0.789 1.000 1 
 
 Water 36.30 4.0333 5.111 5 
 
 The constituents being severally divided by their combining 
 weights, the numbers in the 2d column result ; and by dividing 
 each of these by 0.789, we get the 3d column, which, by 
 making a slight allowance for the imperfections of analysis, 
 gives the proportions between the equivalents 1:1:5. 
 
 Having determined the number of equivalents, a formula is 
 easily established, which in the case of carbonate of lime is 
 CaO,C02, and of blue vitriol CuO,S034-5HO. Now the per 
 centage composition of dry or anhydrous sulphate of copper 
 is 50 oxide of copper and 50 sulphuric acid. If we compare 
 it with the per centage composition of blue vitriol, the relation 
 between them is not readily seen ; and in the case of many 
 other substances, no relation whatever can be detected; but 
 if the formulae deduced from each analysis be compared, their 
 relation is at once evident, for we perceive that the blue 
 vitriol contains 5 equivalents of water, which the other does 
 not, and that otherwise they are one and the same substance. 
 
 The silicates form a numerous class of crystallized minerals, 
 whose formula may be established by the foregoing method, 
 or by determining the quantity of oxygen in each element, 
 and bringing these quantities into whole numbers, those of 
 the isomorphic bases being added together. It is, perhaps, a 
 
CONSTRUCTION OF FORMULAE. — GLASS-BLOWING. 455 
 
 more convenient method for these bodies than the preceding. 
 The construction of the formula for an organic body depends 
 on precisely the same principles, and is ascertained by a 
 similar process ; but there is a peculiarity in the formula of 
 organic bodies, which is rarely met with in mineral substances. 
 Thus the analysis of defiant gas gives as its formula CH ; but 
 from its density and other circumstances it should be C2H2 or 
 C4H4. The formula deduced from the analysis of sugar is 
 CHO, but it decomposes into alcohol and carbonic acid, and, 
 therefore, either C2H30 + C02=C3H303 ought to be the for- 
 mula, or CgHgOg or C^fi^fi^^y which last, indeed, is most gene- 
 rally received. A formula may also be doubled, or trebled, 
 if viewed as a bibasic or tribasic acid. Therefore, after de- 
 termining the simplest formula for an organic body, its more 
 rational formula is determined by the specific gravity of its 
 vapor, by its mode of combining with bases or acids, or by 
 its metamorphoses. 
 
 CHAPTER XXXII. 
 
 GLASS-BLOWING. 
 
 The ability to work glass over the lamp or blowpipe-flame 
 is a very desirable accomplishment for the chemist, as it ena- 
 bles him to fashion for himself, and in accordance with his 
 own judgment, such micro-apparatus as is constantly in de- 
 mand during experimental research. The inconvenience and 
 expense of having a large stock of delicate glass instruments 
 always at hand, and the difficulty of obtaining such at all 
 times, especially in localities distant from the cities, render 
 instruction in the art doubly desirable. On these accounts, 
 we think it proper to devote a chapter to a few illustrations 
 of the processes by which tubes are bent, closed, rounded, 
 widened, and drawn out, and by which bulbs are blown and 
 joints sealed. 
 
 The two principal pieces of apparatus required are a lamp 
 and a table blowpipe. The latter, as well as its management, 
 have already been written of at page 59. The former, known 
 
456 
 
 DANGER S GLASS-BLOWER S IMPROVED LAMP. 
 
 as Danger's "glass-blower's improved lamp," of form shown 
 by Fig. 398, is of sheet brass, and rests upon a tray designed 
 
 Fig. 398. 
 
 for the reception of any overflow of oil. These lamps are 
 fitted with an arrangement by which the wick may be raised 
 or lowered, and the flame consequently enlarged or diminished 
 as desired: an accompanying hood, serves to increase the 
 heat and to protect the eyes from the smoke and flame. 
 
 The wick may be made of common candle wick, divided 
 into lengths of proper dimensions, and stranded together, so 
 as to form a diameter of about three-fourths of an inch. This 
 bunch is placed in that part of the lamp intended as its re- 
 ceptacle, and should only protrude above the oil about the 
 third of an inch. When it is desired to lessen the power of 
 its flame, as may be necessary in the heating of small tubes, 
 the force of the blast can be diminished so as to make the 
 flame of the desired height and intensity. 
 
 The fuel may be olive, lard, sperm, or tallow oil ; — the latter, 
 however, being preferable on account of its giving a hotter 
 flame. In case of the absence of a lamp of this sort, any 
 common metallic vessel, of proper size, may be fitted for use, 
 upon the blowpipe table, by training up upon, and allowing 
 to overhang its side, a thick bunch of wick. This may be 
 kept in place, and its flame, at the same time, be prevented 
 from descending too far, by encircling it with a tin or other 
 metallic tube, or a coil of wire, which may be temporarily 
 connected with the sides of the vessel, so as to answer all the 
 intentions of support and the conduction off* of the excess of 
 heat. 
 
 S 
 
GLASS-BLOWING : — THE TABLE. 457 
 
 If the experimenter cannot have accefes to a properly made 
 blowpipe table, he may, in a very short time, construct a sub- 
 stitute himself, which, however rough, will enable him to carry 
 on nearly all the operations of glass-blowing. A hollow reed 
 or piece of cane angle, about a foot in length, may be firmly 
 fixed in a circular hole, drilled near the edge of a common 
 table, and which is just large enough to admit and hold it 
 firmly in its place. This may have adapted, by means of 
 cement, plaster or putty, to its upper end, a nozzle of metal, or 
 of glass drawn out to the proper sized orifice, or one made of 
 a piece of tobacco pipe of the requisite calibre. A bladder 
 of the largest size, or bag of caoutchouc, furnished with two 
 openings upon the same part of its circumference, is now 
 firmly attached to the bottom of this tube, by one of these a 
 similar piece of reed, long enough, however, to reach from the 
 operator's knees — while sitting — to his mouth, having been 
 inserted and tied into the other opening. That end, of this 
 last-mentioned tube, which is within the bladder, should be 
 provided with a valve, like that of a cupping glass, made by 
 placing, loosely over it, a long strip of oiled silk of the dia- 
 meter of the tube, folding the ends upon the body of the reed 
 and tying them firmly to it by waxed thread. This valve 
 admits of the passage of air into the receptacle, but will not 
 allow its return through the same orifice, so that pressure 
 upon the bladder will compel its exit through the nozzle of 
 the tube which is fixed in the table. If now the operator, 
 sitting near the table with the bladder hanging between his 
 knees and the loose tube fixed in his mouth, inflates the 
 former, and then presses upon it uniformly with his knees, a 
 continuous current is expelled from the nozzle upon the flame 
 of the wick placed directly above it. A repetition of the 
 inflation only becomes necessary when the bladder is nearly 
 emptied of its contained air. The inflation of this home- 
 made apparatus is scarcely, if at all, fatiguing, and it per- 
 mits to the glass-blower the unincumbered use of both his 
 hands. 
 
 The position of the jet upon the top of the table, and 
 that of the operator before it, are shown in the annexed 
 drawing. 
 
 When it is desired to use the gas flame, which is, however, 
 not so good as that of oil, the straight jet and Argand burner, 
 as is shown in the above drawing, are employed. It is still 
 30 
 
458 
 
 GLASS-BLOWING : IMPLEMENTS. 
 
 better, in ordering a blast table, to have prepared a jet, with 
 ball and socket joint suitable to either kind of flame, and 
 
 Fig. 399. 
 
 ^ \ W V 
 
 which can be screwed to, or removed from, the table at 
 pleasure. 
 
 The other implements are an iron piercer with wooden 
 handle. Fig. 400, a cone of biscuit-ware. Fig. 401, for widen- 
 
 Fig. 400. 
 
 Fig. 401. 
 
 Fig. 402. 
 
 ing the necks of tubes, a small pair of brass tongs, Fig. 402, 
 for fashioning bulbs, &c., a small piece of smooth hoop-iron. 
 
CUTTING OF GLASS. 459 
 
 styled the marver, a hardened cast-steel knife, and one or two 
 three-cornered files for cutting tubes and rods. 
 
 In addition to the above, the table should be supplied with 
 a stock of tubes and rods, of assorted diameters, and made of 
 glass free from lead. They should, moreover, be very uni- 
 formly regular throughout, and exempt from flaws or strise. 
 
 Before commencing operations, the wick must be evenly 
 trimmed and parted in the middle, so that when the jet is 
 placed opposite in the rear, and in proper relation, it may 
 drive the flame forcibly in advance, but not of too great 
 length, else it will become smoky. 
 
 The tubes or rods, previously divided* into the required 
 length, should always be wiped perfectly dry before being 
 subjected to the action of the flame, and then carefully and 
 gradually heated, the uniform diffusion of the heat being 
 effected by keeping them revolving ; — these precautions, which 
 are always to be observed, prevent breaking from sudden and 
 unequal heating. After being heated, they must be removed 
 gradually from the fire, and laid upon a piece of charcoal, so 
 as to become annealed, as it were, by gradual cooling. 
 
 The most simple and easily performed of all the operations 
 
 Fig. 403. 
 
 of glass-blowing, is the rounding of edges, which is readily 
 done by heating them to softness in the flame during constant 
 
 * Tubes can very readily be severed, or divided into lengths, by scratching 
 them with a file, and breaking asunder as at Fig, 407. For large tubes, the 
 scratch must extend entirely around the circumference. 
 
 Vessels of larger diameters, such as necks of retorts, and the like, require the 
 use of a diamond spark. According to Mr. Nasmyth, coke has the property of 
 cutting glass, and can very well be substituted for the diamond. 
 
 When the scratch of the file is insufficient to effect a smooth division, moisten 
 the scratch, and trace it with a heated wire or pastile. A heated wire will 
 also divert a crack in a glass vessel to any desired direction. 
 
460 TUBES CEMENTED. — TUBES BENT. 
 
 revolution of the tube between the thumb and three fingers, 
 which support it. This operation, by which the edges of 
 tubes and rods are smoothed, is also preliminary to that of 
 widening the mouth of a tube, a test-tube for example, which 
 is done by spreading it while hot, as shown in Fig. 403, by 
 means of the iron piercer, or, better, the biscuit cone, either 
 of them being previously warmed, and then carried round the 
 opening with an outward pressure. 
 
 Tubes Gemented. — Tubes or rods are also cemented together 
 by softening their ends and blowing gently through them at 
 the moment of junction. Care must 
 Fig. 404. "be taken to hold them firmly and 
 
 perfectly even, as shown in Fig. 404, 
 and to retain hold of the joined tube 
 until it has entirely cooled, else it 
 may bend by its own weight at the heated part, and thus be- 
 come crooked. 
 
 If the tubes to be cemented are of unequal diameters, the 
 
 wider one must be drawn out at 
 Fig. 405. its end, so as to reduce it to the 
 
 size of the smaller, and then be 
 joined to it as above directed, 
 and shown in Fig. 405. 
 
 Rods are cemented together 
 by partially fusing their ends and bringing them carefully 
 together, and pressing them until they adhere. The welding 
 is then completed by heating the new joint, during which 
 process, in order to impart shape, the rods must be kept 
 rotating, and be alternately drawn out and brought together, 
 until the junction is as smooth and uniform as any other part 
 of the surface. 
 
 Tubes Bent. — Very small tubes can be bent over the spirit 
 lamp. Fig. 115 ; but larger ones require the force of the 
 blowpipe-flame to heat them. The operation of bending con- 
 sists in heating the tube, to dull redness, about an inch on 
 either side beyond the point of the intended curve, and just 
 at the commencement of softening, in making an angle, by 
 bending it dexterously but slowly in the desired direction 
 until it assumes the required form. In order to prevent a 
 flat, wrinkled, and consequently very fragile elbow, it is ne- 
 cessary to close the tube at one end, and blow gently into the 
 
DRAWING OUT. — TUBES CLOSED. 461 
 
 otlier, during flexion, so that the pressure of the air within 
 may counteract any tendency to malformation. 
 
 Drawing Out. — When a tube is to be drawn out, either as 
 preliminary to further working, or in the preparations of 
 nozzles for washing bottles, or other purposes, one of the pro- 
 per size is taken, at the ends, between the thumb and index 
 of each hand, and along its length with the other fingers, 
 and kept revolving gradually over the flame until it becomes 
 red, and commences to soften at the heated part. It is then 
 taken from the fire and drawn apart, as shown in Fig. 406. 
 
 Fig. 406. 
 
 In this way also stirring rods are pointed, and when the tips 
 of either tubes or rods thus wrought are to be smoothed, it is 
 only necessary to divide, or break across the centre of the 
 part drawn out, and to heat the surfaces in the flame until 
 they soften and fuse. The pro- 
 per mode of severing glass rods ^^s- 407. 
 or tubes, is first to make a deep 
 scratch with a three-cornered file 
 in the spot where separation is 
 required, and then, after grasping 
 them as shown in Fig. 407, by gently breaking them apart. 
 
 The tube must not be kept in the fire too long, nor yet 
 drawn out too rapidly. When the tube or rod is too short to 
 be divided, it may be drawn out at either of its ends by means 
 of a punto — a piece of glass rod which is heated to softness 
 and cemented to the other as a handle. 
 
 Tubes Closed. — Very small tubes may readily be closed 
 by softening their edges over a flame, and rotating them until 
 they unite and adhere. Tubes of larger size are treated in 
 the same way, but to facilitate their closure, occasional pres- 
 sure of the hot end against the back of the tool. Fig. 402, 
 and sometimes gentle blowing through the open end, are re- 
 quired. Tubes also are closed hermeti- 
 cally by drawing out one end, as shown Fig. 408. 
 in Fig. 408, by then scratching with a 
 file and breaking asunder the part a, 
 and finally by closing the small orifice 
 by fusion in the flame. 
 
462 DRAWING OUT AND CLOSING. 
 
 Drawing Out and Closing, — When it is desired to form a 
 vessel like a test-tube, a tube of the required diameter is 
 drawn out, as at Fig. 409, and then cut asunder at a. The 
 
 Fig. 409. 
 
 Fig. 410. 
 
 two pieces thus formed, serve to make two test tubes. For 
 that purpose, it is necessary to heat the smaller end of each 
 to softness, and immediately upon removal from the flame, to 
 blow cautiously and slowly into the open extremity until the 
 closed end assumes a uniform spherical shape. Sometimes it 
 is necessary to repeat the heating and blowing in 
 Fig. 411. order to fashion the bottom perfectly, as seen in 
 Fig. 411. If the piece of glass is only long 
 enough to form one tube, its end can be drawn out 
 by attaching a punto, as before described, and now 
 shown at 6, Fig. 410. This punty, or glass rod 
 handle, serves also to remove any redundant glass, it being 
 only necessary for that purpose to heat the closed end highly, 
 to apply the punty a little less heated, and after collecting 
 upon its end as much of the surplus melted glass as is required 
 to make the bottom thin and capable of supporting sudden 
 changes of temperature, to draw it off. This manipulation 
 requires some dexterity, which is, however, easily acquired by 
 slight practice. If at one heating and gathering the bottom 
 has been reduced to the proper thinness, it may be heated 
 anew, removed from the fire, and then by slow and gentle 
 blowing, through the open end, the bottom may be blown out 
 to roundness. The mouth of the tube is then finished as di- 
 rected at page 460, Fig. 403. 
 
 Lateral Attachments. — To attach a tube to the side of 
 another is somewhat difficult. For this purpose, the tube 
 with which the junction is to be efiected is closed at one 
 end and heated at the desired point, such as 5, Fig. 412, to 
 high redness. To this hot part a glass rod, or punto e, 
 
LATERAL ATTACHMENTS : BULBS. 
 
 463 
 
 slightly heated, is attached and drawn out, as shown in the 
 figure. When the glass has cooled, cut off the new joint at 
 
 Fig. 412. 
 
 Fig. 413. 
 
 u 
 
 5, heat again in the flame, and widen its mouth with the tool, 
 Fig. 400, to the size of the diameter of the tube which is to 
 be joined with it. This having been done, the tube is to be 
 attached as directed at page 460. Fig. 413 shows the joint 
 perfected. 
 
 Another mode is to heat and close the drawn out end, and 
 to blow forcibly through the tube until the bulb, thus formed, 
 bursts. All the remains of the thin glass bulb being broken 
 off, a protruding aperture is left, to which the lateral tube 
 may be cemented, in the usual way, by heating the edges of 
 the ends of the two tubes to be united, joining them in the 
 flame with slight compression, heating the joint to redness, 
 and then slightly blowing, to give form and prevent cracking. 
 
 To Blow Bulbs. — To form a bulb at the end of a narrow tube, 
 it is only necessary to continue heating it after closure until it 
 commences to soften, and then immediately upon its removal 
 from the flame, to blow into the open 
 end, as in Fig. 414, slowly, until the 
 heated part expands to the proper size 
 and shape. Care must be taken to 
 heat the tube to a sufficient extent, so 
 that there may be enough glass soft- 
 ened to give a bulb of the required 
 size; — moreover, during both the heat- 
 ing and blowing the tube must be kept 
 slowly rotating between the fingers, so 
 as to prevent an accumulation of the 
 melted glass, by its own weight, in 
 any one part. 
 
 To blow a bulb in the middle of a 
 tube, the latter must be heated at its centre during constant 
 
 Fig. 414. 
 
464 glass-blowing: bulbs. 
 
 but slow rotation between tbe fingers, and then carefully 
 blown into at one end, whilst the other is closed with the 
 finger, a cork, or a piece of wax. The pressure of the air 
 within expands the hot glass into a spheroid, regular or irre- 
 gular in form, according to the care and skill of the operator. 
 The part of the tube to be expanded must be heated uniformly 
 and kept in constant and slow revolution during both the heat- 
 ing and blowing. 
 
 In the fashioning of certain glass-tube apparatus, it is 
 sometimes necessary to blow the bulbs separately, and to 
 attach them afterwards to their adjacent parts ; — the bulb is 
 then formed as follows. Take a glass tube A, Fig. 415, of 
 
 Fig. 415. 
 
 » n A. 
 
 the required diameter and length, heat it at the points a and 
 by and draw it out in two places, as shown at t* 8 in B. When 
 the tube has cooled, divide it at the attenuated parts r s with 
 the file, as directed at page 459, Fig. 407, and close one end 
 of one of the pieces in the flame. Then hold it by the other 
 end, which is drawn out, heat it to redness, and fashion the 
 bulb by blowing, as above directed, until it assumes the shape 
 of G. It is then cemented to the other parts of the ap- 
 paratus, as directed at page 460, the previous widening of the 
 drawn out parts being performed as at Fig. 403. 
 
 Thermometer bulbs are made by expanding, as above di- 
 rected, the heated end of tubes with a capillary bore. 
 
 To Make a Welter 8 Tube. — By way of illustrating the 
 dififerent operations of fashioning glass tubes over the blow- 
 pipe-flame, we will go through the diflferent stages of manu- 
 facture of the safety tubes of Welter. A straight tube is first 
 bent into form, as at A, Fig. 416, and the flame is directed 
 upon a ; as soon as the glass softens at that point one end of 
 the tube is closed with the finger, and the other is blown into 
 
GLASS-BLOWING : WELTER'S AND FUNNEL TUBES. 465 
 
 forcibly, so as to form the very thin, brittle bulb represented 
 
 Fig. 416. 
 
 l\ 
 
 _»A 
 
 X^ 
 
 ■1 
 
 
 
 i! 
 
 ^ 
 
 A. 
 
 by the dotted lines. When the tube is thick a repetition of the 
 heating and blowing is required. This bulb is then 
 broken off, and the bent tube, thus formed, is ready to ^ig- ^^'^^ 
 be attached to the straight tube B. This latter is 
 formed of a separate tube, and having a bulb h 
 blown into its centre, is cemented to A at a, in the 
 manner before directed. The funnel top of the 
 tube B, is formed by first blowing a bulb c on its 
 upper end to extreme thinness, removing it with the 
 file and cementing a bulb, with open mouth, as at 
 a; in D. The S form is given merely by bending B 
 in the proper direction. 
 
 Instead of an open hulh at the top of the D tube, 
 a small funnel is cemented to it, as in the fashioning 
 of funnel tubes, Fig. 417. 
 
466 CORKS : cork borer. 
 
 CHAPTER XXXIII. 
 
 CORKS. 
 
 Corks are in many ways indispensable for laboratory pur- 
 poses, and the stock should consist of all sizes; those for 
 mounting apparatus being necessarily of the finest velvet kind, 
 smooth and as free as possible from imperfections. 
 
 An excellent means of increasing the elasticity of corks is 
 compression by a small apparatus. Fig. 418, sold for the pur- 
 Fig. 418. 
 
 pose. This treatment renders them capable of being fitted to 
 apertures with great nicety and ease. 
 
 We have frequently made mention of the adaptation *'of 
 tubes and other parts of apparatus by means of perforated 
 corks. These perforations may be made with a hot metallic 
 rod and afterwards enlarged with a rat-tail file ; but a much 
 smoother and neater hole can be made with a cork borer, Fig. 
 
 Fig. 419. 
 
 419, which is intended specially for this purpose. It consists 
 
CORKS PERFORATED. 
 
 467 
 
 Fig. 420. 
 
 of a series of brass tubes of uniform length, but varying 
 from an eighth to one inch in diame- 
 ter, and fitting one within the other. 
 The sizes contained in such a series 
 are equal to all the requirements of 
 the laboratory, as holes of smaller 
 or larger dimensions than the above 
 extremes are seldom required. Each 
 of the tubes is open below, but closed 
 at the top with a cap c?. Fig. 420, 
 through which is a hole h for the 
 passage of a stiff wire c?, which serves 
 both as a handle and as a punch for 
 ejecting the cores from the tube 
 after the perforation of the cork. 
 
 The drawing exhibits one of the 
 tubes of the series already in opera- 
 tion, it being only necessary to bring 
 its base upon a cork, and to effect 
 the perforation by pressure upon the cap and a slight circular 
 motion. The core or part of the cork removed, ascends into 
 the barrel a of the tube and must be ejected by the force of 
 the punch d. As the tubes become dull on the edges, they 
 may be sharpened upon a grindstone or with a fine file. 
 
 As a familiar illustration, we exhibit in the Fig. 421 a cork 
 
 Fig. 421. 
 
 thus treated with tubes inserted in the perforations. Their 
 convenience is shown in many of the arrangements of which 
 we have given drawings. 
 
 When the corks are not of good quality, they may be ren- 
 dered impermeable by coating their surfaces with 8oft cement, 
 
 India rubber corks have lately appeared in the market ; — 
 they are made by Goodyear, and answer admirably as cheap 
 stoppers of bottles containing substances which are volatile, 
 and which do not corrode the caoutchouc. 
 
468 DEALERS IN AND MANUFACTURERS OP APPARATUS. 
 
 CHAPTER XXXIV. 
 
 DEALERS IN AND MANUFACTURERS OF APPARATUS. 
 
 For the convenience of those engaged in the study, prac- 
 tice, or teaching of chemistry, we here introduce the address 
 of a number of prominent dealers in and manufacturers of the 
 required furniture and reagents. From one or more of them 
 may be obtained each and every implement and article men- 
 tioned in this work. Some few issue catalogues of their 
 articles, with the price of each affixed, and furnish them 
 gratuitously upon application ; — their names are designated 
 in the list below by asterisks. 
 
 Joaquim Bishop, Laurel Street, Philadelphia; manufacturer 
 of platinum vessels, and of all kinds of chemical or philoso- 
 phical metallic apparatus. 
 
 Bently & Co., Baltimore; manufacturers of portable steam 
 generators ; Morris, Tasker & Co., Agents, Philadelphia. 
 
 Charles Button*, 146 Holborn Bars, London; dealer in 
 chemical apparatus, and manufacturer of pure chemicals. 
 
 J. P. Duffey, South Eighth Street, Philadelphia ; manufac- 
 turer of delicate balances, and of chemical and philosophical 
 apparatus generally. 
 
 Wm. Debeuist, University of Pennsylvania, Philadelphia; 
 manufacturer of metallic apparatus. 
 
 Joseph Fisher, 58 Chestnut Street, Philadelphia ; manufac- 
 turer of thermometers and hydrometers. 
 
 L. C. Francis, No. 13 Dock Street, Philadelphia; manu- 
 facturer of thermometers, barometers, and of metallic appa- 
 ratus. 
 
 James Green, Baltimore ; manufacturer of electrical and 
 other metallic apparatus. 
 
 Richard Griffin & Co.*, Glasgow, Scotland; dealers in che- 
 mical apparatus and reagents. 
 
 J. G. Greiner*, Berlin, Prussia, manufacturer of accurate 
 thermometers and hydrometers for experimental research. 
 
DEALERS IN AND MANUFACTURERS OF APPARATUS. 469 
 
 B. B. Gumpert, 120 North Second Street ; manufacturer 
 of electro-magnetic machines. 
 
 Hammet and Hiles, 128 Vine Street, Philadelphia ; manu- 
 facturers of copper hollow ware. 
 
 Haig & Co., 545 North Second Street, Philadelphia; manu- 
 facturers of blue stoneware. 
 
 Stephen Heintz, Queen above Warren, Kensington, Phila- 
 delphia } glass blower and manufacturer of all kinds of tube 
 apparatus. 
 
 Kartell and Lancaster, Union Glass Works, Kensington, 
 Philadelphia; manufacturers of tube apparatus, and of all 
 other kinds of chemical glassware. 
 
 Hansell, Pine, above Tenth Street, Philadelphia ; turner in 
 wood, and manufacturer of supports, clamps, and filter stands. 
 
 Edward N. Kent*, 116 John Street, New York ; general 
 depot for the sale of all kinds of chemical and philosophical 
 apparatus, and of pure chemicals. 
 
 Lindsay & Blakiston*, North-west corner of Fourth and 
 Chestnut Streets, Philadelphia ; publishers and importers of 
 scientific books. 
 
 Abraham Miller, Zane Street, Philadelphia ; manufacturer 
 of assay furnaces and of all kinds of pottery. 
 
 Alva Mason, South Fifth Street, Philadelphia; manufac- 
 turer of chemical and philosophical apparatus. 
 
 Powers & Weightman, corner of Ninth and Parrish Streets, 
 Philadelphia; manufacturers of acids and pure chemicals, and 
 of chemical glassware. 
 
 Z. Pike, New York; manufacturer of chemical and electrical 
 apparatus. 
 
 Mauldin Perrine, Baltimore ; manufacturer of blue stone- 
 ware retorts, adapters, crystallizers, digesters and other ap- 
 paratus, of the same material, for chemical uses. 
 
 Bullock & Crenshaw*, North-east corner of Sixth and Arch 
 Streets, Philadelphia; manufacturers of and dealers in pure 
 chemicals, glass and porcelain apparatus. 
 
 Savery & Co., corner of Reed and Front Streets, Philadel- 
 phia ; manufacturers of plain and enamelled hollow-ware of 
 iron. 
 
 Tatham & Brothers, Philadelphia ; manufacturers of smooth 
 lead-pipe. 
 
 L. Voigt, North Third, above Vine Street, Philadelphia ; 
 Agents for Storms and Fox's glassware. 
 
f 
 
 
 470 DEALERS IN AND MANUFACTURERS OF APPARATUS. 
 
 Jas. M. Wightman*, 33 Cornliill, corner of Franklin 
 Avenue, Boston ; manufacturer of metallic chemical and phi- 
 losophical apparatus. 
 
 E. Wight, No. 4 South Fifth Street, Philadelphia; manu- 
 facturer of philosophical apparatus. 
 
 Weiss & Schively, 43 North Front Street, Philadelphia; 
 importers of Beindorff's portable laboratories; of glass and 
 porcelain ware, and of fine drugs and chemicals. 
 
 Samuel Wenzell, corner of Queen and Palmer Streets, 
 Kensington, Philadelphia ; manufacturer of laboratory tables, 
 mineral cases, and wooden apparatus. 
 
INDEX 
 
 ABsonpTioN of gases, 257 
 Acids, filtration of, 361 
 Aikin's blast furnace, 155 
 Air chambers, 324 
 
 desiccation in, 324 
 pump, 59 
 
 eudiometrical analysis of, 426 
 Alcohol bottle for table use, 72 
 Alterable substances, desiccation of, 336 
 Amalgam for electrical machines, 412 
 Amalgamation of copper wires, 440 
 
 zinc plates, 434 
 Ampere's formula for the direction of 
 
 currents, 452 
 Analysis, record of, 53, 73 
 of gases, 426 
 by mouth blowpipe, 380 
 Analytic balance, 95 
 Analyzer, 392 
 
 Anode of a voltaic circuit, 432 
 Anvil, the, 50, 382 
 
 Apparatus, advice in the purchase of, 
 74 
 Ventzke's, 395 
 Beindorfi^'s, 187 
 dealers in and manufactur- 
 ers of, 468 
 Aqueous fusion, 192 
 Areometer, 116, 120 
 
 Nicholson's, 119 
 Argand burner for gas, 59 
 Assaying, 220 
 Assay furnace, 155 
 Astatic galvanometer, 451 
 
 Bags, gas, 216 
 
 Balance room, 34 
 
 table, 34 
 
 platform, 61 
 
 laboratory, 84 
 
 requisite conditions 
 of, 86 
 
 the mint, 88 
 
 excellence of, 92 
 
 Kater's, 92 
 
 Robinson's, 92 
 
 Berlin, 95 
 
 Tralle's, 96 
 
 preservation of, 98 
 
 hydrostatic, 112 
 
 of torsion, 424 
 Basins, supports for, 158 
 Baths, 179 
 
 construction of, 180 
 heating by, 180 
 advantages of, 180 
 evaporation over, 326 
 desiccation by means of, 335 
 heated by gas, 39, 56 
 sand, 37, 39, 56, 151, 186 
 steam, 42, 181 
 water, 182, 183 
 saline, 184 
 metallic, 185 
 oil, 185 
 mercury, 185 
 filter, 358 
 Battery, electrical, 417 
 
 WoUaston's, 432 
 
 Daniell's, 435 
 
 constant, 434 
 
 Smee's, 436 
 
 Grove's, 437 
 
 Bunsen's, 438 
 
 Bird's, 439 
 
 made of blue pots, 439 
 
 mode of connecting, 439 
 
472 
 
 INDEX. 
 
 Bee-hive shelf, 268 
 BeindorfF's apparatus, 187 
 Bell glasses, 266 
 
 graduated, 109, 266 
 capped, 266 
 Bench, work, 50 
 Bennet's electrometer, 421 
 Bird's battery, 439 
 Binding screws for connecting batteries, 
 
 439 
 Berzelius's lamp, 54 
 Black varnish, 58 
 board, 63 
 
 lead crucibles, 194 
 flux, 207 
 Black's blowpipe, 372 
 Bladders, cleansed, 271 
 
 filled with gas, 271 
 Blast furnace, 54, 1 54 
 
 Sefstrom's, 155 
 Aikin's, 155 
 Blowing, glass, 456 
 
 Blowpipe table, blast, 54, 58, 155, 168 
 mouth, 58, 388 
 manipulation, 367 
 use and construction of, 368 
 Gahn's, 370 
 Wollaston's, 369 
 Mitscherlich's, 371 
 Black's, 372 
 economical, 372 
 lamp and appliances, 373 
 flame and blast, 374, 376 
 mode of holding, 376 
 detection of volatile sub- 
 stances by means of, 379 
 instruments for analysis by, 
 
 380 
 test series, 390 
 compound, 171, 263 
 
 fusion by, 201 
 Blue pots, 194 
 Boiling, 149, 307 
 
 by steam, 41, 43, 312, 321 
 in tubes, 307 
 
 beaker glasses, 310 
 flasks, 310 
 capsules, 311 
 vats, Duvoir's, 321 
 points of saturated solutions, 
 184 
 Books, preservation of, 32, 33 
 
 for recording analyses, 53 
 laboratory, 73 
 Borer, charcoal, 381 
 
 Bottles, cleansing of, 49 
 
 glass, Bohemian, 64 
 green, 64 
 
 labelled, 66 
 
 removal of corks from, 68 
 
 test, 68 
 
 for table use, 72 
 
 specific gravity, 115, 117 
 
 Wolffe's, 258 
 
 spritz, 356 
 
 washing, 357 
 Buckets, 51 
 
 Burner, Argand gas, 59 
 Bulb rests, 178 
 Bulbs, glass, blown. 463 
 Bunsen's battery, 438 
 
 Cadet's mode of solution, 319 
 Calcination, 149, 210 
 Calcining furnace, ir3 
 Calorimotor, Hare's, 447 
 Cambridge lamp, 166 
 Camphor, pulverization of, 84 
 Capsules, 311 
 
 Carbonic oxide, reduction by, 218 
 Case, test, 68 
 Cements, 276 
 
 for labels, 279 
 Centigrade thermometer, 139 
 Centre table, 56 
 Chamber, drying, 35 
 Charcoal, repository of, 51 
 
 as fuel for furnaces, 154, 157 
 
 reduction by, 213 
 
 borer, 381 
 
 ignited by galvanism, 445 
 
 prepared for galvanic expe- 
 riments, 446 
 Chemicals, requisite stock of, 72 
 Chemical reaction, crystallization by, 
 
 332 
 Chemist, working costume of the, 72 
 Chest, tool, 50 
 Chimney lamp, 54 
 Chlorcalcium tube, 341 
 Circuit, simple galvanic, 431 
 Circular polarization, 393 
 Clay crucibles, 193 
 Cleansing apparatus, 50 
 
 of glass, 48 
 CleanUness enjoined, 72 
 
INDEX. 
 
 473 
 
 Clerget's method of analysis, 403 
 
 Cloths, filtering, 359 
 
 Coal cylinders for batteries, 439 
 
 Cohobation, 250 
 
 Coke, 51 
 
 as fuel for furnaces, 157 
 for cutting glass, 459 
 Coking, 211 
 
 Collection of gases, 254 
 Compound blowpipe, 171, 263 
 Condenser, Liebigs, 239 
 Connection of batteries, 439 
 Construction of baths, 180 
 
 formulae, 452 
 Contents, table of, vii 
 Contusion, 75 
 Cooler, 234 
 Cooling mixtures, 190 
 Corks, repository for, 57 
 borer, 57, 466 
 removed from bottles, 69 
 softened, 466 
 
 rendered impermeable, 466 
 perforated, 467 
 India rubber, 467 
 Costume, laboratory, 72 
 Coulomb's electrometer, 424 
 Crown of cups, 431 
 Crucibles, 50 
 
 manufacture of, 197 
 
 supports for, 158 
 
 jacket, 164 
 
 position in furnace, 154 
 
 heated over blowpipe flame, 
 
 170 
 directions for heating, 54, 1 98 
 clay, 193 
 Hessian, 1 93 
 London, 193 
 French, 193 
 black lead, 194 
 porcelain, 194 
 metallic, 195 
 iron, 195 
 silver, 196 
 
 platinum, 53, 196, 197 
 sublimation in, 228 
 Crystallization, 149, 328 
 
 by fusion, 328 
 by sublimation, 328 
 from solution, 329 
 by chemical reaction, 
 332 
 Crystals, purification of, 331 
 Cupboards, 62 
 
 31 
 
 Cupel furnace, 156 
 
 Cupellation, 149, 222 
 
 Cupels, 220 
 
 Curtains, rendered fire proof, 29, 62 
 
 Cushion, for electrical machine, 411 
 
 Cylinder electrical machine, 409, 411 
 
 Cyhnders, fire, 44 
 
 Daniel's pyrometer, 137 
 
 constant battery, 434 
 Darcet's digester, 305 
 Dealers in and manufacturers of che- 
 micals and apparatus, 468 
 Decantation, 345 
 
 washing by, 364 
 Decoction, 149, 300 
 Decolorization, 397 
 Decrepitation, 212 
 Deflagration, 149,213 
 Density of bodies, determination of, 
 
 112 
 Desiccation, 149, 333 
 
 by means of baths, 335 
 in air chambers, 334 
 
 vacuo, 338 
 of gases, 340 
 liquids, 339 
 solids, 333 
 
 easily alterable sub- 
 stances, 7, 336 
 Desk, drawing, 3 1 
 
 writing, 30 
 Deville's gasometer, 265 
 Diaphragms for galvanic batteries, 435 
 Difi"erential thermometer, 142 
 Digester, D'Arcet's, 305 
 
 Mohr, 306 
 Digestion, 54, 149, 153, 301 
 
 in beaker glasses, 302 
 
 flasks, 303 
 under pressure, 304 
 Discharger, electrical, 419 
 Displacement, 313 
 
 solution by, 314 
 Distillation, 44, 149, 225 
 
 destructive, 232 
 dry, 274, 232 
 gaseous, 250 
 in tubes, 240 
 
 retorts, 235, 238 
 in vacuo, 273 
 liquid, 232, 245, 249 
 
474 
 
 INDEX. 
 
 Distillation, solid, 232 
 
 the cooler, 234 
 micro-chemical, 240 
 rules for, 243, 244 
 
 Division, 84 to 75 
 
 by slicing, 75 
 contusion, 76 
 chemical means, 83 
 elutriation, 82 
 granulation, 83 
 levigation, 82 
 porphyrization, 79 
 rasping, 75 
 trituration, 79 
 intermedia, 83 
 
 Donovan's filter, 362 
 
 Draining racks, 48 
 
 Dropping tubes,^106 
 
 Drummond light, 174 
 
 Drying chamber, 35 
 tubes, 340 
 
 Duvoir's boiling vats, 321 
 
 Dye-woods, exhaustion of, 43 
 
 Earthen virare retorts, 243 
 Ebullition, 307 , , 
 
 Economical blowpipes, 372 
 Edulcoration, 365, 384 
 Efflorescence, 333 
 Electrical spark in eudiometry, 428 
 machine, cylinder, 409 
 
 plate, 413 
 battery, 47 
 Electricity, 409 
 
 detection and measurement 
 of, 421 
 Electro-chemical decomposition, 441 
 
 magnetic multiplier, 450 
 Electrolysis, 441 
 Electrolytes, 441 
 
 Electrometer, Henley's quadrant, 420 
 Bennet's, 421 
 opposite electricities in- 
 dicated by, 424 
 induction of electricity in, 
 
 423 
 condensing, 424 
 Coulombs, 424 
 Electrophorus, 420 
 Electroscope, 382 
 Electrotype, 436 
 Elutriation, 82 
 
 Etching upon glass, 66 
 
 Eudiometer tubes, graduation of, 132 
 
 Hare's, 446 
 Eudiometry, 426 
 Evaporating furnace, 153 
 
 vessels, 323 
 Evaporation, 149, 153, 322 
 
 spontaneous, 323 
 
 in vacuo, 324 
 
 by heat in open air, 325 
 
 over baths, 326 
 
 by steam, 326 
 heated air, 326 
 
 over naked fire, 327 
 
 Fahrenheit's thermometer, 13j9 
 Faraday's voltameter, 443 
 
 ■ tube for collection of gases 
 . in efectrolysis, 443 
 Filter baths, ^58 
 
 ■* papers, Kent's, 52 
 '^ stands, 177 
 Filtering apparatus, 354 
 
 directions for, 355 
 paper, 52, 349 
 
 ' German, 349 
 Swedf^h, 349 
 repository for, 57 
 • clotbs, 58 
 Filters, folded, 353 
 
 introduced into funnels, 353 
 plain, 352 
 plaited, 352 
 ignition of, 201, 55 
 desiccation of, 35 
 washing of, 374 
 Donovan's, 363 
 Riouffe's, 363 
 Jennison's, 47 
 Filtration, 345, 348 
 
 promoted by warmth, 358 
 hot, arrangement for, 35 
 through paper, 348 ^ 
 cloths, 359 
 pulverulent matter, 
 361 
 of acids, 361 
 
 corrosive liquids, 361 
 volatile liquids, 363 * 
 
 Fire cylinder, 44 
 
 lute, vessels coated with, 278 
 Flame, blowpipe, 374 
 
INDEX. 
 
 475 
 
 Flasks, 310 
 
 Florence, 253 
 specific gravity, 115, 117 
 supports for, 158 
 sublimation in, 227 
 solution in, 310 
 Flexible tubes, 216 
 Florence flasks, 253 
 Florentine receivers, 249 
 Flowers, distillation of, 45 
 
 by sublimation, 228 
 Fluids, specific gravity of, determined, 
 117 
 by flasks, 118 
 hydrometers, 119 
 measuring of, 128 
 Flux, black, and its equivalent, 217 
 Fluxes, metallic, 209 
 
 non-metallic, 206, 204 
 ignition with, 203 
 Fluxing, 149, 203 
 Formulae, construction of, 452 
 Freezing mixtures, 189, 191 
 French crucibles, 193 
 Fuel, 168 
 
 Funnel tubes, manufacture of, 465 
 Furmels, filtering, 350 
 
 separatory, 350 
 ribbed, 350 
 
 glass, 350 ^X 
 
 porcelain, 351 - ^<^ ''• 
 stone, 351 " "^ 
 
 supports for, 354 
 filters, placed in, 353 
 Furnaces, room, its arrangement, 34 
 
 laboratory, its construction, 
 
 35,38 
 Luhme's (portable), 39, 150 
 Kent's (portable), 39, 152 
 Still, 44 
 'blast, 54, 154 
 tongs, 159 
 stationary, 149 
 universal, 150, 152 
 table, 150 
 evaporating, 153 
 calcining, 153 
 reverberatory, 153 
 assay, 155 
 Sefstrom's blast, 155 
 Aikin's blast, 155 
 cupel, 156 
 Liebig's, 157 
 furniture, 158 
 
 Furnaces, management of, 157 
 Fusion, 149, 171, 192 
 igneous, 192 
 aqueous, 192 
 
 of bodies inalterable by air or 
 heat, 199 
 
 alterable by heat, 200 
 alterable in air, 200 
 of diflficultly fusible substances, 
 
 201 
 by hydrogen blowpipe, 201 
 crystallization by, 328 
 
 Gahn's blowpipe, 370 
 Gallows' screw, 54 
 Galvanic currents, direction of, 452 
 light and heat, 445 
 battery, Wollaston's, 432 
 Daniell's, 434 
 Smee's, 436 
 Grove's, 437 
 Bunsen's, 438 
 Galvanism, 431 
 
 precipitation by, 344 
 applied to eudiometry, 446 
 decomposition of 
 fluids, 443 
 ' heat and light produced by, 
 444 
 Galvanometer, 449 
 
 astatic, 451 
 Gas, generation and absorption of, 172, 
 173, 257 
 illuminating, 168 
 
 from grease, 169 
 mode of burning, 
 
 55 
 heatmg by, 39, 54 
 lamp, 54, 168 
 
 for laboratory operations, 55 
 bags, 216 
 jars, 266 
 receivers, 266 
 
 reservoir, self-regulating, 173 
 collected over water, 268 
 air, 270 
 mercury, 270 
 transfer into bell-glasses, 271 
 bladders, 271 
 from gasometers, 263 
 
476 
 
 INDEX. 
 
 Gaseous distillation, 232 
 Gases, correction of, for pressure, 1 1 0, 
 272 
 
 temperature, 
 110, 292 
 solubility of tested, 282 
 solution, 286 
 liquefaction, 286 
 solidification, 286 
 conducted into gasometers, 262 
 weighing of, 108 
 measurement of, 133 
 specific gravity of, determined, 
 
 122 
 distillation of, 250 
 
 tube apparatus 
 for, 252 
 collection of, 254 
 desiccation of, 340 
 (Gasometers, 261 
 
 filled, 262 
 
 gases, transferred from, 
 
 263 
 Pepy's, 261 
 mercurial, 263 
 Deville's, 265 
 Generator, steam, 39 
 Glass, etching upon, 66 
 tubes, 219 
 retorts, 236 
 funnels, 350 
 
 vessels, exhausted of air, 109 
 Glass-blowing, 455 
 
 tables for, 457 
 lamp for, 457 
 implements for, 458 
 position and manage- 
 ment of the tube over 
 the flame, 459 
 cutting, 459, 461 
 tubes cemented, 460 
 bent, 460 
 drawn out, 461 
 closed, 462 
 
 bulbs blown, 463, 464 
 tubes, edges of, widened and 
 smoothed, 459 
 Glasses, cleansing of, 49, 66 
 repository for, 62 
 Bell, 266 
 Gold, pulverization of, 84 
 Graduates, 129 
 
 Graduation of vessels, 128, 131 
 Granulation, 83, 330 
 
 Gravimeter, Nicholson's, 119, 122 
 Grove's battery, 437 
 
 H 
 
 Hare's compound blowpipe, 171 
 sliding rod eudiometer, 446 
 calorimotor, 447 
 Heat, sources and management of, 149 
 and light produced by galvanism, 
 444 
 Heating by baths, 180 
 Henley's quadrant electrometer, 420 
 Henry's apparatus for hydrosublima- 
 
 tion, 230 
 Hessian crucibles, 193 
 Hoods for furnaces, 26, 39 
 
 retorts, 244 
 Horsford's lamp, 166 
 Hydrogen, generation of, 173 
 reduction by, 213 
 Hydrometers, 58, 119, 120 
 
 mode of using, 121 
 Hydrometric degrees, table of, 121 
 
 I& J 
 
 -Jacket, crucible, 164 
 Jars, gas, 266 
 
 Ley den, 416 
 Jennison's filter, 47 
 Igneous fusion, 1 92 
 Ignition, 54, 149, 201 
 of filters, 201 
 of bodies in vapors, 202 
 with fluxes, 203 
 for determination of hygro- 
 scopic matter, 202 
 Incineration, 149, 211 
 Indelible labels, 66 
 Index rerum, 69 
 
 India rubber apparatus, repository for, 
 57 
 tubes, use and manufac- 
 ture of, 215 
 gas bags, 216 
 door springs, 29 
 Infusion, 300 
 Ink for labels, 69 
 
 Intensity of galvanic fluid, 433, 435, 
 444 
 
INDEX, 
 
 m 
 
 Iron crucibles, 195 
 retorts, 218 
 tubes, 241 
 
 Kater's balance, 92 
 Kathode of a voltaic circuit, 432 
 Kennedy's air-pump, 60 
 Kent's furnace, 39, 152 
 Ker's tube, 135 
 
 Kettle for constant supply of hot water, 
 66 
 
 Labelling, importance and necessity of, 
 
 65 
 Labels, 65 
 
 rendered indelible, 65 
 La Rue & Co.'s, 66 
 etched, 66 
 ink for, 69 
 cement for, 279 
 Laboratory, construction of, 27, 28, 29 
 arrangement of, 25, 30 
 lighting of, 26 
 ventilation of, 26 
 costume, 72 
 book, 73 
 
 operations, record of, 53 
 portable (Beindorff's), 186 
 Lamp, spirit, 54, 160 
 
 Berzelius's, 54, 153 
 gas, 54, 168 
 glass, 160 
 Rose's, 166 
 Russian, 167 
 Horsford's, 166 
 Cambridge, 166 
 Luhme's, 165 
 
 blowpipe and appliances, 373 
 glass-blower's, 457 
 oil, 162 
 
 tongs, 161, 170 
 supports, 164 
 Lamps, heating over, 160 
 
 tubes heated by, 162 
 Levigation, 82 
 Leyden jar, 416 
 
 residual charge of the, 419 
 Liebig's furnace, 157 
 
 bulbed receiver, 256 
 
 31* 
 
 Light, 26 
 
 sky, disadvantages of, 26 
 Drummond, 174 
 analysis by polarization of, 391 
 Liquefaction of gases, 286 
 Liquid distillation, 232 
 Liquids, slow evaporation of, 35 
 weighing of, 106 
 transfer of, in dropping tubes, 
 
 106 
 distillation of, 245, 247 
 
 volatile, 249 
 solution of, 286 
 filtration of corrosive, 361 
 
 volatile, 361 
 desiccation of, 339 
 Local action upon the zinc of batteries, 
 
 433 
 London crucibles, 193 
 Low temperatures, mode of producing, 
 
 188 
 Luhme's furnace ("mwiWsoZ"), 39, 150 
 
 lamp, 165 
 Lute, vessels coated with fire, 278 
 Lutes, 274 
 
 application of, 279 
 
 M 
 
 Maceration, 299 
 Magnet, 383 
 Maneigement of heat, 149 
 
 furnaces, 157 
 Manipulation, blowpipe, 367 
 Marsh's tube apparatus, 253 
 Mastich, Hamelin's, 27 
 Measurement of temperature, 136 
 Measures, 129 
 
 of capacity, value in inches, 
 133 
 Measuring of fluids, 128 
 gases, 133 
 Melloni's thermomultiplicator, 142 
 Mercury bath, 185 
 trough, 269 
 gasometer, 263 
 cups for connecting batteries, 
 440 
 Metals, division of, 77, 83 
 
 fusing point of, 138 
 Metallic crucibles, 195 
 tubes, 218 
 batlis, 185 
 
478 
 
 INDEX. 
 
 Micro-chemical distillation, 240 
 Microscope, 381 
 Minerals, preservation of, 30 
 cases, 31 
 
 for analysis, 78, 82 
 Mitscherlich's blowpipe, 371 
 Mixtures, freezing, 189 
 Mohr's digester, 306 
 Mortar iron, 51, 76 
 
 steel, 78 
 
 agate, 79, 382 
 
 porcelain, 79 
 
 wedgewood, 79 
 
 glass, 80 
 Mother waters, treatment of, 330 
 Muffles, 222 
 
 Taylor's, 223 
 
 N 
 
 Neutralization, 280 
 Nicholson's gravimeter, 117 
 Nobili's astatic galvanometer, 451 
 
 Office, arrangement of, 30 
 Oil bath, 185 
 
 lamp, 162 
 
 olive, 162 
 Operating room, the, 51 
 table, the, 52 
 Ores, pulverization of, 77 
 Oxygen, apparatus for generation of, 
 
 172 
 Oxy-hydrogen blowpipe, 174 
 
 Paper filters, 349 
 
 filtering, German, 349 
 Swedish, 349 
 repository for, 57 
 
 Pepy's gasometer, 261 
 
 Phosphorus, pulverization of, 83 
 
 Pincettes, 380 
 
 Pipettes, 107 
 
 Plain filters, 352 
 
 Plaited filters, 352 
 
 Plate electrical machine, 413 
 
 Platinum crucibles, 196, 197 
 tubes, 219 
 
 Platinum retorts, 241 
 
 foil in batteries, 439 
 
 used for electrodes, 441,442, 
 
 444 
 wires ignited by galvanbm, 
 446 
 Pliers, 381 
 
 Plumbago crucibles, battery of, 439 
 Pneumatic pump, 60 
 
 syringe, 60, 267 
 troughs, 265 
 Polarization of light, analysis by, 391 
 Polarizer, 392 
 
 Poles of a simple galvanic circuit, 431 
 a compound galvanic circuit, 
 
 432 
 platinum for electrolysis, 441, 
 442 
 Porcelain retorts, 242 
 tubes, 218 
 crucibles, 194 
 funnels, 351 
 Porphyrization, 79 
 Portable laboratory, 186 
 Pots, blue, 194 
 Pouring, 346, 356 
 Precipitates, desiccation of, 35 
 
 washing of, 364 
 Precipitation, 342 
 
 directions for, 343 
 by galvanism, 344 
 vessels for, 343 
 Press, 320 
 
 Pressure, digestion under, 304 
 Prisms, Nicholson's, 392 
 Pulverization, 77 
 
 Purchase of apparatus, advice as to, 74 
 Purification of crystals, 331 
 Pyrometer, 136 
 
 Daniell's, 136 
 Pyroxylic spirit, 160, 168 
 
 Q 
 
 Quantity of the galvanic fluid, 433, 441 , 
 444 
 
 R 
 
 Rack, test, the, 179 
 
 tube, 62 ' 
 Reaction, chemical, crystallization by, 
 332 
 
INDEX. 
 
 479 
 
 Reagents, the series of, 69 
 
 purity of, 72 
 Reaumur's thermometer, 139 
 Receivers, 238, 239, 246 
 
 bulbed, Liebig's, 256 
 gas, 266 
 Florentine, 249 
 Record of analyses, 73 
 Rectification, 250 
 Reduction, 149 
 
 by chemical means, 83 
 charcoal, 213 
 hydrogen, 215 
 carbonic oxide, 218 
 apparatus, 215 
 tubes, 179, 218 
 Refrigerant, the, 44 
 Rerum, index, 73 
 Reservoir, self-regulating, 173 
 Rests, tube and bulb, 178 
 Retorts, glass, 53, 236 
 porcelain, 242 
 earthenware, 243 
 stoneware, 243 
 iron, 241, 254 
 platinum, 241 
 mode of filling, 247 
 adapted to tubes and receivers, 
 
 247 
 sublimation in, 228 
 distillation in, 235, 238 
 selection of, 236 
 repository of, 62 
 supports for, 176, 177 
 Reverberatory furnace, 153 
 Rioufie's filter, 363 
 Roasting, 149, 211 
 
 in tubes, 218 
 Robinson's balance, 92 
 Room balance, arrangement of, 34 
 furnace, arrangement of, 34 
 operating, arrangement of, 5 1 
 Roots, distillation of, 45 
 Rose's lamp, 166 
 Rubber of electrical machine, 411 
 
 amalgam 
 for, 4 12 
 Russian lamp, 167 
 
 S 
 
 Saccharimeter, Soleil's, 399 
 Saccharine substances, analysis of, 391 
 Safety tubes, 259 
 
 Saline baths, 184 
 
 Salts, table of the solubility of, 287 
 Sand, 39, 57, 153, 185 
 baths, 38, 39 
 • table, 56 
 temporary, 186 
 Saturated solutions, boiling points of, 
 -184 
 
 Saturation, 280, 285 
 Schweigger's galvanometer, 450 
 Screw, gallows', 54 
 Sefstrom's blast furnace, 155 
 Separatory funnels, 350 
 Series, the test, 69 
 Sieves, 80 
 Sifting, 81 
 
 Silica, pulverization of, 84 
 Silicious stones, pulverization of, 77 
 Silver, pulverization of, 84 
 crucibles, 196 
 
 platinized, for Smee's battery, 
 436 
 Sink, the, 46 
 
 Skylight, disadvantages of, 26 
 Slicing, 75 
 Smee's battery, 436 
 Soleil's saccharimeter, 398 
 Solid distillation, 232 
 Solidification of gases, 286 
 Solids, weighing of, 104 
 
 specific gravity, determination 
 
 of, 112 
 solution of, 283 
 
 influenced by tem- 
 perature, 284 
 modes of effecting, 285 
 desiccation of, 333 
 Solubility, mode of testing, 281 
 
 of salts, table, 287 
 Solution, 149 
 
 simple, 280 
 
 chemico-mechanical, 280 
 saturated, 280 
 of solids, 283 
 liquids, 286 
 gases, 286 
 by boiling, 286 
 steam, 286 
 displacement, 313 
 in close vessels, 317 
 under pressure of steam, 32 . 
 Cadet's mode of, 319 
 means of facilitating, 282 
 crystallization from, 329 
 Solutions, decolorization of, 397 
 
480 
 
 INDEX. 
 
 Solutions, saturated, boiling points of, 
 
 184 
 Sources of heat, 149 
 Spatulas, 53 
 
 Specific gravity, determination of, 112 
 of solids, 112 
 fluids, 117 
 gases, 122 
 vapors, 126 
 by means of the bal- 
 ance, 112 
 by means of the flask, 
 
 115, 117 
 by means of the hy- 
 drometers, 119 
 by means of the gra- 
 
 vimeter, 116 
 bottles, 115 
 Spirit lamp, 54, 161 
 pyroxylic, 168 
 Spontaneous evaporation, 323 
 Spritz bottles, 356, 365, 384 
 Stands, filter, 177 
 Steam generator, the, 39, 41 
 baths, 42, 181 
 solution by, 312 
 boiling by, 321 
 evaporation by, 326 
 Stench trap, 47 
 Still, 43, 233 
 
 furnace for, 44 
 Stock for laboratory, 72 
 Stoneware retorts, 243 
 Strainers, 359 
 
 Straining through cloths, 360 
 Sublimation, 149 
 
 crystallization by, 328 
 implements of, 225 
 in tubes, 226 
 flasks, 227 
 retorts, 228 
 crucibles, 228 
 shallow vessels, 229 
 Ure's apparatus, 230 
 Henry's apparatus, 230 
 Substances, division of, 75 
 Sugar, analysis of, bv polarization of 
 
 light, 391 
 Sulphate of copper used in batteries, 
 
 435 
 Sulphur, pulverization of, 84 
 Supports for tall vessels, 106 
 funnels, 354 
 crucibles, 158 
 flasks and basins, 158 
 
 Supports, lamp, 164 
 
 Gray Lussac's, 176 
 
 Gahn's, 177 
 
 universal, 176 
 
 blowpipe operations, 377 
 Sjrphon eudiometer, 429 
 Syphons, 349 
 Syringe, 108 
 
 pneumatic ,267, 358 
 Syrups, filtration of, 362 
 
 Table, balance, 34 
 operating, 52 
 blowpipe, blast, 54, 58, 169, 458 
 
 mouth, 58, 388 
 centre, 56, 57 
 furnace, 150 
 
 of hydrometric degrees, 121 
 thermometrical equivalents, 
 
 144, 149 
 value of measures of capacity 
 in cubic inches, 133 
 for the analysis of saccharine 
 
 substances, 405 
 for glass-blowers, 456 
 of boiling points of saturated 
 solutions, 184 
 solubility of salts, 287, 299 
 Temperature, measurement of, 136 
 
 low, mode of producing, 
 
 188 
 influence of, in efiecting 
 solution, 285 
 Test series, 69 
 
 rack, 53, 179 
 case, 68 
 bottles, 68 
 tubes, 308 
 Thermometers, 58, 136 
 
 Fahrenheit's, 139 
 Centigrade, 139 
 Celsius's, 139 
 Reaumur's, 139 
 differential, 142 
 construction and gra- 
 duation of, 141 
 rules for translating the 
 
 degrees of, 140 
 manner of using, 141 
 Thermo metrograph, 142 
 multiplicator, 142 
 
INDEX. 
 
 481 
 
 Tongs, lamp, 161, 170 
 
 furnace, 159 
 Tools, 50 
 
 Towels, place for, 49, 53 
 Tralle's beam, 96 
 Transfer of gases, 271 
 Trap, bell stench, 47 
 Trituration, 79 
 Trivet, 158 
 
 Troughs, pneumatic, 265 
 water, 266 
 mercury, 269 
 Tube,Ker's, 135 
 rack, 62 
 
 holders, 176, 177 
 rests, 178 
 
 apparatus, for distillation of gases, 
 253 
 Tubes, test, 308 
 
 drying, 340 
 U, 340 
 
 chlorcalcium, 341 
 washing, 367 
 dropping, 106 
 boiling in, 308 
 graduation of, 131 
 flexible, 216 
 India rubber, 216 
 reduction, 219 
 porcelain, 218 
 metallic, 218 
 iron, 218 
 platinum, 219 
 glass, 219 
 sublimation in, 226 
 distillation in, 240 
 heated, 162 
 reduction, 179 
 manufacture of, 465 
 Welter's, 465 
 glass blown, 456 
 cut, 459 
 cemented, 460 
 bent, 460 
 
 closed and drawn out, 461 
 edges of, widened and 
 smoothed, 459 
 
 U 
 
 U tubes, 340 
 Universal furnaces, 150 
 Ure's apparatus for sublimation, 230 
 eudiometer, 429 
 
 Ure's water bath, 181 
 Uses of baths, 180 
 
 Vacuum produced, 324 
 Vacuo, evaporation in, 324 
 desiccation in, 338 
 distillation in, 293 
 Vapors, specific gravity of determined, 
 122 
 
 ignition of bodies in, 202 
 Varnish, black, 58 
 Ventilation, 26, 39 
 Ventzke's apparatus, 395 
 Vessels, coated with fire lute, 278 
 exhausted of air, 109 
 graduated, 130 
 cleansed, 48 
 Volatile liquids, distillation of, 249 
 
 substances, detection of, by 
 blowpipe, 379 
 Voltaic pile, 431 
 Voltameter, Faraday's, 443 
 
 W 
 
 Washing, 363 
 
 bottles, 356, 364, 384 
 
 tubes, 367 
 
 of precipitates and filters, 
 
 365 
 by decantation, 364 
 Water, constant supply of hot, 41, 66 
 for the laboratory, 49 
 bath, 45, 181, 183 
 distilled, 72 
 trough, 266 
 
 gases collected over, 268 
 mother, treatment of, 330 
 Weighing, 102 
 
 directions for, 103 
 double, 104 
 of solids, 104 
 
 hygrometric substances, 
 
 105 
 corrosive substances, 105 
 liquids, 106 
 
 volatUe, 108 
 gases, 108 
 Weights, 98 
 
 metrical or decimal, table of, 
 
482 
 
 INDEX. 
 
 Weights, avoirdupois, 61 
 
 series of, for analytic balance, 
 
 101 
 adjudication of, 100 
 preservation of, 101 
 
 Welter's tube, manufacture of, 465 
 
 Wind furnace, 154 
 
 Wire, for battery purposes, 440 
 
 WolfFe's bottles, 258 
 
 Wollaston"s blowpipe, 369 
 battery, 432 
 
 Work bench, 50 
 Writing desk, 32 
 
 Zinc, granulation of, 83 
 
 local action on, in batteries, 433 
 prevented by amal- 
 gamation, 434 
 
 THE END. 
 
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