UC-NRLF 
 
 B M SOD fiflD 
 
 
 RY OF P01 TRY 
 
 ION 
 
LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 ClMS 
 
THE 
 
 CHEMISTRY OF POTTERY, 
 
 &e., &e. 
 
 yap re KaKrj TTfXtrai, KOV<J>Y) fjitv aclpai 
 yuaA, apyaXer) Se ^>epeiV, ^aAcTrr; 8' aTro^eSai. HESIOD, 
 
 Do this yet shun ill fame at first with ease 
 Borne, because light as air, but soon man finds 
 Its weight too great to bear, or yet shake off. 
 
THE 
 
 CHEMISTRY 
 
 OF THE SEVERAL 
 
 NATURAL AND ARTIFICIAL 
 
 HETEROGENEOUS COMPOUNDS, 
 
 USED IN MANUFACTURING 
 
 PORCELAIN, GLASS AND POTTERY. 
 
 BY SIMEON SHAW, LL.D. 
 
 AUTHOR OF " NATURE; DISPLAYED," &c., &c. 
 
 " QUID VERUM ATQUE UTILITAS, CURO ET ROGO, ET OMN1S IN HOC SUM ; CONDO, ET COMPONO, 
 QU^K MOX DEPROMERE POSSIM." HORACE. 
 
 " IN WHAT IS TRUE AND USEFUL, MY WHOLE CARE AND ENQUIRY, I AM SOLELY OCCUPIED, 
 ALWAYS COLLECTING AND DISPOSING, SO THAT THE STORE CAN AT ANY TIME BE IMMEDIATELY 
 DRAWN FORTH." 
 
 ORIGINALLY PUBLISHED BY W. LEWIS AMD SON, FINCH-LANE, LONDON, 
 
 IN 1837. 
 
 ILonfcon : 
 
 REISSUED IN ITS ORIGINAL FORM BY 
 SCOTT, GEEENWOOD AND CO. 
 
 of +4 0e (pottery <0c3ffe + ++ 
 19 LUDGATE HILL, E.C. 
 
 1900. 
 
B-DI, 
 
 r-il*. 
 
 "ENGLISHMEN A RACE NOT SLOW AND DULL, BUT OF A QUICK, INGENIOUS, AND DISCERN- 
 ING SPIRIT; ACUTE TO> INVENT, SUBTLE AND SINEWY TO- DISCOURSE; NOT BENEATH THIC 
 REACH OF ANY POINT, THE HIGHEST THAT HUMAN CAPACITY CAN SOAR TO. WHAT WANTS THERE 
 TO SUCH A TOWARDLY AND* PROLIFIC STOCK, BUT WISE AND FAITHFUL LABOURERS, TO MAKE A 
 
 KNOWING PEOPLE, A NATION OF PROPHETS, OF SAGES, AND OF WORTHIES?" MlLTON. 
 
DEDICATORY PREFACE; 
 
 TO THE SUBSCRIBERS. 
 
 HIS GKACE THE DUKE OF SUTHERLAND, 
 
 Stafford House, London (2 C.). 
 
 THE BIGHT HONOURABLE EARL FITZWILLIAM, 
 
 Grosvenor Place, London ("2 C.). 
 
 JOHN DAVENPORT, ESQ., M.P West-wood. 
 
 THOMAS MACKENZIE, M.D Newcastle, U. L. 
 
 HUGH HENSHALL WILLIAMSON, ESQ .Greenway Bank. 
 
 JOSIAH SPODE, ESQ The Mount. 
 
 WILLIAM TAYLOR COPELAND, ALD. & M.P. ..London. 
 
 THOMAS THOMSON, M.D., F.R.S.L. & E Glasgow." 
 
 ROBERT WILLIAMSON, ESQ Ramsdell. 
 
 SPENCER ROGERS, ESQ Watlands. 
 
 JOHN AYSHFORD WISE, ESQ Clayton. 
 
 Messrs. WILLIAM DAVENPORT & Co., Manufac- J 
 
 turers of China to His Majesty and the ,-Lonqport. 
 
 Royal Family (2 C.) I 
 
 Mr. WILLIAM WAIN WRIGHT POTTS, Patentee) , 
 
 of Continuous Printing and in Colours ..y 
 SPENSER GARRETT, China and Earthenware \ . , , , 
 
 Manufacturer / Stoke-upon-Trent. 
 
 WILLIAM MACHIN (8 C.) Bursbm. 
 
 SAMUEL ALLCOCK ditto 
 
 RICHARD DANIEL (2 C.) Stoke. ' 
 
 THOMAS GOODFELLOW Timsta.ll. 
 
 BENJAMIN SINGLETON BKOUGH Longton. 
 
 WILLIAM BROOKES Burslem. 
 
 THOMAS HUXLEY Tunstall 
 
 WILLIAM BOURNE Bur stem. 
 
 SAMUEL BOURNE ditto 
 
 CHARLES COCKSON Cobridge. 
 
 FRANCIS EMERY ditto 
 
 Messrs. ENOCH WOOD & SONS (2 C.) Burslem. 
 
 STEPHEN HUGHES & BROTHERS . ... . . ditto 
 
 RALPH HALL & SON . ..Tunstall. 
 
 128999 
 
VI DEDICATORY PREFACE. 
 
 Mr. JOHN GERHARD, Colour Manufacturer Hanley. 
 
 W. H. PANKHURST Sketton. 
 
 JOSEPH TWIGG Hurxlein. 
 
 GEORGE SPARKES . . . iMne-Kml. 
 
 JOHN BRIDGWOOD ditto 
 
 CHARLES JAMES MASON, Patentee of Iron- I ,, . 
 
 stone China \Fenton. 
 
 WILLIAM ADAMS, Earthenware Manufacturer. . Tnnxttill. 
 EDWARD ADAMS, China and Earthenware I .,. , 
 
 Manufacturer I ' 
 
 BENJAMIN HARRIS, China Manufacturer . . . . Longton. 
 
 JOHN HANCOCK Tun stall. 
 
 JOSEPH HEATH ditto 
 
 JOHN BOYLE Stoke. 
 
 THOMAS ROWLEY Tintstall. 
 
 GEORGE HOOD ditto 
 
 EDWARD CHALLINOR ditto 
 
 HENRY MEIR ditto 
 
 GEORGE BRUMMITT ditto 
 
 Messrs. PODMORE, WALKER, BURROWS & Co. ditto 
 
 SAMUEL PETTY & SON Leeds. 
 
 JOSEPH TWIGG & BROTHERS Rawmarxh. 
 
 THOMAS TAYLOR & Co ditto 
 
 ROBERT ALEXANDER KIDSTON & Co. . . Glasgow. 
 
 BELL & SMITH Wliitehaven. 
 
 POUNTNEY & GOULDNEY Bristol. 
 
 SAMUEL MAYER, MAWDESLEY & Co. ..Burslem. 
 
 W. SMITH, JOHN WALLEY & Co Stockton. 
 
 THOMAS & JOHN CAREY Longton. ' 
 
 J. & J. GOODWINS ditto 
 
 B'EARDMORE & BIRKS ditto 
 
 Mrs. ELIZABETH HAWLEY Rawmarsh. 
 
 Mr. FELIX PRATT Fenton. 
 
 JAMES KELSALL, Colour Manufacturer Burslem. 
 
 THOMAS HULME ditto 
 
 JOHN IRVIN HOLDEN ditto 
 
 JOHN RILEY MARSH Law-End. 
 
 JOHN BAKER Fenton. 
 
 JOHN MARTIN, Clay and Stone Merchant St. Anstlc. 
 
 RICHARD YELLAND ditto 
 
 J. & J. NIXON, Earthenware Manufacturers ...... C abridge. 
 
 CHARLES ME1GH Hanley. 
 
 GEORGE JOHNSON ditto 
 
 SAMUEL KEELING ditto 
 
 JOSEPH POULSON She-lton. 
 
 STEPHEN CHAPPELL (2 C.) Leeds. 
 
 GEORGE GORDON . . Preston Pans. 
 
 Messrs. THOMAS DAWSON & Co... . . Sunder land. 
 
DEDICATORY PREFACE. Vll 
 
 Messrs. BARKER, SUTTON & TILL Bur stem. 
 
 SAMUEL & JOHN BURTON Hanlcy. 
 
 WALTER CHAMBERLAIN & Co. Porcelain ) 
 
 Manufacturers to His Majesty and the - Worcester. 
 Royal Family ) 
 
 JOHN ROSE & Co Coalport. 
 
 Mr. WILLIAM COOPER, Patent Glass Manufacturer l 
 
 to the King I 
 
 JOHN BIDDLE, Glass Manufacturer Birmingham. 
 
 BENJAMIN RICHARDSON Wordsley. 
 
 SAMUEL SHAKESPEAR Birmingham. 
 
 EDWARD LACKLAND Leith. 
 
 JOSEPH STEVENS Dudley. 
 
 WILLIAM LEIGH ditto 
 
 WILLIAM HODGETTS Wordsley. 
 
 JOHN SHEPHERD Coalnbourn Brook. 
 
 HENRY JACKSON Tutbunj. 
 
 THOMAS GOULTHARD (Jateshead. 
 
 HENRY CUTLER ..Ecck'ston. 
 
 WILLIAM DODD, Glass-Stainer Shrewsbury. 
 
 Messrs. M. & W. GRAZEBROOK, Glass Manufacturers Audnum. 
 
 SILVERS & STEVENS Brierley Hill. 
 
 WESTWOODS & MOORES ditto 
 
 CHANCE BROTHERS Birmingham. 
 
 MORGAN, ROLLASON & Co ditto 
 
 H. RICKETTS & Co Bristol. 
 
 MOLINEUX, WEBB, ELLIS & Co. (3 C.) . . Manchester. 
 
 SHEPHERD & WEBB (2 C.) Wordsle.y. 
 
 BADGER BROTHERS & Co ditto 
 
 JOSHUA WALKER, PARKER & Co.,).,,, 
 Lead Manufacturers J ' 
 
 RAY & TIDES WELL, China Manufacturers. .Longton. 
 
 Mr. JOHN HILDITCH Lane-End. 
 
 SAMPSON BRIDGWOOD Longton. 
 
 MICHAEL TUNNICLIFFE Tunstall. 
 
 DANIEL EDGE Burslem. 
 
 RICHARD BOOTH Shelton. 
 
 GEORGE GRAINGER Worcester. 
 
 JAMES RIDDELL Longton. 
 
 JOHN CARTER, China Enameller Hanley. 
 
 JOHN BETTS SHARPS London. 
 
 JOHN FORD Brownhilh. 
 
 JOHN DAWSON London. 
 
 RALPH KEELING, Jun Shelton. 
 
 THOMAS WOOD , Swansea. 
 
 RICHARD DAVIES ditto 
 
 MARTIN BEVAN & Co ditto 
 
 J. S. HINCK*LEY ditto 
 
 JOHN BAKER .. ..Burslem. 
 
Vlll 
 
 Mr. SAMUE,L TAYLOR. 
 -JOSEPH HOLT ... 
 WILLIAM UHEAD. 
 JOSEPH SNAPE... 
 MATTHEW CONDLIFF, Earthenware Manu-\ ,.,.,,,,, 
 
 THOMAS MAYKtt ditto 
 
 JOSEPH BOURNE Dcnbij. 
 
 WILLIAM UATCLIFF Sltsito,,. 
 
 JOHN WILKINSON Whitehacen. 
 
 SAMUEL MOORE Sunderland. 
 
 JOHN HAWLEY London. 
 
 HUGH BARLOW ditto 
 
 RICHARD NE WBOLD ditto 
 
 WILLIAM WATTS Axhbu \\'<>ld* 
 
 THOMAS SHARPP] XinulUm-oti: 
 
 Messrs. LOWNDES & HILL ,S7oAr. 
 
 MASSEY & LEAK liHrxb-ni. 
 
 JOHN & WILLIAM PRATT Ft>nton. 
 
 C. & W. K. HARVEY ..Lengto*. 
 
 DIXON, AUSTIN & Co. (2 C.) Sundtrland. 
 
 SEWELL & DONKIN NeirctixtU'. 
 
 ANDREW MUIR & Co Gretnock. 
 
 SHORTRIDGE, SAWYER & Co South Slii,>l, 
 
 ANTHONY SCOTT & SONS Hnndcrbtinl. 
 
 BEV. W. COOK : Brlfnxt. 
 
 Mr. E. ATT WOOD, Glass Manufacturer Htnub'rhind. 
 
 J. BAILEY", Colour Manufacturer LoiK/fon. 
 
 Messrs. MARSH & HAYWOOD, Earthenware Manu-1 w 7 - 7/ 
 
 m i / 7)/*O// H fill IS. 
 
 facturers / 
 
 HULSE, JAQUIS & BARLOW ' 
 
 CHARLES SALT 
 
 CHARLES HOLBROOK, Lead Manufacturer. . .. 
 Messrs. BRAMELD, Rockingham Works 
 Mr. JAMES MAGUIRE, Artist ,S7o/,v. 
 
 ISAAC SHARPE .S/. th-b-ns. 
 
 RICHARD MULLOCK .Mn month. 
 
 JOHN TOMLINSON 
 
 THOMAS SILVESTER 
 
 RALPH LOVATT J,onyt<>,t. 
 
 BENJAMIN LINDOP nnnniliill*. 
 
 WILLIAM WILLOUGHBY SHAW M t fin-ln>xter. 
 
 LEVI HANBY. RHEAD liitrxb-m. 
 
 SAMUEL MEIR ditto 
 
 THOMAS BURGESS . . Uwfc '/ 
 
DEDICATORY PREFACE. IX 
 
 THE delightful idea I gratefully 
 cherish, that your distinguished Patronage of 
 this Volume results from the wish for Science 
 to perfect the Manufactures of PORCELAIN, 
 POTTERY AND GLASS. 
 
 Under your sanction, to equalise the infor- 
 mation current, my Researches and Experi- 
 ments are published, instead of being deposited 
 with my children, and their usefulness dimi- 
 nished. The purpose is not to teach the 
 manipulations of the Plastic Art. To persons 
 practically acquainted therewith, to presume 
 to supply written instructions and directions 
 
 would be only to sacrifice time and labour ; 
 
 j 
 
 while to those ignorant thereof, scarcely can 
 they be so clearly detailed as by them may be 
 communicated or acquired the knowledge to 
 reduce them successfully to practice. 
 
 The Bark bearing the matereil of progressive 
 advancement may be delayed by that indif- 
 ference which declines or withholds the needful 
 supply of stores ; or be hindered or prevented 
 by that timidity which imagines the voyage 
 too inauspicious to be attempted ; or for want 
 of a pole-star for its direction, in presuming to 
 breast the billows of the trackless main, may 
 encounter the danger of being stranded by that 
 
DEDU'ATOHY IMIKFACK. 
 
 contumely whioh measures mental by pecuniary 
 
 store ; and it cannot, without some difficulty, 
 he safely piloted into port : yet no sufficient 
 reason lias heen assigned, that there should he 
 longer delay in taking advantage of the current 
 of scientific research, and the tide of general 
 improvement to bring these Manufactures with- 
 in the safe harbour of immutable certainty. 
 
 Dr. Priestly very pertinently remarks : 
 "Those persons are deservedly disappointed 
 who, for the sake of a little more reputation, 
 delay publishing their discoveries till they are 
 anticipated by others." But (except Fourcroy 
 and Brongniart*) not one philosophical chemist 
 
 * " This distinguished cultivator of the Science of Potting is- 
 preparing a History of the Art of Pottery, and making great ex- 
 ertions for the formation, at Sevres, of an extensive and instructive 
 collection of everything relating to the Art. He has distributed 
 a Circular, which is inserted in different Philosophical Journals, 
 and is a useful model of such letters missive, as evidence of the 
 comprehensive views of the collector, and of the relaxation of the 
 French government with regard to the Customs' regulations in 
 scientific importations. Both Art and Science have hourly to 
 regret the obstructions and losses produced by the interference of 
 the Custom-house officer. 
 
 14 In a letter, dated March 8, 1836, addressed to the editor of 
 tiilliman'* Journal, is this statement : 4 1 am much occupied with 
 a work upon the history of the Plastic Art, or the Art of Pottery ; 
 and the requests which I take the liberty to annex, have for their 
 object the enriching of a grand and instructive collection which 1 
 I have formed at Sevres, of everything relative to the Art of 
 Pottery.' 
 
DEDICATORY PREFACE. XI 
 
 of celebrity, continental or native, until Fara- 
 day stepped aside from his systematic studies 
 of the characteristics of Atoms to investigate 
 these arts ; 
 
 " Royal Manufactory of Porcelain, and for Painting on Glass. 
 Sevres, March 8, 1836. 
 
 UNITED STATES OF AMERICA. 
 
 (Circular.) 
 
 ' ' Instructions as to the manner of co-operating towards the 
 completion of the Collection relative to the Arts connected with 
 the Manufacture of Porcelain, and with vitrification, founded at 
 the Eoyal Manufactory at Sevres, near Paris : 
 
 "1. What kinds of pottery are used by the different classes 
 of inhabitants of the country : the agriculturists, the mechanics, 
 citizens and merchants, poor and rich ? 
 
 " Is the pottery of native or foreign manufacture ? 
 
 "If foreign, from what country does it come, and in what 
 way? 
 
 "If of native manufacture, where is it made ? 
 
 " 2. As to the NATIVE POTTERY (and under this name we 
 include all varieties, from the most common to porcelain), it is 
 desired to collect and procure specimens of every sort. Common 
 pottery, both with and without glazing. Delftware common, and 
 Delftware fine. Pottery of brown free-stone ; crucibles. Varie- 
 ties of porcelain. Bricks, both common and those manufactured 
 by particular processes. 
 
 "Plate species. Plates, oval dishes. 
 
 " Hollow ware. Cups, salad-dishes, tea and coffee-cups. 
 
 " Eound pots, hollow-moulded. Oval and square pieces, 
 saucers, boxes, etc. 
 
 " The largest piece of each sort that is made. 
 
 " The name given in the country to each piece. 
 
 " The price of each upon the spot. 
 
 " Whether there is exportation, and to what place. 
 
Xll DEDICATORY PKKFAC K. 
 
 and by some interesting elucidation of the most 
 general laws hitherto developed, or practical 
 suggestion for improving the processes, be- 
 
 " 3. FABRICATION. 
 
 ..-' " 1. Materials for the Mass, or Paste. Clays. Marls, or 
 Plastic Earths which may be substituted for them. Sands. 
 Eocks on stones. Limestone. 
 
 " For the Glaze, or Enamel. If stony materials feldspar- 
 stones. 
 
 " If Metallic matters Metals, their oxides, and metallic glass. 
 
 ".Exact localities from which these materials are drawn. 
 
 "2. Modelling. Moulds of plaster, of terra cotta, or other 
 materials, of whatever kind. 
 
 " The lathe and other instruments for fabrication. 
 
 " Sketches, with exact dimensions of these instruments, if it is 
 supposed that they differ from those used in Europe. 
 
 " 3. Baking. Form of the ovens, sketched, with the dimen- 
 sions. 
 
 " Combustibles used, indicating them in the clearest manner 
 possible. 
 
 ' 4. Information peculiar to the country. 
 
 "1. To designate the principal Manufactures of Pottery, 
 Glass and Porcelain, in your vicinity. 
 
 " 2. Whether there is in North America ancient pottery ; that 
 is to say, pottery fabricated in remote ages, and which has not 
 been made for a long time. This pottery is found, in general, 
 in alluvial soil, in the ruins of towns, and perhaps, as in some 
 parts of Italy, of South America, and ^of the oriental countries 
 of the ancient world, in the graves or tumuli. In Europe, these 
 things have often been admitted into Museums as monuments of 
 antiquity, but almost never as in relation to the Art of Pottery 
 and its history. It is in this latter point of view that I regard 
 them, and that I have collected a great number of the ancient 
 pieces of pottery in the Museum at Sevres. 
 
 " To endeavour to collect some pieces of this antique pottery, 
 and to indicate exactly the place and the circumstances in which 
 
DEDICATORY PREFACE. Xlll 
 
 stowed on it some permanent mark of his 
 casual notice. 
 
 Philosophy claims to direct the most ela- 
 borate and minute manipulations of British 
 
 they have been found, and to endeavour to decide whether it had 
 anciently any celebrity, always however mistrusting the deception 
 of the sellers. 
 
 " 3. Whether there is knowledge from traditions, inscriptions, 
 etc., that the natives (aborigines) of North America have ever 
 fabricated or known glass. 
 
 " General Instructions in Relation to the Purchase, Packing and 
 Forwarding of the Objects collected. 
 
 " The expenses which may be incurred in procuring the 
 Specimens and the Information will be reimbursed by the Admin- 
 istration of the Eoyal Manufactory at Sevres, upon a reference 
 to the person who shall be designated to receive the amount. 
 
 "It is expected that these expenses will not rise to a great 
 amount: it is requested, in any event, that they may not exceed 
 in any one year the sum granted, i.e., 200 francs for 1836 (8) ; 
 200 for 1837 ; at least, without a previous understanding with 
 the Administrator of the Eoyal Manufactory at Sevres. 
 
 " It will be necessary to pack the pieces with great care, and 
 to consign them to a merchant in one of the ports of France, to 
 be forwarded by way of slow transportation to the Administrator 
 of the Royal Manufactory at Sevres, forwarding also the expenses 
 of transportation. 
 
 " It will be necessary that the correspondent at the seaport 
 should write a letter of advice to the Administrator of the Royal 
 Manufactory at Sevres, near Paris, before the forwarding, in 
 order that the latter may obtain from the Director- General of the 
 Customs permission for the box to pass under seal (sous plomb), 
 and not be opened until it arrive at Paris : this is very important, 
 to the end that there may be no derangement of labels, nor any 
 breakage. It is equally important that the tickets which may 
 
XIV DEDICATORY 
 
 MANUFACTURES. Their close investigation 
 clearly elucidates the successive improvements 
 consequent on the artisan's progress in under- 
 standing, mental cultivation, correct reasoning, 
 approaches towards perfection in the Arts of 
 Life, and success in supplying ascertained 
 
 indicate the places where the pieces were made, or those from 
 which they come, should not be separated and mixed during the 
 unpacking. It is desired, therefore, that they may be fastened 
 either with glue, or w r ith good wafers, or with twine. 
 
 "Lastly, it is very desirable that there should be attached 
 to the case a separate box, either of lead or of tin, and that 
 there should be sent separately notes previously made of the ob- 
 jects collected and forwarded, taking care that a correspondence 
 be established between the objects and notes by means of a series 
 of numbers, etc. 
 
 "ALEXANDER BRONGNIART." 
 
 Magazine of Popular Science, No. XIII., pp. 66, 67. 
 
 In pages 374 and 415 of this Work, I have mentioned the 
 Bur stem Museum for the Illustration of the Art of Pottery in 
 Staffordshire, the private property of Enoch Wood, Fountain 
 Manufactory. But I feel it a duty to express my opinion, that 
 except M. Brongniart, no person has taken so much delight in 
 traversing the wide range of this vast and diversified field. The 
 latter gentleman, surpassing many in vigour of understanding 
 and capacity for profound research, alike eminent for the variety 
 and versatility of talent, and meritorious for zealous, unwearied, 
 and productive employment, in devoting to this object (which 
 I am satisfied is both instructive and entertaining) a large portion 
 of his attention, he only fulfils what he conscientiously regards 
 an important part of his duty to his country, to posterity, and to 
 the Manufacture he has so greatlv advanced. 
 
DEDICATORY PREFACE. XV 
 
 deficiencies ; and most interesting is their 
 explanation by a lucid exhibition and skilful 
 arrangement. Many of these Manufactures 
 have the invaluable auxiHum of a SOCIETY 
 specially adapted to collect the series of facts 
 which explain those modifications of arrange- 
 ment whence have originated the successive 
 improvements ; to promote mutual intercourse 
 and comparison of information, while stimula- 
 ting essays at excellence among the members 
 generally ; to excite and appropriate the sedu- 
 lous co-operation of individual researchers in 
 the utmost possible expansion of the intellect 
 the most interesting desideratum in each per- 
 son ; and, with resistless potency, to involve 
 in its circuit those minds desirous of distinc- 
 tion, athirst for reputation, or charmed with 
 participating the effulgence of truth. But, 
 
 In reference to the Potter's Art, perplexity 
 and incertitude have generally predominated. 
 Little comparison of theory with experiment, 
 and its immediate consequences, has been 
 attempted ; neither has the public mind been 
 excited by reducing complicated results to 
 simple laws, or exhibiting the need of others, 
 new and supplementary, or connecting the 
 general bearing of the important truths elim- 
 inated in the progress of discovery, established 
 
 b 
 
XVI DEDICATORY PREFACE. 
 
 by independent facts and observations, and 
 generalised by the determined connection of 
 parts. Selfishness, which always is short- 
 sighted, has hitherto governed its destinies ; 
 and disastrous has been its sway, alike to its 
 own interests and those of the community. 
 By wholly precluding, or delaying to a future 
 time, the general diffusion, the full and clear 
 detail, of that affluence of new facts, involving 
 the characteristics of the materials of the 
 numerous compounds, almost simultaneously 
 observed by several persons, and rapidly accu- 
 mulated during the latter half of the eighteenth 
 century by BOOTH, WHIELDON, BIRD, YATES, 
 BADDELEY, CHATTERLEY, PALMER, WARBUR- 
 TON and WEDGWOOD ! there have not been 
 presented opportunities for deducing tentative 
 approximations for future experience to con- 
 firm or correct, circumscribe or enlarge ; or, 
 for successful examination, with resolute and 
 rigid precision, of their ultimate composition, 
 so as to ensure their perfection by fixing it 
 on a solid basis of combination developed by 
 the employment of definite and multiple pro- 
 portions of components. The detached facts, 
 since that period, belonging to the Art, certainly 
 are very numerous ; but, alike in the full 
 records of individual statements, and in those 
 
DEDICATORY PREFACE. XV11 
 
 where the mere formulae indicate the results, 
 and careful estimate made of the arithmetical 
 mean, only few have been applied practically 
 to elucidate any one theoretical difficulty in 
 the Art ; or to supply the elements for the 
 construction of some definite General Laws to 
 connect phenomena, when carefully compared 
 with similar deductions already recorded. 
 Neither has any advantage resulted from the 
 details in the cyclopaedias of Rees, Napier, 
 Curtis and Lardner, which profess to supply a 
 clear view of the processes and manipulations 
 of the Art. The sanction of a diploma, the 
 magic of a name, prevent determination of the 
 real amount of sterling information supplied, 
 and secure currency to assertions unsupported 
 by facts or arguments, or to defective arid 
 incorrect remarks. From these trammels I 
 had to extricate myself properly to estimate 
 the weight of authority, and verify the occa- 
 sional conclusions, that I might avail myself 
 of whatever was adapted to my purpose ; and 
 very trifling, indeed, is the sum of what 
 I regard as accurate, when compared with 
 the mass presented to the reader ; the mere 
 statements of traditional dogmas. 
 
 I scarcely need advert to the unavoidable 
 and unconquerable difficulties which rise to 
 
XV111 DEDICATORY PREFACE. 
 
 obstruct the progress of those practical men 
 whose knowledge has only personal experience 
 without any theory ; whose rules are mere 
 happy contrivances, accidentally invented, and 
 found to answer their special purpose ; and 
 who see only a series of isolated processes, 
 distinct from any common principle ; while 
 they who regard only theory, see a collection of 
 abstract propositions, associated and beautiful 
 mentally, yet without practically affecting the 
 necessities and Arts of highly-civilised life. 
 Both of the parties admit the importance of 
 Chemistry in the Manufactory, as well as in 
 philosophical science ; yet of its details and 
 capabilities, competent and really useful know- 
 ledge is possessed by few among the votaries ; 
 and in the works mentioned, there is no supply 
 of the kind of information adapted to their 
 daily wants. 
 
 The expectation seems reasonable, from the 
 advanced state and increasing rapid strides 
 of Scientific Chemistry, and the light supplied 
 by those new and interesting doctrines which 
 recent researches have raised to an eminent 
 position, and because most to these Manufac- 
 tures can the researches and discoveries supply 
 useful and important information, that thence 
 will arise valuable suggestions for systematic 
 
DEDICATORY PREFACE. XIX 
 
 improvement ; that their investigation will 
 attract the energies of every one who feels 
 within himself the vocation of discovery ; that 
 the bright promise of future advancement will 
 engage the attention of both the inquiring and 
 the indifferent ; and, that, even in those who 
 have most adequate knowledge of the nature of 
 the acquisitions possible, and the probabilities 
 of further additions, there will be excited a 
 feeling of scientific exultation and gratulation. 
 The more numerous the discoveries of Che- 
 mistry, the more distinctly will be observed 
 the avenues for additional supplies. The 
 increasing demand for these, or for improved 
 combinations, incontestably proves the progress 
 of correct information, and the extension of 
 accurate scientific knowledge. The better the 
 Manufacturer comprehends the nature of these 
 discoveries, because of the exhibition of the 
 results in the form supposed best adapted for 
 the purpose, the more clearly he sees that 
 these useful Arts of Life have not for their basis 
 and object only a practical intimacy with the 
 mixing of materials, and vague knowledge of 
 products in the wares ; heterogeneous groups 
 of facts, of little avail in efficiently promoting 
 any one branch of the Arts, or concerning it 
 to afford precise information ; yet, when care- 
 
XX DEDICATORY PREFACE. 
 
 fully investigated severally in connection with 
 others of the like character, supplying the most 
 valuable aid to scientific generalisation the 
 more is formed an experimental acquaintance 
 with the condition of the different materials, 
 which, after fritting, or baking of biscuit, consti- 
 tute excellence of productions the probability 
 will the more readily be admitted, that future 
 researches will suggest methods of improve- 
 ment ; but, for which, the opportunity will be 
 lost, unless the discoveries be carefully regis- 
 tered, and the results be compared numerically, 
 with special regard that the properties asso- 
 ciated with the numbers in the different cases 
 are clearly and precisely the same. By some 
 persons they may be considered as isolated 
 facts ; but others, who pursue philosophical 
 inquiries, will find the generality of them 
 connected with useful conclusions, tending to 
 further elucidate these truly advantageous 
 branches of National Industry. 
 
 That many attempts have failed, though 
 made by persons whose experience might be 
 supposed a guarantee for success, I readily 
 acknowledge ; also, that many essays, which in 
 the closet or laboratory promised advantages, 
 could not be brought on a large scale into 
 practical ^operation ; yet "these very failures 
 
DEDICATORY PREFACE. XXI 
 
 should not dishearten the parties, but lead 
 them forward to correct results, to accurate 
 knowledge, and thus slowly and surely pave 
 the way to certainty arid success. On atten- 
 tively examining the products of the Plastic 
 Art at the commencement of the present 
 century, there is cause of gratulation at the 
 progress since that period, more than in all 
 previous, made in the several departments, 
 in the consideration and extension of theory 
 and the practical application, in the improve- 
 ment of mechanical processes and facile mani- 
 pulations, in the willingness to suggest or 
 communicate improvements, in the additional 
 number of those who are interested in pro- 
 moting the excellence of these products ; 
 and there may be confident anticipation that 
 the next twenty years will be distinguished for 
 much greater proportionate advancement of 
 this compact of genius and industry, become 
 so indispensable to the conveniences, and 
 comforts, and general usages of civilised life 
 among all nations. 
 
 The general Arrangement of the respective 
 Subjects, in the several Parts and Chapters, 
 will be understood from the Table of Contents ; 
 while ready reference to the numerous notices 
 of Particulars is supplied by a copious Index. 
 
XXI 1 DEDICATORY PREFACE. 
 
 The FIRST PART presents CHEMISTRY as 
 a , refined Science, whose numerous votaries 
 regard solely how most effectually can be 
 accomplished the progressive increase of their 
 control over the imitations of Nature's pro- 
 ductions, as well as the extension of their 
 dominion over herself. In developing import- 
 ant relations of all substances discovered in all 
 countries, Chemistry now promulgates Facts 
 in the universal language of experiment. To 
 exhibit and classify many relative to the Arts 
 of Potting and Glass Making interesting and 
 important, because their ascertained andcorrect 
 results are adapted to supersede the labour and 
 anxiety of uncertain essays is -my sole pur- 
 pose not "the most ingenious way (according 
 to Dr. Hooper) of becoming foolish, by [pro- 
 mulgating] a system [of notions and schemes] ; 
 as the surest way to prevent Truth, is, to set 
 up something in its room." But, in a manly 
 tone, and with high sober diction, and, where 
 proper, the immutable precision of arithmetic, 
 are presented the reasonings and researches at 
 this day current, of the numerous examiners 
 of the yet more numerous particulars ; free 
 jrom the customary indecisive common-place 
 phraseology, also the unphilosophical though 
 brilliant and poetical terms affiniti**, dec- 
 
DP;DICATORY PREFACE . xxni 
 
 tions, attractions, repulsions, preferences, aver- 
 sions, and similar occult words. 
 
 Many are the interesting theoretical in- 
 quiries concerning the manner in which the 
 elements exert combinative potencies transi- 
 tive and receptive, in forming compounds, 
 and these latter again in the formation of 
 substances, natural and artificial. Little could 
 be expected in elucidation of this remarkable 
 fact from the dissimilar and not seldom con- 
 flicting conclusions of different former analysts, 
 and which were only tolerable approximations 
 relative to one and the same subject, and not 
 determinations whose accuracy is admitted as 
 entitled to confidence. But the assiduous re- 
 searches of the most expert recent analysts- 
 while engaged in the most skilful and delicate ex- 
 periments, and numerous syntheses consequent 
 on the operose analyses of substances by pro- 
 cesses the most improved, and whose accuracy 
 precluded disputes concerning the components 
 and proportions have supplied many proba- 
 bilities, that it presents a series of multiples of 
 a common force (as stated, pages 35-62), whose 
 clear development and full comprehension only 
 can supply ability to precisely determine their 
 limits of error ; like as the atomic weights of 
 the elements themselves, from other facts, are 
 
XXIV DEDICATORY PKl.K.U K. 
 
 regarded as multiples by a whole number of a 
 common weight that of hydrogen. 
 
 The mathematical elucidations introduced 
 I regard as alike pertinent and indispensable : 
 and not because less toilsome than experiment, 
 neither as the subterfuge of human pride to 
 evade the concession of human imperfection. 
 When our vt knowledge of the chemical and 
 physical properties of bodies which surround 
 us. as well as our imperfect acquaintance with 
 the mysterious modification or change of their 
 combinations, concur to convince us of the 
 same fact, we must remember, that another 
 and a higher science itself, yet more boundless, 
 is also advancing with a giant's stride, and 
 supplying expressions, which are to the past 
 as history, and to the future as prophecy ; it 
 is preparing its fetters for the minutest atoms 
 in nature, it becomes continually the more 
 necessary at every step of our progress, and it 
 must ultimately govern all the applications 
 of science to the Arts of Life, the Science of 
 Calculation."- -BABBAGE. 
 
 Here it may be proper to mention that, 
 while employing ingenious investigations, ori- 
 ginal experiments, and tentative calculations 
 for the better development and further ex- 
 tension of these particulars, I. noticed the 
 
DEDICATORY PREFACE. XXV 
 
 PRINCIPLE which is detailed (pages 46-49). It 
 seemed too important to be hastily adopted 
 from a few casual observations ; and its appli- 
 cation to many compounds whose components 
 combine by virtue of the opposite equilibria 
 of combinative potency, also to others, pro- 
 ductions of nature, which have been subjected 
 to the most scrupulous and ingenious analysis 
 and the verification thence obtained, were 
 most carefully examined ; and, reasoning that 
 what occurs in these instances will very 
 probably ensue in many others, I have ven- 
 tured to record it, though the effect which 
 it has on my mind may differ from what it 
 has on the minds of those whose contracted 
 capacities lead them, when judging of great 
 discoveries after they have been made, and of 
 which the simplicity excites their surprise, 
 and the supposition, often censoriously pro- 
 mulgated, that little difficulty was involved 
 in apprehending the subject. 
 
 Wishful to help the Manufacturer to 
 obtain adequate ideas, and full and clear 
 comprehension of the properties and compo- 
 sition of the various MATERIALS he receives, 
 and to enable him to ensure most advantage 
 from what are good, and secure himself from 
 that cupidity which supplies deteriorated sub- 
 
XXVI DEDICATORY PKEFACE. 
 
 stances, -in addition to mention of apparatus, 
 I have fully detailed ready and correct methods 
 G Analysis, General and Particular, and the in- 
 vestigation of the peculiar state of equilibrium 
 of combinative potency in the respective com- 
 ponents of the inorganic ingredients used in 
 forming the^.4 rti/icial Silicates BODIES,GLA ZES, 
 GLASSES, COLOURS, etc., and to verify the 
 researches of persons, synthetically in com- 
 pounding these, and analytically in separating 
 their various components. The path may 
 appear long to some, who wish solely to regard 
 practical investigations ; but those who desire 
 to have the full advantages of order and of 
 generalisation, will follow its windings atten- 
 tively ; and any new views which may thereby 
 be enjoyed, will interest mostly the philoso- 
 phical inquirer. When the mind, calm with 
 experience, by the rays of the lamp of science 
 investigates and discriminates the character- 
 istics of substances, they clearly appear, as 
 useful or valueless, adventitious ingredients 
 mechanically mixed, or essential and chemical 
 components, and a compound of different ele- 
 ments, or of varied proportions of the like 
 elements. The hope is indulged, that with 
 these methods, and the principle above noticed, 
 to guide future combinations, gradually will 
 
DEDICATORY PREFACE. XXV11 
 
 diminish the present prevalent obscurity and 
 confusion ; and, by the practical knowledge of 
 which are in all cases real proximate principles, 
 as well as which are incompatible ingredients, 
 seldom will be employed a compound, destruc- 
 tible by the usual alternations of temperature ; 
 but all will be regular, so that with accuracy 
 each production of the laboratory may have its 
 proper place assigned it in a chemical arrange- 
 ment. I therefore press on the young Manu- 
 facturer assiduous attention to the details in 
 the First Part. 
 
 The SECOND PART contains numerous 
 original, and I trust, valuable observations. 
 There appeared propriety in commencing with 
 the Progress of the Manufacture of Pottery, from 
 earliest times, from incidental allusions, or 
 explicit mention, by historians and travellers. 
 Where conflicting testimony left the subject 
 questionable, I have attempted to decide.* 
 
 With reference to the SCIENCE or MIXING, 
 the Fabrication of excellent Wares, and Com- 
 pounding of Bodies, Glazes and Colours, in- 
 volve the necessity for the component particles 
 to be by some means brought into due and 
 almost mathematical juxtaposition ; and this 
 
 * On the history of Glass-Making, I must refer the reader 
 to Mr. Cooper's Glass Manual. London, 1835. 
 
XXV111 DEDICATORY PREFACE. 
 
 only can be accomplished by the aid of the 
 mill, with which, in the opinion of persons of 
 adequate experience, the most careful manual 
 mixing will never compare. The Manufac- 
 turer's success is involved in the economical 
 and scientific determination of the precise f/uan- 
 tities of Components of Body, Frit, and Glaze ; 
 yet dependence is placed on the Gwws (only 
 occasionally correct) of the Mixrrs, and the 
 slip-maker's judgment of the semi-fluid in the 
 slip-tank. The first opinions and predilec- 
 tions (however absurd) of practical men, being 
 entertained and cherished as First Principles, 
 not to be rejected or questioned, must be 
 admitted as a chief obstacle to improvement. 
 But others, equally insuperable, have a very 
 different origin : persons enjoying opulence and 
 rank remain indifferent to the processes, or 
 entirely ignorant of the principles, whose de- 
 velopment, either more or less remote, has 
 been the prolific source of their elevation. 
 
 In 1823 great expectations were enter- 
 tained that the Scientific Improvement of the 
 Plastic Art would follow the posthumous 
 publication of the Recipe* and rrocewes of 
 Mr. Thomas Lakin, during many years the 
 manager of a large establishment, which pre- 
 sented unusual opportunities for the develop- 
 
DEDICATORY PREFACE. XXIX 
 
 ment and appropriation of talent in these 
 manufactures. It was conjectured that his 
 memorabilia would present the subjects that 
 had occupied his chief attention ; and that 
 with the prophetic sagacity of a powerful 
 mind, he would anticipate the Art's future 
 progress, and develop the processes that 
 would promote most effectually their suc- 
 cessful advancement. But as the published 
 formulce did not bring down to that day even 
 the knowledge then current, every purchaser 
 has expressed disappointment. Had Mr. Lakin 
 possessed the ability and inclination for im- 
 provement of the Art, and instead of observing 
 all the ordinary methods, perhaps not the most 
 ready or useful, and at hours merely in accord- 
 ance with convenience, or by accident had he 
 directed his attention even to the merely mecha- 
 nical examination of any one phenomenon, not 
 to the mixed result of a chaos of heterogeneous 
 principles had he with scrupulous minuteness 
 determined the specific gravity of each kind 
 of ware, and registered the scarcely suspected 
 variations thereof resulting from varied propor- 
 tions had he directed his investigations to the 
 detection of the proximate causes and efficient 
 remedies of crazing had he reiterated ex- 
 periments, under each possible condition, to 
 solve the beautiful problems of the best Body, 
 
XXX DEDICATOBY PEEFACK. 
 
 and Glaze, and Colour in each series had 
 he taken advantage of the important situa- 
 tions he often occupied to carefully study 
 the influence of humidity upon the earths, 
 alone or mixed together, and of varied 
 temperature on their amalgamated masses, 
 or on the compounds of earths and alkali- 
 had he in these, or in other equally interesting 
 and fertile paths of inquiry, added to the 
 current amount of knowledge of the connec- 
 tion of cause and effect in these peculiar and 
 intricate as well as interesting and important 
 Manufactures he would have conferred, at, 
 perhaps, less expense of time and labour, and 
 certainly of personal credit, an infinitely 
 greater boon upon the Art he professed to 
 promote, than by recording the forniulce 
 posthumously published by his family. 
 
 But in vain do we seek therein for facts 
 elicited by the progress of experimental science ; 
 or exposition and elucidation of the reciprocal 
 potencies of materials ; or explanation of the 
 causes, and exhibition of the ready and efficient 
 remedies, of the disastrous failures frequently 
 occurring. The omission, whether from in- 
 capacity, or neglect, or disinclination, involves 
 in disrespect the memory of Lakin. Yet I think 
 the fault really can be found in the mystification 
 adopted by these cherished opinions, as well as 
 
DEDICATORY PREFACE. XXXI 
 
 by those of his predecessors. As far as any 
 proofs have been published, even Wedgwood, 
 whose celebrity has been circulated throughout 
 Europe, does not appear to have had definite 
 and clear ideas of the Chemistry of Pottery, or to 
 have entertained just notions of the true nature 
 of Chemical Combination ; for there is great 
 probability that he suffered himself to be mis- 
 led by vague and groundless hypotheses on the 
 cause of the adhesion of ingredients in the 
 Bodies, Glazes and Colours of the Wares, as 
 though the particles respectively were wedged 
 so closely together, that separation became next 
 to impossible. Although proved to be hypothe- 
 tical, and not countenanced by either sound 
 reasoning or fact, his statements relative to his 
 pyrometer were admitted without proof, and 
 for some time regarded as the true measure of 
 the potency with which heat solicits solid 
 substances. But, for examining with great 
 sagacity the current manipulations, for laying 
 the foundation of the practice of best workman- 
 ship, by establishing the means whereby at 
 that time could be secured and determined 
 4ts relative goodness, his merit is indisputable, 
 and justly entitled to the gratitude of posterity. 
 After any deductions from his merits, which 
 may justly be made because he did not produce 
 Porcelain and Ornamented Printed Wares, 
 
XXX11 DEDICATORY PREFACE. 
 
 he must : be allowed to occupy the highest 
 place among those of our countrymen who 
 have advanced the Plastic Art to its present 
 rank. Little did contemporary Manufacturers 
 wish to aiward the great amount of credit 
 due to the party who at once perceived the 
 value of a casual observation, or of an unex- 
 pected result ; who discriminated which facts 
 are trivial, ahd which are important ; and 
 selected the latter to guide him through diffi- 
 cult and perplexed mazes of investigation. 
 
 A few persons, of whose liberal views a high 
 opinion was entertained, have expressed fears 
 that the publication of this Volume w r ill injure 
 the Trade of the Districts also, and the Manu- 
 factures, by divulging the Fwrmulce for com- 
 pounding Bodies, Glazes, Glasses and Colours, 
 supplying much valuable information to 
 foreigners heretofore unattainable; and yet 
 these persons do not blame the cyclopaedists 
 for publishing very minute analyses of 
 the processes, and an elaborate description 
 of the machines employed and current in 
 every Manufactory. Knowledge, industry, and 
 integrity, are the only secrets of trade which 
 ever ensure respect and wealth, and to whose 
 possessors the exposure cannot be injurious. 
 Individual and general advantage result 
 from appropriating light from all quarters, 
 and causing it by reflection to irradiate the 
 
DEDICATORY PREFACE. XXX1U 
 
 surrounding area. And, as knowledge is avail- 
 able, precisely in proportion to the respective 
 capabilities of the persons acquiring it, every 
 invention or improvement relative to these Arts 
 will be primarly attracted to the Boroughs of . 
 Stoke-upon-Trent, Birmingham and Dudley, 
 as the most productive scenes of development, 
 where it can most profit the inventor, because 
 most profitable to the Manufactures there estab- 
 lished. Whereas, mystitiers, who betray a jeal- 
 ousy of competition, often are vain persons, 
 guilty of the silly blunder of estimating their 
 own intrinsic resources above those of all the, 
 world besides ; some ingenious neighbour has 
 supplied a few hints, upon which they work in 
 secret, and outmanoeuvre themselves by trying 
 to steal in the dark a march upon their friends, 
 excluding every observer, and in turn becoming 
 insulated and excluded, absence of external 
 illumination promotes their adumbration, till 
 a few years of exclusiveness places them in the 
 market, with inferior goods and higher prices, 
 yet deprived of their oldest and best customers. 
 The advancement of the Manufactures will 
 be most efficiently promoted by the skilful 
 potter and glass-maker knowing the treasured- 
 up recipes secret and invaluable! afford- 
 ing, in the simplest form, the supplementary 
 traditional information of many now vanishing 
 
XXX) V DEDICATORY PREFACE. 
 
 from actual practice, unexpectedly extending 
 the views of the various combinations once pre- 
 valent, often supplying links(otherwise absent) 
 to unite the numerous subjects in a continuous 
 and unbroken chain, and also, means of refer- 
 ence for ascertaining the steps by which were 
 acquired the results. However much some of 
 those of the Plastic Art approximate to others 
 practised by predecessors abroad, or contempo- 
 raries at home, yet, as the extraordinary pro- 
 ductions of native and uneducated sagacity of 
 intellect, they challenge warmer admiration, 
 and the merit of originality ; and, of their 
 qualities, because of changes in components or 
 proportions, ignorance is not desirable anymore 
 than is inability to comprehend combinative 
 potency and recipience. By such a method of 
 comparison, the aggregate of the respective 
 components of each kind of product generally 
 presents an assemblage almost identical and 
 their subordinate distribution is chiefly affected 
 by their diverse chemical composition. Nature 
 is, doubtless, the Manufacturer's best director ; 
 and yet, by means seemingly most simple, she 
 obtains the most grand and correct results. To 
 present the scientific experimenter with oppor- 
 tunity for a close and severe scrutiny of the 
 series of means employed to imitate these results, 
 is to bring within probability suggestions and 
 
DEDICATORY PREFACE. XXXV 
 
 additions whose importance and value are not 
 easily calculated and determined. On this 
 account, kept in the privacy of the Manufac- 
 turer's office, or mixing room, each recipe is 
 little more than a mere appendage, as com- 
 pletely unconnected with the promotion of sci- 
 entific improvement as are specimens of Natu- 
 ral History exhibited in itinerant museums. 
 The Formulae are presented in cenfaxsimal 
 proportions, the more easily to ensure accuracy 
 in compounding each, also excellence of results 
 in accordance with the combinative potencies of 
 the competent materials. It is expected that 
 the defects or errors which may arise will be 
 easily understood, and the proper remedies also, 
 by him who can comprehend and usefully apply 
 the calculations introduced, and repeat the ex- 
 periments for assigning with confidence the 
 proportionate components for each respective 
 compound. CRAZING is a problem whose 
 accurate solving is of the highest interest ; and 
 I cannot think otherwise than that the time is 
 approaching w^hen the attempts to entirely 
 prevent it will be completely successful, and 
 also much more common than can now r be 
 admitted. For this desirable object, seemingly 
 we must be content to proceed gradually , avail- 
 ing ourselves of the researches of celebrated 
 experimenters, and the advanced state of Che- 
 
XXX VI DEDICATORY PREFACE. 
 
 mistry. To gradually diminish uncertainty on 
 this subject, I have stated from careful experi- 
 ment and sound theory different suggestions ; 
 even although the value of some may be less 
 than the errors of remark, or the unavoidable 
 incertitude consequent on the presence of im- 
 perfectly understood active causes. And, ad- 
 mitting that there may be a limit beyond which 
 human perseverance cannot carry the approxi- 
 mation to truth, and one, much wider, within 
 which some of the many trials made will not 
 possibly come, yet by such means as are here 
 mentioned will uncertainty progressively di- 
 minish, will truth be separated from error, and 
 will be eliminated with precision the actual 
 anomalies already brought under consideration. 
 The Manufactures will continue without a 
 solid basis, or the true dignity of a science ; 
 and will abound in empirical rules and incon- 
 sequential reasonings, until fully are compre- 
 hended the PROPERTIES or HEAT, concerning 
 whose vast importance in the economy of nature 
 and in these (and probably all other) Manu- 
 factures, very imperfect and crude notions are 
 entertained by potters especially. Each of the 
 several components of Bodies, Glazes, Glasses 
 and Colours, has peculiar relations, which pay 
 varied and varying behaviour to its action in 
 the extremely high temperature of the potter's 
 
DEDICATORY, PREFACE. XXXV11 
 
 oven ; and which require to be clearly ascer- 
 tained, " et ignem regunt numeri.".- -FOURIER. 
 The clear recognition of the Laws which re- 
 gulate its general distribution ancj propagation 
 in solid substances, forms the first, the most 
 important, yet profoundly difficult problem in 
 the theory, to be solved ; and it is one of the 
 most interesting investigations of tlie Arts, be- 
 cause of beingessen tial to all accurate knowledge 
 of the Causes of the Combination of Earths, 
 every department of which is, subject to its 
 potency. However great may be the difficulties, 
 yet as accurate means have fyeen adopted to 
 elucidate and determine raariy of them, the 
 hope isentertained that only of very short dura- 
 tion will be the present prevalent ignorance. 
 -,, The THIRD PART comprises TABLES of the 
 Characteristics of Substances, on which is firmly 
 based the more exact Cheipistry of the present 
 day. These have been investigated by dif- 
 ferent persons with minute an4 rigid precision ; 
 and of the utility of presenting them, in extent 
 and arrangement, different and superior to all 
 I have had opportunity to exaipine, I antici- 
 pate the approbation of every adequate judge. 
 Son^e persons have occasionally suggested 
 that future generations will minutely investi- 
 gate the reasonings and observations herein 
 promulgated, and wilLgiye.a-n opiiiipn on their 
 
XXXV111 DEDICATORY PREFACE. 
 
 relevance to the subject, as well as on their 
 merits, at a day when will be well known the 
 particulars of which I have treated I shall 
 be excused the vanity of believing this. I have 
 intentionally delayed the completion of the 
 Work that I might the better fulfil my obliga- 
 tions to the Subscribers, and the duty I owe to 
 the Manufacturers generally ; not that I am 
 either required or expected to penetrate into 
 the progress of the Art beyond the possibility 
 of improvement. And, having collected and 
 preserved most of the important Facts now 
 current, also endeavoured to supply useful in- 
 formation heretofore unpublished, arid to excel 
 in what had never been previously attempted, 
 I am fearless of any criticism ; because, for it 
 to be pertinent, it must further promote the 
 Object I most desire the Advancement of 
 these Arts to unparalleled excellence. 
 
 Of the necessity for all possible Improve- 
 ment of these Manufactures no doubt can be 
 entertained. The most fixed principles of 
 human nature, the examples of all history, 
 prove the fact that should foreign rivalry 
 ever be successful, it will do little less than 
 utterly extinguish these staple Trades ; whose 
 present elevation will be the exact measure of 
 their depression, because precisely that of the 
 jealousies andexcitements of the rivals, who will 
 
DEDICATORY PREFACE. XXXIX 
 
 continue fearful of being surpassed, and never 
 rest certain of pre-eminence while there re- 
 main the smallest vestiges of manual expert- 
 ness, or specimens that talent has existed and 
 been encouraged, or artisans excited by ade- 
 quate remuneration, and, until our ingenuity 
 lies torpid, our commerce destroyed, our wealth 
 dissipated, and our independence overthrown. 
 Whatever attention may be due to the 
 previous remarks, I would appeal to sentiments 
 more elevated. An adequate idea of the im- 
 portance of Progessive Improvement requires 
 the mind to be raised to a suitable level, that 
 the views may contemplate a distant futurity, 
 and consequences the most certain, however 
 remote. As far as concerns the interests of the 
 Manufactures, YOU, MY PATRONS, are, in fact, 
 the Federal Representatives of British Potters 
 and Glass Makers. You must determine how 
 shall be effected the latest Improvements ; their 
 commencement is entrusted to you ; and on 
 you depends the excellence of subsequent 
 productions. If Invention, after lying torpid 
 on the coasts of Italy, be desuetude in Stafford- 
 shire, where shall it ever emerge from the 
 darkness in which the Arts will be involved ? 
 You, then, must decide, whether that Genius, 
 at whose voice Germany, and France, and 
 Britain, awoke from the sleep of ages, to contest 
 
xl DEDICATORY PREFACE. 
 
 the career of excellence in the useful and the 
 ornamental : and by whose magic touch the 
 crude supplies of nature are converted into 
 Articles, to embellish life with conveniences for 
 use or luxury ; that Genius, which has poured 
 wealth into the laps of its votaries, shall be 
 cherished, and protected, and encouraged ; or 
 be invested in a funeral pall, and wrapt in 
 eternal gloom. I anticipate yourdecision. The 
 Patronage afforded me manifests your solici- 
 tude to approve yourselves worthy of the digni- 
 fied trust ; and the difficulties which will have 
 to be surmounted, the arrangements which 
 must be made, and the essays to be accom- 
 plished, are not to be mentioned in comparison 
 with your anxiousness to mingle in the strife 
 for perfecting the Manufactures. 
 
 One favour more I most urgently yet 
 respectfully solicit : To preclude from obtain- 
 ing Information at your expense, persons who 
 were unwilling to patronise the publication of 
 this Volume ; do you resolutely disregard every 
 importunity by persons not in the List pre- 
 fixed, for its loan, or perusal, until the expira- 
 tion of twelve months after its delivery. 
 
 I remain, with unfeigned gratitude, 
 Your obliged, humble Servant, 
 SIMEON SHAW. 
 
 Tunstall, July, 1837. 
 
CONTENTS. 
 
 PART THE FIRST. 
 
 A N A LYSIS AND MATERIALS. 
 
 CHAPTER I. 
 
 INTRODUCTION 
 
 Laboratory and Apparatus. . . . 
 
 ELEMENTS 
 
 Combinative Potencies 
 
 Manipulative Processes for\ 
 Analysis and Reagents f 
 
 Pulverisation 
 
 Blowpipe Analysis 
 
 Humid Analysis 
 
 Preparatory Manipulations . . 
 General Analytic Processes . . 
 Compounds Soluble in Water 
 
 not Soluble only) 
 
 in Acids 
 
 - Mixed, Soluble) 
 in Water / 
 
 Ditto in Acids .... 
 
 Ditto, Insoluble . . 
 
 Page. 
 
 17 
 25 
 35 
 
 63 
 
 83 
 85 
 107 
 110 
 115 
 122 
 
 125 
 126 
 
 132 
 137 
 Particular Analytic Processes 141 
 
 CHAPTER II. 
 
 TEMPERATURE 157 
 
 Coal 179 
 
 Steam Heat for Printers' Stoves 193 
 
 CHAPTER III. 
 
 ACIDS AND ALKALIES 195 
 
 Boracic Acid 202 
 
 Muriatic Acid 207 
 
 Nitric Acid 209 
 
 Sulphuric Acid 211 
 
 Potash. 215 
 
 Soda 219 
 
 Lathia .,. , 226 
 
 Calculation of Chemical Se- V 097 
 
 parations J 
 
 CHAPTER IV. 
 
 Hage. 
 THE EARTHS 229 
 
 Alumine 232 
 
 Clays 234 
 
 Silica 237 
 
 Flint 245 
 
 Lime 253 
 
 Plaster of Paris 256 
 
 Magnesia 258 
 
 Barytes 262 
 
 Felspar 266 
 
 Grauen (or China Stone) .... 270 
 
 China Clay 273 
 
 Chert 277 
 
 CHAPTER V. 
 
 METALS 279 
 
 Reciprocal Combinative Po-^ ^^ 
 
 tencies of the Metals . . ' 
 
 Antimony 305 
 
 Arsenic 308 
 
 Chromium 309 
 
 Green Oxide 313 
 
 Cobalt 314 
 
 Chromic Acid ib. 
 
 Humid Separation of Nickel ) .^-t 
 
 from Cobalt J 
 
 Arsenite of Cobalt ib. 
 
 Copper 324 
 
 Gold 328 
 
 Iron.. 334 
 
 Lead 336 
 
 Manganese 342 
 
 Platinum 348 
 
 Silver 352 
 
 Tin 355 
 
 Zinc.. -359 
 
xlii 
 
 CONTENTS. 
 
 PART THE SECOND. 
 
 SYNTHESIS AND COMPOUNDS. 
 
 CHAPTER I. 
 
 Sketch of the Origin and) 
 Progress of the Art . . . . * 
 
 CHAPTER II. 
 Science of MIXING Scienti- 
 
 Page. 
 
 fie Principles of the Ma- 1 
 nufacture Combinative | 
 Potencies of the Earths J 
 
 CHAPTER III. 
 
 BODIES .................... 441 
 
 Porcelain Hard ............ 445 
 
 - Fritted Bodies ____ 451 
 
 - Raw Bodies ...... 452 
 
 Soft .............. 455 
 
 Fritted Bodies .............. 456 
 
 Raw Bodies ................ 458 
 
 Stone Do ................... ib. 
 
 Ironstone .................. ib. 
 
 Dry Bodies .................. ib. 
 
 Chemical Utensils .......... 461 
 
 Fritted Jasper ......... ' ..... 462 
 
 - Pearl ................ ib. 
 
 - Drab ................ ib. 
 
 Raw Chemical Uteqsils ...... ib. 
 
 -- Stone .................. ib. 
 
 Jasper ................ ib. 
 
 Pearl .................. ib. 
 
 Mortar ................ ib. 
 
 - Drab .................. ib. 
 
 --- Brown ................ ib. 
 
 Fawn .................. ib. 
 
 Raw Cane .................. 436 
 
 Red Porous ............ ib. 
 
 -- Egyptian .............. ib. 
 
 Earthenware . . .............. 464 
 
 Page. 
 Queen's Ware 465 
 
 Cream Colour ib. 
 
 Blue and Fancy Printed ib. 
 
 Dipped and Mocha 466 
 
 Chalky ib. 
 
 Rings, Stilts, etc ib. 
 
 CHAPTER IV. 
 
 GLAZES 469 
 
 Porcelain, Hard, Fritted 475 
 
 - Soft Do ib. 
 
 Raw 477 
 
 Cream Colour Do ib. 
 
 Blue Printed Do ib. 
 
 Fritted Glazes 478 
 
 Analysis of Frit 482 
 
 Glaze 483 
 
 Coloured Glazes 490 
 
 Dips, Smears and Washes . . 491 
 
 GLASSES 493 
 
 Flint Glass 494 
 
 Coloured Glasses 495 
 
 Artificial Garnet 496 
 
 Emerald ib. 
 
 Amethyst ib. 
 
 Sapphire ib. 
 
 Opal ib. 
 
 Plate Glass 497 
 
 Crown Glass 498 
 
 Broad Glass 499 
 
 Bottle Glass ib. 
 
 Phosphoric Glass 500 
 
 British Steel Glass 501 
 
 Glass-Staining and Painting 508 
 
 Engraving on Glass 511 
 
 Dr. Faraday's Experiments.. 514 
 
CONTENTS. 
 
 xliii 
 
 CHAPTER V. 
 
 Page. 
 
 OOLtDUBS. 517 
 
 Colour Making 520 
 
 Fluxes, or Solvents 526 
 
 Components of the Colours . . 527 
 
 BEDS, etc., from Gold ib. 
 
 Carmine, or Rose Colour 529 
 
 Purple 531 
 
 Reds, etc., from Iron 536 
 
 Page. 
 
 Blues -. 539 
 
 Yellows 542 
 
 Greens 544 
 
 Blacks 546 
 
 White 547 
 
 Silver for Burnishing 548 
 
 Gold for Ditto 549 
 
 Printer's Oil 550 
 
 Lustres 551 
 
 PART THE THIRD. 
 
 TABLES OF THE CHARACTERISTICS OF CHEMICAL 
 
 SUBSTANCES. 
 
 Preliminary Remarks 
 
 Page. 
 565 
 
 f 
 
 Sodium and its Compounds . . 
 Potassium ditto 
 
 age. 
 620 
 624 
 633 
 
 634 
 
 ib. 
 635 
 636 
 637 
 639 
 ib. 
 641 
 ib. 
 642 
 643 
 ib. 
 644 
 645 
 646 
 ib. 
 648 
 649 
 652 
 655 
 659 
 
 Oxygen (Tables) 
 
 572 
 
 Sulphur and its Compounds 
 Nitrogen ditto 
 
 .. ib. 
 573 
 
 Observations 630 
 
 Selenium and its Compounds) 
 (Tables) f 
 
 Chlorine ditto 
 
 .. ib. 
 
 Bromine ditto 
 
 .. ib. 
 
 Arsenic ditto . . 
 
 Iodine ditto 
 
 .. ib. 
 
 Chromium ditto 
 Vana,dinm ditto 
 
 Fluorine ditto 
 
 .. 574 
 
 Phosphorus ditto 
 
 . . ib. Molvbdennm ditto 
 
 Boron ditto 
 
 . 575 
 
 Tungsten ditto 
 
 Carbon ditto 
 Hydrogen ditto 
 
 .. ib. 
 
 .. 582 
 
 Antimony ditto 
 
 Tellurium ditto 
 
 Observations 58 
 
 4594 
 dS l595 
 
 Tantalum ditto 
 Titanium ditto 
 
 Ammonium and its Compoun 
 (Tables) 
 
 Silicium ditto 
 
 Thorium ditto 
 
 .. 599 
 
 Osmium ditto 
 
 Zirconium ditto 
 
 .. ib. 
 
 Gold ditto 
 
 Aluminum ditto 
 
 ,. 600 
 .. 603 
 .. 604 
 
 Iridium ditto 
 
 Yttrium ditto 
 Glucinum ditto 
 
 Rhodium ditto 
 
 Platinum ditto 
 
 Magnesium ditto 
 
 .. 605 
 
 Palladium ditto 
 
 Calcium ditto 
 
 .. 608 
 
 Mercury ditto 
 
 Strontium ditto . ' 
 Barium ditto 
 
 .. 612 
 . 614 
 
 Silver ditto 
 
 Copper ditto 
 Uranium ditto 
 
 Lithium ditto .... 
 
 . 618 
 
xliV 
 
 CONTENTS. 
 
 Page. 
 Bismuth and its Compounds . . 661 
 
 Tin 
 
 ditto 
 
 662 
 
 Lead 
 
 ditto 
 
 665 
 
 Cerium 
 
 ditto 
 
 669 
 
 Cobalt 
 
 ditto 
 
 671 
 
 Nickel 
 
 ditto 
 
 672 
 
 Iron 
 
 ditto 
 
 674 
 
 Cadmium 
 
 ditto 
 
 681 
 
 Page. 
 
 Zinc and its Compounds 682 
 
 Manganese ditto 684 
 
 Observations 687697 
 
 Isomorphous Groups 698 
 
 Isomeric ditto 703 
 
 Metameric ditto . ; <...... 704 
 
 Polymeric ditto ib. 
 
 Index . . 705 
 
 CORRIGENDA. 
 
 On page 517 of the present issue Chapter III. appears. This is a mis- 
 print which appeared in the original. As the contents indicate, it is 
 Chapter V. 
 
xlv- 
 
 ADDENDA to Page 251. 
 
 The followinc/ Remark* were mpplied on the 28tti 
 of June, 1837, by an esteemed Friend: 
 
 " A pint of slop-flint should weigh 32 oz., and a pint of 
 water weighs 20 oz. the difference is 12 oz. so that if the 
 pint be 12 oz. deficient, or short of 32, then clearly it is 
 entirely without flint in it, and is all water ; and the total 
 deficiency in the tub of flint will be 40 pecks. 
 
 Agreeably to this method of determination, the rule 
 for ascertaining the deficiency in a tub of 40 pecks, by 
 the weight in the pint, will be : 
 
 As 12 : are to 40, : : so are the ounces deficient in the 
 pint, : to the pecks deficient in the tub. 
 
 Problem. What is the deficiency in the tub of flint when 
 the pint weighs only 29 oz. ? 
 
 Here the pint is 3 oz. short, therefore : 
 12 : 40 : : 3 
 3 
 
 12 | 120 
 
 Answer 10 pecks. 
 
 "So that when the pint weighs only 29 oz., there will be only 
 30 pecks of flint in the tub of a proper weight or liquidity ; 
 and the other ten pecks are water only, which may be easily 
 accounted for by the following reasoning : 
 
 The deficiency of 1 oz. in the pint equals a pound in 
 a peck, or 40 Ibs. in the tub. Then, in the preceding 
 example, the tub will be deficient in weight 120 Ibs., and 
 will weigh only 1,160 Ibs. instead of 1,280 Ibs. Now, 
 
 30 Pecks of flint wei-gh 960 Ibs. 
 And 10 Pecks of water weigh 200 
 
 1,160 
 Proving the accuracy of the former result. 
 
Xlvi ADDENDA TO PAGE 251 CONTINUED. 
 
 A pint of flint, when carefully evaporated dry, will 
 weigh 18| oz. ; therefore, when slop flint is charged six- 
 pence per peck, dry flint is worth 3 Is. ^\d. per ton, when 
 perfectly dry, besides the expense of drying. 
 
 A pint of grauen (china stone) when evaporated per- 
 fectly dry, will weigh Yl\ oz. Therefore, when slop-stone 
 is charged sixpence per peck, dry stone is worth 3 4s. lid. 
 per ton, when perfectly dry, besides the expense of drying." 
 
 G. B. 
 
 ADDENDA to Paye 492. 
 
 BOBACIC ACID has potency over lime exceeding any 
 other flux ; and hence the employment of borate of lead 
 is useful in the manufacture of glass that has lime present 
 in the pot. 
 
 Boracic Acid, in the heat of the potter's oven, com- 
 municates to flint an orange, and to grauen a primrose tint, 
 with intumescent mass, but smooth surface. Soda improves 
 the natural tint of both, with a bluish radiance of the 
 latter. 
 
 Problem. What proportions, fusible at 86 Wedg. 12,000 F. 
 will produce an homogeneous white transparent glass, indifferent 
 to atmospheric action ? 
 
 Boracic Acid improves the colour of bone earth, and 
 yet injures that of china clay ; soda improves the colour 
 of the clay, yet injures that of the bone earth. 
 
 Problem. What are the proportions which will most use- 
 fully combine in a glaze that will not craze? 
 
 G. B. 
 
THE 
 
 CHEMISTRY OF POTTERY 
 
 ''SX8ITY I 
 
 AMD MATERIALS. 
 
 ; The efficacy of Ignorance has long been tried, and has not produced the 
 consequences expected ; let KNOWLEDGE take its turn." DR. JOHNSON. 
 
 CHAPTER I. 
 
 INTEODUCTION. 
 
 THE ARTS OF LIFE supply instances of periods 
 when the Genius of Invention has been scarcely 
 manifested ; and others, when its progress has had 
 accelerated velocity ; among which latter the present 
 seems most interesting, because of the amazing 
 variety and extent of improvements presented to 
 the eye of the intelligent observer. 
 
 Some natural wants first supplied by the person 
 in need, and others created by the requirements of 
 civilisation prompted the spirit of invention, the 
 exercise of dexterous skill, and the subdivision of 
 labour, which distinguish commercial nations. Thus 
 commenced the several trades and professions, whose 
 votaries and adepts only first practised them as 
 mysteries, and by limiting the knowledge attempted 
 
'J CHEMISTEY OF POTTERY. 
 
 to monopolise dexterity in the processes and manipu- 
 lations. 
 
 Society, however, claims every person's endea- 
 vours to promote improvements in these Arts ; 
 and the attempts to accomplish these are usually 
 attended by a degree of remuneration in capacitating 
 the person the better to fulfil the duties of the station 
 occupied in society, and proportionately gratifying 
 that resistless desire for knowledge inseparable 
 from man's nature and condition. The advantages 
 are much greater when liberal-minded men unite to 
 extend information, explore and clear the path for 
 pursuing Science, in the divulging, comparing, and 
 illustrating of ideas, and render useful to all the 
 successful labours of men of science, who, with 
 much erudition, unite that talent, and judgment, 
 and application which distinguished sages of other 
 days, who have attempted to recommend them- 
 selves to society by an original cast of thinking, 
 and have secured the perpetual extension of current 
 knowledge, the effulgent rays of the light of science, 
 and the invaluable capability of unlimited improve- 
 ment, so that no earthly power can limit the number 
 of those who traverse the path, nor determine the 
 importance of the improvements, and the sum of 
 their additions to the stock of general information. 
 
 The details most general of the Arts of Life, of 
 extensive import in their applications, and power- 
 ful influence in our manufactures, are those of 
 CHEMISTRY one of the most useful, instructive, and 
 curious of all mental pursuits. This is the science 
 which develops the distinctive characters, peculiar 
 qualities, and combinative potencies of elementary 
 
INTRODUCTION. 3 
 
 atoms, and the reciprocal action and reaction of 
 the components of substances. When engaged in 
 its processes, the mental powers are delightfully 
 busied in scrutinising the nature and behaviour of 
 the elements employed, the union and usefulness, 
 the essential differences of the resulting products. 
 
 This science assumed its modern importance in the 
 hands of Beccher and Stahl, of Mentz ; and during 
 the last sixty years it has conferred great celebrity 
 on many self-taught men, because of their discoveries 
 how society, in conventional language, may compre- 
 hend why the unnumbered substances presented to 
 the perception are essentially as different in pro- 
 perties, as varied in components, and have a certain 
 and never any other manner of existence. Still, so 
 varied are the subtleties of Nature that a rich 
 harvest is now ripening, to be reaped by the master- 
 minds of this century. Will it be presumption to 
 hope that the diffusion of the knowledge of this day 
 current how, in accordance with certain principles, 
 substances either combine or separate, and produce 
 results may awaken the genius of some other 
 Priestley, or Davy, or Dalton, and secure a just 
 appreciation of true talent and perseverance? 
 
 The thirst for distinction and wealth, so prevalent 
 among mankind, strengthens the love of liberty, 
 kindles the lamp of invention, and excites to almost 
 every improvement in each of the Arts of Life. Every 
 great and useful discovery has thus resulted, not 
 from chance, but general laws governing the cir- 
 cumstances, and proving that the laws of nature are 
 not more permanent and immutable than the pro- 
 gress of society is certain. This thirst excited that 
 
 B 2 
 
4 CHEMISTKY OF POTTEEY. 
 
 beneficent addition to the stock of knowledge made 
 by the alchemists fools in the estimation of some, 
 in the present day wise only to amass wealth ; but, 
 in reality, a race of steady inquirers, of superior 
 powers of intellect, employing constant reasonings 
 on every process. Every substance, even most offen- 
 sive, they examined in their search after that chimera, 
 the philosopher's stone ; and this thirst produced 
 acquaintance with the chemical properties of many 
 substances, towards which the repugnance is so great, 
 that scrupulously would they have been avoided 
 only for this very powerful motive. Unwilling to 
 seek an object in the dark, or blunder on it unex- 
 pectedly, they carefully pursued each glimpse of light 
 along every intricacy of the labyrinth it traversed ; 
 and frequently in the ascertained characters of their 
 agents, seeking directors for future processes, they 
 remarked some peculiarity, available for one purpose, 
 yet suggesting another. During more than six hun- 
 dred years their processes Alchemy in its disproba- 
 tive force, the present approved Chemistry formed 
 an authorised science ; and its votaries and adepts, 
 the Christian priesthood (also the physicians and 
 apothecaries administering to the physical and 
 mental maladies of their flocks), only practised their 
 chemical researches in secret, after the peculiar 
 results were indeed so very wonderful to the unin- 
 formed as to be supposed accomplished by infernal 
 agency, and proving the operator's compact with the 
 prince of darkness. Untutored minds, aware that 
 every effect has a cause, regard as a necessary convic- 
 tion the philosophical sequence, suppose the changes 
 in substances violent, irregular, anomalous and 
 
INTRODUCTION. 5 
 
 unaccountable proofs of particular agency. Such 
 ignorant and credulous minds, in this day, are imposed 
 on by their successors, Charlatans and Quacks ; but 
 in former days the most sagacious and intelligent 
 persons were imposed on, or astonished. And, when 
 mere parade of eccentricity was substituted for know- 
 ledge, the more obscure were the parties' perceptions 
 of the phenomena of their experiments, the more 
 symbolical and figurative became their language, the 
 better to conceal their pretended secrets from the 
 uninitiated and the ignorant.* 
 
 One of this notorious fraternity, DE BOTSCHER (of 
 whom, hereafter, I shall speak more in detail), at the 
 commencement of the 18th century, developed the 
 transmutation of Rocks into the hitherto-unrivalled 
 Dresden Porcelain more valuable to his country 
 than could have been the discovery of the philoso- 
 pher's stone. And our day has been distinguished 
 by the efficient processes of the greatest alchemist 
 on the page of history, distinguished by Napoleon's 
 epithet, as "the philosopher of England," DAVY. 
 Not content with the metals for his purposes of 
 
 * The following specimen is modest, compared with some 
 extant : " Ye wretched and pitiful medicasters, who full of deceit 
 breathe I know not what Thrasonick brags ; infamous men, more 
 mad than Bacchanalian fools, who will neither learn, nor dirty 
 your hands with coals ; you titular doctors, who write long scrolls 
 of receipts ; you apothecaries, who with your decoctions fill pots 
 no less than those in princes' courts, in which meat is boiled for 
 some hundreds of men ; you, I say, who have hitherto been blind 
 suffer a collyrium to be poured into your eyes, and permit me to 
 anoint them with balsam, that this ignorance may fall from your 
 sight, and that you may behold truth as in a clear glass." 
 
 BASIL VALENTINE. 
 
6 CHEMISTEY OF POTTEEY. 
 
 transmutation, he laid violent hands on the mere 
 Earths (till that moment in their peculiar char- 
 acteristics imperfectly known), he separated them 
 from every extrinsic adherent, subjected them to 
 the energies of the galvanic circuit, watched their 
 behaviour when thereby solicited, and enjoyed the 
 high gratification of receiving from the respective 
 substances their elementary bases, as METALS. To 
 him contemporaries of various nations have awarded 
 the meed of acclamation ; and his name will be 
 remembered while science preserves her records. 
 The alchemists would have discarded the indif- 
 ference or indolence so long prevalent in the manu- 
 facturers of the Wares from the Heterogeneous 
 Compounds supplied by Nature and Art. They 
 would have sought to be skilful adepts scientific 
 fabricators of Porcelain and Pottery, products use- 
 ful and interesting in the economy of the nation ; 
 and by ceaseless researches, and improved processes, 
 would they have advanced until those had become 
 as perfect as they are important. The manufacturer 
 of this day should proceed in like manner. His 
 predecessors, ancient and recent, had presented for 
 their acceptance few of the advantages placed before 
 him ; yet they scarcely availed themselves of sugges- 
 tions from intelligent contemporaries. In general, 
 practical men are known to be the slaves of pre- 
 judices ; unaccustomed to read, compare, reason, 
 judge ; ignorant that by the three great stepping 
 stones, observation, analogy and experiment, can they 
 ascend from darkness to light ; and that although the 
 foot may accidentally be placed on the first, yet only 
 by personal efforts can the ascent ever be completed ; 
 
INTEODUCTION. 7 
 
 acquainted with processes, dexterous in manipula- 
 tions, and familiar with products, too often they 
 regard as most presuming, in the thinking portion of 
 the community, any suggestion for improvement in 
 either, although in its favour may be the fullest 
 force of reason, and clear demonstration of the 
 advantage of the change. Restricting the Art to 
 a certain class, and scarcely supplying correct in- 
 formation, or clearly explaining all the mystery 
 during the term of apprenticeship, they do not 
 afford opportunity for extension of principles, nor 
 enable improvement to keep pace with the oppor- 
 tunities presented for the exercise of genius, even 
 where celebrated for skill in the manufactures. The 
 bulk of the population being partially ignorant of 
 what constitutes excellence, indifference prevails to 
 an extent inconsistent with public welfare ; whereas, 
 a little acquaintance with the qualities inciting to 
 a better, whenever the public mind comprehends 
 the different peculiarities, the most useful will be 
 determined and approved by the general under- 
 standing and judgment. 
 
 Frequently has been repeated the adage " He 
 who undertakes to teach himself has a, fool for his 
 scholar ; " and there is probability that its utterance 
 by persons who had passed much time in colleges 
 may have affected some weak minds, and excited a 
 fear of ridicule. But we live in a day when num- 
 bers can be mentioned to completely negative the 
 degrading stigma. However humble the origin of 
 the parties, and however great fools they were, 
 and least likely to supply examples of extraordinary 
 genius and transcendent talent when their self- 
 
8 CHEMISTEY OF POTTEEY. 
 
 teaching commenced, ere their course was com- 
 pleted they supplied indisputable proofs that although 
 self-taught they were BEST TAUGHT ; and honourable 
 refutations of the force of the adage. What nonsense ! 
 to allow it longer to influence the public mind, when 
 its foolishness is demonstrated by a host of persons 
 most celebrated as original thinkers Priestley, Davy, 
 Dalton, Farady, A. Murray, Herschel and others in 
 our own and other nations. What has elevated our 
 country to its high and proud grade in the scale of 
 nations ? The Arts and Sciences. Through which 
 of her sons ? Many of the humble and self-taught, 
 whose industry and talents would do honour to any 
 age and country; who have clearly and fully dis- 
 tinguished between hypothesis and science, and, 
 passing the boundaries of mere scholastic literature, 
 have carefully studied the ample and instructive 
 page of Nature. 
 
 In each of the processes, the phenomena result 
 when the combinative potencies of the components 
 are affected ; and he who most easily accomplishes 
 this is the most expert analyst. Correct know- 
 ledge of the behaviour of Ke-agents and Com- 
 pounds in union, and dexterity in the use of 
 apparatus, may enable him to dispense with inter- 
 mediate processes, yet obtain correct results. On 
 the composition of a substance, the reasoning from 
 the result of its analysis, without opportunity to 
 combine its elements, may be very clear ; but only 
 when the synthesis of like quantities and elements 
 supplies results every way similar to those sub- 
 mitted to analysis, do we admit the conclusions to 
 possess all the certainty of a mathematical demon- 
 
INTRODUCTION. 
 
 stration, and the practice so far perfect. Such re- 
 sults gratify the analyst, and urge him " onward " 
 to further investigations and developments. Thus 
 have been urged Beccher and Stahl, who, on pheno- 
 mena occurring, first noticed mutual solicitings of 
 the gases and the general atmosphere. Their obser- 
 vations urged likewise and facilitated the discoveries 
 of two Swedes, Bergman and Scheele, contemporaries 
 of our Priestley and the French Lavoisier. And to 
 the investigations of the science has arithmetical 
 precision been secured by another Swede, Berzelius, 
 Fourcroy, Berthollet, Gay Lussac in France ; and 
 Dalton, Davy, and Thomson in England. 
 
 Metallurgical chemistry, important and essential to 
 many of the Arts of Life, is yet, as regards POTTING, 
 palpably imperfect. There may be reasons for this. 
 The processes have been inspected by many persons 
 fully adequate to their correct description ; but they 
 have declined promulgating the information, either 
 because filling a station in society, regarded as su- 
 perior to such trouble, or fearing lest in giving pub- 
 licity to imagined secrets they should break some seal 
 of confidence. Not so proceed the pioneers of science. 
 Persuaded that there is no reason whatever why the 
 Art should not rank as a science, and well aware 
 that most subtile and peculiar are the processes of the 
 Laboratory, and the energies for the constant and 
 gradual changes by Analysis and Synthesis, separa- 
 tions and combinations, they resolutely in every 
 quarter break up the ground, and throw together by 
 far the greatest number of important facts possible to 
 be aggregated, that the Manufacturer may under- 
 stand fully the true combinative potencies and pro- 
 
10 CHEMISTRY OF POTTERY. 
 
 portions of the components, by whose reciprocal quali- 
 ties they combine in bodies, glazes, and colours ; and 
 while for the great variety of these the same few 
 materials are variously proportioned, the spontaneous 
 workings of the whole are not so obvious, and the 
 traces they leave are so delicate as afterwards to be 
 scarcely perceptible by the most experienced eye. 
 
 With an ardour of investigation only now sanc- 
 tioned, and a constant addition of products for sub- 
 jects, with rapid strides Science advances to solve all 
 important inquiries on the economical appropriation 
 of components, diminishing the expense, yet pro- 
 moting the excellence of the products and of the Art, 
 as suggested by the wants of progressive refinement. 
 Disregarding all impediments, the steady " March of 
 Intellect," and the discoveries of Philosophic Re- 
 search, will place the Art on an immovable basis ; 
 will give publicity to the new application of solidly 
 established principles, to direct and expedite all 
 attempts at alterations, and all original researches 
 for what useful purposes different materials may be 
 with advantage employed ; will exhibit in a new light 
 experimental facts, supplied by the united efforts of 
 scientific men, expert analysts, occasionally named, 
 and including many interesting inquiries which have 
 exercised the intellect of ardent admirers of nature's 
 processes ; will no longer sanction such important 
 products remaining the mere results of chance and 
 guess-work, but urge to ceaseless efforts to supply 
 data, plain and correct, for readily and certainly 
 determining the employment of materials ; will ex- 
 plain, if not with absolute certainty, yet satisfactorily 
 to the mind not influenced by the specious reasonings 
 
INTRODUCTION. II 
 
 of theory, many questions now controverted ; will 
 supply observations and experiments on interesting 
 and remarkable phenomena and their causes, here- 
 tofore completely mysterious ; the latter often results 
 of others more general of principles, which, as well 
 as the analogy of their relations, demonstrate the 
 former and others similar ; in a few words, will 
 exhibit the manipulations and processes, conducted 
 by the directions of science, as indubitable as are the 
 demonstrations of Euclid, and supply the details so 
 clear, by generalising the essential and most impor- 
 tant combinations to the capacity of any person, that 
 the principles may be established and the Art ad- 
 vanced to perfection by that unrivalled instrument 
 of improvement, which till now it had seemed com- 
 pletely to elude the mathematics. Not, however, to 
 deny that the advancement here contemplated may 
 have a limit, owing to the difference in men's natural 
 ability, and their avail of opportunity to scrutinise 
 the subjects presented (like nature's processes, sub- 
 lime and profound, different though constant and 
 uniform), leading to the search for powers and causes 
 almost as diversified as the effects, affording the 
 greater satisfaction with the simplicity of the princi- 
 ples, and the pertinence of the results. Whoever 
 first publishes these, will be the manufacturer's friend ; 
 and were several persons thus employed, assuredly 
 would valuable suggestions be made, independent of 
 any possible petty jealousies. 
 
 The manufacturer usually affects mystery in his 
 recipes, regarding them as cheaper, or better, or both 
 these, than all others ; though non-comparison of 
 them with others, in components and quantities,. 
 
12 CHEMISTKY OF POTTERY. 
 
 causes the useless expense of some which are inno- 
 cuous and inefficient. The spirit of jealous exclu- 
 siveness causes great difference, as well in components 
 as in proportions of the same component, in the 
 current formulae of even celebrated persons. With 
 some trouble have been completed the comparative 
 analysis of recipes, by their owners supposed excel- 
 lent, and which well exhibit the knowledge and 
 reasonings current in the days of guessing at propor- 
 tions. Admitting them good and useful when first 
 introduced, yet being altogether devoid of general 
 principles, they are not adapted for an improved state 
 of the Art, or to indicate any advance in the Chemistry 
 of Masses. From the directions given, also, there 
 might be the inference, that intentionally errors have 
 been promulgated to cause failures and deter parties 
 busied in research ; else, that glaring errors have 
 crept into the numbers and processes, or the parties 
 were deficient in the knowledge and verity for which 
 they have obtained credit. It must, however, be 
 allowed, that, to the manufacturer, caution is indis- 
 pensable, and must be observed ; for, by his temerity, 
 with himself the community would suffer, was he, be- 
 cause of the success of one experiment, disregarding 
 the suggestions of prudence against the excitements 
 of speculation, to act as well as argue from particulars 
 to universals, and hastily compound each body or 
 glaze proposed. 
 
 Of Operatives the most prejudiced against any 
 change the Potter of the generation last past seems 
 in the first rank habituated to regard the frequent 
 and ready performance of a process as the only pro- 
 per test of its utility and accuracy ; recollection 
 
INTRODUCTION. 13 
 
 enabling him to provide for his support with little 
 exertion, he increased in fondness for the processes, 
 and proportionately became prejudiced against the 
 new, however superior in economy of labour and time. 
 To him the name of an experimenter, on Chemical 
 Principles, was merely a synonym for a fool! and the 
 pity, contempt, or aversion of his less speculative 
 acquaintance, was the only reward of the person who 
 ventured to suggest the application of Theory to 
 Practice, to ascertain the rationale of processes, to 
 suggest the alteration of manipulations, to introduce 
 the employment of a fresh material. Yet, has any of 
 the prior class left proofs that he possessed the least 
 knowledge of Principles, and, by analogy, of their 
 reciprocal relations ? As well might we give him 
 credit for knowledge of Nature's simple modes of 
 operation, which would suggest imitation and pre- 
 clude erroneous calculations of results, as of the 
 component elements of the several materials (of their 
 peculiar potencies as agents and recipients) whenever, 
 in artificial processes, they silently expand, break, 
 evaporate, radiate, contract, disperse, or combine 
 with others. I am disposed to regard as one principal 
 cause of retarding the progress of this important Art, 
 the implicit adherence to precedents and rules of 
 days long passed, without testing those precedents 
 by Scientific Principles, and superseding all rules but 
 those which accord with the improved state of Society. 
 But, besides the Operatives, the Friends of Im- 
 provement are opposed by others, who have the 
 peculiar taste or disposition not to suffer to be intro- 
 duced into practice anything new in place of what 
 themselves know. Until very recently jealous of 
 
14 CHEMISTRY OF POTTEEY. 
 
 all innovations as needless, even when harmless 
 the monopolists of power, and the votaries of avarice 
 and selfishness, sternly and vigilantly obstructed 
 advancement in knowledge and the extension of 
 useful research, fostering whatever impeded the 
 march of Scientific Discovery, and over-awing all 
 attempts of Intellect to pass the limits prescribed 
 by their opinions and requirements. They present 
 obstacles often causing an ingenious inventor more 
 trouble than to surmount physical difficulties insepar- 
 able from new processes ; or to clearly develop and 
 explain whatever facilitates the intended purposes. 
 
 There have been expressed doubts on the pro- 
 priety of giving to the numerous Secrets of this 
 Manufacture the extension and publicity that are 
 consequent on printing them. Why any should 
 question the utility as far exceeding any possible dis- 
 advantage, I profess myself unable to determine. 
 The leading principle of a Manufacturer appears to 
 be, to employ the means best adapted and most cor- 
 rect, to appropriate to the utmost possible use what- 
 ever materials he employs. For this purpose there 
 seems a necessity for the processes suggested by his 
 experience to be directed by the liberal and accurate 
 details of science. His profits depend on the busi- 
 ness being conducted with regularity and judgment ; 
 but how the latter must be exercised without avail- 
 able knowledge is not easily determined ; though 
 readily would all be effected were the Manufacturer's 
 compounds simplified and regulated by science. 
 
 The rapid progress recently made warrants the 
 anticipation of yet much greater in every department 
 of valuable knowledge, because of the liberal commu- 
 
INTEODUCTION. 15 
 
 nications of those philosophers and philanthropists 
 who have directed their attention to promote and 
 improve whatever to the public may be indispensable 
 and valuable. Most of those, who, on the European 
 continent, have thus, by the aids of science, improved 
 the Arts of Life in very recent times, were regularly 
 initiated into her arcana, and either passed their lives 
 in the quiet of the cloisters, or because of well-earned 
 celebrity were called by their country to take an 
 active part in the drama of public life. Not such 
 has been the fact in our own country. Our great 
 improvers have been men of business, who did not 
 pursue philosophy as a profession, but by mere 
 accident found it, and then pursued it as a recrea- 
 tion, or, beneath its extended shelter, enjoyed re- 
 laxation from more weighty cares. Hence, while on 
 the continent more systematic or more logical views 
 of science were taken, England has been distin- 
 guished by more useful discoveries as by Bergman 
 and Lavoisier ; Cavendish and Davy. 
 
 Frequently have important discoveries been com- 
 pletely accidental, and made by persons scarcely 
 aware, and seldom capable of fully availing them- 
 selves, of the extent of improvement of which each 
 was susceptible from the suggestions of science ; and 
 thus the spirit of monoply has precluded even them- 
 selves from consequent advantages of their dis- 
 coveries, lest some of these should also be enjoyed 
 by others. The vast improvements accomplished in 
 those manufactures to which have been applied the 
 Principles of Chemical investigations, prove the ac- 
 curacy of the reasonings of Boyle: " The excellency 
 of Manufactures, and the facility of labour, would 
 
16 CHEMISTEY OF POTTEKY. 
 
 be much promoted, if the various expedients and 
 contrivances which lie concealed in private hands 
 were, by reciprocal communications, made generally 
 known ; for there are few operations which are not 
 performed by one or another with some peculiar 
 advantages, which though singly of little importance, 
 would by conjunction and concurrence open new 
 inlets to knowledge, and give new powers to 
 diligence." To discard all mystery and quackery, 
 and clearly to disclose every process, certainly will 
 be to invite the attention of men of science and 
 research, to extend as far as possible any advantage, 
 however gained, and to discover greater utility in 
 the numerous and various substances employed. 
 And, by the union of varied talent, by unremitted 
 investigation, with perseverance and acuteness in the 
 successive experiments being connected unto com- 
 prehensive and systematic views, we shall have the 
 beau ideal of what it is proper should be our Manu- 
 facturers. May they emulate Davy and Dalton in 
 their bold and sedulous attempts to discover what 
 has hitherto been concealed ; and Bergman and 
 Berzelius in their close and systematic reasonings 
 from causes to results, and vice versd. How truly 
 applicable is this remark : " My intention is, to 
 elucidate clearly the theory, and occasionally the un- 
 philosophical practices, of the Manufacture. Those 
 scientific details which now terrify the adult Manu- 
 facturer, will be mere trifles to his children, when 
 they shall be taught at School a little more 
 Mathematics, and a little less Latin ; a little more 
 Chemistry, and a little less Greek." DUMAS. 
 
[17] 
 
 LABOKATOKY AND APPAKATUS. 
 
 THE Art of Chemical Analysis consists in a most 
 cautious and acute investigation of the structure, and 
 the reciprocal actions and re-actions of substances. 
 Professor Robison justly remarks : " Every change 
 in the state of things is considered as an effect, indi- 
 cating the agency, characterising the kind, and 
 measuring the degree of its cause." And you are 
 aware, that to closely examine these, and all the other 
 categorical particulars of those subjects obvious to 
 the senses, and controlled by the Laws of Nature, 
 there has been successfully employed numerous 
 illustrative experiments, at the expense of great 
 labour, much scientific application, and extraordinary 
 mental and bodily activity. Hence the utility of a 
 Laboratory and Apparatus. 
 
 The LABORATORY, or apartment in which are 
 pursued chemical investigations, must have a dry 
 floor, and a temperature of 60 Fah. to prevent 
 injury to any of the contents. It must be entirely 
 free from the direct solar rays, and influx of dust, 
 of persons passing through, or any disturbance by 
 shocks of machinery. The window must easily open, 
 and the chimney allow space for compounds while 
 offensive gas escapes. In front of the window must 
 be a strong table, with drawers for utensils, yet allow 
 the person to sit close without inconvenience. In a 
 retired part of the room fix a set of double shelves, 
 the upper of each pair thin and pierced, to receive 
 the phials of acids and re-agents, and preclude 
 
18 CHEMISTRY OF POTTERY. 
 
 accidental overturning. In another place fix a set 
 of single shelves. 
 
 The articles of APPARATUS used in the analysis of 
 the different materials of the manufacture, are fewer 
 in number, and less expensive, than for preparing 
 the different kinds of gas. These are indispensable : 
 
 Phials for acids and re-agents, strong, broad, short, and 
 stoppered six each of 8, 4, and 2 oz., and twenty-four 1 oz. 
 
 Phials with wide mouth for dry re-agents and preparations 
 six each of 8 and 4 oz., and twelve of 2 and 1 oz. 
 
 Close-covered earthenware jars, 36s. to 18s., for ores, salts, etc. 
 
 Plenty of all sizes of corks, and of lengths of glass tubes. 
 
 Very small funnel, glass, ribbed ; larger of earthenware. 
 
 Watch glasses, and porcelain capsules ; several sizes. 
 
 Glass jars for mixtures, and three sizes for precipitation. 
 
 Graduated half -pint glass measure. 
 
 Two Woulfe's bottles, and several oil-flasks. 
 
 Iron and porcelain mortars, three sizes. 
 
 Hessian and small porcelain crucibles. 
 
 Platinum crucible, capsule, spoon, forceps, and foil. 
 
 Spirit-lamps, large double wick, and small single wick. 
 
 Blow-pipe and lamp. Platinum, copper, and iron wire. 
 
 Good scales ; cup set, and grains box of weights. 
 
 Flat files, four sizes and cuts ; rat-tail files, four sizes. 
 
 Four sorts of lead shot, mixed, one pound. 
 
 The quantities of the respective substances have these propor- 
 tions : Distilled water, as much as possible (readily procured 
 from condensing steam at any throttle- valve of a steam-engine). 
 The purest is thus prepared into a retort put a pint of clear rain- 
 water ; distil over a little, and with it wash the receiver ; then distil 
 two-thirds of the remainder, and preserve for use. Alcohol, 4 
 oz. very pure, and weaker for the lamp (unless pyro-acetic spirit 
 be used). Pure concentrated Sulphuric, Muriatic, and Nitric 
 Acids, 2, 1, and | Ib. Potash, oz., solid, dissolve in dis- 
 tilled water (always to be understood), let it repose twenty-four 
 hours, then decant into its own phial, and let the stopper be well 
 rubbed with tallow. Always abstract it by the dropping tube, 
 never pour it out, its action on animal and vegetable substances 
 
LABORATOKY. 19 
 
 being so extremely violent. Liquid Ammonia, 4 oz., keep well 
 secured from air and warmth. Garb. Potash, 4 oz., ignite the 
 bicarbonate crystals in the platinum crucible over the double 
 lamp, then dissolve the calc in water, filter, and keep for use. 
 Garb. Soda, dissolve in distilled water, filter, evaporate till a 
 pellicle forms, and place aside to crystallise for the blow-pipe 
 processes ; also, dissolve in water, filter, and preserve for use. 
 Carbonate of Ammonia, dissolve in water, filter, and keep cool and 
 well secured. Nitrate of Silver, \ oz., keep in a dark place. An 
 ounce of each of these crystals, Tartaric Acid, Citric Acid, Sul- 
 phate of Potash, Sulphate of Soda, Yellow Prussiate of Potash, 
 Nitrate of Potash, Sulphate of Copper, Acetate of Lead, Borate 
 of Soda, Sulphate of Magnesia, Alumine, Iron, Soda, Tartrate 
 of Soda ; half an ounce of these crystals, Oxalic and Boracic 
 Acids, Chloride of Barium, Super-oxalate of Potash, Oxalate of 
 Ammonia, Carbonates of Barytes and Magnesia ; and a quarter of 
 an ounce of these, Nitrate and Acetate of Barytes, Phosphate of 
 Soda, and Chromate of Potash. 
 
 For purposes of amusement, these, as sold by respectable 
 druggists, will answer ; but for the researches which require the 
 most scrupulous accuracy, the re-agents must be as pure as 
 possible, and preserved in well-stoppered (not corked) phials, 
 else something may enter, or escape, and spoil them. The 
 crystals, in small portions, must be pulverised and dissolved, 
 then filtered, and always saturated, transparent, and without 
 deposit, except of its own crystals, as when used, a drop or 
 two of distilled water will readily dilute. The solutions which 
 separate spontaneously are to be made at the moment wanted. 
 
 Test-papers. Take two sheets of very thin yellow-wove post 
 paper for each of the three kinds, and after being immersed and 
 dried, cut into squares of two inches broad ; then keep well 
 secured from light, air, and vapours, and each square cut into 
 six or eight strips for use. 
 
 In a pint of distilled water, boil 1 pound of red cabbage leaves 
 in shreds till all the colour is abstracted ; strain through muslin, 
 evaporate to half a pint, pour into a shallow dish, immerse the 
 paper ; afterwards with alcohol odourate the liquid in a well- 
 secured phial. Of Litmus and Turmeric, each J oz. Logwood 1 oz., 
 and a quarter of a pint of water, boil half an hour in a bowl, strain 
 through muslin, and proceed as directed for the cabbage-leaf paper. 
 
 02 
 
20 CHEMISTRY OF POTTERY. 
 
 Most chemical preparations are deleterious, and must not be 
 trifled with. Many of them burn whatever they touch, the fingers, 
 or clothes, and this can only be prevented by care in using the 
 phials : wet the stopper with the liquid, then withdraw it, and 
 make a line on the rim of the phial, to which wet line apply the 
 stopper, and let the liquid escape only in drops till all is obtained. 
 Let every preparation be placed on the shelf, to prevent its 
 injuring any person ; and also be distinguished by its label, and 
 its own place, to save time and diminish the trouble inseparable 
 from the study. 
 
 The Jars for the Laboratory should be so formed that the 
 cover can sink down and rest on a ledge in the flange. When- 
 ever any substance is to be kept in such jar, free from air, the 
 only addition needed is a little hog's lard on the ledge round, and 
 more to be applied when the cover is in its place, so that it can 
 be readily removed, and yet will always be air-tight. 
 
 The preparation of the Re-agents, or Tests, when- 
 ever possible by the student, is peculiarly useful and 
 beneficial. Certainly they can be obtained at much 
 less expense than that of preparing them ; but I 
 believe very few will estimate the mere purchase and 
 application above the knowledge resulting from their 
 preparation. By conforming to all the directions, 
 examining every appearance and product, remarking 
 the relative active or sluggish energies of the respec- 
 tive substances, there are acquired dexterity in using 
 the apparatus, confidence in the genuineness of the 
 re-agents for future researches ; and more real infor- 
 mation is obtained by observing all the phenomena 
 presented by merely one experiment, than can pos- 
 sibly result from a partial attention to several. What- 
 ever difficulty occurs, the greatest are those of false 
 notions, which have to be superseded by others new 
 and correct ; and afterwards the details of processes 
 
NAMES OF PKOCESSES. 21 
 
 are more readily comprehended, and the pursuit of 
 the science in a considerable degree facilitated. 
 
 For convenience, the several operations in Analysis 
 and Synthesis the separation of, some and the join- 
 ing together of other elements or compounds have 
 distinctive appellations ; as Ignition, all its particles 
 being red by heat ; Fusion, melted by heat, the con- 
 trary being infusible ; the application of heat in fusion, 
 chemically changing a solid into a fluid substance, 
 as Metals and Salts, which latter have the aqueous 
 peculiar, because of water of crystallisation pre- 
 sent and the igneous, solely from action of heat. 
 Solution, separation in a liquid ; and when not 
 so separable, insoluble. Whenever the combinative 
 potencies of the elements in the fluid exceed those of 
 the elements in the solid towards each other, solution 
 begins, and continues till amongst these potencies 
 there is equilibrium ; the solvent potency of the fluid 
 is counterbalanced, the solution is saturated, and any 
 excess of the solid remains unaffected. Decomposition, 
 the separation of components by heat and galvanic 
 action (its unphilosophical application to separation 
 in fluids, where fresh compounds result, should be 
 discontinued). Evaporation, by heat dissipating all 
 the volatile particles of a fluid compound, and pre- 
 serving all the fixed, in shallow open vessels, with 
 regulated temperature, and either increased or dimi- 
 nished atmospheric pressure, as the volatile and the 
 fixed particles have more or less difference in their 
 tendency to be dissipated. Usually, the elements in 
 the evaporated fluid aggregate in beautiful crystals, 
 with regular and determined form of sides and angles, 
 similar to the masses, and cut in the same figure as 
 
22 CHEMISTEY OF POTTERY. 
 
 those by nature ; a regularity which proves that the 
 fiat for their formation is not blind chance or for- 
 tuitous motion, but the will of an Omniscient and 
 Almighty Creator. Distillation, separating all volatile 
 particles, and collecting and preserving them at a 
 reduced temperature, as liquids. Precipitation, sepa- 
 rating one element of a compound fluid by changing 
 the condition and circumstances. When this com- 
 pound has two components (as acid and oxide) 
 besides water, on exhibiting a third (as an alkali), 
 which solicits one of them more potently than they 
 solicit each other, either the fresh compound, or 
 that component which does not enter into the fresh 
 compound, as they happen to be, relatively, more 
 or less soluble, separates from the menstruum or 
 mother-liquor, and precipitates to the bottom of the 
 vessel. When the proportions of the components of 
 the fresh compound are so adjusted that neither is 
 in excess, they are in equivalence; and when the 
 liquid does not alter the tint of the test-papers, it 
 is a neutral salt. Filtration, obtaining what was 
 separated in a solid state. A speedy process of 
 mechanically separating the fluid portion of a com- 
 pound from the solid, whether accidentally mixed 
 with it, or a precipitate, by a re-agent affecting the 
 fluid compound. It is accomplished several ways, 
 by sponge, tow, wool, cotton, and for corrosive fluids, 
 fine glass powder in an inverted phial ; but the 
 general practice is unsized cap paper, or common 
 blotting paper, at times supported by linen cloth, 
 through which the fluid permeates and escapes, 
 while on the paper remain the solid particles, to be 
 washed, dried, and preserved for examination or 
 
NAMES OF PKOCESSES. 23 
 
 future use. The employment of lawm, in the manu- 
 facture, is a kind of nitration. In some processes, 
 repose for a length of time is preferable to nitration, 
 as in preparing the Purple of Cassius. In such pro- 
 cesses let a strip of coarse linen rag be made wet, 
 and one end be immersed in the middle of the preci- 
 pitate, while the other is carried below the support of 
 the vessel, on the principle of the siphon and capillary 
 re-action ; all the water will be gradually conveyed 
 away, and every atom of the powder will be pre- 
 served. Calcination, dissipating, by heat, some of 
 the elements of substances, whether incombustible or 
 not, which if present would preclude the chemical 
 combination of the fixed residue with other substances 
 to form fresh compounds ; thus the water of crystalli- 
 sation is dissipated from borax, alum, gypsum, etc., the 
 volatile components of bones (ammonia) is evolved, 
 and the results are the cinders of common language, 
 and the calcs, or oxides of chemical nomenclature. 
 Elutriation, washing off lighter particles, leaving the 
 heavier to subside. Eliquation, fusing only the more 
 fusible of two metals. Granulation, subdividing for 
 facile chemical action a melted metal, by pouring it 
 from some height either into cold water, or a box 
 whose sides are well chalked, and kept in motion till 
 it congeals, when it becomes a fine powder. Cemen- 
 tation, placing a solid body in the powder of another 
 body, and then in a close vessel subjecting the whole 
 to a temperature just below that at which the con- 
 tents would fuse. The baking of biscuit Porcelain in 
 flint powder is a kind of cementation. Trituration, 
 rubbing substances extremely fine in a mortar, porce- 
 lain, or agate ; but its results are always coarse and 
 
24 CHEMISTRY OF POTTERY. 
 
 wasteful, compared with those from Levigation, the 
 scientific name for grinding on a flat stone, hard, 
 polished, and lubricated with water, oil, or turpen- 
 tine. The substance is gradually and constantly 
 reduced in the size of its particles by the motion of 
 a stone moved by the hand, and called the muller. 
 Its face being flat and polished, while the fluid pre- 
 vents the particles fleeing around, the action and re- 
 action facilitate the comminution. The palette-knife, 
 or bone spatula, readily brings and keeps all the mass 
 together. Sublimation, by heat separating the vola- 
 tile particles of solid bodies, and again obtaining 
 them in a solid form, in which restriction to solids 
 it differs from evaporation. It as well purifies the 
 substance from extraneous or deleterious ingredients 
 as vapourises, and in that very comminute state con- 
 fines principles which else would not easily have 
 united. All fluids being volatile by heat, and there- 
 fore in most instances separable from fixed matters, 
 hence, various solid substances are subjected to a 
 similar process. Fluids distil, solids sublime ; and 
 sometimes both are results of one and the same pro- 
 cess. Substances not volatile per se, usually can be 
 rendered so by the presence of others ; and often in 
 close vessels the fumes rise only a little, and adhere 
 to the part where they concrete. The result, when 
 powder, is flowers ; when solid, a sublimate. 
 
ELEMENTS. 
 
 ALL the wonderful diversity of objects presented 
 by nature, and recognised by the senses, are either 
 simple ELEMENTS, remaining the same to whatever 
 chemical processes subjected only fifty-four being at 
 this day known (1836) or, compound, BODIES or 
 substances, the reciprocal action and recipience of 
 rarely more than seven, and often only three or four 
 of the former, into which, by such processes, they are 
 separable. Repetition of the processes, not reason- 
 ing a-priori, has determined this, although, from 
 knowing all their distinguishing characters, we are 
 precluded by the impossibility of exhibiting even 
 any one of the former to all the others, in every 
 possible variation of temperature and atmospheric 
 pressure. 
 
 All language consists of words, of a small num- 
 ber of letters, variously arranged, to faithfully depict 
 the sounds of the human voice, and only a few some- 
 times stand alone. For their analysis human intellect 
 is by some supposed inadequate ; yet the solution 
 of this difficult problem is the signs for Letters, 
 Syllables, and Words, in different languages, and 
 for stenography and music. The analysis of the 
 Principles of the mysterious science the Black Art 
 Chemistry, has hitherto been expected on some basis 
 or other, chiefly by those who study the science only 
 because they may not dispense with it ; while the 
 secrets hidden in the dark abyss of nature cause 
 others of superior minds, and intent on understanding 
 what is known, to confess the inefficiency of current 
 
26 'CHEMISTEY OF POTTERY. 
 
 processes to develop these Principles ; and they 
 remain satisfied with the probable composition of 
 Bodies. 
 
 Each of the fifty-four Elements, or undecomposed 
 substances, has an essential peculiarity for uniting 
 with the others. This, when presented in an abstract 
 or separate form, in the requisite comparison of 
 momenta with ratios of numbers assigned to all, has 
 often been called its Electricity ; and when a com- 
 pound of any of four (oxygen, chlorine, iodine, and 
 fluorine, which very powerfully solicit all others) 
 with any one of the remainder, is subjected to the 
 action of the galvanic circuit, and decomposed, this, 
 remarkable difference is observed : at the positive or 
 active pole the oxygen, etc., concentrates ; and the- 
 hydrogen, metals, etc., at the negative or recipient. 
 Thus are clearly distinguished the agent and patient 
 as the Elements of the decomposing compound con- 
 centrate at the positive and the negative poles. 
 
 With this restriction to the active or sluggish mo- 
 mentum, the qualities of positive and negative are 
 attributed to the respective elements ; although only 
 the two extremes of the Series following (copied from 
 Mr. Griffin's Chemical Recreations) are without both 
 kinds of momenta, active, communicative, positive 
 with regard to all below, but, to all above, quiescent,, 
 receptive, or negative. 
 
 The following table shows, 1. The names of all 
 the chemical Elements, arranged in the order of their 
 relative decomposing powers. 2. The weights of the 
 atoms of the Elements, determined by a method 
 described hereafter. 3. Symbols, and 4. Names r 
 for denoting the atoms of the elements. 
 
ELEMENTS. 
 
 27 
 
 < + , 
 
 Weight 
 of an 
 Atom. 
 
 Symbol 
 of an 
 Atom. 
 
 Name 
 of an 
 Atom. 
 
 
 Potassium 
 
 10 
 
 K 
 
 Kali 
 
 
 Sodium 
 
 6 
 
 N 
 
 Nati 
 
 
 Lithium 
 
 1-5 
 
 L 
 
 Liti 
 
 
 Barium 
 
 17-5 
 
 Ba 
 
 Bari 
 
 
 Strontium 
 
 11 
 
 Sr 
 
 Stroni 
 
 
 Calcium 
 
 5 
 
 Ca 
 
 Calci 
 
 
 Ammonium 
 
 4-5 
 
 Am 
 
 Ammi 
 
 
 
 
 Magnesium 
 
 3 
 
 Mg 
 
 Magi 
 
 
 Numerical 
 
 
 Glucinum 
 
 4-5 
 
 Be 
 
 Beri 
 
 
 exponents, 
 
 
 Yttrium 
 
 8 
 
 Y 
 
 Yttri 
 
 
 or names 
 
 
 Aluminum 
 
 2-25 
 
 Al 
 
 Ali 
 
 
 denoting 
 
 
 Zirconium 
 
 5-5 
 
 Zr 
 
 Ziri 
 
 
 any number 
 
 
 Thorium 
 
 15 
 
 Th 
 
 Thori 
 
 
 of atoms up 
 
 
 Manganese 
 
 7 
 
 Mn 
 
 Mani 
 
 
 to 12. 
 
 
 Zinc 
 
 8 
 
 Zn 
 
 Zinki 
 
 
 
 
 Cadmium 
 
 14 
 
 Cd 
 
 Cadi 
 
 
 1 mona 
 
 
 Iron 
 
 7 
 
 Fe 
 
 Feri 
 
 
 2 = dia 
 
 
 Nickel 
 
 7 
 
 Ni 
 
 Nicki 
 
 
 3 = tria 
 
 
 Cobalt 
 
 7 
 
 Co 
 
 Gobi 
 
 
 4 = tetra 
 
 
 Cerium 
 
 11-5 
 
 Ce 
 
 Ceri 
 
 
 5 = penta 
 
 
 Lead 
 
 26 
 
 Pb 
 
 Plumi 
 
 
 6 = hexa 
 
 
 Tin 
 
 14-5 
 
 Sn 
 
 Stani 
 
 
 7 hepta 
 
 
 Bismuth 
 
 18 
 
 Bi 
 
 Bisi 
 
 
 8 = octa 
 
 
 Uranium 
 
 35 
 
 U 
 
 Uri 
 
 
 9 = enna 
 
 
 Copper 
 
 8 
 
 Cu 
 
 Cupri 
 
 
 10 = deca 
 
 
 Silver 
 
 27-5 
 
 Ag 
 
 Argi 
 
 
 ll = endeca 
 
 
 Mercury 
 
 25 
 
 Mr 
 
 Meri 
 
 
 12 = dodeca 
 
 
 Palladium 
 
 6-5 
 
 Pd 
 
 Palli 
 
 
 
 
 Platinum 
 Rhodium 
 
 12-25 
 6-5 
 
 Pt 
 R 
 
 Plati 
 Rhodi 
 
 
 -r j 
 
 1 OOK 
 
 TV 
 
 T " 
 
 
 xria.iu.ni 
 Gold 
 Osmium 
 Hydrogen 
 Silicium 
 
 16-5 
 12-5 
 25 
 2 
 
 ir 
 Au 
 Os 
 H 
 
 Si 
 
 Auri 
 Osmi 
 Hydri 
 
 Silli 
 
 
 p signifies the 
 positive ele- 
 ment in ex- 
 
 
 Titanium 
 
 3 
 
 Ti 
 
 Titi 
 
 
 cess to the 
 
 
 Tantalum 
 Tellurium 
 Antimony 
 Carbon 
 Boron 
 Tungsten 
 Molybdenum 
 Vanadium 
 
 15 
 8 
 11 
 3 
 1 
 8 
 12 
 17 
 
 Ta 
 Te 
 Sb 
 C 
 B 
 W 
 Mo 
 V 
 
 Tani 
 Teli 
 Stibi 
 Cari 
 Bori 
 Woli 
 Moli 
 Vani 
 
 
 extent of 1 
 atom, if not 
 otherwise 
 mentioned 
 n signifies the 
 negative 
 element in 
 excess to the 
 
 
 Chromium 
 Arsenic 
 Selenium 
 Phosphorus 
 
 7 
 9-5 
 10 
 
 4 
 
 Cr 
 
 As 
 Se 
 P 
 
 Cromi 
 Arsi 
 Seli 
 Phosi 
 
 
 extent of 1 
 atom, if not 
 otherwise 
 mentioned. 
 
 
 Fluorine 
 
 4-5 
 
 F 
 
 Fluri 
 
 
 
 
 Iodine 
 
 32 
 
 I 
 
 lodi 
 
 
 Bromine 
 
 20 
 
 Bm 
 
 Bromi 
 
 
 Chlorine 
 
 9 
 
 Cl 
 
 Chlori 
 
 
 Azote 
 
 3-5 
 
 Z 
 
 Zoti 
 
 
 Sulphur 
 
 4 
 
 s 
 
 Suli 
 
 
 Oxygen 
 
 4 
 
 
 
 Oxi 
 
 
 Water 
 
 4-5 
 
 Aq 
 
 Aqui 
 
 
CHEMISTRY OF POTTERY. 
 
 The Numbers indicate the precise arithmetical 
 proportions, or definite relations of the single atoms, 
 by weight, determined by experiment, examination, 
 and analysis, of the mutual, fixed, and resulting quan- 
 tities, one to another, in which they ever and only 
 form regular compounds. 
 
 It must be understood, that, with reference to the 
 real nature of the Elements, all is conjecture. We 
 assume, however, that each kind of atoms, in accord- 
 ance with Nature's general laws, peculiar in shape or 
 form, with orbital space of determined size, invisible 
 to us, yet included in the general atmosphere. * 
 The atoms of vulgar regard, whose aggregation in a 
 determined space constitutes density and weight, are 
 
 *The French mathematician, Poisson, has calculated the 
 manner in which Electricity, or, in fact, these orbital spaces, may 
 exist, and be affected. From his remarks I have selected the 
 following as most pertinent, adapting my own language : 
 
 Around each atom is an orbital space, varying in shape and 
 size with those of the atoms ; its thickness at every part depend- 
 ing also upon that shape, yet preserving the equilibrium of the 
 atom. The problem is always reduced to determining the shape 
 of the atom. The quantity is always proportioned to the surface. 
 The thickness in each point of the surface, to preclude irregular 
 action of the atom, must be greatest at the summit of the longest 
 of the three axes, and smallest at that summit of the shortest ; 
 and these also be to each other as the length of the axes. Was 
 the stratum of this orbital space very thin, its distribution round 
 a spheroid will vary little from a sphere. But the varying thick- 
 ness can be estimated by current knowledge only in regard of the 
 spheroid and ellipsoid. Suppose the atom a sphere, the orbital 
 space is equally thick over every part of the surface. Suppose it 
 an ellipsoid, the orbital space would be relatively thick at the 
 extremities of the longer axis, and thin at those of the shorter, 
 and the whole will assume the form of an ellipsoidal shell, the 
 interior surface ever coinciding with the shape of the atom. 
 
ELEMENTS. 29 
 
 those parts of substances which by continued tritura- 
 tion may be reduced smaller and finer, yet retain 
 their characters and relative properties. Chemistry 
 presents others to her votaries, the principles which 
 
 That the reciprocal actions and re-actions of atoms are as 
 the inverse of the square of the distances is demonstrated by 
 the coincidence of calculation with the phenomena. When the 
 orbital spaces of component atoms in a body are undisturbed by 
 supplied or abstracted motions of heat, such body is in its natural 
 state. On adding a determined quantity of one kind of atoms, 
 these with their orbital spaces distribute motions to those of the 
 body, and the whole are alike affected. When two excited atoms 
 are in contact, the point of contact is neutral, or without physical 
 energy ; and the greatest quantity of orbital space is accumulated 
 at the point most remote therefrom. The quantity for each 
 increases from that to the maximum point, according to the re- 
 lative diameters of the two atoms. The thickness being nothing 
 at the point of contact, two spherical atoms, with like momenta 
 in contact, are at this point without action or re- action. Around 
 it, and even to some distance, the momentum is very weak upon 
 each atom, and the expansion small, and where appreciable, it 
 at first is more powerful in the larger atom, and afterwards 
 increases at the greatest rate on the smaller, so as to be upon 
 the point diametrically opposite that of contact, always greater 
 on the smaller atom than in the corresponding point of the 
 larger. When removed beyond all reciprocal solicitation, each 
 separated atom is uniformly surrounded and accompanied by the 
 whole of its orbital space. 
 
 The formula of the action and re-action of spheriods supply 
 data to calculate those of the orbital space for a point in any part 
 thereof. In proportion to its thickness is its re-action in each 
 point of the surface of a spheroid, little differing from a sphere ; 
 and the like regards the surface of an ellipsoid of revolution, 
 whatever be the ratio of its relative axis. In these two shapes of 
 atoms the orbital space would most re-act where was the greatest 
 momentum. La Place has, by synthesis, satisfied mathematicians 
 that always is the re-action proportional to the thickness. We are 
 not certain that it varies at the [surface of atoms in motion, or 
 is proportional to the square of the thickness. Whenever its- 
 
30 CHEMISTEY OF POTTEKY. 
 
 constitute all other substances, and remain unaffected 
 by current processes of analysis.* Although the word 
 atom precludes the idea of half-atoms as absurd, and 
 indicates the smallest imaginable portion of an 
 
 expansion has momentum greater than that of the other atoms, 
 entry and admission of the orbital spaces, especially from pointed 
 or sharp-edged extremities, combination results. 
 
 The analysis applies equally to action and re-action, affecting 
 the same atom at the same instant. Suppose one atom excited 
 only as much as by the atom presented, then the combinative 
 recipience in re-action to that of the great atom, accumulates 
 nigh the least distant point, while nigh its opposite point accumu- 
 lates similar combinative recipience. In these points the recipro- 
 cal potencies are almost equal ; and the line of separation differs 
 little from the grand circle perpendicular to the line which joins 
 the two centres, and equally divides the little atom. 
 
 * Dobereiner thus assumes the different sizes of atoms of 
 gases : In a large glass that had a very minute fissure, hydrogen 
 was left standing over water, and in twenty-four hours the water 
 had risen almost three inches, without any sensible alteration of 
 the barometer and thermometer, and this always occurred when- 
 ever the vessel had fissures, but never when the vessel was 
 covered by a bell-glass, or when filled with atmospheric air, 
 oxygen, or nitrogen. Eegarding all gases as consisting of solid 
 atoms of varied size, enveloped by orbital spaces, as atmospheres 
 of heat and likewise very different, hydrogen, with the smallest 
 atom, has the largest orbital space, or atmosphere of heat, and 
 therefore may escape through fissures which retain the other 
 gases ; as other fissures may allow nitrogen to escape, and yet 
 retain oxygen, others similarly allow oxygen to escape, but retain 
 carbonic acid gas. He mentions also this remarkable probability, 
 that a tube will admit air, yet not admit alcohol : A thermometer 
 tube, finely drawn out by the lamp, to fill with alcohol, had the 
 point immersed, and the bulb heated till no air-bubbles escaped, 
 and yet when cooled, no alcohol entered. Being again heated, 
 bubbles passed out through the alcohol ; still, when cooled, no 
 alcohol entered. The tube through a lens appeared open, and 
 when taken out of the alcohol, the air hissed on entering it. 
 
ELEMENTS. 31 
 
 element, the fancy associates therewith a portion of 
 universal space in which it exists and is movable, 
 and whose diminution or enlargement, contraction or 
 expansion, capacitates it for combination or separation. 
 This is the true cause of what is mentioned in many 
 chemical works as a " natural tendency [in the 
 elements] to approach each other, whatever be the 
 distance at which they are placed ; " although these 
 mechanical effects are, confessedly, efficient only 
 u when [the elements are] placed in apparent contact." 
 The Electricity of the elements is easily explained. 
 Every instance of the mutual action and re-action of 
 
 The oxy-hydrogen microscope of Brown demonstrates the 
 existence of circular or orbital motions in every substance inves- 
 tigated ; and M. Muncke exhibits them by this easy method : On 
 a glass-plate triturate the size of a pin's head of gamboge in a large 
 drop of water ; and in this dip a pin's head, and in another drop 
 of water mix well the fluid taken ; of this take half the size 
 of a millet-seed, suppose O5 of a line, place it under the magnifier 
 of 500 power, and there will appear brownish-yellow points, round 
 and elongated, similar to fine grains of gunpowder, distant from 
 each other 0*25 to 1 line, but all in constant slower or quicker 
 motions, so that they move through the apparent space of 1 line, in 
 from 0-6 to 2" or 3". When oil of almonds is used, these motions 
 do not appear ; but with alcohol they are almost too quick for 
 recognition. 
 
 Suppose that the magnified side is more than 18 inches of water, 
 with particles moving in it, and the motions being proportionately 
 magnified, and all wonder immediately ceases. These motions 
 are governed by the principle of action and reaction, which re- 
 quires, when atoms are solicited, equal space ever to contain equal 
 momentum. To preserve this, they have equable effect, indifferent 
 to their being orbital, as results of reaction on a rectilinear force, 
 and, to the atoms uniting in one orbit, or moving in concentric 
 circles, or continuous rings, or parallel planes, or at right angles. 
 And, however confused the primary motions, orbital motion 
 results from rectilinear motion and resistance. 
 
32 CHEMISTEY OF POTTEEY. 
 
 oxygen and hydrogen, and their combination, pro- 
 duces flame and light. Heat presents the excited 
 spheres of light, changes, and decompositions the 
 union of oxygen with the excited hyrodgen of a com- 
 bustible, producing fire and flame ; and Electricity 
 exhibits the excited atoms with expanded orbital 
 spaces, destructions and dispersions the oxygen 
 and hydrogen separated, yet in energy again to be 
 reunited. The respective excitements thus differ : 
 the excited hydrogen in flame needs carbon when 
 oxygen localises the electrical result; but in the other 
 the pure oxygen and hydrogen are separated from the 
 circumbounding space, and artificial obstruction is 
 interposed to delay the constantly solicited combina- 
 tion. How remarkable is the fact concerning hydro- 
 gen and oxygen, which in our day are known each to 
 solicit and be solicited by the other as antagonist 
 principles, that the idea of there being two such prin- 
 ciples, whence originate all other substances, was 
 entertained in a period long anterior to the doctrine 
 of their being four Elements. But the simplicity and 
 perfection of nature astonish us. Like every other 
 result of infinite wisdom, the ground-work is plain 
 and simple, the super-structure noble and magnifi- 
 cent, the causes few and efficient, the effects innu- 
 merable and complete, the course most easy and 
 direct, the means the fewest possible to accomplish 
 the design, surprisingly varied, constantly uniform ; 
 the processes manifest or less obvious might induce 
 a search for multifarious causes, only for the satisfac- 
 tory simplicity of the first principles. 
 
 Who can with indifference behold the subtle ty ? 
 the minuteness, and the perfection of the mysterious 
 
ELEMENTS. 33 
 
 union of the elements into compounds with Protean 
 figures because of varied proportions. Who, arrived 
 at manhood, imagined in his boyish days, or heard 
 mention, that water, light, and heat are different 
 quantities of only the same two elements ; that the 
 substances called Earths are metallic oxides; that our 
 table-salt and nitre are strictly compounds of soda 
 and muriatic acid, and of potash and aqua fortis, 
 each so entirely unlike either of the components. 
 That on the compounds presented by nature com- 
 binative potency confers durability, indestructible 
 by ordinary circumstances ; while all devoid of these 
 characteristics are evanescent, accidental, or only the 
 productions of the laboratory. These discoveries, and 
 all others in this interesting science, arise from the 
 principle of separation, or analysis, by motions of 
 the atoms in heat, or by a third, mechanically intro- 
 duced, uniting with one of those previously present 
 at the precise instant of separation, the required 
 element being left disconnected, to be investigated 
 and employed. 
 
 " All the Processes and Manipulations of the 
 Science (Sir R. Phillips says) resolve into this law : 
 The leverage of sharp tools is not sufficiently fine to 
 change, condense, expand, and convert substances ; 
 therefore, their atoms are by motion heated, or by 
 heat set in motion ; and their relations being dis- 
 turbed, they separate, or decompose. The motions 
 may be affected by figures and densities ; but the 
 atoms being once affected, heat is evolved ; " " for," 
 says Davy, " the laws of the communication of heat 
 are precisely those of the communication of motion. 
 
 D 
 
34 CHEMISTRY OF POTTERY. 
 
 And only does the motion of heat pass through bodies 
 after it has put all their atoms into uniform motion." 
 The task is not very easy to develop and deter- 
 mine the problem by the processes of Chemistry to 
 quickly produce results which, by those of nature, 
 need an unknown period of time. Many substances, 
 with external differences apparently complete, present 
 common characters, by which we trace transition 
 from one to the other. The investigation of the 
 properties of substances or components is productive 
 of advantage ; every step in the inquiry extends the 
 limits of the prospect, and is rewarded with enlarged 
 ideas. We constantly regard a regular succession of 
 general causes as producing uniform results ; and 
 rather than question these, even occasional inter- 
 ruptions of the order and continuity of the series, we 
 refer to particular circumstances. We know only 
 few of Nature's agents, and few principles to explain 
 them ; yet their difficulty of comprehension should 
 render us more scrupulously attentive to their inves- 
 tigation ; and sound philosophy demands that we 
 admit phenomena we cannot explain. Increasing 
 additional proof of the admirable and truly grand 
 simplicity of Nature is the most obvious fact that 
 she conducts us most directly to discoveries, when 
 she presents facts wholly opposed to our opinions. 
 
COMBINATIVE POTENCIES OF ELEMENTS. 
 
 EACH of the elements respectively has combina- 
 tive potency, always proportional to the momentum 
 consequent on change of state, as either agent or 
 recipient. In these states two elements always 
 produce a compound, the communicative and re- 
 ceptive potencies being ever equal and opposed, one 
 never exceeding the other, because no portion of the 
 property must be unappropriated. 
 
 No kind of element, or of substance, per se, has, 
 or can have, active potency. Potency is matter 
 in motion; and, quantity being alike, potency and 
 motion are convertible terms ; for all potency is 
 transfer, or concentration, in the direction of prior 
 potency; and when we say that an element has 
 potency, we mean that it has motion, and vice versd ; 
 the cessation of motion, or indifference to potency, 
 being quiescence or neutralisation. Indeed each 
 of the elements, as all matter, is essentially inert, 
 without potency, except mechanical, derived and 
 connected, with equal and similar origin, process, 
 and results ; and whose complicate, involved, and 
 only efficient momenta produce all phenomena. 
 
 Chemical research hitherto has failed fully to 
 develop the true cause, why, in all matter, however 
 comminute the particles, each of the component 
 elements has a peculiarity, probably as varied as 
 themselves, to receive and sustain a certain mo- 
 mentum of combinative potency towards each other, 
 
 causing the chemical formation of compounds or 
 
 D 2 
 
36 CHEMISTRY OF POTTEEY. 
 
 bodies. And yet, apparently to envelop in mystery, 
 ignorance of the general facts, and whether the 
 effects are, or not, results of difference in the con- 
 formation, have been employed mere poetical figures 
 of speech, the unphilosophical and occult terms, 
 Attraction, Affinity, and Repulsion. 
 
 To calculate phenomena and results correctly we 
 need certain knowledge of the sum of these varied 
 reciprocal momenta. Morveau, Kirwan, and Ber- 
 thollet failed to solve the problem. Yet the patient 
 exercise of common sense, the aid of mathematics, 
 and the laws of mechanics, now demonstrate that 
 they all are mechanical effects in an arithmetical or 
 geometrical series. Motion implies as well as effects 
 some alteration of the combinative potencies ; but 
 their momentum, communicative or receptive, and 
 much varied in degree, as active or sluggish, always 
 equals that of a single atom of each component 
 element, multiplied by the sum. 
 
 The science assumes that bodies are compounds 
 of at fewest two kinds of ultimate indivisible atoms, 
 each kind having a different weight, as already ex 
 hibited, page 28 ; that only do single atoms, and 
 simple multiples of atoms, combine ultimately, while 
 bodies chemically combine proximately ; that only 
 by the principle of ultimate composition can be pro- 
 perly arranged and determined the real characters of 
 chemical products ; and only by that approximate 
 composition are explicable many phenomena of 
 analysis and synthesis. 
 
 The fact is truly remarkable, that every chemical 
 experiment and determination of the most expert and 
 accurate analysts demonstrates this important pheno- 
 
POTENCIES OF ELEMENTS. 37 
 
 menon, that chemical combination is ever the result 
 only of perfect suitability of components, with combi- 
 native potencies that have momenta ever immutable 
 and invariable to form like compounds through all 
 nature, whenever affected by the addition or diminu- 
 tion, the more or less, of motion, than previously 
 existed. Every perfect artificial, as well as every 
 natural body, is composed of various elements having 
 varied momenta towards each other necessarily the 
 results of their communicative and receptive poten- 
 cies being appropriated, with arithmetical precision, 
 and mechanical order; or, of compounds, with 
 these reciprocal characters, affected usually by 
 altered temperature, and possessing chemical proper- 
 ties different from those of either component alone. 
 Every compound which has one element in common, 
 and even its smallest particle, when combining with 
 any other substances, so combines as to contain of 
 this common element certain restricted or Definite 
 Proportions, either equal weights, or one, two, three, 
 four, or more multiples of the primary weight, and 
 only in such proportions. 
 
 This principle, first developed by a Dublin chemist, 
 Mr. Higgins, by Bergman, Kirwan, and Wenssell, 
 and perfected by Eichter, Berthollet, Wollaston, and 
 Dalton, and so followed up by Fourcroy, Chaptal, 
 Davy, and Thomson, has made us intimately ac- 
 quainted with the ratios of the weights of the eleme- 
 tary components of many hundred compounds. 
 
 Why these combinations must be thus in multiples 
 there is only conjecture. Was each elementary atom 
 a solid sphere with an orbital space, compound 
 
dtt CHEMISTRY OF POTTERY. 
 
 particles might have other shapes, without contact 
 of the solid atoms ; while the orbital spaces might 
 be affected by the supply or lack of the motions of 
 heat. Also, was a limited space partially filled with 
 atoms, or particles, whose interstices would admit 
 others of various size, figure, and momenta, it is 
 clear that these atoms must be in only relative num- 
 bers with determined though different forces, the 
 compound being governed by their respective sizes. 
 
 The chief and grand secret of the Analyst being 
 correct knowledge of Combinative Potencies in his 
 processes to combine or separate elementary com- 
 ponents, I consider that it cannot be too clearly 
 explained and elucidated. 
 
 The poles of the galvanic circuit have fully 
 exhibited the ratios of the momenta of combinative 
 potency in each element. The difference of the 
 atomic motions, of particles at sensible distances, 
 and of atoms at insensible distances, as communicative 
 and receptive, are the causes of combination being 
 rapid or sluggish. 
 
 The following have been considered the laws of 
 potency, and additional remarks will show how 
 they apply : 1. Combinative potency is efficient only 
 and ever when dissimilar substances or elements are 
 placed in contact. 2. This is most rapid when the 
 substances are extremely comminute. 3. This is 
 promoted when a fluid is present. 4. This may 
 affect two or several elements or substances. 5. 
 This is always accompanied by altered temperature. 
 6. This produces compounds different from either 
 component. 7. This has momenta exceeding those 
 
POTENCIES OF ELEMENTS. 39 
 
 of the components, and causing precipitates. 8. This 
 differs in different substances. 9. This is limited 
 in certain substances.* 
 
 Water solicits and separates the elements of more 
 substances than any other fluid at temperatures be- 
 tween 32 and 212 Fahrenheit. Distilled or pure 
 water most exerts this property, holding the com- 
 ponents separate as little altered as possible. Impure 
 
 * These are exemplified in the following substances : 1. Mu- 
 riatic acid and soda, muriatic acid and mercury, nitric acid and 
 copper, nitric acid 3, water 3, mercury 1 ; lime-water and oxalate 
 of ammonia, solution of muriate of barytes and sulphuric acid, 
 solution of nitrate of lead and sulphuric acid, solutions of muriate 
 of antimony and phosphate of lime in muriatic acid, added to 
 plenty of ammonia and water, acetate of potash 2, sulphuric acid 1. 
 2. Metals in acids, gums in alcohol, alum in water. 3. Citric 
 acid and carbonate of potash dry and in water, tartaric acid and 
 carbonate of soda similarly, nitrate of potash and sulphuret of 
 antimony, mercury and sulphur. 4. Fusible metals, soda, potash 
 and tartaric acid, sulphuric acid, alumine and soda. 5. Alcohol 
 and water, muriate of ammonia and water, sulphuric acid and 
 water, dilute sulphuric acid on iron, equal weights of nitrate of 
 potash and muriate of ammonia in water. 6. Table salt, of chlo- 
 rine and soda, glass of sand and potash, verdigris of acetic acid 
 and copper, vermilion of mercury and sulphur. 7. Solutions of 
 sulphate of iron by that of soda, of nitrate of mercury, or nitric of 
 silver by muriatic acid, of acetate of lead, or muriate of barytes by 
 sulphuric acid, of sulphate of magnesia by that of potash. 8. To 
 solution of nitrate of mercury add fine filings of copper which 
 dissolve as the mercury precipitates, add fine filings of iron which 
 dissolve as the copper precipitates, add zinc filings which dissolve 
 as the iron precipitates, add ammonia and the zinc precipitates, 
 add lime and the ammonia evolves, add oxalic acid and the oxa- 
 late of lime precipitates, leaving the liquid very dilute nitric acid. 
 9. Undetermined water and alcohol, or water and sulphuric 
 acid ; but only a determined quantity of water and salt, alcohol 
 and resin, nitric acid and lime, and muriatic acid and soda. 
 
40 CHEMISTEY OF POTTERY. 
 
 water much affects the substances by admixture of 
 foreign, ingredients. Hence the practical utility and 
 importance of humid chemical analysis of substances, 
 which, by the aid of pure water, presents their proxi- 
 mate components, and often their ultimate elements. 
 It is best procured as the intermediate product from 
 rain-water, rejecting the first and the last products. 
 It is beautifully transparent, colourless, without odour 
 or savour, feels soft, and most readily wets the fingers, 
 and continues clear and limpid when we add the most 
 exquisitely sensible re-agent, as nitrate of silver, solu- 
 tion of oxalate of lime, or of muriate of barytes, and 
 in a silver capsule evaporates without residuum. 
 Free from any accidental soluble component, it has 
 least weight, and remains unaltered however long 
 time kept in well-stopped vessels. Under barome- 
 trical pressure of 29*8 inches, and temperature of 
 60 Fahrenheit, its specific weight being always the 
 same, it is the standard of specific gravity ; and 
 freezing at 32, and boiling at 212, these degrees are 
 the standard for thermometrical division. Next in 
 purity are rain, snow, and ice- waters ; but others 
 may have volatile substances present, as well as 
 soluble solids. 
 
 The trouble of procuring an adequate supply 
 may have prevented its employment in washing the 
 colourific oxides, and grinding of the biscuit and 
 enamel colours used in the manufacture. Yet that 
 their brilliance would be promoted thereby, I feel 
 well convinced ; and its adoption is warranted by its 
 advantage and indispensable presence in every one 
 of the nicer humid chemical processes. 
 
 Substances can be either mixed, or combined, into 
 
POTENCIES OF ELEMENTS. 41 
 
 bodies. Their gross union is mixture ; thus sand and 
 potash, may be mixed, and when solicited by water 
 they will separate without their nature being changed, 
 although that of the solvent is altered ; but supply 
 motion to the atoms by heat, and however either 
 sluggish or active in one state, and the contrary in 
 the other, their most minute particles unite, their 
 elements combine into a body with characters entirely 
 distinct and different from those of either substance 
 and their elementary components, and a prolonged 
 high temperature causes the chemical combination of 
 the sand and potash into glass, which water does not 
 separate. The atoms, not merely the gross masses, 
 being combined more or less readily, and the recog- 
 nised characters of the separate components being 
 changed, the compound is inseparable by any mecha- 
 nical means ; and only can this be effected by the 
 solicitings of heat, acids, or other solvents, when all 
 the components have precisely similar circumstances. 
 
 Because in only few instances solid bodies com- 
 bine, always accompanied by fluidity, chemists usually 
 consider fluidity in one component brought into con- 
 tact as indispensable to chemical phenomena : cor- 
 pora non agunt nisi sintfluida. Certainly the liquid 
 state, or that of gas, is most favourable, because of the 
 opportunity afforded for the full exercise of the atomic 
 motions, co-extensive in the same plane whether ver- 
 tical, concentric, etc., for only in liquids, or gases, 
 have the atoms specific motions, in various degrees 
 opposing the force of mechanical cohesion. Motion 
 is ever opposed to cohesion, and its diminution or 
 absence promotes fixation. 
 
 Gay Lussac first demonstrated that the gases 
 
42 CHEMISTRY OF POTTERY. 
 
 combine by weight, or volume, the components being 
 in either equal number of volumes, or the excess 
 always in some regular multiple, 1, 2, 3, 4, of the 
 primary volume ; thus 1 of ammonia and 1 of 
 muriatic acid form 1 neutral muriate of ammonia ; 
 1 ammonia and 1 carbonic acid form 1 neutral 
 carbonate of ammonia, the weights being as those 
 of the substances employed to form them ; and, 
 consequently, whether combining by weights or 
 volumes, the proportions are definite, and the 
 numbers for the gases are those for their .base. 
 
 When one of the two substances brought into 
 contact, at the temperature of the experiment, is a 
 fluid, the combinative potencies of its elements solicit 
 and separate those of the third substance exhibited. 
 Their momenta differ with the substances, as well 
 as with their elements, and their existence and 
 operation are demonstrated by the solid substances 
 which result from the contact of elements. 
 
 Such fluid is termed a solvent, or menstruum, the 
 mixed liquor a solution, and the solid body dissolved ; 
 and the solution is saturated when a portion of the 
 solid remains undissolved. Yet this saturated solu- 
 tion is passive to only that substance, and frequently 
 has combinative potency with other substances, much 
 exceeding that of the primary fluid. 
 
 When an element is exhibited to a compound, 
 its combinative potency, its varied rapid or sluggish 
 atomic motions, will solicit, or be solicited by, that 
 of one component, or those of both, and there result 
 separation of the former and formation of a fresh 
 compound. When to solution of nitrate of lime 
 we add solution of pure potash, this solicits and 
 
POTENCIES OF ELEMENTS. 43 
 
 combines with the nitric acid, leaving the separated 
 lime to precipitate. 
 
 This has been called simple elective attraction, 
 and also simple affinity, concerning which we may 
 say a few words : All known elements are termed 
 simple, only with reference to current ability to 
 decompose them. What is then the simplicity of 
 this simple elective attraction ? Daily discoveries of 
 contemporaries enable them to separate substances, 
 supposed elements only a few years ago. But, in- 
 dependent of this difficulty, there is present in all 
 humid processes water, whose elements, oxygen 
 and hydrogen, much modify the character of bodies 
 immersed or suspended therein. The variations of 
 temperature, whether by change of form in the sub- 
 stances, mere modification of parts, or communication 
 of the motions of heat, negative the strict application 
 of the designation to any experiment whatever. 
 
 When two binary compounds, or which have each 
 only two elements present, are placed in contact, the 
 separation of each ensues, and they mutually exchange 
 elements, causing the formation of two fresh com- 
 pounds, each with a character different from those of 
 the prior compounds, and of their primary elements. 
 Some saline solutions exchange principles without 
 evident change of properties ; yet change of properties 
 always implies chemical combination. 
 
 Place in contact solutions of nitrate of silver, 
 that is, nitric acid and oxide of silver, also common 
 salt, that is, muriatic acid and soda ; the nitric acid 
 will solicit and combine with the soda, and the 
 muriatic acid similarly with the silver, and two 
 fresh compounds result. Again, saturate nitric acid 
 
44 CHEMISTRY OF POTTERY. 
 
 with oxide of mercury, dilute with pure water, into a 
 dilute solution of nitrate of mercury. Saturate sul- 
 phuric acid with potash, into a solution of sulphate 
 of potash. Add mercury alone to the latter solution, 
 it will combine therewith ; the acid will solicit the 
 metal, yet not separate from the alkali by which it 
 is solicited. In like manner add nitric acid alone, 
 and, although their reciprocal combinative potencies 
 are great, the alkali continues combined with the 
 acid it had previously appropriated. But, mix the 
 two solutions, and immediately there ensue separa- 
 tion and a change of elements ; the sulphuric acid, 
 separated from the alkali, combines with the mercury ; 
 the nitric acid, separated from the mercury, combines 
 with the potash, and by evaporating and crystallis- 
 ing are obtained separately the two fresh compounds, 
 sulphate of mercury, and nitrate of potash. In the 
 process the most remarkable phenomenon is, that 
 the united momenta of the combinative potencies of 
 the sulphuric acid and the mercury, and of the nitric 
 acid and the potash, exceed the sum of those of the 
 sulphuric acid and the alkali, and of the nitric acid 
 and mercury ; and only because the sum of the two 
 last is less, are separated the primary combinations. 
 Nitrate of Mercury 4075, + Sulphate of Potash 
 22 = 6275 ; and Sulphate of Mercury 44 + Nitrate 
 of Potash 25-5 = 69 -5. 
 
 Fluids whose components have combinative poten- 
 cies with equal momenta instantly combine ; while 
 others in which they vary have different times for 
 this purpose, longer or shorter, to separate each other's 
 components, and constitute fresh compounds. The 
 atomic motions are accelerated, or heat is absorbed, 
 
POTENCIES OF ELEMENTS. 45 
 
 when fluids result from dissolving solids ; and dimin- 
 ished, or heat is abstracted, when the substances 
 solidify. In this reaction often do the particles form 
 crystals, whose varied shapes demonstrate the pre- 
 vious peculiar motive power, and different passiveness 
 to the action, or the elastic pressure of the atmosphere. 
 
 When two solid bodies are placed in contact, 
 with combinative potencies as those last mentioned, 
 a fresh compound results. When sulphur and sub- 
 carbonate of potash are brought into contact by the 
 motions of heat, and form liver of sulphur, the two 
 substances may be imagined so extremely subdivided 
 as that only one atom of each combine into a particle 
 of the fresh compound, and chemical sepation would 
 give only the sulphur and the potash. 
 
 When two substances, with equal but opposite 
 potencies, communicative and receptive, are placed 
 in contact, indifference, quiescence, or neutralisation 
 might be imagined from the absence of phenomena, 
 except that a fresh compound results, with characters 
 wholly different from those of either primary com- 
 ponents, and solely by addition of one of those, or 
 a different potency. From this phenomenon is the 
 inference that no results appear, when, to a com- 
 pound, is exhibited a third substance, which solicits, 
 or is solicited by different momenta of those elements, 
 yet superior to that which combines the elements of 
 each particle in the primary components ; but when 
 the potency in either is greater towards this combi- 
 nation, the former two combine, and the other is 
 separated. The change of characters by combination, 
 and of temperature, shape, and colour, ensue, with- 
 out the potencies governing the specific gravity of the 
 
46 CHEMISTRY OF POTTEEY. 
 
 fresh compound, which usually exceeds what would 
 be inferred from those of the primary elements. 
 
 The combinative potencies of elements to form 
 a compound continue while any of them in contact 
 remain unappropriated, unless when one is in 
 excess, as in super and m#-salts. But they must 
 be distinguished from atmospheric pressure on 
 the mass, the power which retains in contact the 
 respective particles, or cohesion. 
 
 Those substances which in all proportions chemi- 
 cally combine with others, or to the point of satura- 
 tion, have weak potencies, all multiples of the first 
 or least combinative momentum, and often the char- 
 acters of the separate components remain distin- 
 guishable ; yet certain relative proportions of water 
 and acid form powerful, permanent, and peculiar 
 compounds. Those Bodies which combine in only 
 one proportion have more momentum, and strong 
 potencies ; the fresh compound is close and deter- 
 mined, and the new characters supersede those of 
 the respective primary components. Likewise, in 
 those bodies which combine in several proportions 
 are these determined, and only these, without any 
 intermediate of the compounds ; and the potencies 
 are multiples of the least momentum. Suppose the 
 least proportion of momentum of B's combinative 
 potency with A indicated by 16, and that of A with 
 B by 24, then A can combine with 32, 48, or 64 of 
 B, but with no intermediate momentum. 
 
 One compound may be a component of another, 
 by a second momentum, and combine in this mul- 
 tiple, or equal momentum, of one of its elementary 
 components, because thereby more potent ; and this 
 
POTENCIES OF ELEMENTS. 47 
 
 fresh compound similarly with a third, and possibly 
 this with a fourth. For, when a compound of two 
 elements, communicative and receptive, is brought 
 into contact with other elements, their potencies are 
 energetic, and all become participant. 
 
 Sometimes a compound of two elements, A B, 
 remains indifferent to the soliciting of the momentum 
 of C's potency, or of D's separately ; but, on exhi- 
 biting their combined momenta, these may exceed 
 those of the former, and cause separation of elements, 
 until the fresh compounds bear that certain proportion 
 to the elementary components which they bear to 
 each other. And when a series of compounds have 
 vsimilar character, and also the same elementary com- 
 ponent, the distinctive nature is usually, perhaps 
 justly, assigned to the potency of that element. 
 
 Suppose two or three different substances, A, B, C, 
 were solicited by another, D, under the same or like 
 circumstances ; then A may combine with B, indif- 
 ferent or sluggish to C and D ; or either C or D may 
 solicit A to separate from B, or vice versd, and a fresh 
 compound ensue. The united momenta of A and B 
 may exceed those of C, yet circumstances may cause 
 C efficiently to solicit A -f B. And, on exhibiting 
 together the momenta of A + B + C, A, B, in equi- 
 valence, often ensue two distinct compounds of B + 
 A, and B + C, agreeably to the proportions present 
 of A and C. When exhibiting C to the compound 
 A B, it may so solicit a portion of the compound, 
 and the remainder may solicit an additional portion 
 of B. Or, C exhibited to A B, may solicit some por- 
 tion of A, and the liberated portion of B may solicit 
 the unappropriated portion of C. The more the 
 
48 
 
 CHEMISTRY OF POTTERY. 
 
 ^compositions the more of B is liberated, and the 
 greater opposing potency against C soliciting A. 
 When the momenta and the potencies are in equili- 
 brium, all phenomena cease of separation and combi- 
 nation. 
 
 The precision of arithmetic must never be warped 
 for theory, and most especially in applying science 
 to the combination of the Earths in this manufacture ; 
 while the numbers themselves are brought very low 
 the better to facilitate the perfection of Analysis and 
 Synthesis. I have been most agreeably surprised 
 that all the Materials for bodies, glazes, and colours 
 have combinative potency whose momentum is some 
 multiple of the number 4, and the strict accordance 
 is not a fancy or conjecture, but indisputable matter 
 of fact. 
 
 Silica consists of 
 Alumine Ditto 
 Magnesia Ditto 
 Lime Ditto 
 
 Barytes Ditto 
 Boracic Acid Do. 
 Manganese Ditto 
 Chrome Ditto 
 Soda Ditto 
 
 Potash Ditto 
 Lithia Ditto 
 
 The principle has never been yet promulgated, and 
 I am ignorant that it has been attempted, although 
 there appears a need for it to be fully investigated 
 and adopted to facilitate correct conclusions, and 
 when mistakes occur to remedy them as soon as 
 detected. When the above numbers are doubled, 
 
 2 
 
 Silicium 
 
 4 + 1 
 
 Oxygen 
 
 4 
 
 = 
 
 8 
 
 2 
 
 Aluminum 
 
 8 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 12 
 
 2 
 
 Magnesium 
 
 6 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 10 
 
 2 
 
 Calcium 
 
 10 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 14 
 
 2 
 
 Barium 
 
 35 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 39 
 
 !fi 
 
 Boron 
 
 2 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 6 
 
 2 
 
 Manganesium 
 
 14 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 18 
 
 2 
 
 Chromium 
 
 14 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 18 
 
 2 
 
 Sodium 
 
 12 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 1G 
 
 2 
 
 Potassium 
 
 20 + 1 
 
 Ditto 
 
 4 
 
 = 
 
 24 
 
 2 
 
 Lithium 
 
 2 + 1 
 
 Ditto 
 
 4 
 
 
 
 6 
 
POTENCIES OF ELEMENTS. 49 
 
 as adopted in Henry, Brande, etc., they are all mul- 
 tiples qf the primary number, determined by repeated 
 and varied experiments. We find Lithia 3 x 4 = 12, 
 Silica 4 x 4 = 16, Magnesia 5x4 = 20, Alumine 
 6 x 4 = 24, Lime 7 x 4 = 28, Soda 8x4 = 32, Man- 
 ganese 9 x 4 = 36, Antimony 11 x 4 = 44, Potash 12 
 x 4 = 48, Barytes 19 x 4 = 76, Lead 26 x 4 = 104, 
 Boracic acid 3 x 4 = 12, Sulphate of Lime, and 
 Phosphate of Soda 15 x 4 = 60, Borate of Barytes 
 23 x 4 = 92. 
 
 Suppose the indices for Silica, Alumine, Mag- 
 nesia, Lime, Barytes, and Manganese respectively 
 be a, b, c, d, e, / and for Lithia, Soda, Potash, Bor- 
 acic Acid, a', b', c, d', their combinative potencies 
 are in strict arithmetical ratios ; the number opposite 
 each respectively indicates precisely the momentum 
 of each when soliciting a' of the second, and b', c', d f 
 the like when soliciting a. Thus the given sum of 
 grains of the first will completely saturate, neutra- 
 lise, or render inert the like number of any of the 
 second. 
 
 Silica 
 
 4x4 = 16 a 
 
 Lithia 
 
 3x4 = 12 
 
 a' 
 
 Alumine 
 
 6 x 4 = 24 b 
 
 Soda 
 
 8x4 = 32 
 
 b' 
 
 Magnesia 
 
 5x4 = 20 c 
 
 Potash 
 
 12 x 4 = 48 
 
 c' 
 
 Lime 
 
 7x4 = 28 d 
 
 Bor. Acid 
 
 12x4 = 48 
 
 d' 
 
 Barytes 
 
 19 x 4 = 76 e 
 
 
 
 
 Manganese 8 x 4 = 32 / 
 
 And because each given quantity of the first series 
 combines with c 48 of the second, its combinative 
 potency is precisely, but only, the same in that quantity 
 as in a' ; and as each of the second series combines 
 with a =16 of the first series, that given quantity 
 
50 CHEMISTRY OF POTTERY. 
 
 of each element has precise equivalence of combi- 
 native force with the assigned sum of that of each of 
 the others in both series ; consequently, any two are 
 in the precise proportions to combine into a regular 
 compound. Whenever in the compound these pro- 
 portions of the elements, or momenta, are thus strictly 
 supplied, the several combinative potencies are neu- 
 tralised. And the numbers for the weight of each 
 component ascertained in any analysis need only to 
 be regarded to understand how nearly will be the 
 results of its combinative potencies to the momenta 
 employed in nature. Also by these numbers can we 
 estimate momenta which would not be exhibited to 
 our observation, like to data in mathematical dis- 
 quisitions. By analysis we are presented with the 
 maxima and minima, the limits of error and degrees 
 beyond which our elucidatory experiments and deter- 
 minations cannot be inaccurate ; and perfect accuracy 
 is the object towards which all our efforts should 
 constantly approximate. 
 
 Every substance is formed of one communicative 
 component and one receptive, each being either an 
 element or a compound. We may be certain that 
 the compound A B is formed of the communicative 
 element A and the receptive element B ; the com- 
 pound A A B of the comparatively communicative 
 compound A B and the receptive element B. But 
 these do not determine nor explain whether in the 
 compound ABC the three elements simultaneously 
 combine, or A B solicit C, or AC solicit B, or A 
 solicits B C ; nor whether in the compound A B C C 
 the elements combine as A + B C C, or A B + C C, 
 orABC + C,orAC + BC, orAAC + BBCCC. 
 
POTENCIES OF ELEMENTS. 51 
 
 We know the elements, and the sum of momenta, 
 A B C, the ultimate composition ; and how they are 
 solicited into proximate composition, science has to 
 develop for her votaries to understand. This very 
 important problem must be carefully solved not 
 conjectured. 
 
 Many deductions of the science have been 
 hastily and only partially drawn, without regard to 
 all the- circumstances which modify combinative 
 potencies. And because of this, although the subject 
 is one of very great importance, up to the time of 
 this going to press there is not published a correct 
 and constant method by which to determine, in any 
 substance, whether an element is present in only one, 
 or in a certain multiple, of its combinative potencies. 
 The remark may not be so palatable as even I might 
 desire ; but truth and duty to my subscribers 
 compel me to declare, that, of the several methods 
 promulgated for this purpose, that by DUMAS is a 
 mere guess-, GMELIN, a perplexity, because of inde- 
 cision ; TURNER, a supposition from an assumption ; 
 D ALTON, an assumption, by experiment proved erro- 
 neous ; THOMSON, a convenient application of the 
 names, neutral salt, atom of acid, and atom of base ; 
 and BERZELIUS, an assumption without proof- atoms 
 of gas, we can measure ; atoms of solids, we can 
 guess. 
 
 Temperature is a most important circumstance 
 in the action of the combinative potencies. Its 
 varied momenta on different compounds are remark- 
 ably obvious in sometimes promoting, and at others 
 preventing, combination ; they always affect, and 
 
 often reverse, the results of combinative potency. 
 
 E 2 
 
52 CHEMISTRY OF POTTERY. 
 
 A notion is prevalent, founded on an hypothesis, 
 but hitherto unconfirmed by direct experiment, 
 that the effects to which I refer are consequences 
 of the materiality of heat. Hereafter it will be de- 
 monstrated (See TEMPERATURE) that it is the supply 
 of motion to the component atoms of the substance. 
 
 Combinative potencies are always alike at the 
 same temperatures, but alter with change of tempe- 
 rature ; for when this is very high the orbital spaces 
 of the atoms are so expanded as to destroy the 
 juxtaposition of the solid atoms which existed while 
 the motions of heat were absent, and no longer is 
 each atom sluggish. I am not prepared to deny or 
 affirm that during these motions from change of 
 temperature the atoms of the components receive a 
 kind of magnetic polarity to reciprocally solicit each 
 other : and that they so concentrate, or intermingle, 
 or disperse, as to produce equilibrium, neutralisation, 
 or chemical combination with the supply, or the 
 withdrawal of the motions of heat. Consequently, 
 combination is more facile among similar than 
 dissimilar substances. 
 
 To a solution of nitrate of potash add alcohol ; 
 at the common temperature, 59 Fahrenheit, it mixes 
 with the water, and the salt is precipitated ; but 
 raise the temperature to 600, and the alcohol will 
 be volatilised, and the salt will be re- dissolved. Add 
 sulphuric acid to a compound of phosphoric acid and 
 lime, at the common temperature ; the compound 
 will be separated, and the phosphoric acid liberated, 
 but the high temperature of this liquid, the combi- 
 native potency of the sulphuric acid, will solicit that 
 of the lime, and separation again ensues : the latter 
 
POTENCIES OF ELEMENTS. 53 
 
 is again solicited to combination with the phos- 
 phoric acid. Raise mercury to the temperature of 
 550 Fahrenheit, from the atmosphere it will solicit 
 and combine with 14 or 15 per cent, of oxygen, and 
 become the red oxide ; but raise the temperature to 
 700, and the oxygen again will resume its gaseous 
 state, and leave metallic mercury. 
 
 The acknowledged imperfections of the science 
 also cause some difficulties. The character of any 
 compound cannot depend more on the nature than 
 on the proportions of its elementary components, 
 for a remarkably small variation in these latter 
 causes a consequent difference in the estimated and 
 valuable properties. Hence the necessity of discri- 
 mination on effects from circumstances like the 
 following : To a compound of two elements exhibit 
 a third element ; its combinative potency varies with 
 the quantity and the relative saturation of the com- 
 pound, or its being most remote possible from those 
 of its separate components. Adding excess of the 
 element, that is, more than its primary quantity, but 
 some multiple, may separate the compound, and also 
 keep soluble both the elements, and thus prevent any 
 precipitate. Again, the compound may have one 
 element in some multiple of its combinative potency, 
 which may solicit or be solicited by the added 
 element, and form a fresh compound, and yet leave 
 a neutral compound, in character much different 
 from the primary compound. Cream of tartar ^is not 
 very soluble in water, and is a compound of potash 
 with excess of tartaric acid. Dissolve some in water, 
 and add some chalk ; the excess of acid will solicit 
 to combination part of the lime of the chalk, and 
 
54 CHEMISTRY OF POTTERY. 
 
 form a scarcely soluble compound. After this 
 appropriation of part of the acid, the remaining 
 neutral compound is very soluble, and has very 
 different taste and properties from those of the 
 cream of tartar. 
 
 The state of oxidation, also, of the acids and the 
 metals much influences resulting phenomena. A 
 determined state of oxidation is needful for the 
 solution of metals in acids, and the acids them- 
 selves have combinative potency in the ratio of their 
 state of acidification. Nitrous acid is superseded by 
 acids weaker than the nitric ; also sulphurous 
 acid by others of inferior combinative potency to 
 sulphuric acid. 
 
 The presence and the quantity of water is of 
 much importance. Bismuth dissolves in nitric acid, 
 yet on adding water precipitates. Mix solutions of 
 muriate of lime and carbonate of soda ; the two 
 compounds separate, and fresh ones result muriate 
 of soda and carbonate of lime. Mix lime and 
 muriate of soda with only water sufficient to form a 
 paste, which submit to a current of carbonic acid 
 gas ; on the surface will be a saline efflorescence of 
 carbonate of soda, and beneath will be muriate of 
 lime in deliquescence. 
 
 The momenta of combinative potencies are in 
 the ratio, not of the primary multiple, but of those 
 of multiples thereof in the quantity employed, for 
 quantity always compensates for weaker potency. 
 Thus one acid with combinative potency less than 
 another for a certain base, by additional quantity 
 solicits and combines with a part of that base, from 
 the acid with greater combinative potency, dividing 
 
POTENCIES OF ELEMENTS. 55 
 
 it between them in the compound ratio of their 
 potency and quantity. This division of one sub- 
 stance between two others always follows the exhibi- 
 tion of three such with mutually energetic potencies. 
 Hence, potency has most momentum when elements 
 are first placed in contact, and this gradually dimin- 
 ishes in one or other as saturation approaches. 
 Also, the great difficulty of the combinative potency 
 of the added element completely separating or 
 freeing a compound from the last portions of any 
 component. 
 
 This is, probably, the real cause of difference in 
 Analysis of the native minerals. Those of Yauquelin 
 differ often from those of Rose, and both from those 
 of Berzelius. The different analyses are useful for 
 two purposes : they teach modesty in determining 
 the precise proportions of components in the second- 
 ary compounds, and also, that to preclude, as far as 
 possible, uncertainty in such researches there cannot 
 be too great attention given in separating the com- 
 pound, to ascertain which component had only one 
 multiple of its combinative potency present ; also, 
 which had more, and how many more, than the 
 primary multiple. 
 
 Again, hasty inferences and deductions have 
 been made from the presence or absence of solubility 
 of compounds at the temperature of the process 
 pursued. Now, in solutions many separations ensue 
 without any precipitate, which only results when the 
 fresh compound, or liberated component, is partially 
 or wholly insoluble in the liquid. Potash can be 
 added to a dilute solution of sulphate of soda, without 
 this latter precipitating, because of the great combina- 
 
56 CHEMISTRY OF POTTERY. 
 
 tive potency of potash for water. But with only 
 a certain quantity of soda and of water to dissolve it, 
 the fresh compound, sulphate of potash, partially 
 soluble, precipitates, instead of remaining suspended ; 
 therefore, only very careful investigation of the 
 results can prove the presence or absence of a 
 precipitate. Sometimes all the components remain 
 suspended, at others all precipitate together : to a 
 solution of sulphate of iron add lime ; this will be 
 solicited to combination by a portion of the acid, and 
 the resulting partially soluble sulphate of lime preci- 
 pitates with the separated and less soluble oxide of 
 iron. Frequently, on exhibiting another substance, 
 there ensue, not separation of components, but 
 equilibrium of momenta, and equivalence of the 
 potencies. In water dissolve cream of tartar (super- 
 tartrate of potash), add soda and it will be solicited 
 to combination by the excess of acid, and form a 
 triple salt ; likewise when to solution of perchloride 
 or muriate of mercury we add ammonia. 
 
 For two bodies to chemically combine their 
 components must have mutual momenta, and their 
 elements reciprocal potencies ; yet to any degree 
 these may be affected by concomitant circumstances, 
 as by multiples of one of the elements, by exhibiting 
 a third substance, or by absence of the motions of 
 heat, yet they all exist, though rendered sluggish. 
 In the atmosphere the oxygen and nitrogen can 
 chemically combine, yet their combinative potencies 
 are sluggish, although exceeding the ponderance of 
 their specific gravities ; and the circumstances may 
 be modified by the presence of hydrogen, carbonic 
 acid, and other substances. 
 
POTENCIES OF ELEMENTS. 57 
 
 The combinative potency of a compound may 
 foe communicative, yet, exhibited' to another, be 
 minus, solicited to recipience, and separated ; or be 
 plus, and solicit as the agent, separating the other, 
 and forming a fresh compound ; or be equal, and 
 both remain sluggish, with mere mixture, not 
 chemical results. Hence, a compound, exhibited to 
 an element, plus to each or one of the components, 
 and to that of the active component for the receptive 
 of the solicited compound, these separate, and two 
 other compounds result, of the most communicative 
 and least receptive elements, and of the solvent and 
 the most receptive, the separated component.* 
 
 * In a new treatise on " Natural Philosophy," by Mr. Exley, 
 are some mathematical demonstrations of the momenta and direc- 
 tions of Combinative Potencies, which I have verbally adapted to 
 my own views, and trust I shall not be censured by persons fond 
 of such analytical formulae. 
 
 To determine the Combinative Potencies, communicative 
 and receptive, of two components A B in a compound, mutually 
 soliciting each other (EXLEY'S Principles, Sect. II. Prop. 8) : 
 
 Let us assume that the two components are 
 precisely equal (Fig. 1) in bulk, bb', and mo- 
 mentum, mm', their primary distance a, any other 
 distance x, the space they traverse to combine s, 
 and /the multiple of their potency at the distance x. Then, 
 
 m 
 
 The combinative potency of A is to that of B as 5, and that 
 
 x 
 
 wi' 
 of B is to that of A as -% ; m its momentum divided by the 
 
 x 
 
 square of the multiple at the given distance ; and that of B is 
 similar; therefore, the whole potency when both have similar 
 
 m + m' 
 momentum, is ; and when either is communicative and 
 
 t ' ^ *& 
 
 the other receptive, it is 2 > an< ^ s = a <*> x. Hence 
 
58 -CHEMISTRY OF POTTEEY. 
 
 s and / 2 = 2 (m + m') ---, or / = 
 
 v* & X 
 
 Also, as m + m is to m, so is / to the combinative potency of 
 /2m 2 a =0 x\. 
 
 B = - ; and that of A 
 
 and consequently the momentum of A is to that of B as m' is to 
 m, as by other ways may be easily determined. Hence the space 
 traversed by A is to that traversed by B as m' is to w, allowing 
 for a little variation of the circumstances because of the peculiar 
 characters of the components. 
 
 While x exceeds b (Fig. 2.) the potency is 
 communicative ; but it is receptive when b ex- 
 ceeds x ; in Fig. 4, A is the latter and B the 
 former. With the components as 2, the poten- 
 cies are equal ; as 3, they vary, and A has more, or similar, or less 
 momentum, as m' exceeds, equals, or fails m, till as 5, when 
 excess of B commences, and continues, opposed, till A B again 
 become as at first. The momentum being active or positive when 
 communicative, and passive or negative when receptive. The 
 momentum of A is constantly to that of B as m' is to m ; and 
 consequently each always equals that of the other at the same 
 point in combinative potency and period of process. 
 
 When A B have equal bulks, placed as Fig. 1, 
 their combinative potencies remain quiescent, by 
 
 the momentum p ; because, only by excess of 
 
 momentum in either can they be separated or more 
 intimately combined. When their bulks are un- 
 equal, b exceeding b', their potencies remain quies- 
 cent when m = m', and A B are as Figs. 3, 4, 5. 
 Any additional momentum will move them either 
 way, as 4 ; and by the least excess in either they 
 will combine, as 3 ; but to separate them will re- 
 
 m + m' 2m 
 quire excess = jr 2 or -^ ; the converse will be as 5, where,. 
 
 in either, the least excess will separate them ; but to combine 
 
 2m 
 them, the excess must = -- 
 
POTENCIES OF ELEMENTS. 59 
 
 When m exceeds m', the potencies are quiescent only as 3 ; to 
 separate them, they must be as p , to combine them, as 
 
 p ; when m' exceeds m, they are quiescent only as 5, when 
 
 they combine, when they are as p , and separate when as 
 
 m' + m 
 
 b' 2 
 
 When both components are unsolicited, but have momenta 
 through a determined distance, a the greatest, a' the least 
 intervening distance, r r' their radii with orbital spaces. In 
 approximating (1) their momenta traversing from a to r = 
 
 (w + m'J - H. (2) The potency gained or lost from 
 to r' = J2(m * w'j * r J \\- (3) The potency lost from 
 
 r' to a' is -J2(m 4- m'\ - r~/J. The second case is one 
 of neutralisation when m = m' , or r = r', the potency 
 remaining constant when m = m', and the spaces being alike 
 when r = r'. 
 
 Also the potency increases when m' exceeds m, and de- 
 creases when m exceeds m' ; and the third case has the potency 
 communicative, receptive, or quiescent, as the momentum 
 lost in the second case fails, or exceeds, or equals, that gained 
 in the first case. 
 
 And as the potency is indifferent or sluggish at the distance 
 
 {a T T T' 
 
 (m + m') - + (ra' - m) - - 
 
 fV _ SJ ^ 
 
 (m + m') -rgT-ji = 0. 
 Therefore 
 
 r' r' a rra 
 
 ~ rr; 
 
 / and 
 
60 
 
 CHEMISTKY OF POTTERY. 
 
 (2.) To demonstrate that two substances with similar com- 
 binative potencies do not chemically combine, but only when 
 they are different. (Ibid., Sect. VII. Phen. 84, 85): 
 
 Suppose both A and 
 B combinative in Fig. 7, 
 or receptive in Fig. 8, 
 or mutually communi- 
 cative and receptive in 
 Fig. 9. Suppose the 
 short line a repre- 
 sents the momentum 
 and direction of A to- 
 
 p wards a solicited sub- 
 
 A W' ^^\?i> Fi g- * r~S ^Q P stance, also similarly 
 
 regarded by B, with 
 
 _ the momentum &>' and 
 
 ^ suppose the potencies 
 
 would be efficient between a and b, with the direction c, precisely 
 at some point m between the centres A B. The separate mo- 
 mentum of each, on the other side, is as a' b', and the combined 
 momenta in the direction e' from n also between A and B. 
 Therefore the combined momenta of A and B soliciting any other 
 substance nigh A, will be from points in A B between the centres 
 A and B ; and similarly will the combined momenta solicit a sub- 
 stance nigh B. The sum of the potencies is a momentum soli- 
 citing substances in the opposite positions precisely between the 
 centres, and at right angles to the line joining those centres, 
 as P Q, and for radii, in every way from that line as a centre. 
 This situation of the patients by the mutual momenta proves that 
 the compound momentum with the reaction affects both A B from 
 a plane through P Q, at right angles to A B, and between the 
 centres A and B. 
 
 When A and B are receptive (as Fig. 6.), atten- 
 tion to the direction of the darts, and repetition of 
 the previous reasoning, will prove that similarly 
 patients nigh AB are solicited towards points in 
 AB, between the centres A and B, as before they were/rom them ; 
 and the requisite momentum with the re-action directed both 
 ways, from a plane passing at right angles through P Q, affecting 
 the patients, and likewise causing separation. 
 
POTENCIES OF ELEMENTS. 61 
 
 When A is communicative, and B receptive, as Fig. 9, then, by 
 like reasoning and attention to the darts, the combined potencies 
 of A and B with expanded orbital spaces towards points outside 
 A and B, the reaction being from planes passing through P Q and 
 P' Q' at right angles to A B produced ; hence the compound forces 
 impel A B towards each other ; that is, they exhibit combination, 
 on the same principles, as when alike communicative they exhibit 
 separation. Were potency unappropriated, it must be without the 
 circles, where the action is greatest, because the section of one 
 is diminished by that of the other between them, which will 
 promote the combination. 
 
 Hence results the accuracy of chemical determinations. Did 
 the elements and their potencies, under the like conditions, ever 
 vary, no two essays to produce the same compound could be 
 relied on as efficient, whether by chemists of this or of any other 
 country. But such is the certainty of the science that whoever 
 weighs and combines 54 parts of nitric acid with 48 parts of 
 potash, will obtain a result of precisely 102 parts of nitrate of 
 potash (saltpetre) ; and every chemist knows that only this and no 
 other result can possibly ensue. But was a person to properly 
 weigh and combine 50 parts of dry carbonate of lime with 50 parts 
 of acetic acid, and say that the result was 100 parts of acetate of 
 lime although in numbers 50 and 50 make 100 every chemist 
 would know that the assertion is incorrect ; for 50 of carbonate 
 of lime and 50 of acetic acid form only 78 of acetate of lime, in 
 consequence of the carbonic acid evolving. Carbonate of lime is 
 a compound of calcium 20 + 8 oxygen = 28 lime, or oxide of 
 calcium, combined with 6 carbon + 16 oxygen = 22 carbonic 
 acid = 50 carbonate of lime ; and in combination of the sub- 
 stances the acetic acid solicits the lime, and the 22 of carbonic 
 acid is minus, leaving only 78, not 100, as the result of 50 and 50 
 chalk and acetic acid. 
 
 The importance of the subject being well-understood must be 
 my apology (if any be deemed needful by my subscribers) for so 
 fully stating these particulars, and in pursuing our investigations 
 of the almost infinite variety of compounds, from the energies of 
 these potencies, which we can prove, as far as our science goes, to 
 be those only energetic for Nature's purposes, and in which we 
 learn the wonderful and remarkable fact, that only very few 
 elements occur together ; we are gratified and interested with those 
 
62 CHEMISTEY OF POTTERY. 
 
 proceedings which result from our own manipulations ; although 
 not the most attentive and skilful of these, and of current pro- 
 cesses, suffice to accomplish like products with those which 
 astonish us as produced on the most magnificent scale in the 
 grand and vast laboratory of nature. 
 
[ 63 ] 
 
 MANIPULATIVE PEOCESSES FOE ANALYSIS. 
 
 IN the following details great care has been 
 exercised to fully and clearly particularise all the 
 consecutive steps of the General and the Special 
 Courses of Analysis adapted to supply the Manufac- 
 turer with accurate acquaintance with the behaviour 
 of Re-agents with the components of each Material. 
 This knowledge can be acquired only by experi- 
 menting ; and the person who has sedulously 
 regarded every change in the phenomena of a 
 process not seldom as sudden and unexpected as 
 the turning of a vane will have more correct and 
 adequate ideas thereof, than he possibly can have 
 who has several times heard them described, or read 
 their description. So faithful is the evidence of 
 which the eyes are made the medium of communica- 
 tion ; for although there may be amazement, there 
 cannot be deception. 
 
 By the manufacturer accustoming himself to 
 manipulation, he will acquire dexterity in using his 
 apparatus, and at pleasure pursue Analysis with 
 facility, economy, and accuracy. Commencing with 
 one experiment, he must practise all its manipu- 
 lations in succession, however multifarious, in the 
 best manner allowed by his opportunities and appa- 
 ratus, fully to understand the whole. He must 
 not indulge in the practice of some expert chemists, 
 to trust to appearances, and because facts are well- 
 known be careless and negligent to verify them. 
 He must compare his own observations with what is 
 
64 CHEMISTBY OF POTTERY. 
 
 current, and revise any glaring difference by repe- 
 tition of the processes. And the most attentive and 
 minute investigation of his subject may be well 
 compensated by the great satisfaction that would 
 arise from the discovery of some new combinations, 
 or unknown bodies. He must constantly register 
 every new research ; properly label and long keep 
 each portion of the results, which he must often 
 inspect, and notice any change in appearance ; 
 thereby the memory will be relieved, yet without 
 incertitude of their nature whenever again inspected. 
 By thus proceeding scarcely will it be possible for 
 imposing and deceptive half successes to produce 
 self-deception. 
 
 ANALYSIS is the general term for the Processes 
 of Chemistry, whether determinative or productive. 
 But it is divided into Analysis, or separation, and 
 Synthesis, or combination, as scarcely ever does the 
 former ensue unaccompanied by the latter. 
 
 Analysis -presents alone and distinct from each 
 other the component elements of a substance, and 
 determines their kind, nature, weight, combinative 
 potency, and relative quantities or definite propor- 
 tions ; also the phenomena when separating. And 
 Synthesis exhibits their distinctive characters when 
 becoming components of fresh compounds in char- 
 acters different from every other, although uniform 
 in the smallest portion. Neither of these, however, 
 develops the nature of the ultimate cause of these 
 effects and results, nor renders obvious the inter- 
 vention of the disjoined state which must necessarily 
 have occurred. To be completely successful in pro- 
 ducing simplicity of effect and certainty of results, 
 
PROCESSES FOR ANALYSIS. 65 
 
 we may apply the most particular knowledge of the 
 ascertained properties of bodies, and also employ 
 different pure substances, because of their use called 
 re-agents. 
 
 In every instance of the annexed details there 
 is absolute necessity for unremitted cleanliness, as 
 thereon often may depend most important results. 
 For this purpose it is proper to keep ready at hand 
 a towel, ewer of water, two bowls, a sponge, silk and 
 linen rags, tow, rods of whalebone, plain and capped 
 with sponge. Dirt of any kind is removed more 
 easily at first than when left to attach to an article 
 of apparatus ; therefore immediately must be washed 
 every glass vessel when emptied of its contents, 
 when there is least danger of breaking them. If 
 phials, shake well in them a few bits of raw potatoes ; 
 with the whalebone rod and sponge cleanse the 
 corners, and tubes, then immerse in pure water, and 
 place away for use. When oil or resinous fluids 
 have been used, rinse first with dilute sulphuric acid 
 or solution of potash, prior to using the potatoes. 
 Hereby will be prevented the unpleasantness of 
 having to cleanse a vessel at the moment when its 
 use might facilitate, perhaps complete, an important 
 process, and the consequent failure, and possible 
 sacrifice of time, labour and funds. Although at 
 commencement, when the mind is much engaged, 
 the trouble to cleanse and replace each utensil the 
 instant it is empty may be irksome and seem fasti- 
 dious, yet it most amply repays by freedom from 
 anxiety of its being ready for use, and by saving time 
 except what is just required for gently wiping off the 
 dust with the silk or linen rag. Every other kind of 
 
66 CHEMISTRY OF POTTERY. 
 
 utensil, as soon as its need ceases, must be cleaned 
 and replaced ; and time will be saved by " a place 
 for everything, and everything in its place." 
 
 To the re-agents the name Tests is also applied, 
 and Testing is the exhibition of a test to a com- 
 pound or solution. Each test so employed, whenever 
 active, causes a precipitate, white or coloured ; it 
 likewise in a peculiar manner solicits the components 
 of Salts, which are conjectured and determined from 
 comparing the effects of different tests on the same 
 solution. Their nature and utility are developed 
 in the analytic processes. Their names are the 
 following, in alphabetical succession : 
 
 Acid, Acetic, solicits to combination, metallic tin, 
 iron, zinc, copper, nickel, and the oxides of many 
 other metals, when a solution of the sulphate of any 
 is mixed with a solution of acetate of lead. With 
 magnesia it forms a viscid compound, but it has 
 very trifling combinative potency with alumine. 
 The most ready way of procuring it very strong is 
 to expose good vinegar to a freezing mixture ; to 
 abstract the crystals, cast them on a coarse rag in 
 a funnel for the acid to drain off; and when 
 pure, it is changeless by gallic acid, sulphate of 
 soda, hydrosulphurets, and sulphuretted hydrogen. 
 
 Acid, Boracic, a compound of boron and oxygen 
 (B 2 = 6), is of much utility as a flux for the blow- 
 pipe assay, as the highest temperature does not 
 volatilise it, neither do the compounds it forms 
 with minerals sink into the pores of the charcoal 
 support. Only the phosphoric acid remains in 
 combination efficiently opposing its soliciting the 
 base ; all others separate from bases on boracic acid 
 
PEOCESSES FOR ANALYSIS. 67 
 
 being present. Silicates are readily fusible with it, 
 and earthy compounds fuse into a limpid paste. 
 Davy first recommended its adoption to discover a 
 fixed alkali in minerals. It oxidates or separates 
 metallic iron, zinc, and copper, and it solicits to 
 combination most metallic oxides, also the alkalies 
 and the earths, the colour of the compound formed 
 with metallic oxides, etc., suggesting the probable 
 nature of the substance under examination. The 
 greater number of its combinations have had only 
 partial attention paid to their properties. (See the 
 Chapters on ACIDS and ALKALIES, also on GLAZES.) 
 Add, Muriatic (or hydrochloric, equal volumes 
 of chlorine and hydrogen), as formerly prepared 
 (from 1 part common salt and 10 parts dried clay, 
 well ground into a stiff paste, then put into a stone- 
 ware retort, and by a reverberatory furnace heat, 
 distilled over and collected), presented an excellent 
 example of combinative potency in the silica of the 
 clay soliciting to combination the alkali of the salt, 
 and forming a clear and durable glass. This might 
 have suggested an explanation of the action of the 
 salt in the glazing of the Crouch Ware. This acid 
 is of general use as a solvent, besides its value as 
 a re -agent. It causes a dense cloud whenever 
 ammonia is present. It precipitates silver and lead, 
 white, in aciduline solutions, but that of silver soon 
 becomes black in the solar ray ; is soluble in am- 
 monia but insoluble in water ; that of lead continues 
 white, is soluble in 22 parts water at 60 Fahrenheit, 
 and in dilute nitric acid. It also discovers man- 
 ganese in minerals, thus " the powder investigated, 
 
 F2 
 
68 CHEMISTRY OF POTTERY. 
 
 moisten with muriatic acid, gently heat, and chlorine 
 evolves when manganese is present ; in a platinum 
 spoon melt soda or borax, add the powder, keep it 
 melted in the inner flame of the lamp, the red colour 
 will gradually diminish, but will reappear in the 
 outer flame, or on adding nitre, when it is manga- 
 nese." (Ann. Phil, 1814.) When in company with 
 metallic tin, zinc, or potassium, by them is its 
 chlorine solicited to combination, a chloride of each 
 being the result, and liberating the hydrogen. 
 
 Acid, Nitric (equal volumes of hydrogen and 
 nitrogen, and three of oxygen), is much employed as 
 a solvent, because of the facility with which the 
 oxygen is separated, and the oxidated metals dis- 
 solved. In its concentrated state it is employed to 
 determine whether tin is pure or alloyed with 
 copper ; and much diluted, to distinguish steel by a 
 black spot, from iron by one greyish. It detects 
 nitrogen in animal substances, resin and starch in 
 vegetable substances, and uric acid in urine. 
 
 Acid, Oxalic, because of its greater combinative 
 potency with lime than with any of the other bases, 
 and separating it from all the other acids (unless 
 present in excess), is the most ready detector of the 
 presence of lime in liquids, forming a pulverulent 
 insoluble salt, only by fire decomposable. In like 
 manner it dissolves alumine, and when again by 
 fire the acid evolves, intumescence ensues. Its com- 
 binative potency is less with metallic iron, lead, tin, 
 zinc, and antimony than in forming triple salts with 
 most of the metallic oxides, also ammonia, soda, 
 barytes and magnesia. In solutions it separates 
 
PEOCESSES FOE ANALYSIS. 69 
 
 iron oxide from that of titanium, and in a boiling 
 solution of it the oxide of iron dissolves, and that of 
 cerium remains as a white powder. 
 
 The crystals of this acid, and the salts also em- 
 ployed, must be carefully purified by this process : 
 In distilled water dissolve the crystals, then filter 
 the liquid ; the water present keeps the particles 
 asunder ; by suitable gentle heat evaporate a portion 
 of the water till the particles appear to commence 
 solidifying, as by the pellicle or film seen on the 
 surface ; place the vessel on some folded paper to 
 repose twenty-four hours, remove the crystals and 
 carefully preserve from air between blotting-paper ; 
 repeat the evaporation and crystallisation until all 
 readily procurable are obtained. 
 
 The solution for testing should always be pre- 
 pared in a vessel with much larger capacity than the 
 mere quantity needed to preclude loss from effer- 
 vescence, or expansion of the mass by chemical 
 action ; and it should resist the action of the solution, 
 whether aciduline, alkaline, or aqueous. In this 
 vessel agitate the fine powder of the salt among the 
 liquid with an earthenware or glass rod, and when 
 all is mixed (as the solution is needed, saturated or 
 holding, at a known temperature, all it possibly can ; 
 or diluted with only a portion present), place a filter 
 in a funnel with the neck entering the phial, and 
 carefully decant the liquid, and closely stop when 
 filtered. The solution may require heat or cold, yet 
 without chemical action, the characters and proper- 
 ties of the components remaining after evaporation ; 
 but with chemical action it is a fresh substance, 
 
70 CHEMISTEY OF POTTERY. 
 
 wholly different from those of either component 
 separate, or of both merely mixed. 
 
 Acid, Sulphuric, is so combinative that a single 
 drop in a very large bowl of water will give a red 
 tinge to litmus paper. In its concentrated state, 
 sp. gr. 1*845, it has an oily consistence without 
 colour or odour. It determines the presence of other 
 acids, also of lead, mercury, barytes, strontia, and 
 also lime with certain bases. When accompanied by 
 several of the metals at a high temperature, they 
 solicit a portion of the oxygen to form oxides, which 
 combine with the remainder of the acid during the 
 evolving of the sulphurous acid gas. 
 
 Acid, Tartaric, solicits to combination alkaline, 
 earthy, and metallic bases, as tartrates, and is 
 employed to ascertain whether the alkali present in 
 a liquid is potash or soda, as the salt formed with 
 the former is very soluble, with the latter insoluble 
 in water. The solution is first concentrated, and 
 then excess of solution of tartaric acid is added ; 
 when the alkali present is potash, there is a crystal- 
 line precipitate, when it is soda, the mixture 
 continues clear, and seems unaffected. The crystals 
 should be dissolved only when to be instantly em- 
 ployed. 
 
 Ammonia, Liquid Caustic, is of general use to 
 neutralise aciduline solutions of bases, when potash 
 or soda would be improper. It is a compound of 
 3 volumes hydrogen and 1 volume nitrogen, with a 
 sp. gr. of 0*590, air being 1*000. The only metal 
 which it solicits to combination is zinc, which is 
 first oxidated and then dissolved, but it is equally 
 
PEOCESSES FOE ANALYSIS. 71 
 
 potent on the protoxide and peroxide of copper, 
 the oxide of silver, the third and fourth oxides 
 of antimony, very rapidly, but sluggishly on the 
 oxide of tellurium, protoxides of nickel, cobalt, iron, 
 and peroxides of tin, mercury, gold and platinum ; 
 the three last, with silver, being fulminative. With 
 the salts of the earths and metallic oxides it forms 
 triple salts ; thus when the compound is sulphates 
 of magnesia, lime and iron, with ammonia neu- 
 tralise any excess of acid, add succinate of ammonia, 
 and any peroxide of iron present will precipitate, 
 leaving the earths in solution. Or, the solution 
 evaporate dry, just incandesce 60 to 80 minutes, 
 which will decompose the sulphate of iron, leaving 
 the sulphate of lime insoluble, and the sulphate of 
 magnesia soluble in the water employed to digest the 
 calc. Of course, when only the first and the last are 
 present, whatever is insoluble will be oxide of iron. 
 When copper or nickel is present in a solution, 
 ammonia produces a clear sapphire blue colour. In 
 the liquid immerse a bar of zinc, or clean knife-blade, 
 and copper, but not nickel, will precipitate. With a 
 little ammonia, zinc precipitates white ; but this is 
 re-dissolved by plus of the alkali. When the solution 
 has the alkaline earths present, with alumine, all of 
 them precipitate on adding ammonia ; when only 
 lime and magnesia are present, it partially precipi- 
 tates the latter, but not the lime. When carbonic 
 acid is present, free, or united with magnesia, 
 ammonia solicits to combination part of the excess 
 of carbonic acid from the magnesia, and the fresh- 
 formed carbonate of ammonia precipitates carbonate 
 of lime, and also salts of alumine. Ammonia 
 
72 CHEMISTRY OF POTTERY. 
 
 separates iron from manganese thus : Dissolve the 
 pulverised mineral in muriatic acid, dilute much 
 with pure water, add ammonia till the litmus paper, 
 just red by vinegar, becomes blue, leave to repose 
 24 hours ; filter out the oxide of iron, the solution 
 evaporate dry, by incandescence expel the muriate 
 of ammonia, throw on a filter the oxide of man- 
 ganese, and wash well. 
 
 Ammonia, Benzoate of. In pure water dissolve 
 carbonate of ammonia, and add benzoic acid till the 
 solution is neutral or, to this solution, boiling, add 
 excess of gum benzoin next, filter, evaporate and 
 crystallise. This re-agent separates iron from all 
 earthy salts, also from nickel, cobalt, zinc, and many 
 other metals ; thus by ammonia neutralise the 
 aciduline solution, add much pure water, then drop 
 in the solution of the test while there is any precipi- 
 tate ; this filter out, wash well with cold water, dry 
 at 212, digest in ammonia 12 hours, filter out, and 
 then wash well the red oxide of iron ; the solution 
 evaporate, to recover the benzoate remaining. It 
 separates iron from manganese in solution ; thus 
 by any alkali neutralise the aciduline solution, then 
 gradually add this re-agent while there is any preci- 
 pitate ; all the iron falls, all the manganese remains 
 in solution. When earths also are present, again 
 acidulate the solution, and boil, to render inert any 
 benzoic acid present. 
 
 Ammonia, Carbonate of (like other carbonates 
 of the alkalies), precipitates most earthy and all 
 metallic salts in solutions, the respective colours 
 suggesting the bases. When copper is present the 
 solution has a blue colour. With phosphate of soda 
 
PROCESSES OF ANALYSIS. 73 
 
 this re-agent detects and separates magnesia from 
 the other earths present, and dissolves yttria, glucina, 
 and zirconia, whenever present in the solution. 
 
 Ammonia, Ferrocyanate of, is used solely with 
 solutions of salts. When they are of the metals, or 
 (neutral) of the alkalies, ferrocyanate of potash would 
 separate the former, yet not determine the previous 
 presence or absence of the latter ; but this re-agent 
 precludes incertitude by precipitating the former, 
 and the carbonate of ammonia the latter (the solu- 
 tion being raised to a temperature above 180 to 
 separate the magnesian salts). Filter, evaporate 
 dry, incandesce to expel the ammoniacal salts, and 
 leave free the yttria, glucina, and zirconia possibly 
 present. The calc boil in pure water, filter, and 
 evaporate for the alkaline salts. To determine 
 whether ammonia be (or not) present prior to 
 solution, add a little potash to the powder or salt, 
 .and ammonia will evolve if present. 
 
 Ammonia, Muriate of, will detect alkalies and 
 -alkaline earths, by which it is separated ; or, when 
 the salt is dry, by a moderate heat decomposed, and 
 the ammonia rendered sensitive. But, because in this 
 state, it is decomposed by many metals and metallic 
 oxides ; by other re-agents we determine the pre- 
 sence or absence of alkali or alkaline earth. When 
 .alumine is present in alkaline solutions, on exhibiting 
 this re-agent the alkali is solicited to combination 
 by the muriatic acid, the sp. gr. of the liquid is 
 -altered by the free ammonia, and the alumine preci- 
 pitates and must be filtered out, well washed, and 
 dried at 350, then be preserved for occasional use. 
 It detects platinum, by a precipitate, bright yellow, 
 
74 CHEMISTRY OF POTTEEY. 
 
 when pure ; orange, when irridium is present ; the 
 compound (of oxide of platinum, ammonia, and 
 muriatic acid), subjected to very high temperature, 
 is decomposed ; chlorine and muriate of ammonia 
 evolve, leaving spongy metallic platinum. The 
 hydrostatic test, or specific gravity, fails to verify 
 when gold has been adulterated by platinum, but 
 the aciduline solution treat with green sulphate of 
 iron in solution to precipitate the gold, and by this 
 re-agent find the platinum. 
 
 Ammonia, Oxalate of, detects the most minute 
 portion of lime present, even to the twenty-four 
 thousandth part in water, when the solution has its 
 mineral acid accurately neutralised by an alkali 
 (proved by restoring to blue the litmus paper made 
 red by vinegar) or is freed from barytes or strontia 
 by sulphuric acid. This re-agent also precipitates 
 magnesia during twenty-four hours' repose. 
 
 Ammonia, Succinate of (also, of Soda), care- 
 fully dropped into a solution detects (not protoxide 
 but) peroxide of iron, separates the oxides of iron 
 and manganese, and in slightly aciduline solutions 
 precipitates alumine, glucina, and zirconia. 
 
 Ammoniacal Sulphate of Copper. With blue 
 vitriol (or sulphate of copper) saturate liquid am- 
 monia, and employ the compound to discover arsenic 
 in any solution or liquid. The yellowish green pre- 
 cipitate is soluble in ammonia and most acids, but 
 not in water, and must be dried and reduced with 
 the black flux to determine the presence of metallic 
 arsenic. The charcoal of the black flux (nitre 1 + 
 supertartrate of potash 2, detonated) solicits to 
 combination the oxygen of the white oxide, and as. 
 
PKOCESSES FOE ANALYSIS. 75 
 
 carbonic acid gas evolves, while the further separa- 
 tion is promoted by the alkali and excited com- 
 bustion, leaving the arsenic in its metallic state. 
 The process, carefully conducted, alleviates the 
 weariness of persevering attention by the suitable 
 and pleasant manner in which the mind acquires 
 correct information how substances either combine 
 or separate, and reciprocally produce results in 
 accordance with certain principles. 
 
 Arsenious Acid (or white arsenic) will detect 
 lime in solution by a white precipitate, which is 
 soluble in excess of the re-agent. And when present 
 in only one hundred thousandth part of the solution 
 will form with sulphuretted hydrogen, or hydro- 
 sulphuretted solutions, a beautiful golden yellow 
 precipitate of sulphuret of arsenic. This, filter out, 
 wash, dry, and place in a test-tube with a bit of 
 caustic potash ; in the flame of the blow-pipe lamp 
 decomposition ensues, the sulphuret of potash is at 
 the bottom, and on the sides sublimes the metallic 
 arsenic, with steel -bright lustre. This acid solicits 
 to combination all the pure alkalies and alkaline 
 earths ; the arsenites of potash, soda, and ammonia 
 are soluble and not crystallisable, but scarcely soluble 
 are those of lime, barytes, strontia, and magnesia. 
 The golden yellow precipitate by the hydrosulphurets 
 of alkalies results readily when the arsenious solution 
 is previously treated with a drop or two of nitric or 
 muriatic acid. The peculiar yellow precipitate by 
 nitrate of silver would be re-dissolved by nitric acid 
 if this be left unsolicited by a few drops of ammonia, 
 yet only a few must be used, else the like result will 
 ensue. A beautiful and very distinctive grass-green 
 
76 CHEMISTRY OF POTTERY. 
 
 precipitate is formed with diluted ammoniacal 
 sulphate of copper, which, well washed, is rendered 
 brownish-red by sulphuretted hydrogen water, blood- 
 red by ferrocyanate of potash, and yellow arsenite by 
 nitrate of silver. 
 
 Barytes-water. By very high temperature de- 
 compose the nitrate of barytes, or with like tem- 
 perature decompose a mixture of sulphate of barytes 
 with carbonate of potash, and incandesce the result- 
 ing carbonate. The caustic barytes thus obtained 
 dissolve in pure water to saturation. This readily 
 detects either carbonic or sulphuric acid, however 
 present, the precipitate of the former being soluble, 
 that of the latter insoluble, in dilute nitric or 
 muriatic acid. 
 
 Barytes, Acetate of, is very useful to determine 
 which, and how much, alkali or alkaline sulphate 
 is present in a solution. 
 
 Barytes, Muriate of, detects sulphuric acid, free 
 or combined, the precipitate being soluble in concen- 
 trated acids, but scarcely in pure water, hence can 
 be fully obtained. When alkaline carbonates are 
 present, a few drops of muriatic acid is exhibited to 
 prevent this re-agent being inert. And when the 
 muriatic acid of this test might embarrass the deter- 
 minations of the analysis, we use Nitrate of Barytes. 
 
 Cobalt, Nitrate of. In nitric acid dissolve co- 
 balt, metal, or oxide, then evaporate to the needed 
 strength. With a concentrated solution just moisten 
 the mineral fine powder, and on platinum foil submit 
 it to the white flame of the blow-pipe, and when 
 alumine is more plentiful than iron or other colorific 
 oxide, soon is seen a blue assay, more or less brilliant 
 
PEOCESSES FOB ANALYSIS. 77 
 
 and intense, as the alumine is pure and in excess. 
 Gahn says this is infallible. 
 
 Copper, Sulphate of, by a bright yellowish- 
 green precipitate also detects arsenic in solutions 
 treated with a small portion of alkaline carbonate ; 
 also sulphuretted hydrogen by a dark brown 
 precipitate of sulphuret of copper. 
 
 Gold, Muriate of, detects the presence of tin 
 at its minimum of oxidation. 
 
 Iron, polished, as wire, bar, or plate, solicits 
 to combination, or separates from aciduline solutions, 
 copper, antimony, and tellurium in the metallic 
 state. 
 
 Iron, Protosulphate of, solicits the oxygen 
 from gold and palladium in aciduline solutions, 
 leaving the metals to precipitate. It also detects 
 oxygen in any water where it is present by a 
 brownish precipitate, and gallic acid by one which 
 becomes black when exposed to the atmosphere. 
 
 Lead, Acetate of, a most useful detector of 
 sulphuretted hydrogen, or hydrosulphurets, by a 
 black precipitate. It also detects muriatic and 
 sulphuric acids by a white precipitate, the former 
 soluble, the latter not, in dilute nitric and acetic 
 acids, and by a white precipitate likewise phosphoric 
 acid, proved by the blow-pipe. 
 
 Lime, Muriate of, is occasionally employed to 
 detect alkaline carbonates, by which it is separated, 
 and left as carbonate of lime. This is also used, 
 when its water is dissipated, as chloride of calcium, 
 to abstract water where its presence would be 
 deleterious. 
 
 Mercury, (also Silver-leaf), by losing the previous 
 
78 CHEMISTKY OF POTTERY. 
 
 brilliance detects the presence of the most minute 
 portions of sulphuretted hydrogen gas or hydro- 
 sulphurets of the alkalies (in mineral waters 
 especially). 
 
 Mercury Protonitrate of, detects the one thirty 
 thousandth part of free ammonia in water by a 
 blackish-yellow tint, and when in plenty by dark 
 grey or black precipitate ; sulphuric acid by a white 
 crystalline precipitate, which repeated affusion with 
 boiling water renders yellow ; also muriatic acid 
 and phosphoric acid (when neither alkali nor alkaline 
 earth is present) by a white precipitate ; the former 
 soluble, the latter not, in nitric acid. It gives, with 
 muriate of gold, a dense bluish-black precipitate, and 
 orange coloured, with muriate of platinum. 
 
 Mercury, Cyanuret of, detects palladium by a 
 yellowish-white precipitate, fulminative by raised 
 temperature. 
 
 Mercury, Perchloride of, (always kept in a 
 covered phial) detects alkalies, alkaline earths, and 
 ammoniacal salts the caustic alkalies by a yellow, 
 the carbonated alkalies by an orange- coloured 
 precipitate. 
 
 Platinum, Muriate of, by a yellow precipitate 
 (bichloride of platinum and chloride of potassium) 
 distinguishes salts of potash from those of soda, 
 which it does not affect, in solutions concentrated 
 but without excess of acid. It also detects the 
 presence of lime. 
 
 Potash, Ferrocyanate (triple Prussiate) of, by the 
 colours of the precipitates detects the presence of 
 certain metallic oxides. With the protoxide of iron 
 the precipitate is white, but soon becomes blue in the 
 
PROCESSES FOB ANALYSIS. 79 
 
 air, and with peroxide it is Prussian blue. The 
 earths are very sluggish to its action. 
 
 Silver, Acetate of, is used to determine nitrates 
 and muriates whenever employing nitrate of silver 
 might embarrass the analysis by additional nitric 
 acid. Also more readily to discriminate the alkali of 
 a muriate by evaporating dry the liquid treated with 
 acetate of silver, then re-dissolving the dry mass in 
 alcohol, and again evaporating dry ; a deliquescent 
 salt will indicate potash, and an efflorescent salt will 
 indicate soda. The test must be kept in a covered 
 phial. 
 
 Silver, Nitrate of. To pure water 50 parts, and 
 concentrated nitric acid 25 parts, add 25 parts of 
 grain silver, or silver-leaf, and keep in a sand-heat 
 till dissolved ; then by more heat evaporate to the 
 needed concentration for use, and preserve in a 
 covered phial. This re-agent, by a white curdy pre- 
 cipitate, rendered black by the solar rays, soluble in 
 ammonia but not in water or nitric acid, readily 
 detects chlorine and muriatic acid, whether free or 
 combined ; and a grain of common salt in 42,250 
 grains (more than 5 pounds) of pure water is 
 recovered in white clouds, yet only is the muriatic 
 acid the y^W P art f tne water. The presence of 
 sulphuretted hydrogen and hydrosulphurets is in- 
 dicated by a black precipitate of sulphuret of silver ; 
 chromic acid by a red carmine precipitate of chromate ; 
 arsenic by a yellow arsenite nitrate or acetate of 
 barytes being previously introduced to remove 
 sulphuric and sulphurous acids, and nitric acid 
 to saturate any carbonated alkali. The precipitated 
 carbonate of silver, by using alkaline carbonates, is 
 
80 CHEMISTEY OF POTTEEY. 
 
 soluble with effervescence in dilute nitric acid, but 
 not that by using muriatic acid. 
 
 Silver, Sulphate of. Solution of nitrate of silver 
 treat with plus of sulphuric acid, filter out the pre- 
 cipitate, wash till the litmus-paper is not altered ; 
 in distilled water boil the precipitate, cool, filter, 
 concentrate to the required strength, and preserve in 
 a covered and well-stoppered phial. It best detects 
 muriatic acid where nitrate of silver might suffer 
 from the presence of sulphurous or sulphuric acid. 
 
 Soda, Borate of (or Borax), in its native state, 
 called Tincal, is found in the East Indies and in 
 South America, and is purified by long boiling in 
 plenty of water, which after being filtered is left to 
 crystallise. Boiling-water dissolves one-sixth, cold 
 one-eighteenth, of its weight. In this state it is 
 called common borax. When heated it intumesces, 
 loses its water of crystallisation, becomes white, 
 porous, opaque, or calcined borax ; and by a stronger 
 heat it fuses into a greenish-yellow vitreous and 
 transparent substance, or glass of borax, soluble in 
 water and efflorescent in air. Some have supposed 
 the alkali more than triple the quantity needed to 
 saturate the boracic acid ; others that it is Sodium 
 1, + B. A. 5, + Ox. 3. In the analysis of minerals 
 glass of borax readily causes fusion of those which 
 are sluggish with alkalies ; and borax in its several 
 states is an excellent flux for earthy substances and 
 metallic oxides. 
 
 Soda, Phosphate of, is used with bicarbonate of 
 ammonia to separate magnesia in solutions ; also, 
 when free from the water of crystallisation, as a flux 
 in the blow-pipe assays, being more easily managed 
 
PEOCESSES FOE ANALYSIS. 81 
 
 than the microcosmic salt (phosphate of soda and 
 ammonia,) and promoting the fusion of earthy 
 substances and metallic oxides. 
 
 Soda, Sulphate of (or of Potash), is the best 
 re-agent to detect the presence of lead. The white 
 precipitate is soluble in warm diluted nitric acid, but 
 not in water or ammonia, and is rendered black 
 by sulphuretted hydrogen- water, thus distinguishing 
 lead from barytes. 
 
 Tin, Protomuriate of, detects the presence of 
 gold by a fine purple precipitate (the Purple of 
 Cassius) ; of platinum by one orange-coloured ; of 
 perchloride of mercury (corrosive sublimate) by a 
 dark brown ; of palladium by one similar, but by 
 excess of the test the solution has a fine emerald- 
 green transparency. 
 
 Zinc may be employed to separate, in solutions 
 which have scarcely any excess of free acid present, 
 metallic copper, lead, tin, silver, and tellurium ; and 
 also lead, tin, copper, and tungsten, from their 
 alkaline solutions. But care is needed to prevent a 
 portion of the zinc precipitating as an oxide, or an 
 alloy. 
 
 Zinc, Hydriodate of. In distilled water digest 
 equal weights of scales of iodine and zinc filings 
 twenty-four hours ; filter and keep well-covered. 
 This fresh re-agent gives to the salts of most metals 
 by it precipitated from neutral solutions distinctive 
 colours, equally with sulphuretted hydrogen, hydro- 
 sulphurets, and ferrocyanate of potash. The preci- 
 pitate of nitrate of silver is yellowish-white ; muriate 
 of platinum deep brown-red ; nitrate of mercury, 
 
 dull orange ; muriate of mercury, dull brown ; 
 
 G 
 
82 CHEMISTEY OF POTTEEY. 
 
 nitrate of lead, bright lemon ; muriate of bismuth, 
 grey ; nitrate of bismuth, chocolate ; muriate of anti- 
 mony, black ; nitrate of antimony, first orange ; well- 
 mixed, black ; muriate of nickel, black ; nitrate of 
 nickel, light yellowish-brown ; muriate of copper, 
 greenish-cream colour ; acetate of copper, dirty light 
 olive-green ; muriate of tellurium, rhubarb colour. 
 
 The following has been announced as a pre- 
 cipitant of all metals : In pure water dissolve 
 sulphuret of lime ; filter free from atmospheric air, 
 concentrate the solution, and keep well-secured from 
 the air. The solution may be evaporated and 
 crystallised till all is obtained, and the crystals must 
 be kept secured from the action of the atmosphere. 
 
 The solutions, or supernatant liquids, and some 
 of the results may seem of trifling value ; but it 
 may always be worth while to carefully decant into 
 small covered jars all sorts, and place each aside ; 
 wipe clean the outside, label the contents, numbered 
 to agree with the registered details, and frequently 
 inspect during all the time they are preserved, and 
 carefully register whatever changes appear. Many 
 grand discoveries of the science were suggested by 
 phenomena of long-retained results : which would 
 not have rewarded the perseverance of those to 
 whom we owe them had the label been neglected, or 
 the different phenomena disregarded, or the liquids 
 hastily cast away as valueless. 
 
PULVEBISATTON. 
 
 WHEN a substance is submitted for analysis, it 
 is proper to notice its induration, or pulverulence, 
 specific gravity, hardness, texture, scintillation with 
 steel, result under the nail, crystal or hard stone, 
 permeate by light, homogeneous, or heterogeneous 
 character. Next prove, First, its accession or dimi- 
 nution of weight, also its being soluble or not in 
 water, by boiling or digesting; Second, whether 
 en masse, or in powder, it yields to acids, effervescing, 
 or to solution of caustic potash ; Third, whether it 
 detonates or not with nitre ; Fourth, what results 
 when distilled with sulphuric acid or potash ; 
 Fifth, what phenomena appear under the blow-pipe, 
 alone, or with soda, borax, or mic. salt, on charcoal 
 or platinum foil ; also whether it decrepitates on 
 gradual rise of temperature. 
 
 When a stone that scintillates with steel fuses 
 alone, we know that there are present lime, or 
 calcareous earth, and silica ; with another, either 
 alumine or magnesia (by a few supposed a modi- 
 fication of lime), and probably a metallic oxide, 
 iron, manganese, nickel, copper, and chrome. 
 
 When the mineral is hard, and requires to be 
 pulverised, it is proper to weigh a small portion, 
 place in a covered platinum crucible, raise to a white 
 heat or bright incandescence, and weigh to determine 
 its loss or gain by the heating ; then throw it into 
 cold water to render it brittle and easily pulverised ; 
 
 again weigh, and register any difference should 
 
 G 2 
 
84 CHEMISTRY OF POTTERY. 
 
 volatile elements evolve. Wrap in paper, and with a 
 hammer and a smart, hard stroke, crush or break it. 
 
 When not needed to be very comminute, in a 
 Wedgwood's mortar (No. 2, 3 inches wide, and Ij 
 deep), by a dexterous motion of the pestle round 
 the sides, triturate or rub the mineral till its primary 
 colour is entirely changed, from being dry appears 
 moist, retains any impression of the spatula, and is 
 not gritty rubbed between the thumb and finger 
 (this however causes loss), and can be readily taken 
 out by a spatula of glazed card. For small quan- 
 tities of salts, this mortar and process will be found 
 most useful. When not restricted to the exact 
 quantity, the soluble fine powders may be passed 
 through a lawn sieve, and the insoluble washed 
 over, as subsequently directed. 
 
 When the powder must be very fine, on a 
 porphyry slab with a muller, or in a flint or agate 
 mortar with a pestle, rub or levigate in water, till 
 proper for the purpose, keeping the mass in the 
 centre of the slab by means of a clean cut card, bone 
 folder, or palette knife. Powders of different com- 
 minution are obtained thus : mix the substance in 
 water, let it repose two minutes, and decant into a 
 bowl ; add more water to the first mass, agitate 
 well, wait a minute, and decant into another bowl ; 
 repeat the process twice or thrice more ; the finer the 
 powder, the longer will it remain suspended in the 
 water ; and to obtain this for qualitative analysis, 
 evaporate the water slowly. After the powder is 
 dried and weighed, any increase of weight will be 
 from abrasion of the mortar, and must be taken 
 into the account. 
 
[85] 
 
 THE BLOW-PIPE ANALYSIS. 
 
 THE blow-pipe is now become indispensable to 
 analytic chemistry, and its use cannot be too soon 
 carefully acquired and steadily practised. Its advan- 
 tages are numerous and in- 
 calculable in the detection 
 of fixed bases, and in the 
 formation of useful glass 
 articles of apparatus. The 
 figure in the margin shows 
 how it must be used, and 
 also the method of holding 
 it properly. 
 
 The word Base strictly signifies that elementary 
 component of a compound, whether alkali, earth, or 
 metal, which solicits, or is solicited, to combination 
 with the other elementary component, and from 
 whose combinative potency there are definite results, 
 in accordance with the nature of the components 
 and the condition of their combination. But it has 
 been extended, not philosophically, to indicate those 
 substances which when in atmospheric air are 
 united to oxygen, etc., form compounds, as though 
 it supplied the distinctive properties, which, in fact, 
 result from the combination, and the qualities 
 which depend as much on the state of combination 
 as on the nature of the component. 
 
 The blow-pipe employed for chemical and 
 mineralogical purposes, whether formed of brass, 
 
86 CHEMISTET OF POTTERY. 
 
 tin-plate, silver, platinum, or glass, is varied in length 
 according to the sight of the operator, as it must 
 allow the substance (usually called the ASSAY), when 
 subjected to the flame, to be only at that distance 
 most distinctly and clearly perceptible by the eye, 
 and which is from six to eight inches. The mouth- 
 piece is flattened or oval, and frequently formed 
 of ivory ; at some part of the tube is a bowl, or 
 enlargement, wherein the vapour of the breath 
 condenses and remains in moisture ; and movable 
 nozzles for a stronger or finer blast, with each aper- 
 ture truly round and smooth, and in different sizes. 
 
 There are several compound blow-pipes con- 
 structed to be supplied with air from bladders, or 
 reservoirs, filled by the mouth at intervals ; others 
 are supplied by a pair of double-bellows fixed beneath 
 a table, or by equivalent contrivances ; and others 
 are adapted to consume mixed gases from gas- 
 holders, bladders, or reservoirs, or only mixed before 
 effluxion at the fine jet, to preclude explosion. 
 
 Each of the COMPOUND BLOW-PIPES called 
 Gurney's, Brooke's, Tilley's, Clarke's and Toft's 
 (cheapest) has its peculiar advantages in using, but 
 is expensive to a person of limited income. That 
 which I employ costs very little, because the more 
 expensive parts, taps, are useful in other processes. 
 I have a piece which by a screw is fixed to a table. 
 The piece is perforated, and tapped for screws on its 
 upper and under surfaces ; likewise on the outer and 
 two sides. Into the top I screw a cock-spur gas-tap, 
 to which I have three jets of different-sized perfora- 
 tions, also an extra piece filled with fine loose iron 
 filings, for insertion betwixt the pipe and jet when 
 
BLOW-PIPE ANALYSIS. 87 
 
 consuming gas. Into the lowest aperture I screw my 
 tap, connected with a reservoir (bladder, or elastic 
 gum cloth), and likewise screw taps into the two 
 sides. The outer hole admits to have screwed into 
 it an angular piece with a valve at the end inserted, 
 and into the other end of this screws a blow-pipe, by 
 which I can fill my reservoir at convenience. Thus 
 either one or more bladders can be attached, with 
 distinct or mixed gases, at pleasure ; or only common 
 air can be used, as the occasion may require. At 
 present, I have not had the disaster of an explosion ; 
 neither do I expect it, as each gas mixes with the 
 other only just when expelled from the pipe. 
 
 But instead of bladders we can employ Indian 
 rubber bottles, prepared thus : Very black, large, 
 even bottles, first are immersed fifteen to twenty 
 minutes in boiling water, then cooled ; on the flanged 
 end of the tap the neck of the bottle is carefully tied 
 by a waxed string ; the air (or the gas) is condensed 
 into the bottle. At first a blister appears, and gradu- 
 ally enlarges till the bottle has all like thickness * 
 then the condensation ceases, the tap is stopped, and 
 can be affixed to the table-piece. Two of these 
 bottles of atmospheric air will serve an hour, and 
 of gas much longer. And by using the double 
 (or T) connector of gas fittings, the supply may be 
 continued ad libitum without disturbing the process. 
 And not the least surprising part of the affair is the 
 fact that when oxygen and hydrogen are condensed 
 together in the exact proportions which when de- 
 tonated form water, and the mixture is through a 
 pipe and fine jet directed upon the flame of a lamp 
 (forming the oxy-hydrogen blow-pipe), we readily 
 
88 CHEMISTRY OF POTTERY. 
 
 obtain not previously imagined degrees of heat, 
 whose potency has subdued the most refractory 
 substances. 
 
 When the simple blow-pipe is used, a candle of 
 tallow, or of wax, with a thicker wick than common 
 is employed to supply the flame. Convenience is 
 the first object, and this is so ; but the radiant heat 
 of the assay so soon melts the wax or tallow, and 
 causes the wick to consume so quickly, that even the 
 trouble of snuffing is a drawback in important pro- 
 cesses. I find a lamp made with a beak into which 
 the wick is held by a wire collar, and over which a 
 hood can be readily placed, very useful ; the wick is of 
 soft cotton roving, clean, dry, and scarcely twisted, 
 and olive oil is best, but purified rape oil and hog's 
 lard will be found the only proper substitutes. The 
 oils should be kept corked when not in the lamp, 
 and the wick must be destroyed. This lamp will 
 answer all purposes of the operator, with the com- 
 pound blow-pipe, when gas is not used ; and the 
 bright clear flame, devoid of smoke, can be managed 
 most advantageously. 
 
 With the blow-pipe and lamp, or candle, the 
 operator may effect an assay with heat more ardent 
 than that of a furnace. In a few minutes he can 
 ascertain the general nature and properties of even 
 the most valuable mineral, or chemical compound, 
 by the minutest portion thereof, in reference to 
 fire ; and, free from the uncertain conjecture of what 
 occurs in the centre of a furnace, wherein such an 
 experiment might be made on a large scale, he can 
 witness the commencement and the conclusion of 
 all the appearances and their proximate causes, the 
 
BLOW-PIPE ANALYSIS. 89 
 
 chemical or the mechanical mixture or conglomera- 
 tion of the components, and ascertain and determine 
 results, which else would require large furnaces, 
 great quantities of substances, cumbrous apparatus, 
 and many hours of attentive investigation. The 
 only drawback on its excellence is its not deter- 
 mining the proportions of the components. 
 
 With the simple blow-pipe most readily, and 
 with least fatigue to blow, so that the stream of air 
 may flow uninterruptedly against the flame during 
 the continuance of the experiment, even when that 
 is occasionally several minutes, the operator must 
 attend to these particulars : First acquire the prac- 
 tice of breathing through the nose while the tongue 
 touches the roof of the mouth, and the lips are closed ; 
 this will probably be affected in from ten to forty 
 minutes. The muscles of the mouth will soon con- 
 form to this fresh kind of exertion. Next, breathe 
 through the nostrils, and yet keep the cheeks dis- 
 tended with air all the time ; afterwards inspire 
 several supplies of air while the cheeks are filled ; 
 and at length, with the cheeks full, easily compress 
 them, and let the air flow through the pipe, even 
 while inhaling a supply by the nostrils, keeping the 
 tongue to the roof, unless when instantly supplying 
 air from the lungs. The lips will be subject to 
 lassitude on the first trials, but determined perse- 
 verance is requisite, and with this the operator will 
 successfully blow for any length of time with only 
 little inconvenience. 
 
 The next important remark is, that wherever 
 the operator wishes to most readily effect his object, 
 he must be secure from any current or draught of 
 
90 CHEMISTEY OF POTTEKY. 
 
 air, that his exertions may not be unnecessarily 
 lengthened. And also, that there is no subject he 
 may possess but will be worse for violent blow- 
 ing, and rarely is any refractory to continued 
 moderate exertions. 
 
 Let the wick of the lamp, or candle, be a little 
 bent, or the candle oblique. Direct the stream of air 
 from the pipe along the wick, but without striking 
 the flame, and notice that when the aperture is too 
 large an irregular cone will be formed, and when it 
 is not round and smooth, the cone will be ragged or 
 rough. But when the orifice is proper, the cone will 
 have an inner portion, light blue, pointed, and an 
 inch long this point has the most intense power 
 and an outer portion, vague, brown, varied in length,, 
 and with diminished power. By the former, carried 
 brilliantly and equally on all parts of the assay, 
 which never needs to be larger than a grain of 
 mustard seed, the operator can reduce or de-oxidate ; 
 and by the outer, all the combustible particles will 
 quickly be saturated with oxygen, and the substance 
 be oxidated, not acidified. A small bit of grain tin 
 is useful to ascertain the reducing flame, and the 
 degree of exertion needful to keep it reddish-white 
 on charcoal. 
 
 DR. FARRADY says, the aperture of a blow-pipe 
 should be the fortieth or fiftieth of an inch diameter. 
 The jet end may be platinum. The mouth and cheeks 
 should act independently of respiration by the nos- 
 trils, so as to maintain a constant current. Success 
 depends on knack and practice. For ordinary pur- 
 poses a tallow or wax candle, or lamp wick, are 
 sufficient, but for great heats broad flat wicks, are 
 
BLOW-PIPE ANALYSIS. 91 
 
 used. The blast should be directed a little above 
 the wick, and from a candle inclined a little upwards 
 to prevent guttering. The greatest of the blow-pipe 
 flame is at the extremity of the blue cone, where the 
 combustion is complete, that is, where the hydrogen 
 and carbon of the wick are in equilibrium with 
 the oxygen, and fix its maximum quantity. There 
 should be neither flame nor smoke at the extremity. 
 When oxygen gas, from a caoutchouc bag or vessel, 
 is urged through the pipe, the heat is the greatest 
 known to art. Sometimes condensed oxygen is 
 forced into vessels, and a strain produced by opening 
 a cock. Hydrogen, too, has been used with oxygen 
 instead of lamps, and the effect is more powerful, 
 but attended with danger of explosion. The sub- 
 stance should be fixed on sound charcoal, or in a 
 platina spoon, or on white clay. With oxygen and 
 hydrogen platinum runs in drops, and palladium 
 melts like lead ; every substance yields. 
 
 The student will find this indispensable, to 
 ascertain their nature and habitudes ; and as they are 
 often connected, the following notices of the many 
 and varying appearances of the assay, alone or com- 
 bined with fluxes, on supports of charcoal, metal, or 
 glass, under the effect of the outer or inner flame, 
 will direct his conclusions in reference to the results. 
 When expense is disregarded, a series of ticketed 
 mineralogical specimens are useful. He must also 
 understand that the practical difference between the 
 assay and the analysis of a mineral is the assay 
 determines the presence of a particular base, and the 
 analysis demonstrates, from a definite weight, the 
 
92 CHEMISTRY OF POTTEEY. 
 
 nature and precise quantities of all the valuable or 
 worthless components. 
 
 The assay cannot be too thin, as only the point 
 of the flame acts on it ; and olive-oil or water is used 
 to form powders into a paste. The assay is tried on 
 supports which do not chemically combine with it. 
 Small pieces of Alder charcoal, four to six inches 
 long, are useful for oxides and metallic minerals, as 
 a perforation upwards will retain the whole assay, 
 and also the oxygen which facilitates the process. 
 Small slips of platinum foil enfold an assay, and 
 unwrap after the process. Hooked platinum wires, 
 two to three inches long, bear the flux to fuse into 
 a globule, in which the assay is fixed by moisture, 
 and all changes are very obvious. A small glass 
 matrass, and an open tube of glass, three inches long, 
 and one-eighth diameter, will receive an assay when 
 volatile components not permanently gaseous are to 
 be sublimed. A useful implement is a pair of 
 forceps, with platinum points like ear-picks. 
 
 Roasting the assay in the glass tube, by heat, 
 expels all the sulphur and arsenic ; known when 
 Brazil wood test-paper does not bleach, neither is 
 there an odour like that of garlic. 
 
 Decrepitation is prevented by first heating the 
 charcoal and introducing the assay gradually from 
 the upper end, bringing the flame on it till red-hot. 
 Or, place the assay either in a groove between two 
 slips of charcoal, or in melted borax, platinum tube 
 or foil, matrass or tube, on which direct flame. 
 
 Reduction. Metallic oxides, fused into a glass 
 bead, the metallic particles form a globule ; soda is 
 
BLOW-PIPE ANALYSIS. 93 
 
 added ; the heat is continued, and in the inner flame 
 all is absorbed by the charcoal ; next cool by a drop 
 of water. The assay is abstracted, ground fine in 
 agate mortar, and by the dropping bottle carefully 
 are washed away the soda and the charcoal. 
 
 The following appearances are constant : The 
 assay, alone, either does or does not in the matrass 
 evolve water (to be tested) change colour decre- 
 pitate give off volatile matter, odourant of garlic, 
 (by arsenic), or brimstone (by sulphur), or horse-radish 
 (by selenium), or by mercury. And on charcoal, in 
 outer, then in inner flame, evolve volatile matter (as 
 above), decrepitate when roasted, be magnetic, melt 
 intumesce, or bubble effervesce, or sputter 
 volatilise colour the flame burn change colour 
 be absorbed by the support fuse, and supply a 
 bead, ash, globule, or enamel. And on charcoal, 
 with a flux, fuse intumesce effervesce change 
 transparence colour the flux detonate be ab- 
 sorbed colour the flame fuse, and yield a result 
 as above. 
 
 A Flux added to the assay assists its fusion, 
 and in the dry way, or with fire, has similar use to 
 an acid, or an alkali, in the humid way. It acts 
 chemically in separating the acid of a metallic oxide 
 from the base, in also dissipating the oxygen and 
 leaving the base pure. But mechanically when by 
 it the compound agglomerates into a button. 
 
 The three Fluxes for mineralogical chemistry 
 are thus prepared : The BORAX is common borax 
 boiled a long time, evaporated, and in small crystals 
 preserved, to be applied to bits of the assay (seldom 
 to powder) by the moistened point of the knife. 
 
94 CHEMISTRY OF POTTEEY. 
 
 SODA (indispensable to discover minute portions of 
 reducible metals) is common subcarbonate in solu- 
 tion, and excess of nitric acid ; by nitrate of barytes, 
 separating sulphuric acid, and the muriatic, by 
 nitrate of silver. The fluid evaporate, fuse, decom- 
 pose with charcoal ; wash the residue, crystallise 
 the solution, and preserve the crystals. Or, dissolve 
 subcarbonate in water, filter, slowly evaporate, skim 
 off the small crystals, cool, crystallise, and preserve 
 the crystals, to be used in fine powder, but in 
 different proportions with silicious minerals, as a 
 part may be absorbed by the charcoal support. 
 MICROCOSMIC (or Mic.) SALT (Salt of phosphorus, 
 or phosphate of soda and ammonia). Crystallise 
 a solution of phosphates of soda and (excess) of 
 ammonia (or 16 parts sal ammoniac and 100 
 phosphate of soda), heat, filter, and preserve the 
 resulting crystals. 
 
 When the assay is opaque, decrepitates long 
 violently, the globule is unchanged on platinum foil, 
 but on charcoal expands, crackles, and is absorbed ; 
 or when on the platinum wire the bead fused by the 
 inner flame gives a violet colour to the outer, the 
 assay is POTASS. But when this is yellow, like that 
 of a candle, SODA. And when at a red heat the 
 platinum foil is corroded, a dull trace of yellow left, 
 and the flame is a beautiful carmine-red, the assay 
 is LITHIA (red with only potass ; yellow with only 
 soda). AMMONIA entirely volatilises. Also, put the 
 red-hot fragments of alkaline minerals on test-paper, 
 and round where they lie will be a blue stain. 
 
 When the assay alone, on charcoal or platinum, 
 is not altered, but with borax effervesces and fuses 
 
BLOW-PIPE ANALYSIS. 95 
 
 into a glass, clear but opaque, by flaming rendered 
 milk white ; also intumescing with mic. salt, and 
 with soda absorbed ; or a bit, held by platinum 
 forceps at the point of inner flame, after some time 
 gives a carmine-red colour to the outer, it is 
 STRONTIAN ; when the flame is not red, it is BARYTES. 
 The globule, with solution of pure nitrate of cobalt, 
 red-brown while hot, colourless when cold, indicates 
 BARYTES ; but black, not melted, STRONTIAN. This in 
 chloride, on platinum wire at the point of the inner 
 flame, causes the carmine colour, which ceases with 
 fusion (thereby distinguished from chloride of lithia, 
 which is constant). 
 
 When the assay alone, on charcoal or platinum, 
 supplies an intensely brilliant light, yet is unaltered, 
 and with borax forms a clear glass, opaque by 
 flaming ; or crystallise when the base is in excess, 
 less milky than with barytes or strontia, with soda 
 infusible, and with mic. salt easily fused into a 
 transparent glass ; or with solution of cobalt dark 
 grey, infusible, the base is LIME. But when with 
 soda no action ensues, with mic. salt the glass is 
 clear but opaque, or milk white, and with solution 
 of cobalt a flesh-red colour, cold by daylight, then 
 
 it is MAGNESIA. 
 
 When the assay alone, on charcoal or platinum, 
 is infusible, yet contracts, also, with borax effer- 
 vescing much, slowly fuses into a transparent glass, 
 not opaque by flaming or cooling ; or with soda 
 merely effervescing, expands, infusible ; or with mic. 
 salt violently effervescing, fuses into a clear glass, 
 not opaque by saturation ; or with solution of cobalt 
 dried, and in inner flame long heated, becomes a fine 
 
96 CHEMISTRY OF POTTERY. 
 
 bright blue, cold by daylight, hot, or by other 
 light a dirty violet, and which becomes only more 
 beautiful in proportion to the quantity of cobalt, the 
 base in ALUMINE. 
 
 When the assay alone, on charcoal or platinum, 
 is infusible, but with borax slowly melts, uneffer- 
 vescent, into clear glass not easily fused, nor opaque 
 by flaming ; or with soda (or charcoal) effervescing 
 fuses into a clear glass ; or with mic. salt and by 
 long heat slowly and only partially dissolves, uneffer- 
 vescing, a portion swimming in the flux a trans- 
 parent inflated mass, the remainder semi-transparent, 
 the glass permanently transparent ; or with little 
 cobalt pale blue, with much black (thus known from 
 alumine), the base is SILICA. 
 
 When the assay alone, on charcoal or platinum, 
 is splendidly brilliant, yet infusible, and with borax 
 or mic. salt dissolves or fuses into a clear or trans- 
 parent glass, milk white by flaming, or excess, not 
 affected by soda, but with solution of cobalt becomes 
 dark grey or black, the base is either GLUCINA, 
 THORINA, YTTRIA, or ziRCONiA (proved by tests, on a 
 precipitate, by a solution of potass, not re-soluble in 
 excess). 
 
 When the assay alone, on charcoal or platinum, 
 is brown-red, infusible, but in inner flame with 
 little borax fuses to glass, yellow-green, hot, colour- 
 less, cold, with much borax, when cold, crystalline 
 enamel, white ; in outer flame orange or beautiful 
 red-hot, pale yellow, cold, or with mic. salt the glass 
 a fine red-hot in outer flame, wholly disappearing 
 in the inner, and colourless and clear, cold, or not 
 affected by soda, which is absorbed, and there 
 
. BLOW-PIPE ANALYSIS. 97 
 
 remains (on the charcoal) a grey-white powder, the 
 base is .CERIUM. 
 
 When the assay, treated as in the preceding 
 process, in the outer flame bubbles, gaseous, and 
 forms a glass of clear amethystine colour, in inner 
 flame without bubbling lost, yet in outer reappearing, 
 or with soda, on charcoal, is not reduced, but on 
 platinum foil fuses into glass, clear-green, hot, blue- 
 green, cold, the base is MANGANESE. 
 
 When the assay alone, on charcoal or platinum, 
 fuses, ignites in blue-green flame and white vapour, 
 or with borax enlarges, then lessens, the flux spreads 
 on the charcoal, or with mic. salt flashes, crackles, 
 and detonates, or as oxide alone, on charcoal, yellow, 
 then white, infusible, brilliantly ignited, and in inner 
 flame white fumes, or with borax or mic. salt a 
 clear glass, by flaming milky, or a white enamel, 
 cold, or round the globule, in inner flame, on the 
 charcoal white powder ; similarly with soda reduced, 
 or with solution of cobalt, a fine green glass, and 
 with copper, the alloy brass, the base is ZINC. 
 
 When the assay alone, on charcoal, in outer 
 flame oxidates black, and in inner reduces grey, 
 infusible, or, a little with borax, or mic. salt, easily 
 fuses into a transparent glass blue, or, with much 
 black, yet red by transmitted light (the mic. salt 
 violet), or, with soda, on platinum, fuses partially, 
 red, hot, grey, cold ; or, on charcoal, in inner flame, 
 without fusing, forms a grey powder, the base is 
 COBALT. 
 
 When the assay alone, on charcoal or platinum, 
 is infusible (arseniate with soda only), but with a 
 little borax fuses, becomes malleable and magnetic ; 
 
 H 
 
98 CHEMISTRY OF POTTEKY. 
 
 or, the oxide alone, in outer flame is black, in inner 
 greenish-grey, or, with borax or mic. salt forms a 
 dark-red glass, lost when cold, in inner flame black 
 opaque, then grey and translucent, or with soda, on 
 charcoal, readily reduces to a white metallic powder, 
 the base is NICKEL. 
 
 When the assay alone, on charcoal or platinum, 
 oxidates, infusible ; or, with mic. salt solely, fuses ; 
 or, as oxide alone, on platinum fuses, but on char- 
 coal, in outer flame is not altered, yet in inner 
 becomes black and magnetic ; or, with borax, or 
 mic. salt, in outer flame forms a glass, dull blood-red, 
 hot, or clear lighter yellow, cold ; or, in inner flame 
 is green, lost when cold, magnetic, or with much 
 borax forms a green glass, or with soda is absorbed 
 and reduced into a dark-brown metallic magnetic 
 powder, the base is IRON. 
 
 But when the assay alone, on charcoal, forms 
 an orange powder, or with borax, or mic. salt, on 
 platinum wire fuses into glass, clear or yellow, hot, 
 colourless or opaque, cold, and on charcoal bubbles, 
 reduces, and sublimes into a yellow powder, the base 
 is CADMIUM. 
 
 When the assay alone, on charcoal or platinum, 
 easily fuses, irridisces, boils, fumes, or as oxides 
 alone, on charcoal, in outer flame becomes black, 
 yellow, and orange, in inner flame is reduced to a 
 yellow coating, then to metallic globules, easily 
 flattened by the hammer, or, with soda, reduced 
 immediately, slightly colouring the flux, or, with 
 borax, on platinum wire easily (mic. salt less easily) 
 forms a glass, yellow, hot, colourless, cold, the base 
 is LEAD. 
 
BLOW-PIPE ANALYSIS. 99 
 
 When the assay alone does not sublime in the 
 glass matrass, but on platinum easily fuses, or on 
 charcoal in outer flame fumes, and a red mark re- 
 mains, lost in inner flame (as are the greenish-blue 
 of antimony and the deep green of tellurium) ; or as 
 oxide alone on platinum in outer flame readily fuses 
 to a brown glass, fine, cold, in inner reduces and 
 perforates the support, or, on charcoal fuses into 
 metallic globules, brittle and refractory, or, with 
 borax in outer flame a grey speckled glass, in inner 
 decrepitates, reduces, and volatilises, or, with mic. 
 salt brownish-yellow, hot, pale, cold, the base is 
 BISMUTH. 
 
 When the assay alone, on charcoal or platinum, 
 by outer flame is not altered, but in inner fuses into 
 a metallic globule, or with borax and mic. salt in 
 outer flame fuses into a glass, fine green, hot, blue- 
 green, cold, in inner dirty brownish-red, lost in 
 charcoal, or with soda on platinum wire in outer 
 flame melts into a glass, fine green, hot, colourless 
 and opaque, cold, or in inner on charcoal is reduced, 
 the base is COPPER. 
 
 When the assay alone, on charcoal or platinum, 
 easily fuses without oxidation, or with soda in inner 
 flame is reduced to a white globule, or with mic. salt 
 in outer flame an opalescent glass, red by candle- 
 light, yellow by daylight, or grey in inner flame ; 
 or as oxide alone is readily reduced, or with borax 
 is partially dissolved, partially reduced in outer 
 flame, a milky glass, grey in inner, or with mic. 
 salt fuses opaque and whitish-yellow, cold, the base 
 is SILVER. 
 
 When the assay, in glass tube, with dry soda, 
 
 H2 
 
100 CHEMISTRY OF POTTERY. 
 
 iron filings, or oxide of lead, by a red heat reduces to 
 a grey powder, or sublimes in the cold part, and 
 by agitation is formed into globules, the base is 
 MERCURY. 
 
 When the assay alone, on charcoal or platinum, 
 is infusible, and not affected by any flux, yet by the 
 cupel is reduced to a grey infusible porous metallic 
 mass, the base is either RHODIUM, PALLADIUM, or 
 IRIDIUM. (The first soluble in nitro-muriatic, the 
 second in muriatic, the third in nitric acid.) 
 
 When the assay alone, gently heated, oxidates 
 and volatilises with a pungent odour, like that of 
 chlorine, the base is OSMIUM. 
 
 When the assay alone, or with any flux, on char- 
 coal does not oxidate, yet fuses without colouring 
 the flame, or in a cupel leaves a grey malleable 
 metallic globule, the base is PLATINUM. 
 
 When the preceding effects occur at a red heat, 
 the base is GOLD. 
 
 When the assay alone, on platinum or charcoal, 
 readily melts, ignites, and oxidates, or, as oxide alone, 
 on platinum in outer flame is yellow, then red, 
 and in inner, ignited, is black, and with soda 
 effervesces without fusing, or, on charcoal, with 
 soda or potash, in inner flame white, reduced easily 
 to a metallic lead readily flattened by the hammer, 
 but with borax or mic. salt difficult to fuse, and form- 
 ing a glass, or which renders a copper bead no longer 
 green, but opaque and brown-red, the base is TIN. 
 
 When the assay alone, on charcoal, ignited, 
 becomes dark brown, on platinum yellow with- 
 out melting, or with borax or mic. salt easily 
 forms glass white by flaming, in inner flame, dull 
 
BLOW-PIPE ANALYSIS. 101 
 
 amethystine ; on charcoal dull yellow, hot, deep blue, 
 cold ; or with soda effervesces, and forms a yellow 
 glass, from outer flame, crystalline, and in cooling 
 evolving much heat ; or with solution of cobalt, 
 grey-black glass, the base is TITANIUM. 
 
 When the assay alone, on charcoal or platinum, 
 easily fuses, and ignited burn with white dense 
 fumes, which around the globule form beautiful 
 pearl-like crystals, or, as oxide alone, on charcoal 
 easily reduces, with a green flame, and on platinum 
 easily melts, or with borax, on charcoal, forms a 
 transparent glass, yellow, hot, lost, cold ; in inner 
 flame grey, opaque, or with mic. salt, on platinum 
 wire, in outer flame with borax, but with soda, in 
 inner flame, reduces, and remains melted, and the 
 white fumes are condensed reticular, the base is 
 
 ANTIMONY. 
 
 When the assay alone, on charcoal or platinum, 
 without smoke or fusion becomes yellow, brown, and 
 black, or, with borax, on platinum wire, in outer 
 flame (on charcoal in inner) fuses easily to a colour- 
 less glass, opaque by flaming, or with mic. salt in 
 inner flame, a blue glass, more beautiful than with 
 cobalt, lost in outer, recovered in inner, or with soda 
 on platinum wire, yellow translucent glass, when 
 cold crystalline, opaque, and yellow, or, on charcoal 
 in inner flame reduces to a brilliant steel-grey 
 metallic powder, the base is TUNGSTEN. 
 
 When the assay alone, on charcoal, is fused, 
 absorbed, and reduced to grey powder, or on plati- 
 num melts in white fumes, in inner flame acidifies 
 blue, in outer oxidates white, then brown, or with 
 borax, on charcoal, in inner flame, fuses, and black 
 
102 CHEMISTRY OF POTTERY. 
 
 scales leave the glass clear, greenish, or, with mic. 
 salt, in outer flame, a glass green, yellow, red, brown, 
 and hyacinth, in succession, in inner, yellow-green, 
 yellow-brown, brown-red, and black, or with soda, 
 effervesces, a glass transparent, red, and paler, cold, 
 the base is MOLYBDENUM. 
 
 When the assay alone, on charcoal or platinum, 
 with a green flame remains unaltered, or with borax, 
 in outer flame forms a glass, bright yellow, or 
 yellow-red ; in inner, greenish, even when cold, or 
 with mic. salt in either flame, a glass emerald-green 
 (but copper, green in only outer), or, with soda, on 
 platinum wire, in outer flame, a glass orange, hot, 
 yellow and opaque, cold; in inner, opaque green 
 cold, absorbed, not reduced, the base is CHROMIUM. 
 
 When the assay alone, on charcoal, in outer and 
 inner flame alternately, readily burns with a blue 
 flame, and strong odour of garlic, or in glass tube 
 with borax and charcoal powder, sublimes and 
 deposits a crystalline or metallic result, the matter 
 is ARSENIC (ACID). 
 
 When the assay alone, in a matrass, sublimes 
 into a grey metallic powder, or, in open tube, a 
 white, or on charcoal a green-edged blue flame, or on 
 platinum melts and fumes, with the odour of putrid 
 horse-radish, or, on charcoal, gently heated, becomes 
 yellow, red, black, is fused, absorbed, and reduced, 
 effervescing and detonating, or, with borax, or mic. 
 salt, a glass on platinum wire clear, on charcoal grey 
 and opaque, or with soda, on platinum wire, colour- 
 less, hot, white, cold ; on charcoal, in inner flame 
 reduced, the base is TELLURIUM. 
 
 When the assay, in an open tube, by outer 
 
BLOW-PIPE ANALYSIS. 103 
 
 flame sublimes into a red powder, the base is 
 
 SELENIUM. 
 
 When the assay, with soda and silica, on char- 
 coal in inner flame render the glass bead dark brown, 
 hot, red, cold, or with soda only, on charcoal, after- 
 wards stains silver black or dark yellow, the matter 
 is SULPHURIC (ACID). 
 
 When the assay, with borax, on charcoal, is 
 fused and transfixed on harpsichord wire, then much 
 heated in inner flame (forming carbonate and 
 phosphate of iron), then the lead, cold, and in paper 
 crushed, a grain of brittle magnetic metal appears, 
 or the assay moistened with sulphuric acid, and 
 by platinum forceps held in inner flame, thereby 
 rendered green, the matter is PHOSPHORIC (ACID). 
 
 When the assay alone, on platinum, is not 
 altered, but, with borax, a glass clear, transparent, 
 opaque, or white-enamel, by flaming, or, with mic. 
 salt, transparent, or, with soda, effervesces and 
 combines, yet neither melts nor reduces, nor is blue 
 with solution of cobalt, the base is COLUMBIUM. 
 
 When the assay alone, on charcoal, without 
 fusing from yellow becomes black, or, with borax, in 
 inner flame forms a greenish glass, with black specks, 
 lost in outer flame, by yellowish-green or brown ; 
 then, in inner flame, green without specks ; or, with 
 mic. salt, or platinum wire, in outer flame, clear 
 glass yellow hot, greenish-yellow cold ; on charcoal, 
 in inner flame, fine green, hot, more beautiful, cold, or 
 with soda, yellow-brown, not dissolved, or reduced, 
 the base is URANIUM. 
 
 When the assay, added to the dark-green bead, 
 formed of mic. salt and oxide of copper, gives to the 
 
104 CHEMISTRY OF POTTERY. 
 
 whole flame a fine blue colour, or a greenish-blue, 
 or a superb emerald -green, or a fine blue purple, the 
 matter respectively is CHLORINE, BROMINE, IODINE, or 
 MURIATIC ACID (rarely sought separately). 
 
 When the assay, with charcoal, fuses and 
 detonates, or without fusing evolves orange vapour, 
 the matter is NITRIC ACID. 
 
 When the assay, with 1 part of fluor spar 
 and 4J parts of bisulphate of potass, on platinum 
 wire, at point of inner flame causes a green halo 
 round the flame, the matter is BORACIC ACID. 
 
 When the assay, in open tube, with mic. salt 
 (mica, etc., best in a matrass), heated a little corrodes 
 the glass, and evolves a peculiar odour, the matter 
 
 is FLUORINE, Or FLUORIC ACID. 
 
 Attention to the appearances will preclude every 
 possibility of error or mistake.* 
 
 * Assaying is also a method of ascertaining the quantity of gold 
 or silver in an alloy. The baser metals are supposed valueless ; 
 and the problem is, simply, how much of the valuable compo- 
 nent is present in the given quantity submitted to the assay. The 
 assaying of gold or silver is divided into two operations ; by one 
 of which they are separated from the imperfect metals, or those 
 easily oxidised ; by the second they are separated from the metals 
 which resist oxidation by simple exposure to the air, and which 
 have, therefore, been called the perfect metals. This second 
 process generally consists in separating gold and silver from each 
 other, as the third perfect metal, platina, is seldom found united 
 to them. 
 
 The method of separating gold or silver from the other metals 
 is founded on the facility with which the latter imbibe oxygen, 
 and the process is calculated to accelerate this operation ; hence 
 the oxide of lead, or litharge, is generally considered as the most 
 powerful purifier of the perfect metals, from the ease with which 
 it parts with its oxygen to the imperfect metals united with them. 
 
BLOW-PIPE ANALYSIS. 105 
 
 But of late oxide of manganese has been found superior to it. 
 In the chemical analysis of metals, the oxide of lead is generally 
 preferred for the above purpose ; but in the assays performed by 
 order of government, metallic lead is always used, probably from 
 the facilities which it is supposed to afford for determining the 
 weight of different ingredients by calculation. The lead in the 
 process first becomes oxidated, then yields some of its oxygen to 
 the other imperfect metals, and afterwards becomes vitrified, in 
 conjunction with the other oxides so formed, and carries them 
 off with it, leaving the perfect metals pure and separate. 
 
 The above operation is called cupellation, and is performed 
 on a flat round cake of bone-ashes, compressed within an iron 
 ring, which is named a cupel ; this is placed in a vessel called a 
 muffle, which resembles a small oven, fixed in a furnace capable 
 of giving a heat sufficient for the fusion of gold, so that its mouth 
 may come in contact with the door, at the side to which it is 
 luted, to separate it from the peal : there are small slits made 
 in the sides of the muffle to afford a passage for the air. 
 
 As by this mode of operation we may certainly lose the ele- 
 ments of the substance examined, and only judge of the nature of 
 the mineral, or other body, by certain appearances which take 
 place during the immediate time of the operation, while propelling 
 the flame of a lamp, when those substances which it is treating sub- 
 limes. To remedy this inconvenience in mineralogical research, 
 and enable the operator to preserve all the elements of any solid 
 substance examined in chemical analysis, when thus separated by 
 this powerful agent, Mr. Gurney contrived a simple apparatus : a 
 solid slab of plaster of Paris or of metal, with its upper surface 
 ground perfectly true, that, a ground glass placed on it, remains 
 .air-tight on the edges, like as on the table of an air-pump. In the 
 centre of the surface of this plate is a little furnace, into which 
 terminates one of the jets belonging to the instrument, by per- 
 forating from the side through the solid part of the slab. Over 
 the furnace fits a ground bell-glass, or part of a large tube, 
 with a cap and stop-cock affixed, and the whole is completely 
 air-tight. To the stop-cock is attached a bladder or silk bag in 
 the usual manner. 
 
 To use this appendage in connection with the blow-pipe, place 
 the substance to be examined into the little furnace ; the jet which 
 perforates the slab screw to the safety apparatus of the blow-pipe, 
 
106 CHEMISTRY OF POTTEEY. 
 
 press the press-board, either by weight or the hand, the gas inflame- 
 at the jet by a taper, and the glass instantly invert over the 
 furnace ; the intense heat of the blow-pipe will fall on the mineral, 
 and the whole of the volatile or gaseous parts will rise, and either 
 be condensed on the inside of the glass, or in the gaseous form 
 pass through the upper stop-tap into the bladder ; thus all the 
 elements will be retained, and may be examined by the proper 
 tests after the action of the instrument has been discontinued. 
 The glass remove, by placing the slab under water, either with or 
 without the safety cylinder and flexible tube attached, without any 
 possible loss of the contents, which may be decanted into smaller 
 vessels for more accurate examination. Any solid substance, 
 whether a mineral or chemical body, may be analysed in the same 
 way, and the most satisfactory results obtained. 
 
 Should the water, formed by the combustion of the oxygen or 
 hydrogen gases, be an objection to the immediate subject under 
 analysis, a mixture of chlorine and hydrogen, in the proportions 
 to form muriatic acid, may be used to produce the flame from 
 the instrument. 
 
[ 107 ] 
 
 HUMID ANALYSIS. 
 
 THE following General Course of Qualitative 
 Analysis, perseveringly pursued through all its 
 details, will be found of inestimable utility, because 
 of the care with which each step of the several 
 processes is particularised, and unremitted attention 
 to accuracy in the elucidations. It is hoped no 
 inconvenience can ensue from employing numerals 
 to supersede many of the repetitions of the names 
 of bases, etc., and of the re-agents which cause 
 the most obvious phenomena in verifying them. 
 
 In each experiment, by employing only a small 
 portion of the material, often will success ensue ; 
 while a large quantity will need more time, and 
 might lead to error and disappointment. 
 
 The first manipulation, and the last when pre- 
 cision is expected, is, to carefully estimate the 
 quantity of the substance. 
 
 A good balance, with grain weights, should be 
 used ; but when the weights used by apothecaries 
 or silversmiths are employed, we reduce them to 
 grains thus : 
 
 Pound. Ounces. Drams. Scruples. Grains. 
 
 1 12 96 288 5760 Drugs 
 
 1 12 Pennyweights 240 5760 Troy 
 
 A sheet of best glazed post paper fold to the 
 size of the scale ; cut into pieces, and with scissors 
 make the edges smooth, and adjust each piece to the 
 same counterpoise ; on this paper weigh the powder. 
 
108 
 
 CHEMISTRY OF POTTERY. 
 
 With mixed shot counterpoise the small crucibles. 
 And a small glass jar, with a counterpoise, is used 
 for great precision, as into it a fluid can be decanted, 
 so as to add only drop after drop when near the 
 equipoise. 
 
 All substances, whether wholly, partially, or not 
 in any degree solicited to separation by pure water, 
 or dilute muriatic, or nitric acid, are formed of 
 component elements, which are classed as BASES, 
 ACIDS, and NON-METALLIC BODIES. 
 
 1. Potash. 
 
 2. Soda. 
 
 3. Lithia. 
 
 4. Ammonia. 
 
 5. Barytes. 
 
 (A) BASES. 
 
 6. Strontia. 
 
 7. Lime. 
 
 8. Magnesia. 
 
 9. Alumine. 
 10. Glucina. 
 
 15. Protoxide of Manganese. 
 
 16. Oxide of Zinc. 
 
 17. Oxide of Cobalt. 
 
 11. Thorina. 
 
 12. Yttria. 
 
 13. Cerium. 
 
 14. Zirconia. 
 
 18. Oxide of Nickel. 
 
 19. Protoxide of Iron. 
 
 20. Peroxide of Iron. 
 
 21. Oxide of Cadmium. 
 
 22. Protoxide of Lead. 
 
 23. Oxide of Bismuth 
 
 24. Deutoxide of Copper. 
 
 25. Oxide of Silver. 
 
 26. Protoxide of Mercury. 
 
 27. Peroxide of Mercury. 
 
 28. Oxide of Gold. 
 
 29. Protoxide of Tin. 
 
 30. Peroxide of Tin. 
 
 31. Protoxide of Antimony, 
 
 32. Oxide of Platinum. 
 
 33. Oxide of Chromium. 
 
 1. Sulphuric a. 
 Sulphurous b. 
 
 2. Nitric a. 
 Nitrous b. 
 
 3. Chloric. 
 
 (B) ACIDS. 
 
 4. Bromic. 
 
 5. lodic. 
 
 6. Phosphoric. 
 
 7. Boracic. 
 
 8. Carbonic. 
 
 9. Silicic. 
 
 10. Chromic. 
 
 11. Arsenic a. 
 Arsenious b. 
 
HUMID ANALYSIS. 
 
 109 
 
 ; (C) NON-METALLIC BODIES. 
 
 12. Chlorine. 14. Bromine. 16. Sulphur. 
 
 13. Fluorine. 15. Iodine. 
 
 Combined with the Metal of a Base. 
 
 When any of these are obtained by a process,, 
 it is verified by several of the following re-agents 
 soliciting it, and supplying distinctive characteristic 
 colours by their Solutions : 
 
 1. Caustic Potash. 
 
 2. Caustic Ammonia. 
 
 3. Carbonate of Potash. 
 
 4. Bicarbonate of Potash. 
 
 5. Carbonate of Ammonia. 
 
 6. Phosphate of Soda. 
 
 7. Oxalic Acid. 
 
 8. Binoxalate of Potash. 
 
 9. Ferrocyanate of Potash. 
 
 10. Bed ditto of Potash. 
 
 11. Chromate of Potash. 
 
 12. Iodide of Potassium. 
 
 13. Hydrosulphuret of Ammonia. 
 
 14. Sulphuretted Hydrogen Gas. 
 
 15. Do. do. Water. 
 
 16. Succinate of Ammonia. 
 
 17. Protosulphate of Iron. 
 
 18. Protochloride of Tin. 
 
 19. Cyanuret of Mercury. 
 
 20. Protonitrate of Mercury. 
 
 21. Tartaric Acid. 
 
 22. Carbazotic Acid. 
 
 23. Hydrofluosilicic Acid. 
 
 24. Sulphuric Diluted Acid r 
 
 25. Diluted Nitric Acid. 
 
 26. Diluted Muriatic Acid* 
 
 27. Chlorides. 
 
 28. Sulphate of Potash. 
 
 29. Muriate of Platinum. 
 
 30. Muriate of Barytes, 
 
 31. Alcohol. 
 
 32. Nitrate of Silver. 
 
 33. Nitrate of Cobalt. 
 
 34. Muriate of Ammonia* 
 
 35. Acetate of Lead. 
 
 36. Nitrate of Barytes. 
 
 37. Acetate of Barytes. 
 
 38. Muriate of Gold. 
 
 39. Metallic Zinc bar. 
 
 40. Metallic Copper bar. 
 
110 CHEMISTRY OP POTTERY. 
 
 PREPARATORY MANIPULATIONS. 
 
 THE following manipulations depend only par- 
 tially on the skill or dexterity of the operator, and 
 hence are very useful. 
 
 (a) When the powder to be used in the analysis 
 is a neutral compound, without the presence of free 
 acid or alkali, make the porcelain mortar warm, and 
 into it put twenty grains of pure hydrate of potash 
 (or of soda, when magnesia is absent), with five 
 grains of the powdered mineral, quickly triturate 
 them with a glass rod, and with a dry feather care- 
 fully clean the whole out into a crucible, and moisten 
 with pure water. 
 
 (b) The mixture put into a silver crucible, and 
 cover closely (or into one of platinum with a cover, 
 which place within a cylindric one of porcelain, also 
 to be closely covered), place in the Lamp furnace,* 
 and gradually raise the temperature to incandescence, 
 in which state keep it not less than eighty minutes 
 (else a repetition may be needed) to fuse the mass 
 into a paste. This, when cool, will be glass, when 
 the chief component is silica, or imperfectly vitrified, 
 with enlarged bulk, when it is alumine ; with the 
 
 * The Lamp furnace of Lowitz will burn either spirit, pyro- 
 acetic acid, or best olive oil. It has two concentric wicks, the 
 outer, two inches, the inner, one inch, in diameter ; a copper 
 chimney, four inches high, and three in diameter, having air-holes ; 
 also a cover adapted to receive a fine silver crucible, that will 
 contain three ounces. (Messrs. Jones, Holborn, supplied that I 
 use, and with its power I am well satisfied.) 
 
HUMID ANALYSIS. 
 
 Ill 
 
 presence of iron indicated by a brown tint ; or man- 
 ganese by a bright grass-green, affecting water ; or 
 chromium, by a greenish-yellow. 
 
 Another lamp furnace is 
 thus described and figured by 
 Mr. Griffin, in a Note in his 
 edition of EOSE'S Manual, 
 page 49: "The spirit-lamp, 
 with circular wick, or double 
 current of air, is one of the 
 most indispensable articles of 
 apparatus of the analyst ; for 
 many accurate experiments 
 cannot be performed without 
 it. The wick passes between 
 two cylinders, which are con- 
 nected below by a horizontal 
 plate, and are raised or de- 
 pressed by means of the toothed wheel e and the toothed bar g. 
 The lower end of the latter is connected with a cross bar, upon the 
 end of which is fastened a ring whereon the wick is stuck. The 
 cross bar works up and down in the box b. This box does not form 
 part of the spirit-holder a, as it does in the common lamps, but is 
 separated from it by the open spaces t t. The spirit passes from 
 a into b by a small pipe, which passes diagonally from the under 
 part of a nearly to the bottom of 6, something in this manner F. 
 The object of this contrivance is to prevent the explosion which 
 frequently takes place when the common spirit-lamps are inflamed, 
 and which is owing to the mixture of atmospheric air and vapour 
 of alcohol which exists in the spirit-holder a. At m is an opening 
 by which the spirit is poured into the lamp. This is afterwards 
 closed by a cork. In the front of the lamp, at s, a piece of glass 
 is cemented, to afford an opportunity of readily ascertaining how 
 much spirit the spirit-holder a contains. The lamp is provided 
 with a copper chimney. The wick must be cut quite level, and 
 must never remain in a charred state. The figure represents a 
 lamp of this sort, drawn according to a scale of one inch and three- 
 quarters to a foot. With a lamp such as this, 380 grains of 
 
112 CHEMISTEY OF POTTEKY. 
 
 (c) Into a porcelain capsule shake the contents 
 before they are cold by gently pressing the sides of 
 the crucible ; fill the crucible with pure water, boil 
 this two minutes, and repeat this till the inside of 
 the crucible is completely washed from the most 
 minute particle of the fused mass, adding each liquid 
 into the capsule. Into a test-tube of this solution 
 drop muriatic acid, and if the tint be orange-red, 
 iron is present ; a purplish-red, manganese ; and a 
 golden-yellow, chromium. Sometimes muriatic acid 
 is employed at first to wash out the crucible, but 
 not only may loss ensue by the effervescence, but 
 when manganese, cerium, or chromium is present, 
 chlorine will evolve, and corrode the platinum 
 crucible. Indeed, platinum vessels must not be 
 used in any process whenever there is present 
 oxide of lead, or of copper with charcoal, or per- 
 oxide of lead or manganese with muriatic acid, or 
 chlorine, or regulus of metals. 
 
 carbonate of soda may be fused in about fifteen minutes, the salt 
 being placed in a platinum crucible of the weight of from 300 to 
 380 grains, and large enough to contain an equal weight of water. 
 A lamp which is incapable of effecting the fusion of at least 180 
 grains of carbonate of soda is unfit for use. The experimental 
 chemist should possess two lamps of this description, one for 
 fusing and another for other experiments. In the latter case the 
 rods which support the lamp may be strong, but for the other 
 lamp the rods may be as thin as possible, in order that they may 
 not carry away too much of the heat." No doubt Messrs. Jones 
 will supply this lamp, perfectly constructed, on as moderate terms 
 as any other philosophical instrument maker. Having had deal- 
 ings with them during twenty years, to a considerable amount, 
 I can with more confidence give an opinion. 
 
HUMID ANALYSIS. 113 
 
 The fact is very remarkable, that by much the 
 greater number of the elements mentioned in 
 page 27 are the productions of the laboratory, and 
 never presented pure by nature. The discoveries and 
 knowledge of other persons makes the student 
 acquainted therewith ; and he desires to know how 
 he can most readily render tangible and obvious 
 the BASES, whose combinations form all subjects of 
 existence, the globe and its numerous and beautiful 
 embellishments. In the contemplation of these sub- 
 jects on such as cannot be brought to the test of 
 experiment the fancy is at full liberty to enjoy itself, 
 to hazard conjectures and supply expositions ; but 
 like procedure must never be attempted with the 
 others of a contrary character, because every person 
 acquainted with the subject could prove the con- 
 jectures erroneous, and the explanations absurd. 
 
 The subsequent general and particular analytic 
 processes carefully detail the best established and 
 most general methods by which the student can 
 perform, with the greatest probability of success, the 
 numerous nice and delicate experiments which are 
 adapted to supply intimate acquaintance with the 
 relations of substances to each other reciprocally, 
 their mutual dependence, and connection as a whole ; 
 and also the laws by which all the phenomena are 
 governed and can be explained. 
 
 The combinative potency of pure water, muriatic 
 and nitric acids, concentrated or diluted, will suggest 
 the most successful processes for separating sub- 
 stances, whether binary or mixed compounds, into 
 their respective component elements. They, there- 
 fore, shall be elucidated agreeably to their characters. 
 
114 CHEMISTRY OF POTTEEY. 
 
 CLASS I. Many substances, binary compounds, 
 whose component elements are only a base and an 
 acid a metal and a now metallic body (as chlorine 
 in chlorides, fluorine in fluorides, cromine in 
 cromides, iodine in iodides, and sulphur in sul- 
 phurets) are completely separable into those 
 elements by a sufficient quantity of pure water. 
 
 CLASS II. Many such binary compounds, by 
 pure water only partially separable, are completely 
 so by muriatic or nitric acid. 
 
 CLASS III. Many binary compounds are wholly 
 inseparable by pure water, muriatic, or nitric acid, 
 as chloride of 25, protochloride and sulphuret of 
 26, and sulphurets of 5, 67, 22 ; also many acid, 
 phosphates, and some acid arseniates, after long 
 incandescence. 
 
 CLASS IV. Many mixed compounds of two 
 or more bodies are completely separable by pure 
 water. 
 
 CLASS V. Many such mixed compounds, only 
 partially separable by pure water, are completely so 
 by muriatic or nitric acid. 
 
 CLASS VI. Many mixed compounds are only 
 partially separable -by pure water, muriatic, or nitric 
 acid, and the residue are substances separable by 
 only certain processes. (See III. above.) 
 
HUMID ANALYSIS. GENERAL PROCESSES. 115 
 
 GENERAL ANALYTIC PROCESSES. 
 
 CLASS I. Compounds soluble in Water. 
 
 TO FIND THE BASE. 
 
 1. THE compound treat with pure water till it 
 is completely separated ; afterwards concentrate by 
 evaporation till there is the commencement of a 
 pellicle on the surface. To a small portion of this 
 liquid in a test-tube drop muriatic acid, and if a 
 white precipitate fall, nitric must be substituted for 
 muriatic acid in the next manipulation. 
 
 2. The solution slightly acidulate (to redden 
 litmus test-paper), to completely saturate and pre- 
 pare the solvent for tests. 
 
 A. 3. Add test 15 till the liquid gives out the 
 odour. Where there is no precipitate the base is in 
 1 to 19 inclusive, but it is in 20 to 33 when there is 
 one. When this is black, the base is in 22 to 28, 
 thus determined : 
 
 (1.) Into several test-tubes pour a little of the 
 liquid, and whenever the first directed test is in- 
 efficient, proceed to the next, and so in succession, 
 with each of the others, until some definite charac- 
 teristic appears. 
 
 a Into one tube drop test 2 ; a deep-blue tint, 
 without precipitate, not changed by excess of the 
 test, shows the base 24, DEUTOXIDE OF COPPER. To 
 verify this, redissolve the precipitate in muriatic 
 acid, and the diluted solution will supply precipitates 
 
 of the specified colours : 1, 3, blue ; 2, green ; 
 
 i 2 
 
116 CHEMISTKT OF POTTEKY. 
 
 4, 5, 6, 7, greenish ; 9, 11, red-brown ; 10, yellow- 
 green ; 13, 14, 15, black; 12, white; 36, black 
 coating ; 38, orange-red. 
 
 6 To the liquid add much water, and a milky 
 fluid shows the base 23, OXIDE OF BISMUTH ; which, 
 as above directed, verify : 1, 2, 3, 4, 5, 6, 9, white ; 
 7, crystalline ; 10, yellowish ; 11, yellow ; 12, brown ; 
 13, dark brown; 14, 15, black; 36, black spongy 
 mass. 
 
 c lnto the liquid drop test 26, and a white 
 precipitate, insoluble by dilution, shows base 25 or 
 26 ; thus discriminated : Into the liquid (1) drop 
 test 2 ; a precipitate black, and weaker by excess of 
 test, or, in the aciduline liquid, an insoluble grey 
 precipitate, shows the base 26, PROTOXIDE OF MER- 
 CURY; thus verified 1, 2, 4, 5, 13, 14, 15, black; 
 3, dirty yellow ; 6, 7, 9, 26, 27, white ; 10, red- 
 brown ; 11, red; 12, greenish-yellow. But no 
 precipitate in the aciduline liquid by test 2, yet by 
 it in dilute liquid, a brown one, soluble in excess, 
 shows the base 25, OXIDE OF SILVER ; thus verified 
 
 I, 2, brown; 3, 4, 5, 7, 9, 12, 17, 18, 26, 27, white ; 
 6, yellow; 10, 11, red-brown; 13, 14, 15, black; 
 36, black beneath white. 
 
 d To the liquid add test 1 ; a yellow precipitate 
 
 shows base 27, PEROXIDE OF MERCURY ; thus verified 
 
 10, yellow ; 2, 5, 6, 7, 9, white ; 3, 4, red-brown ; 
 
 II, yellowish-red ; 12, cinnabar-red ; 13, 14, 15, 
 black. 
 
 Into the liquid drop test 17 ; a brown metallic 
 precipitate shows base 28, OXIDE OF GOLD ; thus 
 verified 1, 14, 15, 20, black; 2, 5, yellow; 7, 
 greenish-black; 9, emerald-green; 12, yellowish- 
 
HUMID ANALYSIS. GENERAL PROCESSES. 117 
 
 green ; 13, dark brown ; 17, first blue, then brown ; 
 18, red purple. 
 
 f Into the liquid drop test 24 or 25 ; a white 
 precipitate shows base 22, PROTOXIDE OF LEAD ; thus 
 verified 1, 2, 3, 4, 5, 6, 7, 9, 24, 25, 26, 27, white ; 
 11, 12, yellow; 13, 14, 15, black; 36, blackish-grey 
 spangles. 
 
 (2.) When the precipitate, 3, is milk white, the 
 base is 20, PEROXIDE OF IRON ; thus verified 1, 2, 3, 
 4, 5, red-brown ; 6, white ; 9, blue ; 13, black. 
 
 (3.) A yellow precipitate, 3, shows the base 30 
 or 21, thus discriminated : by ammonia neutralise 
 the aciduline liquid ; 
 
 ^To the liquid add test 13 ; a yellow precipitate, 
 insoluble in excess of the test, shows the base 21, 
 OXIDE OF CADMIUM ; thus verified 1, 2, 3, 4, 5, 6, 
 7, 9, white; 10, 13, 14, 15, yellowish; 36, grey 
 spangles. But a soluble precipitate shows base 30, 
 PEROXIDE OF TIN, thus verified 1, 2, 3, 4, 5, 6, 
 white ; 13, yellow. 
 
 (4.) A dark brown precipitate, 3, shows the base 
 29, PROTOXIDE OF TIN ; thus verified 1, 2, 3, 4, 5, 
 6, 7, 9, 10, white ; 11, white flocculent ; 13, brown. 
 
 (5.) An orange-red precipitate, 3, shows the base 
 31, PROTOXIDE OF ANTIMONY ; thus verified 1, 2, 3, 
 4, 5, 6, 7, 9, white ; 13, red. 
 
 B. 4. When the solution, 2, is indifferent to the 
 solicitings of sulphuretted hydrogen (test 15), neu- 
 tralise by ammonia (test 2) ; then add hydrosulphuret 
 of ammonia (test 13), and when there is no precipi- 
 tate the base is in 1 to 8, but in 9 to 19 when there 
 is one. When this is black, the base is in 17 to 19, 
 thus determined : 
 
118 CHEMISTRY OF POTTERY. 
 
 (1.) Into the liquid drop test 3 ; a precipitate 
 a In succession white, green, and brown-red at the 
 
 surface, shows the base 19, PROTOXIDE OF IRON ; 
 
 thus verified 1, 2, 3, 4, 5, 6, white ; 7, 8, yellow ; 
 
 9, 10, blue. Dirty red shows the base 17, OXIDE OF 
 COBALT ; thus verified 1, 2, 6, blue ; 3, 4, 5, red ; 9, 
 green ; 10, red brown. Bright green shows the base 
 18 ; OXIDE OF NICKEL ; thus verified 1, 3, 4, 5, 7, 
 
 10, green ; 6, 9, white. 
 
 (2.) A flesh red precipitate, 4, shows the base 
 15, PROTOXIDE OF MANGANESE ; thus verified 1, 2, 3, 
 4, 5, 6, white ; 7, white crystalline ; 9, white or pale 
 red ; 10, brown. 
 
 (3.) A white precipitate, 4, shows the base 16 
 or 9, thus discriminated : b Into the liquid drop 
 test 2 ; a white precipitate, in excess of test soluble, 
 shows the base 16, OXIDE OF ZINC ; thus verified 
 1, 2, 3, 4, 5, 6, 7, 9, 14, 15, white ; 10 yellowish-red. 
 But one insoluble, shows the base 9, ALUMINE ; thus 
 verified 1, bulky ; 2, 3, 4, 5, 6, very voluminous. 
 An insoluble one, which dissolves by test 5, shows 
 the base 10, GLUCINA ; thus verified 1, 2, 3, 4, 6, 
 copious ; 13, slight. 
 
 C. 5. When neither tests 15 nor 13 solicit a 
 precipitate in the aciduline solution, 2, to the neutral 
 solution, 4, add test 3 ; a white precipitate shows the 
 base in 5 to 8. 
 
 (1.) "Into the liquid drop test 2; a white floc- 
 culent precipitate shows the base 8, MAGNESIA (not 
 appearing in an aciduline liquid) ; thus verified 1, 
 3, voluminous ; 2, bulky ; 6, very slight. 
 
 (2.) The liquid put into a lead capsule, and drop 
 into it test 23, and leave 8 days to repose. A preci- 
 
HUMID ANALYSIS. GENERAL PROCESSES. 119 
 
 pitate shows the base 5, BARYTES ; thus verified 
 1, voluminous ; 3, 4, 5, 6, 24, white, copious ; 16, very 
 quick. But no precipitate shows the base 7 or 6, 
 thus discriminated : b The solution, 5 or 2, dilute 
 much ; add test 28 or 24 ; an immediate precipitate 
 shows the base 6, STRONTIA ; thus verified 1, 4, 5, 6, 
 24, white ; 7, 8, troubled. But sluggishly a crystal- 
 line precipitate shows the base 7, LIME ; thus 
 verified 1, 3, 4, 5, 6, 7, 8, white. 
 
 D. 6. When the aciduline solution, 2, is indif- 
 ferent to the tests 15, 13, and 3, the base is in 1 to 4. 
 a Over it, near, hold a glass rod, moistened with test 
 26, and white vapours or, on dropping into it 
 test 1, the odour of ammonia shows the base 4, 
 AMMONIA ; thus verified 21, crystalline, 23, copious; 
 29, bright yellow. 
 
 b When the two last fail, add test 29 ; a yellow 
 precipitate shows the base 1, POTASH ; thus verified 
 21, white crystalline ; 22, bright yellow crystalline ; 
 23, transparent, gelatinous. When there is no 
 precipitate the base is 2, SODA ; by 23, opalescent. 
 The aciduline solution, 2, neutralise by am- 
 monia ; add test 6 ; a copious, sluggish precipitate 
 shows the base 3, LITHIA ; thus verified 28, copious 
 29, little troubled ; 4, very sluggish, but fine. 
 
120 CHEMISTKY OF POTTERY. 
 
 TO FIND THE ACID OR THE NON-METALLIC SUBSTANCE. 
 
 E.jj 7. WHEN in the first solution, 2, test 26 
 causes effervescence, either acid 8 or sulphur com- 
 bined with a metal of one of the bases is present. 
 When the evolving gas is inodourous, it proves the 
 presence of acid 8, CARBONIC ; but when odourous 
 the solution contains a sulphuret. 
 
 F. 8. When test 26 does not cause effervescence, 
 neutralise the solution, and by evaporation concen- 
 trate. Add test 29 ; a white precipitate shows the 
 acid is 1, or 6, or 11, or 7 ; or that 13 is combined 
 with a metal of one of the bases, thus determined : 
 
 (l.) a The precipitate treat with test 26, and no 
 change ensues when acid 1 is present, SULPHURIC ; 
 thus verified 30, 3 (boiled in), solicits, and forms an 
 insoluble compound. 
 
 (2.) When separation of the precipitate ensues, 
 6, 11, 7, or 13, combined with a metal of one of the 
 bases, is present. b In a leaden capsule put a little/) f 
 the powder, 1 ; add test 24, cover with glass-plate, 
 previously warmed, and well-coated with bees'-wax, 
 through which distinctly are traced to the glass 
 whatever lines may be thought proper ; raise the 
 temperature a little, again reduce it, examine the 
 glass, and when its surface is corroded in the tracings, 
 the compound is a fluoride, and as such must be 
 analysed. 
 
 c When the glass is not corroded, moisten with 
 test 24, next add test 31, inflame, and a green blaze 
 shows acid 7, BORACIC ; thus verified to the solu- 
 tion 1, add test 20, 32, white precipitate, 30 soluble. 
 
HUMID ANALYSIS. GENERAL PROCESSES. 121 
 
 Moisten with test 26, next add test 15, and 
 boil; a yellow precipitate shows acid 11, ARSENIC; 
 thus verified 32, brown ; but when there is no 
 precipitate, acid 6, PHOSPHORIC, is present ; thus 
 verified 30, 35, white; 32, yellow. 
 
 (3.) To the solution add test 32 ; a white floccu- 
 lent precipitate, insoluble in dilute nitric acid, shows 
 a chloride of the metal of one of the bases ; thus 
 verified 24, muriatic acid gas evolves. 
 
 (4. ) Strew the powder on red coals ; increased 
 combustion with deflagration show acid 2, NITRIC ; 
 thus verified 17, crystals ; 24, dark brown. 
 
 (5.) To the solution add test 26; a red-brown 
 tint shows acid 5, IODIC ; thus verified 14, 24, 
 greenish-yellow vapours ; or 24 (heated), violet 
 vapours. 
 
 (6.) To the solution add test 20 ; a yellowish 
 precipitate shows acid 4, BROMIC ; thus verified 
 32, white ; 24, hyacinth -red vapours. 
 
122 CHEMISTRY OF POTTEEY. 
 
 CLASS II. Compounds soluble only in Acids. 
 
 TO FIND THE BASE OR THE METAL. 
 
 1. When the powder contains a sulphuret, or 
 base 22, or 25, or 26, form the solution with nitric 
 acid, raising the temperature ; but other solutions, 
 form with muriatic acid, and raised temperature 
 when required. 
 
 2. In several test-tubes put a small portion of 
 the solution, and dilute. Add test 15 ; a precipitate 
 shows the base in 20 to 33 ; which determine, and 
 verify as already directed, Class I., A. 3. 
 
 A. (1.) When acid 11 is present, keep its sul- 
 phuret in the acid at 120 several days, the test 14 
 strongly soliciting the precipitate ; this must be 
 filtered out as quickly as possible ; boil the liquid, 
 the precipitate try by blow-pipe for metallic arsenic* 
 Metallic oxides are quickly precipitated with char- 
 acteristic colours. 
 
 B. (2.) When test 15 fails, alkalinise by test 2; 
 then add test 13 ; a precipitate becoming black 
 shows the base 17 to 19 ; thus determined (and in 
 every instance to be verified as before directed) : 
 a On platinum foil, with a flux and blow-pipe, fuse the 
 powder ; the assay blue, shows the base 17; red, 18 ; 
 deep red, 19. To the acid solution add test 9 ; green, 
 17 ; white, 18 ; blue shows the base 19. 
 
 (3.) A flesh-red precipitate (2.), or one which 
 becomes so, shows base 15. 
 
 (4.) A white changeless precipitate shows the 
 
HUMID ANALYSIS. GENERAL PROCESSES. 123 
 
 base 16 or 9 (except acid 6 or 7 is combined with 
 bases 8 to 5, or these combined with 13) ; thus 
 discriminated : 
 
 6 The powder mix with soda, or moisten with 
 test 33, and on charcoal subject to the inner blow- 
 pipe flame ; which white changing into green, shows 
 the base 16. Also, when test 2 causes a precipitate, 
 soluble in excess ; or this by test 13 is insoluble in 
 tests 1 and 2. 
 
 c The powder moisten with test 33, and subject 
 to the inner blow-pipe flame ; a blue assay shows 
 the base 9 ; also, when the precipitate (2.) is and 
 continues soluble in test 1. 
 
 d The acid solution, dilute ; add test 24 ; a white 
 precipitate ; or add test 23, and leave twenty-four 
 hours to repose ; a precipitate in both instances shows 
 base 5 ; but no precipitate by either process shows 
 base 6. Or, add test 31 ; a white precipitate shows 
 base 7 ; but no precipitate, the base is 8 ; also when 
 the powder, moistened with test 33, on charcoal 
 subjected to inner blow-pipe flame, gives a pale red 
 assay. 
 
 C. 5. When tests 15 and 13 fail to cause a 
 precipitate, to solution d add excess of test 3 ; a 
 precipitate, either sluggish or by long boiling, 
 shows the base in 8 to 5 ; thus determined : 
 
 a To dilute solution add tests 24 or 28 ; a preci- 
 pitate shows base 6 ; or 5 when test 23 renders it 
 white after many hours repose. But when there is 
 no precipitate by these alkalinise by test 2, then add 
 test 34 ; also, add test 8 ; a white precipitate shows 
 base 7. Or, when 34 and 8 fail, add test 6, a white 
 precipitate shows base 8. 
 
124 CHEMISTEY OF POTTEEY. 
 
 TO FIND THE ACID OR NON-METALLIC BODY. 
 
 D. 6. The powder moisten with muriatic acid ; 
 gently heat ; and effervescence and gas, without 
 odour, prove the acid 8 ; but sulphur and a metal 
 when offensively odourous. 
 
 a When there is excess of base, by F. 8 (4.), seek 
 the presence of acid 2. 
 
 6 The powder mix with soda, fuse on platinum 
 foil in blow-pipe inner flame ; a garlic odour proves 
 acid 11. Processes F. 2. b c will detect a fluoride and 
 a borate. d In cold nitric acid dissolve the powder ; 
 dilute, add test 32 ; a white precipitate shows 
 a chloride, e Heat this solution ; reaction ensues 
 during the evolving of nitrous acid vapour, with 
 deposit of sulphur by long digestion ; dilute ; add 
 test 36 ; a white insoluble precipitate proves a sul- 
 phuret present. When this is of base 26, 29, or 31 
 (but not of base 22), the solvent must be nitro- 
 muriatic acid, and chlorine gas will evolve, the 
 result being respectively the sulphate, the peroxide, 
 and the protoxide. f When the substance has excess 
 of base, to the dilute muriatic solution add test 30 
 (to the nitric, test 36) ; a white insoluble precipitate 
 proves acid 1 ; which verify, as before directed. 
 g The powder mix with protoxide of lead, base 22 ; 
 and on charcoal, fuse by blow-pipe flame ; the assay 
 crystallising while cooling shows acid 6. Likewise 
 verify ; with test 30 and 36 white, 32 yellow. 
 
HUMID ANALYSIS. GENEEAL PBOCESSES. 125 
 
 CLASS III. Compounds not soluble in Water or Acids. 
 
 TO FIND THE BASE. 
 
 1. THE powder mix with soda, or moisten with 
 test 24 ; on charcoal, the blow-pipe flame green, 
 proves acid 6. Phosphates and arseniates boil in 
 concentrated sulphuric acid, and add pure water ; 
 only when the base is 5, 6, 7, or 22, these all being, 
 though unequally, insoluble in water. 
 
 2. a The powder throw into nitro-muriatic acid ; 
 the deposit is 16, SULPHUR ; add test 30 ; an insoluble 
 precipitate shows sulphuret of base 26 ; with test 1 
 a yellow precipitate shows it of 27. b Mix the powder 
 with soda ; in a test-tube heat, and metallic mercury 
 appears ; heat the powder alone, and the assay will 
 be red, whether the base be 26 or 27. 
 
 3. The powder moisten with test 13 ; the white 
 changing to black proves the base 22 or 25 ; with 
 acid 3 ; thus discriminated In glass tube over the 
 lamp heat the powder ; sublimation proves proto- 
 chloride of 22 ; fusion, chloride of 25 ; indifference, 
 sulphate of 22. 
 
 4. In water digest the powder ; to a portion of the 
 liquid add test 30, to another, test 8 ; white precipitates ; 
 the former, insoluble in acids, prove sulphate of base 7. 
 
 5. The powder digest in test 3 ; filter, acidulate 
 with test 26 ; add test 30 ; an insoluble precipitate 
 proves a sulphate of base 5 or 6 ; thus discriminated 
 the aciduline liquid filter, concentrate, add test 31, 
 inflame ; a red flame shows sulphate of base 6, and of 
 5 when not red ; or, in leaden capsule add test 23 ; 
 no precipitate proves base 6 ; as base 5 is showed by 
 one white and extremely sluggish. 
 
126 CHEMISTKY OF POTTERY. 
 
 CLASS IV. Mixed Compounds soluble in Water. 
 
 TO FIND THE BASES. 
 
 PROCEED as directed (1, 2, Class I.) to acidulate 
 the watery solution. 
 
 A. 1. Add test 15, and warm the liquid ; a 
 precipitate proves the bases in 21 to 33 (or 20 when 
 white and milky, or with acid 11, when yellow, 
 soluble in test 13). When precipitation ceases, care- 
 fully decant, and preserve the liquid for testing. 
 
 (1.) The precipitate moisten with test 2, then 
 add test 13 ; entire disappearance proves the bases 
 in 28 to 31, thus determined : a The diluted solution 
 acidulate with test 26 ; the precipitated sulphurets, 
 peculiar in tint (paler because of the sulphur present), 
 thus discriminate : b To the dilute liquid add test 
 18 (or 17), a red-purple (or a brown) metallic preci- 
 pitate proves the base 28. c To the dilute liquid add 
 tests 9, 10, or 11 ; a white, flocculent precipitate 
 shows the base 29. The very dilute liquid, milky, or 
 supplying a red precipitate, proves the base 31, or 30 
 when yellow. Or, rf the precipitate (1.) mix with 
 soda, and, on platinum foil, fuse in the blow-pipe 
 inner flame a smoke off the assay, and then 
 reticular crystals, show the base 31, not 30. 
 
 (2.) Indifference to tests 2 and 13 shows the 
 base in 21 to 27. a Dilute the solution much, filter 
 out, and preserve whatever is insoluble, then acidulate 
 with test 26 ; a milkiness shows test 13 entirely 
 inefficient to separate anything, as does complete 
 
HUMID ANALYSIS. GENERAL PEOCESSES. 127 
 
 evaporation. b The precipitate on filter wash well ; 
 digest filter and contents in concentrated nitric acid, 
 and the sulphur (yellow precipitate) filter out. The 
 strong acid separates the sulphuret of mercury. Mix 
 the powder with soda, and in a test-tube, by 
 blow-pipe heat, sublime ; no change proves the base 
 27 ; change to a grey powder, by trituration rendered 
 metallic, shows the base 26. c The sulphur ( b ) may 
 have present sulphate of lead when the base 22 was 
 in combination, though most of it would be separated 
 by the nitric digestion. d The acid solution alkalinise 
 with test 2 ; a blue tint shows the base 24. e Add 
 test 26 ; a white precipitate, disappearing in test 2, 
 shows the base 25. f The diluted solution treat with 
 test 24 ; a white precipitate shows the base 26. 
 9 Much of the acid dissipate by evaporation, add pure 
 water in excess ; a milky liquid proves the base 23. 
 h The powder mix with soda, and on charcoal, in 
 blow-pipe inner flame, a brownish-red (not yellow) 
 assay proves the base 21. 
 
 B. (2.) On platinum foil evaporate two drops of 
 the liquid A. 1. ; complete evaporation proves the 
 absence ; but a residue, one or more in 19 to 9, of 
 fixed bases. 
 
 (1.) "The liquid alkalinise with test 2; add test 
 13 ; the precipitate filter out, and wash well with 
 water, odourated with test 13. b The precipitate and 
 filter digest in test 26 till inodourous of test 14. 
 When base 18 or 17 is present, add test 25 ; 
 filter, and the precipitate digest in nitric acid ; add 
 test 2, the precipitate filter, wash well ; white shows 
 the base 9, brown 9 and 20 ; thus discriminated : 
 c In test 26 dissolve the filter and its contents ; filter ; 
 
128 CHEMISTEY OF POTTEBY. 
 
 to liquid add test 1 ; a precipitate proves the base 
 20 ; indifference proves it 9, as will a white precipi- 
 tate on adding test 34. "The test 3 will give a 
 white or a red-brown tint to the precipitate, as the 
 base is 19 or 20. 
 
 (2.) The liquid (1 ft ) with a blue tint, proves the 
 base 18 ; rose-red, or a blue assay in blow-pipe flame, 
 the base 17. "To the solution add test 1 ; a pre- 
 cipitate bright apple-green shows the base 18, but 
 brown by the atmosphere the base 15 ; also this 
 discriminated by the blow-pipe flame when mixed 
 with soda and fused on charcoal, a white metallic 
 magnetic assay, 18; on platinum foil, the assay, 
 amethystine or green, 15. b To the liquid last left 
 add test 13 ; the precipitate roast on charcoal by 
 the blow-pipe ; the assay, amethystine or green, 
 proves the base 15 ; white powder, 16, also green, 
 with test 32 ; and 17 grey magnetic powder. 
 
 C. On platinum foil evaporate two drops of the 
 solution B. 2, and cease when all disappears ; but a 
 residue may have the fixed bases 8 to 1 (except 4). 
 
 (1.) a Acidulate with test 26 ; by heat dissipate 
 test 14 ; filter out the sulphur ; alkalinise by test 
 3 ; by heat dissipate acid 8 ; a precipitate is in 7 to 5. 
 6 The precipitate dissolve in test 26 ; add test 28 or 
 24 ; an immediate precipitate maybe of all three ; a 
 sluggish one only 7 ; thus determined : c The dilute 
 alkaline liquid acidulate with test 24 ; warm ; filter ; 
 then alkalinise the liquid with test 2, and add test 7 
 or 8, for base 7, with twenty-four hours repose. 
 When 7 appears the precipitate with test 24 also 
 contains it ; but otherwise this precipitate contains 
 both of either of 6 and 5 ; thus discriminated : d In 
 
HUMID ANALYSIS. GENEKAL PKOCESSES. 129 
 
 a leaden capsule to the solution ( a ) add test 23 ; a 
 very sluggish precipitate is base 5 ; but 6 when there 
 is none. e The precipitate ( c ) heat long on charcoal 
 in blow-pipe inner flame ; then dissolve in test 26, 
 and evaporate dry on platinum foil ; the residual salt 
 place on a wedge-shaped strip of paper, moisten with 
 test 31, alcohol, inflame ; red proves base 6 present 
 (or with 5 also) ; absent when not red ; find 5 by 
 process d . 
 
 (2.) The liquid after (1 a ) on platinum foil evapor- 
 ate ; when all flies off, cease ; when there is a residue : 
 a To the liquid add test 6 ; a white precipitate 
 proves 8 present. When there is no precipitate : 
 b In a porcelain capsule evaporate dry, and, by heat, 
 dissipate all salts with test 2 ; in diluted test 31 
 mix or separate the powder ; add test 29 ; a bright 
 yellow precipitate proves base 1 ; when there is no 
 precipitate base 2 may be present, as also with the 
 other ; thus determined : c A little of the powder 6 
 on platinum wire in blow-pipe inner flame, is blue 
 for base 1, yellow for 2, or 1 and 2 together. For 3 
 proceed as before (1. D. 6. c ). 
 
 d The liquid (2 a ) evaporate, the residue ignite ; 
 acidulate with test 37 ; the precipitate filter out, and 
 verify by the blow-pipe. * The liquid (with excess of 
 acetates of bases 5, 8, 1, and 2, present) evaporate 
 dry, and the residue ignite, and dissolve in water ; 
 the latter two when present do not precipitate as do 
 the former two. 'By heat dissipate acid 8, and the 
 base 8 remains, caustic but insoluble. To the alkalies 
 add test 26, and the resulting chlorides discriminate 
 as before. g Heat the powder (A. 1.) in test 1 ; hold 
 
 over it a rod moistened with test 26, to prove base 4. 
 
 K 
 
130 CHEMISTRY OF POTTEEY. 
 
 TO FIND THE ACIDS, ETC. 
 
 A. 1. a To a portion of the concentrated solution 
 (A. 1) add test 26; effervescence and inodourous 
 gas prove acid 8 present and 16 absent ; but 
 odourous prove a sulphuret of a metal, and 8 may 
 also be present. b To another portion (not acid) add 
 test 30 (when bases 22, 25, 26 are absent, otherwise 
 test 36) ; a precipitate proves there may be present 
 13, 6, 7, 11 (and 8 when test 30 is used). c When 
 proper employ diluted nitric acid, else add test 26 ; 
 the resulting precipitate is soluble when acid 1 is 
 absent. The precipitate dissolves, effervesces, and 
 remains soluble when the liquid is aciduline, boiled, 
 and alkalinised by test 2, for acid 8 alone. When 
 test 2 troubles the liquid, 8 may be present with one 
 of the other acids. The absence of phenomena 
 intimates there is one, if not all of 6, 7, 11, and 8. 
 
 (2.) a In a leaden capsule put some of the powder ; 
 add test 24, and cover with waxed traced glass ; 
 corrosion proves 13. 6 Add tests 24 and 31, inflame, 
 a green tint proves acid 7. c To the solution (1 a ) 
 add test 15 ; a precipitate proves acid 11 (present 
 only with alkalies when soluble, and only soluble 
 when in excess combined with earths and metallic 
 oxides ; hence no oxide will discolour its precipi- 
 tates). d To the solution add test 30 ; a precipitate, 
 soluble in tests 26 or 25, but again appearing when 
 treated with test 2, proves acid 6. 
 
 (3.) "The solution alkalinise with test 15, boil, 
 filter out the sulphuret of acid 11 ; neutralise with 
 
HUMID ANALYSIS. GENERAL PROCESSES. 131 
 
 test 2 ; add test 30 ; a precipitate, insoluble in pure 
 water, proves acid 6, or 7 if soluble. (4.) To the 
 powder, in a platinum capsule, add test 24 ; by heat 
 dissipate all vapour ; the residue mix in water, 
 acidulate with test 26 ; add test 30 ; filter out the 
 precipitate (sulphate of base 5) ; add test . 2 ; a 
 precipitate proves acid 6 present. (5.) When the 
 precipitate (4) is not completely soluble in tests 26 
 or 25, the acid 1 is present ; and the liquid after 
 filtering treat as just directed for 4, 6, 7, 11. 
 (6.) To solution add test 32 ; a white solution, 
 insoluble in test 25, proves a chloride present. 
 (7.) Throw powder on glowing coals ; deflagration 
 proves acid 2 present. 
 
132 CHEMISTEY OF POTTERY. 
 
 CLASS V. Mixed Compounds soluble in Acids. 
 
 TO FIND THE BASES. 
 
 A. 1. The powder mix well in pure water ; 
 filter, and the watery solution treat as already 
 directed in Class IV. 
 
 2. The filtered portion dissolve in the proper- 
 acid. "This solution alkalinise with test 15; filter 
 out the precipitate. ft To the liquid add test 13 ; a 
 precipitate proves bases 30 or 31, or acid 11. (Verify 
 each result as before.) To discriminate these : c By 
 the blow-pipe flame and odour prove acid 11. d The 
 precipitate moisten with water ; add test 26, and 
 solution will ensue when base 31 is present with 
 sulphur. 'The liquid (*) dilute; add test 26; the 
 precipitate filter out, dry, and in closed glass tube, 
 by heat sublime the sulphur and any sulphuret of 
 arsenic. In the minimum of sulphur remain the 
 sulphurets of bases 30 and 31. This minimum treat 
 with test 26, next dilute ; add test 38 ; a purple 
 precipitate proves the base 30, and the base 31 when 
 the liquid is troubled and a brown precipitate 
 appears. ^That portion of the precipitate ( a ) 
 may contain bases 21 to 27. and must be treated 
 by the processes IV. A (2). 
 
 B. By processes IV. B. ascertain the presence 
 or absence of fixed bases. 
 
 When present, a alkalinise with test 2, add test 
 13 ; a precipitate is in 20 to 9, also in 8 to 5 when 
 with acid 6 or 7, or a metallic base is combined with 
 
HUMID ANALYSIS. GENERAL PEOCESSES. 133' 
 
 13. Employ the proper acid for digesting the pre- 
 cipitate. b The acid solution filter (warm, when 
 employing nitric acid) ; add test 24 ; a precipitate is 
 sulphurets of 6 or 5 (or 7 when in excess) ; filter, 
 wash the precipitate ; whatever dissolves is base 7, 
 which test 7 or 8 will verify ; the residue is 6 or 5, 
 which by the blow-pipe flame discriminate, as pre- 
 viously directed. When no phenomena indicate base 
 6, 5 only is present, as also it may be along with 6, 
 c The precipitate boil in test 3 ; after 24 hours' repose, 
 decant the liquid, and to the deposit add test 26, 
 to which add test 23 for base 5, and for base 6 
 test 24. a Take liquid from filter ( b ) ; add test 2 to 
 alkalinise ; a precipitate is base 20 or 9 (or 8 .when 
 with acid 6). e This precipitate digest in test 1, 
 which will dissolve base 9, but not base 20, or base 8 
 with minimum of acid : filter ; f the liquid treat 
 with test 34, and a precipitate is base 9 ; 9 the 
 deposit ( ) examine for base 20 by the blow-pipe ; 
 or dissolve in test 26, then alkalinise with test 2, and 
 a precipitate is base 20 ; the liquid may have base 8 
 present, and will to test 6 supply a precipitate. The 
 liquid ( d ) may have present bases 18 to 15, which 
 ascertain by the processes already directed (IV. B., 
 1, 2), and by IV. C. examine the liquid ( a ) remain- 
 ing after the precipitate. The alkalies are soluble, 
 and need not be here regarded. 
 
134 CHEMISTRY OF POTTERY. 
 
 TO FIND THE ACIDS, ETC. 
 
 A. (1.) To the powder add test 26 ; efferves- 
 cence, with a gas inodourous, prove acid 8 present, 
 or 16 when odourous. "The aciduline solution (2 d ) 
 put into a test-tube, and insert a cork through which 
 passes a thin glass tube, twice bent at a right 
 angle (n) ; the other end place in a vessel with test 
 30, alkalinised by test 2, and closed from the 
 atmosphere ; the presence of acid 8 is proved by 
 a white precipitate, soluble in test 26. 
 
 (2.) (When the compound combines base, 22, 25 
 or 26 with its other components, employ nitric acid 
 and test 36 ; but for) any other, a dissolve in test 26 ; 
 dilute much with water ; add test 30, and a white 
 precipitate will prove acid 1 present. 6 Treat the 
 powder with test 25 ; warm ; when nitrous gas 
 evolves, and sulphur deposites, or the aciduline 
 liquid, filtered and diluted, to test 36 supplies a 
 white precipitate, a sulphuret is present ; (if of 
 mercury, while separating in nitro-muriatic acid, 
 chlorine evolves, as already described, II. D.)'. 
 
 (3.) In cool nitric acid when possible dissolve 
 some of the compound ; dilute ; add test 32 ; a white 
 curdy precipitate proves 12 present. 
 
 (4.) Some of the powder put in a leaden capsule, 
 and moisten with test 24 ; cover with waxed traced 
 glass ; corrosion proves 13 present. By glowing coals 
 determine the presence of acid 2, and of 11 by the 
 blow-pipe (as before). 
 
 (5.) When 1, 7, 11, and 16 are absent, by blow- 
 
HUMID ANALYSIS. GENEBAL PEOCESSES. 135 
 
 pipe examine for acid 6. The aciduline liquids of 
 compounds whose metallic bases precipitate by test 
 15, also their sulphurets, by heat dissipate test 14 ; 
 by test 2 neutralise ; then, as above directed, find 
 7 and 13, and 6 by the blow-pipe. 
 
 (6.) The alkaline liquids of compounds whose 
 bases precipitate by test 13 (employed also for 20 to 
 15), by heat freed from test 14, the sulphur filter out, 
 and treat for acid 6. More difficulty ensues when 
 bases 9 to 5 and metallic oxides are precipitated. 
 To enable test 15 to obtain the sulphurets, alkalinise 
 with test 2 the earths 5, 6, 7, and 8 precipitate when 
 acid 6 is present. Prove by tests the absence of acids 
 
 7 and 13, and the presence of 6 by the blow-pipe. 
 When test 34 is present in the solution, acid 6 was 
 absent, test 2 will not prove base 8, as it will 9 
 whether that was present or not, and as proved by 
 the blow-pipe. 
 
 (7.) a When in the compound are bases 9 to 5, 
 also 20 to 10, and metallic oxides which in acidu- 
 line solutions precipitate by test 15; b the powder 
 dissolve in test 26 ; the metals present by test 
 15 precipitate ; filter, by heat dissipate test 14 ; add 
 test 24 ; a precipitate is base 6 or 5 (or 7 when in- 
 soluble on adding test 31) ; filter out the precipitate 
 (and by heat volatilise test 31). c When bases 9 and 
 
 8 are absent, yet there are present others affected by 
 test 13, alkalinise the liquid by test 2 ; add test 13, 
 filter out the precipitated metals ; the liquid treat as 
 before for acid 6. d But when 9 and 8 are present, 
 digest in test 1 ; the precipitate is 19 to 15 (with a 
 spice of acid 6) ; acidulate with test 26, and add test 
 30, a precipitate is sulphate of barytes ; filter, add 
 
136 CHEMISTEY OF POTTEBY. 
 
 test 2, a precipitate is phosphate of barytes. e When 
 both 9 and 16 are present, acid 6 with them is 
 solicited by test 1. When only the latter is present, 
 to the alkaline liquid add test 13, and the precipitate 
 is base 16 ; and by the usual method ascertain that 
 acid 6 is present or not ; or, when the former alone 
 is present, add test 5 ; effervescence and a volumi- 
 nous precipitate prove that the base is 9 ; f the 
 precipitate dissolve in test 26 ; then add test 1 till 
 all the precipitate which first appears is re-dissolved ; 
 filter, add silicate of potash, and the very sluggish 
 precipitate is base 9 with acid 9 ; filter, and add 
 muriate of lime, and phosphate of lime will pre- 
 cipitate when acid 6 is present ; or, 9 liquid ( e ) 
 acidulate with test 26, alkalinise with test 2, and add 
 muriate of lime, the precipitate will be as just named. 
 (*) When both 9 and 16 are in the liquid ( e ) add test 
 13, the precipitated sulphuret of zinc filter out, and 
 heat till free from test 14 ; the liquid treat as above 
 for base 9 and acid 6. 
 
HUMID ANALYSIS. GENERAL PROCESSES. 137 
 
 VI. Mixed Compounds insoluble in Water 
 and Acids. 
 
 TO FIND THE COMPONENT ELEMENTS. 
 
 THE refractory residue of compounds already 
 subjected to the previous processes, and which are 
 indifferent to the potency of dilute muriatic or nitric 
 acid, will consist of either chloride of silver, proto- 
 chloride or sulphuret of mercury, or sulphates of 
 barytes, strontian, lime and lead. 
 
 (1.) "In a glass test-tube heat some of the 
 insoluble residue ; when it sublimes, unaltered, it is 
 only either protochloride or sulphuret of mercury 
 (the former black, the latter red, in ammonia ; and 
 globules prove the presence of some other free base or 
 metal). b The portion which does not volatilise may 
 Jbe chloride of silver, or sulphuret of lead, lime, 
 strontian or barytes. In a proper crucible this 
 portion mix with thrice its weight of carbonate of 
 soda, and fuse. When cool, soften in water, then 
 >add more water, and digest thirty minutes ; filter, 
 acidulate with test 25. By test 36 prove the pre- 
 sence of acid 1, and by test 32 find any chloride 
 of sodium present with chloride of silver. c The 
 contents of the filter may be carbonate of bases 5 to 
 7, and 22, with metallic silver when the chloride was 
 present. Fusion may form the silver into a bead 
 in the crucible, and the portion not fused may be 
 extremely comminute in the aqueous liquid. When 
 neither silver nor carbonate of lead is present in test 
 
138 CHEMISTEY OF POTTERY. 
 
 26 (or when present in test 25), digest the filter 
 and its contents, and in the latter case add test 26 ; 
 a precipitate will be base 25. ''The aciduline 
 liquid filter, add test 2 ; a white precipitate is base 22. 
 When both 25 and 22 are present add test 15 ; the 
 precipitate treat with test 2 ; filter out base 22, and 
 add test 26. e To the liquid ( c ) in a leaden capsule 
 add test 23, and allow time for base 5, or tests 28 or 
 24 for base 6 alone, or with 7, which immediately 
 precipitates ; filter it out ; the liquid alkalinise with 
 test 2, and by test 8 precipitate 7 when present. 
 These three, 5, 6, 7, discriminate as already directed, 
 1. C. 2. 
 
 (2.) By the blow-pipe ascertain the presence of 
 any metallic oxides, also of acids 6 and 11 ; or of 11 
 alone, digest the powder in test 24 in a platinum 
 crucible till separated ; then add water, and treat 
 as before directed (6). This will not dissolve bases 
 22, 7, 6, 5. 
 
 In reference to the non-metallic substances 
 Chlorine, Bromine, and Iodine, it must be under- 
 stood that when a small bead of mic. salt and 
 deutoxide of copper is treated with a small portion 
 of the powdered substance, the blow-pipe flame will 
 produce a fine blue assay for the first, a green-blue 
 for the next, and an emerald-green for the last. 
 Berzelius. Further. The powder mix with test 24 
 in a test-tube, and heat ; when there is effervescence, 
 and a glass rod moistened with test 2 on being held 
 nigh causes white vapours, the powder is a chloride ; 
 or a bromide when the gas which evolves is offensive 
 and yellow, with sulphurous acid gas also evolved ; 
 and when it is violet, also with the last gas, it is an 
 
HUMID ANALYSIS. G-ENEEAL PEOCESSES. 139 
 
 iodide. When the first is in excess test 32 causes a 
 white flocculent precipitate ; when the substance is 
 either of the others, digesting in test 25, with yellow 
 vapours and the brown solution ; or yellow-brown 
 solution and violet vapours distinguish the bromide 
 and iodide. 
 
 For Fluorine in Fluwides the powder recently 
 moistened with test 24 is put into a leaden capsule, 
 then covered with the traced glass and carefully 
 warmed, but not so much as to melt the wax ; it is 
 then left to cool, and the glass is cleaned, and when 
 exposed the traced lines exhibit where the fluorine 
 has solicited to combination the silicic acid of the 
 glass. Or, the moistened powder is laid on the glass 
 ten or fifteen minutes, and then cleaned off. For 
 Sulphur in Sulphurets to the liquid add test 26, 
 and effervescence, while the offensive gas (test 14) 
 evolves, prove the sulphuret ; and test 13 will act 
 upon it however combined. 
 
 Whoever is wishful to make discoveries in this 
 science, to add to the general stock of knowledge 
 (and I indulge a hope of this in reference to many of 
 my readers), must constantly keep in remembrance 
 that by correct and more extensive information 
 concerning subjects, by superior skill in applying 
 the resources of the science as it at present exists, 
 and by more dexterous manipulations in current 
 processes, and appropriation of others which circum- 
 stances may create, with indefatigable attention to 
 every condition of each respective combination, he 
 may reasonably expect to equal, and in some instances 
 may surpass, his predecessors and contemporaries. 
 
140 CHEMISTRY OF POTTERY. 
 
 When the quantities first employed are carefully 
 registered, let there be a constant reference to the 
 numbers in the tables assigned to the respective 
 substances, and the acquisition will be greatly faci- 
 litated of the knowledge of the precise proportion or 
 quantity of any third substance needed to be added, 
 to separate the elementary components of some other 
 substance in the menstruum, solvent, or liquid used, 
 and likewise the proportions present in the fresh 
 compound, as well as in such menstruum. 
 
 There is a possibility that occasionally, because of 
 inexpert manipulation, the results obtained by the 
 student may not be precisely as those detailed. This, 
 however, must not discourage him to cause discon- 
 tinuance of research ; but rather let it excite to 
 patient repetition of all the steps of the process, and 
 sedulous attention to ascertain how and why the 
 differences arose. Let not the steps in any instance 
 either anticipate or supersede, but constantly supply, 
 correct knowledge of particulars, to determine the 
 existence of a common type, by which facts may be 
 generalised, and to warrant general conclusions. 
 There is a possibility that while steadily pursuing one 
 analysis through all its ramifications, reasoning on 
 one, or analogy, may suggest others, whose results 
 supply such additional control over Nature's pro- 
 ductions as to render them, even although not very 
 valuable, much more interesting than those by which 
 they were suggested. 
 
HUMID ANALYSIS. 141 
 
 PARTICULAR ANALYTIC PROCESSES. 
 
 HERE I assume that the student has already 
 (as before directed) dissolved in muriatic acid, and 
 noticed the tints caused by some powder of a sub- 
 stance conjectured to be adapted for being useful in 
 the manufacture, and that he is wishful to know 
 as well the respective component elements and their 
 relative proportions. 
 
 A. (1.) With a temperature of 110 Fahrenheit 
 applied to a platinum capsule, covered with paper 
 or a Wedgwood- ware evaporating dish (for nitro- 
 muriates or chlorides), but not of glass, evaporate 
 dry the muriatic solution ; but as it becomes 
 gelatinous, carefully stir with a porcelain biscuit rod, 
 or a platinum spatula, to prevent any loss by spirting, 
 and continue until all odour of muriatic acid is 
 dissipated, else the water to be subsequently added 
 will dissolve a portion of the silica. Raise the 
 temperature, during ten minutes, to 212. When 
 completely dry, often will there be present undis- 
 solved in the water bases 8, 9, and 20 without acid. 
 
 (2.) To the dried .powder add test 26; cover 
 with a glass plate during 24 hours' repose ; add ten 
 times the bulk of pure water, boiling hot, which 
 will solicit every substance present except the silica, 
 which filter out, wash well with boiling water, and 
 save all the washings, as well as the filtered liquid ; 
 the filter dry, and calcine the contents. Verify by 
 the calc being whiter than the dried mass, not soluble 
 by digesting in test 26, which is not discoloured by 
 
142 CHEMISTRY OF POTTEKY. 
 
 it ; fused on charcoal with equal weight of soda, 
 the blow-pipe assay is a transparent colourless 
 glass ; boiled with four times its weight of carbon- 
 ate of soda, it forms a colourless transparent liquid, 
 gelatinous when cold. Any other phenomena indi- 
 cate defective analysis, and demand the repetition 
 of the first process with the hydrate of potash. 
 
 B. (1.) "The filtered liquid and the washings 
 evaporate to one-fourth of the bulk ; alkalinise with 
 test 2 (or 3 and boil fifteen minutes, when 15 or 33 
 is present ; or with test 13) ; cover close with a 
 glass plate ; the chlorides present will precipitate, 
 except those of bases 5, 6, 7, 8 (because solicited 
 by the alkali), and 15. When 20 is present, it might 
 remain in solution ; bases 16, 17, 18, and 24 mostly 
 remain solicited to combination by the test 2. 
 b Closely cover the liquid during 24 hours' repose ; 
 then filter as quickly as possible without the action 
 of the atmosphere, and wash well with boiling water, 
 to preclude formation of carbonate of lime. 
 
 (2.) a To the filtered liquid add test 15, and 
 any precipitate determine by the blow-pipe. b Add 
 test 28 ; a precipitate will be base 5 or 6, which 
 discriminate as before. c Add test 7 ; a precipitate 
 will be base 7, and when this is filtered out and 
 washed, evaporate the liquid to one half ; then d add 
 test 6, and a precipitate will be base 8. 
 
 C. (1.) To the precipitate B. I 6 add test 1 
 in a platinum capsule, and digest at 160 for thirty 
 minutes ; the test solicits to combination base 9 
 (and 10) present ; filter. 6 The liquid acidulate with 
 test 26, and to separate the bases last mentioned 
 add test 5 till alkaline ; filter out the precipitated 
 
HUMID ANALYSIS. PARTICULAR. 143 
 
 alumine, wash, dry, and ignite. c Boil ten minutes, 
 or till the odour of ammonia be almost dissipated, 
 and the liquid is milky ; then cool, during which 
 base 10 when present will precipitate as a white 
 powder, which filter out, wash well, dry, and ignite. 
 When excess of the test 5 is employed, the small 
 portion of alumine dissolved will trouble the liquid, 
 when even a long time boiled. d When bases 9 and 
 10 are obtained by ( a ), to the liquid ( 6 ) add test 5, 
 when base 12, 13, or 14 is present, and a white 
 precipitate will fall, that is thus discriminated : the 
 air renders 13 yellowish, which results from ignition 
 in 12, and is white for 14. e When there is an 
 insoluble residue, to it add test 26, and allow twelve 
 hours' repose ; whatever remains insoluble will be 
 silica, or titanium, or columbium, which discri- 
 minate by the blow-pipe, as the colour of the 
 assay, when the precipitate has been fused with mic. 
 salt, will be a white, or yellow, or brown, for 
 each respectively. 
 
 D. (1.) The residue of B. 1 a digest with test 
 24, at least one hour ; evaporate dry ; heat to dis- 
 sipate the excess of acid ; then stir into a quantity 
 of water, and filter out the sulphate of lime, dry and 
 ignite it. If sulphates of magnesia and the metals 
 be present, they are soluble, and must be obtained, 
 as already directed, or by subsequent processes. 
 
 (2.) a The dilute liquid acidulate with test 26; 
 add test 4, or 5 ; filter out and wash well the pre- 
 cipitated bases 18, 20, or 33, which discriminate 
 as usual, the excess of carbonic acid keeping soluble 
 bases 8 and 15, when present. b Or add test 2, and 
 filter out bases 15 and 20 when present, carefully 
 
144 CHEMISTKY OF POTTEKY. 
 
 stirring in the test till a little of the base 20 appears 
 at the bottom of the glass jar ; then add test 16 to 
 precipitate all the iron. c Add test 3, boil, and filter 
 out the base 15 ; or, if with 8, rf add test 13, filter out 
 base 15, which by heat free from test 14. 'Add 
 test 6 and test 2 in equivalence, and there will 
 be two precipitates of phosphate of ammonia and 
 magnesia. /r The filtered liquid heat to 200 for ten 
 minutes, and base 14 will precipitate (also when test 
 2 is added) ; filter, dry, and ignite. g The filtered 
 liquid gently boil, and add test 1 ; filter out base 8, 
 wash well, dry, and ignite. 
 
 E. (1.) a The filter and its contents (2 a above) 
 digest in test 25 ; neutralise with test 1 ; dilute the 
 liquid to ten times its bulk, and filter out the pre- 
 cipitate bases 20 and 18. 6 Evaporate the filtered 
 liquid to one-fourth ; acidulate with test 26 ; raise 
 to 160 for seventy-five minutes ; filter out base 33, 
 wash well, dry, and heat till the whole is green. 
 c The precipitates ( a ) dissolve in test 26 ; dilute to 
 ten times the bulk ; carefully add test 2 ; filter out 
 base 20, wash well, and dry. d The liquid evaporate 
 dry, heat the residue to volatilise the test 2, wash 
 well and dry the base 18. Or, e To the solution ( c ) 
 add test 2, and instantly filter ; soon does the liquid 
 appear troubled and discoloured, and in twenty-four 
 hours the base 20 is obtained. f To the contents of 
 filter (E. 1 a ) add equal weight of nitrate of potash, 
 put into a platinum crucible, cover close, and fuse. 
 The chromic acid solicits to combination the base 1 ; 
 the manganesic acid similarly solicits the portion of 
 the oxygen not appropriated by the iron ; and when 
 the calc is well mixed in pure water, during twenty- 
 
HUMID ANALYSIS. PAETICULAK. 145 
 
 four hours both bases 15 and 20 precipitate. 
 filtered liquid evaporate till the pellicle appears ; 
 then place aside on a support to crystallise. h The 
 filter and its contents dissolve in test 26, dilute to 
 ten times the bulk ; slightly alkalinise (to restore the 
 litmus paper after being affected by acetic acid) by 
 gradually adding test 2 ; filter out base 20 ; add 
 test 9 ; filter out base 15, wash well, dry, and ignite 
 to incandescence. 
 
 j F. (1.) a Weigh most carefully each product 
 (most proper as soon as it is cool after being ignited, 
 because then free from atmospheric action), and 
 determine the total sum. The consecutive processes 
 induce losses, more or fewer as the number of com- 
 ponents, from *5 to 2 per cent. ; and in this ever 
 does each component differ from the others. When- 
 ever the total sum is within 2 per cent, of the first 
 weight, the analysis may be regarded as satisfactory ; 
 but when a larger portion is absent, there is proof 
 that some alkali or volatile component (probably 
 fluorine) was proximate, but evolved without being 
 regarded. b Careless washing may cause the total 
 to exceed the primary weight, and such culpable 
 inattention is a subject of reprehension as well as 
 regret. Avoid it most sedulously. But this excess 
 may be consequent on an oxide receiving additional 
 oxygen, which, of course, must be noticed and sub- 
 tracted. Also it may be found to be owing to the 
 formation of a basic salt, while a precipitate resulted, 
 and which salt was not decomposed during the 
 calcination or heating prior to weighing. And 
 whenever substances are examined which do not 
 
146 CHEMISTRY OF POTTERY. 
 
 chemically combine agreeably to combinative 
 potencies. 
 
 G. (1.) When the presence of an alkali is sus- 
 pected, a In a porcelain retort, with a refrigerated 
 receiver, incandesce for 30 minutes a determined 
 weight of the mineral in coarse powder, and hereby 
 will be obtained the water and all volatile compo- 
 nents. When this process does not alter the weight, 
 certainly either alkali or acid is present. b A portion 
 of the mineral powder mix with six times its weight 
 of carbonate of barytes, and in a platinum crucible 
 calcine during two hours. c The calc dissolve in test 
 26 ; separate the silica by A. 2 and base 5 by test 24. 
 To the filtered liquid add test 5, filter, and wash well. 
 The liquid evaporate to a fourth ; add oxalate of 
 ammonia, and filter out base 7, dry, and by heat 
 dissipate test 2. The residue will be an acid sulphate 
 with an alkaline base, which determine by the 
 processes already mentioned. Or, 
 
 H. (1.) a The mineral powder 1 portion, and 
 powder of fluor spar 2 portions, moistened with 
 test 24, place in a leaden capsule, and heat to 100, 
 carefully avoiding the active poisonous gas which will 
 evolve, and which is fluoric acid gas combined with 
 the silica ; the excess of test 24 also is dissipated. 
 The affusion of pure water will separate the soluble 
 salts from the sulphate of lime, and readily after- 
 wards will the alkali be found in the sulphate. 
 6 When fluor spar is supposed to be present, add 
 test 23. Any residue after the solution in test 26 
 can be thus treated. To the fluoric solution add 
 test 24, evaporate dry, calcine to low red heat and 
 
HUMID ANALYSIS. PARTICULAR. 147 
 
 dissipate the test 23, especially when present with 
 base 7. Or, 
 
 I. (1.) The mineral powder 1 portion, and test 
 36, or boracic acid 6 portions, fuse during two 
 hours in a porcelain crucible. The calc dissolve in 
 test 26, dilute to twenty bulks with boiling water ; 
 evaporate dry to dissipate excess of acid. The 
 residue stir well into pure water, then filter out the 
 silica (also the boracic acid when employed). The 
 liquid evaporate to a fourth ; add test 5, and filter 
 out bases 7, 8, 9, when present ; evaporate dry, and 
 by heat dissipate test 2. The contents of the 
 capsule dissolve in test 24, dilute much, evaporate 
 and crystallise for base 1. Add test 30, and any 
 other alkalies present will precipitate ; filter, eva- 
 porate dry. In test 31 digest, to separate base 3, the 
 others precipitate, and can be filtered out. The 
 liquid should next be evaporated, and the base 3 
 be dried and ignited. 
 
 K. (LowiTz's method ', the first published.} In a 
 silver crucible put the mineral powder 1 portion 
 with 3 of pure hydrate of potash ; moisten with 
 pure water, and boil dry, add a like quantity of 
 water, and again boil dry, and the addition of water 
 must be repeated as needed. When during the 
 ebullition bubbles large and tough are formed, the 
 process is drawing to a successful termination. The 
 calc must then be well stirred into plenty of pure 
 water, and the components separated as usual. 
 
 L. (SCHRADER'S method.} The mineral powder 
 moisten with test 1 or 3 ; put into a platinum 
 crucible and calcine one hour; mix well in plenty 
 of pure water ; evaporate to a fourth ; acidulate with 
 
 L2 
 
148 CHEMISTEY OF POTTEKY. 
 
 test 26 ; again evaporate dry ; the result dissolve 
 in a soda ley at the common temperature ; again 
 acidulate with test 26 ; dilute, evaporate, filter out 
 the gelatinous precipitate, dry, and ignite the silica. 
 
 M. (DAVY'S method.) The mineral powder 1 
 portion mix with 2 portions of boracic acid, and in 
 a silver or platinum crucible, covered, calcine forty 
 minutes. Add test 25, 3 portions, and water 16 
 portions, and digest till all is in the liquid ; evaporate 
 to a fifth of the bulk ; filter out, and well wash the 
 silica, dry, and ignite. The filtered liquid with the 
 washings, evaporate to a fourth ; alkalinise with 
 test 5, and boil until precipitation ceases ; filter out, 
 and by the usual processes discriminate the contents 
 of the filter. The liquid acidulate with test 25, and 
 evaporate till all the boracic acid is precipitated ; 
 filter it out. The liquid evaporate dry, heat to 450 
 Fahrenheit, to decompose and dissipate the salts of 
 base 4, and leave those of base 1 and 2. The alumine 
 will be supplied by test 1, lime by 24, iron by 16, 
 magnesia by pure soda, and manganese by hydro- 
 sulphuret of potash. 
 
 N. (THOMSON'S method for pure Silica.) In a 
 platinum crucible liquefy equal weight of carbonates 
 of potash and soda ; carefully add the powder 
 (ground dry flint) till effervescence ceases by all the 
 carbonic acid gas being dissipated ; then cool, and in 
 test 26 dissolve the calc ; filter, evaporate dry ; add 
 test 26, digest three hours ; then dilute with twenty 
 bulks of boiling pure water ; filter, wash well, 
 evaporate dry, and ignite the silica. 
 
 O. (1.) "When a (mineral of few component 
 elements has much of base 7 present with little of 
 
HUMID ANALYSIS. PAETICULAE. 149 
 
 bases 8 and 9, boil the aqueous solution one hour, to 
 dissipate the carbonic acid ; add test 2, and filter out 
 those bases ; wash well, dry, and dissolve in acetic 
 acid ; filter out, wash, evaporate dry, and ignite 
 base 8. To the liquid add test 2, and filter out 
 base 9, which treat similarly. Or, in test 26 digest 
 the precipitate one hour ; dilute four bulks ; add 
 test 3 ; filter, evaporate dry ; dissolve in test 26 ; 
 dilute ; let repose one hour, filter out, wash, dry, 
 and ignite base 9 ; base 8 obtain as before. 
 
 (2.) When only a little of base 7 or 5 is present 
 with much of base 9 or 8, to the very dilute solution 
 add test 24 (or 7, when only base 7 is present), and 
 filter out the precipitate. When both 5 and 7 are 
 present add test 24, and evaporate to a fourth ; 
 decant the solution, and add 500 bulks of water ; 
 the base 5 as a sulphate precipitates, and must be 
 collected on the filter as usual. 
 
 (3.) "When little of base 9 is present with 
 much of base 8, to the solution raised to 180 (not 
 boiled) add carbonate of magnesia till precipitation 
 of base 9 ceases ; then while very dilute instantly 
 filter out before the sulphate of magnesia can mix 
 with the base 9. b When little of base 8 is present 
 with much of base 9, by test 2 precipitate all present, 
 and the precipitate treat with acetic acid, and filter 
 out base 8. 
 
150 CHEMISTEY OF POTTEEY. 
 
 For the Relative Quantities. (BERZELIUS'S method.} 
 
 IN this I assume that the muriatic solution is 
 freed by nitration from silica. 
 
 A. (1.) The acidulated liquid with the washings 
 pour into a glass jar sufficiently large to prevent 
 loss by effervescence, and cover with a glass capsule. 
 Gradually add test 4, or 2, and bases 9 and 2 will 
 precipitate, which filter out and discriminate ; any 
 of bases 7 and 8 present will remain in solution as 
 bicarbonates. 
 
 (2.) a The precipitate wash well, (when test 
 4 is employed, we cannot either dry or calcine it ; 
 and the weight of base 9 must be determined by 
 subtracting that of base 20, because with base 9 is 
 test 3 insolubly combined). The contents of the filter 
 remove, and the filter itself wash with test 26. 
 6 The filtered mass digest in test 1 ; base 20 pre- 
 cipitates ; filter out, wash, dry, calcine, and weigh. 
 c When base 15 is suspected, this precipitate, prior to 
 weighing, again dissolve in test 26 ; then alkalinise 
 with test 2 ; the base 20 precipitates, which treat as 
 already directed. rf The alkaline liquid acidulate 
 with test 26, which will hold in solution base 9 ; 
 add test 5 ; the precipitate (to find whether silica is 
 present or not) filter, wash with boiling water, dry, 
 calcine, and weigh. * When test 34 is used, muriate 
 of potash is formed, base 9 precipitates, and base 4 
 evolves ; but excess of this dissolves much of base 9, 
 which gives up the other only by evaporation, and 
 may induce loss in the calculation. Besides, excess 
 
HUMID ANALYSIS. PABTICULAE. 151 
 
 of test 2 may precipitate some of the base 1 with 
 base 9,. and deceive in the quantity of the component. 
 But test 5, by leaving free carbonic acid in the liquid, 
 precludes the combination of the bases 9 and 1. 
 
 (3.) The bases 7 and 8 present as bicarbonates 
 in the solution from which the bases 9 and 20 
 have been abstracted, may be obtained by different 
 processes. "The solution acidulate with test 26, 
 which will dissipate the carbonic acid, leaving 
 present in the liquid a slight excess of base 4. Add 
 oxalate of ammonia during appearance of precipitate, 
 and after many hours' repose for the separation to be 
 complete, filter out the oxalate of lime, wash, dry, 
 and calcine with the filter in a crucible covered, and 
 placed obliquely over the lamp ; a thin iron band on 
 the inferior edge interrupts the current of heated 
 air, and promotes the ingress of atmospheric air to 
 carbonate the lime ; occasionally it is moistened with 
 test 5, dried, ignited, and weighed. The lime is 
 calculated from the proportions in carbonate of lime. 
 6 In a glass matrass boil two hours the filtered 
 liquid and the washings ; add test 3 ; when the 
 precipitate has reposed twenty-four hours decant the 
 clear liquid, filter the precipitate, and well wash the 
 filter. The liquid from the filter evaporate dry ; 
 wash with boiling water, which will leave a fresh 
 portion of magnesia undissolved. Test the liquid, 
 and if not alkaline, render it so, and again evaporate 
 dry. The magnesia or the filter wash with boiling 
 water as quickly as possible, for ^ dissolves in the 
 water ; and if cold water be employed the filtering 
 is slower, and the solubility is ^ The magnesia 
 calcine, weigh, dissolve in test 26, evaporate dry ; 
 
152 CHEMISTEY OF POTTERY. 
 
 again dissolve in water slightly acidulated with the 
 test 26. There will remain an observable portion of 
 silica, always most noticed with bases 8, 15 and 16. 
 Or, 
 
 (4.) "The liquid alkalinise with test 3, evaporate 
 dry, then add plenty of pure water, which will leave 
 separable the carbonates of bases 7 and 8, which 
 filter out, wash well, moisten with test 24, and heat to 
 incandescence, and weigh. The solution has present 
 the sulphate of lime dissolved with the sulphate 
 of magnesia ; the sulphate of lime calcine, weigh, 
 deduct its weight from that of the two sulphates, 
 and thus determine the weight of the sulphate of 
 magnesia. The proportions of the two bases appear 
 from the components of the salts. Or (less correct), 
 
 (5.) The liquid treat with oxalate of ammonia, 
 filter out the lime ; add test 6 to the muriatic 
 solution of magnesia (the simple neutral salt is 
 not precipitated) ; wash, calcine, and weigh the 
 precipitate. Or (best), 
 
 (6.) With test 3 precipitate base 8, or evaporate 
 the liquid dry, and calcine the salt ; on adding 
 water the base 8 is not affected. 
 
 When base 15 is suspected, or present, add test 
 13, the precipitate filter out, dry, and dissolve in 
 test 26 ; dilute, add test 3 ; evaporate dry ; digest in 
 water ; filter, wash, dry, and calcine, and ascertain 
 that silica is absent. Or, add test 9 ; precipitate ; 
 dissolve in test 34 ; the precipitate calcine, and 
 determine the results. 
 
 Those distinct components of the respective 
 compounds, separable without decomposition into 
 the elements as flint, clay are the proximate 
 
HUMID ANALYSIS. PARTICULAR. 153 
 
 or immediate principles, whose resolution into their 
 simple components constitutes their ultimate analysis. 
 In the prosecution of this, of greater importance is 
 the formation of a habit of calculation, and a facility 
 of manipulation, than to save time by using tables, 
 sliding rules, or logarithmic scales. Let the student 
 always, at commencing any process, carefully notice 
 whatever he is likely to need, then examine the 
 phials which contain the elements, and see that every 
 article required is present, and in a proper state. 
 Whatever researches he undertakes, the grandest 
 results are utility and the application of scientific 
 principles to the several Arts. Purchase only those 
 articles of apparatus you cannot possibly make your- 
 self, nor anything new, when you can effect the 
 process with those already in store. Conducting the 
 requisite processes to form those indispensable will 
 be as well an introduction to the technicalities and 
 the application of the various implements as it will 
 induce facility of manipulation and confidence in the 
 results. The working model of the mechanic exhibits 
 the economy of power in its construction ; the pro- 
 jected model of an edifice exceeds the paper plan 
 of the architect, and both at a comparative trifling 
 expense ; and the experiments of the student, equally 
 ^is cheap as intrinsically useful, supply accurate in- 
 formation. He who thus learns to select the most 
 simple method to effect his purpose who reflects, 
 that whenever discrepancies appear in results most 
 probably they are consequent on some component 
 present in the compounds, change of temperature, 
 or other conditions not contemplated in the general 
 detail will seldom miss the high gratification he 
 
154 CHEMISTRY OF POTTERY. 
 
 anticipates. But he who purchases all articles, and 
 those in particular named re-agents, or tests, will ever 
 remain only an half-and-half student ; one degree 
 above the mere reader of systems of chemistry, but 
 many degrees below the standard of a real practical 
 chemist. 
 
 For repeated mention of the processes to obtain 
 the element silica, I shall not be censured, as the 
 singular fact of rendering it soluble in the acids is 
 one of the discoveries most contributive to accuracy 
 in analysis, and is now an indispensable condition, 
 especially in that of minerals, approximating nigher 
 to truth than was previously imagined. No mineral 
 now is regarded as ready for further manipulations 
 until completely soluble in acids ; and when the 
 acid alone is inefficient, previous fusion with an 
 alkali is adopted, employing a silver or platinum 
 crucible when the mineral is earthy, and when it is 
 metallic one of porcelain. Uncertainty results from 
 the needful repetitions of nitration and evaporation ;. 
 and when a minute portion of the substance is em- 
 ployed, or important consequences are involved in 
 the determination, there is indispensable a degree 
 of care and attention much greater than in ordinary 
 investigations. 
 
 Although so very recently have been applied to 
 the Arts of Life the agencies of Chemistry, yet, by 
 the splendid series of discoveries, man is enabled to 
 so operate on all the various forms of matter with 
 which (he is surrounded as to cause all in turn to 
 administer to his wants or his luxuries. The details 
 of the gradations of ingenuity in any important 
 Manufacture, directs to the chief and primary 
 
HUMID ANALYSIS. PARTICULAR 155 
 
 purpose an acquaintance with its scientific principles, 
 elucidatory of obsolete productions, and of the excel- 
 lence of others more recent, and suggesting the ne 
 plus ultra. 
 
 The traditional practices of Metallurgical Che- 
 mistry continue, and current knowledge thereof on 
 scientific principles is proportionately trifling, im- 
 perfect, fragmentitious, not dissimilar to isolated 
 brilliant points thinly scattered as lucid specks on an 
 extended hemisphere of darkness. Therefore every 
 research undertaken in this domain almost certainly 
 will produce some interesting facts, and lead forward 
 to some important consequences, far beyond what 
 was first contemplated. 
 
 I have not glanced at the prevalent theories of 
 the Science. Nature laughs at them, and by extra- 
 ordinary developments at her pleasure compels us 
 to acknowledge ourselves her vassals, who vainly 
 strive to subject her operations to the laws we have 
 laid down. Chemists will ere long cease to "halt 
 between two opinions," because of the natural 
 libration of human opinions now in favour of 
 Stahl, and his imponderable element common to 
 every combustible substance ; then of those of La- 
 voisier, with his ponderable element. Science seeks 
 only the fellowship of Truth ; she leads her votary 
 from the dark and secret cell into the bright sunlight 
 of philosophy, unfolds to his view, and commands 
 him to become " the servant and interpreter " of 
 the wonderful Book of Nature, of whose contents 
 EXPERIMENT only is the true index. 
 
 The domain of Nature is boundless, vast, and 
 wonderful ; but prejudice bars up the gate through 
 
156 CHEMISTRY OF POTTERY. 
 
 which alone we can enter to obtain sound knowledge. 
 He who would jpossess this must disregard the 
 timidity which shrinks from opposition to his exer- 
 tions, and despise that tyranny of opinion which 
 condemns their objects. Wisdom, like beauty, can 
 be won only by the bold ; and he who pants for 
 immortality and the fame of generations unborn a 
 desire ever the strongest stimulant to the rightly 
 ambitious he whose talents are capable of bettering 
 the condition of his fellow-men, must crush the 
 barrier of custom and opinion, must boldly soar 
 to the accomplishment of mighty purposes, must 
 resolve to leave mankind wiser than he found them, 
 and " posterity will do him justice." 
 
 If the remarks herein promulgated be founded 
 in truth, their publicity will introduce a rigorous 
 accuracy and certainty into the manufacture of 
 which it has been imagined incapable. There are 
 exhibited harmonious analogies in the general laws 
 and constitutions of related objects. The Manu- 
 facturer may apply the mathematics to his chemical 
 investigations, and like the geometrician, by cal- 
 culation, rectify the unavoidable errors of his 
 manipulations, and eliminate from the essential 
 elements of a compound those products of its 
 analysis whose quantity cannot be reduced to any 
 admissible proportion. 
 
[157] 
 
 CHAPTER II. 
 
 TEMPEKATUEE. 
 
 TEMPERATURE of a substance is its condition 
 relative to recipience and fixation of heat the 
 momenta of the motions of atoms as nuclei and their 
 orbital spaces, compared with like action on some 
 standard, or well-known substance, as the thermo- 
 meter. And our perceptions of the recipience and 
 fixation, as compared with their action on ourselves, 
 we indicate by the general correlative terms, heat 
 and cold. And the specific heat or cold is strictly 
 the precise sum of the momenta appropriated by 
 the atomic orbital spaces, needful to render different 
 substances of the like temperature. With similar 
 conditions we expect the atoms of substances respec- 
 tively to appropriate, or evolve, like temperatures ; 
 and as the momenta are accelerated, or retarded, the 
 condition will be superior, or equal, or inferior to the 
 force of cohesion, and the compound will be a gas, or 
 a fluid, or a solid. That the elementary atoms have 
 like specific heat (although we remain without 
 proofs because of either unavoidable or unnoticed 
 errors in the experiments) seems very probable from 
 the approximating results of different metals ; for 
 
158 CHEMISTEY OF POTTEKY. 
 
 instance : those of lead and nickel are '0293 and 
 1035 ; their atomic weights 26 and 7 ; then 1 : '0293 
 : : 26 : 7618 ; and 1 : 1035 : : 7 : 7245 ; & 373. 
 
 The alteration of the orbital spaces of atoms, 
 very probably is Nature's most secret manner of 
 operation, as the researches of man have ascertained 
 little with regard to the laws that govern its varia- 
 tions in this succession metals, stones, glass, wood, 
 charcoal, feathers, silk, wool, hair. 
 
 Substances are solicited in two peculiar modes : 
 one (essential to cohesion in the usual condition 
 subjected to the general state of the atmosphere), 
 their inherent combinative potencies, which cause 
 them to remain chemically the same substances by 
 the reciprocal actions of their atoms and orbital 
 spaces ; the other, the fixation of oxygen by the 
 general motions of heat involving the preceding, 
 disturbing those orbital spaces, and by either giving 
 polarity to the atoms or rendering one of their sides 
 positive and the other negative, capacitate them for 
 chemical combination with others. Substances have 
 essential inequality in the like bulk, because of which 
 the same momenta of the motions of heat differ in 
 effect, the same impulsive force produces unequal 
 velocities, in disregard of accidental circumstances, 
 as probable difference of figure of atoms, and of space 
 for obtaining the results. Hence the same substance, 
 under like conditions, in equal weights appropriate 
 -equal momenta of atomic motions or heat, while 
 qual weights of different substances vary greatly in 
 this appropriation. 
 
 The alteration or variation of the relative dis- 
 tances of the atoms of substances, because of the 
 
TEMPEBATUBE. 159 
 
 orbital spaces being more or less dilated, is the 
 property signified by the term conducting power, and 
 causes expansion, differing according to continuity, 
 density, dispersion, irradiation, and the degree in 
 which the motions are fixed and again evolved ; 
 while the capacity for heat signifies the relative 
 capability of substances in proportion to the size 
 of their atomic orbital spaces, to appropriate and fix 
 the motions of oxygen ; in this succession metals 
 have chief capacity, liquids less, because dispersed 
 by heat, and gases least, because expanded by it, and 
 in them it is exhausted. These properties constitute 
 all which are implied by the poetical correlative 
 terms Attraction and Repulsion* 
 
 * The conducting power of gold being 1-000, that of silver is 
 973, copper -898, platinum -381, iron -374, zinc -363, tin -304, 
 lead -180, porcelain -122, flint-ware -116, clay -112. Their capa- 
 city for heat is inversely as the numbers gold '5, silver -082, 
 copper '112, platinum '130, iron '145, zinc '102, tin '06, lead -04, 
 porcelain -006, flint-ware -005, clay *002. Their melting reci- 
 pience, gold 5237, silver 4717, copper 4587, platinum 23177, 
 iron 21637, zinc 700, tin 442, lead 612. Their appropriation of 
 'Oxygen, gold 1- and 2-, silver 3-5, copper 2-5 black, 12*5 red; 
 platinum 1- and 2-, iron 28'75 black, 48*12 red; zinc 32-12; 
 tin 23'5 ; lead 11*53 red, 15-384 brown ; antimony 18'6 ; man- 
 ganese 28-75 and 57'5 ; from slightly aciduline solution, or 
 water, or combustion with nitrate of potash ; alumine 47*, 
 potash 20'5, soda 34-5, barytes 10'5, lime 28', magnesia 37. 
 
 The experiments of Lavoisier and Laplace determine the ex- 
 pansibility of the several kinds of glass, which at 32 Fahrenheit are 
 1-00000000, to be in these ratios at 212 : 1-00081166, 1-00089089, 
 1-00087572, 1-00089760, 1-00091751; and by Gen. Foy at 
 1-000080787. Then, as permanent glass will thus expand, no 
 wonder that the alternations of temperature cause crazing of the 
 soft glazes which cover our wares. By Mr. Daniell's register 
 
160 CHEMISTEY OF POTTERY. 
 
 By the fixation of oxygen the orbital spaces of 
 the atoms expand, and when a certain degree of 
 temperature is attained, their reaction places the 
 atoms farther asunder, supersedes the reciprocal 
 potencies of the particles among themselves, the 
 crystalline or cohesive structure, in proportion to the 
 acceleration and momenta. These exceed in sub- 
 stances with raised temperature those in others which 
 are lower, and instantly much above those needful to 
 commence the motions. The times of evolving, and 
 the precise alterations of capacity, might assist us to 
 solve the problem of the absolute quantity present of 
 the motions ; only we are unable to determine their 
 absolute absence. 
 
 Those substances whose orbital spaces of atoms 
 so readily expand as no longer to be aggregated, 
 but by the current processes of raising the tem- 
 perature become mobile, separate, and in all 
 directions slide over each other, are called fusible, 
 and their condition is that of being metalled, melted 
 or fused ; and others not thus affected are called 
 infusible. The natural condition of substances 
 seems that of solidity from low temperature, and 
 the accidental condition fluidity from raised tem- 
 perature, when fusion precedes decomposition. 
 
 pyrometer, Wedgwood's queen's-ware has linear expansion agree- 
 ably to a fixed law; at 212, 1-000735, and at 662, 1-002995; 
 precisely the same as platinum ; but this alters when it is fused. 
 These experiments prove that the ingenuity of the philosopher- 
 artist has been successful in constructing a pyrometer, with 
 sensibility to expansion by heat, of one one-hundred-thousandth 
 part of an inch ! 
 
TEMPERATURE. 161 
 
 Substances of varied temperatures, when in con- 
 tact involved in accelerated motions by fixation of 
 oxygen, have their atomic orbital spaces expanded, 
 those most involved less so than the others, during a 
 certain time, varied with the nature of the respective 
 substances, but ultimately the effect is all have the 
 same temperature, those with greatest momenta 
 solicit those with less, and all re-act in the precise 
 proportions of their capacities for heat. 
 
 Substances indifferent to accelerated motions 
 in addition to what render their particles fluid are 
 fixed, in contradistinction to the volatile, which are 
 susceptible of such acceleration, and assume the 
 state of gas. And those not volatile per se, when 
 mixed with others which are so, in high temperatures 
 evolve, and disengaged from tralatitious additions 
 again condense in a solid form ; thus sal ammoniac 
 will carry iron up in vapour ; and because of this 
 property of substances, the intense heat of the 
 potter's oven volatilises and brings into combination 
 those particles which only for the comminution 
 would not have readily united. 
 
 COMBUSTION an example of decomposition and 
 ^composition, attended with the intermediate acces- 
 sories of light and heat is the result of the combi- 
 native potency of oxygen soliciting the hydrogen 
 evolved while the motions of heat diffuse through 
 a substance in which carbon likewise is present. 
 Current knowledge, however, only compares the heat 
 evolved with the oxygen supplied, and does not 
 determine what proportion of the heat and light 
 evolved results from the oxygen present, and from 
 the recipient body. 
 
 M 
 
162 CHEMISTRY OF POTTERY. 
 
 When the atoms of oxygen, the chief positive 
 supporter of combustion, from the state of gas with 
 accelerated orbital motion, from primary force in 
 right lines and the reaction of attendant atoms, 
 are fixed by substances, these are affected by the 
 momenta ; in some instances the bulk is reduced, 
 in others enlarged, and in others with similar 
 capacity for heat.* Heat or excitement, as flaming 
 paper, applied commences the combustion of a 
 candle for instance ; the hydrogen present, excited 
 as gas, rises in orbits too large for the space, forms a 
 vacuum, which the oxygen fills with eight times the 
 force, fixed by the recipient hydrogen in particles of 
 water or vapour, and by the carbon, the atoms not 
 consumed or electrified, in carbonic acid.f The 
 
 * Lavoisier calculated that equal fixation of oxygen results 
 from the combustion of substances : oak wood 1089, charcoal 600, 
 pit-coal 600, coke 403. Kirwan regards the potencies of charcoal, 
 pit-coal, and pine wood as 57*6, 36, and 20' 1. Fossombroni calcu- 
 lates that the combustion of wood is adequate to evaporate twice 
 its weight of water. Coke supplies heat more regular and intense 
 than coal, as 8 to 3, because during combustion all its substance 
 equalises the fixation of oxygen in the maximum without any such 
 loss of a portion of its matter, as in elastic vapour evolves from 
 coal, with a supply of only a small portion of heat. 
 
 f Carbon (in its form of Charcoal) is the residuum of vege- 
 tables, by high temperature just incandesced, and all its volatile and 
 factitious components dissipated ; thus wood is treated in closed 
 vessels, and the hydrogen or water is separated, and the volatile 
 products while burning in air combine with the oxygen and form 
 carbonic acid gas. The most pure kind is by passing through a 
 red-hot tube the vapour of alcohol, or oil of turpentine. It is 
 black, insipid, inodourous, insoluble in water, brittle, very pulve- 
 rulent ; in closed vessels not altered by heat, but a gas evolved of 
 hydrogen, carbon, oxygen and nitrogen. The most dense kinds 
 
TEMPERATURE. 163 
 
 oxygen is thus fixed, and decomposes a certain 
 portion of the air ; the fixation causes an intense local 
 heat, which escapes by propelling the atoms of air, as 
 light, concentrating the motion, as heat, at the spot. 
 Whatever absorbs the heat diminishes the light 
 and the excitement ; but the process first mentioned 
 continues while hydrogen and carbon evolve by 
 fixation of the oxygen, supplied for the purpose. 
 Such, likewise, will be the causes and effects,, 
 although there be promotion of the access of 
 oxygen and varying of the circumstances. 
 
 An incombustible substance by raised tempera- 
 ture increases in bulk, but in air alone quickly 
 returns to its primary state. Under like circum- 
 stances one combustible acquires intense ignition, 
 gradually diminishes in bulk, while a stream of heat 
 and light evolves and solicits bodies present during 
 a change of all its physical characteristics. As each 
 metal ignites with oxygen it is combustible, but 
 those which do not flame in atmospheric air are not 
 termed inflammable. The substances so termed 
 evolve heat and light exceeding the proportion to 
 which their densities might seem to lead, and 
 frequently in that of their purity and perfection. 
 
 A combustible substance is consumed, or its 
 
 with greatest potency solicit the gases ammoniacal, 90 times its 
 volume, nitrous oxide 40, carbonic oxide 35, nitrogen 7J, oxygen 
 9J, hydrogen If ; and unchanged in their properties they restore 
 them at 212. In twenty-four hours charcoal absorbs from 
 the atmosphere one-twentieth of its weight of which fifteen- 
 twentieths are water. Because of this absorbency (not yet 
 explained) it is of great utility in the Arts. 
 
 M 2 
 
164 CHEMISTRY OF POTTERY. 
 
 individuality destroyed, heat and light being evolved 
 during the change of condition, because (on Lavoisier's 
 hypothesis) 1. Combustion of a substance occurs 
 only when oxygen is present, whose quantity regu- 
 lates the intensity. Ever must be present some 
 supporter ; yet of oxygen, different proportions may 
 be present without any phenomenon of combustion, 
 as this will not ensue merely from condensed oxygen. 
 2. Combustion always consumes the oxygen ; and it 
 ensues with compound supporters, where would fail 
 a simple one alone, as oxygen, chlorine, iodine, etc., 
 as when with each other, or with nitrogen. The 
 additional proportion of oxygen which constitutes 
 some substances supporters is separated by com- 
 bustion. 3. The weight of the products of each 
 substance after combustion, with that of the 
 oxygen consumed, correspond with its weight prior 
 to combustion. 4. The oxygen combined with the 
 combustible substance can be recovered from the 
 fresh compound, and the weight regained will equal 
 that lost during combustion. 5. Every instance of 
 combustion evolves light and heat, or fire. 6. In a 
 limited volume of air only can a certain portion of a 
 combustible substance be burned. 7. The burning of 
 a substance renders the air present unfit to continue 
 combustion, or support animal life.* 
 
 * Frequently have we heard disprobative remarks on the 
 murky atmosphere of the potteries, and it becomes us to fearlessly 
 and fairly meet the supposed disadvantage. Whoever has given 
 proper attention to the matter is well convinced that by remaining 
 at rest atmospheric air deteriorates ; becomes not merely useless, 
 but deleterious ; like water, stagnant, stinks, becomes corrupted 
 
TEMPERATUKE. 165 
 
 Those simple combustibles whose cohesion is 
 easily destroyed, as by melting, or which are elastic 
 fluids, are readily inflamed ; others, because of less 
 momenta of combinative potencies, are less inflam- 
 mable than some combustible oxides, and which 
 more readily than homogeneous particles combine 
 with oxygen or easily separate. 
 
 Only can a combustible substance solicit all the 
 oxygen from products, or by combining with this 
 
 and unfit to nourish animals or vegetables. If this be admitted, 
 then we may affirm that the effect on a great scale produced by 
 gales, and tornadoes, and hurricanes, and storms is on a small 
 scale accomplished for this district by the columns of rarefied air 
 which daily ascend from the furnaces of the steam-engines and 
 the ovens of the manufactories. I will allow the corrupt state of 
 an atmosphere (were it constantly to remain) saturated with car- 
 bonaceous particles, and others brushed from the ware ; the effluvia 
 from oils and tallow heated in the application to the iron and 
 brass of the lathes and other machines in constant motion ; from 
 the turpentine and tar of the painters and gilders, and the oils of 
 the printers ; the exhalations from the animal secretions and dis- 
 charges, perspirations, fumes, and evacuations ; the respirations of 
 thousands of pairs of lungs, many of the breaths naturally not the 
 most balmy, and with increased offensiveness from last night's 
 debauch ; these all mixed, s. a. form an aerial compound, neither 
 the most grateful nor healthful, and in the compass of a very limited 
 space give a congeries of disease only existent in a manufactory 
 where the animal and artificial machinery are together in motion. 
 To preclude noxious results by properly ventilating this atmo- 
 sphere, what arrangements would the man of science propose? 
 Certainly one tantamount to that existing, although disregarded. 
 He would say, avail yourself of the agency of fire ; by some long 
 tube or funnel compel corrupted air to undergo a fiery ordeal, and 
 escape to the upper regions ; exactly that which is effected by our 
 hovels and engine chimneys ; and the whole district derives ad- 
 vantages from what the ignorant regard as a cause of complaint. 
 
166 CHEMISTRY OF POTTERY. 
 
 separate hydrogen from water, as when evolved 
 during the oxidation of zinc, or iron filings, in a very 
 dilute aciduline liquid. The absence of heat and 
 light renders the oxygen of products incapable of 
 supporting combustion ; yet when these products 
 solicit an additional proportion of oxygen, again they 
 have the peculiar property of becoming supporters. 
 
 When all the conditions promote the complete 
 combustion of the products, the flame is perfect ; 
 otherwise a portion, as smoke, escapes unburned, and 
 soot results. 
 
 Assuming, as I have at p. 35, that chemical 
 combination is a result of the different and 
 opposed potencies of the elements or substances 
 exhibited together, we only need to reflect and 
 admit, that, as each substance and element ever 
 retains peculiar permanent combinative potency, only 
 modified by the re-action of that with which it com- 
 bines ; also, that those elements or substances which 
 combine always have opposite combinative forces 
 and momentum ; also, that this remark applies to 
 oxygen, acids, and all positive substances opposed to 
 the negative hydrogen, alkalies, earths, and metals ; 
 and that the conditions of the union of these are 
 exhibited as heat, light, fire, electricity, and others 
 similar, heat and flame, heat and light, for all the 
 phenomena of combustion to be readily explicable. 
 As the extreme receptive potency can be solicited 
 by other less receptive, because to a certain degree 
 the two are relatively positive and negative, we find 
 oxygen and chlorine form permanent compounds. 
 
 By artificial means, or electricity, we appear to 
 collect the pure aciduline and alkaline principles 
 
TEMPERATUBE. 167 
 
 whose concentration, in points, supply the intense 
 atomic motion, momentum, excitement or heat of 
 their condensation ; and also light by the union of 
 those gases in the atmosphere and the substance 
 encountered their combustion or dispersion of what- 
 ever is present. The knowledge of this principle of 
 excited momenta, and its dexterous application to 
 effect useful results from the properties of substances, 
 more excitable than others, or which break, evaporate, 
 silently and gradually expand, radiate, absorb, dis- 
 perse, or again combine because of it, are essential 
 to the chemist. Only by carefully regarding the 
 endless continuity of phenomena and change in 
 the relative and reciprocal potencies by substances 
 acquired and exerted from the universal agent of 
 nature, motion, can we possibly arrive at correct 
 and beneficial conclusions. 
 
 Until the atmosphere of the oven is at 1000 
 Fahrenheit its particles retard combustion ; therefore 
 the nearer it approximates to that temperature by 
 contact with some heated substance before it per- 
 meates the oven, the more successfully will it solicit 
 and fix oxygen. The cave of the glass furnace 
 causes the atoms which pass through it to alter their 
 momenta, and the diminished motion of the atoms 
 enhances their fixation in the fire. A passage is 
 constructed for the conveyance of fuel from the open 
 space belonging to the manufactory, and beneath the 
 hearth of the oven forms a vaulted space named the 
 cave. From this the air, in a state of raised tem- 
 perature, is admitted into the furnace, there it is 
 decomposed, the oxygen is for the greater part fixed ; 
 the azote passes out of the oven above the level of the 
 
168 CHEMISTEY OF POTTERY. 
 
 men's heads, and is carried up the hovel. The doors 
 supply only the proportion of air indispensable for 
 the respiration of the workmen, and consequently 
 nearly all the advantages of the accelerated velocity 
 of draught produced by the height of the hovel are 
 appropriated by the furnace. And as every pound 
 of coal thus consumed, in order to be completely 
 saturated with oxygen for its perfect combustion, 
 must have a current of air containing thrice the 
 quantity which mere theory would assign for the 
 purpose, and must have 20 Ibs. of air, or 265*5 cubic 
 feet (as M. Clement has demonstrated), the velocity 
 needs to be artificially accelerated. Air itself is 
 remarkably sluggish, more so than any other sub- 
 stance in conveying heat ; and it is because of this 
 that our oven-men can during a short interval bear 
 without inconvenience the extremely high tem- 
 perature of the oven while drawing the seggars, 
 these last being so hot that thick rags are requisite to 
 protect the hands, and yet the body is not injuriously 
 affected. There is no reason why the potter should 
 not improve his processes whenever the advantages 
 of economy and utility are connected. As intense 
 heat in the glass furnace at a constant temperature 
 results from the adaptation of the cave, there certainly 
 is a possibility of so adapting the potter's oven as 
 to be benefited by subterraneous draughts. Some 
 smelting furnaces are supplied by red-hot air, 
 obtained in this manner : A range of iron pipes of 
 large bore, from 20 to 30 feet long, is surrounded by 
 a circular flue of brick-work, at the distance of 8 
 inches. While along this flue passes the fire of a 
 furnace to keep the pipes at a red heat, the blast 
 
TEMPEEATUEE. 169 
 
 engine propels the air through the pipes into the 
 furnace, during which the hydrogen atoms are 
 separated, and those of oxygen are fixed. 
 
 The calculations, etc., of M. Clement and 
 Desormes have induced the conclusion that the 
 temperature of the furnace for smelting iron is 
 increased 270 360 Fahrenheit by the application 
 of the hot-air blast, which increase is regarded as 
 adequate to the explanation of all the observed 
 effects. 
 
 The principle itself obtains in the construction 
 of the potter's oven. A number of small apertures, 
 or vents, whose areas are exactly equal to that of 
 each bag, are adapted to promote the equal distribu- 
 tion of the fixation of oxygen throughout the whole 
 interior of the oven itself, usually being placed 
 above the mouths that the air admitted may obtain 
 the high temperature without cooling the seggars 
 affected. 
 
 There is a great necessity for solving the pro- 
 blem What degrees of temperature must be sup- 
 plied to the respective kinds of ware, in baking 
 biscuit or glaze, to render each permanent in ordinary 
 alternations ? Hence the potter should be accom- 
 modated with a pyrometer by which he may ascertain 
 the high temperatures in his oven, and be able readily 
 and accurately to read them off on a determined 
 scale during any period, or the whole, of any baking 
 process, that he may thereby possess a greater degree 
 of certainty than at present, in reference to the 
 employment of fuel. 
 
 About a century ago Mr. Ralph Shaw, of 
 Burslem, while using mixed clays to form his 
 
170 CHEMISTRY OF POTTERY. 
 
 "patent" pottery, noticed the different tints which 
 the same body acquired by the several degrees of 
 temperature in the various parts of the oven. The 
 application of this principle by John Mitchell to 
 regulate his baking process, and thereby render his 
 wares superior to others, was one cause of Shaw's 
 action against him for alleged infringement on his 
 patent.* The extension of the principle to regulate 
 all the processes by (trial pieces, in the parlance of the 
 workmen, or what I shall call) pyrometrical beads 
 was by the brothers Thomas and John Wedgwood, at 
 a time when the party, to whom because of the name 
 all the merits of this and their other improvements 
 have been assigned by some philosophical journal- 
 ists, was not more than ten years of age. The beads 
 they introduced, and which are still employed, are 
 much similar to a small poppy head, out of which 
 has been cut the calyx. 
 
 Scarcely does any person need be told how very 
 indeterminate in regard to temperature are the 
 expressions a red, a bright red, and a white heat.f 
 Even were these three conditions most plainly and 
 
 *This action was tried at Stafford, in July, 1736, all the 
 Manufacturers bearing a portion of the expenses with Mr. 
 Mitchell, and those of that day most respectable were present 
 in court. A most intelligent and completely disinterested special 
 jury nonsuited the plaintiff; and the learned judge thus con- 
 cluded his announcement of their decision : " Go home, potters, 
 and make whatever kinds of pots you please ; only do make them." 
 
 f As indicated by Wedgwood's pyrometer, the respective tem- 
 peratures of these metals, copper at 27 melts, iron at 90 welds, 
 cast iron at 130 is in fusion, or runs among the fuel 150 ; yet- 
 to each as to all we apply the term white heat. 
 
TEMPEBATUEE. 171 
 
 obviously distinguished from each other, the terms 
 have much latitude of application, for the brightness 
 and the luminousness of incandescence increases 
 with the fixation of oxygen, through the numerous 
 gradations, which cannot be indicated by words nor 
 discriminated by the most experienced eye. To the 
 philosopher-chemist, who reasons on the difficulty of 
 perfectly describing by words the ideas of colours 
 that the differences in visual powers, and in the 
 lights by which pyrometrical beads are examined ; 
 also, that the very slight difference of many tints, as 
 well as the presence of vapours floating in the 
 interior of the oven are likely to preclude just 
 determinations the employment of such beads may 
 be liable to many and insuperable objections, and 
 especially when we take into the account the slight 
 differences of spicing of iron, which affects the 
 alumine of common clay, and the consequent varia- 
 tion of tints that will be presented by pyrometrical 
 beads of different kinds of clay baked together at the 
 same time, and others placed in different parts of the 
 oven. But the fact is indisputable, that the fireman, 
 by the tints of these beads, with great precision 
 discriminates the varied heat of different parts of the 
 oven during the baking process, either biscuit or 
 glaze, and accordingly regulates his supplies of fuel. 
 Concerning the progress of this process, often is the 
 experienced eye of the fireman able to render avail- 
 able the different appearances presented by the 
 interior of the oven, and the tints of the trials, and 
 even independent of these, not seldom will he come 
 to just conclusions when the fuel is of one kind. 
 And this on the same principle, as only those persons 
 
172 CHEMISTRY OP POTTEKY. 
 
 who are accustomed to examining objects through a 
 telescope can easily and readily avail themselves of 
 its services. 
 
 The observation, that in the highest degrees of 
 noticed temperature some particularly pure clays 
 had contracted in volume, more than one-fourth in 
 every dimension, appears to have suggested the 
 application of this principle as likely to be a more 
 accurate measure of heat, than the different tints of 
 colour. The diminution in bulk of alumine, and the 
 compounds of which it is a chief component, gradu- 
 ally and regularly by different degrees of raised 
 temperature, from its commencement at the low red 
 heat just visible in daylight, till the whole is vitrified, 
 therefore, at the highest degree sustainable by 
 crucibles and seggars, is one of those evidences 
 whose depositions need to be most attentively and 
 scrupulously investigated. 
 
 On this principle, however, is founded the ingeni- 
 ous pyrometer which Josiah Wedgwood announced 
 as his invention, but others claim as that of Thomas 
 Massey, Mr. Wedgwood's chief fireman, by whom 
 was made the beads supplied from Etruria during 
 his lifetime (one of which has been heated to 120 
 of that scale, and reduced to one half of its former 
 bulk, though it has lost only two grains in weight, 
 and one-third of its specific heat) ; but as he most 
 determinately refused to communicate to Mr. Wedg- 
 wood himself the full particulars of their composition, 
 all those sold after his death, which had not been 
 prepared prior thereto, were discovered by different 
 persons, Sir James Hall, Dr. Kennedy, Guyton, 
 Morveau, and others, to want the accuracy possessed 
 
TEMPERATUBE. 173 
 
 by the others. This is the real cause why pyrometers- 
 are no longer sold at Etruria. The statement of 
 Parkes, that clay for the supply of these beads for 
 an indefinite term had been prepared by Mr. Wedg- 
 wood, is entirely a gratuitous assertion. Whatever 
 was the modicum of chemical knowledge possessed 
 by him, the practical proofs every day before him, of 
 the chemical reaction of the reciprocal components 
 of his clays, would convince him that any such pro- 
 cedure would be an abortive attempt for the purpose. 
 
 Persons who have imitated the beads have 
 obtained results differing not only from those Mr. 
 W. assigned, but likewise from each other. The 
 pyrometer beads he sold, formed of pure alumine 
 mixed with china clay, as well as those made of the 
 latter only, which he had in the first instance sup- 
 plied to friends for their trials and remarks, differ 
 from his own, in indicating the temperature needful 
 to fuse silver as 22 on the pyrometer gage, not 28 
 as marked on the scale. He has acknowledged that 
 "he has often found differences, astonishing when 
 considered as a part of this scale, in the heats of his 
 own kilns and ovens, without being perceivable by 
 the workmen at the time, or till the ware was taken 
 out of the kiln." The difficulty of compounding a 
 clay which contracts equally by heat has long been 
 considered an almost insurmountable obstacle to the 
 employment of this pyrometer. Mr. Sivewright pro- 
 poses the substitution of small pieces of the mineral 
 agalmatolite, or Chinese figure-stone, for the beads, 
 because of its regular and equable contraction. 
 
 Convinced as I am of the utility and importance 
 of an accurate physical measure for those very high 
 
174 CHEMISTEY OF POTTERY. 
 
 degrees of temperature, and the absolute necessity for 
 this pyrometer to be based on some other principle 
 than the mentioned property of the natural aluminous 
 compounds ; also believing that by a philosophical 
 attention to the principle, and not merely the mecha- 
 nical agency of the heat, Mr. Wedgwood might 
 happily have succeeded in the attempt, some of its 
 imperfections I have mentioned, from a desire that 
 every means likely to promote its perfection should 
 be adopted. The contraction of clay is dependent 
 as much on the manner in which, as the degree to 
 which, the temperature is raised. The beads are 
 contracted by this last as much in three minutes as 
 they can be in three hours of the same degree of 
 temperature, and the higher this is the more readily 
 is the contraction effected, as far as observation goes. 
 
 Manufacturers certainly may derive one advan- 
 tage from using this pyrometer. Calcined alumine, 
 also aluminous compounds, do not undergo any 
 diminution of bulk by a subsequent application of the 
 like temperature as by any addition thereto. Hence, 
 by adapting to this gauge a fragment of any wares 
 made by other nations, or at other and distant periods 
 of time, and to a raised temperature subjecting it, in 
 company with a proper bead, till the diminution of 
 this commences, there will be supplied correct data of 
 the temperature at which such ware was baked. 
 
 Mr. W. Daniell's pyrometer is a tube of black 
 lead, or of flint ware, with a platinum bar. Long 
 prior to knowing this, I suggested to different friends, 
 manufacturers, one constructed in the following 
 manner : The composition of which seggars are 
 formed remains refractory in the highest temperature 
 
TEMPEBATURE. 175 
 
 of the ovens. Of this composition, by the squeezing- 
 box form a tube, 16 inches long, and 1 inch bore ; 
 therein place four bits of the clay, formed with a thin 
 edge, as supports, and firmly close up one end. By 
 the drawing-rod place this tube in any part of the 
 oven where it can rest supported between seggars. 
 Into this tube insert a platinum wire of one-sixteenth 
 of an inch thick, and of suitable length (perhaps 
 twenty-four inches), with one end pressed against 
 the bottom by the slight resistance of the long arm 
 of a compound lever, so combined with others that 
 the smaller end of the last of the series can move the 
 index, which should traverse an arc of six inches, 
 graduated from 62 to 160. As this bar could be 
 introduced at any period of the baking process, 
 immediately on being raised to the temperature of 
 that part of the oven in which was placed the tube, 
 not only would the degree be always truly indicated, 
 but also the time during which it continued at a 
 certain degree. 
 
 The pyrometer invented by M. Achard, of Berlin, 
 appears to me to be capable of such modification 
 as to supply the potter's firemen with a standard for 
 comparing, under any and every condition, the varied 
 degrees of the baking processes. The principle is 
 expansion and contraction of metals, and when 
 these are constant and uniform, they supply data for 
 relative measures of high temperature, which may be 
 with great advantage adopted by the Manufacturers. 
 
 Of hard felspar porcelain body, by the squeezing- 
 box draw out a true half-inch tube, eight inches 
 long ; through this pass a true rule, on which form 
 the tube into an oval ; to this tube carefully fix a 
 
176 CHEMISTEY OF POTTERY. 
 
 ball of uniform thickness, and two inches diameter* 
 Bake this ball and stem in the highest temperature 
 of the oven. Purify some bismuth, lead, and tin, 
 and of each respectively take 50, 20, and 30 parts, 
 which will fuse together, and afterwards be con- 
 stantly fluid at the temperature of 212 Fahrenheit, 
 and solid at 62. On the stem or tube mark zero ; 
 then immerse in boiling water, and pour in the fluid 
 amalgam precisely up to zero. Cool down the whole 
 to 62 Fahrenheit, and the place, as seen through the 
 semi-translucent tube, correctly mark. The interval 
 equals 150, which divide into three, and this will 
 supply the degrees for all above zero, each of which 
 will be equal to 50 Fahrenheit, and may be sub- 
 divided into 5 parts. In this must play a porcelain 
 vernier, with a platinum stem, which, as well as the 
 tube, will clearly indicate the degrees of heat. The 
 present trial-holes will need only a little variation of 
 form to admit the introduction of this pyrometer into 
 the oven at different periods of the baking process. 
 
 Agreeably to this method of calculation the 
 following table supplies the number of degrees of 
 temperature proper for baking the wares, or melting 
 the metals mentioned. Though sufficiently accurate 
 for ordinary purposes, yet like all other philosophical 
 speculations they must be received with caution, as 
 there cannot possibly be precluded discrepancies in 
 the results of different experimenters : 
 
TEMPEEATUKE. 
 
 177 
 
 Best Felspar Porcelain - - 
 
 Fahrenheit. 
 
 - 22165 
 
 Biscuit. 
 
 423 + 
 
 Glaze. 
 403 
 
 Wedgwood. 
 
 156 
 
 Champion's Ditto - - : -' 
 
 - 19214 
 
 368 + 
 
 356 
 
 135 
 
 Olrl "Rrvw"T)ittn 
 
 i 007 
 
 qo 
 
 qorj 
 
 m' 
 
 Common Canton Ditto - - 
 
 - 15950 
 
 ooo 
 
 329 + 
 
 o^u 
 320 
 
 
 120 
 
 Derby Ditto - - \> '.:.-.,. - ( 
 
 - 15637 
 
 308 + 
 
 300 
 
 112 
 
 fVioicfa T^itfo 
 
 14.797 
 
 290 + 
 
 280 
 
 105 
 
 
 
 Chemical Utensils Ditto - 
 
 - 14727 
 
 290 
 
 
 
 
 
 Stone Ware Ditto - - - 
 
 - 14337 
 
 282 + 
 
 270 
 
 102 
 
 First Worcester Ditto - 
 
 - 13297 
 
 262 
 
 280 
 
 94 
 
 Bone Earth Ditto - - - 
 
 - 12583 
 
 250 
 
 235 
 
 90 
 
 Flint Earthenware - - - 
 
 - 12257 
 
 244 
 
 230 
 
 86 
 
 Wedgwood's Queen's Ware 
 
 - 12000 
 
 240 
 
 230 
 
 86 
 
 Delft Ditto - - - , - !"'-' 
 
 - 6277 
 
 
 
 
 
 40 
 
 Enamel Colours - - - - 
 
 - 1857 
 
 38 
 
 
 
 6 
 
 Gold, for burnishing 
 
 / 1750 
 \ 5237 
 
 35 
 
 
 
 6 
 32 
 
 Cobalt ..---.- 
 
 - 17977 
 
 
 
 
 
 130 
 
 i\/r 
 
 - 21877 
 
 9HK77 
 
 
 
 
 
 160 
 ififi 
 
 
 Great misconception prevails, even among well-informed 
 persons, respecting the degrees of temperature quoted in foreign 
 journals as compared with those of our own, or Fahrenheit's, used 
 also wherever the English language prevails, while Reaumur's is 
 current in Germany, Celsius's (or the Centigrade) in France, and 
 Delisle's is now employed by many philosophical chemists, the 
 interval between the freezing and boiling points being divided by 
 them into 80, 100, and 150 F. 
 
 To render the degrees in the above table into equivalent degrees 
 of any other thermometer, any person who knows addition, sub- 
 traction, and division needs only recollect that 1 F = f B, and f 
 C ; and 6 F = -5 D ; and 130 F = 1 W. Or, centigrade into 
 Fahrenheit, multiply the number of degrees of the centigrade by 9, 
 and divide the product by 5. When the centigrade degrees are 
 below the freezing point, subtract the quotient from 32, and when 
 above thatpoint,add it to 32; the sum will be the equivalent degrees 
 on Fahrenheit. Suppose the centigrade, or French thermometer, 
 at 15 degrees below freezing, multiply 15 by 9, divide the product 
 by 5, and the quotient will be 27, which, subtracted from 32, 
 leaves 5 the equivalent number of degrees on Fahrenheit ; and 
 suppose the centigrade marks 20 above freezing, multiply 20 by 9, 
 divide the product by 5, which gives the quotient 35, and, adding 
 32, the sum will be 67 the equivalent degree in Fahrenheit to 20 
 
 N 
 
178 CHEMISTRY OF POTTERY. 
 
 in the centigrade. To convert Reaumur into Fahrenheit mul- 
 tiply the given number of degrees of Eeaumur by 9, and divide 
 by 4, and add 32, or subtract the quotient from it, as in the 
 foregoing example. 
 
 Connected with this and the following subjects is the problem, 
 What quantity of atmospheric air is needed to completely ap- 
 propriate all the heat from the fuel ? The requisite proportion 
 of air must be adequately supplied to the several particles of fuel 
 adapted for fixing and combining with the oxygen of the air. 
 Experiment proves the need of more air than what contains the 
 precise quantity of oxygen for full combustion of the fuel. M. 
 Clement's analysis of the gas discharged at the top of a chim- 
 ney, where no smoke whatever was visible, and of course the com- 
 bustion was complete, proved that about two-thirds of the oxygen 
 was not fixed. By Montgolfier's suggestions for determining the 
 effects, proportionate dimensions, and convenient arrangements of 
 parts, of furnaces, to be most useful, M. Clement demonstrates that 
 practice requires thrice the quantity of air to be in contact with 
 the fuel, of what theory would assign for full combustion. For 
 1 Ib. coal, and wood, 20 Ibs. and 10 Ibs. respectively are required 
 of air. As each cubic foot of air weighs 1-2054 ounces avoirdupois, 
 527*368 grains troy, a pound measures 13-271 cubic feet. Hence 
 we can determine the quantity of air which in a given time passes 
 through a furnace to consume a given quantity of fuel. Air is 
 78 nitrogen + 22 oxygen ; and to supply heat to dissolve 9*638 
 ice the combustion of charcoal requires 251 oxygen. The quan- 
 tity for the combustion of other fuels is estimated by the quantity 
 of ice their heat will melt, assuming that the heat evolved is pro- 
 portionate to the oxygen required for the complete combustion ; 
 and this, for 100 wood, and 100 coal, requires 83, and 166 of 
 oxygen. 
 
1179] 
 
 COAL. 
 
 THIS abundant combustible mineral, so very 
 important and indispensable an article of the 
 economy of social life in a country devoid of forests, 
 as is Great Britain, is here found in greater plenty 
 than in any other country of the earth. Indeed, 
 could we not thus supply the great demand for this 
 medium of fuel to fix oxygen and concentrate heat 
 in our homes and Manufactories, the country would 
 comparatively be uninhabitable. To the supposition 
 of its being used by the Britons, much probability 
 attaches ; and this is not a little supported by the 
 arrangement of the potter's oven, described in 
 another place ; while of its employment by the 
 Saxons there are numerous proofs. 
 
 The prevalent opinions of the philosophic world, 
 founded on the fact that the strata of Coal consist 
 essentially of carbonaceous matter in the blind coal 
 nearly pure are that the Coal Seams are series- of 
 ancient forests overthrown by unknown causes ; or 
 thick beds of very luxuriant vegetation of other 
 kinds of the family, covered and buried by marine 
 debris and deposits, then submerged by irruptions 
 of the sea, and charred by the heat evolved from 
 pressure during countless ages. And, because rocks 
 were not adapted for the growth of forests, whose 
 accumulations and falling produced beds of Coal, 
 mountainous districts do not present us with deposits 
 of Coal suitable for the purposes of the kitchen and 
 
 the manufactory. 
 
 N 2 
 
180 CHEMISTKY OF POTTEEY. 
 
 The Independent Coal Formation, or the series of 
 Coal Strata, thus designated because the beds and 
 patches and fields are without any apparent con- 
 nection with each other, is found most plentiful in 
 the floetz, or new secondary rocks, and in the upper 
 series or newest floetz. The strata have the old red 
 sandstone for a general basement, and they alternate 
 with beds of white, red, or grey sandstone, slate- 
 clay, fire-clay, common clay, limestone, ironstone 
 and greenstone. Their direction, unlike that of the 
 primary and secondary rocks, is generally almost 
 horizontal, the inclination, or dip, varying from one 
 to six in twenty-four feet, or from three to twelve 
 degrees. Each stratum preserves its own parallelism, 
 and some strata present their natural wavy arrange- 
 ment undisturbed, but others appear as having 
 experienced some alteration since their deposition. 
 They are not continuous, but, horizontally, and 
 perpendicularly, and obliquely, they frequently are 
 interrupted by dykes or chasms, slips, hitches, troubles, 
 and faults (caused seemingly by the strata drying, 
 or the sinking of the rocks beneath, or their being 
 raised upwards, by some galvanic agency), all of 
 which are filled with clay, sand, and rounded stones, 
 carried into them by water, or by rocks of other 
 formations forced into the interstices. 
 
 The coal formation consists of many far and 
 wide-extending alternations of sandstone, slate-clay, 
 and coal ; often also with beds of ironstone, hydrous 
 carbonate of iron and with modules of iron ore, but 
 seldom with limestone, greenstone, or basalt. The 
 vegetable petrifactions are mostly cryptogamous, 
 few monocotyledons and no dicotyledon, which, 
 
COAL. 181 
 
 therefore, did not exist when the layer was formed ; 
 three species are referred to palms, one to cannae, 
 one hundred and thirty to ferns, surpassing in size 
 any now known, all of the genera occurring in 
 the torrid zone, without one resembling any recent 
 European species ; fourteen to calamites (but whose 
 structure Brogniart refers to equisetums), with 
 gigantic stems, as large as trees, and none such now 
 exist in vegetation ; also, of the torrid zone produc- 
 tions are seven species of marsileacese, and sixty- 
 eight of lycopodiaceae. The animal petrifactions 
 are orthoceratites, terebratula, ammonites, and some 
 species of the genera lingula and miro. Some of the 
 mussel-shells occur quite uninjured, but they differ 
 from every known existing species. For the forma- 
 tion of this layer, containing these remarkable 
 vestiges of vegetables and fossils, regular deposits of 
 superincumbent layers would be adequate, without 
 supposing that there has been a change of the 
 inclination of the earth's axis prior to man being 
 formed to inhabit this planet. And electro-chemical 
 action on the vegetable mass may have given it the 
 appearance we now witness. 
 
 Britain has such a general distribution of Coals 
 that I need not enumerate all the localities. The 
 districts most likely to supply the fossil are those 
 favourable to forest growth, the valleys over the red 
 sandstone, or over the transition formation, covered 
 with the debris of tides, as clay, gravel, shingle, 
 shiver, etc., occasionally with shells of various species. 
 In these districts attention to the conditions of the 
 bassetings, or out-crops of the strata, will distinguish, 
 almost equally with boring, the nature, quality, 
 
182 CHEMISTRY OF POTTERY. 
 
 thickness, dip, of each stratum. Also, attention to 
 the water, as astringent and unctuous, or chalybeate 
 and depositing ochre, from having permeated the 
 strata of ironstone and coal usually in company 
 and acquired these characteristics, with also a darker 
 tinge. 
 
 The extensive Coal Districts of England are 
 from 20 to 120 miles in breadth, and 300 in length, 
 from the Tay to the Severn below Bristol. They are 
 largest in the West Riding of Yorkshire, from north 
 of Leeds and Birstall, to Retford, Nottingham, and 
 Derby ; next, of almost equal superficies, in Durham 
 and Northumberland, from Standrop to Berwick, 
 and from Brampton to Belford, according to one 
 calculation, 243 square miles, but another makes it 
 594 ; from South Shields to Castle Eden, 21 miles, 
 and 32 west, to West Auckland ; thence to Eltring- 
 ham 33, and to Shields 32. In this district, at 
 Killingworth, is the deepest mine at present worked 
 the botton is 460 yards perpendicular below the 
 surface. The South Wales Field is from Pontipool 
 to Kidwelly, and from Langhorne to near St. David's. 
 That of Lancashire is from Colne to Prescot, and 
 all the range round Manchester, taking Bolton, 
 Worsley, Clifton, Moston, Chatterton, and Oldham. 
 That of Staffordshire is from Lawton to Cheadle, 
 and from Wolverhampton to Dudley. There are 
 also patches in the counties of Cumberland, Flint, 
 Gloucester, Monmouth, Salop, Somerset and 
 Warwick. 
 
 The lowest stratum or bed of Coal in Yorkshire, 
 that from Halifax to Sheffield, lies above the mill- 
 stone grit, and the series between the grit and flag- 
 
COAL. 183 
 
 stone is from 120 to 150 yards. This bed is the 
 only one which supplies palpable proofs of suc- 
 cessive irruptions of the sea, in regular strata and 
 alternations of land and marine remains. There are 
 present plants and fresh-water shells, also marine 
 shells of the genera pecten, ammonite, orthoceratite, 
 ostrea, and scaly fish, while above and below the 
 pectens are mussel bands. The bed above the secon- 
 dary limestone is bitumenised timber, with leaves, 
 branches of shrubs, and shells lying upon it, and 
 shells in the intervening shale. In the Newcastle 
 Field the bed 2 yards thick is 150 yards from the 
 surface ; and between this and the surface are eight 
 other beds of 5 feet in the whole, the thickest being 
 
 I foot. At 33 yards lower than that first mentioned 
 is another 1 yard thick ; 50 yards lower, one of 
 39 inches ; 9 yards lower, one of 38 inches ; and 
 
 II yards lower, one of 2 yards thickness sixteen 
 beds, equal to 11 yards of coal, in 270 yards of 
 ground. The Beaumont seam is 34 inches thick, 
 at 213 fathoms from the surface. In others from 
 150 to 185. Some portions present 35 feet in 420 
 yards, 29 feet in 260 yards, and 28 feet in 156 yards. 
 In the South Staffordshire Field are 13 beds, in 
 thickness 23 yards of 120. The first occurs at 
 16 yards, 10 feet thick ; and below are 3 others of 
 30 feet, with only a few inches of coarse cannel as 
 a separator. The lowest bed, at 115 yards, is near 
 8 feet thick. Other places show beds at the depth of 
 1000 yards, and Scotland presents 24 beds in 233 
 yards. In all instances the intervening strata, from 
 4 feet to 120 feet in thickness, present us with 
 
184 CHEMISTEY OF POTTERY. 
 
 sandstone and slate clay ; occasionally with shells, 
 but always with animal and vegetable remains. 
 
 Now, when we regard Coal Beds as decayed 
 forests, which grew 1000 yards below the present 
 level of the surface, we must suppose an enlargement 
 of the globe, to that extent, at least, to have hap- 
 pened ; and for the 16 or 24 successive strata of 
 forests, to have been submerged by the sea in a 
 like manner, we must suppose an equal number of 
 revolutions of the earth's perihelion calculated to 
 occur once in 20*900 years. The period of this Coal 
 formation, according to this hypothesis, would imply 
 an age of our planet of 24 x 20*900 = 501,600 
 years. 
 
 Coal is a compound of charcoal, the soft in- 
 flammable substance called bitumen, and a small 
 portion of some earth, unconsumable by complete 
 incineration. The different proportions of these 
 distinguish the species of each kind in reference to 
 inflammability. The hydrogen being from 3 to 30 
 per cent., as proved by the kinds mined in the 
 counties north of the Trent, and those of Wales, 
 Kilkenny, and Devon ; the former burning vividly, 
 with much flame, the latter only with others, or in 
 heated masses. When ignited some varieties become 
 almost as soft as tar ; and others cake, or allow the 
 separation of the bituminous and carbonaceous parts, 
 very obvious in a common fire ; the coal swells, 
 softens, exhales a kind of bitumen, and burns 
 vividly with smoke and much flame ; afterwards 
 these appearances cease, and it burns with a bright 
 incandescence. 
 
COAL. 185 
 
 Coal is soft, frangible, causing considerable 
 waste in the mining, the fragments rectangular, 
 and almost cubical ; the specific gravity 1*265 ; the 
 colour is velvet black, with a slight intermixture of 
 grey ; the lustre sometimes resinous, or splendent, or 
 shining ; surface smooth ; principal fracture straight, 
 slaty, the plates splendent, or shining only ; in 
 caking coal the lustre is shining, and in some of 
 the others occasionally the appearances resemble 
 those of caking coal, but in others specular, or even ; 
 and easily distinguished by defective softening and 
 caking during combustion ; the cross-fracture usually 
 flat, conchoidal, and specular splendent ; and in 
 some, occasional portions with the aspect of wood 
 charcoal. 
 
 The three particular kinds of Coal are supposed 
 to be the products of different trees, or of different 
 ages of the world ; the Black, inflammable, seldom 
 presenting any traces of unaltered vegetable prin- 
 ciples, and devoid of the ligneous structure, and the 
 earthy particles, obviously essential to the Brown, 
 and found in the counties north of the Trent ; 
 the Black, uninflammable, the stone coal of Wales 
 and Kilkenny ; and the Brown, or Bovey Coal, 
 already alluded to, and evidently wood partially 
 charred, and with only little bitumen present. The 
 former kinds seem composed wholly of bitumen and 
 charcoal, in various proportions, having the mean, 
 per cent., of carbon 74*5, hydrogen 12*5, nitrogen 
 10*0, oxygen 3*0, contaminated with from 1*5 to 
 10 per cent, of earthy matter. The species with 
 much bitumen present we find very inflammable, and 
 while in combustion much heat and a bright flame 
 
186 CHEMISTEY OF POTTEEY. 
 
 are supplied ; while the species with less bitumen 
 and more carbon will supply heat with a less vivid 
 flame.* Their mining is not by any means a matter 
 of certain or great profit. There are great expenses, 
 of sinking the shaft to win them, of constructing 
 paths and railways to the pit, of steam-engines to 
 draw up the coal, and pump out the water, and yet 
 the results are precarious. However, when they are 
 once in this train, the existence of the seam, also its 
 direction and extent, in reference to any other place 
 in the vicinity, may be determined with tolerable 
 accuracy, by observing the dip and cropping out of 
 the strata in the workings. 
 Components of Coals : 
 
 Caking. Splint. Cherry. 
 
 Atoms. Atoms. Atoms. 
 
 Carbon 33 = 24- 75 28 =21 34 = 25-4 
 
 Hydrogen 11 = 1-375 14 = 1-75 34 - 4-25 
 
 Nitrogen 3 = 5*25 1 = 1-75 2 = 3'5 
 
 Oxygen 1J = 1-5 3J = 3'5 1=1 
 
 32-875 28-00 34-15 
 
 Annals of Philosophy, vol. xiv., 91, 2, 3. 
 
 * The fact is very remarkable, and to some may seem improb- 
 able, that the quantity of heat produced in the combustion of a 
 definite weight of coals is increased by mixture in the state of 
 powder with an equal weight of the incombustible substance clay, 
 moistened with water, to admit of being kneaded together, then 
 formed into cakes or lumps around a thin stick, dried well, and 
 kept in a dry place for use. The fuel in this state will supply 
 much more heat, during a longer period, than can be obtained 
 from coal alone in its crude state. The proportions adopted in 
 Wales are, Welsh coal, in powder, 1 part, clay 2 parts, mixed 
 together and with water kneaded into a hard mass ; then, formed 
 into Coal Balls, they are placed in the front of a fire-grate, where 
 they burn many hours. I first saw them at Carmarthen, at mid- 
 night of a November storm, and only after duly considering the 
 fact could I be persuaded of its utility. 
 
COAL. 187 
 
 The kind distinguished as Caking Coal (or bind- 
 ing, soldering, crozzling, etc.) is very readily inflamed, 
 and while the temperature is being raised by the 
 fixation of atoms of oxygen, the lumps break asunder 
 into small pieces ; in the degree of admitting the air 
 or oxygen to the igneous mass, is the clearness with 
 which it burns ; the temperature being raised to a 
 certain height, the separated pieces again cohere, and 
 form a solid mass, which originates its name. Because 
 of this, care is needed to manage it well ; but when, 
 in a common fire, it is regularly stirred to admit the 
 ingress of fresh air, much heat is evolved, and it burns 
 with a lively yellow flame. Of course this property 
 varies in the species. One kind is especially useful 
 for furnaces and forges, because it burns slowly, cakes 
 very hard, and affords a strong and long-continued 
 heat. Another scarcely cakes, but burns quickly, 
 and is preferred for heating rooms, because it makes 
 a brilliant and pleasing fire. Fire is red-hot coal or 
 wood ; flame is the combustion of carbon and hydro- 
 gen where united with oxygen, the particles being 
 scattered red-hot in the atomic excitement from dimi- 
 nution of volume, and the radiation of protrusion is 
 the effect called light. Hence the gas generated from 
 coals supplies so durable and beautiful aflame. When 
 part of the coal is ignited, and the other part not, the 
 latter evolves much smoke, or hydrogen and carbon, 
 which forms soot. The heat always arises from the 
 fixation of atoms of oxygen by excited hydrogen ; 
 and parting with their motion at the surface of the 
 combustible, where the hydrogen evolves, during this 
 latter condition they sustain the heat. A red heat 
 without flame indicates the hydrogen, unsolicited by 
 
188 CHEMISTRY OF POTTERY. 
 
 other volatile matter, combining with the oxygen as 
 quickly as evolved at the surface. Because of this, 
 and the less dispersion and cooling in the surrounding 
 air, coke is hotter than coal, and charcoal hotter than 
 wood. 
 
 Splint Coal (or hard, slaty cannel coal) is with 
 more difficulty than caking coal ignited, therefore is 
 not so well adapted for a small fire ; but, as when the 
 combustion has proceeded to a certain degree it 
 separates into pieces, and these soon afterwards 
 become one solid mass, it is for many purposes as 
 valuable as caking coal, and in a large quantity it 
 makes a strong and lasting fire. 
 
 Cherry Coal, so named from its beautiful red 
 glow when properly in combustion, requires care to 
 ignite it ; but it burns clearly, with much heat, and a 
 clear yellow flame during a considerable time, until 
 the whole of the coal is consumed. 
 
 Cannel Coal does not present any visible composi- 
 tion ; its colour is from dark grey to brownish black ; 
 its lustre, by which it is distinguished from pitch coal, 
 and other varieties, is only little, glistening, resinous ; 
 the fracture perfect and large conchoidal in every 
 direction ; in the grate, frequently slaty ; the frag- 
 ments very irregular, wedge or cubed shaped ; not 
 readily frangible, and does not soil the fingers ; spe- 
 cific gravity 1*272 ; the atoms are carbon 11 = 8*75, 
 hydrogen 22 = 275, nitrogen 1 = 175. It readily 
 ignites, and supplies a clear yellow flame, but not 
 much heat, without melting, and hence its use in 
 kitchens, during the winter season especially ; there is 
 a crackling noise connected with the ignition, and 
 fragments, very dangerous on every account, only are 
 
COAL. 189 
 
 prevented flying to different spots in the apartment 
 by dipping the block previously in water, and placing 
 the cross fracture next the fire ; the block separates 
 into leaves, which can be placed in any other chosen 
 direction. 
 
 Coke is the residue of coal, prepared either in 
 a close vessel, as a gas retort, or in a pile or open 
 kiln ; it is denser than charcoal, the similar product 
 of recently cut wood ; and the kind prepared in a 
 kiln has powers of heating which greatly surpass 
 those of the coke from gas retorts. 
 
 The several kinds of coal differ much in their 
 capacity to fix oxygen and supply heat ; yet to this 
 standard of relative value I cannot find that the chief 
 consumers of the fossil have paid proper attention. 
 The investigations in reference to the supply of gas 
 afforded have scarcely the slightest reference to 
 Manufacturers' use of coal. Only by combining the 
 results of heat supplied and the price can we deter- 
 mine the relative value of coals. The problem then 
 is What is the supply of heat by each kind of coal '? 
 
 To determine this we completely incinerate each 
 kind, and by ascertaining the proportion of charcoal 
 present, and the residuum of earthy ashes per cent., 
 we can correctly determine the proportion of bitumen. 
 This last is indifferent to the presence of nitrate of 
 potash, which detonates, and is decomposed by that 
 of ignited charcoal. The quantity of charcoal need- 
 ful to decompose a given weight of nitrate of potash 
 indicates the proportion of carbon present, and has 
 been determined as carbon 13*21 to nitrate of potash 
 100, in close vessels under water, and as carbon 10 
 to nitrate of potash 96, or plumbago 10 to nitrate of 
 
190 CHEMISTRY OF POTTEEY. 
 
 potash 96, in open vessels in air. The nitrate of 
 potash is put into a very large crucible, which is 
 placed in an air-furnace ; the coal is reduced to 
 powder like rape-seed ; when the alkali is incan- 
 descent, the detonation is kept up by projecting a 
 grain of coal in succession till it wholly ceases. The 
 quantity of coal required must be compared with 
 that of charcoal. Wigan cannel when incinerated 
 gives earthy ashes 312 per cent., and 66'5 grains 
 decomposed 480 of nitre, which only needed 50 of 
 charcoal; consequently 66 '5 grains of cannel are 
 composed of 50 charcoal, 2*08 earth, and the remain- 
 ing 14-42 grains must be bitumen. By this process 
 I have obtained the following results of coals in my 
 own neighbourhood : Kidsgrove, charcoal 72, earth 
 6'12, bitumen 21*88; Biddulph, charcoal 76, earth 
 7 '09, bitumen 16 '91 ; Bignall End, charcoal 72, earth 
 5 '08, bitumen 22 '92 ; Chesterton, charcoal 76, earth 
 S'O, bitumen 16'0 ; Apedale, charcoal 76, earth 7 '33, 
 bitumen 16 '67 ; Silver dale, charcoal 76, earth 7 P 5, 
 bitumen 16*5 ; Golden Hill, charcoal 77, earth 8 '5, 
 bitumen 14 '5 ; Tunstall, charcoal 78, earth 7 '5, 
 bitumen 14'5 ; Scotia, charcoal 78, earth 7*0, bitumen 
 15'0 ; Bykers, charcoal 77, earth 8 '6, bitumen 14 '4 ; 
 Hamill, charcoal 78, earth 8 '5, bitumen 13 '5 ; Shelton, 
 charcoal 77, earth 8 '4, bitumen 14 '6 ; Joiner's Square, 
 charcoal 78, earth 87, bitumen 13 '3 ; Bucknall, char- 
 coal 77, earth 87, bitumen 14'3 ; Foley, charcoal 77, 
 earth 8 '25, bitumen 1475 ; Lane End, charcoal 78, 
 earth 8 '4, bitumen 13 '6 ; Moss Field, charcoal 72. 
 earth 7 '5, bitumen 20 '5 ; Norton, charcoal 76, earth 
 S '5, bitumen 15 '5. 
 
 The annual consumption is calculated at less than 
 
COAL. 191 
 
 30 million tons ; on the average of 8 tons for each 
 iamily in England and Wales, or 20 millions ; and 
 from 6 to 10 for gas-works and the manufacturing 
 processes. The apprehension of a failure in supply 
 is a chimera. For, even did not science bid fair to 
 discover other and briefer means to generate heat, 
 yet on the average of a ton per annum for every 
 inhabitant in the United Kingdom, there is plenty for 
 some thousands of years. Bakewell calculates that 
 South Wales would alone supply all England and the 
 Principality for 2000 years as the present rate of con- 
 sumption ; and certainly it must be the resource of 
 the metropolis whenever danger or expense prevents 
 the supply from Newcastle. Forster guesses that in 
 the Welsh Coal District are 16 thousand millions of 
 tons, diminishing annually at the rate of 3 millions 
 of tons. Its surface is twenty times that of the Tyne 
 district, and its mean thickness is 93 feet ; and that 
 has a mean thickness of only 12 feet, with a superfices 
 of 837 square miles, of which 105 have been mined 
 in 300 years, and therefore the 732 miles left will 
 afford a supply for 2000 years longer. Mr. Taylor, 
 coal agent for the Duke of Northumberland, calcu- 
 lates thus : " Each square mile contains 12,390,000 
 tons ; then 732 square miles has 9,069,480,000 tons ; 
 deduct, for losses by small coal, dykes, and other 
 interruptions, one -third, or 3,023,160,000, there 
 remain 6,046,320,000 tons, which are adequate to 
 supply the present sales from Newcastle, Sunderland, 
 Hartley, Blyth, and Stockton, of 3,500,000 tons, for a 
 period of 1727 years." 
 
 In 1827 an intelligent Spaniard demonstrated 
 that the annual value of the coals raised in Great 
 
192 CHEMISTBY OF POTTERY. 
 
 Britain greatly exceeds that of the precious metals 
 raised in the New World ; likewise, that the value of 
 manual labour in quarrying the coals exceeds that of 
 the valuable metals found in the Transatlantic Conti- 
 nent. Thus, 30 million tons of coal at twelve francs 
 fifty cents per ton give 375 millions of francs ; or at 
 twenty-five francs per ton, mean cost 750 millions of 
 francs ; and this minus the first cost is 375 millions 
 for the value of the labour. Now (according to Hum- 
 boldt, Essays, New Spain), all the precious metals 
 were 217,500,000 francs, giving a difference in 
 favour of coal of 7j millions of francs. The cost of 
 carriage to the consumer, coastwise, is forty francs, 
 inland, twenty francs. The cost of silver carried 
 from Potosi to Buenos Ayres, 500 leagues, is 2 per 
 cent, (gold rather more), or about 5 millions of francs 
 for the whole. The value of the coals, payment for 
 labour, and profits, amount to 750 millions of francs, 
 and that of the gold and silver, carriage, etc., 222 \ 
 millions of francs ; the difference in favour of the 
 English coal trade being equal to 527 millions of 
 francs. 
 
COAL. 193 
 
 STEAM HEAT for the Printers Stoves. 
 
 Wherever steam-heat is introduced, the apparatus 
 must be constantly kept in order by a person de- 
 puted especially for that purpose ; and in his hands 
 it is perfectly safe, easily managed, and efficiently 
 directed to any distance within 250 yards from the 
 boiler, yet retain the heat of 212 Fahrenheit, and rise 
 above, in proportion to the high pressure secured by 
 the boiler and the pipes. 
 
 One single fire will provide steam for a very 
 large establishment ; and the steam will ascend, 
 descend, or pass along horizontally with undimi- 
 nished velocity, and without any abatement of its 
 temperature. 
 
 There is a very common assertion, that steam- 
 heat is more economical than that of smoke-flues. 
 How the comparison has been made is not known ; 
 but he must be a novice in the science of heat who 
 cannot produce nearly the same effect by the one as 
 by the other, under precisely similar conditions. In 
 either method it is easy to mismanage things in such 
 a manner that no more than half the heat will be 
 effective in warming the intended space ; and by 
 selecting cases for comparison, you may make either 
 appear the best method, as far as regards economy of 
 heat. Where a proper attention can be given steam 
 is preferable, but in other cases flues will be found 
 to answer better. Tredgold. 
 
194 CHEMISTRY OF POTTEEY. 
 
 PRINTING. 
 
 In 1832 I suggested to Mr. H. Davenport the 
 employment of a series of strong gas-pipes, inch bore, 
 arranged like a gridiron or the generator of some 
 steam-carriages, and to be hermetically sealed after 
 being filled with hot water, or with a small wooden 
 peg at one extremity, if supplied with steam. Now 
 if a part of this series be placed near a fire, or in 
 the flue of a fire-brick furnace, and surrounded with 
 ignited coke, the heat of the water may be raised to 
 any required temperature, and continued ad libitum. 
 The heat by the water appropriated from the fuel is 
 equal and constant, and can be reduced or increased 
 by merely opening the flue doors or stoking the fuel. 
 The water will be circulated equally, whether the 
 gridiron is above or below the level of the fire-place, 
 and at a temperature of 300 to 600. 
 
 Now Perkins and Bacon print bank-notes from 
 an arrangement of this kind ; and we only need to 
 get rid of the prejudices in favour of open stoves to 
 get rid of dirt and other inconveniences. At 400 
 the pipes will roast meat ; and at any part of the 
 arrangement a beef -steak will be readily dressed. 
 (Gardener's Magazine, 38, for a kind of apparatus.) 
 
[ 195 ] 
 
 CHAPTER III. 
 
 ACIDS AND ALKALIES. 
 
 ACID and ALKALI are generic correlative names 
 for two antagonist classes of substances the reverse 
 of each other. In the former the oxygen of the 
 atmosphere, mostly, is the active element, whether 
 by combinations abstracted or by positive electricity ; 
 in the latter the nitrogen of the atmosphere is the 
 active element, inverse in potency to the other, and 
 as concentrated in negative electricity, and an 
 important feature in nature results from their 
 reciprocal actions and reactions. Their peculiar 
 properties and potencies as recipient and agent in 
 one kind of combination with each other, in strict 
 accordance with their respective combinatory propor- 
 tions, render inert, neutralise, or saturate each other's 
 active potency, so that the equal and reciprocal 
 action and reaction preclude the appearance of any 
 aciduline or alkaline phenomena, because the com- 
 ponents in those respective proportions are recipro- 
 cally saturated, and form certain crystallisable 
 compounds, saline substances, or salts. 
 
 There will appear, en passant, numerous 
 
 instances of the probability that the method of 
 
 o 2 
 
196 CHEMISTEY OF POTTERY. 
 
 combination more than the properties of the com- 
 ponents will cause the result to be acid or alkali. 
 The two, more clearly than any other scientific 
 arrangement, elucidate the doctrine of Cause and 
 Effect, as mutually and reciprocally dependent, and 
 subject to the law under which the Creator's fiat first 
 gave them existence. By the word alkali primarily 
 was signified merely the caustic result of evaporating 
 the water in which had been washed certain incine 
 rated plants. 
 
 The alchemy of Davy on the alkaline oxides 
 first exhibited how the intense atomic motions con- 
 centrated by the galvanic circuit could so assist the 
 oxygen and nitrogen of the body and the air that 
 the medium might permit the metal to present us 
 with the phenomenon of a pure alkali, and that on 
 changing the medium union with oxygen fits it for 
 again enduring the atmosphere, as potash. In the 
 pure potash the oxygen and nitrogen were disturbed, 
 the oxygen was dispersed, and the reaction of the 
 nitrogen placed the metal, as pure alkali, at the 
 negative pole. Indeed, careful consideration of 
 the phenomena demonstrates that they all are a 
 mechanical restoration of a disturbance of the 
 oxygen, hydrogen, or nitrogen, or their correlative 
 motion, the peculiar potency of each, through certain 
 recipients, which by being the medium of precise 
 equivalents of positive and negative, may be in 
 condition altered, partially or wholly. 
 
 Acidity and Alkalinity, in some of their con- 
 ditions, seem to be Nature's active principles, whose 
 effects are measured by the relations of two certain 
 atomic motions. Positive and negative electricities 
 
ACIDS AND ALKALIES. 197 
 
 may be regarded as pure oxygen or acidity, and 
 .pure hydrogen or nitrogen, or alkalinity. Hence 
 the peculiar potencies of their contrast and action, 
 completely distinct from those of either when 
 operating alone. 
 
 We need a certain guide to illustrate the truly 
 mysterious subject what difference in atoms renders 
 them aciduline or alkaline, and neutral. We know 
 that only when in motion gas or fluid have atoms as 
 these powers, of which they are destitute when fixed. 
 Now, gas being the result of atoms moving in cir- 
 cular or orbital directions can this be the true or 
 real cause ? the varied inclinations of the planes of 
 the orbits to surfaces in reference to each other, 
 the acid atoms may operate vertically, the alkali 
 atoms horizontally, and the diagonal or intermediate 
 angle be the neutral state, the results being governed 
 by bulk, momenta, and combinative potency. 
 
 ACIDS are those peculiar substances which par- 
 ticularly affect others dissimilar, whose reactions 
 cause certain results ; thus, with the alkaline, earthy, 
 and metallic oxides, in water as a medium, they 
 form neutral salts. Much the greater number are : 
 1. Sour to the palate ; the plus of oxygen affecting 
 the sense of taste ; yet that this is a result of equiva- 
 lence of acid and alkali seems probable from the fact 
 that it is pleasingly harmonious for the aciduline 
 power to be destroyed by suitable combination with 
 an alkali. 2. They corrode substances ; and this 
 well-known effect of the acid on the substance 
 suggests many applications of acids to accomplish 
 a great variety of purposes and changes, in different 
 
198 CHEMISTRY OF POTTERY. 
 
 departments of the Arts of Life. 3. They are soluble 
 in water to an extent not precisely determined. 
 4. They change to a red tint the purple and blue 
 juices of vegetables, and to a brown those which 
 were green. 
 
 The ALKALIES in all probability have the prin- 
 ciple the same, but the medium of its operation 
 causes a real difference in its phenomena. They are 
 of three classes, those in which oxygen is combined 
 with a metallic base Potash, Soda, Lithia ; that 
 without oxygen Ammonia ; and those with oxygen, 
 hydrogen, and carbon the vegetable alkalies, sup- 
 posed to be of like number to the vegetable acids. 
 Their potency is determined by the quantity of acid 
 rendered inert; thus, sulphuric acid 7 Ibs., at 1/8485 
 specific gravity, exactly neutralises 10 Ibs. of car- 
 bonate of potash, 66 of potash, 75 of carbonate of 
 soda, and 44 pure soda. Besides forming salts by 
 neutralising acids, the alkalies, potash, soda, lithia 
 and ammonia, 1. Change vegetable colours, the reds 
 to a purple, many purples to a green, and yellows 
 to a red-brown ; the red of an acidulated purple 
 is destroyed, and the purple restored by an alkali. 
 2. This potency on vegetable tints (like continued 
 solubility) remains after the alkali is saturated with 
 carbonic acid, distinguishing alkalies from alkaline 
 earths, as carbonates inefficient. 3. Applied to the 
 palate the savour is urinous and acrid, caustic to the 
 tongue and skin. 4. They forcefully, as solvents 
 or corrosives, combine with organic compounds or 
 animal substances, and with animal fat and vege- 
 table oils they form neutral soap. 5. They combine 
 
ACIDS AND ALKALIES. 199 
 
 with water in every proportion, and almost so with 
 alcohol. 6. At bright incandescence they decom- 
 pose and are volatilised. 
 
 The neutralised atmospheric air in which sub- 
 stances exist by weight is composed of oxygen 1 and 
 nitrogen 3*5, to which standard there seems indis- 
 pensable necessity for these substances to be accom- 
 modated. With each of the aciduline bases oxygen 
 is present to such a degree of equivalence for 
 neutralisation that any additional proportion above 
 those needful to produce its stable condition and 
 ensure its sustentation of the atmosphere renders 
 the substance an acid ; as the gas by hydrogen (sup- 
 posed by some persons to be constantly a component 
 of), nitrogen, the intractable carbon, refractory 
 silicum, boron, the volatile substances sulphur, phos- 
 phorus, selenium, arsenic, antimony and tellurium ; 
 and chromium, with the six new laboratory produc- 
 tions, vanadium, molybdenum, tungsten, tantalum, 
 titanium and osmium. With each of the alkaline 
 bases nitrogen is present with such equivalence that 
 in the ordinary state of the atmosphere an additional 
 dose of oxygen causes neutralisation, and the result is 
 an oxide or earth in which acidity is not perceptible 
 (as those from which the galvanic circuit exploded 
 or protruded the oxygen, potassium, sodium, lithium, 
 barium, strontium, calcium, and magnesium ; also 
 the six others, which, oxidated, form white earths, 
 aluminum, glucinum, yttrium, zirconium, thorium, 
 cerium). Acids solely oxidate iron, nickel, cobalt 
 and manganese. The other fourteen metals preserve 
 the metallic state, yet are by heat or combustion 
 
200 CHEMISTRY OF POTTERY. 
 
 oxidated in various degrees. All of these bases 
 having present in their metalline state more alkali 
 than the atmosphere, or neutral proportion of 3*5 
 to 1, the addition of small proportions of oxygen 
 form oxides, without acidity. We may regard 
 carbon as neutral, yet by additional oxygen con- 
 verted into carbonic acid ; and potassium as an 
 alkali, by oxygen reduced to the standard of 3 '5 
 to 1 in potash. Gay Lussac regards the alkalinity 
 of metallic oxides as resulting from the two distinct 
 sources the alkaline nature of the metal, and the 
 acidity of the oxygen, under modified proportions 
 and combinative potency. 
 
 To form the fixed alkali an additional dose of 
 oxygen is necessary to balance that in the atmo- 
 sphere, and capacitate the alkali to exist without 
 further neutralisation. Suppose the base a com- 
 pound of nitrogen and carbon, or silica (as, if 
 potassium were nitrogen 2, carbon 2, or silica 2 ; 
 i.e., 2 x 3-5 == 7 + 2 x 3 == 6 == 13, or 2 x 3'5 =7 
 4-2x8 = 16 = 23; also, if barium, a more potent 
 alkali, were nitrogen 4, carbon 2, or nitrogen 4, 
 silica 2; i.e., 4 x 3*5 -14 + 6 - 20; or 14 4- 16 
 = 30 ; to which, if hydrogen be not constantly a 
 component of nitrogen, one must be added for the 
 metal's combustion and fixation of oxygen), then 
 the conversion of the metal into an alkali is the 
 addition of one proportion of oxygen, and the con- 
 version of the alkali into metal is the abstraction of 
 the oxygen, and the substitution for it of one pro- 
 portion of hydrogen, as the means of its combustibility 
 as a metal. 
 
ACIDS AND ALKALIES. 201 
 
 Of real Acid, in this succession, Sulphuric, Nitric, jMuriatic, and 
 Carbonic, the Alkalies and Earths 100 parts appropriate : Potash 
 82-48, 84-96, 56-30, 105-00; Soda 127-68, 135-71, 73-41, 
 66-80; Lithia, with each variable; Ammonia 383-80, 247'82, 
 171-00, and variable; Barytes 50', 56-, 31-80, 28-2; Strontia 
 72-41, 85-56, 46-, 43-20; Lime 143-, 179-50, 84-49, 81-81; 
 Magnesia 172-64, 210, 111-35, 200; Alumine 150*90, variable 
 with both, 335-00. 
 
 The above acids above 100 parts appropriate of the Alkalies 
 and Earths in this succession : Potash, Soda, Lithia, Ammonia, 
 Barytes, Strontia, Lime, Magnesia, Alumine ; Sulphuric 121-48, 
 78-32, 67-90, 26-05, 200-, 138-, 70', 57-92,65; Nitric 117'70, 
 73-03, 65-48, 40-35, 178-12, 116-86, 55-70, 47'64, 53-80; 
 Muriatic 177'60, 136-20, 128-74, 58-48, 314-46, 216-21, 118-30, 
 898- 947-30; Carbonic 95-10, 149-60, 118-36, variable, 354-50, 
 :231-, 122-, 50, 64. 
 
 The Combinative Tendencies, active and receptive of Acids, 
 Alkalies, and Earths : 
 
 Sulphuric. Nitric. Muriatic. Acetic. Carbonic. 
 
 Potash 62 58 32 26 9 
 
 Soda 58 50 28 25 8 
 
 Lithia 56 48 26 23 7 
 
 Ammonia 46 38 14 20 4 
 
 Barytes 65 62 36 29 14 
 
 Strontia 62 60 34 28 13 
 
 Lime 54 44 20 19 12 
 
 Magnesia 50 40 16 17 6 
 
 Alumine 40 36 10 15 2 
 
202 CHEMISTRY OF POTTERY. 
 
 BORACIC ACID. 
 
 THIS rare production of the mineral king- 
 dom is in silvery white, thin, irregular, hexagonal 
 scales, brittle between the teeth, but not ductile, 
 specific gravity 1/479, to the touch greasy like 
 spermaceti, savour first sour, next bitter and cool, 
 afterwards pleasantly sweet, odour none till treated 
 with sulphuric acid, when one like musk evolves, 
 almost insoluble in water at 212, but soluble in 
 alcohol, and the solution burns with a beautiful 
 green flame ; not affected by the solar rays ; it 
 effervesces with alkaline carbonates ; vegetable blues 
 it renders red, yet it gives this tint to turmeric also. 
 It has been recently discovered, to the quantity of 
 9 per cent., free, in several lakes of thermal waters 
 near Monte Rotondo, Berchiais, and Castello Nuovo, 
 in Tuscany, also in large quantities in a solid state ;. 
 and it has been so reduced in price thereby as to 
 allow of its use to combine with soda, and form 
 Borate of Soda, or Borax. Its crystals are acid 
 57 + 43 water, in two proportions, one for crystal- 
 lisation, the other as a base to the acid. 
 
 The honour of discovering bwon, the base of 
 boracic acid, is divided among Davy, Gay Lussac, 
 and Th^nard. The first, on subjecting it to the 
 potency of the galvanic circuit, obtained a small 
 portion of a chocolate-coloured substance, solid, 
 without savour or odour, specific gravity 1*025, and 
 atomic weight 1. The others mixed boracic acid with 
 an equal quantity of potassium, and at a low red heat- 
 obtained boron and sub-borate of potash. 
 
ACIDS AND ALKALIES. 203 
 
 Process. For a small experiment a glass tube will answer, 
 but on a larger scale one of copper is preferable : Well dry both 
 the components, potassium and boracic acid; then intimately 
 mix them, put the mixture into the tube, loosely cork up the 
 ends, and expose the whole to the fire till incandescent ; then 
 withdraw the tube, and when cool, with hot pure water wash 
 out the whole of the calc, and let the liquid repose twenty-four 
 hours ; filter the decanted liquid, wash the filter till the wash- 
 ings are not affected by syrup of violets. The boron dry in a 
 capsule, and put into a phial, which keep well closed. 
 
 When the temperature is very gradually raised 
 the water of crystallisation is dissipated, and the 
 boracic acid melts a short time previous to incan- 
 descence, which state it attains, and loses half its 
 remaining proportion of water, and then fuses freely 
 into a glass with specific gravity 1*803, permanent 
 in the highest heat of the potter's oven, where the 
 remainder of the water is dissipated ; hence its great 
 utility as a component of the best glazes. This 
 glass, after exposure to the atmosphere, is a shade 
 opaque, without soliciting moisture from it ; yet its 
 properties continue, for after being dissolved in 
 boiling water it can be recrystallised for use in the 
 artificial gems or pastes. But when the rise of 
 temperature is great and sudden, because the water 
 of crystallisation cannot gradually evolve, the assay 
 intumesces or bubbles up, and the acid sublimes and 
 is called calcined Boracic Acid. Because of this 
 peculiarity, and when other components of the glaze 
 cause a sudden rise, there are occasional defects in 
 the glazes. When mixed with soot at a high tem- 
 perature is formed a pitchy compound, soluble in 
 water but subliming by calcination, and scarcely is 
 
204 CHEMISTEY OF POTTERY. 
 
 the acid, mixed with fine charcoal powder, vitrefiable 
 by a high temperature. 
 
 Boracic Acid with greater momentum solicits 
 Lime to combination than it manifests towards any 
 other base ; yet it sluggishly forms BORATE OF LIME 
 by mixing its solution with lime-water, or by lime- 
 water separating the soluble alkaline borates. In 
 each borate of lime precipitates, insipid, white, and 
 scarcely soluble in water. BORATES OF BARYTES and 
 MAGNESIA, except being insoluble, are in other re- 
 spects similar. In a direct way Borate of Alumine 
 is with difficulty formed. At a very high tem- 
 perature boracic acid combines with silica, and 
 forms the solid vitreous permanent Borate of Silica, 
 insipid, insoluble, changeless by the atmosphere ; 
 and with the momenta of accelerated atomic motions 
 at high temperatures soliciting to combination 
 borates previously saturated with other bases. Hence 
 also the beautiful transparency of glazes in which 
 this predominates. The Borate of Potash has been 
 seldom employed, either in its neutral state or with 
 excess of base ; yet in the Arts it is as useful as the 
 next article. 
 
 BORATE OF SODA, BORAX. This compound, 
 found native in different parts of the East Indies and 
 South America, has long been an article of com- 
 merce, as Tincal, and considerable quantities are 
 consumed weekly for glazes, although considerable 
 risk attaches because of its impure state and varying 
 alkalinity. During a considerable period the method 
 of purifying Tincal into Borax was known and 
 practised by only the Dutch and Venetians, but 
 
ACIDS AND ALKALIES. 205 
 
 the processes have been ascertained, published and 
 improved. M. ChaptaFs process is operose yet very 
 useful. He carefully boils during a given time 
 [16 hours] a solution of tincal, which after being 
 filtered is evaporated, left to crystallise, and the 
 resulting crystals are subjected to a like process. 
 The crystals obtained by the latter are white and 
 transparent hexagonal prisms surmounted with 
 pyramids ; the savour is styptic, and the fracture 
 greasy. It is soluble in 6 parts of water, at 212 ; 
 and when this solution is distilled in a retort, part of 
 the boracic acid rises during the process and crys- 
 tallises in the receiver (an excellent form for the 
 pure test). It is very soluble in alcohol, also in 
 alcohol and water, for paper dipped into a mixture 
 of the latter burns with a green flame. By raised 
 temperature borax intumesces, boils, loses its water 
 of crystallisation, and fuses into a white opaque porous 
 powder, called Calcined Borax, and a higher tem- 
 perature renders it a yellow, transparent, efflorescent 
 Glass of Borax. 
 
 Process. A new Borax. In pure water, at 212 Fahrenheit, 
 dissolve common borax till the specific gravity is 1*246, then 
 lower the temperature. At 174 crystals begin to form, and con- 
 tinue forming till the temperature is at 133; then decant the 
 liquid. With the same definite proportions of acid and base, and 
 only half of the water in common borax present, the specific 
 gravity is 1'815 (common borax 1'74) It is not brittle by the 
 sudden application of 30 or 40 degrees of raised temperature, but 
 it is harder, swells less, flows easier, and therefore probably is 
 more useful than common borax. 
 
 Analysis of Borax. Of the sample brought 
 weigh 78 grains ; also, of sulphuric acid (specific 
 
206 CHEMISTRY OF POTTERY. 
 
 gravity 1'800, or 70 per cent, real acid) 14 grains; 
 this acid carefully add to the salt, and the solution 
 will acquire the tint of onion-peel (not a wine-red), 
 and the shade of the tint will instantly show the 
 quantity employed, subtracting the last grain ; and 
 when the whole of the acid is needed, the article 
 is genuine (supposing only soda and boracic acid 
 present). 
 
 Boracic acid has been observed in the craters 
 of certain volcanoes, particularly in that of Vulcano, 
 one of the Lipari Islands ; it was first observed as a 
 deposit from the thermal springs of Sasso, in Sienna, 
 Italy. It exists also in plenty in the Lagoni, in 
 Tuscany. 
 
 Considerable quantities are imported to be 
 converted into borax for the potter's use in glazes. 
 
 The kind of Vulcano is in small scales, trans- 
 lucent, having a pearly lustre and a white colour, 
 except when tinged yellow by accidental presence 
 of sulphur. 
 
 It is very light, and the scales adhere to the 
 fingers ; slightly saline savour, soluble in water, by 
 which is separable all sulphur, from 5 to 20 per cent. 
 At first it tinges green the flame of a candle, until 
 the water of crystallisation is completely dissipated, 
 when that tinge disappears. Stromeyer regards it 
 as then pure, but with its water of crystallisation. 
 
ACIDS AND ALKALIES. 207 
 
 MURIATIC ACID. 
 
 MURIATIC (or Hydrochloric) ACID, the spirit of 
 salt of former times, is sour in savour, pungent 
 .and peculiar in odour (which so irritates the epi- 
 glottis as to prevent its entry, else death would 
 ensue), corrosive to the palate and tongue, with a 
 specific gravity 1 *384. Raised temperature changes 
 its bulk, not its properties. 
 
 Process. Take a tubulated glass retort, and to the beak lute 
 a long glass tube, with the free end recurved to dip into the 
 mercury of a pneumatic trough. Into the retort put 8 parts of 
 decrepitated sea- salt ; into the tube put chloride of calcium (or 
 ignited muriate of lime), and let the bent end dip into mercury, 
 when convenient. In the tubulure fix a syphon-funnel ground 
 close, and through this introduce at intervals 5 parts of concen- 
 trated sulphuric acid. The gas which evolves in contact with 
 air fprms a hazy cloud, with beautiful prismatic tints in a strong 
 light, but invisible, yet having all the mechanical properties of 
 air, in a glass jar over mercury. This gas is muriatic acid a 
 compound of chlorine and nitrogen. 
 
 The muriatic acid of commerce is gas 3, water 
 6, and is thus prepared : 
 
 Process. A tubulated retort of glass or of iron with a pottery 
 head and a well-ground stopper is connected with a receiver con- 
 taining a certain quantity of pure water. Into the retort put a 
 mixture of decrepitated salt 44 parts, and pure water 19 parts, 
 then mix sulphuric acid 28 and water 9, which add to the mixture 
 in the retort, and immediately close the tubulure. Without 
 artificially raising the temperature, the sulphuric acid solicits to 
 
208 CHEMISTRY OF POTTERY. 
 
 combination the alkali, from which the muriatic acid gas evolves 
 and is condensed in the water in the receiver to double its weight, 
 yet with increase of bulk of only one half. This product is 
 muriatic acid, of a straw colour whenever there is impurity in 
 the salt or an accidental spice of iron. The dry residuum is 
 persulphate. 
 
 When a burning taper is introduced into chlorine, it is quickly 
 consumed with a dull red flame, which throws off a dense black 
 smoke : phosphorus spontaneously ignites in it, and burns with 
 a pale-white flame, and several of the metals, in a finely-divided 
 state, or in thin leaves, inflame ; and in this way tin, copper, and 
 zinc exhibit a beautiful appearance. Chlorine, mixed with the 
 vapour of water, as it is usually obtained, assumes the liquid form 
 at a temperature of 40 ; and when surrounded with snow or 
 pounded ice, concretes into a solid of a yellowish colour, which 
 is deposited upon the sides of the receiver, like the effects of frost 
 upon the surface of windows. If the gas be artificially dried by 
 passing it over substances which abstract vapour, as a salt known 
 by the name of muriate of lime, the most intense artificial cold 
 produces no effect upon it. Strong compression, equal to four 
 atmospheres, will, however, reduce it to the liquid form. It has 
 no acid properties : it is not sour, and it does not change the blue 
 colour of vegetables to red ; but it destroys all animal and vege- 
 table colours, and is a most important agent in the art of bleach- 
 ing. This, however, it can only effect when water is present. 
 
ACIDS AND ALKALIES. 209 
 
 NITRIC ACID. 
 
 NITRIC ACID is without colour, has little odour, 
 harsh savour, and corrosive potency on organic sub- 
 stances, rendering yellow those in which nitrogen is 
 present, with specific gravity 1*51, in which concen- 
 trated state it abstracts moisture from the atmosphere, 
 and is yellow only when nitrous acid is present. Its 
 components are hydrogen 1, nitrogen 1, oxygen 3, 
 or 0-25 + 3-5 + 12 = 1575. Its great utility in the 
 Arts results from the facility with which metals, tin, 
 copper, and mercury in particular, solicit oxygen to 
 combination, and thereby become soluble. When 
 nitric acid 52 parts are mixed with pure water 
 48 parts, the bulk is only 96*65 ; and the previous 
 temperature of 60 is raised to 140 ; it boils at 248, 
 and freezes at - 50. 
 
 Process. Eetorts of very thick pottery, or cast-iron, with 
 earthen tubulated heads, are properly connected with a range of 
 receivers, in which is pure water, in quantity proportioned to the 
 strength to which the gas must be condensed, by refrigeration with 
 cold water or ice, and all the joints are carefully closed. For the 
 strongest nitric acid, put into the retort very pure nitrate of potash 
 60 parts and concentrated sulphuric acid 40 parts ; instantly stop 
 closely the tubulure with the recurved glass tube. Slowly raise 
 the temperature, during about sixty hours. First there evolves a 
 red fuming vapour, whose tint gradually softens to a pale, or even 
 colourless gas when the nitric is very pure and all the materials 
 clean ; afterwards the red and fuming vapours re-appear, and con- 
 tinue till the process is concluded ; the whole product has a bright 
 marigold tint, and is in quantity equal to two-thirds the weight of 
 the nitre. The receiver is emptied and replaced, and through a 
 funnel of small bore cautiously is introduced a very fine stream of 
 
 P 
 
210 CHEMISTRY OF POTTERY. 
 
 pure water 20 parts ; the distillation is resumed, and a weaker acid 
 obtained, which is usually kept separate. 
 
 AQUA FORTIS, a weaker kind for common pur- 
 poses, is sometimes sophisticated with sulphuric and 
 muriatic acids, or one of these. When there is 
 reason to suspect the Article supplied by the dealer, 
 test 30 will by a white precipitate detect the former, 
 and test 32 by milkiness the latter acid. To separate 
 these add each test till the precipitate ceases ; then 
 decant the liquid, and in an apparatus well-fitted 
 together by grinding, and closely secured by Indian- 
 rubber caps over the joints, again distil all of the 
 former, and about Jths of the latter liquid. 
 
ACIDS AND ALKALIES. 211 
 
 SULPHURIC ACID. 
 
 SULPHURIC ACID is without colour or odour, but 
 is very sour to the palate, and extremely caustic and 
 corrosive to the skin, with combinative potency on 
 litmus so very great that a single drop will render 
 red an immense quantity of water, through which 
 one drop of litmus tincture has been diffused. Its 
 components are hydrogen 1, sulphur 1, oxygen 2, or 
 0*25 x 4 x 8 = 12-25, specific gravity 1*845 ; so 
 seemingly oily, as to be in common parlance named 
 oil of vitriol ; so attractive of water, that when 
 exposed to the air one day it imbibes a third of its 
 weight, and six times its weight in a year. With 
 such Momentum does it combine with water, that a 
 rise of temperature from 60 to 320 is consequent. 
 It boils at 620, distils without change of properties, 
 and freezes at 15 It is the result of combustion of 
 sulphur, maintained by oxygen present, in a close 
 vessel to prevent the escape of volatile vapours, with 
 water in which they can be condensed. 
 
 A chamber is formed, all of whose sides are 
 lined with lead, and adapted to be readily closed from 
 the atmosphere. A furnace is fixed to supply heat, 
 and the flue passes beneath the floor of the chamber. 
 Near one side, and a foot above the bottom of the 
 chamber, is fixed a strong iron plate over the fur- 
 nace ; this has its outer edges raised as a rim. On 
 this iron plate is placed a small chamber to contain 
 the combustible materials, 8 parts of sulphur and 1 
 part of nitrate of potash. The bottom of the chamber 
 
212 CHEMISTET OF POTTERY. 
 
 is covered with a shallow stratum of pure water, and 
 a small valve in the roof of the chamber is the only 
 aperture for the air. The temperature is gently 
 raised till the materials are ignited, which soon 
 occurs ; from the nitre oxygen evolves, the vapours 
 from the sulphur are thereby acidified, and the water 
 is by them solicited to combination. Care is taken 
 always to adapt the quantity of the materials to the 
 oxygen of the air present, and to be supplied by the 
 nitrate of potash. When the combustion ceases, the 
 resulting sulphate of potash is withdrawn, and another 
 supply of sulphur and nitre introduced, adapted to 
 the condition of the chamber. Thus are the pro- 
 ducts formed and condensed in the water until other 
 combustions do not render it more aciduline, which 
 is when the liquid is about 1*390 specific gravity ; it 
 is afterwards drawn of by stop-taps and concentrated 
 by distillation, first in a large pan of lead, and 
 afterwards in a glass retort placed in a sand-bath ; 
 or, most economically of fuel and time, in proper- 
 sized alembics of platinum, placed within pots of 
 cast-iron. 
 
 Process. Pure Sulphuric Acid for Analysis. Add to the 
 acid an equal weight of pure water, and leave the whole to repose 
 24 hours; into a retort carefully annealed previously, and of 
 capacity for four times the quantity of liquid, place a few frag- 
 ments of cullet, and on this decant the clear liquid. Place the 
 retort over a charcoal fire just ignited, and by a very long adopter 
 connect it with a receiver, refrigerated in a vessel of cold water ; 
 gradually and carefully raise the temperature, and the acid will 
 regularly flow over, and must be kept securely stoppered from all 
 foreign matters. 
 
ACIDS AND ALKALIES. 213 
 
 Judicious management obtains 2000 parts of 
 concentrated sulphuric acid from a suitable supply of 
 sulphur to 100 parts of nitrate of potash. After 
 the combustion of the sulphur, the nitrogen having 
 evolved, the potash is become sulphate and bi-sul- 
 phate, with little diminution of the 39J parts of 
 oxygen first present, not one-thirtieth of that now 
 present in the liquid. This causes the inquiry : 
 Whence then are the more than 1000 parts of oxygen 
 obtained ? Clement and Desormes and Sir H. Davy 
 have supplied the following theories of their origin : 
 
 During the combustion the- sulphurous acid so- 
 licits a portion of oxygen from the nitrate of potash, 
 and forms sulphuric acid, whose combination with 
 the potash causes a little nitrous and nitric acids 
 to evolve in vapours which the sulphurous acid de- 
 composes, and the result is deutoxide of nitrogen, 
 or nitrous gas, a little denser than atmospheric air. 
 This gas, by the raised temperature of the chamber, 
 expands, ascends to the roof, and might escape by 
 the valve essential to the supply of air for acidifi- 
 cation, but its contact with the oxygen of the atmo- 
 sphere produces the ponderous aeriform nitrous acid 
 vapour, and every three parts of it is solicited by 
 four parts of the sulphurous acid flame, and sulphuric 
 acid results ; then, resuming the form of nitrous gas, 
 again it reascends, solicits a fresh supply of oxygen, 
 is as before precipitated, its oxygen appropriated by 
 the burning sulphur, and thus the alternate meta- 
 morphosis of a small quantity of nitrous gas into 
 oxide and acid supplies aciduline potency to the 
 vapours of a large quantity of sulphur. 
 
214 CHEMISTRY OF POTTEEY. 
 
 This excellent theory is modified thus by 
 Davy : Water must be present for deutoxide of 
 nitrogen to convert sulphurous gas into sulphuric 
 acid ; and a small proportion of water, 4 parts of 
 sulphurous acid gas, and 3 parts of nitrous gas, 
 condensed into a crystalline solid, instantly separates 
 in much water, and forms oil of vitriol ; deutoxide of 
 nitrogen evolves, and becomes nitrous gas by contact 
 with the air. The process continues, according to 
 the same principle of combination and decomposition, 
 till the water is strongly aciduline. 
 
ACIDS AND ALKALIES. 215 
 
 POTASH. 
 
 POTASH, in the state of hydrate, is brittle, white, 
 with odour like that perceived when slaking lime, 
 very acrid savour, caustic, and so corrosive as imme- 
 diately to destroy the animal or vegetable fibre to 
 which it is applied. Like negative electricity it 
 renders of a green tint vegetable blues, and the 
 purple infusions of cabbage and violets, that of 
 turmeric to a bright brown, and the red aciduline 
 infusion of litmus to purple ; it dissolves resins, 
 converts fixed oils and fat into soap, and without 
 effervescence neutralises acids. It is the well-known 
 alkali obtained by lixiviation of the ashes from the 
 incineration of vegetables, fumitory, fern, wormwood, 
 potato-tops, etc., cut before the seed time ; and being 
 erroneously supposed peculiar to the vegetable king- 
 dom, was named the Vegetable alkali (in contradis- 
 tinction to Soda, which was named the Mineral 
 alkali). The ashes are washed in twelve times their 
 weight of boiling water, or till the water is insipid ; 
 the solution is carefully decanted into iron shallow 
 vessels and evaporated dry, and the Potash as a 
 dark-coloured salt remains, certainly mixed with 
 some other substances, but in a condition to exhibit 
 many of its characteristics as the potash of commerce. 
 Incandescence in a reverberatory furnace separates 
 many of its impurities and forms it into pearlash, of 
 limited potency, because of the presence of carbonic 
 acid. 
 
 The supply obtained per cent, is, from worm- 
 wood 74, fumitory 36, sun-flower stalks 34, Indian 
 
216 CHEMISTRY OF POTTERY. 
 
 corn stalks 20, vine branches 16, beech, elm, fir, etc., 
 10 to 12. It is asserted by some writers that were 
 these vegetables grown near the strand, or on soil 
 manured with sea-salt, soda, not potash, would be the 
 resulting alkali, probably by varying the manner in 
 which the nitrogen solicits the others to combina- 
 tion. The early Gauls and Germans formed soap of 
 beech ashes and tallow, and the konia of the Greeks 
 was a potash ley. 
 
 The hydrate of potash is so well known to have 
 its component principles so loosely combined, as to 
 admit of its being employed as a most delicate test 
 and medium of determining the presence of acid or 
 alkali. When put into a solution of common salt and 
 water, it combines with the muriatic acid, and the 
 soda remains free, but suspended in the liquid. 
 
 Process. In 4 parts of water dissolve one part of pearl-ashes ; 
 then on 1 part of fresh-burned lime sprinkle a little cold water, 
 and when it has fallen into a fine powder, diffuse all of it in 
 plenty of water. Mix the two liquids, and in a clean iron kettle 
 keep at 212, well stirred, about 1 hour, then through a filter of 
 calico pass the fluid into a silver evaporator, and dissipate the 
 water till the residuum will, when cold, be of the consistence of 
 honey. Next put this into a phial, and add alcohol until all is in 
 solution ; then raise the temperature to 180, and stop close for 
 24 hours, during which the liquid will separate into two portions, 
 the upper being pure potash, dissolved in alcohol. This portion 
 carefully decant into a silver alembic with a glass head, and 
 distil over the spirit (or, decant into a silver basin), and evapo- 
 rate properly for crystallisation (which will take place though 
 alcohol may be present) on cooling ; and then pour into a crucible, 
 by high heat fuse it, pour it on a silver dish, and when at 63 
 Fahrenheit break it, and preserve in very close phials. 
 
 [This process will answer also for hydrate of soda.] 
 
 POTASSIUM. In 1807 Davy placed some slightly- 
 moistened pure potash on a platinum plate connected 
 
ACIDS AND ALKALIES. 217 
 
 with the negative pole of a powerful galvanic circuit ; 
 then bringing a platinum wire from the positive pole 
 to the upper surface, gradually the potash decom- 
 posed, oxygen gas was solicited by the positive pole, 
 while at the opposite, in contact with the platinum 
 plate, appeared globules of a white metal resembling 
 mercury ; which, exposed to the air, very rapidly 
 solicited oxygen and became encrusted with potash, 
 which continued to absorb moisture and form a 
 solution of potash. The metalline element in oxygen 
 gas, at a temperature that would vapourise it, exhibits 
 a white brilliant flame and intense heat, so com- 
 binative with other substances as to supply an idea 
 of the alchemist's alkahest, or universal solvent. 
 
 By the like process SODIUM was obtained, and 
 decomposition effected of Lithia, Lime, Barytes, and 
 Strontia ; whose bases, amalgamated with mercury, 
 showed them as metallic oxides. 
 
 Here arises an important inquiry : Whence 
 originates this general alkaline result of the evapo- 
 rated ley of incinerated wood and vegetables ? 
 
 The doctrine of the schools is, that nitrogen is 
 either extremely sluggish, or completely indifferent, 
 to combination in combustion. We find oxygen 
 present in calcined metals, and nitrogen, or alkali, 
 present in the results of incinerated wood, etc. 
 Then, either the rather uncommon opinion of a few 
 is correct, that nitrogen, or alkali, is a component of 
 all vegetation ; or, during the incineration, while the 
 hydrogen fixes the oxygen, the carbon and smoke fix 
 nitrogen and generate the alkali. We need more 
 information on this subject than at present seems 
 even to have been conjectured. 
 
 CARBONATE OF POTASH from the atmosphere so 
 
218 CHEMISTRY OF POTTERY. 
 
 rapidly solicits moisture as soon to become liquid 
 (therefore termed deliquescent], and only is this water 
 again dissipated at 280. It has a milder savour and 
 a weaker action on woollen fabrics than the hydrate, 
 yet by it similarly are vegetable blues rendered 
 green. In a silver crucible at a high temperature it 
 fuses, and is volatilised without its carbonic acid 
 being separated. 
 
 To determine whether the carbonate of potash 
 is adulterated : In a certain quantity of water, by 
 measure, try what quantity will dissolve ; this will 
 detect the sulphate of potash which is sluggishly 
 soluble. To detect common salt use sulphuric acid 
 at 1*141, of which 355 will saturate 100 carbonate of 
 potash. 
 
 Process. (1.) In water dissolve 100 grains, and gradually add 
 the test till neutralised ; the quantity of acid used proves that of 
 real carbonate affected, because as 355 : 100 : : the weight of the 
 test used : to the number required. 
 
 (2.) To estimate the carbonic acid present in the alkali. 
 Into a Florence flask put 4 ounces of water, by measure, and 100 
 grains of the alkali. Fill a phial with dilute sulphuric acid, and 
 place both flask and phial in the same scale, which exactly equi- 
 poise by weights in the other scale ; then gradually pour the acid 
 into the flask until no more effervescence ensues. The weights 
 will preponderate, and the number of grains needed in the flask 
 scale to restore the equilibrium will be the precise weight of the 
 carbonic acid evolved. 
 
 (3.) Carbonate of Potash (for Tests). At a low red heat, 
 calcine bicarbonate, and all the water, with half the carbonic 
 acid, will be dissipated. 
 
 It is proper, in glaze-making, to take into the 
 account the greater volatility of potash than of soda, 
 and of both when water is present, and likewise of 
 boracic acid. 
 
ACIDS AND ALKALIES. 219 
 
 SODA. 
 
 SODA, in the state of hydrate, has a grey colour, 
 and is hot, acrid, and bitter to the palate, to the 
 quantity of 75 per cent, soluble in water, never like 
 potash deliquescing into an oily-looking liquid, but 
 by a portion of its water of crystallisation evolving, 
 becoming in air a soft efflorescent substance, by 
 soliciting the carbonic acid to combination as a 
 carbonate. It possesses, in common with potash, 
 all the alkaline (or anti-acid) potencies ; it similarly 
 changes vegetable blue and purple tints to green ; 
 but it is weaker than potash in combinative potency 
 with the metals and the earths, needing a very 
 high temperature to combine with the latter, and 
 that continued some time with silica forms very 
 perfect glass. It is the nitron and nitrum of the 
 ancients, the natron of the Hebrews, and the fossil or 
 mineral alkali of the 17th and 18th centuries, because 
 it was supposed to be a peculiar product of the 
 mineral kingdom. This error is now corrected. It 
 is known to be obtained in a manner similar to that 
 adopted for potash lixiviating the ashes of in- 
 cinerated marine vegetables, or those located on the 
 sea-shore, which alone supply it in this form ; and, 
 as these plants fail to afford such results when they 
 have been transplanted to inland situations, but 
 supply potash, the opinion seems warranted that the 
 soda of these plants is derived from the muriate of 
 soda, by the roots appropriated during vegetation on 
 the sea-shore. There is also considerable difference 
 
220 CHEMISTKY OF POTTEKY. 
 
 in the quantity and quality of the products of plants 
 of the same species from different countries. That it 
 exists subterraneously in vast impure deposits in 
 the bowels of the earth is demonstrated by the 
 fact of its being usually, and to a large quantity, 
 abstracted by active springs and running waters. 
 Hence in some countries, as Hungary and Egypt, 
 combined with carbonic acid it is obtained in 
 immense quantities ; and from the Trona lake alone 
 upwards of 100 tons come into the market. 
 
 In its caustic state, whether supplied by the de- 
 composing process detailed under the substance 
 Potash (p. 216) certainly a very ready one ; or, by 
 the combustion of excess of sodium in air only just 
 sufficient for its conversion into this alkali, and 
 with a high degree of temperature, the fracture is 
 vitreous, the receptive potency sluggish, and a 
 continued incandescence precedes its fusion. On 
 adding a little water to the alkali violent action 
 and reaction ensues, the alkali assumes a crystalline 
 appearance, and becomes more fusible and volatile. 
 When its solution is treated with tartaric acid, or 
 muriate of platinum, no precipitate ensues as when 
 applied to solution of potash. 
 
 SODIUM requires a greater galvanic power than 
 potash to decompose the pure hydrate. It has a 
 beautiful lustre, like silver, fuses at 200 Fahrenheit, 
 and at a state of incandescence vapourises. At the 
 ordinary temperature of the atmosphere it scarcely 
 affects dry air or oxygen ; it has less potency than 
 potassium in most substances, yet more slowly 
 tarnishes, and like it is best preserved under naphtha. 
 When heated and immersed in either oxygen or 
 
ACIDS AND ALKALIES. 221 
 
 chlorine it forms a most brilliant flame ; and, cast 
 on water, it causes violent effervescence, without 
 flame, swims on the surface, with much agitation 
 diminishes gradually, and forms a solution of soda. 
 When burned in excess of oxygen, there is formed 
 the peroxide of sodium, of a fine orange colour, very 
 fusible, deflagrating with combustibles at a high 
 temperature, and, when treated with water, its 
 oxygen evolves, and there is formed, as before, a 
 solution of soda. As far as they have been inves- 
 tigated, there seems much similarity in the action 
 and reaction of the different combustible substances 
 and gases on the peroxides of sodium and potassium. 
 And when we recollect that of all the acidifiable 
 combustibles sulphur most potently solicits sodium, 
 I think, we need not be surprised at the glaze being 
 rendered yellow whenever sulphurous vapours enter 
 the seggars during the baking process. 
 
 Carbonate of Soda, the impure soda of commerce, 
 obtained from Spain and the Levant under the 
 Spanish name Barilla (that of the plant whence 
 the Spaniards obtain it), is extensively used in this 
 manufacture for the glazes of best earthenware and 
 common porcelain, and also in those of the finest 
 glass (as well as for soap, and for the processes of 
 bleaching), etc., because of the facilities supplied by 
 the very comminute state of ground flint, or silica in 
 Lynn sand, for chemical processes to aid its com- 
 binative potency by a high degree of temperature. A 
 great proportion of that employed by potters and 
 by other Manufacturers to supersede potash when- 
 ever an alkali is needful, is now fabricated from 
 common salt (as subsequently described), and 
 
"222 CHEMISTRY OF POTTERY. 
 
 afforded at one-third of the expense formerly 
 attached. A most remarkable fact is, that it has 
 the like components as prussic acid, only with much 
 difference in the respective proportions. 
 
 Processes. (1.) By sulphuric acid convert common salt into 
 sulphate of soda (after separating whatever portions are present 
 of sulphates of lime and magnesia), which by ignition with saw- 
 dust or pit-coal slack convert into sulphuret of sodium ; either 
 add lime or dissipate the sulphur by roasting and the sodium will 
 become carbonate of soda. In open vessels let the lixivium rest , and 
 after two successive crystallisations the results will be very fine. 
 
 (2.) To a solution of sulphate of soda add pyro-acetic acid and 
 lime ; during two hours keep up the ebullition, and the sulphuric 
 acid of the liquid will enter into combination with the lime, while 
 the separated soda is solicited to combination by the acetic acid. 
 When the liquid is cool, filter, then evaporate dry, calcine the 
 residuum, redissolve in pure water, evaporate till a pellicle forms 
 on the surface, and then leave to repose, and the crystals of 
 carbonate of soda will be formed. 
 
 (3.) Hodsoris Patent. Well-burned lime 3 cwt., slake with 
 strong brine, and sprinkle until the salt accumulates on the sur- 
 face ; spread in thin layers, and when dry calcine to a reverbera- 
 tory furnace. To this calc add 3 cwt. of salt, or salt-rock, and 
 again calcine ; next add 2 cwt. of sulphate of lime, and 2 cwt. of 
 the supersulphate of potash, then stir in frequently two spadefuls 
 of coke, small coal, or charcoal (every quarter of an hour at 
 most), until are used 2 cwt. of charcoal, or 3 cwt. coke, or 4 cwt. 
 small coal, then continue to raise the temperature during four 
 hours ; next draw out the mass, and when cold, break the calc 
 into lumps for use. 
 
 Of the imported impure sodas of commerce the 
 Spanish is best. It is dark bluish coloured (as in the 
 best French), ponderous, sonorous, dry to the touch, 
 and externally marked with small cavities, free from 
 offensive odour, very salt savour, and by exposure to 
 the air undergoes a saponaceous efflorescence. The 
 
ACIDS AND ALKALIES. 223 
 
 worst kinds have a fetid odour, and are white, 
 soft and deliquescent. The respective values of the 
 several kinds have not been determined by careful 
 analysis, and the ease with which the article can be 
 adulterated almost precludes the hope of any advan- 
 tage from it. The relative excellence of the article 
 depends on the absence, or the proportion present, of 
 vegetable alkali, muriate of soda, sulphate of potash, 
 also lime, magnesia, alumine, silica and even iron. 
 Many plants when incinerated, and the ashes 
 levigated and evaporated, supply carbonate of soda, 
 which varies in purity with the plant itself. Those 
 of Spain and Africa supply 25 to 40 per cent., 
 Smyrna 40, East India and Cape 45 ; whereas the 
 Blanquette 8, and of some other European districts, 
 from 8 to 12 only. At Alicante when the plants 
 approach to a dry state they are incinerated, and this 
 is continued with just sufficient ardency for semi- 
 fusion, causing the result, of a superior quality, to 
 concrete in cellular masses. The KELP supplied from 
 the Orkneys, in quantity of more than 3000 tons 
 annually, is the impure produce of the fusi family, 
 which supplies only 3 per cent, of alkali. The 
 British Barilla is from the salicornia Europcea, which 
 supplies 2 per cent. 
 
 In pp. 59, 61, of vol. IX. Scheerer's Journal, are the two 
 annexed processes : 
 
 Phosphate of Soda. In sulphuric acid digest calcined bones 
 three hours to obtain the excess of lime ; the phosphate of lime 
 dissolve in nitric acid ; add equal weight of sulphate of soda, and 
 distil off the nitric acid ; add great plenty of pure water, filter 
 out the sulphate of lime, evaporate the liquid, and crystallise in 
 the usual manner. Funcke. 
 
 Sulphate of Soda. Add water while forming a paste of 8 parts 
 
224 CHEMISTBY OF POTTEEY. 
 
 of boiled plaster of Paris, 5 of Ball clay, and 5 of common salt ; 
 this paste incandesce six hours, pulverise the calc, mix in plenty 
 of pure water, strain through a flannel bag, or strong filter, 
 evaporate, and as usual crystallise.* 
 
 Carefully add sulphuric acid to a solution of carbonate of 
 soda ; during brisk effervescence carbonic acid gas evolves, and 
 by discontinuing the dropping in of the acid at the instant when 
 the effervescence ceases, the liquid, if examined, will be found 
 warm and devoid of aciduline or alkaline properties ; neither 
 sour, acrid, hot, or corrosive ; not affecting vegetable blue 
 colours, but a compound whose two components have neutralised 
 each other's potency or momentum. Yet the compound has 
 peculiar qualities ; it is slightly bitter, saline, and cooling ; much 
 employed in a crystalline form, as Glauber's salt ; the liquid is- 
 evaporated to a certain specific gravity, then left to repose, and 
 while the liquid continues at the ordinary temperature of the 
 atmosphere, the compound atoms arrange themselves in regular 
 figures. 
 
 Common salt, intended for the glazing of coarse 
 pottery, should be free from muriate and sulphate 
 of magnesia and sulphate of lime, as each has its 
 peculiar yet deleterious effect on the ware. The salt 
 melts in a red heat, and at a white heat it evaporates 
 
 *In the Operative Chemist, p. 264, Mr. Gray gives a hint, 
 which, as I regard it to be valuable, in reference to filtering,. 
 I have amplified, and for the benefit of colour-makers especially, 
 I have particularly described it : 
 
 Take one of the conical water-closet pans, in the clay state, 
 and fit to it a grid pierced with half-inch holes, slanting towards, 
 all up to the flange ; adapt to this vessel a strong funnel to bed 
 to the flange ; fix these in a firm support over the vessel which 
 must receive the liquid. Inside the cullender place a coarse 
 linen-cloth, previously wet with pure water, and over this lay a 
 damp sheet of filtering paper. Into this vessel then gently pour 
 the liquid to be filtered, and neither loss nor danger will result, 
 if ordinary care be employed. 
 
ACIDS AND ALKALIES. 225 
 
 in a white smoke, yet without undergoing decom- 
 position. 
 
 The employment of it in the dipping-tub, to 
 increase the specific gravity of the fluid, and intended 
 to keep the lead in suspension, is a very questionable 
 practice, even if the volatilisation of the muriatic 
 acid by baking was not injurious to the glaze. 
 
 On the subject of hydrates there is a difference 
 of opinion. In those whose proportion of water has 
 been accurately determined, the hypothesis of Lavoi- 
 sier has been supported by the oxygen in the oxide 
 proving to be exactly equal in quantity to that in the 
 water. Yet there is a possibility of the existence of 
 sub-hydrates with only half the proportion of water 
 present ; also super-hydrates, with twice or more 
 times this quantity. Who will affirm that the crys- 
 tallised forms of potash, soda, barytes, and strontia 
 are not super-hydrates ? Berzelius no despicable 
 authority regards that of barytes as barytes 
 1 + 9 water. 
 
 Because at the heat which melts plate-glass 
 sodium becomes fixed, its oxide, soda, is a very 
 useful component of good glazes, causing the others 
 to readily flow during the baking, without streak 
 or bubble, and yet remain equally durable and 
 permanent when cold. 
 
 Q 
 
226 CHEMISTBY OF POTTEKY. 
 
 LITHIA. 
 
 LITHIA has scarcely been known as a hydrate, 
 and is in fact the alkali of stone. Like potash and 
 soda it has a white colour, and vegetable blues and 
 purples it renders green ; the savour is acrid, like 
 that of potash, but the caustic effect on the tongue 
 is less corrosive ; in the air it continues dry, and 
 abstracts not moisture, like potash, but carbonic acid, 
 and becomes opaque or efflorescent. Its solubility 
 in cold water, as a carbonate, is to potash and soda 
 as 3 is to 10 p. and 7 s. ; the watery solution effer- 
 vesces with acids, separates the solutions of salts 
 of ammonia, metals, and alumine from magnesia ; is 
 scarcely soluble in alcohol, but this being added to 
 the watery solution, after repose of several hours, 
 precipitation of carbonate of lithia ensues ; likewise 
 when a solution of carbonate of soda is mixed with 
 that of lithia. It becomes caustic, like potash and 
 soda, by lime being presented to appropriate the 
 carbonic acid. Its nitrates and muriates are deli- 
 quescent, and it appropriates more water for satura- 
 tion than potash or soda. It is not precipitated by 
 the alcoholic chloride of platinum. When in a silver 
 crucible closely covered, at a red heat it becomes 
 transparent by fusion ; and after being at a white 
 heat during an hour, the bulk is found the same, but 
 the alkali is affected by the carbonic acid of the air. 
 If a platinum crucible be employed, the alkali power- 
 fully solicits the metal to combination. Its great 
 combinative potency with oxygen has prevented a 
 full investigation of the metallic base. The propor- 
 tions with which they combine are 1 to 1, and the 
 atomic weight is 1*25. 
 
ACIDS AND ALKALIES. 227 
 
 Process. Into a silver covered crucible put the mixture of 
 1 part pulverised petalite or spodumene, or white felspar, and 
 nitrate of barytes 4 parts ; in excess of muriatic acid digest two 
 hours to dissolve the mass, then filter out the silica, and wash 
 the filter well ; add test 24 to appropriate all the barytes and 
 displace the muriatic acid ; again filter out the barytes, and wash 
 the filter, and evaporate dry the filtered liquid; the residuum 
 again dissolve in water, filter, and alkalinise with test 3 to pre- 
 cipitate the alumine, which filter out ; wash the filter, and again 
 evaporate dry, and raise to a low red heat ; again dissolve in water ; 
 any sulphate of lime present is insoluble, sulphate of lithia is 
 soluble ; add barytes water to appropriate the sulphuric acid, 
 evaporate the water, and the residuum is lithia, or add acetate of 
 barytes, filter, evaporate dry, and calcine for carbonate of lithia. 
 
 CALCULATION OF CHEMICAL SEPARATIONS. 
 
 A substance composed of known proportions of 
 two elements a the quantity of one component 
 united with b that of the other is placed in contact 
 with another substance which solicits one of these 
 elements to combination ; B the quantity of the 
 solicited element combining with A, that of the 
 agent. (The quantities regard the same unit of 
 volume or weight.) 
 
 Often is it needful for a salt, with a of acid 
 united to b of base, to be separated by a stronger 
 acid to form a fresh salt. And whether the separa- 
 tions affect simple or binary compounds we have to 
 determine as nigh as possible the water probably 
 present, and then take for the connective of the new 
 and the old compounds either the acid or the base. 
 
 Problem I. How much strong acid will separate 
 the quantity P of the proposed salt ? The formula 
 is : b A P -T- B (a + b) = the quantity of acid needed ; 
 and the fresh salt will weigh P b (A + B) -f- B (a + b). 
 
 Q 2 
 
228 CHEMISTEY OF POTTEEY. 
 
 Problem II. How much of the proposed salt 
 must be employed to appropriate the quantity P of 
 the strong acid ? The formula is : B P (a 4- b) -r A 
 b ; and the fresh salt will weigh ( A + B) P -*- A. 
 
 They are practically applied to decomposing 
 common salt by sulphuric acid for muriatic acid, 
 also sulphate of soda, thus : Dry chloride of sodium 
 is 9 chlorine and 6 sodium, and sulphate of soda is 
 6 soda + 4 sulphur + 8 oxygen ; the water present 
 is 56 per cent., and the sulphuric acid has 20 per 
 cent. To determine the quantity of sulphuric acid 
 required to solicit to combination the soda present 
 in 25 Ibs. of common salt : a = 186*38 muriatic acid ; 
 b = 100 soda ; A = 100 sulphuric acid ; B = 78*187 
 soda ; P = 25 common salt ; and we get, 
 
 14572-40 
 
 = 17*15 Ibs. dry sulphuric acid ; to which add 
 one-fourth = 4*28 Ibs. for water present, and the 
 required quantity is 21*47 Ibs. And the resulting 
 weight of sulphate of soda, by the same data and the 
 second formula, %^iW- = liS = 30*5 Ibs. sulphate 
 of soda ; to which add 39 Ibs. water as present in the 
 crystals, and we get 69*5 Ibs. 
 
 Again. We may wish to know precisely the 
 quantity of dry common salt separable by 25*5 Ibs. of 
 strong sulphuric acid, containing 20 Ibs. of dry acid. 
 
 The first formula of the second question in 
 numbers gives 78 ' 187 1 ^ 1 X 00 186 ' 38 = f^ == 29*14 of common 
 salt. The same data, for the second formula, in 
 proper numbers will show the resulting weight of dry 
 sulphate of soda, namely m ' l f * = 35*64 Ibs., to which 
 add the water proper, 45*36 Ibs. ; for as 44 dry 
 sulphate is to 56 water in crystallised sulphate, 
 so is45*36 ; and 35*64 + 45*36 35*64 to = 81 Ibs. 
 
[ 229 ] 
 
 CHAPTER IV. 
 
 THE EAETHS. 
 
 THIS class includes those mineral substances 
 which compose the crust of our globe. In a pure 
 state they are incombustible, without savour, or 
 odour, or colour, or potency to change the blue 
 or red tints of vegetables, or their juices. 
 
 The strata and debris which form the surface of 
 our globe present earthy substances with seeming 
 countless variety ; but the rays the lamp of chemistry 
 sheds on them surprise us with the fact that all we 
 tread beneath our feet whether stony, or in powder ; 
 a range of Alpine hills, or a few isolated gems ; a 
 succession of valleys, or a tract of verdant plains ; 
 the immense mass of the rock, or the minute 
 specimens of the cabinet are results of different 
 quantities, relative numerical proportions, mechani- 
 cally intermixed, or chemically combined with each 
 other, of only these elements BARYTES, STRONTIA, 
 LIME, MAGNESIA, ALUMINE, SILICA, and these of 
 rare occurrence, GLUCINA, ZIRCONIA, YTTRIA, 
 THORINA. 
 
 Barytes, strontia, lime and magnesia are 
 called alkaline, because they affect slightly certain 
 
230 CHEMISTKY OF POTTERY. 
 
 vegetable colours, much like the alkalies, and have 
 varied combinative potency with the acids ; the 
 others are called simple earths, because they do not 
 present either alkaline or aciduline properties on 
 tints, or chemical combination with the acids. 
 
 The alchemy of Davy has completely subverted 
 the previously prevalent opinions of chemists con- 
 cerning the earths in the purest state Nature or Art 
 can supply them. Their peculiarities render them 
 the connecting link of the alkalies to the metals. 
 For like the alkalies the earths act as bases, 
 solicited to combination by the acids, and forming 
 peculiar salts, usually with completely distinct pro- 
 perties from those of either acid or base, insoluble, 
 or only with difficulty soluble, in water ; and like the 
 metals, indifferent to volatilisation by heat. The 
 most probable analogies show that they are oxides 
 of certain metals, into which, however, they are not 
 convertible by all the usual methods of reduction, 
 and when so reduced by the most improved sugges- 
 tions of scientific research, the result possesses merely 
 an evanescent metallic existence, even if it be 
 hereafter proved that metals are not merely unoxi- 
 dated earths, or that there is clear dissimilarity 
 of composition in alkalies, acids, native metals and 
 metallic ores. Their metallic bases more nearly 
 approximate to the common metals than do those of 
 the alkalies, and themselves more closely than the 
 alkalies resemble metallic oxides. 
 
 On these subjects, and others correlative, cer- 
 tainly we are now on the eve of great discoveries. 
 There is known to be present with all pyrites, 
 usually in considerable quantity, an unmetallic 
 
THE EAETHS. 231 
 
 substance, or earth, which seems to be intermediate 
 between earth and metal ; yet to this latter state 
 current processes have failed to reduce it, as likewise 
 to determine its peculiarities. Under the metals 
 I have suggested the probable modus operandi of their 
 formation, to which I must refer the reader who 
 does not clearly understand the following detail : 
 This globe appears to have been partially under 
 galvanic influence, and thereby pre-disposed to 
 become metalline ; but either there has been a 
 cessation, or defective potency, of that agent in the 
 production of all metals, or it has not been suffi- 
 ciently long continued to perfect the degree of 
 change needful to elaborate the metal. For suitable 
 information on this subject, in vain have I examined 
 every modern work on chemistry to which I could 
 gain access. It is to be regretted that chemists of 
 the greatest ability have devoted so much attention, 
 or exhausted their energies, in mooting abstract 
 points, only useful in a scientific not practical appli- 
 cation ; those who have occasionally attended to 
 the resolving of the combinations of the earths 
 as yet do not appear to have more than merely, 
 en passant, directed their thoughts towards the 
 researches much more useful in the Arts of Life 
 the fusibility or infusibility, and other chemical 
 properties of the earths and stones. Not so was 
 the custom of their predecessors, however tainted 
 with fondness for alchemy Imperatus, Hiserne, 
 Wallerius and Pott. Much original information on 
 these subjects is given in the First Chapter of the 
 Second Part of this Work. 
 
232 CHEMISTRY OF POTTERY. 
 
 ALUMINE. 
 
 ALUMINE in a pure state (as in the very rare 
 corundum gems, the oriental sapphire and ruby, with 
 a little colouring matter) is without odour or savour, 
 fusible by the oxy-hydrogen blow-pipe only, and 
 soluble in test 1, and solution of caustic soda, whence 
 it is separable by the acids as a hydrate. It does 
 not affect the tints of blue vegetables, nor their 
 juices. Its absorbent properties capacitate it for 
 rapid combination with the colorific oxides of metals, 
 and it is frequently mixed with cobalt protoxides ; 
 also much used as a component of powders to 
 cleanse away oils. 
 
 Alumine is regarded as the oxide of a metal 
 named aluminum, because the earth is the base of 
 the salt alum. Only in very recent times have the 
 researches of Davy led to its development as a 
 compound of a peculiar metallic base with oxygen. 
 
 Processes. (1.) Pure Alumine. In 20 parts of warm dis- 
 tilled water dissolve 1 part of good alum ; then carefully drop in 
 solution of carbonate of soda to precipitate any spice of iron pos- 
 sibly present, and filter it out ; to the supernatant liquid add test 
 2, and by it soliciting to combination the sulphuric acid present, 
 the earth in white flocculence will freely precipitate. In its moist 
 state it is appropriated by the Manufacturers of printing blue. 
 For other purposes, filter out, wash well, dry at a white hea-t for 
 not less than one hour, to dissipate the moisture and any sulphuric 
 acid possibly present. 
 
 (2.) Aluminum. In a porcelain tube incandesce pure alumine 
 while a current of chlorine gas passes through to form a chloride 
 of alumine, which mix with potassium in a platinum crucible ; 
 
THE EARTHS. 233 
 
 <3over close up, raise the temperature very high, and the chlorine 
 will convert the potassium into potash, which, with aluminum will 
 remain in the crucible. The metal has resemblance to platinum, 
 with the brilliance of tin. When incandescent it is soluble in 
 dilute sulphuric or muriatic acid, and forms a very hard and 
 refractory button of alumine. The galvanic circle supplies similar 
 results. 
 
 Alumine exists more or less in almost every 
 mineral, and is one of the components most in quan- 
 tity present in clays, ochres, loams, boles, fuller's 
 earth, soils, rocks and strata of our globe. In its 
 pure state it is without grittiness between the teeth, 
 a smooth paste, soft to the touch, adhering to the 
 tongue, not soluble in water, yet combining with it 
 in every proportion, and at intense heat retaining a 
 portion thereof, at every degree above incipient 
 redness ; from the loss of water there is definite con- 
 traction or reduction, its volume being condensed, 
 not a portion fused (except in consequence of the 
 presence of water generated during the combustion 
 of the gases of the oxy-hydrogen blow-pipe) ; after 
 this baking scarcely can it be placed in the balance 
 scale ere its absorption of moisture from the atmo- 
 sphere increases its weight ; in a dry one to 15 per 
 cent., in a humid one to 33, and saturated to 51 
 and 54, and it retains 50 per cent, at the ordinary 
 temperature of the atmosphere. Moistened with 
 water the mass is cohesive, tenacious, ductile ; and 
 this plastic property capacitates it for being kneaded 
 into regular shapes for vessels, or moulded into 
 figures, which are rendered hard and durable by 
 the process of baking biscuit and glaze. 
 
 At very high temperatures alumine combines 
 
234 CHEMISTRY OF POTTEEY. 
 
 with the fixed alkalies and with most of the other 
 earths, a greenish and bluish tint characterising the 
 results of barytes or strontia. In ammonia alumine 
 is scarcely soluble, and not at all in solutions of 
 alkaline carbonates. With barytes or strontia it 
 forms two very distinct compounds : one, an insolu- 
 ble powder with plus of alumine ; the other, a soluble 
 salt, in solution, with plus of the alkaline earth. 
 
 CLAYS. 
 
 THESE aluminous minerals (for whose discri- 
 mination into species we yet need a clear and 
 distinctive characteristic) are very extensively dis- 
 tributed in the outer surface of the crust of our 
 planet, and consequently are readily available for 
 different Arts of Life in which they are useful. 
 They occur in opaque, non-crystallised masses, with 
 a dull, even, earthy fracture, easily scratched by the 
 nail or iron, and because of an adventitious sub- 
 stance present (oxide of iron as a spice, but never 
 as a component), when breathed on they exhale the 
 peculiar odour called argillaceous or earthy, not 
 perceptible in alumine or pure clay ; when pressed 
 to the tongue adhering closely, and imbibing the 
 moisture, so as not again to resign it until the tem- 
 perature is raised very high, retaining 10 per cent, 
 at 300 Fahrenheit. Because of this tenacity of 
 moisture, they readily are worked together into a 
 plastic paste for the various purposes of vessels, 
 figures, tiles, bricks, etc. 
 
THE EAETHS. 235 
 
 The species named Black Clay, because of the 
 presence of much carbonaceous ingredients, is further 
 distinguished by the peculiar property of evolving all 
 these during the intense heat of baking biscuit, and 
 becoming whiter in proportion to the quantity 
 present. It is usually mixed with one or more of the 
 other species. The Cracking Clay, so named by the 
 Brothers John and Thomas Wedgwood, of Burslem, 
 can be used only with much care of mixture with 
 the other kinds, and with flint, when it bakes very 
 white and makes firm ware. The Brown Clay re- 
 quires to be a long time exposed to the alternations 
 of the weather for disintegration, else it will not pass 
 through the lawns. The process of baking biscuit 
 renders it extremely white, and it is entirely free from 
 the disadvantage mentioned of the previous species 
 cracking while baking. Yet it is not constantly 
 introduced, because Manufacturers not acquainted 
 with its peculiar properties from its components and 
 proportions (a small spice of phosphoric acid that 
 renders needful the presence of some component with 
 potency to neutralise its action during the baking 
 biscuit that the lead of the glaze be not thereby 
 injured) have hitherto failed to divest it of the 
 potency to cause crazing. In some porcelains it is 
 very partially introduced in preference to the Blue 
 Clay, which is most used, because, whether in flint 
 ware or porcelain the baking biscuit is followed with 
 a whiteness (increased by more flint than any of the 
 other species will appropriate), a solidity of fabric, 
 and without the liability of the other kinds to crack 
 during or after baking. However comminute we 
 render any of these clays after once baking, the 
 
236 CHEMISTRY OF POTTERY. 
 
 cohesive property, on which depends the plasticity, 
 is absent until a solution is formed in some acid, and 
 an alkali causes precipitation. This has caused the 
 opinion that in their native state a gluten is present, 
 which heat destroys ; and it is further observed that 
 the alkalies themselves have trifling combinative 
 potency with the clays (or alumine) compared with 
 that in silica. 
 
 The following are the most correct analyses 
 I have been able to obtain of the clays and other 
 earthy minerals employed in this Manufacture : 
 
 Silica. Alumine. Iron. Lithia. Lime. 
 
 Common Pottery Clay, per cent. 60 33 3 3 -5 
 
 Ball Clay, Blue 64 35 1 
 
 Black 66 30 2 
 
 Brown 67 30 2-5 
 
 Cracking 68 31 1 
 
 Cornish Grauen 68 16 2 14 
 
 Clay (China) 71 28 -5 -5 
 
 Felspar, Kaolin 68 20 -5 12 
 
 Petuntse 60 20 20 
 
 Flint 98 1 -1 1. 
 
THE EARTHS. '237 
 
 SILICA. 
 
 SILICA (from the Hebrew selag, to burn or vitrefy, 
 whence also our word slag, something vitrefied), an 
 oxide of a peculiarly-combustible element, is a very 
 white, fine powder, without savour or odour, but a* 
 harshness when rubbed between the thumb and 
 finger, and a grittiness between the teeth ; not 
 glutinous when moist, retains about 26 per cent, of 
 water at the temperature of 70 Fahrenheit ; is in- 
 soluble in water alone, yet is held in solution in the 
 waters of the Iceland Geysers ; others precipitate 
 it as stalactites ; and it is secreted in the rinds of 
 grasses and equisetums as tabasheer. It is fusible 
 by the oxy-hydrogen blow-pipe, also with 3 parts 
 caustic potash, and 4 parts carbonate. 
 
 Silica is very abundant in Nature, probably 
 more so than all her other products together. It is 
 the chief component of all silicious minerals and 
 scintillating stones ; the great proportion of oxygen 
 present renders its combinative potency much similar 
 to that of exhibited acids ; in many of the gems it 
 has a spice of metallic oxide, either chemically com- 
 bined or mechanically mixed. As quartz it occurs, 
 in an almost pure state, in those large regular forms 
 resembling glass, and known as Rock Crystal ; and 
 in a less pure state we find it in immense masses, 
 beds, and elevations alone, and likewise in the 
 primitive mountain chains, in granites and the other 
 kinds of rocks. From these, by mechanical separa- 
 tion, it forms the well-known article of sand on the 
 
238 CHEMISTEY OF POTTERY. 
 
 sea-shore, the banks of rivers, and the low plains ; 
 and while alumine appropriates and holds water, 
 silica, in this state of sand, allows it to permeate, 
 filter itself from impurities, and become again suitable 
 for all the purposes for which it is intended by Nature. 
 Its peculiar combinative potency renders it not 
 obviously soluble in water, but its real solubility is 
 clearly demonstrable in Nature, by the numerous 
 crystals elaborated, and artificially, by the facts 
 adduced by Berzelius ; and further, that whenever 
 the compound result of fused silica 1 and potash 4 is 
 dissolved in water, and this solution is much diluted 
 with an additional quantity of water, the silica, as 1 
 to 1000, continues suspended therein, and is not pre- 
 cipitable by any acid or quantity thereof which may 
 be supplied. This is the true cause of its intimate 
 combination with the earths and alkalies. 
 
 Process. Silica is supplied in a pure state by the residuum 
 of fluor spar heated in sulphuric acid, by which fluorine evolves. 
 Also by this process : Take a small nodule of well-burned flint, 
 as white as is readily obtained (or rock crystal, or quartz), crush 
 it in paper, and triturate in a porcelain mortar to a fine powder, 
 in observance of that chemical law, that to facilitate solution we 
 bring solids into a comminute state, that we may thereby increase 
 the surfaces submitted to the solicitings of fluids ; mix it with 
 caustic potash 3, or carbonate of potash 4 times its weight, and for 
 the former use the silver crucible, for the latter, one very capacious 
 of earthenware ; slowly and gradually raise the temperature to a 
 strong red heat, and during forty minutes keep in this heat, and 
 with an iron rod preserve the effervescence sluggish ; then pour 
 the frit upon a dish of brass or copper, and when cold again pul- 
 verise. Dissolve in pure water, filter, and carefully pour into 
 excess of diluted sulphuric or muriatic acid (not the acid pour into 
 the solution, else glass, not silica, will be the precipitate), or into 
 a solution of muriate of ammonia, which will not dissolve any 
 
THE EARTHS. 239 
 
 portion whatever of the silica. Let the liquid repose not less 
 than twenty-four hours, then decant by a siphon, wash the 
 precipitate well with hot pure water, till all savour of acid and 
 alkali is removed ; then evaporate dry. For the alumine possibly 
 present, boil twenty minutes in sulphuric acid 5, water 5 ; filter, 
 wash well again with hot water, evaporate dry, and incandesce 
 the result. In this pure state it is refractory in the highest heat 
 of the potters' oven, and cases of its fusion have been ascertained 
 to result solely from the presence of a small portion of alkali not 
 previously recognised by the operator. 
 
 The silica thus obtained, carefully washed and 
 well dried, is almost wholly indifferent to the action 
 of every acid except the fluoric, which appropriates 
 65 per cent., and therefore so forcibly acts on glass ; 
 but it is readily solicited by a boiling solution of 
 caustic potash, soda, lithia, barytes, or strontia, and 
 the silicated potash by a boiling aqueous solution 
 of barytes, strontia, or lime, with alumine ; yet the 
 liquid is active on turmeric paper, and renders it 
 brown. The solution, evaporated, dried at 242 
 supplies a substance pale yellow, transparent, deli- 
 quescent, soluble in water (silica 2, soda 6, water 1), 
 and the concentrated solution is gelatinised by the 
 supply of acid equivalent to the soda. 
 
 SILICIUM. Mix dry silicated fluate of potash 2 
 parts with potassium 5 ; fuse in a porcelain crucible ; 
 the hydrogen will evolve, and pure silicium will 
 result, a brown powder, resembling charcoal in com- 
 bustibility, varying with the state of aggregation ; 
 and in its densest state it may be incandesced without 
 flame resulting. With some difficulty it is completely 
 combustible with carbonate of potash ; in vapour of 
 sulphur, into a grey sulphuret ; in chlorine, into a 
 limpid colourless fluid, with the odour of cyanogen ; 
 
240 CHEMISTEY OF POTTERY. 
 
 but not heated with nitre. To form silica it com- 
 bines as 200 with 208 of oxygen. 
 
 The composition of silica is best determined by 
 the experiments of Berzelius and John Davy. Ber- 
 zelius reduced silica by iron and charcoal ; in muriatic 
 acid separated the alloy of iron and silicium, which 
 latter combined with much oxygen. After deter- 
 mining the quantity of red oxide of iron, of carbon, 
 and of silica supplied by the alloy, he supposed that 
 silica has from 45*34 to 4775 per cent, of oxygen. 
 Stromeyer, by a different analytical process, con- 
 cluded that it was 55 per cent. Dr. Davy's analysis 
 of the triple fluate of silica and ammonia is, am- 
 monia 24*5, silica 46*357, fluoric acid 29143. Now 
 the oxygen of the ammonia, here the smallest quan- 
 tity, must exist in the silica in some multiple of a 
 whole number. But 24*5 of ammonia contain 11 -219 
 of oxygen, and the silica contains, in 46*35, 22*35 
 of oxygen. But 11*219 x 2 == 22*438. These show 
 how near to the absolute truth is the result supplied 
 by Berzelius ; while the probable accuracy of Davy's 
 conclusions shows the impossibility of silica contain- 
 ing 55 per cent, of oxygen. Again, Ekeberg's ana- 
 lysis of ytterite, most exact in its details, supplies 
 yttria 55*5, silica 23, oxide of iron (as by the analysis) 
 16*5, equivalent to 15*42 of pure black oxide of iron. 
 Yttria 55*5 has 10*3 of oxygen, silica 23 should have 
 10*9, and the black oxide of iron 15*42 has 3*5 ; now 
 3*5 x 3 = 10*5. As the silica, whenever present with 
 other components, must be in strict accordance with 
 the laws of definite proportions, the coincidence just 
 mentioned is an additional proof how near to the truth 
 approximates this determination of the composition of 
 
THE EAETHS. 241 
 
 silica. As it contains more than one volume, and 
 cannot be three volumes, the probability is that it 
 is two. This great quantity of oxygen present in 
 silica is one chief cause of its great utility in several 
 of the Arts of Life, and of its important introduction 
 and beneficial employment in the Manufacture of 
 fine earthenware, porcelain, and glass, because of its 
 ready combination with an alkali.* 
 
 * No person who knows Mr. Donowan can doubt that his 
 knowledge of philosophical chemistry is very extensive. How- 
 ever, to his celebrity the volume on the Manufacture of Porcelain, 
 in Dr. Lardner's Cyclopaedia, will not make any addition. Every 
 potter of ordinary acquirements will immediately denounce its 
 total deficiency of correct information. In his remarks on the 
 defect of ware, chipping off the edges, he states, that " the Chinese 
 prevent this by applying to the edges a mixture of charcoal [of 
 bamboo] powder and the glaze ; and when this is very dry the 
 vessel is covered with the glaze and baked." He opines that it 
 might be of great advantage to our Manufacturers to attempt 
 something of this kind, and for the purpose suggests the charcoal 
 of green [elder. He does not assign any reason for the Chinese 
 practice, that is, to supply additional fuel, that in the same time of 
 baking it may properly fuse the thick components of glaze sup- 
 plied to the edges. Neither does he once seeni to have troubled 
 himself to reflect on the great differences in the processes of King- 
 te-ching and Stoke-upon-Trent. He does not answer, because he 
 has not asked himself, these questions : Are English porcelains 
 liable to similar injuries? and, What chemical effect does the 
 charcoal produce? He mentions the caution used in preparing 
 the bamboo that the rind is peeled off, else the edges would 
 burst in baking. Still it has not occurred to his mind that the 
 silicic acid of the tabasheer of the rind, when its momentum is 
 excited by the high temperature of the potters' oven, would render 
 very brittle, and therefore of easy fracture, the glass resulting from 
 its combination with the alkalies present. This is the real cause of 
 
 E 
 
242 CHEMISTRY OF POTTEEY. 
 
 The almost general and constant momentum, in 
 some multiple of 4, of the combinative potency of 
 silicic acid on the alkaline earths in natural primary 
 mixing, as well as metallic oxides, and in like 
 manner determining them in series, also continuing 
 its potency when other acids have been exhibited to 
 produce separation, fully warrant the method herein 
 adopted of mentioning the numerous proximate com- 
 ponents of the many and various natural silicates of 
 alumine, in series, of simple combinations, and com- 
 plex compounds, the more clearly to develop the 
 composition of silicious minerals. 
 
 Each silicious mineral must of necessity be 
 compounded of the like number of silicates as there 
 are receptive atoms, those of oxygen ; each of which 
 is accompanied by other two active atoms, with the 
 antagonist potency of hydrogen, on the general 
 principle of separation and reunion, the mechanism 
 of atoms and of Nature. In each silicate the oxygen 
 atoms are precisely a third of the total number pre- 
 sent ; there must be likewise the same number of 
 atoms of silicium, and also the like number of atoms 
 of the other element which distinguishes the silicate. 
 Want of a clear understanding of this fact, probably, 
 has not diminished the errors of the Manufacturers. 
 Even to the present day, on no analysis of the clays, 
 
 the Indians producing fire by rubbing together two pieces of 
 bamboo ; as both have a coating of silica in their tabasheer, 
 sparks result from the friction, in like manner as from rubbing 
 two pieces of quartz together, an effect produced even in 
 water. 
 
THE EARTHS. 243 
 
 silicates of alumine, with which they are supplied by 
 dealers, can they place confidence, because not yet 
 has any explanation been published whether the 
 silicium, alumine, and oxygen are present in only 
 simple or in double or in triple proportions of com- 
 binative potency, and number of elements. What 
 
 1 wish to be understood is, that of the five kizids of 
 clay blue, black, brown, cracking, and Cornwall 
 they have no statement whether any, or more than 
 one, and which, as a compound has for its compo- 
 nents one particle each of silicium, aluminum, and 
 oxygen, equivalent to a hydrate of aluminum ; or of 
 
 2 oxygen, 1 aluminum, and 3 silicium, a double 
 silicate, of 1 particle of silicic acid and 1 particle of 
 silicate of aluminum ; or of 3 oxygen, 2 aluminum, 
 and 4 silicium, a triple silicate, of 1 particle of silicic 
 acid and 2 particles of silicate of aluminum ; and in 
 like progression. 
 
 Al. Sil. Ox. 
 
 Silicate of Aluminum Al. Ox. Sil. '6 4 8 
 
 Double Ditto Al. Ox. Sil. + Sil. Ox. Sil. 4-5 12 16 
 
 Triple Ditto Al. Ox. Sil. + Sil. Ox. Sil. + Al. Ox. Sil. 9 12 24 
 
 The determinations of these peculiarities are 
 not mere ideal speculations ; they are of vast im- 
 portance to the perfection of the Manufacture, which 
 must progress with the knowledge of all the materials 
 .employed. And yet the chemists of our day have 
 been so occupied with regularly playing off a number 
 of occult terms, for show of knowledge, that they 
 have scarcely attended to the facts obvious to 
 
 B2 
 
244 CHEMISTRY OF POTTERY. 
 
 common observers, nor allowed themselves leisure 
 and opportunity to investigate the mechanical pro- 
 cesses of Nature, that I cannot help the dread, that 
 for another age, and for results of experiments 
 instituted expressly for the purpose, is reserved the 
 credit of throwing that light upon these subjects, 
 which, for them to be accurately known, is indis- 
 pensable. 
 
THE EAKTHS. 245 
 
 FLINT. 
 
 FLINT is obtained in large supplies, to more than 
 100,000 tons per annum, from the vicinity of 
 Gravesend, Brighton, the Isle of Wight, and the 
 south-east coast of Ireland. In the form of nodules, 
 frequently approximating to a globular figure, of 
 sizes from that of a small apple to that of a cabbage, 
 flint is found in horizontal strata of chalk, varied in 
 fineness and solidity ; and as the strata do not wholly 
 touch each other, there is no solution of continuity 
 between the upper and the lower. When first quar- 
 ried the nodules always have a white opaque crust, 
 of an earthy, chalky appearance, in thickness varied 
 to two lines, with a loose texture, and much less hard 
 and heavy than the flint which it envelopes. And 
 after this coating has been removed, the action of 
 the atmospheric phenomena ere long again covers the 
 nodules with a second but extremely thin coating. 
 Vauquelin took some time to discriminate whatever 
 difference existed between flint and quartz, and 
 he was convinced that there is essential difference, 
 by him conjectured to be in the proportion of 
 combustibility of each. 
 
 The best flints are not very large ; in colour 
 blackish-brown ; the fracture has a greasy aspect, a 
 little shining, with the grain so fine as to be imper- 
 ceptible ; specific gravity 2'594 ; and having these 
 elementary atoms, according to both Klaproth and 
 Vauquelin: Silica 98', Lime *50 (or 51), Alumine 
 25, Oxide of Iron -25, Loss 1- (or Tl) = 100. 
 
246 CHEMISTBY OF POTTEEY. 
 
 Flint occurs in great plenty in common chalk, 
 in which it is deposited in tuberose masses, and in 
 pretty regular layers, each in an insulated state ; also 
 occasionally in veins in primary and transition 
 rocks. 
 
 The colour is usually grey, mingled with black, 
 brown, yellow and red. Fracture perfect and large 
 conchoidal. When cavities occur in it they are 
 sometimes lined with small quartz crystals having 
 the usual form ; lustre glistening or glimmering, 
 translucent ; blackish varieties, only so on the edges. 
 Hardness superior to rock-crystal, very fragile, and 
 easily broken by a smart blow ; specific gravity 2*575 
 to 2-594, 37 atoms silica = 74 + 1 water = 1'125 = 
 75-125. The alumine and iron merely spice the 
 silicate. 
 
 The manner of Nature's formation of flint is 
 a difficult geological problem ; and only will it, as 
 also that of chalk, be fully elucidated by intimate 
 acquaintance with the applications of chemical com- 
 binative momenta with respect to mineral products. 
 Both must have been produced by states of the earth 
 and atmosphere, which we only can imagine, but not 
 demonstrate by present facts. Some persons have 
 supposed flints to be concretions of organic remains ; 
 and Hacquet has laboured to show that it originates 
 from chalk, and is daily forming. Cavities in the 
 chalk are filled with nodules of flint. May we regard 
 these cavities as formed by gas evolved during the 
 deposition of the carbonate of lime modified to form 
 chalk, and while too impotent to reach the surface, 
 sufficiently potent to prevent the congestion of the 
 mass ? Have the silicic acid and water permeated 
 
THE EAETHS. 247 
 
 and filled these cavities, and therein remained until 
 solidified? One of my sons accidentally broke a 
 nodule of flint (still in my possession), which demon- 
 strates its having been formed by infiltration, what- 
 ever may have been the way in which the silicic acid 
 came in contact with the lime. The nodule is 
 elongated and hollow ; and its interior presents an 
 entire coating of minute crystals of quartz with a 
 slight discoloration from a precipitate of protoxide 
 of iron. I cannot but believe, that among the great 
 quantities of flint nodules daily broken by hand for 
 the mills, numerous instances are presented to verify 
 my remarks, although they pass unnoticed. 
 
 The introduction of flint into earthenware, along 
 with the finer clays of Devon and Dorset, greatly 
 promoted the whiteness of the ware ; although 
 I must acknowledge that uncalculated losses have 
 ensued therefrom, because of inattention to the pre- 
 cise quantity which would accomplish the desired 
 purpose, and of want of acquaintance with its 
 chemical properties. The merit of this introduction 
 is, by the general voice of the Staffordshire potters, 
 assigned to Mr. Thomas Astbury, of Shelton ; and it 
 is not too much for us to have expected that by the 
 natural bent of his genius he would have been much 
 more swayed, and would with indiscriminate ardour 
 have introduced every substance adapted to advance 
 the Art towards perfection. He can be excused only 
 on the ground of its possibly requiring efforts greater 
 than could be made by a person circumstanced like 
 him, to place himself in array against the prejudices 
 of the times, and for the practices of his compeers 
 
248 CHEMISTRY OF POTTEEY. 
 
 evince a disregard, exceeding what is warranted by 
 the current sum of philosophical knowledge. 
 
 The demand for his ware caused Mr. Astbury, 
 in 1720, to take a journey to London on horseback. 
 Ere he reached Dunstable his horse's eyes became so 
 disordered as to threaten immediate blindness, so 
 that on arriving at his inn he sought assistance from 
 the hostler for the disease, which demanded prompt 
 attention. The hostler put into the fire-grate a small 
 nodule of flint plentiful in that neighbourhood and 
 after it had become incandescent, he threw it into 
 water and then pulverised it into a very fine powder, 
 a little of which was blown into each eye of the horse, 
 and the copious discharge which ensued relieved and 
 cured them both. However, the attention of Mr. 
 Astbury had been further engaged ; he had noticed 
 the white appearance of the calcined flint, the 
 methods by which this, and its very fine state as 
 powder, were so easily attained ; and rightly conjec- 
 turing that its introduction as one of the materials in 
 his Art would improve his ware in whiteness, he 
 caused some of the coarse flints to be forwarded to 
 Shelton, where, on his return home, he had them 
 fired after the ware was baked, then pulverised in a 
 large mortar, and in the state of powder mixed with 
 pipe-clay in water, with which he washed the inside 
 of his hollow-ware ; and ultimately it was introduced 
 into the body. 
 
 All the notices by tradition supplied concerning 
 this person agree in the remarkable particular, that 
 although his intimate acquaintance knew him to be 
 very ingenious and acute, yet he managed to play 
 
THE EAKTHS. 249 
 
 his part as the most noted fool employed by Messrs. 
 Elers.at the Brad well Manufactory. Convinced that 
 the development of their processes would render an 
 important benefit to his countrymen, as well as to 
 himself, he undertook the task for which he was 
 well capacitated ; he humbled himself, and without 
 apparent regard sustained every kind of insult and 
 contumely which the others, masters and workfolks 
 thought proper to manifest towards him. He com- 
 pletely succeeded in his object, became a Manufac- 
 turer, and after his introduction of flint, his success 
 was much greater than he might reasonably have 
 expected. Yet his real modesty prevented that 
 justice being done to his merits by his contempora- 
 ries which will be readily and willingly awarded by 
 posterity.* 
 
 * As the details are rather remarkable, I make no apology for 
 stating them, as communicated to me by an old potter of 84 years 
 of age, in 1810, and also by Mrs. Smith, Astbury's grand- 
 daughter, of Lane-End, in 1814, having been introduced for this 
 purpose by Mrs. H. Close, of Hanley. Aware that the Messrs. 
 Elers employed only the most weak-minded persons with whom 
 they might meet, lest their manipulations and processes should 
 be divulged to the Manufacturers of Burslem, and knowing his 
 own command of temper would enable him to accomplish his 
 design, Astbury attired himself in suitable apparel, and with a 
 complete idiotcy of countenance and expression, presented himself 
 before the Bradwell operatives. His disguise was so complete 
 as to render him unknown to his neighbour Twyford ; and 
 although it was attempted to drive him away by cuffs, kicks, and 
 varied unkind treatment, from masters and idiotic workmen, he 
 submitted to all with ludicrous grimace, and evinced so small a 
 modicum of mental ability that he was employed on the premises. 
 Whatever food he obtained was always devoured, and only his 
 fingers were used to convey it to his mouth ; he could not recollect 
 
250 CHEMISTRY OF POTTEEY. 
 
 Flint is supplied in a liquid state to the Manu- 
 facturers in tubs of 40 pecks, of 8 Winchester quarts ; 
 
 any directions given him how to perform any of the labours re- 
 quired, but merely could assist any other person ; in few words,, 
 he sustained the character of the idiot almost two years without 
 being discovered, and during that period he regularly registered 
 every process he witnessed, and manipulation in which himself 
 or others were engaged ; made models of every implement 
 needed ; and acquired all the information requisite and useful in 
 the peculiar Manufacture pursued by Messrs. Elers. A fit of 
 sickness supplied opportunity for Astbury to quit their employ- 
 ment and resume his true character. 
 
 A remarkable coincidence I cannot help mentioning. Very 
 early in the eighteenth century, a Mr. Edward Allgood, chief 
 director of the Iron Works at Pontypool, South Wales (which: 
 had been commenced by his ancestors, but were become the 
 property of a Major Han bury, from some source not stated), 
 obtained information that peculiar methods for polishing wire 
 were practised by the operatives at Woburn in Bedfordshire.. 
 This much excited his curiosity (considering himself remarkably 
 clever), and interest rendered him extremely desirous to become 
 acquainted with these processes. He applied, accordingly, to- 
 several of the parties for this particular information, but in every 
 instance experienced a mortifying refusal. Determined, in despite 
 of every obstacle that might be presented, to obtain the desired. 
 object, he left Pontypool, and when arrived in the vicinity of 
 Woburn, he disguised himself in the garb of a low mimic and 
 buffoon ; and sustaining the characters with unusual good humour 
 and effect, as he passed through the town, his ludicrous and 
 amusing antics gradually gained him the attention and contribu- 
 tions of the workmen ; the repetitions supplied opportunity for a 
 little familiarity, and procured frequent ingress to the workshops- 
 most celebrated for excellence of productions ; in these he wit- 
 nessed, at the same time, the various processes and operations, 
 of the workmen ; and by waiting a suitable period he gained a 
 complete knowledge as well of the manipulations, the machinery, 
 and the requisite materials for fabricating the several kinds o 
 wire. 
 
THE EAETHS. 251 
 
 or 64 scores, 1280 Ibs. 32 Ibs. per peck, 64 oz. per 
 quart., and 32 oz. per pint. 
 
 When the slop-flint averages 32, or 28, or 24 oz. per pint, 
 the proportions of flint and water are as follows : 
 
 Pint. Quart. Peck. Tub. 
 
 Pint at Flint. Water. Flint. Water. Flint. Water. Flint. Water. 
 
 32 oz. 21 oz. 11 oz. 42 oz. 22 oz. 336 oz. 176 oz. 840 Ib. 440 Ib. 
 28 14 14 28 28 224 224 560 560 
 24 7 17 14 34 112 272 280 680 
 
 These are readily verified. When three pints 
 of slop-flint, at each of the respective weights, are 
 carefully evaporated and dried, the results will be 
 found 21, 14 and 7 ounces. Again, from a pint of 
 water, at 20 ounces, abstract sufficient to admit 
 7 ounces of dry flint, and the mixture is found 
 to weigh 24 ounces ; when other 7 ounces are 
 added, the weight is 28 ounces ; and when a third 
 7 ounces are added, the weight is 32 ounces, or 
 precisely that at which it should be supplied. And 
 from this it will be clear, that if only a quarter of an 
 ounce in the pint be wanting in flint, there will be 
 17J Ibs. deficient in the tub ; and from this, and like 
 causes, doubtless many errors have arisen in slip- 
 making. 
 
 Potting. As in preparing the calcined flints and felspar, for 
 the pan in the mill, weight of pressure and percussion are 
 requisite ; the principle of the pile-engine is adopted the falling 
 with acceleration of a loaded beam or pestle, shod with iron ends. 
 On a strong shaft are fixed single arms, placed a few inches 
 
252 CHEMISTRY OF POTTERY. 
 
 asunder, and forming the radii of a hexagon ; on the end of each, 
 at a right angle, is fixed a stout plug ; and the motion of the shaft 
 brings the plug of each arm in succession beneath another plug 
 firmly fixed on the beam, or stamper, and after lifting the beam 
 a certain height, quits it, and the weight of the beam by atmos- 
 pheric pressure also brings it down on the minerals upon the 
 strong grate, and as they are crushed they fall through, ready to 
 cast into the vat. 
 
 In the noise of the stampers of the crushing process their 
 rebounding is comparatively sonorous, occasionally at other 
 times a dead blow ; but on a first visit the shock on the nervous 
 system baffles description ; there is caused a painful jarring, the 
 sense of hearing is much affected for some minutes, the attempts 
 to converse are superseded by the voice being incapable of audible 
 articulation ; and some degree, of lassitude is immediately 
 produced. 
 
THE EAETHS. 253 
 
 LIME. 
 
 LIME, the very caustic protoxide of the pure 
 caustic alkaline metal calcium in its perfectly 
 pure state as obtained by burning in a crucible at 
 least two hours' time, at a white heat, calcareous 
 spar, Carrara white marble, or clean oyster shells 
 (which for tests should be closely bottled from air) 
 is white, moderately hard, easily pulverised, has a 
 peculiar odour, burning-hot savour, and corrosive 
 potency on animal substances ; specific gravity 2*3 ; 
 the blue juices of vegetables by it become first green 
 and afterwards yellow. 
 
 Neutralised by carbonic acid, as limestone, 
 every part of the globe presents it in great plenty ; 
 it also occurs plentifully as marble, chalk, calcareous 
 spar (coloured, or perfectly white and transparent), 
 and stalactites. From the earliest ages, after being 
 burned into lime, that is, kept some hours at a white 
 heat, by which the carbonic acid gas is dissipated, 
 and the caustic property again restored in quicklime, 
 it has been known and employed with the addition 
 of one-third of water as mortar, and in its applica- 
 tion as cement it again becomes carbonated into 
 artificial limestone. 
 
 When a little water is sprinkled on some dry 
 fresh-burned lime it is solicited, when hot, at 212, 
 with the momentum of 0*00078, and when cold, at 32, 
 with that of 0'00152 (first noticed by Dalton, one of 
 the few original thinkers) ; much vapour arises, and 
 the heat evolved is about 800, which would ignite 
 
254 CHEMISTRY OF POTTEEY. 
 
 some inflammable substances ; the mass falls into a 
 protohydrate of lime 75'68, water 24'32, the water 
 being more solidified than in ice. Therefore, as 
 quicklime in its perfectly dry state swells from the 
 moisture of the atmosphere, there scarcely needs be 
 any surprise in the mind of a reflecting person, that 
 this would cause to flee, upon change of temperature, 
 vessels whose clay has it as one component. Yet 
 this fact seems to have been overlooked by the 
 Manufacturers in reference to Paris white, and it 
 equally regards the use of bone earth. When 
 much if not all the water of phosphoric acid com- 
 bined with the lime in bone has been dissipated, 
 only the greatest care can prevent its supplying itself 
 again from the atmosphere, and as the lime itself 
 is, by the baking process, rendered caustic, it will 
 similarly solicit moisture from the same source, each 
 of which causes will soften the ware. 
 
 EARTH OF BONE. Phosphate of Lime. This, in 
 its prepared state, is a white powder, without odour, 
 caustic savour, insoluble in water, but soluble in 
 nitric, muriatic and acetic acids ; precipitable un- 
 altered by test 2, and at a very high temperature 
 fusible into a white enamel. Its general refractory 
 nature, when a component of the cupels employed in 
 metallurgy, may have suggested its employment in 
 soft porcelains, where in addition to its correcting 
 any discoloration from peroxide of iron in the clay, 
 it aids the production of translucence ; but I am not 
 aware of the person by whom was made the first 
 bone china. 
 
 Scheele first published, but Gahn was first 
 .successful in, the analysis of the earth of bones, and 
 
THE EAETHS. 
 
 255 
 
 -exhibited it as phosphate of lime ; and his sagacity 
 is the more entitled to attention, because the native 
 phosphate of lime has proved too difficult for the 
 processes of very celebrated chemists. In p. 68, 
 vol. xxxiv., Ann. de Chimie, are the truly interesting 
 researches of Herat Guillot, on the several com- 
 ponents of the different kinds of bones, which are 
 presented in a condensed form below : 
 
 Names of the several Substances employed. 
 
 Propor 
 
 Gela- 
 tine. 
 
 tions of 
 
 Phos- 
 phate of 
 Lime. 
 
 Carbo- 
 nate of 
 Lime. 
 
 Loss. 
 
 Human bones taken from a burial ground, per ct. 
 
 16- 
 23- 
 3- 
 25- 
 9- 
 16- 
 1-5 
 17- 
 9- 
 6- 
 12- 
 6- 
 21-5 
 18- 
 12- 
 24- 
 27- 
 3- 
 2-5 
 2- 
 8- 
 1-5 
 0-5 
 
 67- 
 63- 
 93- 
 54- 
 67-5 
 70- 
 90- 
 52- 
 85- 
 72- 
 64- 
 45- 
 60-5 
 14- 
 85-5 
 64- 
 57-5 
 2- 
 
 o- 
 
 12- 
 
 o- 
 o- 
 o- 
 
 1-5 
 2' 
 2- 
 
 15-5 
 2- 
 2- 
 21- 
 22-25 
 13-5 
 7-5 
 30- 
 5- 
 20-5 
 23- 
 48-5 
 17-5 
 28- 
 2-25 
 11-15 
 14-5 
 23- 
 31-5 
 26- 
 24- 
 48-5 
 46- 
 
 Bones of the ox 
 
 calf 
 
 horse 
 
 1-25 
 0-5 
 1- 
 1- 
 1- 
 1-5 
 1- 
 0-5 
 0-5 
 40- 
 0-25 
 
 o-i 
 
 1- 
 72- 
 66' 
 60' 
 68- 
 50- 
 53-5 
 
 
 elk P . 
 
 hog 
 
 "^ 
 
 chicken 
 
 pike 
 
 carp 
 
 viper 
 
 
 Teeth of the horse 
 
 
 Stags' horns ... 
 
 Egg-shell 
 
 Mother-of-pearl 
 
 Crabs'-eyes 
 
 Shell of the cuttle-fish . . 
 
 White coral 
 
 Bed ditto... 
 
 Processes. A solution of muriate of lime treat with solution 
 of phosphate of soda ; leave to repose 24 hours ; there will be a 
 precipitate of neutral phosphate of lime, 1 P + 1 L + 2 Water. 
 Ee verse the details. To the solution of phosphate of soda 
 gradually add muriate of lime ; when almost equivalent to the 
 former leave to repose, as before, and the precipitate will be a 
 sub-phosphate of lime, similar in composition to calcined bones 
 as used for introducing into soft porcelain. 
 
256 CHEMISTEY OF POTTEKY. 
 
 PLASTER OF PARIS, Gypsum, Sulphate of Lime, 
 is obtained from Chelaston, near Derby, and from 
 Beacon Hill, near Newark, Nottinghamshire. It is 
 without odour or savour, specific gravity 2*31, is 
 soluble in 450 of hot water, and 500 of cold ; it is 
 fusible by a moderate heat ; is separable by carbon- 
 ated alkalies, and decomposed by ignition with 
 charcoal. It is prepared for the Manufacturer's 
 purposes moulds for vessels and figures by being 
 ground between mill-stones, and afterwards evapo- 
 rated on a long brick trough, beneath which are flues 
 for the passage of heat from the fire. This process 
 is named boiling the plaster, because the escape of the 
 moisture causes decrepitation and effervescence. At 
 160 Fahrenheit it is completely prepared ; and after- 
 wards it most quickly solicits to combination water, 
 or other neutral liquid, becomes hot, and rapidly 
 solidifies. 
 
 Mould Making. Moulds are formed in the following manner : 
 The statue or figure to be copied is first oiled, to prevent it from 
 cohering with the gypsum. A quantity of liquid plaster, sufficient 
 for the mould, is then poured on, immediately after being mixed, 
 and suffered to harden. If the subject be a bas-relief, or any figure 
 which can be withdrawn without injury, the mould may be con- 
 sidered as finished, requiring only to be surrounded with an edging. 
 But if it be a statue, it cannot be withdrawn without breaking the 
 mould, and on this account it becomes necessary to divide the 
 mould into such a number of pieces as will separate perfectly from 
 the original. These are taken off from the statue, and when after- 
 wards replaced, or put together without the statue, they constitute 
 a perfect mould. This mould, its parts having been oiled to pre- 
 vent adhesion, is made to receive a quantity of plaster, by pouring 
 it in at a small orifice. The mould is then turned in every direc- 
 tion in order that the plaster may fill every part of the surf ace , 
 and when a sufficient quantity is poured in to produce the strength 
 
THE EARTHS. 257 
 
 required in the cast, the remainder is often left hollow, for the sake 
 of lightness and economy of the material. When the cast is dry 
 it is extricated by separating the pieces of the mould, and finished 
 by removing the seams and blemishes with the proper tools. Casts 
 of plaster are varnished by a mixture of soap and white wax in 
 boiling water. A quarter of an ounce of soap is dissolved in a pint 
 of water, and an equal quantity of wax afterwards incorporated. 
 The cast is dipped in this liquid, and after drying a week is 
 polished by rubbing with soft linen. The surface produced in this 
 manner approaches to the polish of marble. When plaster casts 
 are to be exposed to the weather, their durability is greatly 
 increased by saturating them with linseed-oil, with which wax 
 or rosin may be combined. When intended to resemble bronze, 
 a soap is used, made of linseed-oil and soda, coloured by the 
 sulphates of copper and iron. Walls and ceilings are rendered 
 waterproof in the same way. 
 
 If the form or position require it, the limbs are cast separately, 
 and afterwards cemented on. Moulds and busts are obtained in a 
 similar manner from living faces, by covering them with new 
 plaster, and removing it in pieces as it becomes hard. It is 
 necessary that the skin of the face should be oiled, and during 
 the operation the eyes are closed, and the person breathes through 
 tubes inserted in the nostrils. Elastic moulds have been formed 
 by pouring upon the figure to be copied a strong solution of glue. 
 This hardens upon cooling, and takes a fine impression. It is 
 then cut into suitable pieces and removed. The advantage of the 
 elastic mould is that it separates more easily from irregular sur- 
 faces, or those with uneven projections and undercuttings, from 
 which a common mould could not be removed without violence. 
 Glue Moulds for Casting. The body to be moulded, pre- 
 viously oiled, must be secured one inch above the surface of a 
 board, and then surrounded by a wall of clay distant about an 
 inch from its sides ; the clay must also extend rather higher than 
 the contained body ; into this warm melted glue, as thick as possi- 
 ble, is to be poured, so as to completely cover the body to be 
 moulded : the glue is to remain till cold, when it will have set into 
 an elastic mass. Having removed the clay, the glue is to be cut 
 into as many pieces as may be necessary for its removal. 
 
258 CHEMISTRY OF POTTERY. 
 
 MAGNESIA. 
 
 MAGNESIA, one of the elementary earths, with 
 a metallic base, magnesium, is found native, as a 
 hydrate, a soft white powder, with scarcely any 
 savour, devoid of odour, innocuous compared with 
 lime, is slightly soluble in water, yet with it never 
 forms a ductile adhesive mass ; reddens turmeric 
 paper, and changes vegetable blues and violets to a 
 green tint (yet these effects are not produced by the 
 water filtered from the earth itself after agitation 
 therein) ; is not dissolved by solutions of alkalies or 
 the alkaline earths ; has more resemblance to earths 
 than the alkalies ; alone it is refractory at the highest 
 temperature, yet with lime and alumine and silica it 
 fuses into a porcellaneous mass ; yet not when with 
 barytes or strontia. As a component of some of the 
 rocks which form the crust of the globe, steatite, and 
 serpentine, it is in considerable quantity ; and also 
 with lime, in very extensive formations. The per- 
 fect separation of these two is an extremely interest- 
 ing problem in chemical analysis, and because of 
 its difficulty some excellent chemists have supposed 
 magnesia a modification of lime. The magnesian 
 limestone is sooner rendered caustic, at a loss of 
 about 60 per cent., than the other, because this more 
 solicits to combination carbonic acid. The earth 
 itself has been very little employed in the Arts of 
 Life ; and although ordinary limestone, certainly of 
 a good quality, has been some time introduced as 
 Paris white, I am not aware that the magnesian 
 limestone has been submitted to trial. 
 
THE EARTHS. 259 
 
 Process. In distilled water dissolve sulphate of magnesia 
 (Epsom, salts), filter, add test 1, and the precipitate will be pure 
 magnesia ; filter out, wash well, evaporate dry, incandesce, and 
 keep in a w r ell-stoppered phial from the air. The sulphate of 
 magnesia, moistened, in the galvanic circuit in contact with 
 mercury, was decomposed into its basic metal, white, much like 
 silver, and with a specific gravity of 1*780. 
 
 As alumine solely by many has been supposed 
 the only earth really useful in the fabrication of the 
 best porcelain, there seems the more necessity and 
 propriety in recording the following remarks ; and 
 especially as there is a probability that the vicinity 
 of Epsom would supply some of the earth in question, 
 by which the trial could be properly made : 
 
 At Castellamonte, in Italy, and at Baudissero, 
 nine miles from Ivree and Brozzo, in Canavais, 
 Department of the Loire, is quarried a porcelain 
 earth, or clay, compact as the hardest chalk, amor- 
 phous, white as ceruse, without argillaceous odour, 
 not adhering to the tongue, so slightly affected by 
 water as not to form a solid paste, yet agglutinates 
 and contracts a little by drying at 350 ; specific 
 gravity 2 -800. The former, according to Guyton, 
 has magnesia 26 '3, silica, 14*2, carb. acid 46, water 
 12 ; the latter, according to Bucholz, has magnesia 
 46 '0, carb. acid 51, with a trace of alumine, lime, 
 manganese and water. It is employed with clay 
 in the fabrication of crucibles not affected by the 
 file, and of stone ware ; and with silica, in that of 
 very fine porcelain, by Gioannetti, at Vineuf, being 
 regarded as very excellent for that purpose. I 
 should not be much surprised if ultimately it be 
 
 found that the component of Nankin porcelain, 
 
 s 2 
 
260 CHEMISTKY OF POTTERY. 
 
 whose nature and use are so extremely carefully 
 concealed by the Chinese potters, is a magnesian 
 earth, or a silicate of alumine and magnesia. 
 
 In 1805, December 22, that eminent chemist, 
 Proust, of Madrid, thus addressed Vauquelin : "We 
 are going to-morrow to see the Manufacture of por- 
 celain, under the direction of M. Sureda, who was 
 brought up to this Art in the manufactory at Sevres, 
 and now makes a most beautiful porcelain, of a much 
 harder texture than yours. This is not effected by 
 kaolin, but with the spuma marls [Meerschaum of 
 Werner], a silicious magnesian-stone, found in the 
 neighbourhood of Madrid. We shall send you some 
 specimens which will astonish you. He covers his 
 biscuit with feldspars of Gallicia, which are very 
 beautiful. The stone would be very excellent for 
 the formation of chemical furnaces. When taken 
 from the quarry it is soft, and admits of being cut, 
 like soap. Furnaces made of this stone are ex- 
 tremely light, and never undergo fusion, however 
 high may be raised the temperature. Besides mag- 
 nesia, silica, and some particles of argil [alumine] 
 and lime, this stone contains a portion of [alkali] 
 potash, which contributes not a little to the superior 
 qualities of the porcelain." The information con- 
 tained in this letter I regard as very important, 
 when we refer to the time of its being written. 
 
 Steatite. The soapstone, employed in the 
 Swansea China Manufactory, is from Mullyan 
 Churchtown, and from a vein of serpentine near the 
 Lizard Point. It is greenish-white, tinged yellowish 
 sometimes, has a fine earthy texture, unctuous to the 
 touch, soapy lustre, infusible alone before the blow- 
 
THE EARTHS. 261 
 
 pipe. When first quarried, can be kneaded like 
 dough ; but after being some time exposed and 
 deprived of part of its moisture, its edges become 
 translucent, though it can be scratched by the nail, 
 silica 44, alumine 10, magnesia 24, water 22. 
 
 Having business which brought me to Swansea, in 1831, I 
 visited both Manufactories, and entered into free conversation with 
 several of the artisans. The whole of the china department at 
 Mr. Dilwyn's was discontinued, because the principal himself 
 was disgusted with the frequent failures, and consequent sacrifices 
 of capital, of the person to whom he confided the management, as 
 body and glaze were constantly unsuitable for each other, and 
 guessing usually rendered the affair worse. I felt wishful to obtain 
 some of the body clay and the fluid glaze for analytic investi- 
 gation, that I might have suggested the probable cause and 
 also the remedy ; I confess, hoping also for a douceur from the 
 principal on the information being communicated. But I failed 
 to obtain them, and my general remarks were similar to speaking 
 to a person in an unknown tongue. 
 
262 CHEMISTRY OF POTTEKY. 
 
 BARYTES. 
 
 BARYTES (from barm, heavy, a peculiar charac- 
 teristic of its natural combinations), one of the 
 elementary earths, the oxide or balanced alkali of 
 the metal Barium (B 17*5 + 4 Ox.), the most potent 
 (and strontia next) of the alkaline bases. As hydrate, 
 it is extremely poisonous if taken into the stomach ; 
 its colour is greyish-white, specific gravity 4 ; it is 
 without odour ; its savour is more harsh and caustic 
 than lime ; in its native state it is porous and easily 
 pulverised ; with less violence, yet like the fixed alka 
 lies, it corrodes the animal fibre to which it is applied ; 
 like lime, it slakes in air, and falls to powder by ab- 
 sorption of moisture ; it is soluble 5 per cent, in water, 
 at 60, and about 50 at 212 ; the solution, like the 
 hydrate, possessing the distinctive alkaline potency of 
 rendering vegetable blues and purples of a green tint ; 
 as the liquid cools beautiful prismatic crystals form ; 
 and by soliciting the carbonic acid of the atmo- 
 sphere, like lime, there is formed a pellicle on the 
 surface of the liquid. By the rise of temperature it 
 hardens, and has a bluish-green tint. The blow-pipe 
 flame causes it to intumesce in globules, and enter 
 the charcoal support, because of the presence of the 
 water of crystallisation. During fusion the hydrate 
 will combine with several of the earths and metallic 
 oxides, rendering them soluble in acids or in water ; 
 and whether alone or with other elements, as re- 
 agents, the employment is of great importance for 
 the purposes of scientific illustration by analytical 
 
THE EARTHS. 263 
 
 processes. Thus, either as a nitrate or muriate, ex- 
 hibited to detect the presence of sulphuric acid, the 
 other acid will appropriate the base, and the earth 
 combined with the sulphuric acid will precipitate as 
 an insoluble powder. The mineral kingdom supplies 
 great plenty of it, combined with sulphuric acid, and 
 less frequently with carbonic acid. 
 
 Processes 1 (Cheapest and Best). Mix well of the mineral 
 sulphate in powder 8 parts, muriate of soda 4 parts, charcoal 
 powder 1 part, bring into a state of incandescence, and during one 
 hour keep occasionally stirring the assay. The muriate of soda 
 solicits the oxygen, and thereby facilitates the decomposition. 
 When cool, crush the sulphuret coarsely, add it to 32 parts of 
 water, raise the temperature to 212, for five minutes, quickly 
 filter, and keep in close phials ready for further processes. 
 
 2. The powders of sulphate of barytes and charcoal, 2 and 1, 
 subject to very high temperature four hours (as in the mouth of a 
 fired-up oven) ; mix well in boiling-water whatever is soluble ; filter 
 the liquid, add carbonate of soda, the white precipitate filter out, 
 wash well, again mix with charcoal powder, and incandesce two 
 hours ; then again cast into boiling-w 7 ater, and with paper cover 
 close the vessel ; powerful reaction will be manifested ; the 
 barytes will be soluble therein, and two new products result, of 
 the crystals, and the liquid ; and will, as the temperature falls, 
 form the crystals, which collect for use ; and the barytic liquid 
 left can be evaporated, and will present a further supply. 
 
 3. Because of the great combinative potency of the earth and 
 the sulphuric acid, only : partially affected by the presence of 
 charcoal in high temperatures, and the difficulty of raising to a 
 sufficiently high temperature a mineral, when in company with 
 so sluggish a conductor as charcoal, only does this process 
 succeed at very high temperatures. 
 
 4. The powders as above, 4 and 1, incandesce three hours ; 
 then dissolve in boiling water, and by a syphon quickly decant 
 the liquid ; acidulate with test 25 (or 4. The native carbonate 
 dissolve in test 25) ; evaporate, crystallise, incandesce the 
 crystals, cover close, cool, and keep in a well-stoppered phial. 
 
264 CHEMISTRY OF POTTERY. 
 
 5. To obtain test 30. The liquid of process 1 treat with test 
 26 until no more of test 14 evolves ; filter, and wash the filter with 
 distilled water at 212 ; then evaporate till a pellicle commences ; 
 re-filter, and allow repose to crystallise ; separate the crystals ; 
 again evaporate the liquid, and the process repeat until all the 
 barytes is obtained ; mix all the crystals, and pulverise ; add 
 boiling pure water, again evaporate, and select the best crystals 
 for keeping, and the ley preserve as barytic water, to mix with 
 equal quantity of solution of borax for a certain glaze. The test 
 36 must be obtained by substituting test 25 for 26 as above. 
 
 When the hydrate supplied by process 2 is 
 again incandesced, it will (but that by 3 will not) 
 fuse and assume the appearance of oil. We, by 
 igniting crystallised barytes obtain an alkaline earth, 
 protoxide of barium, combined with water (B 17*5 + 
 4*5 W), concerning which, Berthollet says, " the 
 earth is engaged with a substance which diminishes 
 its action on other bodies, which renders it more 
 fusible, and which gives it by fusion the appearance 
 of glass." 
 
 Sulphate of Bar y tea. Cauk stone, heavy or pon- 
 derous spar, is by Nature presented in a variety of 
 beautifully-crystallised forms. It is that very heavy 
 brittle flesh-coloured mineral, with a foliated texture, 
 found plentifully in copper mines, and frequently 
 accompanying galena, or common lead ore, of which 
 it often forms the gangue ; supposed to be lime and 
 sulphuric acid, but which Galen first proved is a 
 compound of sulphuric acid and the earth which 
 Scheele discovered; specific gravity 4*5, B 17*5 + 
 20 s. acid. At 30 Wedgwood, fuses into a white 
 opaque mass. 
 
 Sulphate of barytes decrepitates before the blow- 
 pipe, but is not easily fused, which distinguishes it 
 
THE EARTHS. 265 
 
 from sulphate of strontian or of lime. Its particle 
 is 1 atom sulphuric acid + 1 atom barytes. 
 
 In Strontian lead mine the common gangue of 
 the galena is a compound of '2 atoms sulphate of 
 lime and 5 atoms sulphate of barytes ; and in York- 
 shire, between Leeds and Harrowgate, is a species 
 of 9 atoms sulphate of lime + '2 atoms sulphate of 
 barytes. 
 
 Carbonate of Barytes. Rats stone, Witherite, 
 is greyish-white, semi-translucent, glistening, bladed 
 or fibrous in structure, frequently with small cavities 
 lined with minute crystals ; specific gravity 4*3, 
 B 17 '5 + 11 carbonic acid. 
 
 There is a species compounded of 1 atom of 
 .sulphate of barytes + 2 atoms carbonate of barytes. 
 
 The crystals of carbonate of barytes are small 
 and semi-transparent ; the massive varieties are only 
 translucent. Before the blow-pipe it fuses readily 
 into a clear glass, which in cooling becomes a white 
 enamel. On charcoal it effervesces much, becomes 
 caustic, and then sinks into the support. With 
 borax and phosphate of soda it melts into a clear 
 glass, which becomes opaque and white on cooling, 
 when the quantity of the carbonate of barytes is 
 proportionate to that of the fluxes. 
 
266 CHEMISTRY OF POTTEEY. 
 
 FELSPAR. 
 
 FELSPAR is the generic name of the mineral, 
 which in its species is next to quartz most generally 
 diffused in the crust of the globe. Its colours vary 
 in the species from grey- white, brown, yellow, and 
 verdigris-green ; inferior to quartz in hardness, yet 
 not scratched by the knife ; specific gravity 2*6 ; 
 with vitreous lustre ; in the American species recently 
 introduced, crystallised ; in those of Middletown 
 Hill, Montgomeryshire, broad foliated (best for 
 glaze) masses, rarely granular (best), occasionally 
 quite compact (for body) ; in the blow-pipe flame, 
 on charcoal support, semi-transparent white vitreous 
 assay, but only at a very high temperature do the 
 edges fuse into a semi-transparent vesicular glass. 
 
 Though felspar is one component with quartz 
 and mica of the granite, it must be understood that 
 the hardness of this conglomerate will greatly depend 
 on the species of felspar, hereafter noticed, as con- 
 taining the least alkali.* Often is the felspar found 
 in concrete masses separately from the other com- 
 ponents of granite, forming irregular beds of varying 
 extent. Of the difference in the nature of its species, 
 an idea may be formed from the annexed weights of 
 the stone in cubic feet and inches : 
 
 * Ignorance of this peculiarity has caused the rejection of ex- 
 cellent grauen by persons who trusted to guesses. Even a few days 
 before this sheet went to press, a person (who manages one of the 
 Manufactories belonging to the gentlemen who own my residence) 
 showed me a large quantity of excellent grauen, when properly 
 treated, but which had till then been employed merely to form the 
 sides and butments of the flint-kilns at the Greenfield Mill. 
 
THE EARTHS. 267 
 
 Ciibic Foot. Inches. 
 
 China 2385 149-1 0-086 
 
 Siberia 2368 145-3 0-085 
 
 Salberg 2229 140-1 0-079 
 
 Passau 2290 143-4 0-080 
 
 Bayonne 2312 144-5 0-082 
 
 Limoges 2341 146-4 0-084 
 
 Sevres 2146 134-1 0-077 
 
 Middletown Hill 2370 147*2 0'085 
 
 The components of these varieties are equally 
 different in analysis. A crystallised specimen, from 
 Stella, a part of St. Gothard, by Vauquelin, and the 
 other kinds mentioned, supply the following : 
 
 Crystal. Green. Fl. Red. Passau. Salberg. Uton. Middletown Hill. 
 
 Vauquelin. Rose Buchoby. Godon. Vauq. white, b. gr. green. 
 
 Silica 64-0 63-0 67-0 62-5 68-0 64-5 6OO 64-0 68'0 
 
 Alumine 20-0 18-0 17'0 22-0 20-0 24-5 22-0 24-0 20-0 
 
 Alkali (Lithia) 14-0 14-0 14-5 14-0 11-0 8-0 16-0 10-0 10-0 
 
 Lime 2-0 3-0 1-5 -75 1-0 3-0 2-0 2-0 2-0 
 
 Spiced with Iron oxide 
 
 100-0 98-0 100-0 99-25 100-0 100-0 100-0 100-0 100-0 
 
 The correspondence of several of these to the 
 principle assumed at page 48 must occur to every 
 attentive reader of this work, and will render obvious 
 the real cause of the difference in the two kinds 
 of felspar for the Manufacture. In the white the 
 greater dose of alkali increases its fusible property ; 
 in the green the extra dose of silica renders it more 
 refractory ; and in the intermediate kind the compo- 
 nents are in their natural proportions, in round 
 numbers : Silica 15 x 4 + Alumine 6x4 + Lithia 
 4x4 = 100 ; Silica 16 x 4 + Alumine 6x4 + 
 Lithia 3 x 4 = 100 ; Silica 17x4 + Alumine 6x4 
 + Lithia 2x4== 100. The regularity of Silica and 
 Alumine is very remarkable ; but the irregularity of 
 
"268 CHEMISTRY OF POTTERY. 
 
 the alkali (however we call it potash, lithia, lime or 
 oxide of iron ; as many of the analyses made prior to 
 Arfwerdson's determining that it was the atone alkali), 
 induces an opinion, that galvanic agency, not yet 
 developed, operates on the principle of the mineral, 
 and causes the result mistaken for lime. Certainly 
 so minute a proportion of this earth, and not in the 
 regular quantity of its combinative potency, does 
 warrant the belief that some unknown cause is here 
 in operation. 
 
 The lamp of chemistry sheds an effulgence on 
 the peculiarities of minerals in analysis exhibiting 
 the presence and excess of useful or deleterious 
 components, not supplied by descriptive characters. 
 And the information is absolutely needful to the 
 intelligent Manufacturer, no longer as a matter of 
 conjecture. This will always determine the relation 
 of minerals. The petalite of Sweden and that of 
 Dublin differ very little, if my analysis and those of 
 Arfwerdson and Gmelin be correct. Not but that I 
 fear that one has more than the proper quantity of 
 silica. And I feel gratified with the approximation 
 of the second to the general principle of this work. 
 Indeed, the more I notice analyses, the more am I 
 attached to the hypothesis. 
 
 Arfwerdson. Gmelin. Dublin specimen. 
 
 Silica 79-212 74-17 72-18 
 
 Alumine 17-225 17-41 18-28 
 
 Lithia 5-761 5-16 6-10 
 
 Lime 0'32 1-14 
 
 Water 2-17 2-20 
 
 Loss -77 -5 
 
 100-40 
 
THE EAETHS. 269 
 
 Processes (1.) In a silver crucible put 10 grains of felspar 
 powder and 40 grains of hydrate of potash, also in powder; fuse 
 them together fifteen minutes, a. Add test 26, and with glass cane 
 stir till all is dissolved, then decant into a capsule and evaporate 
 dry ; again dissolve in test 26, and filter out the silica ; wash well, 
 dry, ignite, and weigh (about 6'5 grains, or 64 per cent.), b. The 
 washings add to the aciduline liquid ; alkalinise by test 2, the pre- 
 cipitate filter out, wash well, evaporate, and dry. c. The liquid 
 and washings evaporate to a fourth, add test 3, filter out the pre- 
 cipitate, wash, dry, ignite, and weigh the lime (after deducting the 
 carbonic acid), 1-25. d. The precipitate b. dissolve in test 26, 
 alkalinise with test 1, raise to 212 fifteen minutes, and filter out 
 any spice of iron. e. To the liquid add test 34 ; the precipitate 
 filter out, wash well, evaporate dry, and incandesce the alumine, 
 2'5, or 24. The alkali find by another process. 
 
 (2.) (Lowitz.) Put into a silver crucible powders of car- 
 bonate of potash 50 grains, carbonate of soda 4, and felspar 30 ; 
 while raising the temperature carefully stir to prevent loss by the 
 ebullition ; fuse fifteen minutes ; then add 1 ounce of boiling pure 
 water ; filter out the silica, wash well, incandesce, and weigh. 
 The liquid evaporate much, and find the alumine, etc., as before. 
 
 For the Alkali; the Lithia. In the silver crucible (with a 
 leaden head, and a leaden pipe and receiver adapted for refrigera- 
 tion) put powder of fluor spar 2, and felspar 1 ; the temperature 
 gradually raise, and let the gas evolve, and carry over all silicic 
 acid. In hot water dissolve the sulphate of lithia, and pass the 
 liquid very hot through the filter, on which will remain the 
 alumine and other earths and oxides present. The filtered 
 liquid evaporate dry, and weigh the product. 
 
 The petalite is Al. 3 + Sil. 4 + L. 1 + S. 3 
 = 22*25 ; so that it is a compound of silicate of 
 alumine and silicate of lithia. 
 
270 CHEMISTRY OF POTTERY. 
 
 GTRAUEN (or China Stone}. 
 
 THIS remarkable kind of granite is found only in 
 Cornwall, and mostly in the vicinity of St. Stephens, 
 a few miles from St. Austle. The rock has the 
 three components, small transparent crystals of 
 quartz, disintegrated white and soft common felspar, 
 and small scales of mica, mechanically mixed, and 
 without any spice of metal whatever in the best 
 kinds.* 
 
 The grauen of Cornwall, as likewise the clay 
 from its decomposed masses (hereafter mentioned), 
 were first introduced into the Manufacture by 
 Mr. Cookworthy, a relative of my wife's maternal 
 ancestors. He had closely considered the properties 
 
 * The several kinds of granite have solubility precisely in the 
 ratio of the quantity or proportions and quality of the felspar from 
 plus or minus of lithia ; as this is assisted in its separative potency 
 by the white oxide of iron in the mica, and the carbonic acid of 
 the air, and the oxygen of the water. This is the mean of the 
 components, and also their respective analysis, in 300 grains : 
 
 Quartz. Felspar. Mica. 
 
 Silica 96 64- 48 
 
 Alumine 2 20' 24 
 
 Lime 2 1-75 
 
 Potass _... - 11-5 
 
 Oxide of Iron - -25 15 
 
 Lithia - 14- 
 
 Manganese - 1-5 
 
 100-0 100-00 100-0 
 
THE EARTHS. 271 
 
 of the specimens sent from China by D'Entrecolles, 
 and obtained from Limoges by Reaumur, and while 
 residing at Plymouth he made the needful experi- 
 ments on the grauen, and obtained a patent for its 
 appropriation ; which patent he sold to Mr. Richard 
 Champion, of Bristol, son of the spirited Mr. C. 
 who erected the first laboratory for the reduction 
 of zinc, under a patent, in 1743 as Dr. Ure inci- 
 dentally mentions, Diet. Chem., p. 671, 4th edition. 
 There is some difference in the grauen from 
 different quarries in regard to the precise proportions 
 of the components, quartz, felspar and mica, though 
 always resolvable into the chemical components, 
 silica alumine and alkali. Sometimes the rock 
 resembles an earth, is easily pulverised, and, breathed 
 on, supplies the odour of clay ; in other instances it 
 is undurated, and does easily yield to the action of 
 air and moisture. The crystallised quartz, merely 
 silica with a spice of alumine, varies in its propor- 
 tions, and is not needed in either body or glaze, 
 because its silica can be supplied by flint ; and also, 
 although it is resistive of disintegration by the atmo- 
 sphere, yet every crystalline substance constantly 
 tends on every presented opportunity to resume its 
 crystal form, the momentum of the tendency being 
 varied by the menstruum, quantity, and combinative 
 potency of the elements. The mica likewise varies 
 in its proportions, and much deteriorates the other 
 components, injuring proportionately the ware into 
 whose body it is introduced. Whenever its phos- 
 phoric acid is solicited by sulphuric acid, the combi- 
 nation effects the glaze, and causes it to be without 
 lustre, richness or permanence. The felspar is very 
 
272 CHEMISTRY OF POTTERY. 
 
 well adapted to the purposes of the Art, and espe- 
 cially when these are combined with determined 
 proportions of other components. Hence the differ- 
 ence in the purchased ground-stone, and also in the 
 china clays supplied to the Manufacturers. 
 
 Each of the works has a quarry for the grauen, 
 which is first detached by blasting and wedges, and 
 then broken into pieces of suitable size to be for- 
 warded for the Manufacturer. A little inspection 
 will prove that in this rock much felspar is present 
 in a disintegrated state, not seldom with a slight 
 proportion of magnesite or steatite. The stone thus 
 quarried is not subjected to any further process or 
 preparation prior to being shipped at Charlestown 
 or Portsea.* 
 
 * In Nicholson's Philosophical Journal, vol. viii., pp. 127-131, 
 is Mr. Accum's Analysis of Grauen, which, because the details are 
 curious, I did intend to introduce ; but on examining them I 
 found, and I think so will every other person who understands 
 what he reads, find (that, although I do not mean to charge 
 Mr. A. with excessive modesty in assertion, nor over-scrupulous- 
 ness in conclusions) the results he gives as the components will 
 not accord with those of any of the analysts now acknowledged. 
 He has overlooked the composition of the grauen quartz, felspar 
 and mica ; he has forgotten that lime is ever present in the second, 
 and also with fluoric acid in the last; in exper. xii. he obtains 
 9 grs. of rmiriate of soda, which in xiii. supply him with 4'50 grs. 
 of potash ; and the whole contains, in 100 grs., silica GO'OO, alu- 
 mine 28-00, oxide of iron 0'25, potash 4-50, water 6'00, Loss 1-25- 
 = 100. How Mr. Nicholson overlooked the statement, we need 
 not inquire. 
 
THE EARTHS. 273 
 
 CHINA CLAY. 
 
 WHEN the atmospheric alternations cause the 
 grauen to disintegrate wholly, the felspar crumbles 
 to powder, and the result is the CHINA CLAY an 
 indispensable component of the body of porcelain 
 and best earthenware, because of the entire absence 
 of metallic particles. When properly prepared, 
 usually it has a beautiful and uniform milk white- 
 ness, and breaks readily between the fingers, without 
 grittiness. However soft and white the several kinds 
 may appear, they are not pure alumine, but native 
 neutralised compounds of silicic acid and alumine. 
 That remark of Wedgwood's, that the components 
 are alumine 60, silica 20, and adventitious sub- 
 stances and loss 20, must have been an oversight ; 
 for as the crude grauen has silica 208, alumine 44, 
 lime 4, and alkali 44, in 300, there seems no way 
 by which the atmospheric action can abstract 148 of 
 the chief component silica, and introduce 136 of the 
 alumine, and yet without altering the other compo- 
 nents. The proportions of the porcelain earths of 
 the continent support the view I have taken of the 
 china clay. That of Limoges, used for the porcelain 
 of Sevres, and also exported to Copenhagen for the 
 like purpose, has silica 65, alumine 35 ; that of Passau, 
 used at Vienna, silica 70, alumine 30 ; and that of 
 Aux, used at both Dresden and Berlin, silica 69, 
 alumine 31 ; though H. Rose gives 52 and 47 as 
 the mean of all the kinds. The Chinese porcelain 
 earth, or kaolin, when pure, is friable, meagre to 
 
'274 CHEMISTRY OF POTTERY. 
 
 the touch, scarcely adheres to the tongue, and with 
 difficulty forms a paste with water, and is refractory 
 in the oven. 
 
 The clay, as found native, resembles new-made 
 mortar in colour and general appearance. Many 
 angular fragments dispersed in it prove that it has 
 not been far conveyed. Also reddish-brown irregular 
 stripes, patches and veins occur, and because of the 
 mica present, are separated, as weed, by the work- 
 men. There probably is plenty of the clay in other 
 parts of Cornwall, but the ports of Liverpool and 
 Bristol, and the potteries of Staffordshire and the 
 North, are supplied from several works in a barren 
 district a few miles from St. Austle. 
 
 The clay is found at various depths below the 
 surface from 2 to 20 feet, over which are super- 
 imposed, separated by a waving irregular outline, a 
 bed of light-coloured earth, and over this the vege- 
 table soil. In some beds the clay hold* down 30 feet 
 or more, at Trethosa. Being found in valleys or 
 ravines, it is regarded as having been many ages 
 depositing from the detritus of the grauen by the 
 water from the ground above. The clay is dug in 
 progressive roads, 4 or 5 feet deep, and either cast in 
 a large heap, or immediately conveyed to the spot to 
 be in small heaps on a large scale elutriated. In the 
 vicinity of the works is a stream of water, which 
 is caused to flow over these small heaps, which are 
 frequently turned by mechanical and manual agency. 
 In passing through and over the heap, the water 
 becomes charged with particles of clay, and passes 
 by proper arrangements into tanks of different sizes, 
 provided with plug-boards, like the arks of our 
 
THE EARTHS. 275 
 
 flint-mills. The first is called the mica pit, because in 
 it the most ponderous and useless particles subside ; 
 while the lighter particles are carried away into other 
 tanks, where deposition is carried on further ; and the 
 water from the pits ultimately is received into more 
 capacious tanks, in which only the finest particles 
 deposit. When a certain quantity of deposit is 
 supplied, and the clear water drained away, the 
 clay, like a thick mud, is spread over shallow tanks 
 called pan*, 10 or 14 inches thick, and here it 
 evaporates dry in a few months, the supplies of 
 September being dry in April or May, according to 
 the season and the weather, as also the consistence 
 and thickness of the fluid mass. And probably this 
 long exposure in a moist state renders the clay more 
 fit for the Manufacture, atmospheric changes pro- 
 moting the decomposition of the felspar. The clay 
 is next cut into brick-shaped blocks, which are either 
 removed to a drying-shed, and placed on wooden bars 
 to freely admit the access of air, or on beds of coarse 
 gravel, as opportunity is presented. When quite 
 dry all the coarser particles, and other injurious 
 appendages, are carefully scraped away, and the fine 
 portion is put and pounded into casks, to fill them 
 completely, in which state they are forwarded to 
 their ulterior destination. 
 
 Bleaching Clay. The scrapings of the dried 
 lumps, and the waste of the packing, are washed in 
 a small pit, near the packing-house, and therein 
 remains all the coarser matters, while the overflow 
 runs into one of the large ponds ; whence the water 
 -afterwards is carried away by channels beneath, 
 
 T 2 
 
276 CHEMISTRY OF POTTERY. 
 
 which in some instances lead to shafts communi- 
 cating with mine-adits in the rock beneath. 
 
 The relative extent of the parts varies at different 
 works. The chief and only erections are a shed for 
 the office, a store-room for the casks, etc., in which 
 the clay is packed, and the others, open on three 
 sides, for drying the clay, formed of timber. At 
 one large Work three small streams wash the clay, 
 and pass in succession, each through three pits, 40 
 inches deep, two of them 6 feet square, the other 9 
 feet by 6 feet, the last only supplying the liquid for 
 the nine ponds of various sizes, whence it is laded 
 into sixteen others, for final evaporation. They all 
 are together in a yard. Thirteen persons are here 
 employed ; eight to quarry the clay, at a certain price 
 per cubic fathom, three to forward the washing, and 
 two to attend the ponds, pans, and packing, as each 
 might especially need. 
 
 Dr. T. Thomson gives this series of analyses of 
 kaolin, or porcelain clay. (Mineralogy, p. 200) : 
 
 Eose. Berthier. Thomson. 
 
 Silica 
 
 Alumine 
 
 Alkali 
 
 Magnesia 
 
 Lime 
 
 Oxide of Iron 0-33 ' 1-8 8-5 6-98- 
 
 Water 13-0 7'2 9-5 19-22 
 
 
 1. 
 
 2. 
 
 3. 
 
 4. 
 
 5. 
 
 
 52-00 
 
 46-8 
 
 58-6 
 
 55-8 
 
 63-5 
 
 50- 
 
 37-10 
 
 47-00 
 
 37-3 
 
 34-6 
 
 26-0 
 
 28-0 
 
 25- 
 
 24-48 
 
 
 
 2-5 
 
 2-4 
 
 8-2 
 
 1-0 
 
 2-0 
 
 
 
 
 
 
 
 1-8 
 
 0-5 
 
 8-0 
 
 0-7 
 
 
 
 
 
 
 
 
 
 
 
 
 
 5-5 
 
 9-28 
 
 99-33 99-6 97*4 99-5 100-5 101-4 97-06 
 
THE EARTHS. 277 
 
 1 from St. Yrieix, 2 Meissen, 3 St. Tropez, 
 4 Mende, 5 Normandy. He thinks the kaolin is 
 (4 AL + f.) S. + (Cal. 4- k.) S. ; or, 
 
 Thomson gives these for Arfwerdson and Ginelin : 
 
 Silica 
 
 79-212 
 
 74-17 
 
 Silica 
 
 37-08 
 
 12-6 atoms. 
 
 Alumine 
 
 17-225 
 
 17-41 
 
 Alumine 
 
 7-73 
 
 2-62 
 
 Lithia 
 
 5-761 
 
 5-16 
 
 Lithia 
 
 2-94 
 
 ! 
 
 Lime ' 
 
 
 0-32 
 
 
 
 
 Water 
 
 
 2-17 
 
 
 
 
 102-198 99-23 
 
 We find the atoms of silica (in leetite) rather 
 more than five times as numerous as those of the 
 bases (silica 3975 atoms, alumine 5*42, soda T50, 
 magnesia 0'44, oxide of iron O'lO). If the oxide of 
 Iron be a spice, and we add together the Magnesia 
 and feoda, then the atoms of alumine are nearly 
 thrice the number. 
 
 CHERT. 
 
 THIS mineral is employed in the flint mills, 
 and the supplies are from Derbyshire and the 
 Halken mountain, in North Wales. The components 
 are as hereafter stated ; but the latter is considered 
 as much better adapted for the purpose, because of 
 the greater quantity of lime present in the former 
 kind, and which becomes intermixed with the flint 
 during the abrasion, and in such proportion increases 
 the liability of the body to be injuriously affected by 
 baking. 
 
278 CHEMISTEY OF POTTEEY. 
 
 The lustre of chert is vitreous, inclining to 
 pearly upon the faces of cleavage, in the varieties 
 possessing pale colours. Colour, various shades of 
 green, often inclining to brown, white, and black, 
 with every intermediate shade ; nearly transparent 
 in some varieties, in others opaque ; brittle ; hard- 
 ness about the same with feldspar ; specific gravity 
 2-575, 2-620, 2'600. 
 
 The analyses supplied from three kinds gave 
 these as the mean results : 
 
 Halken. Derbyshire. 
 
 Silex 60-31 58-26 * 62-38 
 
 Alumine 10-26 11-48 12-18 
 
 Lime 13-66 13-96 18-20 
 
 Magnesia 13-04 2-98 O'OO 
 
 Protoxide of iron 0'45 3-43 6-04 
 
 Ditto Manganese 0-25 7'25 O'lO 
 
 Fluoric Acid 0'94 1-60 -06 
 
 Water and Loss .. 1-10 1'04 1-04 
 
 100-00 100-00 100-00 
 
[ .279 ] 
 
 CHAPTER V. 
 
 METALS. 
 
 FROM the earliest period of recorded time 
 METALS have been the favourite subjects of the 
 chemist's investigation, and during a long era know- 
 ledge of their plainest characteristics constituted all 
 implied by the word CHEMISTRY.* And the favour- 
 itism is warranted by their great importance and 
 utility, as well as their intimate connection with the 
 Arts and state of civilised society ; their susceptibility 
 of expansion by the hammer or rollers, of ex- 
 tension as wire, of casting into figures, and some 
 
 * At page 476 of the Transactions of the Imperial Academy of 
 Sciences of St. Petersburg, for 1810, Julius Von Klaproth states, 
 that the cultivation of Chemistry at a very early date by the 
 Chinese is proved by a volume which he describes, written about 
 756 A.D. In this the principle which we name oxygen is called 
 the impure part of the air, and is supposed to be a combination of 
 sulphur, charcoal, and the metals ; that it may be obtained from 
 saltpetre by the application of high temperature, also from the 
 black stone called Hhetann-che, and there are conjectures that it 
 is one of the components of water. Kespecting the metals the 
 notions have great similarity to those of the alchemists. 
 
280 CHEMISTKY OF POTTERY. 
 
 not thus tractile form the bases of the artist's 
 palette. Without bronze or steel for cutting in- 
 struments, how imperfect would be the state of the 
 Arts,' and in similar condition the transactions of 
 commerce without gold or silver as a valuable 
 medium ! 
 
 From remote antiquity have been known these 
 seven Metals Gold, Silver, Copper, Tin, Iron, Lead, 
 and Mercury, with which every European has 
 some acquaintance ; and when first known by tha 
 early societies of mankind, such importance was 
 attached to the advantages of their fabrication into 
 utensils or implements, that mythology assigned 
 among the gods the eternal condition of the first 
 practisers of metallurgical chemistry. Our day, 
 however, witnesses the established existence, beyond 
 the possibility of subsequent researches to annihilate, 
 of six- times zeven, allowing that some are mere 
 curiosities of the laboratory, also for the peculiar 
 evanescence of some, and the imperfect current 
 investigation of others. 
 
 The usual state in which metals are presented is 
 not the natural one, but the artificial result of the 
 manipulations of art, and the igneous processes of the 
 decomposition of their original compound ores. For 
 we find always, on a scale larger or smaller, from 
 circumstances there is some contrivance or other 
 to keep up a supply of oxygen gas to the mineral, 
 which being fixed by the hydrogen evolved by the 
 fuel, its atomic momenta are transferred to the ore 
 which is to be swelled and deoxydated, while any 
 lime present with the ore melts and combines with 
 the argillaceous substance of the matrix. 
 
METALS. 281 
 
 The generality of intelligent miners are of 
 opinion that ORES GROW, and the certain manner 
 of their growth is proved by numerous and con- 
 clusive phenomena. And now that clearer know- 
 ledge of chemical agency is current, we may indulge 
 the opinion, that attention to the several conditions 
 will soon develop the connection between the 
 primary principles, the rocks, the matrices, the 
 mineralisers and the resulting metal. 
 
 Continuous galvanic action and reaction among 
 the rocks of mines or the reciprocal action of the 
 principles of acidity and alkalinity with atmospheric 
 air on the rocks, excited by the constant pressure of 
 that active central force ceaselessly produced by the 
 earth's twofold motions has been demonstrated by 
 experiments made by Mr. Robert Ware Fox, in 
 the mine of Huel Servel, Cornwall. These galvanic 
 momenta must in all instances be regarded as the 
 mere play of oxygen and nitrogen disturbed by 
 different surfaces, and exhibited by the different 
 capability of rocks to conduct the motions of heat 
 and of chemical combination. 
 
 The most usual repositories of ores are those 
 stratified portions of mountainous districts by some 
 powerful subterranean agency convulsed and thrown 
 into dislocated masses. In these masses of rocks, 
 near or remote, were caused fissures, cracks, crevices, 
 ^cavities, and spaces, some almost horizontal, as in 
 extended plains, where exist beds, comparatively 
 level, even though at a considerable depth beneath 
 the surface ; others with varied dip or inclination ; 
 yet often the excavations show that the derangement 
 in the strata has exposed some to the operations of 
 
282 CHEMISTRY OF POTTERY. 
 
 mechanical agency, which but for that would have- 
 been too deeply lodged to have been reached by 
 human art. The fissures in these strata, or fractures, 
 and dislocations, when filled with metallic ores, 
 are called Vein*, and not seldom do they separate 
 and again unite, or disperse into ramifications called 
 strings or threads. The vein is usually tilled with 
 quartz, calcareous spar, clay, or earth, and because 
 these keep the rocks separate from the metallic ore 
 they are called the matrix, gangue, vein-stone, or 
 rider of the ore, which often runs parallel to the 
 strata, though without any regularity of thickness, 
 and sometimes crosses from the one portion of the 
 rock to the other in all directions. When the vein 
 is not tilled up with matrix the crystallised ore lines 
 the cavity. The ore is mineralised, or in a state of 
 combination with sulphur, arsenic, and carbonic acid, 
 the most usual mineralisers, saline compounds ; and 
 though not included amongst them, oxygen as 
 frequently as any, the ores being distinguished as 
 sulphurets, arseniates, carbonates, salts, and oxides. 
 The presence of sulphur is demonstrated by the suf- 
 focating effluvium resulting when lightning strikes 
 a house, but that of arsenic remains a problem to- 
 be solved. From these substances the ores can be 
 separated only by art, though occasionally the metals 
 are exhibited in a native or pure metallic state. 
 
 The confusion of rocks in all metallic mining 
 districts, and the extended knowledge current con- 
 cerning the nature of electric action, suggest this 
 as the most general and probable principle, that all 
 metals are the chemical products of galvanic pheno- 
 mena. And although this would be regulated by 
 
METALS. 283 
 
 the proportion of the electric excitement, yet as the 
 age of the metalliferous strata may be a thousand 
 or more centuries, very small increments annually 
 would account for the greatest quantity known of 
 metals. We are well aware of the facts, yet remain 
 uncertain of the manner, in which the combinative 
 potencies of certain modifications of matter generate 
 varied momenta of heat the principle of galvanic 
 action ; or, the presence of oxygen with other modi- 
 fications form the several substances named acid, 
 alkali, earth, and oxide ; or, the air in the veins 
 of rocks supplies the elements of electric action ; or, 
 the oxygen and hydrogen principles are carried to 
 the surfaces of rocks ; * or, the outer coating of the 
 vein, the matrix of the ore, whether intermixed or 
 alternating in layers with the ore, is of finer grain 
 than the rocks adjacent ; or, the mineralisers by 
 combination deprive metallic substances of their 
 usual characteristics ; but to this plain acknowledg- 
 
 * The alkaline property of metals, and the connection of the 
 principle of alkalinity with hydrogen, have yet to be more clearly 
 explained ; and in the absence of these it will remain matter of 
 conjecture whether or not hydrogen, which constantly solicits and 
 is solicited by oxygen, is essentially metallic that principle of 
 which every kind of metallic substance is merely a modification 
 and the mother-metal sought by the alchemists, which they only 
 required to discover, and develop the application, to have accom- 
 plished their avowed object of transmutation. The race is not yet 
 extinct; for the List of Patents for February, 1836, has this notice : 
 "Lightly Simpson, Manchester, Lancashire, Alchymist; for certain 
 improvements in the preparation of certain colours, etc." The 
 probability, however, is, that Mr. S. is a very clever practitioner 
 of the Art of chemical combination, and desirous to serve society 
 and himself at one and the same time. 
 
"284 CHEMISTRY OF POTTERY. 
 
 ment, as well as to our not having clearly determined 
 other obscure conditions, no more censure will attach 
 than could with propriety be cast on the following 
 truly modest confession of one of the most intelligent 
 metallurgical chemists that has appeared on the 
 stage of philosophical investigation, Professor PROUST, 
 of Madrid. Having been most busily employed in 
 some interesting researches, which he was communi- 
 cating to the Institute at Paris, after particularising 
 various remarkable phenomena, he says: " In an 
 instant the substances begin to grow red at the points 
 where the heat exerts its action. Is it sulphuretted 
 hydrogen which they lose ? For my part, I CANNOT 
 TELL." 
 
 Agreeably to the character of the oxygen and 
 hydrogen principles, during periods of time extended 
 beyond all chronological data, as already hinted, 
 the silent action of undisturbed galvanism, carrying 
 from surface to surface the aura, or finest particles 
 of the rocks, could not fail to produce intermediate 
 substances the matrix, the mineraliser, and the 
 metallic particles in threads or ores, with similarity 
 of crystallisation, and every indication of simulta- 
 neous generation filling the intermediate space 
 with compounds of oxygen, nitrogen, and elements 
 of the rocks, whose distinctive qualities would 
 characterise the condition of the produced ore. 
 
 Metals are much the greater number of the sub- 
 stances which current processes have failed to prove 
 compounds, or decompose. From their general 
 chemical analogies it was conjectured by the early 
 chemists that they all were, in fact, aggregations in 
 varied proportions of a very few elements ; whence 
 
METALS. 285 
 
 originated the idea of Transmutation the attempt 
 to solve the problem of changing metals of less value 
 into others of greater by altering the proportional 
 quantities of their known as well as of their conjec- 
 tured elements.* That metals are such compounds. 
 
 * Perhaps the latest recorded instance of expert juggling in this, 
 mysterious and fallacious art, and proof of the practices of alchemy 
 in the east, even in the present century, is the following, given 
 on the authority of an Englishman of talent and respectability : 
 In 1814, over the English Factory at Bassora Mr. Colquhoun was 
 president, and once received the solicitation of an Arabian philo- 
 sopher for a private interview, to communicate a most important 
 secret. Consent being given, the next morning witnessed the 
 strange and mysterious visitor embracing the president's knees, 
 and supplicating protection from the English against the con- 
 tinued and cruel persecutions of his countrymen, who daily put 
 him to the torture, to wring from him his secret of the method of 
 transmuting the basest metal into gold. He stated that he had 
 just escaped from Grane, where he had been imprisoned and 
 starved by the Sheik, and that on condition of his being per- 
 mitted to reside in the factory he would faithfully divulge the 
 whole of his knowledge of the processes ; and to previously afford 
 a convincing proof of his skill, on Mr. C. expressing a disposition 
 to protect him, he retired for a short time, and then returned to- 
 Mr. C., bringing with him a small crucible and chafing-dish of 
 coals. While the former was acquiring a red heat, he took from 
 his pouch four small papers of a whitish powder, and requested 
 some lead from Mr. C. This gentleman retired to his library, 
 and procured four pistol-balls, whose weight he ascertained 
 unknown to the adept. On these and the powders being pro- 
 jected into the crucible fusion immediately ensued, and after 20 
 minutes the crucible was removed by Mr. C., and when cold, the 
 button in the bottom proved to be of pure gold, and the like 
 weight as the bullets, and in the bazaar was valued at 90 piastres. 
 How the deception was effected as after the Arab placed the 
 crucible on the coals only Mr. C. touched it o-r why a poor 
 Arab should present an Englishman with 90 piastres, cannot be 
 
"286 CHEMISTKY OF POTTERY. 
 
 will seem extremely probable, on the following 
 account : those which are inflammable assuredly 
 must have hydrogen present ; whatever inflames 
 cannot be an element ; tor this phenomenon proves 
 that hydrogen evolves, and combining with oxygen 
 causes burning ; therefore, whether or not directly 
 exhibited, there must be present hydrogen, oxygen, 
 and some base, although this last had not yet been 
 developed. All metals by heat vitrify, and vitrifi- 
 cation is attributed to silica ; hence the probability 
 that silica is also present with such base. In the 
 fracture of iron-stone no metallic particles are 
 visible ; it therefore is no less rational to regard the 
 metal as formed of primitive atoms, even though we 
 are ignorant of their nature, than that it is an oxide 
 of what never existed in a native state to be oxi- 
 dated. Yet, as they remain undecom posed by the 
 solicitings of the most powerful agents, their change,, 
 one into another, is a problem whose solution by 
 any train of reasoning is entirely hopeless, and by 
 accident alone will it be developed. 
 
 An extended and better acquaintance with com- 
 binative potency proves that Davy's decomposition 
 of the alkaline oxides is a mere excitement, 
 promoted and facilitated by the oxygen of the 
 positive pole and the nitrogen of the negative ; the 
 
 easily determined. However, his return next morning, to enjoy 
 the protection of the factory, agreeably to Mr. C.'s arrangement, 
 was prevented by the Shiek of Grane's armed bands entering 
 the Arab's house during the night, carrying him away, and 
 putting him on board a boat, which was out of sight long before 
 daylight. 
 
METALS. 287 
 
 disturbance of the former by mere reaction carrying 
 the metal to the negative pole, the oxygen being 
 expelled from the oxides by the atomic momenta 
 and double action of the galvanic poles, on the same 
 principle, that to produce our puritied and artificial 
 metals we dissipate the oxygen and nitrogen, dis- 
 perse the heterogeneous substances, and melt the 
 rocky materials. But the supply of momenta being 
 only temporary and dispersive, and the alkaline base 
 not being adapted for our oxidated atmosphere, 
 whenever opportunity offers the supply is re-ab- 
 sorbed, and the patient becomes an oxide capable 
 again of enduring the atmosphere. 
 
 The imperfection of current processes precludes 
 the determination whether, or how far, metals in 
 their metallic state reciprocally solicit each other, 
 and thereby so alter some of their peculiarities as to 
 prevent the usual methods detecting the presence of 
 one or more of them. But if such momenta really 
 exist, and combine substances, two or several, and so 
 blend their properties that together they seem only 
 one, whenever they have fully operated, the sepa- 
 tion into elements will not be an easy task ; and 
 more particularly when none of the substances are 
 distinguished for great combinative potency with 
 others. The solution of the problem is an object of 
 much importance, and will be regarded as of com- 
 prehensive interest, because it involves a controversy 
 concerning the existence of several substances with 
 which our present imperfect knowledge overburdens 
 us, and compels us to regard as simple, and dignify 
 with the distinction of elements. 
 
 Of the importance of these discoveries, in 
 
288 CHEMISTRY OF POTTERY. 
 
 reference to the chemical nature of substances, especi- 
 ally of the metals, no doubt will be entertained,. 
 I think, by any reflecting person. And that we are 
 on the eve of yet more interesting developments 
 will be readily admitted by every person who con- 
 siders the annexed details. In the autumn of 1835 
 the Academy of Sciences at Paris announced that 
 M. Becquerel has supplied an electro-chemical 
 apparatus of iron, with which, and a concentrated 
 solution of common salt, also the mineral properly 
 prepared, he has effected the immediate reduction of 
 silver, lead, and copper in a crystalline form, and 
 in a regular succession, but with varied facility, 
 because of their different degrees of oxidation, and of 
 the compounds generated during their deoxidation. 
 M. Aim6 has improved the apparatus. An open 
 tube of iron is bent in the form of U ; the outer 
 portion at the bottom of the bend is pierced with a 
 small hole, into which is loosely put a little asbestos. 
 The legs are half-filled with fine, well-washed sand,, 
 and afterwards one is filled with dilute sulphuric^ 
 acid, and the other with a concentrated solution of 
 sea-salt (in such a state of non-equivalence, however, 
 as will preclude the formation, on their combining, 
 of a salt, which would obstruct the discharge), alsa 
 by arrangements for a supply regulated by the pro- 
 portionate discharge after their combination, thereby 
 securing an indefinite continuance of the decomposing 
 process, varied in its intensity by the concentration 
 of the solutions, and the facility of the combination 
 consequent on the size of the orifice for the dis- 
 charge. The two fluids permeate the sand, and 
 combine at the lower part of the tube, forming a 
 
METALS. 289 
 
 fluid which escapes through the hole. Into each leg 
 dips a platinum slip, from each of which extends a 
 wire to a galvanometer. On forming the circuit by 
 contact, the change of direction of the needle indi- 
 cates the formation of the momenta resulting from 
 the reciprocal action of the fluids. 
 
 Reasoning from the phenomena of potassium, 
 sodium, lithium, barium, strontium, calcium, and 
 magnesium (the metals obtained by galvanic reduc- 
 tion of their oxides, potash, soda, lithia, barytes, 
 strontia, lime and magnesia), metals are alkalies, 
 combined with sufficient oxygen, not to neutralise 
 the alkaline bases, but to protect them, and counter- 
 act the prevalent tendency to become oxides in the 
 ordinary state of the atmosphere. Like sufficiency 
 of oxygen, in varied degrees, affects other metals ; 
 but it is obvious that all of them equally consist of 
 oxygen and an alkaline base, not yet known defini- 
 tively as simple or compounded, though the varied 
 colours of the oxides, and their re-active potencies, 
 imply some combination with the alkali. These 
 six metals aluminum, glucinum, cerium, yttrium, 
 zirconium and thorium, are formed by abstracting 
 oxygen from their earths (which as pure oxides are 
 white inodourous powders), and which seem pro- 
 bably compounds of carbon with other elements. 
 
 With the exception of two or three metals- 
 harder than the others probably from excess of a 
 silicious base over the alkali combined during their 
 electrical generation all the metals, from the 
 evanescent potassium to the one most fixed, 
 agreeably to the variety of their components, have 
 every degree of tendency to abstract the oxygen 
 
 u 
 
290 CHEMISTRY OF POTTP:RY. 
 
 of the air, and, as oxides, return to their original 
 state. 
 
 The Metals possess the following general CHAR- 
 ACTERISTICS : 1. A peculiar lustre, continued in the 
 fractured streak and smallest fragments. 2. Fusi- 
 bility by heat, and while fused retaining their lustre 
 and opacity. 3. Ready concentration of the motions 
 of heat, and of oxygen separated from hydrogen 
 by the electric machine and the galvanic circuit. 4. 
 Being malleable, laminable, and ductile, extending 
 under the hammer, by the rolling-press, or through 
 the wire-mill ; the susceptibility resulting from a 
 tenacity peculiar to each kind, yet different in 
 degree. 5. Brilliance and opacity, reflecting most 
 of the rays of light which fall on their surface ; 
 hence forming excellent mirrors. 6. When in 
 fusion susceptible of combining with each other, 
 in metallic alloys, in determined proportions, yet 
 preserving peculiar lustre and tenacity. 7. In the 
 galvanic circuit their saline compounds are decom- 
 posed, the negative pole soliciting the respective 
 metals. 8. At a high temperature, in presence 
 of oxygen, chlorine, and iodine, most of them 
 inflame ; and, combining with one or other of the 
 three in determined proportions, they form bodies 
 devoid of ductility and lustre, but saline-looking 
 or earthy, termed oxides chlorides, and iodides. 
 9. Most of them combine, in determined proportions, 
 with sulphur and phosphorus, forming semi-me- 
 tallic compounds. Others, to form .peculiar gaseous 
 or solid compounds, combine with hydrogen, carbon, 
 and boron. 10. Many of them, by certain processes, 
 crystallise mostly in cubes or octahedrons. 
 
291 
 
 Hydrioda 
 of Zinc. 
 
 y 
 
 .S 
 
 > 
 
 I 1 
 
 " 
 
 s i 
 s 1 
 5- 
 
 
 oa copq>i>?QcSS 
 
 Hydro- 
 lphuret 
 
 ^ -7 : j 
 
 ^ 
 
 cqeqaqcq 03 
 
 * 
 
 > O 
 
 I 
 
 CO 
 
 of Galls 
 
 LO 
 
 Gall 
 
 .11.1 1 
 
 : I " i ^ " 
 
 r * "&P 
 
 g c cjs o 
 -3 S2 i 
 
 C5 > OP5 SU 
 
 aj 
 255.2.2 
 
 a c 
 S S 
 
 O O 
 
 111 
 
 ocyanate p 
 of Potash 
 
 | 
 
 S.S 
 
 i 
 
 i 
 
 i 
 
 
 
 ll 
 
 
 f 
 
 b S!5 
 
 ill-- 
 
 
 Sss-^ 
 
 a .=2 
 
 
 * 'poo.n 
 
 pq pqasaqaq PQ 
 
292 CHEMISTRY OF POTTERY. 
 
 RECIPROCAL COMBINATIVE POTENCIES OF THE METALS. 
 
 The investigation of the conditions under which 
 the metallic oxides reciprocally solicit each other 
 is alike peculiarly interesting and important, inas- 
 much as it involves, directly or indirectly, the whole 
 theory of enamel colours, coloured glazes, and 
 coloured dry bodies. And, separate from this Art, 
 it likewise regards that of metalline pigments, and 
 numerous particulars in General Chemistry. The 
 activity of philosophical inquirers has not yet suc- 
 ceeded in removing all the obscurities and develop- 
 ing all the peculiarities of the subject, and probably 
 the very complex results cause the paucity of current 
 information concerning them. 
 
 Essential conditions of the problem are, the 
 reciprocal action, the momenta and consequent 
 oxidation, also the different potency of each metallic 
 oxide to solicit and neutralise the respective acids. 
 
 By clearly developing the succession in which 
 metalline solutions precipitate oxides, there will 
 be simplified one part of analysis, as well as the 
 purification of the metallic salts. The illustrations 
 annexed will probably remove much of the obscurity 
 and complexity which have involved this subject 
 to the present time. I cannot help thinking, that 
 if from the whole of the facts detailed there can 
 be discovered any necessary and direct connection 
 between the results of the analysis and the practical 
 fabrications between the principles developed by 
 the one, and the effects supplied by the other most 
 of the doubts would be removed, most of the diffi- 
 culties overcome, the obscurities illustrated, and 
 
METALS. 293 
 
 theory conjoined with experience would lead to a 
 complete solution of the problem. 
 
 Each metal, and even each different oxide of 
 the same metal, to oxidise needs a certain and 
 peculiar temperature. Lead at one temperature is 
 minium, at another massicot. Oxidation ensues 
 when the reaction of the potency of the metal and 
 that of oxygen exceed those of concentrated oxygen 
 present in the galvanic circuit ; and only does it 
 ensue from fusion when the potencies exceed those 
 of atmospheric pressure which cause cohesion. It 
 also ensues on disturbing the potencies of a com- 
 pound of oxygen and some base. The degrees are 
 constant and determinable specially by the pro- 
 perties of the salts formed, whose colours do not 
 always indicate their metallic base, and which salts 
 are usually neutral, neither aciduline nor alkaline. 
 These degrees are designated by the colour name for 
 common use, and by suitable prefixes for the scien- 
 tific ; thus we say either the black or red oxide of 
 iron, the prot, deut, trit oxides of gold, the per- 
 oxide of tin, for the first, second, third, greatest or 
 maximum state of oxidation, and hydrate when 
 water is present in even a minute proportion. 
 
 The presence of dry air, as well as of the atmo- 
 sphere at usual temperature, will readily oxidise 
 arsenic, manganese, and the metals developed by 
 Davy, but only sluggishly and when previously 
 moistened does the air oxidise copper and lead. 
 At high temperatures, iron, zinc, copper, tin, silver, 
 gold, etc. oxidise in distinctly coloured products. 
 
 Each metal in its pure metallic state is indif- 
 ferent to the soliciting of any acid, and receptive 
 
294 CHEMISTRY OF POTTERY. 
 
 of the potencies of only the non-metallic elements, 
 oxygen, chlorine, carbon, sulphur, phosphorus, hydro- 
 gen, iodine, and bromine, because of which they 
 unite with compounds. The different proportions 
 solicited by the same metal are few, definite, and 
 ever analogous ; the several results differ only in 
 the multiple proportion present in the minimum 
 to the maximum. 
 
 The acids have greatest potency, then the alkalies, 
 and afterwards water, in soliciting metallic substances 
 to combine with oxygen. When a metal is solicited, 
 only can oxygen be supplied by the water present 
 and in contact ; in the alkaline liquid the hydrogen 
 evolves, the oxygen solicits the metal, and the fresh 
 oxide (like one exhibited) is solicited by the potency 
 of the alkaline liquid. When exposure to the air 
 supplies an additional dose of oxygen, the resulting 
 oxide differs from the prior one, and is precipitated 
 with a portion of the acid, precisely that quantity 
 supplied, and therefore not decomposed. Iron and 
 manganese supply instances. 
 
 The presence of water with manganese, iron, 
 zinc, uranium, nickel, cobalt, etc., will supply oxygen 
 for the oxide to have the maximum, like as would 
 result from acids, or the minimum from the acidu- 
 line solution. Indeed only when water is added to 
 concentrated sulphuric or muriatic acid, and after 
 hydrogen gas has evolved with more or less effer- 
 vescence, will iron or zinc oxidise and become 
 soluble in the liquid. The strong combinative 
 potencies reciprocally of the oxygen and sulphur 
 prevent the result until additional oxygen is supplied 
 by the water, and the equilibrium is disturbed. The 
 
METALS. 295 
 
 weaker these potencies are, the more will be obvious 
 those of the oxygen in soliciting the metal. If we 
 substitute for the metallic iron its peroxide, no gas 
 will evolve during the solution ; and because of the 
 weakness of these potencies in nitric acid is its read}' 
 and energetic soliciting of iron and zinc. 
 
 In proportion to the doses of oxygen (or 
 chlorine, etc.) present in the metallic salt, or of the 
 acid in the neutral salt, does water solicit these 
 products to combination, and least does it solicit 
 those with the minimum ; but its solicitings are 
 always in definite proportions, multiplies of the mini- 
 mum. When the result has a quantity of water 
 equal to that of the basic salt, or oxide, the hydrate 
 has more potency than when only in the quantity 
 supplied by the acid. This is another proof of the 
 use of dilute acids. The hydrate of each common 
 metal precipitates when the oxide dissolved in 
 sulphuric, nitric or muriatic acid is solicited by the 
 proper alkali (potash, soda, or ammonia) ; to obtain 
 this as an hydrate, not an oxide, filter out and 
 dry at about 100 Fahrenheit. Ignition dissipates 
 the water of the earthy hydrates ; but those of 
 potash, soda, lithia, barytes, strontia and lime 
 require it to be intense, or else to be accompanied 
 by some potencies with momenta greater than their's 
 towards the water. On water soliciting a metallic 
 chloride, as the chlorine combines with the hydro- 
 gen, muriatic acid results, saturated with the oxide 
 formed by the oxygen liberated from the decomposed 
 water. 
 
 The paucity of positive information on these 
 subjects caused the opinion that, by instituting a 
 
296 CHEMISTRY OF POTTERY. 
 
 series of experiments, I should attempt a task of 
 some utility, and which would contribute to augment 
 and improve our knowledge. The philosophic 
 inquirer never feels humbled at correcting or 
 extending his stores ; nor will he wholly disbelieve 
 a fact, because not in unison with his received 
 opinions, or one to which he cannot adduce some 
 parallel instance. Else he would insurmountably 
 oppose the progress of science, by substituting his 
 own feelings in place of Nature, and by attempting 
 to measure what is immeasurable by the limited 
 scale of human comprehension. 
 
 Mix a little of a solution of red sulphate of iron 
 with much of one of green sulphate ; add test 1, 
 equivalent to the red ; agitate well ; the first supply 
 of the test causes a precipitate of peroxide entirely 
 free from protoxide, but the additional supplies 
 precipitate both oxides together. These precipitates 
 filter out ; and the filtered liquid shows the entire 
 absence of oxide of iron, by being limpid, and not 
 rendered blue by test 9, nor black by tincture of 
 galls. By reversing the process, adding little of the 
 green to much of the red, and adding test 1, all the 
 peroxide precipitated first, and afterwards the 
 protoxide. Therefore, as the protoxide of iron 
 precipitates the red, we easily can prepare green 
 solutions without any peroxide. 
 
 Consistent with the principles of mechanics, 
 as action and quiescence are always equal and 
 opposed in compound engines, only when the ele- 
 ments combine properly in definite proportions has 
 the compound efficient combinative potency. When 
 any precipitant solicits to combination the oxygen 
 
METALS. 297 
 
 of the metal precipitated, the reciprocal momenta 
 of the two metallic oxides towards the acid promote 
 combination in a degree inferior to the potency of 
 the oxygen. Hence the precipitate usually is 
 spiced with the precipitant. Caustic alkali added 
 to a metallic solution usually spices the oxide pre- 
 cipitated, and occasionally dissolves it, Carbonated 
 alkali thus employed precipitates the oxide as a 
 metallic carbonate. 
 
 The sulphate of zinc of commerce frequently 
 has iron present (the true cause of difference in 
 the tint of mat blue). To a solution of sulphate of 
 zinc add test 1, agitate well, and heat to 180 
 Fahrenheit, which will cause to precipitate oxide 
 of zinc and a little peroxide of iron. Test 9 will by^ 
 a blue tint show the presence of protoxide of iron. 
 The liquid divide into two portions, and acidulate 
 one with nitric acid, and boil 15 minutes, and the 
 other with muriatic acid ; to each add test 1 ; the 
 iron precipitates, leaving a solution of pure sulphate 
 of zinc, with a spice of sulphate of potash. Oxide of 
 zinc precipitates peroxide of iron, and is precipitated 
 by the protoxide. The combinative potency of nitric- 
 acid with zinc leaves free much of the peroxide of 
 iron, which precipitates, and what remains has 
 excess of acid, and is separated by exhibiting more 
 zinc. But when the solution has been slowly made, 
 much of the iron is strongly retained, because 
 protoxide. 
 
 Frequently is a metal oxidised by the exhibi- 
 tion of its oxide, and likewise by that of an acidu- 
 line solution of the oxide, because of the acid's 
 varied combinative potency with different oxides, 
 
298 CHEMISTRY OF POTTERY. 
 
 even though much exceeded by that of oxygen. 
 The peroxide of a metal being more potent, and 
 requiring acid equivalent for each salt with the 
 oxygen of the oxides. In the neutral salts the 
 distinctive potency of the components is scarcely 
 recognised. But when to one portion of such salt 
 another portion of one component is exhibited, a 
 compound results whose potencies are completely 
 different. The tartrate and bi-tartrate of potash are 
 good instances. In all these and similar experi- 
 ments, according to the alkali exhibited, the one 
 or two oxides will precipitate, but to render the 
 phenomena more obvious, carefully drop in the 
 test, to precipitate one oxide, and pour it in to 
 obtain both. 
 
 By almost similar processes I noticed that the 
 peroxide of iron is precipitated by deutoxide of 
 copper, yet this is precipitated by the protoxide. 
 Hereby we can readily separate all the iron from a 
 solution of copper, and all the copper from a solu- 
 tion of sulphate of iron. This will suggest a remedy 
 for the altered tints of those colours prepared from 
 sulphate of copper, and where iron has spiced the 
 salt, and not been completely separated. When, to 
 accomplish this separation, the peroxide of iron is 
 formed by nitric or muriatic acid, add test 1, 
 agitate, and at the temperature of 180 will 
 precipitate all the sulphate of iron. 
 
 In the Arts also is often used green sulphate of 
 iron, which should not be spiced with copper. Iron 
 separates it only imperfectly, and after long repose. 
 To the solution of green sulphate of iron add test 1 ; 
 agitate the liquid ; the protoxide rapidly precipitates 
 
METALS. 299 
 
 in company with the deutoxide of copper, leaving in 
 solution whatever peroxide may be present. When 
 the liquid is alkalinised with test 2, to precipitate the 
 deutoxide of copper, rapidly is the protoxide of iron 
 dissolved, though in like circumstances this test 2 
 does not dissolve the peroxide. Exposure to the air 
 separates the solution, ammonia evolves, and a black 
 pellicle on the surface soon precludes further atmo- 
 spheric action. In analysis test 2 is useful to pre- 
 cipitate peroxide of iron when present with nickel. 
 In an aciduline solution the perchloride of mercury 
 quickly precipitates the peroxide of iron, and the 
 oxides of zinc and copper. And in any aciduline 
 liquid suspected to contain metalline particles, by a 
 thread suspend a needle 24 hours, and around it will 
 be precipitated whatever metal is present. 
 
 A nitric solution of silver frequently has a blue 
 tint because of the presence of copper. Add test 
 1, and there is a flocculent precipitate, chiefly of oxide 
 of silver, where the test passed, which gradually 
 solicits deutoxide of copper. Agitate the liquid, 
 the oxide of silver will quickly be re-dissolved, and 
 for it will be substituted the precipitate of copper. 
 Alkalinise the filtered liquid with test 1, an insoluble 
 precipitate results of oxide of silver, which when 
 filtered out leaves the liquid colourless, and entirely 
 free from copper. To supersede this exhibition of 
 potash, separately precipitate, filter out, and wash 
 well a part of the impure nitrate of silver, which 
 again exhibit to separate the remaining portion of 
 copper. This suggests a remedy for some failures 
 in preparing purple. The oxide of silver will 
 separate the nitrate of zinc in the analysis of 
 
300 CHEMISTRY OF POTTERY. 
 
 mat blue, and the oxide of manganese will separate 
 the muriate of copper present in the gold solution for 
 purple. 
 
 The precipitates must not be supposed pure 
 oxides ; the copper is always bluish -green, varying 
 with the other oxides, indicating the presence of 
 some acid. 
 
 The instances adduced are not numerous, neither 
 are they sufficient to explain all, yet their considera- 
 tion will develop some of the conditions of the 
 problem : 1. There is a nearer approximation to 
 equilibrium in momentum to render inert the potency 
 of the acids between the protoxide of iron and the 
 peroxide of mercury, which precipitates the peroxide 
 of iron, the oxide of zinc, and the deutoxide of 
 copper, than there is between any of the latter 
 mentioned. 2. Likewise, for the same purpose, 
 between the oxides of zinc and manganese, which 
 precipitate the deutoxide of copper, and between 
 either and the copper. 3. For the like purpose there 
 is greater potency in the oxide of silver than in that 
 of zinc, or of copper, which by it are precipitated. 
 
 In numerous instances we find the components 
 of a saturated compound possess weaker combinative 
 potency reciprocally than when one is present in 
 a different proportion. But in every instance the 
 potencies of the earths and metals render ineffectual 
 all attempts for their volatilisation. There usually is 
 present with the natural oxides much earthy matter, 
 which being vitrified by the heat exerts consider- 
 able potency to retain the oxide in the vitreous mass ; 
 and this more especially when the ores rapidly sus- 
 tain a short contact with the motions of heat, in 
 
METALS. 301 
 
 which instances, instead of a regulm of the metal 
 (or a button of the metal, to which the term was. 
 given by the alchemists, as supposing it to contain a 
 spice of gold, the king of metals), there results a fine 
 coloured glass or paste. 
 
 This combinative potency of oxygen with the 
 metals causes the employment of substances capable 
 of fixing the oxygen, and receiving any portion 
 evolved, which otherwise would be ineffectual during 
 the application of the motions of heat. When car- 
 bonaceous materials are employed^ and the metallic 
 oxide is free from the solicitings of other substances, 
 the metallic particles leave the added substance, and 
 because of its greater fusibility, they precipitate 
 to the bottom of the crucible, free alike from the 
 oxygen and any acid present, although in combina- 
 tion with the alkali and earth of the flux they form 
 one agglutinated mass of metal. 
 
 Many of the metals can, with great care only^ 
 be by fusion combined into permanent compounds, 
 or alloys, always in determined proportions, possess- 
 ing peculiar qualities, and adapted for only certain 
 uses ; much altered in their fusibility and volatility ; 
 frequently more susceptible to the solicitings of 
 oxygen ; their hardness and colour different from 
 those of either component alone, and the specific 
 gravity rarely the mean of those of the components,, 
 but less usually, and in a few instances greater than 
 the mean. 
 
 Each metal affected by chlorine gas (always in 
 either 9 or 18 multiples of 4) during the subjection 
 to the motions of heat has the oxygen present in the 
 oxide, superseded, and chlorine occupies its place in 
 
302 CHEMISTRY OF POTTERY. 
 
 either one or two proportions in the fresh compound. 
 Of the facts of this combination we have no doubt 
 whatever, though we do not always know the precise 
 proportion. We likewise know that the potencies of 
 cyanogen for metals are very strong, but for oxides 
 very weak ; the water present supplies hydrogen to 
 form hydrocyanic acid while the oxygen solicits the 
 metal. 
 
 Several metallic oxides precipitate alumine in 
 aciduline solutions, because of greater momenta to 
 render inert the potency of the acids. Glucine 
 separates the salts of alumine ; and its solutions, 
 though not completely neutral, are more so than 
 those of alumine. Both these, however, and also 
 most metallic oxides, magnesia precipitates in acidu- 
 line solutions, and completely renders inert the acids. 
 
 A principal cause of the separation of bases in 
 solutions is not the metal's susceptibility to the 
 solicitings of oxygen, but its state of oxidation 
 causing difference of momentum of combinative 
 potency with the several acids. Thus several metals 
 precipitate the peroxide of iron, yet are by the 
 protoxide precipitated. Also several oxides with 
 less oxygen present than there is in the oxide of 
 zinc precipitate it, and yet zinc precipitates others 
 under like circumstances. The protoxide of iron 
 more potently than the peroxide solicits to com- 
 bination muriatic acid, which may be the real cause 
 of the former oxide precipitating the latter. 
 
 On exhibiting an alkali the precipitate retains 
 some of the acid which promotes its solubility ; 
 because of this an oxide with much acid present 
 more readilv dissolves than one with less. The iron 
 
METALS. 303 
 
 precipitated from the red retains less acid than 
 that from the solution of green sulphate, and this 
 precipitate sooner dissolves than the other. 
 
 The ready solubility assists, but does not deter- 
 mine the mutual precipitations of the metallic 
 oxides. The aciduline oxide of copper is precipi- 
 tated by the neutral oxide of silver on adding test 1 
 to a mixture of their nitric solutions. Whenever the 
 addition of another substance changes the condition 
 of the menstruum, or by combining with the metal 
 present renders it too ponderous longer to remain 
 suspended, these will of necessity be a partial or 
 entire precipitation. 
 
 In addition to those which economy requires, 
 there are to be determined and satisfied other condi- 
 tions, indispensable to the complete success of the 
 process, by which are much diminished the number 
 of chemical agents. The minute investigation of any 
 substance individually, to be properly understood 
 in all its peculiarities, requires so much time and 
 patience as seldom to be a sufficient inducement to 
 such an operose undertaking, and only is it pursued 
 because of its being some way connected with other 
 useful collateral subjects. In proportion to the 
 novelty and importance of these interesting results 
 do they require to be confirmed by the experiments 
 of others. And whenever among results there is a 
 difference, new inquiries are indispensable to detect 
 the sources of the difference, and correct or remove 
 all remaining errors. 
 
 The momentum differs in nickel and cobalt ; 
 hence that which most solicits the same acid will 
 precipitate the other, and remain alone in the 
 
304 CHEMISTRY OF POTTERY. 
 
 aciduline solution. Glucine more potently than the 
 peroxide of iron solicits the acids ; hence to separate 
 the iron we need only to effect its condition ; that 
 is, precipitate, filter out, and wash well one portion, 
 and employ it to precipitate the remaining iron. 
 And all the conditions being similar, those sub- 
 stances with greater momenta may cause the pre- 
 cipitation of those with less, when soliciting the 
 acids. 
 
 Although, therefore, we may not know all the 
 conditions of this mutual precipitation, we are certain 
 that one is the difference of momentum of combina- 
 tive potency. Because of this we can free : 1. A 
 solution of protoxide from any peroxide of iron. 
 2. A solution of sulphate of zinc or of copper from 
 any oxide of iron. 3. A solution of green sulphate 
 of iron from copper. 4. A solution of silver from 
 copper ; and indefinitely with the number of the 
 substances employed. 
 
 In this important Art of Life is employed a 
 larger or smaller quantity of each of the metals 
 Antimony, Arsenic, Bismuth, Chromium, Cobalt,. 
 Copper, Gold, Iron, Manganese, Mercury, Lead, 
 Nickel, Platinum, Silver, Tin, and Zinc. 
 
METALS. 305 
 
 ANTIMONY. 
 
 WE have the authority of Pliny (lib. xxxin., 
 c. 6) for the opinion, that the ancients had some 
 knowledge concerning the oxide of antimony found 
 in the ore of silver, now particularly named from 
 its presence ; and there is some probability that they 
 likewise knew of its existence as a bluish-grey 
 mineral, with metallic lustre, which as a sulphuret 
 occurs in nature, and also now from the eighth 
 century called antimony. With this mineral the 
 Asiatics and Grecians coloured their eyebrows 
 black. When Basil Valentine had discovered and 
 promulgated the process of extracting the metal 
 from the ore, it was named, for reasons already 
 mentioned, regulus of antimony.* 
 
 The ore of antimony is usually found in imper- 
 fect octahedral crystals, and thereby is readily distin- 
 guished from all other minerals with which it might 
 be confounded because of colour, fracture, hardness, 
 
 * This Basil Valentine was a monk of Erfurth, in Germany, 
 and was a noted alchemist. Tradition states that having cast 
 away some refuse of the mineral, some hogs took portions of it 
 accidentally ; it purged them violently, but afterwards they rapidly 
 became very fat. His brother monks, by mortification, fasting, 
 and long prayers, being extremely thin, Basil supposed that a 
 like effect to that produced on the hogs would result from a dose 
 of the mineral ; he was, however, much mistaken ; instead of 
 growing fat, soon they died ; and the substance which was so 
 useful in promoting the health of hogs was the contrary to monks, 
 and because of killing them was called anti moine. 
 
 X 
 
306 CHEMISTRY OF POTTERY. 
 
 and weight. Subjected to the blow-pipe flame it 
 readily fuses, and afterwards volatilises in the state 
 of a grey inodourous vapour (unless when spiced with 
 arsenic) ; and when the assay has slowly cooled, it is 
 covered with white, brilliant, acicular crystals. 
 
 Antimony, in its metallic state, has a greyish- 
 white colour, with some brilliance ; the texture 
 laminated, the laminae crossing each other in every 
 direction. Its lustre diminishes, but no other 
 changes ensue from the presence of atmospheric 
 air or immersion under water ; yet a current of 
 steam directed over the incandescent metal so 
 powerfully affects it as to cause violent detonation. 
 When raised to the temperature of 810 it melts ; 
 and by additional rise in an open vessel it gradually 
 solicits the oxygen of the atmosphere, and in a 
 white vapour sublimes, forming what are called the 
 argentine flowers of antimony the protoxide, and 
 the same peroxide when raised to a white heat and 
 suddenly agitated. It crystallises in oblong figures 
 perpendicular to the interior surface of the con- 
 taining vessel, causing its texture to be laminated. 
 When rubbed on the finger there evolve a very 
 peculiar odour and savour ; and on charcoal, in the 
 blow-pipe flame, there is great brilliance, accom- 
 panied with a dense yellow smoke of oxide. It has 
 almost like hardness with gold ; its specific gravity 
 is 6702 ; it is extremely brittle, pulverulent in a 
 mortar, and has a tenacity that capacitates a rod 
 one-tenth of an inch in diameter to support about 
 10 Ibs. weight. 
 
 The protoxide, composed of two doses of base to 
 one of oxygen (A 22 + O 4 = = 26), is of a dirty 
 
METALS. 307 
 
 white colour, devoid of lustre. It can be obtained 
 by this process : The metal treat with test 26 till it 
 is completely separated, and to the liquid add pure 
 water until all precipitation ceases. This precipitate 
 is a submuriate of antimony ; filter out, wash well, 
 dry, and then boil in test 3 ; again filter out, wash 
 well, and dry on the filter. When this precipitate is 
 raised to incandescence it melts, and in a retort 
 can be kept fused a long time, but exposed to the 
 atmosphere it ignites, solicits oxygen, and is con- 
 verted into the deutoxide (A 4 + O 3, or 44 + 12 = 
 56), or antimonious acid (glass of antimony}. 
 
 The most plentiful supply is from the Huel 
 Boys, Endellion, Cornwall, and Saltash, near Ply- 
 mouth ; and also from near Presburg and Puy de 
 Dome. 
 
 x 2 
 
308 CHEMISTEY OF POTTEEY. 
 
 ARSENIC. 
 
 ARSENIC (the white oxide of commerce, the 
 arsenious acid of analytical chemists), is semi-trans- 
 parent, brittle, faintly sweetish, without odour, 
 volatilises at 380 Fahrenheit, and in a quick rise 
 of temperature vitrifies. It is a violent poison in 
 vapour, or applied to a wound, or taken into the 
 stomach. It is sparingly soluble in water, and 
 readily combines with the alkalies. It alloys cobalt, 
 antimony, tin, copper, lead, and some other metals, 
 rendering them brittle compared with their condition 
 when arsenic is not present. The mineral kingdom 
 plentifully supplies it in masses, black, ponderous, 
 slightly brilliant ; and also in two native sulphurets, 
 distinguished by their colours, the yellow sulphuret, 
 orpiment, lemon or greenish-yellow ; and the red 
 sulphuret, of a ruby red tint, realgar, more trans- 
 parent than the former ; and they are produced 
 artificially by dissolving white arsenic in test 26 
 and precipitating by test 13, and by incandescing 
 white arsenic with sulphur. 
 
 It is employed in some glazes to advantage ; 
 because while as a flux it promotes the fusibility of 
 the components, its ready volatilisation capacitates it 
 to dissipate and carry away any carbonaceous matter 
 present in the alkali employed. 
 
METALS. 309 
 
 CHROMIUM. 
 
 DURING about thirty years, or from 1798, when 
 the native mineral, chr ornate of iron (a compound 
 of 1 atom of chromite of iron + 1 atom of chromite 
 of alumine), was first introduced to the attention 
 of chemists, concerning its nature there was great 
 difference of opinion, up to 1820. The mineral 
 having gained the attention of Vauquelin, and been 
 found in serpentine rocks in different parts of the 
 old and new continents, and some of the Shetland 
 Isles, the researches of different analysts have been 
 rewarded with the results of a peculiar acid com- 
 bined with basic iron. This acid reduced with 
 charcoal has supplied a metal, which, however, has 
 not been employed as such in the Arts. 
 
 Chromium has a white colour, intermediate 
 between those of tin and steel ; its specific gravity 
 5 '90, extremely brittle, receiving a fine polish ; 
 giving to the action of the magnet less recipience 
 than iron, nickel, or cobalt ; sustains scarcely any 
 alteration because of being kept under water ; does 
 not solicit oxygen during exposure to the atmo- 
 sphere ; yet it does so, and gradually becomes oxi- 
 dised, at a high temperature. It is sluggish to the 
 solicitings of acids, even at a boiling temperature ; 
 and by nitro-muriatic acid is solicited, and forms 
 muriate of chromium. It will sustain an extremely 
 high temperature, not yet precisely determined, but 
 above 170 of Wedgwood's pyrometer ; and in that 
 of the biscuit-oven for hard porcelain it is reduced 
 
310 CHEMISTRY OF POTTERY. 
 
 into small grains. Its combinations with oxygen 
 form the green, brown and yellow oxides. 
 
 To obtain the chromium ; Process. The mineral chromate of 
 iron in very fine powder, two parts, and one part of nitrate of 
 potash well mixed, fuse together during two hours at a high 
 temperature, in skittle-shaped crucibles for the large processes ; 
 otherwise, for experiment, in a silver crucible when convenient. 
 When cold, break the crucibles, and the whole of the spongy 
 mass with the shreds cover with ten times their weight of pure 
 water ; boil one hour ; the liquid, when cool, decant off, and the 
 residuum similarly treat, until no more colouring matter is supplied. 
 The water then very slowly evaporates to one half ; add test 25, 
 filter out the silicate and the aluminate of potash ; again add test 
 1 till the liquid is alkaline and has a yellowish tint. The evapo- 
 ration is repeated slowly, cool, leave the liquid to repose that 
 the nitrate of potash may crystallise, with scarcely any of the 
 chromate of potash of the liquid. This evaporate to a pellicle, 
 and abstract the beautiful crystals of bi-chromate of potash ; 
 which process repeat for a second supply ; and the remaining 
 supernatant liquid again evaporate to supply the neutral yellow 
 sub-chromate of potash. 
 
 2. The calc pulverise, and in plenty of pure water digest 1 hour ; 
 after 24 hours' repose carefully decant the liquid by employing 
 the siphon ; to the precipitate add test 26, agitate, and after two 
 minutes by the siphon abstract the aciduline liquid. To the resi- 
 duum add, as before, one-fourth of nitrate of potash ; again calcine 
 for two hours, and repeat the treatment till all the mineral is 
 suspended in the liquids. These last evaporate one half ; slightly 
 acidulate with test 25, and continue the evaporation till a pellicle 
 forms on the surface, when place the liquid aside to crystallise, 
 and separate from any impurity present. The salt thus obtained 
 pulverise and mix with water, then again slightly acidulate with 
 test 25 ; evaporate as before, and obtain all the crystals of nitre by 
 a repetition of the process ; the menstruum again evaporate, let it 
 repose 14 days, remove the yellow crystals, dissolve in pure water, 
 again evaporate, and crystallise for chromate of potash (P 1 
 + Cl + O2;orlO + 7+8 = 25). Or, to the solution of 
 the salts add test 20 ; the orange-red precipitate of chromate of 
 mercury (M 1 + C 1 + O 2, or 25 + 7 + 8 = 40) filter out, 
 
METALS. 311 
 
 wash well, evaporate dry, and in a porcelain retort raise to incan- 
 descence, and there will remain the protoxide in a state of purity. 
 Eichter obtained the metal by mixing the protoxide with sugar, 
 and exposing the mass to the temperature of a porcelain oven. 
 
 From chromium we obtain the protoxide brown, 
 the deutoxide green and the acid, orange-yellow, 
 whose components respectively are C 1 + 1 ox., 7 
 + 4 = 11; C 4 + 3 ox., 28 + 12 = 40 ; C 2 + 3 ox., 
 14 + 12 = 26. 
 
 Processes. 1. Green Oxide. In muriatic acid digest the ore, 
 and when the acid is fully saturated, or the mineral completely in 
 suspension, evaporate dry, and by raised temperature dissipate 
 excess of acid ; mix well in pure water, add test 2, filter out, and 
 wash well the precipitate ; again evaporate the liquid, and add 
 test 2 ; filter as before, and when evaporated dry incandesce the 
 salt. 
 
 2, 3, 4. Ignite in a close vessel chromic acid, oxygen will 
 evolve, and leave the green oxide. Or, ignite together chromate 
 of potash, carbonate of potash, and sal-ammoniac ; or, chromate 
 of lead and some oil or charcoal; the green oxide results. 
 
 5. In water dissolve chromate of potash, then add tests 32 
 and 21 or 26, and boil well ; allow 24 hours' repose, and filter 
 out the greenish-blue hydrate, soluble in most acids, until it has 
 been incandesced, when it becomes insoluble. 
 
 6. In tests 26 and 32, equal quantities, for 1 hour digest 
 crystals of chromate of lead, and let it repose 24 hours ; filter out, 
 and wash well the muriate of lead with alcohol and with pure 
 water ; the liquid evaporate almost dry, and then incandesce in a 
 platinum crucible. The oxide when precipitated from aciduline 
 solutions is always of a deeper tint, readily soluble in acids, and 
 has water present that is easily evaporated. 
 
 7. To the solution of chromate of potash add test 36 till pre- 
 cipitation ceases ; filter out the chromate of barytes and wash 
 well ; add test 24, and digest 30 minutes, then filter out sulphate 
 of barytes ; with care evaporate, and allow to crystallise into ruby- 
 red crystals, with some difficulty obtained, and with avidity so- 
 liciting moisture from the atmosphere ; again mix in pure water , 
 
312 CHEMISTRY OF POTTERY. 
 
 and recrystallise twice for the pure chromic acid, which has a 
 very sour and metallic savour, and deep red colour. The sul- 
 phate of barytes must also be examined, as with it may precipi- 
 tate some oxide of chromium, and also oxide of iron or copper, 
 if present. The acid has strong combinative potency with several 
 of the bases, alkaline, earthy, and metallic, and with oxygen is 
 separable only by very high temperature, yet readily by protoxide 
 of iron, leaving protoxide of chromium. Sulphuretted hydrogen, 
 sulphurous acid, and protoxides of iron, copper, and tin, convert 
 the acid into the green oxide. 
 
 8. Chromic Acid from Chrome Ore. Put equal weights of 
 chrome ore and nitrate of potash into a crucible in an air furnace, 
 and fuse at least 2 hours ; when cold, wash all the calc out, filter, 
 and the liquid will be a solution of Chromate of Potash. Acidu- 
 late with test 25, then add test 30, and when chromate of barytes 
 ceases to precipitate filter it out, and in a capsule immediately 
 add test 25 to dissolve it ; then add test 24 very dilute, till the 
 precipitate ceases, filter it out, and the liquid will be water, nitric 
 and chromic acids ; evaporate this dry, and by raised temperature 
 dissipate the nitric acid, and the red chromic acid secure in well- 
 stoppered phials. The solution is yellow, and with a concen- 
 trated acid forms the {chromic oxide, whose solution is green. 
 
 9. In nitric acid dissolve the green oxide, evaporate dry, and 
 then by raised temperature dissipate all nitrous vapours ; filter out 
 the brilliant brown powder, insoluble in acids, and only slug- 
 gishly soluble in alkalies. When test 26 is added, and the tem- 
 perature raised, chlorine gas evolves, and the protoxide is formed, 
 proving that previously more oxygen was present than now is in 
 the protoxide. 
 
 The green oxide, at a temperature just below 
 incandescence, is extremely combustible, and al- 
 though sluggish to nitro-muriatic acid, is readily 
 oxidated in a furnace, by fixation of oxygen, especi- 
 ally in presence of an alkali. When it becomes 
 ignited the bulk diminishes by loss of its water, and 
 the colour becomes a very deep green, almost black ; 
 at a yet higher temperature it inflames, and blazes 
 
METALS. 313 
 
 intensely 1 or 2 minutes, without either gaining or 
 losing any portion of its weight ; next it acquires the 
 precise temperature of the combustibles around, and 
 then its colour is a beautiful and fine light green 
 with *5 of water. Before incandescence the salt was 
 readily soluble in acids, which is neutralised, but 
 after this it becomes altogether insoluble, indifferent 
 to the solicitings of acids, or alkaline leys, indi- 
 cating that the reaction has caused a more intimate 
 combination between oxygen and chromium, or at 
 least, an increased aggregation in the particles of the 
 oxide. Berzelius regards this phenomenon as very 
 peculiar, because it occurs when a portion of the 
 oxygen is disengaged, and the mass is reduced to a 
 .sub-oxide. 
 
 The chromic acid contains twice as much 
 oxygen as the green oxide, and one and a half 
 times as much as the base by which it is neutralised. 
 Had twice as much oxygen been present in the 
 green oxide as is requisite to form the acid, this dose 
 of oxygen could not be a multiple by a whole num- 
 ber of that in the neutralising base, and if the green 
 oxide contained thrice the oxygen necessary to con- 
 vert it into acid, the quantity of oxygen in that oxide 
 would seem incredible. Then the green oxide can 
 contain of oxygen only half the quantity needful to 
 form the acid. 
 
314 CHEMISTBY OF POTTERY. 
 
 COBALT. 
 
 THIS mineral has a grey tint, with rather a 
 shade of red, and dull metallic lustre, the specific 
 gravity 8 '7. It is not hard, has very little tenacity, 
 is rather brittle, and readily pulverised, malleable 
 when incandescent, and its texture varies according 
 to the degree of heat employed for its fusion ; it melts 
 at 130 of Wedgwood's pyrometer, but by no heat 
 is it completely volatilised. When incandescent it 
 does not decompose water, neither does it, when 
 cold, oxidise in air or water. 
 
 During several centuries has this mineral been 
 employed to supply a blue tint to glass, but only 
 during one century has any investigation of its 
 chemical properties been instituted. Brandt, in 1733, 
 obtained from the mineral the metal which he 
 named COBALT. In the edition of 1820, vol. L, 
 p. 410, Dr. Thomson says : " Considerable attention 
 has lately been paid to the purification of this metal, 
 but, hitherto, no one seems fortunate enough to hit 
 upon a method altogether free from objections." 
 In Gehlen's Journal, vol. IV., p. 117, Tromsdorff 
 publishes this : 
 
 Process. Mix intimately 8 oz. of pulverised zaffre, 1 oz. 
 pulverised charcoal, and 2 oz. dry nitrate of potash, and into a 
 crucible, in a state of incandescence, of this mixture project very 
 small quantities, and let the whole remain at the same heat one 
 hour ; then allow to cool, pulverise the calc, add the like propor- 
 tions of charcoal and nitrate of potash, and thrice repeat the pro- 
 cess of projection. After the third fusion, cool and pulverise th& 
 
METALS. 315 
 
 calc, and add black flux 10 per cent., and during one hour keep 
 incandescent ; when cool, separate the metallic cobalt, pulverise, 
 blend with thrice its weight of nitrate of potash, and this mixture 
 detonate as already directed. Whatever iron is present will be 
 formed into a peroxide, and the arsenic acid will combine with 
 the potash, and may be separated by copiously working the pul- 
 verised mass in boiling distilled water ; then filter, and well wash 
 whatever remains on the filter. Having by this process separated 
 the arseniate of potash, the contents of the filter digest in nitric 
 acid, test 25, which will now dissolve the cobalt, and not solicit 
 the peroxide of iron. Again filter, wash, evaporate dry, re-dis- 
 solve in test 25 to obtain any spice of iron which possibly may 
 remain ; filter this out, and wash well, the liquid alkalinise with 
 test 1 ; filter out the precipitate, wash well with warm water, and 
 the contents of the filter reduce in a porcelain crucible. 
 
 Dr. Henry says : " The ore dissolve in nitro- 
 muriatic acid ; add test 3, filter out the iron and 
 arsenic ; add more of the test, and the greyish-red 
 oxide of cobalt precipitates. Incandesce the filtered 
 metals, and the latter will volatilise." 
 
 When the mineral in an incandescent state is 
 exposed to the atmosphere, it solicits to combination, 
 in two proportions, oxygen, and the metal gradually 
 becomes an oxide in powder, with 27 '3 per cent., to 
 form the deutoxide, cobalt 2 x oxygen 3, of a tint 
 so dark as to seem almost black; and at a higher 
 temperature this peroxide loses 9*5 to 9*9 per cent, 
 of oxygen, and forms the protoxide cobalt 3 x 
 oxygen 1, with a blue tint of varied strength from 
 adventitious conditions. When this protoxide is 
 subjected to a very high temperature a red flame 
 evolves ; and as any alumine present receives from 
 this a blue tint, I assume that the metal is partially 
 volatilised. The oxide gives the most beautiful blue 
 tint, first to silica, and next to alumine ; which tint is 
 
316 CHEMISTRY OF POTTEEY. 
 
 rendered greyish, proportionately to the magnesia, 
 lime, chalk, or Paris white, present during the 
 baking, and it is almost violet when iron is present. 
 
 In the several steps of the process it is observed 
 that carbon covers the outer film, or surface, to 
 saturation ; the next interior film solicits and appro- 
 priates a considerable portion of this carbon, and 
 after it is almost saturated again is the outer film 
 saturated ; the like result ensues with a third film, 
 and in succession, until the most interior is fully 
 saturated, and the others to the exterior. During the 
 state of incandescence the surface of the metallic 
 bath, saturated with carbon, has this solicited by the 
 oxygen of the air, and burned as carbonic oxide. 
 This is replaced by other carbon, which exudes from 
 the interior, as does water from a porous body, and is 
 similarly solicited by the oxygen, and burned, until 
 no more carbon remains present. By this process 
 the metal is properly oxidised, as well as by the 
 mutual reaction of the metal and the oxygen, in the 
 repeated fusions, adopted for that purpose more than 
 to separate impurities from the metal. Metallic 
 baths being, like the surfaces of metals, in varied 
 degrees affected by the oxygen of the air, whenever 
 of two or more metals in combination (as cobalt and 
 nickel ; cobalt, bismuth, nickel, iron and arsenic), 
 one, because of greater momentum, solicits oxygen 
 with greater combinative potency than the other ; 
 while they remain in contact it will appear more 
 potent, though not in combination, than the latter, 
 which while really passive or receptive solicits only 
 its regular dose of oxygen. 
 
 The mineral, in acids, is soluble without 
 
METALS. 317 
 
 effervescence. When the menstruum is test 26 the 
 solution is green, but by dilution becomes light-red, 
 similar to the solutions with tests 24, 25. Add test 
 1, filter out the precipitate, wash well, and dry in 
 air, for the peroxide ; and then subject it, during one 
 hour, to incandescence for the protoxide. The prot- 
 oxide is soluble in test 2, even though nickel may be 
 present ; and these may be separated by carefully 
 acidulating with test 24, and then crystallising the 
 liquid. 
 
 On drawing from the muffle a crucible of fused 
 cobalt, when the surface appears congealed, place it 
 in an inclined position, and while cooling there will 
 be formed irregular prismatic crystals. The metal is 
 magnetic. 
 
 The mineral is solicited and the metal oxidised 
 by tests 24, 25, and 26 hydrogen evolving when 
 24 or 26 is employed. 
 
 The sulphate of cobalt (whose elements are 
 Cob. 1 + S. 1 + Ox. 2, or 7 + 4 + 8 = 19) can be 
 crystallised by the usual process of evaporation till a 
 pellicle forms on the surface, and then left to cool ; 
 and these crystals on being distilled lose 42 per cent, 
 of water, become opaque and rosy, and thus, without 
 being decomposed, can endure a red heat, except 
 the portion immediately in contact with the retort. 
 When the sulphate is separated in water, add test 8 
 till all precipitation ceases, which will be when about 
 40 per cent, of the sulphate is decomposed. This 
 precipitate is soluble in excess of the test, and also 
 in water at any heat. The retort completely fill, and 
 gradually heat to dissipate the water and carbonic 
 acid, when will remain 60 per cent, of greenish-grey 
 
318 CHEMISTRY OF POTTERY. 
 
 pure protoxide (without this care, a portion will 
 be peroxide, as verified by oxygen evolving when 
 test 26 is added). This grey oxide is soluble in 
 test 25, without evolving nitrous gas ; and by heat 
 in open air is rendered black, a mixture of prot-and 
 per-oxide, the former soluble in acetic or other weak 
 acid, and in test 2. 
 
 With test 1 alkalinise boiling water, and add 
 test 33 till the blue precipitate ceases ; continue the 
 ebullition till the precipitate forms a rosy hydrate. 
 When cold water is employed, instead of a hydrate 
 resulting the blue precipitate becomes green, change- 
 less by contact of air, or drying evaporation. And 
 when recently prepared, boiling in test 1 renders this 
 latter a reddish-grey a mixture of hydrate and 
 black oxide. The first of these three precipitates 
 dissolves in weak acids, which separate the black 
 oxide from the other two ; and oxygen does not 
 evolve on adding test 26 to the blue oxides, as when 
 -added to the green. This most pertinently illus- 
 trates the reciprocal combinative potencies of oxides 
 of the same metals. 
 
 The blue oxide results from the metal being 
 solicited by oxygen from the air present in cold 
 liquids but whence results the green ? This beauti- 
 ful characteristic grass-green oxide cannot result 
 from a mere mixture of the blue and black oxides. 
 Only chemical combination forms a tint different 
 from that of the mixture of its components ; and it 
 only can prevent atmospheric action converting into 
 peroxide the portion of blue oxide present in the 
 green precipitate, which latter only by evaporation 
 and drying is completely oxidised. Only is the 
 
METALS. 319 
 
 blue protoxide soluble in acids. The green oxide is 
 never supplied by any solution, nor is it the base of 
 any salt. 
 
 The grey oxide put into a phial of test 2, stopped 
 close instantly afterwards, imparts a rosy changeless 
 tint, showing the slow momentum of the alkali 
 to combine with the metal. But carbonic acid, on 
 admission of air, or the presence of a carbonate, 
 readily excites the momentum, and the colour quickly 
 results. When the test is merely saturated with 
 carbonic acid the liquid is a compound solution 
 of oxide of cobalt in carbonate of ammonia ; but a 
 continued supply of carbonic acid makes the solution 
 of carbonate of cobalt in carbonate of ammonia, 
 which in a full and closed phial deposits crystals of 
 metallic carbonate (also, on adding water, a portion 
 precipitates) resoluble in excess of test 2. Carbonate 
 of cobalt and carbonate of soda readily form this 
 solution. 
 
 On adding test 2 to super-carbonate of cobalt it 
 solicits the acid of one portion, which latter as a 
 hydrate precipitates, while the other dissolves in the 
 solution of carbonate of ammonia. Also, well- washed 
 and dry hydrate, or blue oxide, in a full phial of 
 test 2, instantly stopped, after 24 hours tinges the 
 liquid red, like the preceding. But there is a great 
 difference ; the precipitate, on pouring this very 
 slowly into boiling water, is the blue oxide ; into 
 cold water, is the green. The extreme comminution 
 of the recent hydrate and blue oxide renders them 
 more soluble than the grey in test 2. 
 
 Hydrate of Cobalt. Crystals of sulphate or 
 nitrate of cobalt add to a phial filled with test 1, and 
 
320 CHEMISTRY OF POTTERY. 
 
 instantly stop close. The salt precipitates blue, then 
 assumes a violet tint, and lastly forms a rosy hydrate ; 
 which, filtered out, washed, and boiled in test 1, sup- 
 plies some oxide, and becomes a most beautiful blue 
 colour. Adding water separates the solution, and 
 admitting the air precipitates the black oxide. The 
 recent rosy hydrate is soluble, and tinges test 1 red ; 
 the oxide is insoluble. Also the hydrate is soluble 
 without effervescence in heated acids, but not by 
 boiling in either pure water or alkaline ley. Heat 
 evaporates 20 per cent, of water, and leaves a grey 
 oxide pure, changeable under water, and rendered 
 black by the atmosphere. Dry hydrate keeps better, 
 yet it solicits carbonic acid from the air. But sub- 
 stituting test 2 for 1, the blue precipitate is change- 
 less, and never becomes rosy. The hydrate formed, 
 instantly solicited by the alkali, tinges the solution. 
 
 The peroxide is insoluble in tests 1 and 2, and 
 soluble in 24 and 25 only after being converted into 
 a protoxide. With test 26 oxygen evolves. With 
 sulphurous and nitrous acids it forms a protosul- 
 phate and protonitrate. Distillation forty minutes in 
 a retort dissipates the oxygen, and leaves the grey 
 oxide ; applicable to tinge vitreous bodies. 
 
 The grey oxide in test 26, heated, forms a deep 
 blue muriate, easily supplying crystals of blue chlo- 
 ride, which atmospheric moisture renders red. The 
 solution of black oxide is green until the oxygen 
 ceases to evolve, when it becomes blue ; which traced 
 and dried on paper exhibits an hydrous chloride 
 unless a spice of nickel supply a yellow tint, and so 
 is formed a green. A chloride results from incan- 
 descence in a luted retort ; the portion of salt in 
 
METALS. 321 
 
 contact with this decompose, and tinge it blue ; the 
 other portion sublimes of a gridelin tint ; so con- 
 densed that the solvency of water often is sluggish 
 more than twelve hours in commencing the formation 
 of the muriate. 
 
 Arsenite of Cobalt. Into a solution of arsenite 
 of potash pour a dilute solution of cobalt salt ; filter 
 out and dry the rosy precipitate ; then decompose it 
 in a closed tube ; the arseniac acid sublimes, and the 
 glass is tinged blue. The resulting salt is soluble in 
 test 25, and nitrous gas evolves. Adding test 15 to 
 its muriatic solution it precipitates orpiment, but 
 test 1, warmed, precipitates the blue oxide. The 
 arseniate of cobalt results when the arseniate of 
 potash is substituted for the arsenite. The precipi- 
 tate also is rosy, and soluble in test 25, but in the 
 tube it becomes violet, without tinging the glass. 
 And adding 15 to the muriatic solution only pro- 
 duces a result after many hours' repose. Test 1 acts 
 as by the other, and solicits the acid. 
 
 Humid Separation of Nickel from Cobalt. 
 
 The celebrated Hermstadt having directed to " dissolve the 
 spiced salt in ammonia, and evaporate the solution, " Bucholz 
 (in 1803) tried these processes : 
 
 (1.) In nitric acid, at 1-220 heated, with equal volume of water, 
 dissolved 1 oz. of cobalt ore (speiss) ; three drams of crystallised 
 arsenious acid precipitated, and was filtered out. On adding to 
 the liquid half a volume of water, it assumed a dull- green tint ; 
 being again filtered, and treated with six volumes more of pure 
 water, precipitated a spice of oxide of bismuth, which was re-dis- 
 solved by adding test 2. The next filtration supplied a mixture of 
 arseniate of cobalt, and oxides of bismuth and iron. The filtered 
 
 Y 
 
322 CHEMISTKY OF POTTERY. 
 
 liquid had a beautiful blue tint, and by gentle evaporation supplied 
 about two drams of a bright green residuum of oxides of nickel 
 and cobalt ; arid rapid evaporation supplied a like result. The 
 deep green saline result of ammoniacal nitrate of nickel thus sup- 
 plied, was re-dissolved in water, filtered, and boiled in test 1 till 
 all the ammonia was dissipated, when 1| drams of oxide of nickel 
 was obtained, apparently free from oxide of cobalt. 
 
 (2.) The preceding process being operose and indefinite, he 
 tried sulphuric acid. To the like weight of cobalt ore the same 
 quantity of water was supplied, the temperature raised, and 
 sulphuric acid added till all was dissolved, chlorine gas evolving 
 (to his great surprise). The resulting precipitate was dissolved 
 'by test 2, except a residuum, much like verdigris, mostly oxide of 
 cobalt, slightly spiced with oxide of nickel. The liquid being 
 condensed by evaporation, and filtered, supplied more cobalt 
 similarly spiced. It was next rapidly evaporated properly for 
 crystallisation, and left to repose forty-eight hours, when were 
 formed groups of green prisms, and masses of blue-edged crusts, 
 both having almost equal proportions of cobalt present ; as verified 
 by the assay of the oxides procured by potash from the solution 
 of the crystals, and from the menstruum. 
 
 (3.) On subjecting 8 oz. of cobalt ore to the process already 
 mentioned, the first, bluish-green crystals, about 5 oz. were dis- 
 solved in 3 J oz. of boiling water, then properly evaporated, filtered, 
 and left nigh a stove to cool slowly and crystallise. After forty- 
 eight hours were formed beautiful yellow-green short rhomboidal 
 pyramids, whose faces and angles proved cooling preferable to 
 slow evaporation for forming regular crystals. All were carefully 
 collected, well washed with pure water, then re-dissolved, and 
 boiled with test 1 till all the ammonia evolved, and all the nickel 
 was separated. 
 
 (4. Most efficient.) Equally to dissipate the carbonic acid, and 
 to determine the absence of cobalt, this oxide was dissolved in 
 test 25, and the solution alkalinised with test 2. The fine blue 
 liquid by filtration supplied 5 grains of what seemed oxide of 
 cobalt. The whole was evaporated dry ; the residuum was re-dis- 
 solved in test 25, and on adding test 2, four drams precipitated of 
 a beautiful bright green oxide. The filtered liquid, treated with 
 test 1 at 212 Fahrenheit, supplied 170 grs. of pale-green oxide of 
 nickel with carbonic acid. Some of this dissolved in test 26, and 
 
METALS. 323 
 
 applied to paper, by heat assumed a slightly greenish-yellow tint ; 
 but the oxide of nickel spontaneously separated during evaporation, 
 being similarly treated, much chlorine gas evolved ; and applied 
 to paper, by heat assumed the tint of highly-saturated sympathetic 
 ink of cobalt, proving more cobalt present in the solution than in 
 that of the precipitate. The two oxides thus supplied, incandes- 
 cence rendered dark grey ; and in nitric and sulphuric acids, 
 nitrous gas evolved from the evaporated residuum, and also the 
 alkaline ley ; and ammonia caused like results to those previously 
 mentioned. 
 
 Therefore, the sulphates and nitrates of ammoniacal nickel 
 separated from cobalt ore retain some cobalt, not separable by 
 Hermstadt's process. And, partially decomposing, by evapora- 
 tion, the ammoniacal nitrate of cobalt supplies an oxide of nickel, 
 very rich in cobalt, but with nitric acid present ; and the unde- 
 composed oxide of nickel has very little cobalt present. 
 
 (5. Laguier's.) By well roasting the ore dissipate the arsenious 
 acid ; dissolve in test 25, filter, wash, and dry oxide of arsenic. 
 Pass test 14 through the liquid, filter out, and wash the copper ; 
 boil to dissipate test 14 ; add carbonate of soda ; filter out the 
 precipitate, and digest in test 7 for the iron ; add test 2, filter out 
 the precipitate, and expose the liquid to the air ; the tint, from a 
 violet blue, becomes red ; acidulate with test 7, filter out the deep 
 green oxalate of nickel, wash well in boiling pure water ; the red 
 ammoniacal liquid evaporate dry for the pure cobalt. 
 
 Y 2 
 
324 CHEMISTRY OF POTTERY. 
 
 COPPER. 
 
 THIS well-known metal, common in veins and 
 beds in the mines of Cornwall, Anglesea, Spain,. 
 Germany, Norway, Siberia and America, is hard, 
 sonorous, malleable, ductile, with considerable tena- 
 city, and a peculiar reddish-brown colour, liable to 
 tarnish and oxidise from exposure to the atmosphere. 
 Its name originated from that of the isle of Cyprus, 
 where it was first obtained and worked by the Greek, 
 although long previously it had been known, pro- 
 bably as early as silver and gold ; and before iron was. 
 so employed it was formed into vessels and weapons. 
 It is harder than silver ; its specific gravity is 8*830, 
 or 8 '895 ; its malleability admits of being hammered 
 out into leaves so thin as to be blown about by the 
 slightest breeze ; it has considerable ductility ; and 
 its tenacity is sufficient for a wire 0*078 of an inch 
 diameter to support 302*26 Ibs. without breaking. 
 Two bars of copper, one cast, the other hammered, a 
 quarter of an inch in diameter, respectively supported, 
 before they were broken, 1192 and 2112, almost 
 double for the latter ; and much greater is the dif- 
 ference in two wires of one-tenth of an inch diameter ; 
 the cast supports only 1907, and the wrought 337*9 
 Ibs. avoirdupois. 
 
 Pure water does not oxidise copper, but by it 
 in a state of incandescence is decomposed, while its 
 surface is oxidated ; and the line of contact of water 
 in a copper vessel is distinguished by a green ace- 
 tate, or verdigris. At the common temperature of 
 
METALS. 325 
 
 the atmosphere, 60 Fahrenheit, in air the surface of 
 a plate of polished copper forms very sluggishly and 
 gradually a brown and a dark greenish-brown very 
 thin crust of oxide, with carbonic acid gas ; yet 
 thin as is this covering, it preserves from further 
 corrosion the metal beneath. 
 
 While approaching, but at a temperature much 
 below incandescence, the surface of a plate of polished 
 copper irridesces, or gradually becomes covered with- 
 beautifully-variegated marblings of prismatic colours, 
 the red of each series being nighest the extremity 
 most heated ; and the orange, yellow, and blue tints 
 forming the elegant foils employed to ornament 
 children's toys. That these are results of oxidation, 
 I assume, because the stratum of coloured matter is 
 always thickest where has been applied the highest 
 temperature, and it gradually diminishes or grows 
 thinner towards the coldest extremity. 
 
 At a higher temperature, or incandescence, a 
 plate of polished copper oxidises rapidly, its surface 
 in a few minutes being covered with a crust of oxide, 
 forming thin powdery scales, which when the plate 
 is cool spontaneously separate, or may readily be 
 rubbed of, because the plate itself had its dimensions 
 expanded during the incandescence, and was so 
 expanded while soliciting the oxygen, and while 
 the oxide was formed ; but having contracted to its 
 primary dimensions, the oxide separates in scaly 
 fragments. 
 
 This suggests a ready mode of obtaining a supply 
 of peroxide of copper for the common underglaze 
 Black. Alternately incandesce the plate of copper, 
 and immerse suddenly in cold water ; the scales 
 
326 CHEMISTRY OF POTTERY. 
 
 separate and precipitate in the water to the bottom 
 of the vessel. The small portion of metallic copper 
 which remains on their under surface causes them to 
 seem violet-red ; but when incandesced in air, they 
 become the black and pure peroxide of copper. 
 This black powder is devoid of savour, or lustre, 
 or effervescence while dissolving in acids, and the 
 menstruum is blue, or green, as it is test '24 or 26. 
 There are different tints of brown, green, or blue 
 with the peroxide, whose components are C. 1 + Ox. 
 2, and the protoxide, C. 1 + Ox. 1 ; native has a red 
 tint, and artificial a fine orange. The flame of the 
 fuel, during the incandescence, assumes a beautiful 
 bluish-green colour. 
 
 At the temperature of 1150 Fahrenheit, or 27 
 Wedgwood (below that needed for gold and silver), 
 copper melts, and its surface exhibits a bluish-green 
 flame, like that of melted gold ; and after fusion, 
 when allowed to cool very slowly, a mass of crystals, 
 of quadrangular prisms, are formed. At 40 Wedg- 
 wood it volatilises in visible fumes, partially metallic. 
 When subjected to the oxy-hydrogen blow-pipe 
 flame, the metal burns with an intense lively green 
 light, whose brilliance is very oppressive to the eye. 
 
 A polished iron plate, immersed 24 hours in a 
 liquid, aciduline by test 25, or 26, will solicit what- 
 ever copper may be present, and retain it as a 
 metallic coating. 
 
 The tests 24 and 26 less, and the test 25 most 
 potently, solicit copper ; the oxygen combining with 
 the metal while nitrous gas evolves, and the surplus 
 acid is appropriated by the oxides. The deutoxide 
 may be formed by dissolving the metal in 24 or 25 ; 
 
METALS. 327 
 
 then add test 1, filter out, wash, and completely 
 evaporate the precipitate. The perchloride may be 
 formed by gently heating test 26 in which is copper 
 chips ; decant the green solution, add rolled copper, 
 and closely stop the phial ; the green colour soon is 
 superseded by a dark brown, opaque ; many dusky 
 white crystals form, which may be abstracted and 
 again dissolved in water ; to this, or to the whole 
 solution, add test 1 ; filter out, wash, and evaporate 
 dry the precipitate. The protochloride has a yellow 
 tint, and the deutochloride is a yellowish-brown 
 powder ; when formed by igniting copper filings in 
 chlorine gas, the former remains fixed, the latter 
 sublimes. The muriatic solution supplies soluble, 
 deliquescent, prismatic crystals. The colour of the 
 precipitate, as green or blue, results from the potash, 
 or soda, being less or more ; and this has much acid, 
 while it spices the other. 
 
328 CHEMISTRY OF POTTERY. 
 
 GOLD. 
 
 GOLD is devoid of perceptible savour or odour ; 
 its specific gravity 19*3 ; its lustre not affected by 
 exposure to air or water ; yet inferior to that of 
 platinum, silver, mercury and polished steel ; it is 
 remarkably flexible, but in hardness superior to lead 
 and tin, and inferior to iron, copper, platinum and 
 silver ; in ductility and malleability surpassing all 
 other metals. A wire of 0'078 of an inch in dia- 
 meter will, without breaking, support 150*07 Ibs. 
 avoirdupois ; yet this tenacity is not equal to that of 
 iron, copper, platinum, or silver ; one grain of gold 
 can be beaten out into leaves 2l ^ f an mcn m 
 thickness ; yet this is 12 times the thickness of the 
 gold which covers the silver wire of gold lace, for 
 1 oz. of gold on silver wire can be extended by the 
 drawing-mill above 2,288,000 yards, or 1300 miles. 
 In the focus of a burning mirr6r, or the oxy- 
 hydrogen blow-pipe flame it fuses and vapourises. 
 At 32 Wedgwood it fuses, is of a bright blue-green 
 colour, and expands much ; but on resuming its 
 solid state it contracts more than any other metal, 
 and therefore is ill adapted for casting into moulds ; 
 slow cooling crystallises it into short quadrangular 
 pyramids. 
 
 Gold is among the metals first known, and it is 
 supposed by many to have been the first employed 
 for any useful purpose ; and because of its scarcity 
 and remarkable properties, as with the early societies 
 it was estimated as most valuable, the like preference 
 
METALS. 329 
 
 continues to the present day. Almost the whole 
 supplied to the market is found in a metallic state. 
 It is the only metal of a reddish-yellow (almost 
 orange) colour found in nature in a metallic state, 
 most commonly in the sands of some rivers in 
 Africa, France, Hungary and Brazil, in Wicklow, 
 Ireland, and at Leadhills, Scotland, in minute irre- 
 gular grains (called gold du$i), also in ramifications, 
 leaves, or crystals, in a matrix of a silicate, quartz, 
 sand-stone, silicious schist, etc. When found native 
 in compact masses, it is ever alloyed with silver or 
 copper, or even iron and tellurium. The largest 
 .known specimen, scarcely alloyed, about 22 oz., 
 hitherto discovered in Europe, and many smaller 
 pieces, 1 oz. and upwards, were found beneath a 
 stratum of turf on sand, near a small rivulet in the 
 County of Wicklow, Ireland. It has been obtained 
 by some of the French chemists from the ashes of 
 vegetables. Hungary supplies gelf, argentiferous 
 pyrites, with the gold ore either massive, or 
 rhomboidal crystals, or irregular quadrangular or 
 polygonal masses. The sulphuretted ores of 
 Nagaya, in Transylvania, likewise supply gold. 
 
 A very high temperature is needed to oxidate 
 gold in common air, because without this it will 
 sustain incandescence an almost indefinite period. 
 It can be brought into a state of purple oxide by the 
 discharge of the electrical battery, or in the forma- 
 tion of the galvanic circuit, the focus of the large 
 lens, and gas blow-pipe. The chlorides of gold and 
 silver differ completely ; the latter is extremely 
 .alkaline, partially soluble in water, and solicits all 
 
330 CHEMISTRY OF POTTERY. 
 
 acids presented ; the former has none of these pro- 
 perties, yet at very high temperatures it is decom- 
 posable ; while the latter, free from the contact of 
 water and hydrogen, remains unchangeable by the 
 highest temperature. 
 
 The only solvent of gold (also of platinum) is 
 the liquid named aqua-reyia (the kmcf* witer), but 
 respecting the proportions of the component acids 
 analytical chemists entertain different opinions. 
 Proust directs, muriatic acid at 12 Beaume, 800 
 parts, and colourless nitric acid at 40, 200 parts, 
 and a raised temperature (the latter to oxidate the 
 former) to dissolve 187 grains of gold. Ure directs 
 the proportions to be, 33 and 67, and Davy 66 and 
 34, stating that there ensues reciprocal separation 
 and combination, preparing the metal for combina- 
 tion with chlorine as long as it is evolved, but 
 ceasing therewith. On the mixture of the two acids 
 effervescence occurs, because the nitric acid solicits 
 some of the muriatic acid, whose hydrogen appro- 
 priates sufficient oxygen from the other to compose 
 water; and the nitrous gas is liberated while the 
 chlorine remains to solicit the metal exhibited in 
 small supplies till all is dissolved. The nitro- 
 muriatic acid is usually orange-coloured, which 
 changes to a deep yellow when saturated. When 
 this is exposed to the solar rays the metal forms 
 a hydrate, or an hydrous chloride, with just the 
 equivalents of oxygen and hydrogen appropriable 
 without excess to form water. And sulphuric acid 
 exhibited will appropriate the muriate (or dissolve 
 the chloride) and leave the nitric acid alone. 
 
METALS. 331 
 
 Processes (1.) To crystallise Gold. Add to the solvent 
 excess of gold, next gradually add muriatic acid until its potency 
 is inert, and consequently also that of the nitric acid ; filter, and 
 evaporate till a pellicle commences, then let it repose, and there 
 will form laminated orange-coloured crystals ; to be viewed only 
 in the evaporator, because they are very deliquescent, and also 
 separable by a moderate rise of temperature which dissipates the 
 chlorine, and the metal is left with much water of crystallisation. 
 When the solution is concentrated, the mass coagulates and the 
 crystallisation is proportionately affected. I do not meet with 
 any instance in which the employment of phosphorus has been 
 tried in purposes of the manufacture. When the nitro-muriatic 
 solution of gold is carefully treated with phosphoric acid, all the 
 colour will disappear ; pellicles of metallic gold will swim on the 
 surface, and every atom of metallic gold will be precipitated. 
 
 (2.) To purify Gold by Antimony. Take a good crucible 
 that will contain at least four times the quantity put into it ; bring 
 the metal into fusion, and add twice the weight of sulphuret of 
 antimony ; cover up very close, and keep the fusion until the 
 surface sparkles ; then pour the fused mass into a strong iron cone 
 hot and well greased ; when cold there will be two compounds ; 
 the lower, gold and antimony, in the proportions of the metals 
 sulphuretted ; the upper, sulphurets of antimony and other metals 
 which had been in the alloy. Repeat the process with the anti- 
 mony, till only this and the gold remain. In a large crucible 
 sublime the antimony, and with the bellows blow on the surface, 
 and add a little nitrate of potash to complete the separation. 
 Afterwards fuse the gold with this last, and borax, to get its 
 ductile property restored. 
 
 Gold forms two salitiable oxides, the protoxide 
 and peroxide ; also a deutoxide not salifiable, but 
 present in the purple of Cassius (which article see, 
 Part II.. Chapter 4). The peroxide is best known, 
 because most readily obtained. The solution is 
 slowly evaporated dry, and the residuum is dissolved 
 in pure water; alkalinise with test 1, raise the tem- 
 perature to 150 Fahrenheit, filter out, wash, carefully 
 
332 CHEMISTRY OF POTTERY. 
 
 evaporate, and dry the red-brown peroxide, G 1 + 3 
 Ox. ; a powder, with a styptic and metallic savour 
 causing a flow of saliva, soluble partially in water or 
 nitric acid, and readily in muriatic acid ; its oxygen 
 dissipated by a moderate heat, and reduced metal 
 remaining. When all the chlorine of the permuriate 
 is dissipated, add test 1, and immediately filter out 
 the green protoxide, because delay will present 
 opportunity for one-third of the precipitate to 
 appropriate the oxygen of the other two-thirds, by 
 this reduced to the metallic state, while it forms the 
 peroxide. 
 
 When test 2 is employed the precipitate is 
 alarmingly and dangerously fulminative. On its 
 early discovery, the alchemist Raymond Lully was 
 very nigh falling a victim to its activity ;* and the 
 greatest attention to washing the precipitate is 
 needful, and to dry it on the filter laid on blotting 
 paper. This fulminating potency is neutralised 
 when the salt is immersed in concentrated sulphuric 
 acid, this promoting the combination of the oxygen 
 and hydrogen present into water which is by it 
 appropriated. That the ammoniuret of gold is 
 potent, more because of capacity than momentum, 
 may be concluded from these facts : the oxide is 
 solicited from the menstruum by the carbon 
 organised and hydrogenated in the oils with ether 
 
 * Orschal, in recent times, experienced like danger. He was 
 rubbing in an agate mortar this dangerous salt, when the explosion 
 shattered the stone beneath his hand ; the sensation resembled the 
 discharge of a musket load of sand full in his face, but did not 
 cause a wound, or any other ill effect. 
 
METALS. 333 
 
 and alcohol, and nitrogen hydrogenated in am- 
 monia ; and the oils may appropriate the oxide, 
 and also the ammonia, separate and distinct from 
 each other. Ammonia is too indifferent to water 
 for. this to solicit it from gold, even aided by raised 
 temperature, although this condition excites the 
 potency of the compound, as, when washed with very 
 hot water, the fixation of the oxygen separates the 
 ammonia from the oxide, the hydrogen from the 
 nitrogen, and the gold is left alone, while water 
 results from combination of the elements evolved. 
 The total impossibility of the salt being decomposed 
 by acids will be clear from considering that they 
 either must separate the ammonia, or at once 
 dissolve both components : the former could be 
 only by insulating, at a low temperature, the metal 
 from its oxygen ; the latter, only by the acids 
 soliciting such oxide to combination ; which, if 
 possible, would increase, ad inflnitum, substances 
 with oxygen present. 
 
 When test 17 is used a beautiful purple 
 precipitate results, which, applied to porcelain, is 
 very deep, but only from one point of view. This 
 precipitate partially dissolves by boiling in muriatic 
 acid at 12 ; and the potency of this acid on gold, as 
 on other metals, is proved by test 18 supplying the 
 purple precipitate of Cassius. 
 
334 CHEMISTRY OF POTTERY. 
 
 IRON. 
 
 IRON is distributed through the mineral, 
 vegetable, and animal kingdoms in greater 
 quantity than any other metal, combined with 
 oxygen, sulphur, carbon, arsenic, and other min- 
 eralisers ; and in almost a pure state large masses 
 have been discovered, as in Paraguay, one of 300 Ibs., 
 and one of 1600 Ibs. by Pallas, on the Denisei, in 
 Siberia. Iron, when almost pure, has a slightly 
 vivid whitish-grey or bluish tint, and considerable 
 brilliance when polished. It is peculiar in giving 
 sparks by collision with flint, and in being affected 
 by magnetic potency, appropriating sufficient, 
 under certain conditions, to affect other iron. The 
 specific gravity is 7 '6, the texture fibrous, granular, 
 and laminated ; the hardness, tenacity, ductility, and 
 elasticity superior to all other metals ; it can be 
 drawn into wire finer than a human hair, and 
 readily flattened by pressure ; protected from contact 
 with the fuel, it is refractory in the furnace ; yet, 
 preserving its ductility, it softens, dilates, and in this 
 state possesses the important and valuable property 
 of welding. At high temperatures it solicits oxygen 
 from the air, and when intense, it scintillates, and 
 forms a black oxide, I. 3 + 2 O. It likewise 
 appropriates oxygen, from water, with rapidity 
 proportionate to the temperature of the metal when 
 exhibited ; from the metallic oxides, from nitric, 
 and diluted sulphuric acids ; and is affected by 
 alkaline compounds. Recently has been ascertained 
 
METALS. 335 
 
 a remarkable property of iron, never suspected till 
 demonstrated by bringing to the shore the stores 
 of the Royal Geonje, which foundered in 1782 : 
 the guns formed of hard metal were unaffected, 
 and those of iron are softened by immersion in water, 
 so that a knife cuts them like pencil lead or 
 plumbago. This will account for the frequent 
 failures of the pump-trees in deep mines. 
 
 As only the oxides are employed in this 
 manufacture, I shall state the readiest method to 
 obtain them. 
 
 Processes. 1. Protoxide. In water for several hours digest 
 excess of iron filings ; filter, and the liquid evaporate dry, covered 
 from the air. 2. To a solution of protosulphate of iron add test 2 ; 
 filter out, and in like manner dry the precipitate. This hydrate 
 will change from black to white when dissolved in pure water. 
 
 3. Deutoxide. In a porcelain tube place a coil of fine iron 
 wire, incandesce, and pass through it a current of steam till 
 the supply of hydrogen fails. This will not solicit oxygen from 
 water, and therefore may probably become very useful. 
 
 4. Peroxide. In nitric* acid digest, some hours, clean iron 
 filings ; add test 2 ; filter out, wash well, evaporate dry, and 
 slightly incandesce the brown-red oxide. 5. In an open cru- 
 cible calcine for two hours clean protosulphate of iron (green cop- 
 peras) ; wash well, and evaporate dry the Colcothar. 6. In like 
 manner treat clean iron filings, for the red powder, saffron of 
 Mars. Common iron rust is this, only with plus of carbonic 
 acid. 7. In a current of air similarly treat the protoxide for a 
 yellow. 8. Dissolve clean iron filings in sulphuric acid, dilute 
 much, and expose constantly to the air ; whenever the menstruum 
 is saturated, precipitate by test 2, filter out, and evaporate dry. 
 When pure, this is a beautiful, fine, almost crimson-red. If 
 any yellow or brown tint be present, some impurity has crept in 
 unobserved, and the process should be repeated. The result is 
 insoluble in water, and sluggishly soluble in acids, more so than 
 the protoxide, the liquid being sweetish astringent, with a yellow 
 or brown tint. 
 
336 CHEMISTKY OF POTTERY. 
 
 LEAD. 
 
 LEAD is among the metals known from the 
 earliest days of civilised society. When newly 
 melted the colour is bluish- white, with some 
 brilliance, which soon tarnishes in the air ; and by 
 soliciting the oxygen of the atmosphere, slowly the 
 surface becomes a dirty grey, almost white oxide, 
 which retards further soliciting and oxidation. 
 Lead solicits oxygen from water chiefly when most 
 affected by atmospheric action ; hence the formation 
 of a line of oxide at the part of a water cistern where 
 the water remains a few days at the same level, and 
 also the line of highest level. Lead has very little 
 savour, but friction causes a peculiar odour to evolve ; 
 it stains the lingers bluish, and taken internally is 
 poison. It is a very soft metal ; its specific gravity 
 11*352, increased by hammering in a mould, but 
 decreased by drawing, as wire, and lamination. Its 
 malleability admits of being hammered into very 
 thin lamina ; its ductility is small ; its tenacity 
 causing a wire T!O inch diameter to support 184 Ibs. 
 without breaking. Lead fuses and renders refractory 
 metals fusible at 612, and after fusion, when slowly 
 cooled, it crystallises in quadrangular pyramids, 
 lying on one side, and each formed of three layers ; 
 and at a very high temperature boils, and partially 
 vapourises ; and this continued, it vitrifies alone, or 
 with other metals. 
 
 Lead solicits oxygen to combination, and forms 
 the protoxide yellow, the peroxide brown, and the 
 
METALS. 337 
 
 red oxide, the others mixed. All of these being 
 very easily vitrified, and in high temperatures first 
 oxidate and then combine with other metals, except 
 gold, silver, platinum, and those from this last; 
 lead is employed to separate from gold and silver 
 any base metal present, by the process named 
 cupellation (from cupel, the vessel or test used a 
 shallow cup-like vessel, formed by pressing within 
 an iron ring a mixture of bone earth or ashes,, 
 and wood or fern ashes, and scooping out the 
 surface). Into this cup the alloyed metal is put,, 
 and kept at a high temperature till all the others 
 with the lead vitrify together, and sink into the 
 cupel, leaving the gold or silver. 
 
 The protoxide yellow r (L. '2 + 1 Ox.) has been 
 known longer than the others. Lead dissolved in 
 nitric acid, and its colourless solution alkalinised 
 with test 3, supplies a precipitate, which dried, 
 and heated almost red, becomes yellow, tasteless,, 
 insoluble in water, but soluble in potash and in 
 acids, readily fusible into a semi-translucent, brittle, 
 yellow, permanent glass ; also partially vapourising 
 in high temperatures, and thus exposed to the air 
 some time, the surface is rendered brick-red. 
 
 This last process, at a temperature rather lower, 
 caused a grey pellicle to form as frequently as a 
 prior one is removed,- till the lead is all exhausted. 
 These again exposed while heated and agitated 
 form a greenish -yellow powder (supposed a mix- 
 ture of yellow oxide and metallic lead), which 
 being longer thus treated, the metal solicits more 
 oxygen, and the whole becomes yellow the article 
 of commerce named massicot. 
 
 z 
 
338 CHEMISTRY OF POTTERY. 
 
 Ceruse, White Lead, subcarbonate. Thin plates of 
 cast lead are curled up, and in skit tie- shaped pots 
 are exposed to the vapour of warm vinegar in a 
 vessel beneath ; rows of many hundreds in tiers are 
 gently heated by bark and flues to volatilise the 
 acetic acid, which gradually corrodes the lead into a 
 white heavy powder, a compound of the yellow oxide 
 and carbonic acid, though formerly supposed a 
 peculiar oxide, and when ground in mills much like 
 those for flint, and then dried, is fit for use either as 
 -a component of earthenware glaze, or as a paint. 
 
 Nitric acid, at 40 Beaume, poured on red lead 
 dissolves 185 parts, and leaves 15 parts as a deep 
 brown or black powder. This is the peroxide, L. 4 
 + 3 Ox., or Scheele's Brown oxide. 
 
 Process. Put red oxide of lead into a vessel of water, supply 
 chlorine gas till the oxide is dissolved ; add test 1, and 68 per 
 cent, of the oxide will precipitate as a fine, light, tasteless, flea- 
 brown powder, indifferent to tests 24 and 25, but solicits hydrogen 
 from test 26 ; and by heat half the oxygen evolves, and the 
 yellow oxide again is formed (L. 2 + 1 Ox.). 
 
 Massicot, in a fine powder, constantly agitated 
 while the flame of the furnace plays on its surface 
 48 hours, forms the very heavy, beautiful, often 
 intense, red powder, named minium, or red lead 
 oxide (L. 4 + 3 Ox.), with specific gravity 8*940, 
 tasteless ; and unaltered in weight by 400 Fahren- 
 heit, but by incandescence loses 4 to 7 per cent, as 
 oxygen evolves, and part of the oxide is reduced to 
 metal, the remainder being gradually vitrified dark 
 brown. Only after decomposition does red lead 
 combine with other substances, and because in its 
 
METALS. 339 
 
 plus of oxygen it sluggishly combines with acids, 
 which first form the yellow oxide. 
 
 GALENA, Sulphuret of Lead (having only the 
 minimum of sulphur present), is that very abundant 
 ore which supplies most of the lead of commerce, 
 scattered in almost every country on the globe's 
 surface ; usually in cubical crystals, of a brilliant, 
 deep blue-grey colour, brittle, and more refractory 
 than lead in the furnace. Of native lead, pure 
 galena, the pieces found, seldom of the size of a 
 walnut, are distinctly cleavable, and decomposition 
 coats them with a white meally sulphate of lead. 
 
 In extracting lead from the ore, each fodder 
 always supplies from a few grains to 20 oz. of 
 silver, and when the quantity warrants the expense, 
 it is separated by the refining process, or cupel- 
 lation ; the lead by the flame gradually vitrifies, 
 and either sinks into the test or is blown off, 
 leaving the silver unaltered. The lead is converted 
 into Litharge (L. 3 + 2 Ox.), which at first coheres 
 in masses, but on exposure to the atmosphere 
 separates into fine scales, partly red and partly 
 golden-yellow, consisting of yellow oxide or massi- 
 cot, combined with about 4 per cent, of carbonic 
 acid. 
 
 The reciprocal combinative potencies of metallic 
 sulphurets and litharge need consideration. Accord- 
 ing to the nature of the sulphuret will be the quantity 
 of litharge required, from 5 to 30 volumes, to cause 
 sulphurous acid gas to evolve, and either solicit the 
 metal left to combination, or it remains as an oxide 
 with the undecomposed portion of litharge. When 
 the litharge is minus, of course its potency effects 
 
340 CHEMISTRY OF POTTERY. 
 
 only a portion of the sulphuret, and becomes 
 sulphuret of lead, a very fusible alloy remaining. 
 
 Until very recently chemists supposed that 
 lead and cobalt would not combine by fusion, 
 although the blue-printed ware with lead-glaze 
 might have suggested the contrary. But a direct 
 combination has been effected by Gmelin, by rolling 
 cobalt-powder up in a sheet of lead in different 
 proportions, from 1 cobalt and 1 lead, to 1 cobalt 
 and 8 lead, then covering the compound with 
 charcoal to exclude the air, and raising the tem- 
 perature to fusion of all. 
 
 Observing a fragment of cream-coloured ware 
 on which the lead-glaze had run into a yellowish- 
 green glass, I broke it for examination, and found 
 numerous globules of lead in a reduced state ; a 
 remarkable crazing of the upper surface was pre- 
 sented, yet not at all in the portion immediately 
 in contact with the body. Must we suppose that 
 the expansion of the glaze had been regulated by the 
 expansion of the biscuit, and its contraction was in 
 accordance on cooling ? 
 
 When a high temperature is given to lead in a 
 glass retort on the commencement of fusion, the 
 fusing portion is a bright yellow, and the other a 
 dirty pale brick-red powder, and in a platinum 
 crucible the resulting colours are the reverse. 
 When lead is thus fused in the air a powder, 
 Lead Ashes, is formed a mechanical mixture of 
 metallic lead with the protoxide, or massicot, which 
 vitrifies into a greenish glass, with globules of lead 
 present. The fusion of red oxide needs care, to 
 prevent there remaining globules of metallic lead, 
 
METALS. 341 
 
 or the frit having a dark-brown tint. With much 
 momentum the oxides of lead fuse, vitrify, and lose 
 weight ; the surface of the crucible is glazed with a 
 yellow glaze, like some coarse pottery ; and unless 
 precaution is employed, some of the oxide may be 
 dissipated. 
 
 Vanadiate of lead with phosphate of soda forms 
 a beautiful emerald-green assay, in excess with 
 borax, deep blue ; could not some modification of 
 these supply additional colours to the palette ? The 
 native mineral is chlorine 2 *3, lead 7, protoxide of 
 lead 66*3, vanadic acid 23 '5, peroxide of iron, and 
 silica 163 - 99*463. 
 
342 CHEMISTRY OF POTTERY. 
 
 MANGANESE. 
 
 THE grey, black, brown, or reddish-white ores 
 and carbonate of this metallic substance seem more 
 diffused over the crust of the globe than those of any 
 other, iron excepted, and have been during a long 
 period employed to correct the impurities of fusing 
 glass. Boyle was the first discoverer of it in 
 England, though since his time many others have 
 done so. Its great momentum in soliciting oxygen 
 prevents its occurrence in the metallic state except 
 with arsenic and sulphur. The article supplied by 
 commerce always occurs in nature as an oxide, with 
 different proportions of the dose of oxygen, yet 
 without acidifying those with the maximum. Ac- 
 companied by carbonate of barytes, sulphate, muriate, 
 and carbonate of lime, oxides of copper, lead, and 
 iron, as indicated by soliciting the magnetic potency, 
 the mineral is ponderous, with an earthy texture, 
 amorphous and crystallised in prisms, tetrahedral, 
 rhomboidal, or striated. The manganese of com- 
 merce is often contaminated with carbonate of lime. 
 
 Process. Wash well in water 15, test 25, two parts ; filter out, 
 wash well, and evaporate dry. To liquid add test 7, to show the 
 amount of lime. 
 
 Analyses. 1. In dilute nitric acid separate the foreign ingre- 
 dients usually present in the ore of manganese ; decant the liquid, 
 and on a filter dry the residuum ; this digest one hour in concen- 
 trated muriatic acid (12 Beaume), then add carbonate of soda 
 until no more white precipitate appears ; this incandesce and it will 
 become black. Or 2. Muriatic acid with raised temperature satu- 
 rate with ore of manganese, and spice with test 25 ; evaporate half 
 
METALS. 343 
 
 of the liquid, add pure water, and then test 1, while any precipi- 
 tate appears ; during twenty-four hours immerse test 41, to cause 
 deposit of the copper ; which filter out, and add test 1 till pre- 
 cipitation commences ; by test 8 precipitate the iron ; repose 
 twenty-four hours ; add sulphate of soda when lead is suspected 
 to be present. By test 5 precipitate any copper remaining, and 
 digest in test 2. When the iron is abstracted, add test 2, and the 
 precipitate will be oxide of manganese. Or 3. To the muriatic 
 solution add test 5, wash the precipitate in test 2, dissolve it in 
 test 24; alkalinise by test 3, digest thirty-six hours, and filter ; add 
 test 16, filter out and wash well the precipitate. Or 4. Mix black 
 oxide of manganese 2, and test 34 ; fuse one hour, cool, dissolve 
 the calc in distilled water at 212 ; filter, evaporate, crystallise, and 
 in a covered crucible calcine the crystals. Or 5. In water triturate 
 the residue of the retort after the oxygen has evolved, or oxalate 
 of potash and black oxide of manganese ; add plenty of pure 
 water ; and by test 2 precipitate, filter, dry and ignite. 
 
 The peculiar metallic nature of this mineral was 
 more than the skill of Bergman could develop ; 
 neither were the efforts of Scheele successful ; but 
 in 1774 Gahn adopted a process by which he 
 accomplished the object of his research : 
 
 Process. Line a crucible w r ith charcoal powder moistened with 
 water ; place therein a ball of the pulverised mineral agglutinated 
 with linseed-oil ; surround and cover with charcoal powder ; over 
 this lute another crucible ; raise the temperature extremely 
 high, and continue it eighty minutes ; leave to cool ; and at the 
 bottom will be a number of metallic globules, usually about one- 
 third the weight of the quantity of mineral employed. 
 
 I think every intelligent person will remark here 
 the true cause of reduction : in the charcoal the 
 oxygen evolved from the oxide became fixed, and 
 the reduced metal remained in the crucible. Dr. 
 Turner first detailed the chemical peculiarities, and 
 
344 CHEMISTRY OF POTTERY. 
 
 it is now well understood, that when the tempera- 
 ture of the bin-oxide (the Black Wad of the Upton- 
 Pyne mine) is raised, one-fourth of the oxygen 
 present evolves ; and from pure ore, this is to the 
 amount of 9 per cent., or one- eleventh of the 
 weight. The three oxides have these proportions 
 of components : 
 
 Protoxide. Binoxide. Red oxide. 
 
 Manganese 86-940 ... 97'835 ... 99-242 ... 98-098 
 
 Oxygen 9-851 ... ... ... 0-215 
 
 Water 0-949 ... 1-120 ... ... 0-435 
 
 Barytes 2-260 ... 0-532 Iron 0-130 ... O'lll 
 
 Silica truce 0'513 . 0*840 , 0'337 
 
 100-000 100-212 99-196 
 
 Manganesium is without savour or odour ; has a 
 whitish-grey colour, like cast-iron ; fine granulated 
 irregular texture, uneven fracture ; metallic bril- 
 liance, soon tarnishing by the action of the atmo- 
 sphere ; specific gravity 8'013, softer than cast-iron, 
 and readily filed ; so extremely brittle it cannot be 
 extended by the hammer, nor drawn out into wire ; 
 its tenacity consequently is not known ; it surpasses 
 all other metals in combustibility ; though less fusible 
 than iron it is a very refractory metal, requiring a 
 temperature equal to 160 Wedgwood for complete 
 fusion ; whenever iron is present, the magnet will 
 indicate it ; and hence this is the test of the purity of 
 manganesium ; it can be protected from oxidation by 
 immersion in alcohol, or oil ; but unless thus pro- 
 tected, such is the momentum of combinative potency 
 with which it solicits oxygen, that its lustre readily 
 
METALS. 345 
 
 fails, the colour quickly becomes red, violet, brown, 
 and black, and in a much shorter time when ex- 
 posed to the atmosphere during the rise of tempera- 
 ture ; and in this condition rapidly decomposes most 
 metallic oxides ; and, in its separating water into 
 elements, the hydrogen is affected by the metal, 
 and the noisome odour of assafoetida evolves ; it also 
 similarly separates sulphuric acid, but is separated by 
 nitric acid. When present in an alloy of gold, silver, 
 or copper, brittleness of the whole ensues. Its great 
 combustibility, and combinative potency with iron, 
 are most useful in the Manufacture of glass ; as all 
 impurities are appropriated by these, and during the 
 raised temperature are brought to the surface, off 
 which they are skimmed. It is fusible with the 
 earths, and the degree of oxidation varies the tint of 
 the calc, brown, violet or red. 
 
 The peroxide is found at Upton-Pyne mine, near 
 Exeter, and also near Nuneaton, in Warwickshire, 
 a few miles distant from Coventry. This mine pro- 
 duces two species of ore, not always kept separate, 
 in the mean : 
 
 Protoxide 81'12 2 atoms binoxide 
 
 Oxygen 13'48 2 ditto susquioxide 
 
 Water 5'40 1 ditto water; 
 
 their specific gravities, however, are black 4*531, 
 brown 4 '336 ; the latter is more pulverulent than 
 the former ; and at the usual state of incandescence 
 evolves lO'l per cent, of water ; the other 5*725 
 water, and 7*385 oxygen gas. When pure, it has 
 a radiated texture, dark steel-grey colour, with a 
 beautiful lustre ; it is brittle, very soft, and soils the 
 
H46 CHEMISTRY OF POTTERY. 
 
 fingers ; specific gravity 47563. When kept in a 
 state of incandescence, rather more than one- tenth 
 of the weight evolves in oxygen gas, the residuum 
 being a brown powdery calc, devoid of metallic 
 lustre. 
 
 Hitherto there has not been suitable attention to 
 these oxides. The readiness with which they com- 
 bine with earths, and promote their fusibility in a 
 state of high temperature, renders them very useful 
 in the Mocha and dipped ware. The colorific pro- 
 perty suffers during the evolution of carbonic acid 
 gas from carbonaceous components, till all the gas is 
 dissipated, and then it can be restored (or may be 
 protected) by the presence of nitrate of potash, which 
 supplies a suitable dose of oxygen. 
 
 Processes. (1.) In distilled water wash well some manganese 
 in powder ; evaporate dry ; add half the weight of muriate of am- 
 monia, and during twenty minutes incandesce highly ; during this 
 raised temperature the chlorine will be solicited to combination 
 with the metal only, and the compound may be dissolved in water 
 by careful washing. Add test 4, filter out the precipitate, place 
 this in a green glass tube, and pass through this a current of 
 hydrogen gas ; the result will be the Protoxide, of an olive-green 
 colour, when subjected to the action of the atmosphere. 
 
 (2.) (Forchhammer s beautiful light green.) In an open porce- 
 lain tube incandesce some grey ore of manganese ; pass a stream 
 of hydrogen gas through the tube, and the oxide will appear 
 primrose-yellow ; quickly take out of the tube, and put into a 
 phial, which stop close, and it will become a beautiful green, but 
 the oxygen of the atmosphere would cause it to become brown. 
 Dry sulphate thus treated will supply a permanent light green. 
 
 (3.) Incandesce deutoxide, or carbonate of manganese, half 
 an hour or more ; or the muriate evaporate dry, and in a closed 
 vessel incandesce the like time for the Red oxide. This will 
 combine with bases, as 6 M. + 1 base. 
 
METALS. 347 
 
 (4.) (Turner's.} The residuum of the retort, after obtaining 
 oxygen, mix with a sixth part of its weight of powdered charcoal ; 
 incandesce highly during thirty-five minutes ; dissolve in muriatic 
 acid, evaporate dry, and raise the temperature to fusion, which 
 keep up not less than two hours ; dissolve in pure water, filter ; 
 add test 8, and filter out the lime ; to the liquid add test 4, filter, 
 and wash well ; form a vacuum with sulphuric acid, and dry 
 therein ; then dissolve in sulphuric acid, and the solution will be 
 colourless. 
 
 (5.) To separate metallic oxides . Muriatic acid saturate with 
 the ore, then add one-sixth of nitric acid, evaporate one-fourth, 
 then add three volumes of pure water ; alkalinise with test 1, and 
 immerse test 38 twenty-four hours to separate the copper present ; 
 filter ; add test 1 to the liquid till it appears turbid ; alkalinise 
 with test 8 till precipitation ceases ; then let repose twenty-four 
 hours ; add test 28, filter out the lead ; add test 5, filter out and 
 wash well the copper with ammonia and water ; the precipitate dis- 
 solve in test 24, add test 3, then digest one hour, filter and wash. 
 
 (6.) The ore dissolve (as in 5), filter, wash well with four 
 volumes of cold pure water ; alkalinise with test 2 (to blue the 
 test-paper just red by acetic acid) ; filter out and wash well the 
 iron, evaporate dry, wash well, again evaporate, and incandesce to 
 dissipate test 26, and the calc is pure manganese. Or, 7. The 
 cold acid solution alkalinise with test 2, filter quickly ; let the 
 brown turbid liquid repose twenty-four hours, decant ; evaporate 
 the precipitate ; also all the liquid evaporate dry for the oxide. 
 There is much care needful, and also three or four filters, to 
 quickly pass the liquid, and prevent any portion of the manganese 
 in solution being deposited on the filter with the iron and earths. 
 
348 CHEMISTRY OF POTTERY. 
 
 PLATIIS 7 UM. 
 
 THE metal thus named by the Spaniards, 
 because of its colour resembling that of silver, has 
 been known to Europeans only since 1749. Like 
 gold (to which, with all the advantages, it is equal 
 in some, and superior in several other valuable 
 properties, as for the fabrication of instruments, 
 vessels, and utensils, even for domestic economy, 
 as well as for researches in Natural Philosophy, 
 Chemistry, and the Arts) it is supplied by Nature 
 in only a metallic state, yet always accompanied by 
 various other metals ; chiefly from Choco and Santa 
 F6, in South America, in crude small flat grains, 
 with a silvery lustre. The largest known specimen, 
 found in the Ural Chain in 1827, near the Denu 
 Doff mines, is the size of a pigeon's egg ; its 
 weight is rather more than 9i Ibs., and is preserved 
 in the museum of the Royal Society at Bergara ; 
 prior to that time the largest known mass was 
 11,641 grs. at Madrid, from Condoto. It is found 
 in South America, Brazil, St. Domingo, Siberia and 
 the Ural Chain. The ore is exceedingly impure, 
 owing to the presence of nine other metals, four of 
 which, palladium, irridium, osmium, and rhodium, 
 are new, the productions of the laboratory ; and, in 
 addition to iron and chrome, are three others- 
 copper, antimony, and lead. In the autumn of 
 1806 Vauquelin discovered platinum ore to the 
 amount of 10 per cent, in the silver ores of Guadal- 
 canal, in Estremadura (much like the grey copper 
 
METALS. 349 
 
 ores, the fahlerz of the Germans), in a gangue of 
 quartz, carbonate of lime, and sulphate of barytes ; 
 in the company of lead, copper, antimony, iron, 
 silver, sulphur, and arsenic ; always entirely free 
 from the four metals present with the ore from 
 South America, and constantly among the sulphur 
 and silica of the gangue. It is proved to be an 
 accidental, not an essential component of the ore, by 
 its very irregular distribution, from less than one 
 to more than ten per cent., and with the silver from 
 two to twelve per cent. 
 
 Process. In nitre-muriatic acid (see gold, p. 328), with as 
 little rise of temperature as will answer, dissolve the metallic 
 grains. A portion of black matter will remain indifferent to the 
 potency of the acid ; decant off this the liquid, and into it 
 carefully drop test 34 ; the orange-yellow precipitate filter out, 
 wash well, evaporate dry, and then raise till incandescence 
 commences, to expel the acid and alkali, and reduce the metal in 
 an agglutinated state. Eepeat the process, and the metal will be 
 obtained pure. The powder or grains are next wrapped up in 
 strong platinum foil, then incandesced, and by great pressure, or 
 cautious hammering, they are rendered compact, and formed into 
 an ingot. Or, on a support of strong marie, by the oxy-hydrogen 
 blow-pipe fuse a few grains, to which while in fusion keep 
 regularly adding a few more, until about one ounce is fused, 
 when more in quantity may be added, until any required size of a 
 piece is obtained ; cut off the small part next the support, because 
 with it will be present a spice of silica, that might deteriorate foil, 
 wire, etc. 
 
 Platinum thus obtained, pure or refined, is the 
 heaviest substance known. Its specific gravity, from 
 the ammonia, chloride reduced by heat, is 21*5, arid 
 is by hammering increased to 21-5313. It is with- 
 out savour or odour, with hardness between copper 
 
350 CHEMISTRY OF POTTERY. 
 
 and iron, considerably greater than gold or silver ; 
 with a white colour, to the eye like that of silver, 
 but deficient in brilliance, and on the touchstone the 
 two are not distinguishable ; it is very malleable and 
 ductile ; it can be hammered into foil of remarkably 
 thin leaves, useful in analytic processes, and it can 
 be drawn into wire not exceeding j~ of an inch in 
 diameter. Dr. Wollaston inclosed a thin wire of 
 platinum in a fine tube of pure silver, and after this 
 had been drawn out in wire to an extremely fine 
 state, he digested the wire in nitric acid, which 
 dissolved the silver, and left platinum wire not 
 thicker than ~ of an inch. Its tenacity is such 
 that a wire 0*078 of an inch in diameter will support 
 274'31 Ibs. avoirdupois. Alone it is indifferent to 
 the potency of the most concentrated acids singly, 
 however high may be the temperature as it also is 
 to fusion in usual temperatures so that the above 
 is the only method of obtaining it in quantity. 
 Alloyed it is fusible at a moderate temperature. 
 When at a bright incandescence, two plates or rods 
 can have their particles so welded together, like 
 iron, as not to present the least appearance of having 
 ever been separate. It is indifferent likewise to the 
 action of air and water. The highest temperature of 
 the furnace fails to excite combination of oxygen and 
 pure platinum into an oxide, although it is sufficient 
 to partially oxidate the metal from South America, 
 because of the presence of iron, etc. But a better 
 acquaintance with the metal will suggest the proper 
 heat for accomplishing the purpose. 
 
METALS. 351 
 
 Processes (1.) To obtain the Protoxide. With pure water 
 boiling hot dilute the solution of muriate of platinum ; add test 
 20, filter out, wash well the coloured precipitate of chloride of 
 mercury and protoxide of platinum ; volatilise the chloride ; the 
 black protoxide left incandesce, and from 100 grains will evolve 
 12 \ cubic inches of oxygen, or with lamp black, 12 cubic 
 inches of carbonic acid gas, and the metal is reduced. On 
 enamels this will not suffer under the highest temperature of the 
 muffel. 
 
 (2.) For the Peroxide. To the solution, as above, add 
 excess of test 24, distil this excess over; alkalinise with test 1, 
 and the reciprocal potencies of the two substances will be obvious 
 as remarkably strong, in the brown bulky almost insoluble triple 
 salt which precipitates ; filter out, wash well, dry, and raise the 
 temperature till it becomes a brown or black powder ; or when 
 very high, is reduced because of the oxygen evolving. It 
 dissolves with the caustic or carbonated alkalies, 1 and 2, also 
 it combines with the alkaline bases, 5, 6, 7. 
 
352 CHEMISTRY OF POTTERY. 
 
 SILVER. 
 
 THIS metal is recorded as being known by the 
 earliest society, and almost as soon as gold. In its 
 native state it occurs in Huel Duchy and Huel 
 Mexico, Cornwall, the mining districts of Saxony 
 and Bohemia, but principally in Peru and Mexico. 
 It is without savour or odour ; the colour, a fine beau- 
 tiful white, with a slight yellowish tinge, and brilliance 
 equal to that of any other metal except perhaps 
 polished steel ; it is harder than gold, but softer than 
 copper ; its specific gravity in cast bars 10*474, in 
 hammered plate 10 '5 10 ; its malleability is only in- 
 ferior to gold, and it is beaten into leaves only 
 ^55-555 of an inch thick ; its ductility allows it to be 
 drawn out into a wire much finer than a human hair, 
 so that a grain can be extended 400 feet ; its tenacity 
 in a wire 0*078 of an inch in diameter supports 
 187*13 Ibs. avoirdupois. It does not suffer from im- 
 mersion in the water; neither does it oxidate, although 
 it tarnishes, in the air, at ordinary temperatures ; but 
 when raised to incandescence its brilliance much in- 
 creases, and the metal fuses at 22 Wedgwood ; during 
 this state, in an open crucible, it solicits oxygen from 
 the atmosphere, and becomes a greenish-brown oxide 
 (Silver 1+1 Oxygen), and raised temperature causes 
 the metal to boil and volatilise ; but when in fusion, 
 gradual diminution of the temperature renders the 
 surface crystalline, and when this is congealed, by 
 pouring out part of the fluid metal, may be obtained 
 large crystals insulated, and in groups of four-sided 
 pyramids. 
 
METALS. 353 
 
 Processes. (1.) In nitric acid, at 12 Beaume, dissolve 
 240 grains of standard silver ; filter, add distilled water till the 
 whole weighs 960 grains (2 ounces, or 1 silver + 3 aciduline 
 solvents). This will cause the particles of the silver to be in 
 a state so very comminute as to be readily, and without loss,, 
 separated in the precipitate. Stir well and often, with test 40, 
 and leave it immersed 24 hours ; when all the silver is precipitated 
 decant the supernatant liquid, wash well the precipitate, boil it 
 a few minutes in ammonia, to appropriate whatever spice of 
 copper is present, filter, wash well on the filter, and evaporate 
 dry, the Pure Silver. Or, 
 
 (2.) From a fresh supply of crystals form test 17, with which 
 treat the nitric solution, and in 36 hours there will be a precipitate 
 of sulphate of silver, with a superstratum of sub-oxysulphate of 
 iron. This latter decant off, and separate all the muriate of silver 
 presented by careful levigation of it in a solution of common salt. 
 
 (3.) To the nitric solution add lime-water, filter out and wash 
 well the dark greenish- brown precipitate, which is without savour 
 or solubilty in water ; it is readily soluble in nitric acid, and at 
 the proper temperature resumes the reguline state, or that of 
 metal ; dissolves in ammonia exposed to the air, and a brilliant 
 pellicle forms, which, being dried, is the black oxide. Silver 1 
 + 2 oxygen. 
 
 (4.) Chloride. To the nitric solution add common table -salt 
 until precipitation ceases ; wash well this curd, and then evaporate 
 dry. This compound is one of those least soluble, needing 3072 
 parts of pure water for solution. The action of the atmosphere 
 causes it to gradually assume a purple tint. At a temperature of 
 500 Fahrenheit it fuses, and, on cooling, assumes the grey semi- 
 translucent appearance called horn silver. The chloride is soluble 
 in ammonia, and the result is fulminative ; it is indifferent to pure 
 alkalies, yet by carbonated alkalies it is solicited to separation, 
 and any (but only) substances with hydrogen present will separate 
 the chlorine. Silver 1 + 1 chlorine. 
 
 Only singular good fortune, and some skill of the operator, 
 can always obtain the silver pure, and supersede failures from two 
 causes : one, the uncertainty of the temperature ; as when this is 
 too high the chloride volatilises ; and when it is too low there is 
 not complete reduction. The other is, when high temperature is 
 applied to this alone, the metal permeates the pores of the crucible 
 and is lost. The easiest process is to use an iron pot, into which 
 
 2 A 
 
354 CHEMISTRY OF POTTERY. 
 
 put plenty of distilled water, a few pieces of iron, or fresh turned 
 iron chips, also the chloride, and boil till all the silver is reduced. 
 Some persons form a paste of the chloride and four times its 
 weight of potash or soda moistened with water, and this is fused 
 in a crucible well lined with alkali. 
 
 (5.) Goettling's. To separate Silver from Copper. Deter- 
 mine the weight of the metal, as 1, and put it into a matrass ; 
 add test 24-, 10, and water 5 ; keep in a high temperature of a 
 sand bath, and frequently stir with a glass cane during three 
 hours, then add boiling water, 6 bulks, continuing the heat ; in a 
 coarse linen bag put some clean copper turnings, which introduce 
 into the matrass, and boil four hours ; filter out the precipitated 
 pure silver, and wash till the washings are indifferent to the 
 alkaline potency of test 2 ; then reduce to a button, if needful. 
 The liquid and washings evaporate till a pellicle appears, then 
 crystallise the sulphate of copper. 
 
 (6.) Mix together glass powder 2, potash 1, nitrate of potash 
 2, and grain silver 8 ; this mixture put in a crucible twice the 
 size usually employed for such a quantity, and over this invert and 
 lute well a smaller crucible with the bottom perforated; place them 
 in a furnace whose temperature will just fuse the silver ; surround 
 and almost cover the crucibles with charcoal ; keep the tempera- 
 ture steady until a hot coal, held over the hole of the upper 
 crucible, neither becomes more brilliant, nor causes a hissing 
 noise ; raise the temperature very high, quickly, and after 20 
 minutes take the whole out, cool, break the under crucible, and 
 from the scoriaceous mass take the button of pure silver. 
 
 (7.) Dizes. To separate Silver from Gold. When silver 
 is present with gold, in twelve hours it deposits as a black muriate 
 in the nitro-muriatic solution. In a platinum crucible, whose 
 cover has [a small perforation, add to the metal twice its weight 
 of sulphuric acid, and raise the temperature to 180 Fahrenheit 
 eighteen hours ; then decant into a porcelain dish, and add two 
 bulks of pure water, and let the fluid repose twenty-four hours or 
 more. By siphon abstract the liquid from the brown precipitate, 
 or gold, which throw upon a filter and wash with hot pure water. 
 Into the decanted liquid immerse slips of polished copper, and 
 when no more silver can be thereby obtained, as deposit or 
 precipitate, wash it all well, and fuse it with charcoal in a 
 crucible. The gold fuse with nitre, which separates the copper, 
 and the solution of sulphate of copper evaporate and crystallise. 
 
METALS. 355 
 
 TIN. 
 
 THIS metal was well known at a very early 
 stage of society, and, in more recent times, it was 
 the Jupiter of the alchemists. So seldom has it 
 been found, that its existence in a native or pure 
 state has been questioned. As Tin Stone, or native 
 oxide of Tin, which supplies most of the metal for 
 commercial purposes, it occurs in primary rocks 
 only, massive, crystallised, and disseminated, in 
 veins ; and when the texture is fibrous, the variety, 
 found only in Cornwall, is named Wood Tin Ore. 
 It is also found as a sulphuret, with a little copper 
 and iron, called Tin Pyrites, of a yellowish -grey 
 colour, with metallic lustre, fibrous or laminated 
 texture, and prismatic irridescence. It is found in the 
 mines of Bohemia, Saxony, the Isle of Banca, the 
 peninsula of Malacca, Fahlun, the East Indies, Chili, 
 and Massachusetts ; yet in large quantity is it found 
 only in Devonshire and Cornwall. Wherever it is 
 found there certainly is plenty of it ; but, compara- 
 tively, it is the most rare of the metals longest 
 known and commonly used. Before any dates of 
 authentic history, Cornwall supplied it, as the 
 merchants of Tyre thence obtained it prior to the 
 days of Moses, and in subsequent or contemporary 
 times the Greeks obtained it from the IKTLS or depot 
 on St. Michael's Mount, and by these it was 
 supplied to any and all purchasers in the then 
 known world. 
 
 Tin has a beautiful yellowish silvery-white 
 2 A 2 
 
356 CHEMISTRY OF POTTERY. 
 
 colour, and in its newly-formed state is very 
 brilliant, rather impalatable savour, and when 
 rubbed a very peculiar odour. The hardness of the 
 mineral is between that of felspar and rock-crystal, 
 and that of the metal between gold and lead ; the 
 specific gravity is 7*291, raised by hammering to 
 7 '299. It has little sonorosity, but crackles remark- 
 ably when bended, and is very flexible ; its malle- 
 ability is such as to form beneath the hammer 
 extended leaves called Tin foil, about ^ of an inch 
 thick, and was it for purposes of commerce needed, 
 might be reduced to less than half this thickness. It 
 has less ductility and tenacity than any of the other 
 seven usual metals ; a bar \ of an inch diameter 
 breaks by a weight of 296 Ibs., and a wire ^ of an 
 inch just supports 47 '20 Ibs. avoirdupois ; or accord- 
 ing to Morveau, a tin wire 0*078 inch diameter 
 just supports only 34*7 Ibs. The atmosphere soon 
 changes the brilliant lustre into a blackish-grey, 
 which remains without further alteration from the 
 weather, or immersion in water ; but the action of 
 very hot steam passing over red-hot tin quickly 
 oxidates the metal, and the hydrogen of the steam 
 is liberated. It fuses at the temperature of 442 
 Fahrenheit, and when slowly cooled crystallises into 
 a rhomboidal prism. It resembles lead in being 
 very brittle at a temperature of 380, and when 
 then broken by the stroke of a hammer, it presents 
 a texture fibrous or grained. It is granulated by 
 quickly agitating the mass during the time of its 
 transition from the fused or fluid to the cold or solid 
 state. Its purity is in exact ratio with its levity, 
 while that of gold accords with its density. 
 
METALS. 357 
 
 Processes. (1, 2, 3.) Pure Grey Protoxide. In hot 
 muriatic acid dissolve grain tin ; or in aqua-regia of nitric 
 acid 1, muriatic acid 2, add only bits of tin in succession, one 
 after another is dissolved, preventing loss from effervescence and 
 raised temperature ; the liquid alkalinise with test 1 ; the white 
 precipitate or hydrate is partially re-dissolved, but the residue, 
 left to repose, becomes a dark grey powder, with even a metallic 
 lustre. The white powder heat to 300 to evaporate all the water, 
 and the result is a dark grey oxide, without savour, soluble in acids 
 and alkalies, and at 448 ignites and burns like tinder, becomes 
 cream-coloured, and is converted into peroxide, which may be 
 crystallised ; and at 550 some of the oxygen evolves, and the 
 metal is reduced. It also, when in solution, solicits oxygen from 
 the atmosphere, and becomes the peroxide. 
 
 (4.) Expose the tin of commerce to a moderate heat in an open 
 vessel ; regularly skim off the surface the grey powder which forms 
 successively ; this impure powder afterwards keep at 400, until 
 all becomes the greyish- white protoxide, or pure Tin Ashes, an 
 oxide more refractory in high temperatures than that of any other 
 metal ; and hence so useful in forming the opaque glaze of cream- 
 coloured ware, and the white enamel. 
 
 (5.) Berard's Method. (Pure Chloride.) Into shallow 
 dishes or saucers put the granulated Tin, and cover with 
 muriatic acid, at 12 Beaume ; the offensive gas will be a 
 compound of arsenic and hydrogen, and afterwards of hydrogen 
 only ; after 20 minutes pour off the acid into a vessel for 
 subsequent application. The acid which attaches to the metal 
 will continue soliciting it, hydrogen will evolve, and the 
 atmosphere will promote oxidation. Pour on the acid again, 
 and it w;ll appropriate all the protoxide thus formed ; and when 
 a sufficient quantity of acid is employed, by pouring it off one 
 portion of metal upon another, and allowing about two minutes to 
 each, in succession, through the whole series, a solution of proto- 
 muriate of tin, for making purple, is obtained very quickly and 
 most economically. 
 
 (6.) To concentrated nitric acid add granulated tin, very 
 carefully preventing loss by the ebullition while the temperature is 
 raised ; during the violent effervescence the tin, as a white powder, 
 of peroxide, deposits at the bottom of the vessel, and assumes 
 a very light yellow tint, when acid and water are expelled by 
 
358 CHEMISTRY OF POTTERY. 
 
 raised temperature. Another peroxide, with like properties to 
 this, is obtained by distilling tin tilings and red oxide of mercury. 
 
 (7, 8.) In nitric acid dissolve grain tin, precipitate by 
 ammonia, filter; to dissolve most of the tin digest filter and 
 contents in cold muriatic acid ; again filter, and next dissolve 
 filter and contents in warm concentrated muriatic acid. Add test 
 9 for any iron present. Or, in dishes (as 5) put tin filings, and 
 cover with water 90, nitric acid 10, 48 hours. 
 
 (9.) In a tabulated retort, to muriate acid two parts add one 
 of tin ; slowly raise the temperature, and when the solution is 
 finished add more acid and carefully decant into a well -stoppered 
 phial ; a black protoxide of copper is often left in the bottom of 
 the retort. 
 
 The oxides of Tin have peculiar potencies in 
 combining with other substances which they solicit, 
 similarly, though with less momenta than acids. 
 The peroxide does not dissolve in, but combines 
 with, muriatic acid, and forms a compound soluble 
 in water, as is that formed by the combination when 
 digested with potash ; and when the solution is 
 evaporated a yellow jelly results, also soluble in 
 water. With sulphuric acid, similarly to most 
 metallic oxides, it combines into a compound not 
 soluble in water, only the acid appropriates the 
 water. 
 
METALS. 359 
 
 ZINC. 
 
 THIS metal has not hitherto been discovered 
 native in Europe, and its reduction from the ore is 
 of comparatively recent practice. The ancients, di- 
 rected by the practice of Cadmus, formed brass by 
 mixing with copper a mineral which had much zinc 
 present ; but they did not possess a knowledge of the 
 reduced metal, which was first imperfectly described, 
 about 1270, by Albertus Magnus, and the name was 
 first used, in 1536, by Paracelsus. 
 
 The most common ore of zinc is Blende, a 
 foliated brown unsavoury mineral, insoluble in water, 
 with specific gravity 4. The principal works for the 
 reduction of the sulphuret are at Swansea and Bristol. 
 The mineral is roasted, then pulverised and mixed 
 with charcoal, and put into very large crucibles ; these 
 are carefully closed, the temperature is raised very 
 high, the metal falls to the bottom of the pot, and 
 escapes through an iron tube into a vessel of water, 
 from which it is taken and melted into ingots, the 
 Speltre of commerce, so much in demand for the 
 brass foundries of the north. 
 
 Too frequently this is a mechanical compound of 
 zinc, lead, sulphur, and charcoal, the last in a small 
 proportion, remaining even after careful distillation ; 
 but when it has the specific gravity 6*861 to 7*1 cast, 
 or 7'1908 hammered, it is regarded as best for the 
 Arts. Zinc, in this condition, seems composed of 
 many thin adhering plates, rather soft, with a bril- 
 liant slight bluish-white colour, unpleasant savour, 
 and peculiar odour, and rubbed a little between the 
 
360 CHEMISTRY OF POTTERY. 
 
 fingers supplies a blue tint. Its little ductility allows 
 it to be with care drawn out into wire, and its tena- 
 city is that which in a wire of Atli of an inch just 
 supports 26 Ibs. It connects the brittle with the 
 malleable metals, differing as much from antimony 
 and arsenic as from copper, lead and tin. The 
 hammer renders it flatter, without breaking, and 
 cautious, equal pressure reduces it to thin, supple, 
 elastic plates, which break by folding. 
 
 At the ordinary temperature the atmosphere 
 soon tarnishes but does not further change the surface 
 of the metal, and a current of air seems needful to 
 its slow oxidation ; but when beneath water, soon is 
 the surface black by the oxygen solicited from the 
 water, leaving the hydrogen to evolve ; with raised 
 temperature decomposition is more rapid, and is yet 
 further increased by exposure to a current of steam. 
 
 At the temperature of 220 it becomes malleable, 
 and without breaking may be hammered into very 
 thin plates ; or, when this temperature has been long 
 continued, it may be either passed through rollers, or 
 easily turned in the lathe ; and at 400 is pulverulent 
 in a mortar ; at 680 it melts, and slowly cooled forms 
 masses of quadrangular prism crystals, disposed in 
 every direction, which gentle heat renders a change- 
 able blue colour ; and at 750 it volatilises in close 
 vessels. 
 
 Zinc melted in an open vessel soon solicits 
 oxygen from the atmosphere, and covers the surface 
 with a grey pellicle, which being removed is suc- 
 ceeded by another till all is oxidated into a powder 
 without savour, insoluble in water, and useful as a 
 water colour, but readily soluble in acids, forming 
 neutral salts. When the results of the pellicles are 
 
METALS. 361 
 
 fused and agitated in an open vessel, soon is formed 
 a yellowish-grey oxide. This projected into a cru- 
 cible or deep pot at incandescence has a brilliant 
 white flame, and emits flowers of zinc, very light and 
 white flakes of oxide, zinc 1 + 1 oxygen, and this when 
 spiced with carbonic acid is no longer volatile, but at 
 a high temperature fuse* into glass. 
 
 The reduction of oxide of zinc is difficult, be- 
 cause only by mixture with charcoal, and a long con- 
 tinuance of the temperature of a biscuit oven, or 
 glass furnace, in a well-closed crucible, is diminished 
 the momentum of its combinative potency with 
 oxygen, and the prevention of its further energy. 
 
 That portion of Calamine with finer grain and 
 texture than chalk, but otherwise much resembling 
 it, is Dicarbonate of zinc, indifferent to carbonate of 
 soda, but fusing with borax and phosphate of soda 
 into a clear colourless glass. 
 
 Sulphuric acid with much momentum solicits 
 zinc to combination, separating it from any impurity 
 of charcoal, iron, and lead, during which hydrogen 
 evolves, holding a portion of the metal in suspension, 
 and which gas promotes the fusion of platinum, not 
 effected by pure hydrogen. When the metal is in 
 solution stir well with test 39, and any metals else 
 will precipitate, and must be filtered out. If the 
 acid be highly concentrated an opaque substance 
 encrusts the bottom of the vessel, much like the 
 German white vitriol ', and less soluble than the crystals 
 resulting from the solution. To the filtered liquid 
 add test 3, filter, wash well, evaporate dry, mix with 
 charcoal powder, ignite, and then with a white heat 
 and porcelain retort distil into a receiver almost filled 
 with water for hydrate of zinc. 
 
362 CHEMISTRY OF POTTERY. 
 
 Having in various and numerous instances de- 
 tailed the manipulative processes of analysis, I shall 
 only add, in concluding this part of the volume 
 that the more the student practises these processes, 
 the better will he be acquainted with the usual phe- 
 nomena of combination. He likewise will find that 
 each resembles a chain, whose continuous links are 
 the several steps of the detail. Aware that success in 
 each depends and results from his first principles, 
 from these he obtains the conditions of his demon- 
 strations ; and whenever incertitude attaches to any 
 result, or however extended and operose may be 
 the steps, he can at pleasure retrace each, or any 
 part thereof, determine its validity, become more 
 convinced on the one hand of the importance, and on 
 the other, of the essential identity of legitimate results 
 of these principles. The means of attaining sound 
 knowledge is thus afforded, and I trust that as such 
 each student will regard and employ them. 
 
THE 
 
 CHEMISTRY OF POTTERY. 
 
 SVNTHESIS AND COMPOUNDS, 
 
 "Good Pottery differs from inferior much less in the number of its 
 Components than in their proper proportions." VAUQUELIN. 
 
 CHAPTER I. 
 
 HISTOEICAL SKETCH OF THE OEIGIN AND 
 PEOGEESS OF THE AET. 
 
 THE Chemistry of Heterogeneous Compounds, 
 because of its advancing several Manufactures essen- 
 tial to national prosperity, in importance has pro- 
 gressed with their extension, and the improvements 
 in machinery during the last sixty years. The 
 partial knowledge current having already accom- 
 plished much, we are warranted in assuming that the 
 dissemination of further and correct information 
 will promote additional improvements, more impor- 
 tant than at present even conjectured, until the 
 Manufactures are advanced to the perfection of 
 
364 CHEMISTRY OF POTTERY. 
 
 which each is susceptible. Only by its being pur- 
 sued with vigour can we keep our country at its 
 high eminence, nor subjected to receive from others 
 that information which so long she has been accus- 
 tomed to communicate. Still, to its peculiar investi- 
 gation an inexplicable indifference has been evinced 
 by the persons most celebrated as original thinkers 
 or experimenters the Daltons, the Faradays, the 
 Henrys, the Brandes, while concerning those condi- 
 tions of the component Atoms which ever remain the 
 same, their observations have excited the attention of 
 the scientific portion of the community. 
 
 The most obtuse intellect will admit that the 
 kindling of fires, baking of bread, preparation of 
 butter and cheese, smithery of metals, and burning 
 of Clay into bricks, are Arts of Life coeval with their 
 wants by the human family. These illustrate the 
 development of man's physical powers to gratify 
 his wishes, yet increase his comforts ; and they de- 
 monstrate that the primeval pair being created per- 
 fect in physical and mental powers, never at any 
 time could all their descendants, the whole human 
 family, possibly become the mutum et turpepecus, the 
 inhabitants of caves, the utterers of inarticulate cries, 
 imagined by Diodorus Siculus, and others who have 
 aspired to the dignified appellation, and sought credit 
 for the high character of philosophers. 
 
 The Manufacture of prepared earths (which 
 otherwise were valueless) into vessels of capacity, 
 and different other subjects, for use, convenience, and 
 ornament, of varied excellence of quality, and con- 
 sequent difference of value, by adequate judges 
 is regarded as useful, needful, and important to 
 
OKIGIN AND PROGRESS. 365 
 
 civilised society, as any other Art of Life requiring 
 the aids of human ingenuity. It is of importance to 
 a nation, because usually the arcana of affluence to 
 ingenuity, industry, and perseverance ; one of the 
 sources of productive employment, or excitements of 
 taste and genius, of part of the population ; a branch 
 of commerce to increase foreign connections, supply 
 correct ideas of political relations, and enrich the 
 merchant ; also a channel of revenue, to increase the 
 power to preserve to the citizens their Rights from 
 infringement, and their Liberties from subjection. 
 It is most intimately connected with Chemistry, 
 surpasses all others in facilities for comprehending 
 Combination by processes of synthesis and analysis, 
 and practising the Manipulations of the Laboratory. 
 Its details involve numerous productions of Nature 
 and Art ; its developments essay to determine by 
 what laws the reciprocal potencies of the component 
 atoms, as well as the masses themselves, of those 
 productions, by chemical changes cause different 
 forms, as either a mere mass, or a beautiful regular 
 and well-defined object. These forms it investigates 
 and scrutinises the better to comprehend the nature 
 and proportions of the components for interesting 
 progressive improvements ; to ensure excellence by 
 the application of scientific principles ; to benefit 
 society by elevating the people in affluence, intelli- 
 gence, and security ; the vantage ground, whose 
 occupancy and appropriation the Manufacturer owes 
 to his country and himself. 
 
 Man in all ages seems to have been the resolute 
 disavower of the authority of common sense, and 
 the willing slave of his imagination. Yet the true 
 
366 CHEMISTRY OF POTTERY. 
 
 philosopher, employing the united faculties of a sound 
 mind, also reasoning on the experience and attention 
 to the operations of the senses as well as the percep- 
 tions of early life, to which he constantly and habi- 
 tually refers whatever is new, whenever similar in 
 any particular, by the powers of memory, feels 
 delight alike elevating and interesting, in contem- 
 plating the immense Laboratory of Nature, directed 
 by Omnipotence, whose fiat determines, with mathe- 
 matical precision, the numerical proportions of 
 Elements in which combinative potency can present 
 the most varied and beautiful phenomena, from the 
 constant reciprocal actions of gas, fluid, and solid, of 
 acid, alkali, earth and metal. 
 
 The contemplation of subjects of human ingen- 
 uity leads the mind to regard the idea of com- 
 mencement, and to reflect on the Inventor of an Art. 
 Tradition and mythology have preserved the names 
 of persons who deserve execration, because of the 
 injuries they inflicted on their species ; and some 
 benefactors of the human race are immortalised in 
 the poetry of the latter, but we fail to obtain data to 
 identify the inventor of this art. Alike over the time 
 and place oblivion has thrown an impenetrable veil. 
 Certainly the probability of any traces of its origin 
 reaching us without interruption seems precluded by 
 the very early and long time prior to any historical 
 records of its products (however rude and to our 
 ideas uncouth) being formed and used. There is a 
 possibility of its having, like many others of the Arts 
 of Life, grown gradually into use, without any direct 
 or sole inventor. The earliest sacred as well as pro- 
 fane histories mention it. But their writers, like 
 
ORIGIN AND PROGRESS. 367 
 
 modern contributors to the stock of literature, fre- 
 quently overlook useful and indispensable subjects, 
 to dilate with ardency on the grand and pompous. 
 In our day of universal spread of correct knowledge, 
 whatever may have been the efforts, they have failed 
 to shake the stigma of disrespect, by Custom irre- 
 movably fixed on the common and most useful Arts 
 of Life the Weaver, Tailor, Shoemaker, Smith ; or 
 to affect the importance attached, because of the value 
 of the products, to the Jeweller, Goldsmith, Sculptor, 
 and Artist, although in favour of the former may be 
 the balance of moral worth against mean cupidity. 
 We therefore may expect the person who had to 
 record the chefs-d'wuvre of workmen " filled with 
 the Spirit of God" (Exod. xxxv. 31, 36), to be indif- 
 ferent to the productions of the Potter,* seen every 
 
 * The real primary force of the word POTTER (as well as its 
 etymon, owing to the mutation of Letters in all adoptions of words 
 into other languages) seems to be connected only with the Hebrew 
 ^TP yotsaar, as employed in Genesis i. 24, 27, 31 ; n. 7, 19 ; 
 v. 1, 21 ; to the forming clay into a human figure, and to the 
 formation of the universe by the Omniscient Chemical Potter, 
 the Infinite Master Mind. The idea of man's being earthy, and 
 originally formed as vessels are by the Potter, or worker in clay ; 
 also the ease with which man, whether an individual, or a nation, 
 can be " broken, even as one breaketh a potter's vessel, which 
 cannot be made whole again," Jeremiah presents in his beauti- 
 ful allegory, xvm. 2-6. All those beautiful and elegant Wares, 
 the most delicate and fragile, which quality some esteem as pro- 
 moting its excellence in a corresponding ratio, or the most durable, 
 which adorn our tables, manufactured with the same elementary 
 components, processes, manipulations and general conformation ; 
 tortured from mineral substances by the agency of acids and 
 temperature in the laboratory ; most just in symmetry, chaste in 
 design, exquisite in fabrication, fine in polish of surface, beautiful 
 
368 CHEMISTBY OF POTTERY. 
 
 day. Another reason why Moses does not even 
 allude to the practice of the Art, and, by implication, 
 to its inventor, may be the constant need for him 
 to combat in the Israelites a proneness to idolatry. 
 He must know that the Egyptian Pantheon consisted 
 chiefly of persons who had conferred on mankind 
 some general and lasting benefit ; he was not ignor- 
 ant who that people regarded as their instructor in 
 this and most of the other Arts ; and that to mention 
 the inventor of POTTING would only again bring to 
 their recollection the idolatrous worship of the in- 
 dividual, Thoth, or Theuth ; Phoenician, Taut ; Greek, 
 Hermes ; Latin, Mercury, the scribe of Saturn, the 
 messenger (gr. a.v yeXos) of the gods, most assuredly 
 a son or a grandson of Noah. 
 
 The solution of the problem, " What kind of 
 earthenware would be fabricated by a colony wholly 
 ignorant of current processes ?" cannot be decided by 
 
 and splendid in enamel, rich, brilliant and tasteful in gilding, 
 remain extremely liable by use to be broken and destroyed. Does 
 any of my readers need to have the parallel presented before him ? 
 Man, however chaste in disposition, exquisitely sensitive, polished 
 in demeanour, beautiful of feature, delicate in perception of pro- 
 priety, graceful in motion, brilliant in imagination, rich in ac- 
 quirement, tasteful in accomplishments ; however finely modelled 
 and finished and mentally endowed, his ultimate shows him like 
 the product of the potter earthenware ! The porcelain may 
 be fractured and consigned to the sherd-heap, and in like manner 
 may be deposited its fabricator and animated participator of the 
 like earthy elements to the public cemetery or ceramicus. 
 
 " Whither the bodies of th' illustrious dead, 
 Are, by their friends, in solemn pomp convey 'd." 
 
 WARD. 
 
ORIGIN AND PROGRESS. 369 
 
 experiment, though almost by reasoning. All the 
 Arts of Life, all useful Manufactures, originate in 
 rude attempts to realise imperfect suggestions, or 
 render palpable " some model in the master's mind." 
 Invention is ever the daughter of necessity, and 
 equally as much in our day influences the progress 
 of Manufactures as in the earliest ages, when the 
 general manners were simple, arid the thoughts most 
 busy to accomplish whatever might conduce to social 
 comfort. Then, assuming that our colonised persons 
 have intellects clear and energetic, with minds 
 rational though uncultivated, the need to satisfy the 
 imperative calls of appetite by conveying food to the 
 mouth would quickly suggest the employment of 
 some utensil, either shell of fish, or rind of fruit, as 
 now practised in the country where the human family 
 was first located, and by the negroes of the colonies; 
 and the aborigines of transatlantic countries. The 
 preservation of articles of greater relish or refresh- 
 ment, when plentiful, would suggest vessels to con- 
 tain them ; and when the fermentative decomposition 
 had caused alcohol to evolve, the quantity formerly 
 taken would so affect the person's passions and rea- 
 soning powers, that in a state of ebriety men would 
 again, as formerly, commit actions, related by his- 
 torians, the subjects of regret during after-life 
 (Gen. ix. 21. ; xix. 31-38). The pliancy and adhe- 
 sive properties of Clay would readily suggest its 
 employment for various purposes. The great facility 
 with which Clay Wares can be made, the simple 
 principles of the first manipulations of the workman, 
 the importance of the articles, would induce different 
 persons to endeavour to understand them ; and, as in 
 
 2B 
 
370 CHEMISTRY OF POTTERY. 
 
 every other manual employment, the practice would 
 cause improvement and excellence. Utensils so 
 useful and readily fabricated would be subjects of 
 desire to the ingenious, prior to the construction of 
 the most rude dwelling ; and though uncouth, com- 
 pared with the productions of artisans bred up to the 
 Manufacture, and with shapes to accord with differ- 
 'ence of customs, and the usages of society, they yet 
 would have form, size and strength, adapting them 
 for their designed uses. Addition to the kinds, and 
 improvement in the quality of the Wares, would 
 ensue, because of the workman becoming more judi- 
 cious in selecting materials, more dexterous in using 
 his tools, and more intent on exerting his genius and 
 inventive faculties. Correction of the exuberances of 
 the design, and the ruggosities of the workmanship, 
 agreeably to the suggestions of new arrangements, 
 matured judgment, and refined taste, would promote 
 shades of elegance, as well as accessions to the 
 Manufacture. From such simple principles may 
 have originated this Art, which in our day is so 
 rapidly progressing towards perfection.* 
 
 * It is admitted that some tribes, descendants of the aboriginal 
 inhabitants of America, and others resident in the islands of the 
 Pacific Ocean, in skins and vegetable husks contain their oil and 
 other liquids intended for subsequent use ; and these are supposed 
 to have suggested the hollowing of blocks of wood, or of stone, in 
 which they immersed their food in water, and then caused the 
 whole to boil by adding incandescent stones. Yet these prepara- 
 tions and vessels presuppose a knowledge of some manual arts, 
 and possession of suitable tools. This filthy and inconvenient 
 practice they reluctantly and with apparent self-denial relinquish, 
 even after understanding that some earthy substances are refractory 
 
ORIGIN AND PROGRESS. 371 
 
 There is no especial interest in the speculation, 
 whether clay was appropriated first by the brick- 
 maker or the potter ; for even were this determined, 
 our knowledge would remain as at present in refer- 
 ence to the time, place, and persons ; yet both 
 applications early were important and their produc- 
 tions in demand. When comfort and convenience 
 rendered the erection of habitations indispensable, 
 in their construction during a long period the chief 
 materials were Bricks easily formed of clay, and 
 merely dried in the air. The employment of clay 
 for the purposes of the potter may have been sug- 
 gested by mere accident, as the retention of con- 
 densed dew or rain, by some impression of the foot 
 of an animal in the soft mass subsequently by the air 
 rendered hard and dry ; and its pliant and adhesive 
 properties would show with how little labour it might 
 be formed by the hand into different kinds of vessels. 
 Although known much longer than the bricks now 
 existing in Rome, and made more than 3000 years 
 ago, yet no such ancient specimens of earthenware 
 remain. Egyptian bricks and cinerary urns, even 
 though indisputably authenticated as of long prior 
 date, would fail to determine the question of previous 
 appropriation, or to support the proper claim to anti- 
 quity of invention. 
 
 The different portions of the human family, 
 wherever located, would experience like wants, and 
 
 in the flame ; also, that however useful fire may be in preparing 
 food, disadvantage would follow its application to the vessels of 
 wood and skins of animals, which by it would inevitably be 
 destroyed. 
 
 2B 2 
 
372 CHEMISTRY OF POTTERY. 
 
 originate similar Arts of Life ; and readily would 
 they embrace opportunities to gratify the one and 
 practise the other. And as those tribes of the family, 
 in different regions, who retain merely the civilisa- 
 tion of the first ages, possess some knowledge of this 
 Manufacture, I feel persuaded that its practice must 
 have prevailed previous to the migrations of the 
 post-diluvian tribes, and long anterior to the expecta- 
 tion of results so elegant and complicate as porcelain 
 and fiintware. The recent discoveries of travellers 
 in the transatlantic continent prove this, from a 
 period most remote, in portions of the globe, where 
 not even imagination had suggested that its produc- 
 tions were known. The American Archceologia sup- 
 plied numerous notices, a few of which I shall insert^ 
 prior to the continuous detail of well-determined 
 historical facts. 
 
 Being accustomed mentally to connect with the 
 idea of this Manufacture the associations of a series 
 of buildings for the different consecutive processes, 
 there might be some difficulty in obtaining for the 
 statements that ready credence, even by intelligent 
 and impartial readers, which they deserve, did we 
 riot suggest the great probability, that these potters, 
 and others of the very early practisers of the Art, 
 pursued their operations in a manner something 
 similar to that for the Manufacture of glass in the 
 present day adopted in Bohemia : The tribe of 
 artisans having found a suitable stratum of clay for 
 the bricks of the furnace, near a wood, commence 
 operations by cutting down timber in quantity suffi- 
 cient for erecting their habitations, sheds, workshops, 
 and warehouses ; next they quarry the clay, make 
 
ORIGIN AND PROGRESS. 373 
 
 the bricks, burn them thoroughly with the chips from 
 the timber, erect the furnace, and, for fuel, cut down 
 whatever quantity they need ; also burn brush-wood 
 to prepare the alkali for the Manufacture. Here the 
 artisans remain located, until in the processes all 
 the wood has been consumed. 
 
 The aboriginal inhabitants of Maypure, in South 
 America, and of Florida, are celebrated for their 
 Manufacture of a species of Delft ware, of excellent 
 quality, on which are ingeniously figured and cor- 
 rectly painted, birds, monkeys and crocodiles.* These 
 specimens of workmanship of ancient Indians, in 
 many properties equal, if they do not excel, those of 
 modern European fabrication. During the presi- 
 dency of Mr. Jefferson, persons employed in digging 
 at Palmyra, on the river Tennessee, discovered and 
 delivered to him various busts, of whose fabricators 
 no other traces remained, though conjectured to be 
 progenitors of the present race of Indians. The 
 figures are almost of the natural size, to below the 
 breast, and present good resemblances of the head, 
 face, neck and shoulders of persons unrecorded in 
 
 * " To form figures or impressions of particular subjects on 
 plastic clay would be early practised by the first potters, and is 
 the niost probable origin of all our boasted arts of sculpture, 
 painting, hieroglyphic design, writing, seal-engraving, and ulti- 
 mately of printing, and copper and steel-plate engraving. How 
 interesting is the series to the contemplative philosopher ! And 
 each Manufactory may have continued to imitate the approved 
 ornaments of its preceding owners, till we trace the patterns used 
 by the most early nations, when just emerging from their state 
 of hunting for daily food," SIR B. PHILLIPS (Walk to Kew, 
 p. 300). 
 
374 CHEMISTEY OF POTTERY. 
 
 tradition, but the well-executed features delineate 
 the physiognomy of the American copper-coloured 
 Indians. The countenance of one has most distinct 
 traits of the wrinkles of thought and age. But 
 whether objects of idolatrous worship, or mementos of 
 the country's most distinguished sons, remains to be 
 determined. I am not aware that any attempt was 
 made to ascertain whether their hard black substance, 
 analogous to Wedgwood's Egyptian, was a natural or 
 an artificial production, and consequently, they the 
 work of the sculptor, by the labours of the chisel, or 
 of the potter, first modelled and then baked. But 
 the latter is the more probable, and accords with the 
 object of mentioning their discovery. In Lord Hils- 
 borough's cabinet are two Indian vases, obviously very 
 antique, found on the shore of the Mosquito River ; 
 and, when mentioning the discovery of very ancient 
 potteries high up the Black River, Governor Pownall 
 thus describes these vases : " It is a decided fact, that 
 they are curious exemplers of some of the first efforts 
 of human ingenuity, and remains of what are be- 
 come antiquities even among the Indians." * Father 
 D'Acuina asserts, that by some of the Indian tribes 
 located on the shores of the river Amazon, in South 
 
 * Roylance Child, Esq., my neighbour, recently deposited in 
 the museum of E. Wood, Esq., Burslem, a beaker, or ewer, of this 
 Manufacture. The colour is brownish-red, the design beautiful, 
 the form that of a very tall turned cream-ewer of our artisans ; the 
 weight very light compared with porcelain, and a size or varnish 
 employed in place of a glaze. I examined it very attentively, and 
 the preservation of the fine lines, the absence of seams, its extreme 
 lightness, and the tout ensemble induce the opinion that it has 
 been cast with a clay which does not need a glaze. 
 
OKIGIN AND PEOGBESS. 375 
 
 America, this Manufacture has been pursued from an 
 era long anterior to any historical record, to all the 
 extent needful to supply the demands of neighbour- 
 ing nations, with whom they had established a regu- 
 lar traffic. The Indians of Louisiana at this day 
 fabricate very durable ware ; the clay or body is com- 
 pounded of what is commonly so named, with which 
 they mix certain proportions of calcined crystallised 
 felspar from granite ; and the vessels will bear any 
 temperature for culinary purposes, while the seggars 
 and crucibles will sustain the highest needful for 
 their furnaces and ovens. The vicinity of Salem, on 
 the Lake Erie, presents extensive remains of ancient 
 potteries. The opening of some burrows in Ross 
 County has supplied antiquarians with two covers 
 of vessels, fabricated of either marble, a calcareous 
 breccia, or terra cotta, which for all valuable proper- 
 ties and excellence will bear comparison with any 
 by Italian artists now produced of similar materials. 
 Several earthen vessels were obtained, which ade- 
 quate judges regard as equal in quality and work- 
 manship to any present productions of the art. At 
 Marietta, in 1819, were found specimens of ancient 
 earthenware, which in excellence and the exhibition 
 of attention to neat workmanship, are not inferior to 
 any productions of the present race of Manufacturers. 
 They seem to be compounds of clay and pulverised 
 flints ; and they still remain completely firm and 
 solid, though long exposed to all the alternations 
 of the atmosphere, prior to being preserved in a 
 museum. Others are less compact, dense and firm ; 
 and only partially, if at all, baked ; and they seem 
 compounds (like the ware fabricated by the Indians) 
 
376 CHEMISTRY OF POTTERY. 
 
 of clay and pulverised clam shells. All the speci- 
 mens to which these remarks refer, display those 
 proofs of persevering industry and genius during the 
 progress of the Art, with manipulations simple and 
 common, of which only inadequate ideas will be 
 formed by persons ignorant of the processes. 
 
 The authority of sacred history supports the 
 assertion that B.C. 2200 years, and 500 years prior 
 to the migration and settlement of Jacob's family in 
 its territories, the kingdom of Egypt was in great 
 prosperity ; and its people, blending fact with fable, 
 as previously mentioned (p. 368), claim a very early 
 practice, and also perfection in the processes of this 
 Manufacture and that of glass. Siracides remarks 
 that covering earthen vessels with a crust of glass 
 is an ancient practice, which has recently been fully 
 corroborated by the indefatigable Belzoni ; who says, 
 "the art of varnishing and baking the varnish on 
 clay was in such perfection, that I doubt if it could 
 be imitated at present." Researches, p. 173. The 
 quantity of vessels by this people required is not of 
 importance ; but it would extend with the demands 
 of the population to contain supplies of oil, juices of 
 fruits, water, etc., and the ease and readiness with 
 which could be acquired by the workman proficiency 
 in its processes, and dexterity in its manipulations.* 
 
 * Herodotus could not possibly be ignorant that Egypt and 
 Phoenicia were old nations compared with the Grecian states, 
 which received their arcanum alphabeta from a Phoenician, and 
 whose sages visited Egypt to acquire correct acquaintance with 
 the knowledge current in their day. He incidentally notices the 
 .scarcity of earthen vessels among the Greeks, and yet seeks to 
 
ORIGIN AND PROGRESS. 377 
 
 In building the Tower of Babel (Gen. xi. 3), 
 there were used bricks " burned thoroughly ; " and 
 
 flatter their vanity, and indulge their prejudices, to augment their 
 celebrity, by making them potters for all Egypt and its dependen- 
 cies, " Twice in. every year there are exported from different 
 parts of Greece to Egypt, and from Phoenicia in particular, wine, 
 secured in earthen jars, not one of which jars is afterwards to 
 be seen, for the principal magistrate of every town is obliged to 
 collect all that are imported to the place where he resides, and 
 forward them to Memphis. The Memphians fill them with water, 
 and afterwards transport them to the Syrian deserts. Thus all the 
 earthen vessels carried into Egypt, and there carefully collected, 
 are continually added to those already in Syria." Book in., 
 Sect. 6th. The natives of the interior of Africa accomplish their 
 passage across small streams by securing each end of a stout 
 pole to a large gourd ; and seated across the floating pole, with a 
 second pole the passenger forces himself across. In some parts of 
 the East the ferry-raft, or Charpoy, is formed of stout frame- 
 work of bamboos, not unlike a set of bedsteads, and secured 
 together by net-work of cords which support the cargo. Beneath 
 the posts and rails are inverted and well-fastened beaker-jars 
 named Kogerii, in which is compressed such a quantity of air as 
 renders buoyant the whole, which is readily pushed through the 
 water by the ferryman. A practice somewhat similar seems to 
 have obtained among the Egyptians in the days of Juvenal, whose 
 surprise seems excited by the singularity of the danger from 
 obstacles which might be encountered, in fine weather, and the 
 vessels being dashed against each other by the gale. These rafts 
 .he names earthen-boats. Sat. xv. 126-128. 
 
 " Haec saevit rabie imbelle et inutile vulgus, 
 Parvula fictilibus solitum dare vela phaselis, 
 Et brevibus pictae remis incuinbere testae." 
 
 The earthen-boat, alone, through dangerous tides, 
 With wild and vulgar ruthlessness he guides ; 
 Or else reclining on his painted shell, 
 Its short length paddles through the briny swell. 
 
378 CHEMISTEY OF POTTEKY. 
 
 we may suppose their use well known in Egypt from 
 the great quantities required (the remaining speci- 
 mens of which excite our surprise because of their 
 durability) before the ingress of the Hebrews (B.C. 
 1706, Gen. xlvii. 11), and the rigour with which, 
 from this people, the taskmasters exacted the tale 
 until the Exodus. Will it be too great an assumption 
 
 Dr. Harmer (vol. i., p. 90) mentions that Upper Egypt 
 supplied the Delta, or Lower Egypt, with sufficient for all pur- 
 poses of home consumption and exportation. The potters were 
 aware that the porosity of the vessels in biscuit state, permeated 
 by water till almost filled, might cause the raft to swamp ; there- 
 fore they covered each with varnish (by us called glaze), and 
 connecting them as a raft or float, sent them down the Nile to 
 Memphis. The great frequency of the practice proves that not 
 a small number of jars would be required, and diminishes the 
 probability of Greece affording the supply, as Herodotus insinuates- 
 Indeed, I think the country where the practice obtains must have 
 known little of Greece or her customs, else these last would have 
 suggested the use of boats of more buoyant and less fragile ma- 
 terials. " It may be proper to observe (says Harmer) that these 
 floats are not constructed to pass up and down the Nile like boats, 
 or designed to carry goods upon them, though they may occa- 
 sionally be put to that use [as during the time of roses blowing, 
 for making rose-water, in profusion cultivated at Fiume, bee- 
 hives are brought on such rafts, and when the flowers are decayed, 
 the hives are returned to their owners] ; it is only an easy way 
 which the Fellahs discovered, and by their descendants observed,, 
 of conveying their earthenware from Upper Egypt, where it is 
 made, to the Delta, or lower part of the country, where, on its, 
 arrival, the float is taken to pieces, and the vessels are sold to the 
 inhabitants." Norden, the doctor's authority, also states (Travels,. 
 vol. ii., p. 75) : " To cross the Nile, the inhabitants of Upper 
 Egypt contrive a float made of large earthen pitchers [jugs] tied 
 closely together, and covered with leaves of palm-trees ; and the 
 man who conducts it has commonly in his mouth a cord, with, 
 which he fishes as he sails along." 
 
ORIGIN AND PROGRESS. 379 
 
 that the fabrication of bricks would introduce also 
 that of vessels ? In Egypt this people learned many 
 Arts, which they practised after their emancipation. 
 The products of this art are often mentioned by 
 Moses (Lev. vi. 28, Num. v. 17), and while they 
 imply that he was acquainted with their usual mode 
 of Manufacture, I think we should ill compliment 
 that numerous and intelligent people, by the supposi- 
 tion that this knowledge was exclusively possessed 
 by their leader. Neither ought we to conclude on 
 the non-existence of potters among them because 
 they are not specially mentioned. That wares formed 
 of clay, whether we call them pottery, porcelain, 
 or earthenware, were in request, and of excellent 
 quality, prior to any historical mention of their use, 
 is clearly proved by the beautiful specimens which 
 are usually discovered deposited with the mummies, 
 and coeval with their existence. These with beads 
 have been found, and even vessels, covered with a 
 rich glaze of a blue colour ; and pieces of blue 
 enamel, much similar, have been found in the tombs 
 at Thebes. Mr. Delaval applied tests to a portion 
 detached from a small image found with a mummy 
 to ascertain the colouring materials, and was of 
 opinion, that upwards of 2000 years anterior to the 
 employment of chemical investigation to such subject, 
 there existed accurate knowledge of the virtue of 
 oxide of cobalt to give a beautiful blue tint to any 
 vitrified chemical compound of silica, alumine, and 
 alkali, though this was applied for this purpose 
 only since the early part of the eighteenth century, 
 A.D. That iron was therein employed recent facts 
 fully prove. As specimens show their having been 
 
380 CHEMISTRY OF POTTERY. 
 
 thrown on the "potter's wheel" it must have been 
 used in Egypt for the purpose. The most authentic 
 records mention it ; Homer, as well as Moses, regards 
 it as very ancient in his day.* 
 
 The Canaanites of holy writ among their 
 branches had the most distinguished merchants 
 and most celebrated philanthropists of that era, the 
 Phoenicians. In their commercial migrations they 
 either supplied colonies, already established, with 
 the Manufactures then current, in the way of barter, 
 or placed their countrymen, with adequate know- 
 ledge to pursue whatever branch might seem best 
 adapted to the locality. They are admitted to have 
 been well skilled in the processes requisite for manu- 
 facturing excellent earthen and glass vessels. Of 
 the site of their own potteries history fails to inform 
 us ; yet although the two cities Tyre and Sidon 
 were the marts most noted, of their being the seat 
 of the Manufacture there is not the least proof; 
 but from them, more than 1200 years before the 
 
 * The " magic of a name " is here obvious. The invention of 
 the potter's wheel Strabo assigns to Anacharsis, the Scythian (or 
 Gothic) philosopher, and is followed by Seneca, Suidas, Diogenes, 
 Laertius, and others, whom it were insult to suppose ignorant of 
 the wares supplied by Tyre and Sidon, marts when Athens was 
 mere hovels. Pliny (lib. xxxv., sec. 14), on the authority of 
 Diodorus the Sicilian (iv., 319), asserts that the alleged inventor 
 brought it from Scythia. This personage was otherwise named 
 Icarus, the nephew or grandson of Daedalus, the architect, in the 
 days of Solomon ; and probably, after completing his travels in 
 search of information, he might benefit the Greeks by communi- 
 cating the model of the machine. The date of the assigned inven- 
 tion is more than 1000 years later than its known use, consequently 
 will not support the allegation. 
 
ORIGIN AND PROGRESS. 381 
 
 advent of the Messiah, most ports of the then known 
 world obtained supplies. No doubt can arise that 
 they would select the situation most suitable ; and as 
 the vale of Chozeba in subsequent times (the valley 
 of the Son of Hinnom, very probably a noted potter, 
 and maker of the earthen-gods which so abounded 
 through the idolatrous portion of Jacob's family, 
 1 Chron. iv. 22, 23, was the site of the Jews' potteries, 
 and is remarkably placed for connection with Tyre, 
 Sidon, Joppa, and Jabneel, I suggest the probability, 
 that there the Phoenician potters were employed, and 
 that the Manufacture was continued for the special 
 advantage of the Jewish kings after the conquest. 
 
 The Phoenicians also excelled in the fabrication 
 of figures of remarkable persons and objects, so much 
 demanded to ornament their groves for licentious 
 rites and ceremonies, and which so greatly promoted 
 idolatry, that divine displeasure annihilated many of 
 its votaries.* 
 
 * Pliny quotes Praxiteles for the authority, " that figulus 
 primus inveniit ex argilla finger e similitudines ; " and in the 
 art of modelling clay the progress was more rapid, and the im- 
 provement greater, than in any other, because of the facility with 
 which it was accomplished. The historian (lib. xxxv., c. 12), not 
 aware that there existed specimens of earthenware figures, now 
 acknowledged to have been employed in decorating Egyptian 
 mummies many centuries prior to the date of the introduction 
 of potting into the State of Corinth, gives the following pleasing 
 anecdote to prove the origin of sculpture in the strongest emotions, 
 of the mind, and also to establish the claims of the Greeks to the 
 merit of the invention ; not that I wish to question the accuracy 
 of the statement as connected with the parties mentioned, only 
 that, previously, others had practised the art : "A celebrated 
 potter of Sicyon had a beautiful daughter, named DIBUTADES,, 
 
382 CHEMISTRY OF POTTERY. 
 
 The Phoenicians, according to Strabo (I. 3), at a very 
 early period visited Britain for tin, not then known to 
 exist in any other country, and during many ages supplied 
 its inhabitants with vessels of earthenware and glass. There 
 are in holy writ references to our country as one of "the 
 
 who, with her father's approbation, had encouraged the attentions 
 of a sailor, occasionally absent for some time. On returning 
 after a rather protracted absence, he was indulged with the favour 
 of a private interview, during the hours when her father was 
 at rest, ignorant of the assignation. The lover had been much 
 fatigued at his return, and the detail of incidents to his beloved 
 prolonged the interview until sleep overpowered his senses as 
 they sat by the midnight lamp. The reflection of his features by 
 the rays of light strongly marked the profile on the wall, and the 
 watchful fair one thus had her attention directed to the means of 
 securing the likeness of her lover as an object of regard during 
 his absence. With the end of a half-burnt stick as a stile, she 
 quickly traced the outline, no doubt so truly in accordance to 
 Nature that memory would readily supply all the features omitted. 
 The father afterwards noticed this sketch ; he applied clay to the 
 outline, filled up whatever was requisite, and in a short time pro- 
 duced a correct likeness of the face for his daughter's constant 
 notice when the idea of her lover presented itself. How must 
 this modeller have been gratified while proceeding : the mere 
 lump of clay assumes a reality of figure, to which each point of 
 view suggests additional modification by the tool ; to the daughter 
 all is real, tangible, and needs only vitality, which the imagination 
 is ready to supply, as she gazes on the lips inviting her salute ; 
 and witnesses how, agreeably to the simplicity of truth, sym- 
 metry secures 'the just proportions of form and size, and the 
 perfect lines of ideal beauty. And at a period not later than 
 the eighth century before Christ this clay figure suggested the 
 kindred practice of casting, and the now more esteemed art of 
 sculpture. This production, regarded as the first essay of the art 
 in Corinth, was long preserved in the public repository, but was 
 destroyed by the foolish and barbarous Mummius Achaius, when 
 he sacked the city. Those which Solomon established in the 
 vicinity of his capital to indulge his wives and concubines 
 (1 Kings xi. 3, 7, 8), and in imitation of which other kings also 
 
ORIGIN AND PROGRESS. 383 
 
 Isles of the Gentiles," arid tp the metal tin, Gen. x. 5, 
 Num. xxxi. 22, 1 Kings x. 22, Ezek. xvii. 4, of the respective 
 dates 2200, 1460, 1000, and 600 years B.C. The mention 
 of the metal in the Iliad proves its use prior to Homer's 
 day. Many writers mention the statement, that from Tyre 
 and Sidon the Phoenician sailors, in their trading vessels, 
 visited, for its tin, the land of On, Britain, at least 285 years 
 before the birth of Moses. (See Cellarius, p. 15 ; Cesar, 186, 
 
 established (xiv. 23, xvii. 28-33), probably suggested the cerami- 
 cus at Athens ; the shining whiteness of the figures suggesting the 
 application of the word to wax-work, and giving the name to the 
 spot where figures of the "illustrious dead" were placed over 
 their graves.* The kings of Judah, from base motives, either 
 encouraged or winked at the proneness to idolatry which 
 supplied funds for their luxury ; and as statuary marble was 
 introduced only in the eighth century before the Christian era, 
 and numerous statues had been erected in different groves, etc., 
 long previously ; and, when certain monarchs had cut down 
 these, others who succeeded had fresh images supplied, set up; 
 may not the expression, " to pass through the fire," regard as much 
 the potter's process of baking figures of the objects of idolatrous 
 worship, as of sacrifice of the person mentioned. (See Wisdom 
 of Solomon, xv. 1, 13, 15.) The "Potter's-field" was a public 
 cemetery, and we have no proofs of its being the ground where 
 they wrought tygs (vessels for drink), as the Saxon "cecer 
 tig el wyrhtena" implies. 
 
 * In the Ashmolean Museum, Oxford, is preserved an excellent specimen of 
 ancient pottery, on which, in its natural size, is the face of a beautiful woman, 
 whose physiognomy completely differs from that of the Greeks. It is fully 
 described, page 1017, vol. xv. , Phil. Transactions. Of the productions of these 
 early Phoenician potters, most excellent specimens from excavations under the 
 city of Acre, in great numbers, of vases and other vessels, are now preserved 
 in the museum of the Baron Judica, at Calazolo, all of which are long 
 anterior to the Christian era. And of the value attached to some of these 
 specimens an idea may be conceived, when I state, that in the Scudi Palace, 
 Naples, are numerous specimens ; and among the cinerary urns is one for 
 which the king of Naples paid 10,000 piastres, or 2,200 sterling. 
 
384 CHEMISTKY OF POTTEEY. 
 
 204 ; Arist. De Mundo, iii. 614.) Wherever this people- 
 introduced articles of commerce, they ultimately established 
 Manufactories ; and in the Philosophical Transactions (xix. 
 319, xxii. 564) are mentioned vestiges and even sites of 
 extensive potteries in different counties, where scarcely 
 imagined probable ; and which plainly indicate, that in 
 those places operations had ceased long anterior to any 
 authentic records. Because of either some peculiar senti- 
 ment of respect, or regard to the long-cherished doctrine 
 of the body's resurrection or its bastard offspring, trans- 
 migration of the soul -with the corpses of important per- 
 sonages were deposited in sepulture vessels containing 
 spices. And which custom is the cause of the numerous 
 specimens of earthen urns, beakers, and bowls, which at 
 different periods have been obtained when opening barrows 
 in several parts of the kingdom, rude in formation and 
 deficient in taste in regard to ornament, but not the less 
 interesting from those qualities. They are regarded as 
 objects of peculiar importance, because, having been found 
 in situations which they must have occupied many centuries 
 prior to the Roman invasion, they establish the fact of the 
 ware being used for different purposes. And because their 
 origin is incontestibly not Roman, the difficulty is attempted 
 to be superseded by making them Venetian, though 
 Venice, even if it were anterior to Rome, was not then 
 known to have potteries ; and there is much probability that 
 by mistake the name has been substituted for Phoenician,. 
 which people had ceased, soon after the time of Solomon, 
 to be the general merchants of the then known world, and 
 could not have supplied all parts of Britain, except at very 
 great risk of loss and damage.* 
 
 *In the Archceologia (282, etc.) is reference to others obtained from a 
 British pottery, long submerged beneath the tides of the sea. In the cottages 
 of the fishermen near Margate Roads are frequently to be seen earthen 
 vessels, of rude workmanship, and coarse materials, which have been ob- 
 tained from the nets at various times thrown on a shoal (because of these 
 vessels called the Pudding Pan Sand), about two leagues from the shore ia 
 
ORIGIN AND PROGRESS. 385 
 
 The Phoenicians, unable or unwilling longer to endure 
 the intolerable exactions of Solomon, whom they had 
 benefited in numerous ways (1 Kings ix. 21), and there 
 being great probability of additional bond-service (B.C. 
 1000), a colony of potters and other artisans emigrated 
 from Tyre, across the Mediterranean Sea, to the foot of 
 Mount Vesuvius, and at Nola commenced their Manufac- 
 ture of earthen vessels, and continued it, with a dexterity 
 of workmanship, and with such taste in shapes and orna- 
 ments, and a high state of excellence, elegance and per- 
 fection, as have scarcely yet been equalled ; and obtained 
 from the rulers of the country, and subsequently from the 
 Roman government, in behalf of the artisans, every possi- 
 ble encouragement. Pliny, where already quoted, mentions 
 that Numa formed into a seventh confraternity the potters, 
 who at a later period assumed the name of Etruscans. 
 But although it does not appear clear whether this was 
 applied to them for distinction from others, who had sepa- 
 rated and commenced the Manufacture in other places, 
 
 that part of the Margateploads called the Queen's Channel, near the mouth of 
 the Thames. Upon the greater number of these vessels, adapted for the rites 
 of sepultiire and other religious ceremonies, is very neatly impressed the name 
 ATTILIANUS, and also upon fragments, finer in quality, but less durable, and 
 very rarely regarded as worth preserving, because of no use. The opinion 
 prevailed that here had been sunk during the time of the Roman domination 
 a trading vessel, whose freight of earthen vessels was now being obtained from 
 the deep, in which they had so long time been immersed ; perhaps because the 
 currents had carried away the timbers of the vessel. But this opinion was 
 proved illusory by some nets bringing up bricks of Roman fabric, well 
 cemented together. In 1778 more research ensued ; Ptolemy's Geography 
 was examined, and in his second book, reference is made to a small island at 
 the mouth of the Thames, as existing two hundred years anterior to the visit 
 of the Romans to Britain, and in that particular part where now is the shoal, 
 but which island is not mentioned by Caesar, and is, therefore, supposed to 
 have been submerged prior to his ambitious invasion of this country. The 
 conclusion drawn by Governor Pownall, is, that upon this island was once a 
 pottery, and that it was either owned (most probably) or managed by the 
 person whose name is thus singularly preserved to our day. This mode of 
 fixing the name suggested the practice to WEDGWOOD, and is continued by 
 his descendants, and adopted by many others in the present day. 
 
 2 c 
 
"386 CHEMISTRY OF POTTERY. 
 
 especially at Arezzo and Faenza (whence probably fayance, 
 the French name for earthenware), it is not to be contro- 
 verted that from here went the potters to Corinth, which 
 city afterwards became celebrated for the excellence of the 
 ware made by the potter Demaratus, B.C. 600, and who 
 afterwards left his Grecian connections for the more 
 celebrated and convenient potteries of Italy. 
 
 Very early were the Persians celebrated for the Manu- 
 facture of porcelain, if we credit Propertius, who wrote in 
 the time of the Emperor Augustus, and as quoted by Sir 
 John Chardin. Dr. Harmer boldly asserts (Vol. I., 74, 5), 
 that the best Asiatic porcelain is that of Persia ; and he 
 mentions principally Shiraz, the capital of Persia Proper; 
 also Metched, in Bactriana, and Yesd, Kirman, and especi- 
 ally Zoreridi, in Caramania. There is also a tradition, that 
 on one occasion the potters at Yesd sent to Ispahan, in 
 defiance of those in that city, a porcelain vessel, of twelve 
 pints content, yet its weight only the eighth part of an 
 ounce (probably pound ; for a sheet of paper of the like 
 size would weigh a drachm).* 
 
 * The following anecdote will prove that the Persians are aware of the 
 excellence of their productions, and how easily, for their home supplies, the 
 Dutch may mix it with the porcelain of Nankin: In 1666 the Dutch am- 
 bassador to the court of Persia was exhibiting the many rich presents he had 
 brought for the reigning prince, among which were fifty-six pieces of very 
 valuable Chinese porcelain. These the prince viewed with contempt, in de- 
 rision inquired what they were ? and on being informed, laughed most heartily 
 at their non-importance, to the very great confusion and mortification of the 
 ambassador. Unacquaintance with these facts is the probable cause why 
 Robertson, with a good intention, no doubt, supports the attempts of the Abbe 
 le Bland and M. Larcher (Mem. de Litterat. XLIIL), to prove that the very 
 valuable vessels mentioned by Pliny (xxxvii. 2), as brought from Pontus, B.C. 
 64, by the victorious army, and first seen at Rome at Pompey's triumph, and 
 called vasa murrhina, murrina, and murrea, were formed out of a transparent 
 stone, dug from the earth in some of the eastern provinces of Asia, arid by 
 some persons called Parthian agates, whitish, but variolated. These writers 
 do not assign any probable cause for the number found together being of the 
 same kind and quality ; neither do they state where similar stones are now to 
 be found, nor supply any slight traces of the practice of fabrication; and yet 
 
ORIGIN AND PROGRESS. 387 
 
 The opinion entertained by persons (whose education 
 has led them to suppose that the Romans taught the 
 Britons all the Arts of Life) of this Manufacture having origi- 
 nated with the conquest of this nation by that unprincipled 
 and ambitious people, I feel bound to show devoid of 
 solid foundation. I will admit that in the vicinity of some 
 of their military stations have been discovered remains of 
 small potteries; and that bricks, 17 by 11 inches on the 
 surface, and 2J in thickness, remain in the walls of Veru- 
 lam, a little south of St. Albans. Also, that in Hyde Park 
 were dug up, in the beginning of the eighteenth century, 
 water-pipes, 2 inches thick, and with their joints formed 
 of common lime-mortar moistened with a vegetable oil, and 
 assigned to the Romans, because Vitruvius mentions water- 
 pipes fabricated of potter's clay. But, as amulets (glain 
 neidyr) about half as wide as the finger ring, but much 
 thicker of glass, usually of a green colour, but others blue, 
 and wavy of red, blue, and white, used as a charm for the 
 vulgar, are yet preserved entire, which were manufactured 
 by the British Druids many centuries anterior to the 
 Roman conquest, before I concede every relic of ingen- 
 uity to that people, some indisputable authority must 
 convince me that among the Britons had ceased to exist 
 
 we cannot suppose that there would be entire loss of a Manufacture (which 
 for excellence of workmanship required and manifested considerable judgment 
 and dexterity) in the country where such valuable stones were quarried. 
 Had these writers just attended to the geography of the country, they would 
 have seen the great probability, not merely that the vessels were of eastern 
 Manufacture (as they seem to admit), but that they were indeed Persian 
 porcelain vessels, and in quality similar to those used in the time of those 
 great scholars, Cardan and Scaliger, both of whom entertain this opinion, 
 though seldom on any other agreeing. There is close approximation to the 
 facts also in their speculations, from the statements of travellers, on the 
 component materials of the vessels: "they were formed of eggs and sea- 
 shells, marine mollusca, beaten small, and buried from eighty, to one hundred 
 years ; " as the fluid mass of the preparing clay is not unlike beaten eggs, and 
 the long deposit of the mass underground is even in our day a practice in 
 China. 
 
 2 c 2 
 
388 CHEMISTRY OF POTTERY. 
 
 all that native genius which had in prior ages enabled 
 them to confer inestimable obligations on Greece as 
 well as Rome ; for we have these authorities Gobryas,. 
 the Persian, Hellanicus, a writer long prior to Hero- 
 dotus, Socrates, Plato, and Diodorus Siculus, that our 
 ancestors sent, in Phoenician trading- vessels, to Delos, three 
 virgins, with tables of our copper and tin, or copper 
 and zinc, on which were written the doctrines of religion, 
 especially concerning a future state of retribution, the 
 blessedness of the just, and the misery of the wicked. 
 Also, that the colonisers of Britain, long before Rome was 
 even a range of sheds, or dignified with a name, were not 
 incited by the utility of domestic utensils, the plentiful 
 supply of materials, and the facility with which they could 
 be fabricated, to render themselves expert in providing 
 substitutes for those destroyed by accident or using. Also,, 
 that Verulam was of Roman erection, and chiefly occupied 
 by that people's legions. Also, that such water-pipes are 
 not of Staffordshire Manufacture, where from periods long 
 prior to any historical records, clay for the purpose has 
 been quarried to an extent, proved by existing excavations, 
 after long being receptacles of potsherds, etc., only to be 
 credited by persons who inspect them. Besides, the 
 opinion presupposes, that among the legions were persons, 
 who greatly excelled, and had plenty of time which they 
 could and did employ in the Manufacture ; also, that much 
 earthenware was used by the armies ; and further, that only 
 the most rude specimens are preserved to posterity. With 
 about equal propriety might I assert that Knut, the Dane, 
 established the Manufacture in Staffordshire, now so flour- 
 ishing, as the staple of the borough of Stoke-upon-Trent. 
 For there is an equally indisputable fact, that at one of his 
 military posts, (ffcTStfrtOH OH ft C I (Till) Chesterton-on- 
 the-Loam, one extremity of Knutton-heath, and only two 
 miles distant from Knut-Castle-on-the-Loam through the 
 errors of copyists corrupted in modern orthography to 
 Newcastle-under-Lyme), at the depth of 7 to 10 feet below 
 
ORIGIN AND PROGRESS. 389 
 
 the surface, the late Mr. Josiah Wedgwood and some 
 friends discovered appearances of an early pottery, such 
 as we might imagine would be presented by the borough 
 of Stoke-upon-Trent, was it to be submerged, and at the 
 expiration of many centuries were to be again exposed, the 
 foundations and remains of workshops, ovens, masses of 
 potsherds, and other refuse from the vessels injured by 
 baking. 
 
 In the chapter already quoted, Pliny mentions the 
 usefulness of clay, "in yielding us the conduit-pipes for 
 water, also tiles, flat or hooked, or made with crotchets at 
 one end, to hang upon the sides of the roof, or chamfered, 
 to form gutters for the flow of water, or curbed for creases 
 to clasp both sides of the ridge, besides the vessels which 
 are turned with the wheel, and worked round ; yea and 
 large earthen tuns and pipes, constructed to contain either 
 wine or water." Also, " Vitellius, while he was emperor, 
 caused a charger to be made and finished, which cost a 
 million of sesterces [if so, 8,000 sterling: but possibly an 
 error of the copyist for a less sum], for the baking of which 
 a furnace was purposely erected." * There is additional 
 
 * In accordance with this mode of erecting a furnace expressly for a parti- 
 cular object, I find the following statement by Plutarch, in his life of Pub- 
 licola : " Tarquin, while yet upon the throne, had almost finished the temple 
 of Jupiter Capitolinus, when, either by the direction of an oracle, or upon some 
 fancy of his own, he ordered the artisans of Veil to make an EARTHEN CHARIOT,* 
 which was to be placed on the top of it. Soon after this he forfeited the crown. 
 The Tuscans, however, modelled the chariot, and set it in the furnace ; but the 
 case was different with it from that of other clay in the fire, which con- 
 denses and contracts on the exhalation of the moisture, whereas it enlarged 
 itself, and swelled till it grew to such a size and hardness that it was with dif- 
 ficulty they got it out even after the furnace was dismantled. The soothsayers 
 being of opinion that this chariot betokened power and success to the people 
 with whom it should remain, the people of Veii determined not to give it up to 
 the Romans, but upon their demanding it, returned this answer : ' That it 
 
 * A remarkable corroboration of the opinion I have given, p. 381, of the employment 
 of the Potter's Art for objects scarcely accomplishable by the labours of the sculptor. 
 
390 CHEMISTRY OF POTTERY. 
 
 support to Pliny's statement in the translation by Wickes 
 Skurray of the Marquess Don Marcello di Vinuti's Ac- 
 count of the Discoveries at Heraclea, in Pontus, published 
 in 1750. He says (p. 110): "Through a door of white 
 
 belonged to Tarquin, not to those who had driven him from his kingdom.' 
 It happened that a few days after there was a chariot race at Veii, which was 
 observed as usual, except that as the charioteer who had won the prize and 
 received the crown was gently driving out of the ring, the horses took fright 
 without any visible cause, but either by some direction of the gods, or turn of 
 fortune, ran away with their driver at full speed towards Rome. It was in 
 vain that he pulled the reins, or soothed them with words ; he was obliged to 
 give way to their career, and was whirled along till they came to the capitol, 
 where they flung him at_ the gate called Ratumena. The Veientes, surprised 
 and terrified at this incident, ordered the artist to deliver up the chaiiot". 
 Allowing that the expense was borne by funds supplied by the emperor, I 
 cannot but suppose their processes, as well as materials, must have differed 
 greatly from those of other potters of the Roman era, as well as from those of 
 our own artisans of the present day, dependant on their own industry, genius 
 and capital. In the Archceologia are Remarks on Roman Antiquities of the 
 Durobrivse of Antoninus, with correct figures of the subjects now to be men- 
 tioned : At Castor, Northamptonshire, Mr. E. T. Artis discovered, in a state 
 of complete preservation, the BISCUIT and GLOSS OVENS, which were portions 
 of a Roman pottery, with vessels therein, as they were placed for baking, and 
 remained while and after the town was destroyed by conflagration. Both ovens 
 will not compare with those in present use in magnitude. The Biscuit-oven 
 can scarcely be called conical ; the diameter at the bottom is 4 feet 6 inches, 
 and at the top 5 feet, and its height is 4 feet. From the hearth, at 18 inches, is 
 a floor of triangular tiles, 3 inches thick, with their points resting on a pillar in 
 the centre of the fire-chamber (or receptacle of the fuel, supplied through an 
 aperture in the front) ; the broader end of the tile is perforated with two cir- 
 cular holes, an inch in diameter, through which passed the flame to bake the 
 vessels in the upper chamber, or oven, 2 feet 3 inches deep. As only red pottery 
 was found in the oven, and no trace of seggars (certainly not required for such 
 ware), we have no proofs for or against their use. Also, whether the sides were 
 higher or not* .is not determined, nor the manner in which it was covered; 
 but probably a conical arrangement of flat tiles was employed for this purpose. 
 The Gloss-oven is formed of two hemispherical muffles or seggars, 2 feet 
 6 inches diameter, together ranged behind the biscuit-oven, and by a large rim 
 or flanch suspended over the fire-chamber, similarly supplied with fuel through 
 an aperture in the front, and beyond the hindmost seggar was another aperture 
 for the smoke to escape. On each seggar fits another, almost hemispherical 
 and rather longer. Both were half filled with wares in the last stage of their 
 Manufacture. Professor Haussmau has proved that the ancient vases were 
 
OKIGIN AND PROGBESS. 391 
 
 marble we entered a room, 14 yards long, and 8 broad, 
 and which led to another room of the same length, but 
 almost square. Round the inside of both these rooms, 
 close to the wall, and about half a yard high, ran along a 
 kind of bench, . covered with a marble pavement, which at 
 first seemed to have been used for a seat, but on coming 
 nearer to more closely examine it, I perceived some of the 
 pieces of marble were round, like stopples ; and on their 
 removal, I found they were the covers of some very large 
 earthen jars, fixed in with mortar, with their necks inclosed 
 just level with the seeming bench. These vessels were of 
 a round form, and would each contain ten barrels, Tuscan 
 measure. On one of these vessels is- this inscription 
 OPUS, DOLIARE, VINARIUM. The names on the handles 
 and necks of these vessels are those of the makers. The 
 names written with ink were those of the owners of the 
 liquor contained therein. The multiplicity of names caused 
 the conjecture that these apartments had been for the 
 soldiers who were stationed to guard the walls, and that 
 whatever name was written on the vessel, to that person 
 belonged the wine contained therein, whether by purchase 
 or by allowance." 
 
 The preceding details having reference to dates in- 
 disputably prior to any accredited record with which 
 Europeans are acquainted of the Manufacture by Chinese 
 artisans, do not insinuate priority of operations, yet clearly 
 elucidate what must at any given era have been contempo- 
 raneous with them. There necessarily is some obscurity 
 attached to the whole; and, with all inquisitive minds, this 
 I regret, for the industry of research is checked, and the 
 ardour of ambition damped by the fact that the most useful 
 and necessary inventions have not perpetuated any trace 
 
 soaked in varnish and then baked. And it is evident that these seggars could 
 not have fixed that portion of heat which would vitrify a glaze, however 
 fusible, as the heat communicated would be only little more than that Afforded 
 by the sand-bath in chemical processes. 
 
392 CHEMISTRY OF POTTERY. 
 
 other than themselves of their inventors, as the most 
 superb and durable, like the less elegant and perishable 
 monuments, have failed to commemorate their subjects and 
 founders. 
 
 The earliest written historical records of the Art among 
 the Chinese the annals of the occurrences, transactions, 
 and subjects worthy of being most particularly remembered, 
 of the city Fou-leang, in the province of Kian-gsi, the dis- 
 trict in which is situated King-te-ching, the locale of the 
 China Manufacture mention the productions, as being so 
 excellent, A.D. 442, as to be an object of interest to the 
 imperial court. Such was then its high state of proficiency 
 and perfection, that to these potteries were deputed two 
 mandarins to superintend the workmen while employed in 
 the Manufacture of porcelain for the use of the emperor's 
 household a most unpleasant affair for the Manufacturers, 
 and the probable cause why no attempts have succeeded to 
 transfer the Art to the capital, Pekin ; but, by all who have 
 had opportunity for observation, admitted to be a part of 
 the policy of the government thus obtrusively to interfere 
 with the private affairs of its subjects. 
 
 These records, however, are completely silent alike 
 concerning the era of the invention, the name of the 
 inventor, the date of its attaining its acme of perfection, 
 and the master-minds who so successfully improved the 
 processes and manipulations, as to enable the artisans to 
 surpass in excellence of productions those of all other 
 contemporary nations with whom they were acquainted. 
 That the whole series of operations continue unaltered, 
 will not be any cause of surprise to persons who have been 
 informed of the conceitedness of the Chinese in general ; 
 and who for a moment reflect, that whenever any attempt 
 is made to introduce improvements into any of the Arts of 
 Life, those who have been employed therein present the 
 chief difficulty, because of the fondness entertained for 
 old practices, in which they, perhaps, are expert, and from 
 regarding each improvement as an idle and useless 
 
ORIGIN AND PROGRESS. 393 
 
 innovation on the long-established procedure of their 
 ancestors. 
 
 Earthen vessels of truly excellent quality, however, as 
 well as the finest specimens of porcelain, * are yet preserved, 
 that are known to have been made at other cities of the 
 empire, besides those at King-te-ching, and as well as in 
 Japan, long prior to the Christian era. As the wants of 
 mankind increased, in like manner would their endeavours 
 to invent means for their supply. There is no clue to the 
 precise date of the introduction of Tea Ware among the 
 domestic utensils of this people, though there cannot be 
 any doubt that their Manufacture would quickly become 
 general, on their convenience and utility being fully ex- 
 perienced. I cannot believe yet, that this was the period 
 of the origin of this Art among this people. It certainly 
 must have been earlier, because it could not immediately 
 rise to that state of excellence in quality and perfection in 
 manipulation adapted to render it of importance at court. 
 Though I am ready to confess, we need not wonder that 
 this people did so soon arrive at the admitted superiority 
 of their productions, and the perfection of their porcelain, 
 when we consider that they have the indispensable earths 
 for their purposes and all other materials, clays or minerals, 
 of recent date discovered as useful by the researches of 
 Europeans. 
 
 The fact that close examination of known early speci- 
 mens, and of others very recently manufactured, in every 
 point of comparison present to the inspection similar 
 characteristic qualities and properties, by indicating that 
 
 *Dr. Johnson gives us the etymon of porcelain, pour cent annees, pro- 
 bably because of the statements that the period of one or two centuries is 
 required to weather the clay for the Chinese potters. Others derive it from 
 the Latin name of the Venus shell, concha porcellana, of the genius Cypraea, 
 partly because the polished exterior of the ware approaches to the beautiful 
 rich surface of the shell, whose peculiar hinge suggests the name, and be- 
 -cause only by females was tea- ware first used in Europe. Because of the 
 -obscenity of the Latin term, the country supplies the name CHINA. 
 
394 CHEMISTRY OF POTTERY. . 
 
 no alterations whatever have been made in either the 
 materials or processes, may be supposed to militate against 
 the opinion, that, during a long period the Manufacture in 
 this quarter was progressively improving to its admitted 
 station on the scale of excellence, and more especially as 
 there are many known ancient specimens, greatly superior 
 to those usually vended at modern sales ; whence comes the 
 observation, said to be of Chinese origin, that the former 
 Manufacture excelled that of the present day. But, in 
 support of the opinion, there is brought another fact, that 
 although the Chinese potters might (and there is every 
 degree of probability that they did) by accident discover 
 and employ the debris of the two families of felspar 
 rocks, kaolin and petuntse, in forming their ware, yet 
 certainly they did not in like manner discover the appro- 
 priation of those substances as at present practised. Many 
 attempts, accompanied with varied success, and requiring a 
 long period of time, assuredly would have been made 
 before the discovery of the proportions requisite to make 
 porcelain, and a much longer time to invent the processes 
 by which the rocks are reduced to a workable state. Every 
 observer must have noticed that the very nature of prac- 
 tice in any of the Arts of Life is the progress to perfection in 
 processes, and to excellence in properties. The Chinese 
 assertion of the superiority of the ancient Manufactures 
 will be allowed by only those who are not aware that the 
 like materials and processes are still employed, and that 
 the natives do not hesitate to employ the most monstrous 
 falsehoods to deceive those strangers with whom they have 
 dealings. That most choice specimens have been obtained 
 from places where they had been buried or hidden several 
 centuries, is readily acknowledged ; but those persons who 
 recollect the frequent intestine commotions which have 
 disturbed the Celestial Empire, will regard these specimens 
 as with greater probability hidden, because of their value, 
 by their owners in some civil war and forgotten. The best 
 specimens now manufactured contradict the assertion ; and 
 
OBIGIN AND PROGRESS. 395 
 
 it is a mere chimera to suppose that a long deposition in 
 the ground is indispensable to render the most valuable 
 articles perfectly beautiful and excellent. 
 
 The principal seat of the Manufacture in Britain, the 
 borough of Stoke-upon-Trent, has about 30,000 operatives 
 employed to furnish the requisite supplies of porcelain, 
 flint, and Delft wares for home consumption and exporta- 
 tion to most celebrated places on the globe. We therefore 
 are surprised at the mention that King-te-ching contains 
 500 ovens, and has 800,000 operatives to keep them con- 
 stantly supplied. The number seems immensely large, 
 even though it be admitted that here is supplied the 
 porcelain, most esteemed and excellent, purchased by the 
 Japanese merchants for the European markets, in preference 
 to the porcelains of Fo-kien and Canton, which have 
 depreciated value : and, that the imperial court has ever 
 manifested for this ware a decided partiality and preference, 
 and requires the most excellent specimens to be constantly 
 devoted to its purposes. There is certainly one cause, 
 which possibly may render requisite such an immense num- 
 ber of work-people (the writer of the article " Porcelain," 
 in Kees' Cyclopcedia, assigns it as that for the enormous 
 charge of the Oriental porcelain): "It rarely happens 
 that an oven succeeds throughout; but it is frequently 
 quite spoiled, so that upon opening it, in lieu of fine porce- 
 lain is found a hard unformed mass, into which both the 
 porcelains and their coffins [the vessels and the seggars] are 
 converted, either by excess of heat, or some ill qualities in 
 the matter." Yet this writer (like many others who seem 
 wishful to regard all of foreign production as super- excel- 
 lent), when comparing this Oriental porcelain with that of 
 St. Cloud, which is infusible, in entire forgetfulness of the 
 above remarks, says : " the China-ware being made of a 
 paste, part of which is made of a substance in itself 
 scarcely possible to be vitrified, bears the fire in yet much 
 more intense degree than ours, and is in no danger of 
 running wholly into glass from it/' Parkes makes an 
 
396 CHEMISTRY OF POTTERY. 
 
 equivalent assertion, and no doubt both imagine they are 
 correct. Let them just reflect on the components of the 
 paste and the glaze, and 'they will readily understand the 
 tremendous heats of the Chinese ovens. 
 
 Satisfactory information has not been obtained of the 
 precise date of this proud conquest of our ancestors the 
 establishment of the Manufacture in the district, now the 
 borough of Stoke-upon-Trent, but that it preceded the 
 introduction of the Saxon tongue etymology clearly demon- 
 strates ; BURSLEM has its name from beinp- the locale of 
 
 O 
 
 the Manufacture ; and the different enunciation of the com- 
 pounded names of the same primary ideas has caused the 
 scribes of the times to vary the orthography, as Bwlward- 
 esloem,, Bwlwardslene, Bwryeardeslyme, Burewardeslime, 
 Barcardeslim, etc. The force of each part of the compound 
 will appear clearly thus : Burn, byrn, a small rill of water, 
 its receptacle being a bwl, bwr, bwc (bowl, burl, bowk); 
 wardes, yeard, cardes, a spot wared, guarded, looked over, 
 (yard, a farm-yard tan-yard, church-yard and garden, 
 quarry, are cognate terms) ; lazm, clay, earth, Icemen, earthy, 
 lemm-faet, the feat in loam, work in clay ; and lyme, lene, 
 lime, are kindred forms. The words then originally signi- 
 fied a vessel to contain water, a guarded spot of land, and 
 the earth of which the vessel was fabricated, and hence the 
 true import of Burslem is the SPOT where is QUARRIED 
 and used CLAY for POTS. The small utensil for conveying 
 drink to the mouth, because of its purpose was named tyg, 
 or the touched pot, corrupted into tot; and the maker of 
 drink-cups was named tyg el wyrthan, workers of tygs 
 (still retained in Saxony). On other etymologies it were 
 invidious to offer any remarks. 
 
 Reasoning on the importance to a nation of the suc- 
 cessful fabrication of valueless earths into vessels of consider- 
 able value, it would be supposed that there would be made 
 great endeavours to discover the materials and completely 
 develop the processes by which to conduct at home the 
 Manufacture of porcelain, similar to that which from Japan 
 
ORIGIN AND PROGRESS. 397 
 
 and China found its way into the western states of Europe ; 
 and, being the ornament of sumptuous tables, and the 
 admiration of persons of opulence and taste, was increasing 
 in demand. And yet the broad tablets of history show the 
 negative of such surmises. Such had been the prevalence 
 of ignorance and barbarism ; the inability of the poor, 
 and the indifference of the rich ; the indolence of the in- 
 genious, and the apathy of the active ; the vigorous pursuit 
 among the European states of the Arts of destructive war- 
 fare, and the negligence of those of social comfort and 
 peace, as present the lamentable facts, that, during sixteen 
 centuries of the Christian era, in which regard to the 
 injunctions and precepts of the Divine Founder should and 
 would have promoted public prosperity, and increased the 
 sum of human happiness, all attempts whatever for the 
 above important and useful purposes were either altogether 
 disregarded, or remained completely unsuccessful, even 
 though incessantly aided by the almost incredible efforts 
 of the Jesuit missionaries in the east.* 
 
 * The indifference of nations, however, to their best interests, did not pre- 
 vent the appearance of individuals, who, disregarding every obstacle, aimed at 
 accomplishing some important addition to the stock of public wealth. The 
 following worthies are connected with earthenwares : 
 
 LTJCA BELLA RoBiA, of Florence, born in 1388, afterwards a goldsmith and 
 statuary, manufactured of terra cotta invetriata, or glazed earthenware, of 
 good quality, and agreeably to the fancy of the purchaser, at pleasure white, 
 brown, blue, green, or yellow, vessels of the kinds needful for domestic pur- 
 poses ; and in relief, busts and figures of saints, in truly excellent style of 
 sculpture, and in our day numerous in the churches of his native city. The 
 workmanship does great credit to the talents of the artist ; and the composition 
 of the materials, though certainly the result of accident and observation 
 without the helps of theory, seems as perfect and equivalent as if there had 
 been employed the fullest attention to the laws of chemical combination. 
 
 CASTEL FRANCO, in 1510, manufactured, at Faenza, excellent Majolica, 
 the Italian name for Earthenware named Fayance by the French. Many 
 of his productions were ornamented by the pencil of Raphael (according to- 
 the information given me by the late Jacob Warburton), and the specimens 
 yet preserved in many collections cannot fail to excite surprise that so few 
 improvements have been made, and such a long intervening series of years has. 
 
398 CHEMISTRY OF POTTERY. 
 
 While engaged in the fruitless attempt to introduce the 
 tenets of the church of Rome among the inhabitants of the 
 extensive empire of China, into whose estimation they 
 
 elapsed to bring the Manufacture to its present state in the several European 
 nations. 
 
 BERNARD DE PALISSY, neglected during his career, but now named only 
 with exultation, born at the close of the fifteenth century at Agen, in France, 
 versed in the chemical knowledge of that age, and with his acquirements 
 uniting both superior talents and industry in the Manufacture of fayance, and 
 especially its glaze, made great improvements by the most astonishing per- 
 severance. Of humble origin, and employed as a draughtsman and land-sur- 
 veyor, accident presented him with a cup of Italian fayance, whose glaze and 
 beautiful enamel-painting caused the powers of his mind to be devoted to 
 produce ware equally excellent ; and only to his own indefatigable energy and 
 unquenchable thirst for full accomplishment does he owe the success which 
 ultimately brought this Manufacture into celebrity in France, and secured to 
 himself fame, honours and independence. The 'narrative of his labours, sacri- 
 fices, and privations is a most instructive piece for a person commencing the 
 study of useful sciences ; and most sympathetically do I respond to many of 
 the bitter remarks he so pertinently makes. As a self-taught painter his 
 industry and efforts were inadequate to provide for his family ; and during the 
 anxiety consequent on the failures, to which "hope told a flattering tale," the 
 idea of advantages from knowledge of the fabrication of such ware took full 
 possession of his thoughts. Imagining that whatever trouble or difficulty 
 might attach to the acquisition, the termination of his miseries would ensue 
 from his success, he determined to assiduously employ every moment he could 
 spare, every effort he could make, and all the means he could obtain, however 
 limited in quantity and amount. One of his productions supplied funds to 
 commence his processes, but their results proving entire failures, he was thus 
 more reduced, and had the additional annoyance of the remonstrances of 
 relatives, who deemed his design chimerical, and the earnest entreaties of his 
 wife that he would relinquish his ruinous project. Persuaded, however, in his 
 own mind that success was within his reach, at exorbitant interest he borrowed 
 money from parties willing to lend, and which he expended without any other 
 than mere trifling success. Now he was necessitated to give part of his 
 clothes to induce his assistant to continue his aid ; and failing of funds to pur- 
 chase fuel, his chairs and tables were substituted and consumed. His wife and 
 family justly complained of the privations they endured, and his own feelings 
 were constantly agitated by witnessing these, and failure of his researches, 
 during about sixteen years ; yet his common cheerfulness prevented his 
 friends becoming acquainted with his really destitute condition. And at 
 length complete success crowned his efforts ; the productions of his ingenuity 
 became of national importance, and secured to himself and family opulence 
 and distinction. 
 
ORIGIN AND PROGRESS. 399 
 
 might successfully ingratiate themselves, the missionaries of 
 the Society of Jesus had to adopt every method, and resort 
 to every practice, short of sin and infidelity ; but persons 
 acquainted with the history of that society know, that an 
 object regarded as requisite was never relinquished in con- 
 sequence of obstacles being presented. The Manufacture 
 of porcelain, as practised in China, was a desideratum to 
 France, and the veil thrown over all the processes had been 
 impenetrable by every effort of the Dutch and English 
 merchants. The development, however, was undertaken 
 by one of the above-mentioned society, who is entitled to 
 grateful remembrance as a benefactor to Europe at large. 
 With only a very limited knowledge of the construction of 
 machinery, and a restricted acquaintance with the proper- 
 ties of mineral productions even had the Oriental pro- 
 cesses been in any way adapted to suggest rather than to 
 retard improvements in those of Europeans his descrip- 
 tions are defective in precision, yet only perhaps because of 
 misinformation. The indefatigable friend of his country, 
 the Father FRANCIS XAVIER DE ENTRECOLLES, during a 
 long residence at King-te-ching and its vicinity, by the 
 suavity of a mild deportment and amiable manners eluded 
 the jealous vigilance usually exercised towards strangers, 
 and by much intrigue, unparalleled assiduity, and a very 
 bland and insinuating address, secured the friendship of 
 some of the less suspecting of the potters, was favoured 
 with opportunities to witness the processes and manipula- 
 tions of the Manufacture, and obtained ample specimens of 
 the two chief materials, the kaolin and petuntse. He 
 fully detailed all the particulars in a letter, dated Jauchew 
 (or Jaotcheou), Sept 1,1712, which he transmitted, with the 
 specimens, to the Jesuit Father Orry, of Paris, by whom 
 the information was quickly spread ; and to more generally 
 diffuse it, Crosier published the details in his General 
 Description of China. 
 
 The return from the east of the few warm-hearted 
 enthusiasts who had engaged in the Crusades, made those 
 
400 CHEMISTRY OF POTTERY. 
 
 nations to which they belonged better acquainted with- 
 science. They had also imbibed the error of transmutation, 
 and caused all the known metals to be tortured in every 
 way likely to supply the precious metal sought. In the 
 different cities of Europe the practices of some alchemist* 
 those labourers in the ardent laborato^ of metallurgy 
 had introduced the Manufacture of Common Stone 
 Ware, having proved that it only could with security be 
 employed in the intense heats to which their furnaces 
 were occasionally raised, and which a judge of no ordinary 
 ability, Macquer, asserts, " is the most perfect pottery that 
 can be, possessing all the essential qualities of the finest 
 Japanese Porcelain." To render these vessels more easy to 
 be cleansed, and retentive of any chemical compounds or 
 preparations, without being permeated thereby, vitrification 
 of the surface was affected by fusing the silica in combina- 
 tion with soda during the decomposition of common table- 
 salt. In this, as in many other of the processes, with 
 little real chemical knowledge of the properties of sub- 
 stances, nor any exemplars of what they wished to produce,, 
 the simultaneous endeavours of several persons to introduce 
 something new obtained some partial success: a close 
 investigation of one subject frequently reflected additional 
 light on some other; results, altogether unexpected, were 
 presented to notice, and often an incident, comparatively 
 trivial, occasioned a discovery of paramount importance 
 
 Prior to 1700 a professed alchemist from Switzerland 
 had frequently visited the shop of a druggist in Magdeburg 
 for the various articles required in his researches for the 
 Elixir Vitce, the Philosopher's Stone, and the Powder of 
 Projection. Like most of his compeers in the delusive task, 
 blinded by the avarice which stimulated perseverance in 
 the unproductive labours, he seems to have altogether over- 
 looked, or entirely disregarded the numerous intimations 
 given by the processes that the attention was courted to 
 transpiring facts, from which valuable and truly important 
 discoveries have since rewarded the patient observations and 
 
ORIGIN AND PROGRESS. 401 
 
 assiduity of minds better regulated to the consecutiveness of 
 scientific investigations. The druggist had an apprentice,, 
 named John De Botscher (mentioned already at page 5), 
 whose kind attentions and repeated manifestations of readi- 
 ness to oblige the alchemist, even at some personal inconve- 
 nience, so won the regard of the enthusiast as to induce 
 him to communicate in detail correct information relative 
 to the customary processes and manipulations in chemistry, 
 which were regarded as indispensable to the full effecting of 
 transmutation. About 1700 the alchemist fell a victim to 
 his unhealthy experiments, like many another engaged in 
 chemical researches, and the young man became possessed 
 of his papers, and retained them for his own purposes, at an 
 age the most critical for the proper formation of character. 
 Dishonourably disregarding the connection between his 
 master and himself, and indifferent to the possibility that 
 himself might become a houseless wanderer, elated with his; 
 possession of the treasury in which were deposited the im- 
 portant secrets, at that time the objects of such assiduous 
 labour to the initiated, and buoyed up with the supposition, 
 that both health and opulence were now within his com- 
 mand, he absconded to Berlin, and announced his acquisi- 
 tions and purposes for the benefit of the -citizens. Leibnitz: 
 says : ' ' Without my being able to explain how it came to 
 pass, I know he took to gold-making, and revived the almost 
 expiring hopes of the alchemists by extraordinary proofs of 
 his skill. Several eye-witnesses aver, that in their presence,, 
 as he was about to leave his master, he threw thirteen pieces 
 of copper money, which one of those present gave him, into 
 a melting-dish, and after they were melted, he added to 
 them a piece of some substance that resembled dark-coloured 
 glass, and almost immediately afterwards poured out of the 
 melting-pot a piece of fine gold, equal in weight to the 
 money employed. This took place before he received in- 
 struction from the celebrated Tschernhausen, in Dresden." 
 On his master discovering the place of his apprentice's re- 
 treat, justly considering himself entitled to the advantages 
 
 2 u 
 
402 CHEMISTRY OF POTTERY. 
 
 resulting from his industry, and hoping to derive opulence 
 from the alchemist's papers, he pursued the fugitive, had 
 him apprehended, and before the judicial authorities of 
 Dresden stated his claims, and urged the committal of the 
 young alchemist again to his care and protection. His 
 journey, however, ended in complete disappointment. The 
 reigning prince had some peculiar views of the whole affair; 
 whether he indulged the hope of ultimately obtaining from 
 the youth's possession of the secret or not, he hesitated to 
 decide the case, and seems not to have been disposed 
 entirely to neglect so favourable and remarkable an op- 
 portunity for readily enriching himself as was thereby 
 unexpectedly presented. Under the pretext of more fully 
 considering the merits of the case, he detained De Botscher 
 in the castle of Koningstein, but gave to the keepers secret 
 instructions to supply him with all kinds of materials he 
 might need in whatever experiments he might feel disposed 
 to make, either for employment of his time against ennui, 
 or in pursuit of his chimerical researches. In this condition, 
 at only the expense of his own labour, and the cost of the 
 prince, he had ample opportunity and sufficient leisure to 
 make memorandums of the compounds, proportional quan- 
 tities, and results, in his multiplicity of experiments and 
 mortifying failures. Yet he had not opportunity to either 
 mal-appropriate or destroy the least portion of the products. 
 Some specimens of metals obtained during the course of his 
 researches, instead of inducing the prince to liberate the 
 detenu, prompted the more his avaricious expectation of 
 ultimate successful results. De Botscher's crucibles failed 
 under the extremely high heat of his furnace, which he 
 deemed requisite to fuse some of the minerals. The fabri- 
 cation of others more refractory engaged his attention, and 
 without determined knowledge of the qualities of minerals 
 and stony masses, he mixed and remixed at random for 
 some time. However, the period of his liberation came 
 more quickly than he might have expected, however highly 
 desirable he might consider it. On one occasion, ignorant 
 
ORIGIN AND PROGRESS. 403 
 
 of the natural qualities of the substances, and of their 
 chemical tendencies when affected by high temperature, he 
 mixed some minerals whose natural properties are exactly 
 similar to those of the kaolin and petuntse employed by the 
 Chinese in the Manufacture of porcelain, and most unex- 
 pectedly he found his crucibles, formed of this compound, 
 refractory in the most intense heat he could command. 
 And to his great surprise and gratification, he found like- 
 wise what his most ardent fancy had never once imagined, 
 the crucibles, when cold, were of a pale flesh-colour, semi- 
 vitreous, semi-transparent, and so compact and firm as to 
 receive from the lapidary's wheel a polish and lustre equal 
 to that of the best glazed porcelain. The repetition of his 
 processes satisfied him of the importance of the discovery, 
 thus accidentally made, to the commercial resources and 
 revenues of the country ; and while prudence urged to the 
 concealment of the substances and proportional quantities, 
 he had sufficient wisdom to immediately discontinue all 
 pursuits of the objects for which he had been primarily 
 incarcerated, and devote all his mental energies to the per- 
 fecting of the discovery which now presented itself, as likely 
 to be incalculably more valuable to himself, and much more 
 useful to society, by promoting individual industry, and so 
 inducing comfort and prosperity. The apartments of the 
 Japan palace at Dresden now contain numerous specimens 
 of the kinds of ware he made, while he was busily engaged 
 in perfecting the composition of the white real porcelain, in 
 imitation of the imported productions of China and Japan. 
 The prince himself had both the honesty and honour to avow 
 the debt due to the youth who had thus introduced a sub- 
 ject of inestimable value to his dominions, not indeed for 
 success in alchemy, transmuting the metals into gold, but 
 for transmuting the rocks into elegant vessels adapted for 
 both usefulness and ornament ; for transforming the mire 
 and the clay into a valuable article of commerce ; and to 
 award, as a compensation, a patent of nobility with ample 
 possessions to support the dignity. The white porcelain, 
 
 2 D 2 
 
404 CHEMISTRY OF POTTERY. 
 
 the Manufacture whose establishment was the ultimate 
 result of the discovery, was the only kind made during the 
 life of De Botscher, and merely a little improved was con- 
 tinued for the private advantage of the king of Saxony ; 
 but about three years after his death, the Manufacture of 
 coloured porcelain was successfully introduced, and the excel- 
 lence of the productions has secured them a value rivalling 
 the most choice specimens from the celestial empire. The 
 other European nations were no otherwise benefited by 
 this discovery, than as regarded the stimulus given to the 
 exertion of genius and research. For with a jealousy too 
 common, yet not the less to be regretted, to preserve veiled 
 in impenetrable secrecy every process for the Manufacture of 
 the Dresden porcelain, the place selected as the arcanum 
 for their seclusion was the ancient castle of the Albrechts- 
 berg, situate on a rock more than eighty feet above the bed 
 of the river Elbe, at Meissen, near Dresden ; and here, in 
 cells, all the persons employed in the processes were as 
 completely immured, as if crime had been the cause of their 
 incarceration. 
 
 The announcement of De Botscher's, perhaps we ought 
 to say, invention, and the remarkable success which at- 
 tended the Manufacture of the Dresden porcelain, commu- 
 nicated such impetus to the operations, and so stimulated 
 the researches of the potters of Britain and France, that a 
 great variety of productions resulted, each differing from 
 the others, and presenting a beautiful appearance on the 
 exterior; but all, more or less, obviously deficient in the 
 qualities essential to real porcelain, and much surpassed in 
 excellence by the productions of Dresden, as well as those 
 of China and Japan; and because of their open grain and 
 texture, as also of their ready fusibility at a moderate degree 
 of heat, distinguished among connoisseurs by the general 
 appellation of Soft or False Porcelains. 
 
 The arrival of the specimens sent from China by 
 D'Entrecolles, was regarded as of such importance to the 
 manufacturing interests of France especially, and was the. 
 
ORIGIN AND PROGRESS. 405 
 
 cause of such expressions of satisfaction, that without the 
 least delay to ascertain their components, relative propor- 
 tions, and chemical qualities, or whether the researches of 
 the mineralogists would be successful in discovering that 
 France (as was proved in 1739) possessed in the quarries of 
 Alen^on and St.Yrieux, near Limoges, the same family of 
 minerals which supply the kaolin and petuntse, and which 
 would render less difficult the perfect imitation of the 
 admired oriental productions, Reaumur, the amiable, intelli- 
 gent, philosophic, and celebrated friend of the Arts, devot- 
 ing the greater portion of a long life to benefit his country, 
 with true patriotism, at St. Cloud immediately commenced 
 a series of experiments, which he iiidefatigably pursued, to 
 develop the essential properties of porcelain, ascertain the 
 agreement or difference of those of Dresden and China, and 
 elucidate the most felicitous methods for establishing a rival 
 Manufacture. He found Japan porcelain, in grain and 
 texture, close and compact; in appearance, shining, smooth, 
 and infusible in any heat he applied ; De Botscher's por- 
 celain, not granular in texture, but more compact than that 
 of Japan, smooth, and vitreous like enamel: After much 
 labour and frequent disappointments, his reasonings were 
 fully demonstrated by the characteristic properties of the 
 Japan porcelain : when a substance which is, per se y fusible 
 at a known temperature (as he found the petuntse), is 
 mixed with a determined proportion of another substance, 
 per se, infusible at any temperature (as the kaolin proved), 
 the fusible component flowing by the heat, which even 
 much increased does not alter the infusible, there will be 
 formed a vitrified compound substance, such as is the Japan 
 porcelain. To verify these reasonings, he mixed different 
 proportions of the Chinese minerals in their crude, and also 
 in their prepared states, subjected them to proper baking, 
 and had the great satisfaction to find certain of them, in 
 grain and texture, much similar to the Japan ware. The 
 results suggested the improved French porcelain, in grain 
 less close and fine than that last mentioned, with a fracture 
 
406 CHEMISTBY OF POTTERY. 
 
 like line sugar ; and, formed of the earths, whose announce- 
 ment is thus made in the Transactions of the Academy of 
 Sciences, Paris (1739): " We have in Europe substances of 
 the very same nature as the oriental petuntse and kaolin, 
 and capable of being worked into a porcelain equally beau- 
 tiful and fine." The experiments had been published in 
 those Transactions in 1729, ten years after the death of 
 De Botscher. Ultimately they caused the establishment of 
 the deservedly celebrated Sevres Manufactory, under royal 
 patronage, where are produced specimens of Art which will 
 bear the most scrupulous comparison with the choicest ob- 
 tained from Dresden and China, the directors being devoid 
 of fear of expense, and by restrictions on private Manu- 
 factories, secured from the effects of competition, while 
 availing themselves of every important suggestion by persons 
 of scientific acquirements adapted to promote improvement. 
 Reaumur, in 1739, also published the process by which he 
 so devitrified glass as to form the peculiar substance 
 which is named, not for its properties, but its appearance, 
 Reaumur's Porcelain, very useful and durable for fabri- 
 cating vessels in many of the processes of the laboratory. 
 His early attempts were on mixtures of saline fluxes with 
 vitrescent minerals ; and he imbedded in plaster of Paris, 
 or sand, green bottle-glass, subjected it some time to a heat 
 below the fusing point, and found the specimens semi-trans- 
 parent, scintillative with steel, and uninjured by sudden 
 transitions from high heat to cold, as well as in many 
 properties resembling Japan porcelain. 
 
 Scarcely need I mention, that on the principles already 
 stated a great variety of different wares may be readily 
 fabricated of earths not possessing equal fusibility. The 
 facts are evident in the number of Manufactories : St. Cloud, 
 Fauxbourg St. Antoine, Paris, Chantilly, Villeroi and 
 Orleans ; Naples, Florence, Vienna, Frankendal, and 
 Berlin. Yet the connoisseur easily distinguishes the 
 Oriental from these, which derive their beauty from near 
 approach to vitrification, and being allowed to cool at the 
 
ORIGIN AND PROGRESS. 407 
 
 time when a little longer duration of the high heat would 
 have completely fused them into glass or slag; the other 
 (and partially so those of Berlin and Vienna, which are of the 
 same materials as that of Dresden), having one component 
 scarcely possible to be vitrified, endures the intense heat 
 which completely vitrifies the other component, without 
 becoming glass. 
 
 The following facts will suggest an idea of the anxiety 
 felt in Britain on this interesting subject: One of the 
 members of the Royal Society of London, Dr. William 
 Sherrard, visited Paris about the time of the publication of 
 De Entrecolles's letter, and he quickly communicated the 
 contents thereof to that celebrated assembly, and enriched 
 their museum with specimens of the native minerals, and 
 of the prepared petuntse and kaolin. How many of the 
 chemists and mineralogists of Britain have availed them- 
 selves of the opportunity for careful examination, to assist 
 them in their researches whether and where any minerals 
 with similar properties were to be found in Britain, we have 
 no means whatever to ascertain. And : That notorious 
 literary impostor, the French Jesuit, George Psalmanazar, 
 attempted to pass for a native of the island of Formosa, 
 and with such temporary success, that he obtained a very 
 considerable sum as a gratuity from a potter in the vicinity 
 of London, for permission to use his name in a design then 
 contemplated, an attempt at the Manufacture of porcelain ; 
 which failed, and deservedly, because deficient in all the 
 essential properties of real porcelain, but was pompously 
 announced, and for a short time obtained considerable cele- 
 brity, as " A curious white Formosan work, made agreeably 
 to directions obtained from a native of that island." Not 
 these attempts, but all others made by our countrymen in 
 England, until 1$20, were unsuccessful in producing real 
 porcelain, owing to the chemical properties of the minerals 
 used by the Chinese being very imperfectly detailed ; and 
 their existence in immense quantity, and truly excellent 
 quality, having remained till that time undiscovered. But 
 
408 CHEMISTRY OF POTTERY. 
 
 such as was the numerous varieties of soft porcelain, for 
 merit in the workmanship I shall be excused for denying 
 any inferiority whatever. I shall insist on prior claims of 
 our artisans for improvements in the processes and dex- 
 terity in the various manipulations, decidedly superior to all 
 others ; and for our artists, that skill and taste in ornament 
 which at the lowest estimate is equal. The productions of 
 the celestial empire, in scarcely any particular instance, 
 will bear comparison neither will those of Dresden, Sevres, 
 and Berlin be disparaged by it, for chasteness of model, 
 grace, and symmetry of figure, and elegance of execution 
 with the productions of Derby, Worcester, Coalport, or 
 the (new) Borough of Stoke- upon-Trent ; and the really 
 uncouth figures and unmeaning scenes, delineated to em- 
 bellish the oriental porcelain, the connoisseur will not place 
 in competition, for delicacy of colouring and accuracy of 
 tracing, with the natural landscape, the assorted and taste- 
 ful bouquet, and the grouped animals pleasingly depicted, 
 so elegantly painted on British porcelain and flint wares. 
 The celebrity and success of the two royal Manu- 
 factories of Dresden and Sevres excited the cupidity of 
 Frederic II. of Prussia ; who, from political motives, and 
 a conviction of the importance of the Manufacture, about 
 1762 first established the Royal Manufactory of Porcelain 
 at Berlin, for the private advantage of himself and his 
 successors. To ensure its success, and extend its opera- 
 tions, he embraced every opportunity that was presented. 
 His conquest of Saxony was subservient to the expatria- 
 tion of many of the most clever and expert workmen in 
 the Manufactory at Meissen, near Dresden, that their pro- 
 ductions for excellence, elegance, and beauty, might rival 
 in celebrity those of Dresden and Sevres. He presented to 
 -each German Prince and Sovereign complete services for 
 the toilet, breakfast, dejeune, dinner, and dessert, the 
 more extensively to diffuse the knowledge of their place 
 of fabrication. And the better to ensure employment for 
 the 500 persons engaged in the processes, he restricted the 
 
ORIGIN AND PKOGRESS. 409 
 
 Jews resident in any part of his dominions from entering 
 into the marriage state until each man had obtained a 
 certificate from himself, which was only ^granted on the 
 production of a voucher from the director of his Manu- 
 factory, that porcelain to a given amount had been then 
 purchased, and that there was a reasonable cause for 
 claiming such indulgence. Of course, the Jews more 
 readily disposed of their purchases than the general dealers, 
 and the device was attended with much success. This por- 
 celain remains inferior to those it was intended to rival, 
 .though it is proper to mention that in Berlin are other 
 Manufactories ; and at those of MM. Fielner and Gormann 
 has been introduced very successfully the fabrication of 
 earthenware ornaments for churches, many of which adorn 
 the sacred edifice of St. Stephano.* 
 
 Of the progress of the Manufacture in Holland I am 
 not in possession of any information. But that it was not 
 stationary, and that among the Dutch potters were some 
 master-minds, will, I think, clearly appear from the 
 statement now to be made. From Nuremberg, in Holland, 
 two brothers, named Elers (a name connected with the 
 ^chemical researches of that period), followed their country- 
 man, William III, in 1688. And quickly must they have 
 located themselves in the immediate vicinity of the Manu- 
 facture in the county of Stafford, for prior to 1690 they 
 
 * The process is the following : Into the plaster moulds the soft clay is at 
 different times introduced in small quantities, and into the various cavities 
 carefully pressed with the fingers. After the requisite quantity of clay has 
 been thus gradually forced into the mould, by strong mechanical pressure 
 applied to the entire mass, the clay is condensed, yet forced into the most 
 delicate lineaments and indentations; and to ensure yet greater cohesion, 
 which is indispensable that it may sustain the high heats of the furnace in 
 baking equally and uniformly, in the centre of the thicker parts of each 
 figure are carefully placed round pieces of white wood. These very durable 
 and elegant ornaments, thus readily formed, exhibit a firmness of substance, 
 accuracy of outline, and delicacy of execution, which even the best sculptors can 
 scarcely equal, not to say excel, in their operose labours on the finest marble. 
 
410 CHEMISTRY OF POTTEEY. 
 
 were busily engaged in their particular branch, in the- 
 secluded spots of Dimsdale and Bradwell, both within two 
 miles of Burslem, but from which the former, not at all, 
 and the latter scarcely is discernable ; and equally without 
 annoyance from the potters of Red Street. No inquiries 
 now avail to show how the Manufacturers, born on the 
 spot, in a manner, had neglected to husband well their own 
 resources; and, independent of the supply of coal, how 
 these strangers happened to be the first discoverers of the 
 peculiar kind of clay in this neighbourhood (and veins of 
 which are still kept open for supplying the same, fine in 
 grain and dark in colour, for the mocha dip, in the field 
 west of Brownhill's toll-gate, and in the path through 
 Bradwell Wood near Chatterley), which would be so suc- 
 cessfully used in the Manufacture of ware that would 
 imitate the oriental dry body or unglazed red porcelain. 
 But in 1690, from the native clays of Bradwell and 
 Chesterton, carefully levigated and passed through fine 
 hair-sieves, and then artificially evaporated, they were 
 manufacturing, to considerable extent, an improved kind 
 of red porcelain, and with manganese added to the clays, 
 of black, a knowledge of whose components was the origin 
 of Wedgwood's Egyptian. The specimens yet preserved, 
 by their excellence in grain, texture, and shape, although 
 the ornaments are truly grotesque, will ever manifest the 
 skill and success of the foreigners. Their extreme pre- 
 caution to keep secret their processes, and jealousy lest 
 they might happen to be witnessed accidentally by any 
 purchaser of their wares making them at Bradwell, and 
 conveying them over the fields to Dimsdale, to be there 
 sold, being only two fields distant from the turnpike-road ;. 
 and having some mode of communication (believed to be 
 earthenware pipes like those for water laid in the ground), 
 between the two contiguous farm-houses to intimate the 
 approach of persons supposed to be intruders caused them 
 to experience considerable and constant annoyance. In vain 
 did they adopt measures for self-protection in regard to. 
 
ORIGIN AND PROGRESS. 411 
 
 their manipulations, by employing an idiot to turn the 
 thrower's wheel, and the most ignorant and stupid work- 
 folks to perform the laborious operations ; by locking up 
 these persons while at work, and strictly examining each 
 prior to quitting the Manufactory at night ; all their most 
 important processes were developed and publicly stated 
 for general benefit (as already detailed, p. 249). Mortified 
 at the failure of all their precautions, disgusted with the 
 prying inquisitiveness of their Burslem neighbours, and 
 fully aware that they were too far distant from the prin- 
 cipal market for their productions, even had not other 
 kinds of porcelain been announced, which probably would 
 diminish their sales, about 1710 they discontinued their 
 Staffordshire Manufactory, and removed to Lambeth or 
 Chelsea (where is, at this day, a branch of the family), and 
 connected the interests of their new Manufacture with those 
 of the glass Manufacture, established in 1676 by Venetians, 
 under the auspices of the Duke of Buckingham. Others, 
 however, have., stated that their removal was consequent 
 on misunderstanding and persecution, because their oven 
 cast forth such tremendous volumes of smoke and flame 
 during the time of glazing, as were terrific to the inhabi- 
 tants, of Burslem, and caused ail its (astonishing number of 
 eight] master potters to hurry in dismay to Brad well.* 
 I think my readers will smile at the affair, when informed, 
 that at this date, or 1707, the numbers were so great as to 
 have twenty-four paupers in the whole parish nine aged 
 men, eleven widows, and four orphans to whom was paid 
 monthly the large sum of three pounds four shillings and 
 one halfpenny ! towards which one pound ten shillings 
 
 * Had this relation been connected with the then close and exclusive policy 
 of the neighbouring borough of Newcastle, I should the less have been sur- 
 prised ; for, half a century afterwards, the corporation acted an equally unwise 
 part, in proscribing the Manufacture in the limits of its authority. Too often 
 does research develop instances in which the existence of many of the Arts of 
 Life has depended on police regulations ; and manufacturing industry, also the 
 
412 CHEMISTRY OF POTTERY. 
 
 and nine pence was provided by Cartwright's legacy 
 {page 414). 
 
 Several writers having ascribed to the brothers Elers 
 the introduction of salt glaze, I shall not be censured for 
 giving the results of my inquiries relative to the same. 
 Without taking into the account, what some would regard 
 as conclusive, that the knowledge of glazing earthenware 
 by means of salt, and its kindred substance, soda, was 
 current in Britain, not merely amongst potters as proved 
 by these remarks, extracted from Dr. Plott's Circular on 
 his projected Itinerary for collecting Materials for his 
 Works on the English Counties, in which, with other- 
 valuable suggestions he states, that he should particularise 
 "all such herbs as are of use in trade: as wold for dyeing, 
 kali for glass-works, fucus maritimus or quercus maritima, 
 which grows plentifull} T in the Isle of Thanet ; they burn it 
 to ashes, and then it is called kelp, which is put into barrels 
 and carried over to Holland, with which they glaze all their 
 earthenware," and which may well be regarded as known 
 to the potters of Burslem and its vicinity there are 
 proofs, by specimens at this day well stored, that about 
 1680, Palmer, at Bagnall and in Burslem parish, Adams, 
 in Holden Lane, and Wedgwoods, of Green Head and of 
 Brownhills, glazed their ware with common salt and a small 
 quantity of litharge. This was ten years anterior to the 
 brothers settling at Bradwell. The practice is, by tradition, 
 ascribed to the following occurrence: At Mr. Joseph 
 Yates', Stanley, near Bagnall, five miles east of Burslem, 
 the servant was preparing, in an earthen vessel, a salt ley 
 for curing pork ; and during her temporary absence the 
 liquid boiled over, and the sides of the pot were quickly red 
 
 manufacturer's welfare, have been rested on the frail basis of the caprice of a 
 magistrate. Driven by ignorance, prejudice, jealousy to a distance from 
 materials, workmen, or market, some manufacturers continue to endeavour to 
 surmount the obstacles which oppose* their progress and maintain a disad- 
 vantageous struggle with the difficulties of their situation. 
 
ORIGIN AND PROGRESS. 413 
 
 hot from the intense heat; yet when cold, were covered 
 with an excellent glaze. The fact was detailed to Mr. 
 Palmer, potter, of Bagnall, who availed himself of the 
 occurrence, and told other potters. At the small Manu- 
 factories in Holden Lane, Green Head, and Brownhills, 
 salt-glazed ware was soon afterwards made, and was in 
 practice when the brothers Elers settled at Bradwell. The 
 facts had long been known that, on being cast into a 
 fire (common table-salt) chloride of sodium is decomposed, 
 and by causing a more rapid fixation of oxygen the heat 
 is much increased : also, that when it was mixed with sand 
 and exposed to considerable heat, a vitrescent substance 
 was the result. These facts suggested the trial, which 
 proved successful, that, when the potter's oven had been 
 raised to the proper temperature, which adequately con- 
 tinued would dissipate the water held by the alumine, if 
 salt were introduced, not only would the heat be much 
 raised, but the alkaline vapour diffused through the oven 
 by the flame would combine with the silica on the sur- 
 face of the vessels, and by semi -fusion form thereon a 
 covering of durable glass, the chemical combination of the 
 proper quantities of silica and alkali leaving the ware with 
 a vitreous appearance. The ovens employed for the pur- 
 pose, being used only once weekly, and the ware being 
 cheap, were large in diameter, and very high, to contain a 
 sufficient quantity to be baked each time to cover all 
 contingent expenses; they were constructed with a scaffold 
 round them on which the fireman could stand, while cast- 
 ing in the salt through holes made in the upper part of 
 the cylinder above the bags or inner vertical flues ; and the 
 saggers were made of completely refractory materials, with 
 holes in their sides, for the vapourised salt to circulate 
 freely among all vessels in the oven, to affect their surfaces ; 
 plenty of specimens yet remain. The oven used by the 
 brothers Elers was taken down within the recollection of 
 oven-builders yet alive (1836), who describe it as adapted 
 to bake choice articles (and salt glazed and dry body 
 
414 CHEMISTRY OF POTTERY. 
 
 wares will not bake together), without holes over the 
 bags, or scaffold around its sides. A long time intervened 
 between Mr. Booth's introduction of fluid glaze and its 
 general adoption in the Manufacture ; and I think we may 
 expect that a longer time would have elapsed between the 
 first introduction secretly by the brothers and its adoption 
 by the chief Manufacturers, not to say the commencement 
 of a suitable kind of ware on which its effects would be 
 most useful. Researches on the spot have supplied only 
 fragments of red, black, and blue (the last probably made 
 by Mr. Cookworthy, or his relative Mr. Marsh, who 
 occupied the farm afterwards), and I regard the perse- 
 cution tale as a mere ruse to cover the sudden removal. 
 Much misapprehension has existed, on the supposed 
 authority of Dr. Plott for the opinion, that the Butter-pot 
 claims priority of date for fabrication ; whereas, unless 
 other pots had been made, there does not seem anything to 
 suggest the appropriation of clay to form receptacles for 
 butter. The relation by Plott certainly is not perspicuous ; 
 but no one can misunderstand- his observations, that "the 
 several sorts of pots, of as many different sorts of clay, 
 in twenty-four hours burnt, they draw for sale to the 
 crate -men, to whom they reckon them by the piece " have 
 regard to other kinds of ware, wholly distinct from butter- 
 pots.* Indeed, had Thomas Cartwright, who died in 1659, 
 made only that kind of ware, even had there been only very 
 
 * Having frequently heard the ingenious device of the Well or Gravy-dish 
 ascribed to Wedgwood, and one or two other celebrated Manufacturers, his 
 contemporaries, at the latter part of the eighteenth century, I was surprised 
 on reading what establishes the fact, that to none of these parties, nor to any 
 modern, is the merit due of the useful invention. However much I may de- 
 light in rendering to every person the due meed of praise, where there is no 
 claim, I am not required to create one. The ingenuity was that of some party 
 long ago commixed with his native earths ; as many specimens, dishes with a 
 similar receptacle, and common in the refectory long prior to the Christian 
 era, have been obtained from Herculaneum and Pompeii, and are at this day 
 preserved in the Studii Museum at Naples. 
 
OIIIGIN AND PROGRESS. 415 
 
 few competitors, I cannot be of opinion that he would have 
 realised property to warrant his then munificent bequest 
 of twenty pounds per annum, to the poor of Burslem for 
 ever. 
 
 There remain in different parts of the district tiles 
 bearing the date 1460, and the specimens, which are pre- 
 cisely similar in quality, density, and appearance, are con- 
 cluded to be contemporaneous. Although of different kinds, 
 they do not present any indications of mixture of materials 
 and change of processes ; but subsequent to that date, by 
 other specimens, we readily trace improvements from the 
 introduction of some fresh material.* The trifling know- 
 ledge possessed concerning the general nature of mixtures 
 appeared to have been excited to further operation by the 
 accidental baking of a small portion of the fine dark red 
 clay, or the aluminous shale ; and they were introduced in 
 varied quantities as they were better known, at the first 
 for the purposes of ornament, and ultimately in the body of 
 the ware.f And when mixing was once commenced, as the 
 
 * An excellent series of specimens are in the museum of the Pottery 
 Mechanics' Institution, supplied out of many thousands by the liberality of 
 that venerable lover of the Art, Enoch Wood, Sen. , Esq. , who, indulging the 
 philosophical idea of collecting whatever remains of the Manufacture were 
 presented to his antiquarian researches, has rendered easy the reference to 
 respective eras, by arranging them, all prior to 1600 together, and all subse- 
 quent in half centuries to the present time, 1836. 
 
 t The spirit of indifference to the gratification which would be afforded to 
 posterity by persons recording their observations of the small commencements 
 and gradual progress of the Manufacture, has caused some trouble to discover 
 and trace the obscure yet ceaseless steps of the appropriation of clays. Most 
 of the natural silicates being with moderate labour and expense accessible, 
 there was needful only some modification. The early potters mixing the clays 
 by bowk-fuls, as 1 + 1, 1 + 2, 2 + 3, 3 + 5, had the baked product to afford 
 the criterion of the utility of the proportions, in accordance with the required 
 kind of ware ; and the least variation in these proportions would vary the qua- 
 lity of the ware, distinguishable by the judicious workman, and thereby raising 
 up a more than usual impediment to the proper dissemination of science. 
 
416 CHEMISTRY OF POTTERY. 
 
 processes varied, the guesses at proportions might have 
 been with almost the fertility of arithmetical progression. 
 On viewing these specimens, and others subsequently fabri- 
 cated, and attentively comparing the progress of the Manu- 
 facture, I am of opinion that it has been, from employing 
 the different materials plentiful in the vicinity, the common 
 potter's clay, as first quarried in the mine ; next, a 
 finer kind, from the bassetings of the coal strata, the 
 aluminous shale ; these afterwards much disintegrated by 
 exposure to the alternations of the atmosphere, and, mixed 
 with water by violent agitation, passed through a hair- 
 sieve upon a sun-pan, or small tank, on whose level 
 surface the mass is by solar heat evaporated to the consist- 
 ence proper for working; next, the finer clays, in like 
 manner mixed and dried, used to ornament the other, and 
 in the sequel entirely superseding all others. In this suc- 
 cession I find the common brown-ware till 1680 ; then the 
 Shelton clay (long previously used by the tobacco-pipe 
 makers of Newcastle, Plott, p. 121), mixed with grit from 
 Baddeley Hedge, by Thomas Miles, of coarse white stone- 
 ware, and the same grit and can-marie or clunch of the 
 coal-seams, by his brother, into brown so?ie-ware ; the 
 crouch-ware was first made of common potter's clay and grit 
 from Mole Cob, and afterwards, the grit and can-rnarle, by 
 A. Wedgwood, of Burslem, in 1690 ; and the ochreous 
 brown clay and Manganese into a coarse Egyptian black, 
 in 1700, by Wood, of Hot Lane; the employment of the 
 Devonshire pipe-clay by Twyford and Astbury, of Shelton, 
 supplied the white dipped and the white stone-ware, from 
 which the transition was easy to the flint-ware, by Daniel 
 Bird, of Stoke; the chalk body-ware, by Chatterley and 
 Palmer, of Hanley, and the queeris-ware of the celebrated 
 Josiah Wedgwood. 
 
 Having now brought to our own homes this interesting 
 Manufacture this honourable, important, and lucrative 
 branch of domestic industry and foreign commerce it only 
 
ORIGIN AND PROGRESS. 417 
 
 remains for me to enable the reader with myself to take 
 familiarly by the hand, and make grateful acknowledgments 
 to its early sons, residents of this district: those worthies 
 of former days, in the infancy of the art noted for fabri- 
 cating earthenware, coarse in quality, because mixing of 
 clay was scarcely if at all known and practised, and rude in 
 workmanship, because adapted only for common uses, yet 
 commencing and establishing the art 011 a permanent basis ; 
 also those master-minds of each era, whose genius, talents, 
 and indefatigable perseverance to introduce fresh materials 
 to supply wherein was deficiency, and to remedy what 
 current knowledge showed to be erroneous ; to invent 
 fresh implements, utensils, and ornaments, superseding 
 the inconvenience experienced have completed the super- 
 structure in a state of excellence worthy its consequence,, 
 and of perfection probably much surpassing their predeces- 
 sor's conceptions of its susceptibility : Mr. Thomas Toft,, 
 for introducing aluminous shale, or fire-brick clay ; Mr.. 
 William Sans, 'manganese and galena pulverised; Messrs. 
 John Palmer and William Adams, common salt and litharge ;. 
 Messrs. Elers, Brothers, red clay, or marie and ochre ; Mr.. 
 Josiah Twyford, pipe-clay ; Mr. Thomas Astbury, flint ; 
 Mr. Ralph Shaw, basaltes ; Mr. Aaron Wedgwood, red lead ; 
 Mr. William Littler, calcined bone-earth ; Mr. Enoch Booth,. 
 white lead; Mrs. Warburton, soda; Mr. Ralph Daniel, 
 calcined gypsum; Josiah Wedgwood, Esq., barytes ; Mr. 
 John Cook worthy, decomposed white granite ; Mr. James 
 Ryan, British kaolin and petuntse ; Messrs. Sadler and 
 Green, glaze-printing ; Mr. Warner Edwards, biscuit- 
 painting ; Mr. Thomas Daniel, glaze enamelling ; Mr. 
 William Smith, burnished gilding ; Mr. Peter Warburton, 
 printing in gold ; Messrs. John Hancock, John Gardner, 
 and William Hennys, lustres ; Mr. William Brookes, en- 
 graved landscapes and printing in colours ; Mr. William 
 Wain wright Potts, printing by machine, and continuous 
 sheet of paper ; and the same gentleman, with Mr. William 
 
418 CHEMISTRY OF POTTERY. 
 
 Machin and Mr. William Bourne, for printing flowers, 
 figures, etc., in colours, by machine, and continuous sheet 
 of paper.* 
 
 * This improvement admits of a delicacy and precision, a clearness and 
 fineness in the work of the pattern, unattainable by the usual mode of printing 
 by hand alike difficult, operose and unhealthy. All this is effected by sub- 
 stituting a cylinder for a flat plate of copper ; worked by apparatus, simple 
 in principle, which simultaneously applies the colours, cleans the engravings, 
 impresses the designs on the paper, and delivers them ready for the trans- 
 ferrers, in a silent and, uninterrupted succession! 
 
[ 419 ] 
 
 CHAPTER II. 
 
 SCIENCE OF MIXING. 
 
 SCIENTIFIC PRINCIPLES OF THE MANUFACTURE. COM- 
 BINATIVE POTENCIES OF THE EARTHS. 
 
 THE Manufacture embraces the compounding of 
 earthy minerals, likewise of metallic oxides, into 
 ductile and colorific substances for the fabrication of 
 EARTHENWARES, utensils receptive and retentive, of 
 the different articles for the various purposes of 
 refection and the toilet, and also ornaments, elegant 
 vases, figures, busts, medallions, etc. The principle* 
 most interesting, and entitled to special attention, 
 because it involves its perfection, being, to unite 
 in the products the excellencies of wholesomeness, 
 neatness and durability. Hence results the 
 
 Problem. How the natural products, alumine and silica, in 
 other and different proportions than at present adopted, can be 
 artificially compounded to form other and better wares. 
 
 By determining all the conditions of this pro- 
 blem, chemistry will establish the processes in a 
 
 constant method; removing whatever is indifferent or 
 
 2 E 2 
 
420 CHEMISTRY OF POTTERY. 
 
 detrimental, and as far as is useful introducing into 
 others whatever has in one been proved advantageous. 
 The silicates which Nature supplies are much exceeded 
 in complexity by the artificial silicates which without 
 any regard to first principles have resulted from the 
 potter's syntheses, which in vain essays to equal the 
 former. Still, as the formation of the latter, by com- 
 pounding the materials agreeably to their respective 
 properties and potencies, similar to equivalent and 
 proportional chemical compounds, will ultimately 
 render the fabricated wares incapable of improve- 
 ment, for this state of simplicity and certainty our 
 enthusiasm incites the hope, as involving important 
 advantages to society. The scientific explorer of the 
 less-frequented recesses of Nature has often, like the 
 voyager when in search of unknown regions, ap- 
 proached very nigh, yet without having had the feli- 
 city to discover an interesting point ; and yet numerous 
 are the discoveries, many of them productive of mo- 
 mentous consequences to mankind, from experiments 
 intended less for the pursuit of an important object, 
 than for the indulgence of amusing curiosity. 
 
 Assuming that there exists, I have attempted to 
 supply, the necessity to facilitate the Manufacturer's 
 acquisition of accurate and extensive knowledge ; to 
 clearly direct him through the most intricate and per- 
 plexing mazes of all the distinctive properties of the 
 different kinds of ware ; determine the precise pro- 
 portions of those materials which are the components 
 of each body, glaze, and colour, and incite the emula- 
 tion which will cause experiments for products similar 
 to those most excellent ; supersede vague incerti- 
 tude and conjectural generalities ; also the prevalent 
 
SCIENCE OF MIXING. 421 
 
 prejudice in favour of guesses; exhibit which com- 
 pounds are incompatible, unless one of the com- 
 ponents is in the minimum; by well-determined results 
 (explaining the refractory nature of each at a 
 certain temperature, in the different ranges or rings, 
 afforded by the potter's oven) supply means for com- 
 paring and verifying isolated or fresh productions, as 
 well as the varieties of the series ; arrange the species 
 in that order in the scale of excellence to which each 
 is indisputably entitled ; distinguish their essential 
 and mutual relations which determine their agree- 
 ment; regard as of one species all those kinds 
 which have common characteristics of quality and 
 components ; and, by its processes and determined 
 calculations being restricted by scientific principles 
 and mathematical precision, supply the best possible 
 chance to improve the productions of Britain to the 
 perfection and excellence of Nankin porcelain. 
 
 Results thus contemplated are no longer pro- 
 blematical ; however, in bygone times they might 
 reasonably have been questioned, when the Manu- 
 facture was but a traditional practice, and its fabrics 
 coarse and mere blunges of the ingredients ; when all 
 the stoneware had a compact texture, and split on 
 sudden rise of temperature ; when the porcelain was 
 incapable of bearing, without cracking, alternations 
 of heat and cold ; before Cook worthy had supplied 
 the conception of a durable common porcelain, though 
 his success scarcely experienced the encouragement 
 he merited ; or, were known the properties of steatite 
 and magnesia to prevent or preclude fusion, yet not 
 impart any colouring principle ; or, those of barytes 
 
422 CHEMISTEY OF POTTERY. 
 
 to supply the place of saline fluxes ; or, those of 
 pumice-stone to resist any solvent of the varnish ; 
 or, the common porcelains of Champion and Turner 
 had been proved refractory in the oven ; or, the 
 analysis of felspar had instructed us, from very 
 common materials to compose it artificially ; or, the 
 productions of Spode had been investigated and 
 recognised as a real porcelain. 
 
 The researches of chemistry are authorities for 
 regarding the elements silica, alumine, and alkali in 
 the following relations : the first, as most efficiently 
 acidulant ; by (electro-negative or) recipient potency, 
 and its insinuative momenta, in various multiples 
 of 4 it combines, and whatever other acid may 
 be present, remains in combination with bases, in 
 every mineral, to the highest (or electro-positive) 
 active element, the alkali ; the next, alumine, as 
 neutral and convertible, receptive of many multiples 
 of 4 of either or both of the others, with the former of 
 which it more frequently and readily combines than 
 with any other element ; when mixed in water and 
 left to evaporate, the atmosphere fails to separate 
 them ; yet when together alone, the most ardent tem- 
 perature is not productive of vitrescence, the silica is 
 devoid of adhesive potency, and at the temperature of 
 the cream-colour biscuit baking, 40 Wedgwood, 4717 
 Fahrenheit, water remains present with the alumine. 
 And the third, the alkali, by its peculiar supply of 
 oxygen in raised temperatures, as a flux promotes the 
 formation of all into a compact vitreous compound. 
 This effect causes the first to be named by some 
 writers the mtriftable earth ; also, because although it 
 
SCIENCE OF MIXING. 423 
 
 readily combines with iron, its great difference from 
 the substances named metal* renders very difficult its 
 assimilation. 
 
 Problem. When held in solution by an aciduline or alkaline 
 menstruum, are there any or what reciprocal combinative poten- 
 cies between alumine and the other earths, magnesia, lime, 
 barytes, and silica? 
 
 To solve this, the anhydrous earths used were 
 prepared with every care to preclude the presence of 
 acid or alkali, constantly remembering, that on mix- 
 ing two solutions of compounds, their respective com- 
 municative potencies solicit those relatively receptive 
 or quiescent (probably in other compounds agents, 
 not patients as herein), and in the precise degrees 
 of relative potency combine into two fresh distinct 
 and separate compounds, possessing communicative 
 potency to solicit further another proportion of the 
 receptive elements and form a different compound. 
 The great care and attention with which I endea- 
 voured to obtain correct results, frequently when all 
 my family were enjoying their midnight slumbers, 
 and the agreement between them and those of cele- 
 brated analysts, induce the opinion that they approach 
 as near to absolute truth as can be obtained from cur- 
 rent knowledge of processes. I therefore with more 
 confidence publish the results. In each experiment 
 saturated solutions of the substances were filtered 
 twice, and by evaporation concentrated to the specific 
 gravity which had the ratio of the atomic weight. 
 
 The combinative potencies of alumine and of 
 silica are great and equal ; that of alumine exceeds 
 that of magnesia, yet both are stronger than those 
 
424 CHEMISTRY OF POTTERY. 
 
 just mentioned ; and those of alumine and of lime 
 are comparatively weak. 
 
 The modus operandi of alumine soliciting silica 
 to combination may be inferred. All minerals in 
 which much silica is present, and only little alumine, 
 on being completely fused with potash, then reduced 
 to comminution and dissolved in muriatic acid, and 
 afterwards treated with plenty of pure water, by a 
 light flocculence insoluble in acids, indicate that silica 
 had been present in the aciduline solution. But 
 corresponding results are not presented on similar 
 treatment of minerals whose components are much 
 alumine and little silica. Fusion with potash equalises 
 the tenuity of the particles of a mineral, and the 
 mechanical separation of the silica present must be 
 proportionate ; but no experiment supplied results 
 like those of the presence of alumine, as to efficient 
 promotion of the chemical solution of the silica. 
 Therefore, the solubility is determined by the pro- 
 portions of the alumine. 
 
 In reference to alumine soliciting magnesia, cur- 
 rent knowledge is only paucile. The potency is 
 such that on being exhibited to the latter in any 
 solution combination ensues, together they precipi- 
 tate, and leave the menstruum again unappropriated ; 
 even the potency of potash on the former fails of 
 its effects when the two earths have a determined 
 relative proportion. 
 
 Process. A solution of muriate of magnesia alkalinise with 
 -test 2 there will be a trifling precipitate of ammoniacal muriate 
 of magnesia. Mix solutions of muriate of magnesia and muriate 
 of alumine in excess, then alkalinise with test 2 all will pre- 
 jcipitate, except the muriate of the test. Filter out, wash, and 
 
SCIENCE OF MIXING. 425 
 
 evaporate dry the precipitate ; next dissolve it in test 26, with 
 test 1 alkalinise, and raise the temperature to 220 Fahrenheit, by 
 which part of the alumine will be appropriated. The remainder 
 filter out, wash again, and evaporate dry, and dissolve in test 26 ; 
 the solution alkalinise with test 3, and the alumine precipitates, and 
 must be filtered out, washed well, and dried as already directed. 
 The process of boiling in potash, and precipitating by carbonic 
 -acid, repeat until all of both earths is obtained. 
 
 That alumine promotes the solubility of lime in 
 potash is inferred from these facts : when lime alone 
 is boiled in test 1, only a like quantity is appropriated 
 to what would have been by an equal quantity of cold 
 water without any potash ; and the solvent power of 
 the pure cold water is much greater on lime when 
 alumine and potash are added and the temperature 
 raised to 218 Fahrenheit. 
 
 In employing the potash as stated, considerable 
 care was necessary to preclude the possible effect of 
 the carbonic acid on the alkali itself as well as, the 
 precipitate. There was no precipitate obtained from 
 mixing a solution of muriate of lime with one of mu- 
 riate of alumine, or magnesia, or barytes, or strontia ; 
 neither from mixing one of muriate of magnesia with 
 one of muriate of alumine, or barytes, or strontia ; nor 
 of muriate of alumine with muriate of barytes or of 
 .strontia ; nor of muriate of barytes with muriate of 
 strontia ; nor of lime-water and barytes-water. But 
 on mixing potash solutions of alumine and of silica, 
 after 48 hours' repose a copious precipitate resulted ; 
 also, on mixing a solution of silica in potash, with 
 lime-water, barytes-water and strontia-water. 
 
 The momenta with which the earths appropriate 
 moisture from the atmosphere have been determined 
 by Sir J. Leslie as silica 40, alumine 84, pipe-clay 
 
426 CHEMISTRY OF POTTERY. 
 
 85, felspar 80, carbonate of magnesia 75, carbonate^ 
 of lime 70, carbonate of barytes 32, baked clay 35, 
 red-hot clay (cooled) 8. Of their retentive potency 
 less is known ; although, as already stated, at a 
 temperature which fuses pure silver, 4717 Fahren- 
 heit, alumine retains a portion of moisture ; and 
 when all is vapourised, and the element left pure, 
 the loss is ascertained as 46 per cent. 
 
 The fact has been long known, that whenever three 
 of the earths are present together, either partial or 
 complete vitrescence ensues at 130 to 150 Wedg- 
 wood. Guy ton states that he obtained a temperature 
 which Saussure calculated equal to 1575 of this 
 pyrometer [without mentioning his data for com- 
 parison], by a stream of oxygen gas on burning char- 
 coal, and converted alumine into a white enamel, 
 semi-transparent and extremely hard, so as to scin- 
 tillate in collision with steel. 
 
 At a temperature equal to 150 Wedgwood the 
 mentioned results were obtained : magnesia and alu- 
 mine remained indifferent to each other's presence ; 
 alumine 1 + lime 2 remained a powder; A 1 + L 3 not 
 fused ; but these proportions, L 1 + A 2, L 1 + A 3, 
 L 1 + A 4, were fused by the temperature which 
 Ehrman obtained, by directing a stream of oxygen 
 over burning charcoal. Silica 4 + barytes 1 gave a 
 mass white and brittle ; S 3 + B 1 brittle and hard ; 
 S 2 + B 1 porous porcelain ; S 1 + B 1 not fused, 
 yet hard ; & 1 + 4 B intermediate between porcelain 
 and enamel ; S 1 + 3 B porous porcelain ; S 1 + B 2 
 greenish-white porous porcelain ; S 1 + B 1 a white 
 hard scintillating mass, intermediate between porce- 
 lain and enamel. At 156 L 4 + 8 1 powder^ 
 
SCIENCE OF MIXING. 427 
 
 L 1 -h S 4 brittle, not melted. Achard is of opinion 
 that for the compound to be verifiable, the earths 
 must have the mean proportions, alumine 1, mag- 
 nesia 2, lime 3 ; but when there is plus of magnesia, 
 the temperature must be 166 Wedgwood. Kirwan 
 is of opinion, that these proportions, A 3, L 2, M 1, 
 also A 3, L 1, M 2, and A 3, L 2, M 2, form 
 porcelains ; while A 3, L 1, M 3, and A 3, L 2, M 3, 
 form porous porcelains. 
 
 The imperfect knowledge possessed by persons 
 who could give such guesses is to be regretted, for 
 they are authorities on some important properties of 
 substances. The earths under certain conditions of 
 temperature, and the elastic pressure of the general 
 atmosphere, have essential and reciprocal potencies, 
 with definite momenta to solicit each other to com- 
 bination, rendering fixed or concrete immutable num- 
 bers of the atoms of ultimate components ; and hence 
 ever invariable in each artificial or proximate com- 
 pound, chemical, not merely mechanical. Analysis 
 with tolerable confidence determines the precise num- 
 ber of atoms of each ultimate component present ; 
 but because current processes of synthesis fail to 
 supply accurate and complete imitations, we remain 
 unacquainted with the real cause of their combination 
 in the proximate compounds. And yet none will ques- 
 tion that immense sums to the Manufacturer would 
 have been saved by the scientific solution of the pro- 
 blem, taking into the account the properties of the 
 several materials, and the necessity of reciprocal 
 action and quiescence during the manipulations and 
 process of baking, what determined quantities of 
 each will chemically effect the grand purposes of 
 
428 CHEMISTRY OF POTTERY. 
 
 which combination is susceptible, the acme of perfec- 
 tion, a durable, excellent and beautiful ware, adapted 
 for general utility. At present we are uncertain 
 whether this combination is, or not, consequent on a 
 principal component being infusible and insoluble ; or, 
 on temperature increasing the momenta of the com- 
 binative potencies of all, or of only certain of the com- 
 ponents of the silicic acid present with certain bases, 
 A ; and the metal, B, with the alkali of the glaze, D ; 
 or, of the silicic acid, A, and the alumine of the clay, 
 C, with the metal, B, and the alkali of the glaze, D ; 
 or, whether is their true combination, ABCD, AB + D, 
 ABC+ D, AC + BD, ABD + C, AD + BC, ACD +B. 
 The careful investigation and calculation, analytic- 
 ally, of the elements present in several of the recipes 
 according to which are compounded the wares 
 now fabricated, induce the following conclusions : 
 Assuming the numbers assigned to the combinative 
 potencies of the elementary atoms, p. 49,' I find the 
 composition of porcelain to be, in the mean, silica 2, 
 alumine 3, and lithia 0'667, or 16 x 2 + 24 x 3 + .8 = 
 112 ; likewise, that of the best flintware to be silica 
 1, alumine 4, or 16 + 24 x 4 = 112.* On the evi- 
 
 * Vauquelin regards somimte as silica 46 + alumine 49 ; and 
 euclase as silica 22 + alumine 35 ; and reasons thus, 49 : 3*2 
 : : 46 : 3 ; and 22 : 3-2 : : 35 : 5-09. But what have we in this 
 which we can regard as definite, 3 being the prime equivalent in 
 the former, and 5*09 in the latter? Now, regarding as I do the 
 combinative potency of silica as 4 x 4 = 16, and that of alumine 
 6 x 4 = 24, which reciprocally solicit each other, and likewise 
 the other elements, I am agreeably surprised to find in the 
 former the sommite 16 x 3 + 24 x 2 = 48 + 48, the ratio being 
 as 3 to 2 ; and in the latter, the euclase, 6x4 + 9x4 = 
 24 + 36 ; precisely as (16 + 8 = 24, and 24 + 12 = 36) 1 $ to 1 J. 
 
SCIENCE OF MIXING. 429 
 
 dence of numbers, then, and of such easy numbers, 
 we find an arithmetical solution of the problem of the 
 equivalence of combinative potencies for the wares 
 porcelain and earthenware ; a solution, to accomplish 
 which, the endeavours of a mighty genius, Reaumur, 
 were ineffectual, because not possessed of the facilities 
 we en joy ; a solution which is entitled to more attention 
 than it has yet received, and whose corroboration will 
 be by innumerable facts ; so that its verity, if not com- 
 pletely beyond all allegation of chance, has a proba- 
 bility of many millions to one, and every repetition 
 becomes a further power of the series, and a closer 
 approach to absolute certainty. The coincidence and 
 harmony of the numbers are the more remarkable, 
 because the effect of mere accident in the choice and 
 manner of persons making their arrangements ; yet as 
 far as indirect evidence can, they prove the possi- 
 bility of the substances being very much similar in 
 
 Guy ton tells us he " made, without kaolin, a biscuit having 
 the hardness, semi-transparency, and grain of porcelain, by giving 
 the proper degree of baking to a paste composed of 50 silica, 20 
 alumine, 24 magnesia, and 6 lime. I need not say that it would be 
 very easy to employ the same proportions of silica and alumine, 
 by choosing a good clay, without having recourse to the decom- 
 position of alum for the earth." Mr. Billingsley, at the Nungarrow 
 Manufactory, from Lynn-sand, potash, and other components, 
 made a porcelain which as an artificial felspar has some excellence, 
 and approaches nearest real felspar ; the expense certainly was 
 great ; and only was his ware defective through his being unac- 
 quainted with the principles of combinative potency. This was a 
 notable instance, how much the mechanical processes of pottery 
 are in advance of the " work and labour of love " for public benefit 
 the science of chemistry, in regard to atoms. Of the compo- 
 nents of the porcelain made at Lowestoft, prior to 1750, and also 
 of that at Bristol, in 1800, I have failed to obtain information. 
 
430 CHEMISTRY OF POTTERY. 
 
 elementary proportions, yet different in requisite 
 excellencies; while the best can be decided only by 
 investigations originated by other considerations.* 
 
 * A perfect porcelain body and glaze can be obtained by pro- 
 perly baking the natural kaolin and petuntse, whose proportions 
 are as previously stated, silica 64, alumine 24, alkali 12, or 60, 24, 16. 
 Agreeably to this standard, we can compare all bodies ; and, having 
 their quantities stated, we readily ascertain their approximation 
 to Nature. The mean of eight recipes for flintware is, blue clay 
 25, black do. 22, brown do. 18, China do. 16, flint 16 ; i.e., silica 
 6372 -f- 16 ; alumine 3223 -=- 24 ; lime 8 ; iron 132*5 ; which (re- 
 jecting the spice of lime and iron) show 991 doses of silica, and 
 1341 doses of alumine ; or rather less than one-eighth above the 
 mean 112 in 85. The mean of five soft porcelain recipes is, blue 
 clay 20, China do. 40, grauen 28, flint 12 ; i.e., silica 7204 4- 16, 
 alumine 3071 -=- 24 ; lime 13 ; iron 55*25 ; or one half-dose above 
 112 doses of silica, and one twenty-fourth of a dose short of 128 
 doses of alumine ; only one-twentieth of an unit short of the mean 
 112 in 83. The mean of other five Bone China recipes is, blue 
 clay 99, C. clay 321, grauen 315, bone-earth 354, flint 42 ; i.e., 
 silica 55731 + 16, alumine 17487 -=- 24, alkali 473 -i- 8, lime 
 396 ; or two-thirds of a dose above 870 doses of silica, nine 
 twenty -fourths of an unit short of 728 doses of alumine, and a mere 
 trifle short of 60 doses of alkali, besides the potency of the lime, 
 32. There is one twenty-eighth excess above the mean of '112, in 
 661 ; I think there needs scarce mention, that these will be soft, 
 fragile, and readily. affected by sudden rise of temperature. The 
 two recipes for porcelain, and the three for flintware, published by 
 Mr. Lakin, have respectively, silica 24056, 45130, alumine 7024, 
 13850, alkali 1064, 3860, lime 384, 420 ; and silica 54300, 45800, 
 45300, alumine 20000, 16200 (the latter spiced with alkali from 
 the grauen). They contain doses of silica, 376, 705, alumine 
 293, 577, alkali 133, 482; lime 12, 13; also, silica 848^, 715;!, 
 708, alumine 8331, 675, 675 ; and vary from the mean of 112, 
 five parts of an unit minus in 290, } plus in 564, ^ plus in 663, 
 T 8 ^ plus in 553, and J minus in 549. Several hard porcelain 
 recipes give the mean, kaolin (green) felspar 35, C. clay 20, blue 
 
f- 
 SCIENCE OF ^MIXING. 431 
 
 To the preparation of the clays, as a chemical 
 process, great attention is indispensable, as well as to 
 their intermixture with flint and the other compo- 
 nents ; for, although their causes are like those which 
 produce other compounds, the effects are not pre- 
 cisely similar ; for thereon depend the composition, 
 aggregation, and texture of the wares, as proved by 
 the fracture. While pursuing certain processes, 
 
 do. 15, cracking do. 10, brown do. 10, black do. 10; i.e., silica 
 6000, alumine 3345, alkali 600, iron 122-5, three-fourths of a dose 
 above 93 doses of silica, one-sixth of a dose above 139 doses of 
 alumine, and 75 doses of alkali ; and there is an approximation of 
 yV plus in 88 to the general mean of 112. Moderately good ware 
 was fabricated by Kivers and Clowes, Shelton, in 1820, from blue 
 clay 697, brown and cracking 230, C. clay 174, flint 579; i.e., 
 silica 1395J.8 and alumine 37443, a small fraction of an unit 
 short of 2178 doses of silica, and 1560 of alumine, being 32 + to 
 22, instead of 32 to 24 ; yet the mean 112 is precise in 158. The 
 relative quantities of the components of Champion's porcelain, 
 fabricated at New Hall, Shelton, were stated as ball clay 1|, C. clay 
 8, C. stone 10, bone-earth 16, ground with a frit of soda 1, C. 
 stone 4. The alkali promoted the semi-fusion and translucence ; 
 and the elements being 1638, and 428, almost 16 to 4, a sixth of 
 a unit minus the mean of 112 in 18. The rationale proves that 
 the compound approximated the nearest to perfect porcelain of 
 any at that day manufactured in Britain. 
 
 In this way readily is determined the probability of excellence 
 in the results of combinations ; and more so, could we ascertain 
 the precise weight of each component in two distinct bodies, also 
 their relative proportions and specific gravities after sustaining the 
 same high temperature ; and of similar substances subjected to 
 other temperatures, and by difference of specific gravity, indicate ; 
 variation of products, suggest the cause and the efficient remedy ; 
 and apportion the components in the ratio of specific gravity ; 
 and other compounds be determined, either the specific gravity 
 from the proportions of the components, or these from the other. 
 
432 CHEMISTKY OF POTTERY. 
 
 frequently do improvements suggest themselves, use- 
 ful, because extending the practical results. That 
 one kind of clay more readily mixes with water and 
 appropriates more silicic acid from the flint than 
 another, and therefore requires a different height of 
 temperature for baking the biscuit, which is seldom 
 accurately determined, has been long known, to the 
 slip-makers especially. But the materials may not 
 always be in the same state of composition in Nature, 
 and their employment will cause difference in the 
 biscuit. For the practice to be so tenaciously con- 
 tinued, of trusting for the quality of w T ares to the 
 vague and uncertain proportions of watery mixtures 
 of clays, and of flint, etc., by mere measure, and omit- 
 ting their relative density prior to lawning into the 
 slip-tub and kiln, argues disregard of the certainty 
 of scientific pottery. 
 
 The recipient potency of the alumine present in 
 the natural clays solicits moisture with great momen- 
 tum from each substance in contact in which it is 
 present, even to the amount of 20 per cent. ; hence on 
 applying clay to the tongue, it quickly adheres. This 
 appropriation of moisture is especially advantageous 
 to the material, by causing a gradual disintegration 
 of the mass during exposure to the alternations of the 
 seasons, either at the wharfs, or on the Manufactory. 
 The Manufacturer who has adequate capital finds his 
 advantage in keeping a large stock, that it may be 
 well-weathered ; and in his vaults a sufficient quan- 
 tity of clay ready for the workman ; as there, after the 
 heat of the slip-kiln has mechanically connected the 
 particles of the plastic mass, the longer it remains the 
 more important are the changes effected spontaneously 
 
SCIENCE OF MIXING. 433 
 
 by the chemical potencies of the components. I have 
 heard it several times mentioned, that the Jasper and 
 other dry bodies made by Messrs. Wedgwood are pre- 
 pared several months prior to being used. I am not 
 able, clearly and with confidence, to determine whether 
 the green state of the ware, after certain manipulations 
 is, or not, really an invisible chemical process, because 
 of the presence of water and vegetable particles 
 (similar to decomposition of vegetable mashes by fer- 
 mentation), in which are active and quiescent alike, 
 silicic acid, alumine and alkaline earths. The earths 
 fresh supplied from the mines form clay, of which the 
 ware fabricated is defective, cracks, rifts while in 
 progress, and decomposes afterwards. While the 
 earths long exposed to the atmospheric changes, 
 more disintegrated, readily mix with the water, pass 
 through the lawns, form clays which the workman 
 can use to his satisfaction, and the reflecting Manu- 
 facturer thus is led to cause only long- weathered 
 earths to be formed into clays kept as long in the 
 vault as is convenient for his capital, instead of in- 
 curring the sacrifices consequent on the articles being 
 fabricated from clays taken into the work-room 
 reeking-hot from the slip-kiln. 
 
 The fabrication of good ware requires careful 
 selection of the earths for the body, to provide for 
 and ensure exact coincidence of pyrometrical expan- 
 sion by heat, between the biscuit and its vitrescent 
 coating or glaze. By combustibles prevented from 
 injuring the properties of the components, the baking 
 must be at a temperature proper for those of the 
 glaze to reciprocally solicit and be solicited by 
 
 those of the surface of the biscuit in contact. The 
 
 2 F 
 
434 CHEMISTRY OF POTTERY. 
 
 purity of the components of the biscuit, the extreme 
 comminution of those of the glaze, and the precise 
 temperature to ensure their chemical combination, 
 are essential conditions of the science of potting. 
 
 When there is excess of silica (called orer-flhtt- 
 ing), the deficiency of alumine leaves unappropriated 
 that excess ; and the pyrometrical expansibility dif- 
 fering in different parts of the same vessel, rifting 
 ensues, or when the excess regularly pervades all the 
 vessel, it precludes the proper adhesion of the glaze 
 particles, and after the baking the surface is left dry 
 and rough, similar to what is the state of ware on 
 which the workman has applied the sponge too 
 frequently and injudiciously to the surface. A like 
 effect results when excess of lime is present. When 
 there is deficiency of silica (under-flmtmg\ the quan- 
 tity of moisture present with the alumine, on being 
 evaporated cleaves the vessel, or causes cracking. The 
 silicic acid of the grauen also frequently appropriates 
 alkali from substances with which it is baking, and 
 leaves dull and rough what otherwise would have a 
 fine velvet gloss. 
 
 While obeying certain laws agreeably to the 
 dimensions of the articles, the great difference of 
 component materials causes variation in the pyrometri- 
 cal expansibility of bodies, which at varied degrees 
 of raised temperature become not merely mechanic- 
 ally solidified, but chemically less susceptible of 
 solicitation from acid or alkali. The surfaces appro- 
 priate or dissipate heat, and in proportion to their 
 bulk retain it ; and the mutability of temperature 
 depends on the ratio the solid contents bear to the 
 surfaces ; the more extended these in proportion to 
 
SCIENCE OF MIXING. 435 
 
 the bulk, the quicker will be the pyrometrical altera- 
 tion ; as the temperature of the surrounding medium 
 will be less efficient, the greater the bulk is in pro- 
 portion to the surfaces. The flat and long articles 
 have more extended surface in proportion to the 
 solidity, and vice versa ; in vessels of like figure their 
 surfaces are as the squares, and their solid contents 
 as the cubes of their diameters. In vessels of like 
 shape and substance but different sizes, the capacity 
 for heat is as the cubes, and the mutability of 
 temperature as the squares of their diameters. 
 
 Bodies brittle, or devoid of flexibility, crack by 
 sudden heat, because the unequal action of the par- 
 ticles in fixation of oxygen varies the expansion of 
 the orbital spaces of their atoms ; and this variation 
 creating opposition among them, the substance 
 separates, and the manner is distinguished by the 
 terms, crack, rend, rift, flee, break / and a like result 
 ensues whenever a body, whose particles are much 
 separated by that expansion, is subjected to sudden 
 great diminution of temperature. Very thin vessels, 
 therefore, best bear these changes. Current know- 
 ledge fails to determine what arrangement of particles 
 is the real cause of brittleness. Many a body which 
 bears a very high temperature by sudden cooling 
 becomes hard and brittle (as steel and glass), and 
 often very inconveniently when they are required to 
 be soft and flexible, and which latter can be secured 
 only by annealing, or gradually and carefully cooling 
 them in a period of time proportioned to their bulk 
 and solid contents. The sudden contractile property 
 of most metals is counteracted by their flexibility ; 
 
 but although exceeding these in flexibility and 
 
 2 F 2 
 
436 CHEMISTRY OF POTTERY. 
 
 elasticity, glass is so peculiarly brittle, that to expand 
 or contract with temperature applied annealing is 
 indispensable.* 
 
 The potters of Bow and Chelsea, from com- 
 pounding well-washed sand from Alum Bay, Isle 
 of Wight, ground cullet, and pipe-clay, fabricated 
 porcelain, which was covered with a glaze, chiefly 
 of lead, which had considerable demand in the early 
 part of the last century. The removal of the Chelsea 
 establishment in 1748 to Derby, was the cause of 
 alteration of the components, from which excellent 
 ware is now fabricated. Of like components, with a 
 little alkali, was formed the porcelain fabricated at 
 the Worcester establishment, formed in 1751, by the 
 enterprise of some of the clergy of that cathedral, 
 and for many years the principal director, *ub rosa, 
 was Dr. Davies. 
 
 The attempts of the Staffordshire Manufacturers, 
 about the same time, Littler, Yates, Baddeley, and 
 others, to fabricate porcelain, completely failed, 
 because of not understanding the chemical properties 
 of the materials employed. I do not feel warranted 
 in mentioning the information received of the pro- 
 portions they severally adopted. But it seems proper 
 to state, that their practice of forming the china 
 
 * The deficiency just mentioned would induce the supposition 
 that glass is analogous to steel. Articles of steel, suddenly cooled 
 from a high temperature, remain more expanded in surface than 
 when, from like temperature, carefully protected while brought 
 down to that of the atmosphere. Without the annealing process, 
 the particles forming the external surface, and which suddenly 
 cooled, would remain more contracted than those interior, and 
 not adapted to their development, as less slowly cooled. 
 
SCIENCE OF MIXING. 437 
 
 body of a frit, was suggested by the usual methods 
 of the glass-makers, to prepare the materials for their 
 glass pots, by rendering them opaque, yet not homo- 
 geneous, of strong adhesion as a semi-vitrescent 
 paste ; the chemical combination of the silica, alu- 
 mine, alkali, and metallic oxides being commenced, 
 the carbonic acid and moisture being dissipated from 
 the components, superseding their swelling when in 
 the vessels. 
 
 The formation of porcelain results from the 
 proximate chemical combination, by very high tem- 
 perature, of an alkali with silica, alumine, and lime, 
 in like proportions to those which Nature combines in 
 certain species of felspar. The earths are rendered 
 more refractory by their state of purity ; and the 
 basis is a clay which bakes very white, while the 
 other components promote incipient vitrification, 
 forming a compound intermediate between flint 
 ware and glass, yet infusible by the high tempera- 
 ture which renders the texture fine but compact, the 
 fracture semi -vitreous, with translucence, a peculiar 
 toughness, and perfect white tint after each subse- 
 quent baking. 
 
 The circumstance of only the felspar of Limoges 
 being employed as the chief component of the Sevres 
 porcelain, suggested the search for a similar mineral 
 in Britain ; and in 1818, James Ryan, F.S.A., dis- 
 covered it in the useless refuse of a discontinued lead 
 mine at Middletown Hill, just entering Wales, from 
 Salop. By employing the greenish or slate-grey fel- 
 spar (which I distinguish by the name kaolin) as a 
 component of the body, and the brown lemon, 
 petuntse, the more fusible because of the presence of 
 two additional doses of alkali, as chief component of 
 
438 CHEMISTRY OF POTTERY. 
 
 the glaze, British porcelain, from its state of in- 
 feriority to those of the European continent, enjoys 
 a new and important era, and excellence and supe- 
 riority over any other, rapidly approximating to 
 perfection the ne plm ultra of the Art which pro- 
 bably will result from the increasing researches and 
 extended views of mineralogists and chemists in the 
 present century. 
 
 In forming the best hard porcelain, part of the 
 components of both body and glaze are formed into 
 frits, and then with the other components, earths, 
 and alkali, and oxide, ground very comminute prior 
 to being evaporated on the slip-kiln, or used in the 
 dipping-tub ; the finer the grinding, the more beau- 
 tiful will be the ware. The biscuit is translucent, 
 much like well-ground glass ; in very thick plates 
 (two or three lines), there is merely a shade, free 
 from a brown or muddy tint, while in others very 
 thin there is a distinct but colourless figure. I need 
 scarcely mention that the proportions of the compo- 
 nents in both are carefully determined. In using 
 the minimum of kaolin, translucence is obtained only 
 by extremely high temperature, that would affect the 
 shapes of the articles was the maximum employed.* 
 
 *The progression towards perfection, in the transatlantic pro- 
 ductions, is very rapid, according to Professor Silliman : " The 
 porcelain of the Philadelphia Manufactory is very beautiful in all 
 the principal particulars ; in symmetry of modelling, in purity of 
 whiteness, in the characteristic translucence, in smoothness and 
 lustre, and in the delicacy and richness of the gilding, and of the 
 enamel painting. That it rivals the finest productions of Sevres 
 itself, it is not necessary to assert ; but it certainly gives every 
 assurance, that if properly supported, it will not fail to meet every 
 demand of utility and taste, which this great and growing country 
 may present. 
 
SCIENCE OF MIXING. 439 
 
 Occasionally this last effect is counteracted, and the 
 contractile property equalised, by using steatite or 
 soap-rock, fusible readily with silica and alumine, 
 partially with either, but not at all used alone. 
 Because of the failure of some establishments which 
 commenced the Manufacture of hard porcelain, an 
 opinion has been current that it cannot compete with 
 that of the soft, though the proofs of its rivalry are 
 obvious in the increasing prosperity of some other 
 establishments. 
 
 As in all reasoning we must proceed from what 
 is known or determined to what is unknown or re- 
 quired ; there is indispensable in each proposition one 
 subject whose determined potency adapts it for a 
 standard of the calculations. Throughout the whole, 
 silica has been regarded as possessing this readily- 
 determined potency. The reduction of artificial 
 silicates to their equivalent components was an im- 
 portant problem, that might have remained probably 
 a long time without solution, had not circumstances 
 of a peculiar kind led me to consider its importance. 
 With the numeral 4 as the index of combinative 
 potency, I have been enabled, with considerable 
 accuracy, to determine the equivalent ratios of many 
 compounds ; and I may here assure the reader, that 
 on the same principle, with the aid of the Tables in 
 Part III., he will himself readily accomplish the 
 determination of the components of any compound 
 he chooses to fabricate. And the respective pro- 
 perties of the ingredients will be more clearly 
 comprehended from the results. 
 
 It is proper to remark, that I am persuaded 
 when chemical researches have been more steadily 
 
440 CHEMISTRY OF POTTERY. 
 
 pursued in reference to this interesting Manufacture, 
 so that the accuracy of reasoning on the combinative 
 potencies of the elements distinctively can be with 
 confidence employed with reference to the artificial 
 compounds, we shall find that the respective in- 
 gredients do not reciprocally combine in an indefinite 
 degree, or by imperceptible gradations, but that they 
 proceed, per xaltem, regularly, in definite proportions 
 with reference to being multiples of the first potency, 
 and that uniformity exists in the resulting com- 
 pounds only when there is precise correspondence 
 in the proportions. This view is a rational sequence 
 of the principle that combinative potency in every 
 instance may be modified by a second or third 
 multiple of one of the components, as well as by 
 raised temperature, and other adventitious con- 
 ditions of the compound. 
 
 There remains little likelihood of the Art ever 
 again supplying a possessor of the imperial purple, as 
 in the instance of Agathocles ; but it can boast an 
 incomparably greater number, than can crowns or 
 coronets, of honest men, " the noblest work of God : " 
 
 Among the ancient royal names 
 
 Agathocles I gladly find ; 
 Pre-eminence he chiefly claims, 
 
 For virtues of the noblest kind ; 
 To deck his board with bowls of gold 
 
 The usage of the times required ; 
 But he, his father's earthen mould 
 
 With filial fondness most admired ; 
 'The Potter's vessels there had place, 
 And with the gold the tables grace. 
 
 TESTI, the Italian Horace. 
 
[ 441 ] 
 
 CHAPTER III. 
 
 BODIES. 
 
 IN this Manufacture the word BODY signifies 
 the plastic compound of materials, in the moist state 
 named Clay, because then workable ; and also in 
 contradistinction to the fusible covering or Glaze. 
 The combination of the materials, however, differs 
 with almost every Manufacturer, who seeks to distin- 
 guish his ware by some supposed or real excellence. 
 
 On the principle promulgated by that persever- 
 ing and intelligent chemist, Guyton Morveau, only 
 Stone Ware and Porcelain are entitled to the name 
 POTTERY. And he further indulged the opinion, 
 that the public health will be best consulted by sub- 
 stituting a supply of porcelain in the place of com- 
 mon earthenware, and such as is required to bear 
 the fire, delft and flintware, in reference to economy, 
 neatness, wholesomeness and durability. 
 
 Such an entire change of system, however, is 
 superseded by scientific potting, which regards the 
 reciprocal potencies of the materials, and always 
 finds, in compounding several together, their equiva- 
 lent numbers, or multiples thereof, are present when- 
 
442 CHEMISTRY OF POTTEEY. 
 
 ever they chemically combine, not mechanically mix ; 
 and consequently that the sum of the equivalents 
 will denote the proportions of combinative potencies. 
 
 Problem. It is required to combine a body, either opaque or 
 translucent when baked, which shall be so compact, and durable, 
 and receptive of the particles of glaze and colours, as never again 
 to' separate (craze) by action of other substances, or change of 
 temperature. 
 
 The Common Red Ware is formed of materials 
 prepared by a method practised prior to any historical 
 records. A small tank is formed, about two or three 
 feet square and deep, at the corner of a second, in 
 size in accordance with the conveniences supplied by 
 the spot. The bottom of the larger has fine sand 
 strewed over it in a thin stratum, and after the clay 
 has been violently agitated in the smaller tank, in 
 water, to loosen and allow to subside portions of 
 gravel or pyrites present, the mixture is passed 
 through a hair-sieve upon the larger, till there is a 
 covering of about four inches, when the mass is left 
 to be evaporated by the atmosphere ; and hence the 
 tank is named the Sun Pan. Over this stratum a 
 succession of others is formed, till the whole is more 
 than a foot thick of clay, and then it is removed and 
 slapped for use. The biscuit state of this ware, 
 because baked only slightly, and just to sustain the 
 transition from heat to cold, is very porous. The 
 presence of oxide of iron, also of the components of 
 the coating or glaze sulphite of lead,* and oxides 
 
 * The fact is lamentable, though scarcely noticed, that in fabri- 
 cating some of the vessels for domestic purposes, materials are 
 employed which are extremely deleterious. Lead and its oxides 
 
BODIES. 443 
 
 of manganese and copper or iron prevents its being 
 sufficiently refractory to sustain a high temperature, 
 and its glaze is therefore very fusible. 
 
 admitted into the stomach in very minute particles and quanti- 
 ties injure the important blessing, health, of our fellow-men; 
 gradually affecting the organs of digestion, there is insensible 
 operation of the poison, with consequent emaciation, cholic, con- 
 vulsions and diarrhoea. The men who dip common ware often 
 have most of the systems of the Painter's Cholic progressing 
 from dry belly-ache, eructations, slight nausea, thirst, anxiety, 
 quick pulse, obstinate costiveness, vomiting of acrid bile, shooting 
 pains from the navel to each side, spasms in the intestines, the 
 belly highly painful when touched, and the extremities tending 
 to paralysis. Even when these do not terminate fatally, too 
 frequently they cause palsy, contractions of the hands and feet, 
 inability of the muscles to perform their office, and in this miser- 
 able state the patient lingers out many years. Those who use 
 such wares thus become the victims of their own ignorance, and 
 of the imprudent avarice of the Manufacturer, who should under- 
 stand that, while he never ought to be either the dupe of cupidity 
 [or the victim of ignorance], it is no innocent matter to the trade, 
 as well as society, for any productions to prove valueless; the 
 stigma affects the worth of all ware ; neither should he, for economy 
 merely employ in body or glaze, or both, materials which more 
 readily bake ; for ultimately he would be benefited, were all vended 
 wares to possess certain relative perfection and excellence. When 
 the baking merely agglutinates the glaze to the body, the whole of 
 it may be divided and appropriated by the liquids, aciduline or 
 alkaline, which come into contact ; even very hot water has almost 
 equal effect ; the crazing process commences ; the ware, whatever 
 its appearance, speedily fails in using, because not being properly 
 baked, the fabric is readily destructible by rough usage. The dif- 
 ference in the pyrometrical expansibility of body and glaze cause 
 the latter to separate minutely, not by the naked eye perceptible 
 when new, but plainly so when washed after containing hot, greasy 
 liquids. The danger to the public health, from employing such 
 defective fabrications, is equally imminent, although insidious and 
 concealed. 
 
444 CHEMISTRY OF POTTERY. 
 
 The Delft Ware, so named from the town in Hol- 
 land where it continues to be made (and frequently 
 applied to what the Manufacturers call Cream Colour), 
 on its introduction was a grand invention, because 
 of the beauty of its glaze ; and it is kno\yn to have 
 suggested the Staffordshire White Stone Ware, from 
 which there was an easy transition to Flint Ware. 
 The Delft body is a compound of natural clays, as no 
 one alone possesses the properties indispensable to the 
 fabrication of suitable ware. The workman regards all 
 clays with excess of alumine as too fat, because vessels 
 fabricated thereof, whatever their substance, would 
 require a long time to dry for baking, fail in their 
 shape by sinking down, and crack by the evaporation 
 of the moisture present ; and that as too poor in 
 which is excess of silica, or sand, or marie, and which 
 therefore will not retain the shape given by the ope- 
 ratives. To diminish this fatness without affecting 
 the ductility proper for the manipulations, marie or 
 sand is carefully mixed, and its silicic acid is appro- 
 priated by the alumine, whose particles being thereby 
 kept asunder, the requisite evaporation proceeds with- 
 out the vessel sustaining injury by sinking or crack- 
 ing. Delft ware, consequently, is defective ; it is 
 baked slightly, and only sufficient to preclude sinking 
 from the temperature requisite to combine and vitrify 
 the components of the glaze, which would be injured 
 by a higher temperature. With two or more clays are 
 mixed some sand, or marie, whose lime renders the 
 body compact from the semi-fusion with the glaze, 
 which on this ground has a white and glossy appear- 
 ance. Yet the biscuit and glaze suffer from sudden 
 alternations of temperature, and appropriate grease 
 
BODIES. 
 
 from hot greasy liquids, because of its soft nature, 
 composed of vitrified lead and silica, by tin rendered 
 white and opaque. M. Bosc d'Antic gives these 
 proportions for common : 46 lead calc, 6 tin calc, 
 40 fine sand, 8 sea-salt ; and for the best, 38, 10, 40 
 and 12 respectively. Pa jot de Charmes says that 
 Salt thrown into the oven while pottery is baking 
 forms a glaze, and that it improves the whiteness 
 and clearness of glass. Sulphate of soda will not 
 succeed with sand alone, but equal parts of sand, 
 carbonate of lime, and dried sulphate of soda, formed 
 a clear, solid, pale yellow glass. 
 
 PORCELAIN. Hard the finest and most valuable 
 has these essential and indispensable properties : 
 The component earths are combined in such relative 
 proportions, that proper baking renders the mass 
 translucent, firm, hard, dense, durable, and sonorous 
 when struck with a hard body ; a white colour ap- 
 proaching the tint of milk ; a grain fine and close ; tex- 
 ture compact, intermediate between the closeness of 
 glass and the obvious porosity of the best flint- ware ; 
 fracture semi-vitreous, and will sustain without in- 
 jury sudden alternations of high and low temperature ; 
 the presence of an alkaline component possessing the 
 quality of a flux relative to the others, most economic- 
 ally brings all of them into a state approximating to 
 fusion, and in the kinds varies the translucence ; 
 which foreigners try by every method to decrease, 
 and the English Manufacturers seek to increase, 
 while preserving the fine close grain. The biscuit 
 must be adapted to readily absorb water without 
 injury. This is covered with a glaze, clear, white, 
 transparent, indestructible by acids, or alkalies, or 
 
446 
 
 CHEMISTRY OF POTTERY. 
 
 temperature, beautifully fine, to the touch smooth, 
 and appearing soft like velvet, rather than lustrous 
 or glossy like satin. When first applied to the 
 ware, the water readily permeates the pores, and on 
 the surface the thin coating of components quickly 
 dries into a solid shell uniformly thick over all the 
 parts, and sufficiently firm to bear handling without 
 being rubbed off' during removal into the seggars. 
 
 Soft. The body is less dense, yet sonorous, white, 
 translucent, granular, and very fine porous fracture, 
 harder and less brittle than glass, moderately hard 
 glaze, and will sustain considerable alternations of 
 temperature. 
 
 The following comparison will probably supply 
 useful information, and gratify the curiosity of the 
 scientific chemist : 
 
 
 Staffordshire 
 
 Berlin 
 
 Vienna Sevres 
 
 Dresden Nankin 
 
 
 Hard 
 
 Soft 
 
 
 
 
 Silica 
 
 0-750 
 
 0-610 
 
 0-590 
 
 0-640 0-696 
 
 0-602 0-660 
 
 Alumine 
 
 0-096 
 
 0-250 
 
 0-340 
 
 0-250 0-250 
 
 0-320 0-180 
 
 Alkali 0-030 
 
 0-020 
 
 0-020 
 
 0-096 0-020 
 
 0-020 0-120 
 
 Lime 0-012 
 
 0-050 
 
 0-008 
 
 0-010 0-018 
 
 0-008 0-040 
 
 Magnesia 0-050 
 
 0-050 
 
 0-027 
 
 o-o o- 
 
 0-007 0- 
 
 Water 0-050 
 
 0-010 
 
 0-012 
 
 0010! 0-040 
 
 0-040 0- 
 
 
 0-988 
 
 0-990 
 
 0-997 
 
 1-000 | 0-998 
 
 1-000 1-000 
 
 Stone China, in imitation of the Oriental, is very 
 thick, strong, semi-translucent, vitrescent, coarse 
 texture, granular fracture, durable, but with a very 
 soft glaze ; and by the addition of a portion of slag 
 of the iron-smelting furnace, is formed the kind 
 called the Patent Ironstone China. 
 
 The Dresden Porcelain, equally refractory in 
 the baking as is the Japanese, which it excels in 
 
BODIES. 447 
 
 whiteness and sonorosity, according to the opinion of 
 the English connoisseurs, is firm and compact, and 
 will sustain without injury alternations of tempera- 
 ture ; and has a fracture not granular, but uniform 
 and semi-vitreous, similar to white enamel. Its 
 fusible components are the tarso, or felspar gravel, 
 from the River Po ; and its infusible is the clay from 
 Aue, near Sneeberg. This clay, by Rose's analysis, 
 has silica 52, alumine 47, iron 0'33. These certainly 
 are not chemically equivalent, but possibly some 
 error exists in the analysis ; however, the near coin- 
 cidence between the two numbers, thirteen fours and 
 twelve fours, and the proportions in other clays, is 
 calculated to cause the reflecting mind to regard the 
 principle of combination as more extensively applic- 
 able than was previously supposed. The materials 
 are combined in proportions, at present carefully con- 
 cealed. The fusibility of the felspar gravel promotes 
 the density and smooth peculiar lustre, while the clay 
 secures its firm solidity and beautiful white appear- 
 ance, and together there is regular contraction during 
 the baking process. Of the processes we only know 
 that the clay is prepared at the equinoxes, when 
 the rain-water used for levigating the earths and 
 mixing the body is of a certain temperature, and 
 conjectured to be less adulterated with tralatitious 
 ingredients. By keeping long the prepared clay 
 previous to its fabrication into ware, a kind of fer- 
 mentation ensues, which destroys any combustible 
 material present, and prevents discoloration of the 
 biscuit. The ware is baked with well-dried white 
 wood, whose alkali combines with that of the felspar 
 in forwarding the vitrification of the ware. 
 
448 CHEMISTRY OF POTTERY. 
 
 The Oriental porcelain is of three qualities ; viz.,. 
 BODY best, equal proportions of kaolin and petuntse^, 
 with a component kept secret ; second, kaolin 40, 
 petuntse 60 ; and common, kaolin 25, petuntse 75. 
 GLAZE 1, white petuntse 100 parts, sulphate of lime 
 calcined and pulverised 1 part mixed with 100 lime 
 rendered more alkaline and caustic by being three or 
 four times calcined with wood in a certain propor- 
 tion ; for 2, the like with additional sulphate of lime. 
 Then for best glaze, liquids of equal density are formed 
 of 1 and 2, and ten parts of the former are added to 
 one of the latter. The Clay is prepared by a laborious 
 method. In paved tanks or pits of several yards 
 dimensions, men tread together the component earths, 
 similar to the English practice of plasterers treading 
 hair-mortar, until the whole mass is tawed or kneaded 
 to a proper consistence, which is regarded as indis- 
 pensable to the fabrication of fine ware, as thereby 
 almost every particle of heterogeneous substance 
 present, whether by accident, or adulteration at the 
 quarries where the cakes are first formed, is dis- 
 covered and abstracted ; as it has been proved that 
 air-bubble, hair, or sand will spoil the vessel in which 
 it occurs. Portions of the well-tawed mass are then 
 manually rolled various ways on slabs to prepare 
 them for subsequent manipulations. For the Glaze,. 
 the powders of the petuntse and sulphate of lime, in 
 proportions above stated, are mixed in water, and, in 
 the technicality of the art, called an oil ; calcined 
 carbonate of lime is slaked by sprinkled water, and 
 the powder is strewed over fern, and thus again 
 burned, which latter process is repeated thrice for 
 the best glaze ; and to this is added 1 per cent, of the 
 
BODIES. 449 
 
 calcined sulphate ; the liquids are then mixed as 90 
 of the former to 10 of the latter. This additional 
 alkalinity not only adapts the glaze the more readily 
 to fuse, but also more efficiently to solicit to combi- 
 nation the surface of the ware with which it is in 
 contact. 
 
 The Sevres Porcelain excels all the others 
 manufactured in France, notwithstanding the great 
 improvement which has been made in them ; and the 
 fact that the trade can be followed by the sons of the 
 aristocracy, without derogation ; with all the other 
 properties of real hard porcelain, in compactness, etc.^ 
 as already stated, and a glaze, fine, colourless, and 
 transparent, its fracture has more the appearance of 
 very fine lump-sugar, than a vitrified durable sub- 
 stance. The Materials for both Body and Glaze are 
 the (Melting Spar) felspar and clay from St. Yrieux 
 la Perche, near Limoges, 400 miles from Paris, and 
 some from Alen^on, and from near Bayonne. They 
 are prepared for the Manufacturer (as in China) on the 
 spot where quarried ; and, being delivered in a state 
 ready for mixing together, a much less working capital 
 is required than for the purposes of the British Manu- 
 facturer. The two Recipes handed me by a friend who 
 had visited most of the French Manufactories give : 
 Body Felspar 67, Clay 33 ; and Clay 66, felspar 15 r 
 sulphate of lime 9, carbonate of lime 6 ; baked ware 
 in a comminute state, or semi-fluid 10; Glaze 
 felspar 85, alkali 15 ; felspar 75, gypsum 12, ground 
 ware 12, alkali 1. The intermixture of ground 
 shards is constantly practised, and whenever there is 
 a deficiency of supply, an artificial substitute is pro- 
 vided, a number of thin pieces resembling stilts are 
 
 2 G 
 
450 CHEMISTRY OF POTTERY. 
 
 fabricated, baked well, and ground to an impalpable 
 powder. I met with the senseless remark of a writer, 
 evidently ignorant of the resources of the French, 
 that, because their nation does not supply a natural 
 porcelain clay equal to that of some other of the con- 
 tinental states, the Sevres Manufacturers despair of 
 making their ware equal to those of King-te-ching, 
 Saxony, and Vienna. The progress of chemical and 
 mineralogical science warrants a directly opposite 
 conclusion. l 
 
 The porcelain of Vienna, Frankendal, and other 
 places in Germany, is formed of the tarso and clay 
 from near Passau ; but there is such variations in the 
 proportions or processes, or both, as to cause great 
 difference, as well from each other as from that of 
 Dresden. And equal dissimilarity exists between 
 them and that of Berlin formed of the tarso and clay 
 from the valley of Gatach, above Haussach, in Wir- 
 temberg ; also, those of Villaroy and Orleans, of 
 Naples and Florence, which last possesses many of 
 the excellencies of the best Oriental wares. 
 
 The Vienna hard porcelain has present much 
 silica, little alumine, and very little lime. The soft 
 much lime, sulphate or carbonate, or both, and even 
 soft felspar, and a spice of alkali to economise the 
 fuel ; and because it will not sustain the temperature 
 requisite to bake the felspar glaze, that employed is 
 softer, yet has a smoother appearance when baked. 
 
 Recently has been used in German porcelain 
 carbonate of barytes, or of lime, and little alkali, 
 potash, or soda, for the glaze ; and, for economy of 
 fuel, also to secure the solidity by semi-vitrescence, 
 and increase the translucence, sulphate of lime is 
 introduced ; these alkaline earths and the silica vitri- 
 
BODIES. 451 
 
 tying at the temperature mentioned, page 177. The 
 first baking is at the temperature 6277 Fahrenheit, or 
 40 Wedgwood, or that of baking Delft ware, merely 
 to evaporate the water present with the earths. The 
 ware in this state is very brittle, porous, has a dull 
 grey colour, and little weight, much similar to the 
 wine-cooler or alcarazza, and is ready for its coat- 
 ing or glaze. This is of components readily fusible, 
 because of the necessity of differing from those of the 
 biscuit, which should be refractory alone, and only 
 semi-fusible with the covering ; because was this to 
 soften while the glaze is baking, the fluxing potency 
 of its components would solicit those of the biscuit, 
 and there might result the disaster of the ware sink- 
 ing under its own weight, probably destroying the 
 shapes of vessels, and the fine forms of figures. The 
 ware is first dipped into an alkaline ley, then par- 
 tially dried, and dipped into a fluid of felspar and 
 vinegar, then dried, placed in the (gazettes) seggars 
 and baked 30 to 36 hours. 
 
 In mentioning the relative proportions of the 
 components of porcelain, and also of other kinds of 
 bodies, I wish to be understood, that the following 
 are of general utility ; and when they are com- 
 pounded as directed, the results will be satisfac- 
 tory : 
 
 HARD PORCELAIN. FRITTED BODIES. 
 
 1. Kaolin 75, sal ammoniac 2, borax 23 ; frit twenty-four hours 
 in a kiln ; or, if fritted in seggars. let them be lined witrr Lynn 
 sand 64, dry flint 36 mixed well together (instead of flinting the 
 seggars, as is usual) and no loss will ensue, when the frit is 
 picked. For 
 
 2 G 2 
 
452 
 
 CHEMISTEY OF POTTEEY. 
 
 Body, Grind very well together, frit 45, China clay 40, ball 
 clay 10, old clay shavings 5. 
 
 To every hundredweight ^ oz. of zaffre. 
 
 2. Kaolin 70, borax 20, nitre 5, sal ammoniac 5, frit twenty 
 hours. Grind for Body, frit 45, flint 5, China clay 40, brown 
 clay 5, shavings 5. 
 
 3. Kaolin 60, borax 25, flint 5, nitre 5, sal ammoniac 5. Grind 
 for Body, frit 50, China clay 35, ball clay 5, shavings 10. 
 
 4. Kaolin 75, borax 20, nitre 2^, sal ammoniac 2i. Grind for 
 Body, frit 60, china clay 30, shavings 10. 
 
 RAW BODIES. 
 Kaolin 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 11 
 
 1213 
 
 i 
 
 14jl5 
 
 I 
 
 55 
 
 20 
 10 
 10 
 f> 
 
 50 
 30 
 5 
 10 
 5 
 
 30 
 22 
 20 
 18 
 10 
 
 50 
 30 
 
 14 
 6 
 
 40 
 30 
 10 
 10 
 10 
 
 40 
 37 
 10 
 7 
 6 
 
 50 
 20 
 10 
 15 
 fi 
 
 54 
 20 
 10 
 10 
 f> 
 
 50 
 25 
 8 
 12 
 ft 
 
 56 
 36 
 
 8 
 
 52 
 32 
 10 
 6 
 
 46*45 
 2530 
 1010 
 1310 
 
 fi fi 
 
 3030 
 3030 
 1020 
 1510 
 
 5 ! in 
 
 China clay 
 
 Ball clay 
 
 Shavings 
 
 Flint . 
 
 Here, as in other pages, will be seen how much 
 practice is in advance of theory in the Art of Potting. 
 The fact was often observed, that, although the slip- 
 maker might most carefully obey his instructions, 
 and mix the precise proportions of the components 
 strictly in accordance with the best methods, and 
 the clay itself fabricate ware of much excellence in 
 biscuit, yet it could not be used by the workman, 
 with the usual labour on his part, and to the advan- 
 tage of the Manufacturer, because so very short or 
 deficient in the adhesion of its particles, as not to 
 hold together during the proper manipulations ; thus 
 the clay bat could scarcely be properly beaten, and 
 even when so, it would scarcely bear lifting from the 
 block to the bench and mould. This annoying defect 
 cannot be remedied by any theoretical remarks cur- 
 rent in the chemistry of atoms, and only practice 
 could suggest an efficient remedy. Economy of 
 
BODIES. , 453 
 
 materials causes a mixture of the fragments cut off 
 the vessels by the turner, etc., and of fresh materials, 
 in the slip-tub ; and the presser had noticed an 
 advantage in using such clay, by the additional 
 quantity of sound vessels fabricated from a given 
 weight, than from clay made wholly of fresh ma- 
 terials. Thus originated the opinion, by experience 
 verified, that a body once worked will amalgamate 
 with like components fresh introduced, and the whole 
 be more readily receptive of the manipulations than 
 entirely fresh compounds ; and hence the utility of 
 introducing shavings into the China body. Some- 
 times only shavings of the flint ware best printing 
 body are employed for ball clay, with the other 
 components. When the Middletown Hill felspars 
 were first employed by Mr. Spode, a clay was formed 
 in the usual manner, then the thrower formed strong 
 thick vessels, left them to the green state, and the 
 turner cut all up into very fine shavings, which in 
 suitable proportions the slip-maker introduced into 
 fresh mixtures, from which he made clay for the best 
 porcelain, which answered the workman's purpose. 
 The continuance of the clay in the vault for some 
 days, or weeks, if convenient, will effect an intimate 
 union of particles, which exceeds any produced by 
 mechanical pressure ; and every bubble of air is 
 expelled by frequent slapping and working before 
 either the thrower or presser will form his vessel ; 
 as, if present, expansion in the baking would fracture 
 the article. 
 
 Porcelain biscuit much resembles fine statuary 
 marble, and its surface likewise is without lustre. 
 Hence the vases, figures, etc., fabricated by the 
 
454 CHEMISTRY OF POTTERY. 
 
 continental and English artisans, have much beauty 
 and elegance ; and in accordance with the quality of 
 the components, the biscuit more or less exhibits the 
 elegance of the workmanship ; and the artist having 
 increased the adhesion of the clay by some mucilage, 
 starch, gum, etc., baking increases the beautiful ap- 
 pearance of all the sharp and clear edges and lines, 
 like to fine sculpture, and not possible for glazed 
 articles to exhibit. 
 
 I am not aware of any announcement of a 
 porcelain whose body and glaze are so homogeneous 
 as to save the extra labour and fuel by needing only 
 once baking. Such is the difference in the compo- 
 nents of the bodies and glazes of British porcelains 
 that were the vessels to be dipped in the glaze liquid 
 prior to being once baked, the water in permeating 
 would destroy the adhesion of the clay, and the least 
 disaster would be a shrinking of the shape of the 
 article ; and also, the different contractile properties 
 of biscuit and clay not being provided for in the 
 glaze, the portion unappropriated by the surface of 
 the body would remain in ridges. It is proposed 
 to take well-ground kaolin 30, China clay 50, 
 native phosphate of lime 6, sulphate of barytes 14 ; 
 grind twelve hours, evaporate into clay, and this the 
 thrower and turner must form into shavings, as 
 already stated, to be again ground in the proportions 
 of 80 to 100 per cent, of fresh materials. Of this 
 latter clay must the vessels for sale be fabricated ; 
 and, while each is on the lathe, the turner must 
 apply (as for dipped ware), by the blow-pipe bowl, 
 a liquid of glaze components best petuntse 60, 
 borax 16, carbonate of barytes 16, nitre 4, salt 4 ; or, 
 
BODIES. 455 
 
 75, 10, 10, 5, ; and when moderately dry, wash 
 the inside with the liquid, and dry the whole ready 
 for the seggar and baking. 
 
 SOFT PORCELAIN. 
 
 WE may indulge a smile at the credulity of 
 those persons who assign the introduction of bone 
 earth into the body of soft porcelain to the following 
 derisive remark of a Chinese potter: "The Euro- 
 peans must be a wonderful people, to go about to 
 make a body, whose flesh was to sustain itself without 
 bones." For the fact was obvious in cupels, that at 
 a very high temperature bone earth forms a white 
 opaque enamel. The phosphoric acid present also 
 will blanch any particles of oxide of iron in the clays 
 used. These two properties render bone useful in 
 soft porcelain. 
 
 Being readily solicited by alumine, and even as 
 a hydrate, soliciting moisture from the atmosphere, 
 and at raised temperature decomposing glass or 
 porcelain, need we wonder that the quantity supplied 
 by the bone earth renders the porcelain very soft. 
 Equally will Fluoric Acid solicit silicium, or boron, 
 and form a salt soluble in water ; hence its decom- 
 posing potency on every glaze with which it is in 
 contact. 
 
 A soft porcelain, translucent, brilliant, very 
 white, but light, frangible, and easily injured by 
 changes of temperature, is formed by compounding 
 calcined bones, little gypsum, with grauen, China 
 clay and flint. 
 
456 CHEMISTRY OF POTTERY. 
 
 The bones for the bone earth should be obtained 
 as fresh as possible, and completely divested of all 
 gelatinous particles ; for the lengthened boiling will 
 not effect this, yet injure the calcareous portion, 
 and any particles left in such bone earth, not being 
 receptive of those of the glaze, when such porcelain 
 is enamelled or used, the glaze separates, and the 
 ware is disfigured with black specks. A substitute 
 for bones, and requiring not one-eighth of the 
 weight, will be found in the native phosphate of 
 lime, of a light-brown colour, in immense quantity 
 in the county of Antrim, Ireland. The gypsum 
 may be deprived of its water of crystallisation and 
 translucence by calcination, and even by high tem- 
 perature formed into an opaque milk-coloured 
 enamel ; but, as in the one state it will solidify 
 by soliciting water present, and never is entirely 
 indifferent to the presence of moisture, I regard it 
 as demanding more attention in using it, than is 
 repaid by any resulting advantage. 
 
 The Soft Porcelain formed of a Fritted Body has 
 more firmness and greater density than the kind 
 formed otherwise. The process is an excellent 
 chemical lesson, which needs only to be well conned 
 and steadily pursued, to ensure many advantages to 
 the Manufacture. The frit is usually ground very 
 fine, and then mixed with the proper earths. 
 
 1. Grauen 40, bone earth 40, cullet 20, frit twenty-four 
 hours, and grind. For Body, Mix frit 70, China clay 20, blue 
 clay 10. Stain with zaffre blue. 
 
 2. Grauen 50, bone earth 30, flint 10, cullet 10, grind. For 
 Body Mix frit 65, China clay 20, brown clay 10, flint 5. 
 
BODIES. 457 
 
 3. Grauen 50, bone earth 30, cullet 15, borax 5, grind. For 
 'Body, Mix frit 50, China clay 35, blue clay 5, flint 10. 
 
 4. Grauen 30, flint 25, cullet 25, lime 8, salt 4, borax 8, grind. 
 For Body, Mix frit 40, China clay 48, blue clay 12. 
 
 The chemical combination of lime and silica by 
 very high temperature had long been demonstrated 
 in the fabrication of glass less liable to flee or crack 
 from sudden and great changes of temperature than 
 that from which lime is excluded. This combina- 
 tion is even more intimate when chloride of sodium 
 is present ; and hence the marie of the Crouch ware 
 was useful in assisting the formation of the salt 
 glaze. Whenever lime 25, flint 50, clay 25, or 
 lime 48, flint 40, clay 12, are together at a high 
 temperature, perfect fusion ensues ; but the fusion 
 is only partial of lime 25, flint 75 ; and lime 20, 
 flint 80. Because of this property, porcelain with 
 a minimum dose of lime as a component, while 
 moderately firm and compact, is less refractory at 
 high temperatures. 
 
 A soft porcelain (with many excellencies of the 
 definition, and which without wauving requires 
 baking at a high temperature, but has little cohesion 
 and requires much care in working) is formed (says 
 Mr. Brongniart) of this Frit : nitre, soda, alum, 
 gypsum, sand and salt; for the Body, mix frit 75, 
 clay 25. The proportions are not stated, and the 
 possible mixtures may be in arithmetical progression 
 to the number 720. This body is almost opaque ; its 
 glaze has plus of lead, and is very transparent, yet 
 adapted for enamel colours. 
 
458 
 
 CHEMISTRY OF POTTERY. 
 
 EAW BODIES. 
 Bone earth 
 
 1 
 
 40 
 20 
 25 
 4 
 6 
 
 2 
 
 46 
 18 
 20 
 4 
 
 3 
 
 4 
 
 5 
 
 > 
 
 7 
 
 8 9 
 
 10 
 
 11 
 
 12 
 
 1314 
 
 15 
 
 (50 
 16 
 20 
 4 
 
 30 
 8 
 25 
 
 4 
 3 
 
 10 
 
 20 
 40 
 20 
 
 ib 
 
 10 
 
 28 
 30 
 20 
 10 
 5 
 7 
 
 25 
 25 
 16 
 15 
 9 
 10 
 
 2946 
 3525 
 1620 
 10'... 
 
 42 
 20 
 25 
 
 30 
 20 
 30 
 10 
 5 
 5 
 
 28 
 35 
 18 
 8 
 6 
 5 
 
 2836 
 3020 
 2024 
 
 121 
 
 54 
 16 
 20 
 
 Grauen ... 
 
 China clay 
 
 Blue clay 
 
 Flint 
 
 5... 
 5 9 
 
 5 
 
 8 
 
 .. 10 
 1010 
 
 ib 
 
 Shavings .. 
 
 K 
 
 i.2 
 
 
 The following are the components of the French porcelain made 
 at Chantilly : Limoges felspar 14, porcelain clay 60, carbonate of 
 lime 6, sulphate of lime 10, ground shards 10 ; glazed with felspar 
 75, sulphate of lime 13, ground shards 12. A recent French 
 patent directs Clay 20, oxide of bismuth 40, ground shards 40, 
 without any glaze. The Corsican porcelain has felspar 40, clay 
 40, amianthus 20; and it is extremely light, yet little frangible, 
 and will bear great and sudden alternations of temperature. 
 
 STONE CHINA. 
 
 Grauen 
 China 
 Blue ( 
 Flint . 
 
 1 2 
 
 A O ' A O 
 
 China clay J27 38|25 30 30 32 
 
 Blue clay 18 5i2014|20|20 
 
 48I5042J483538 
 8|25|30 30132 
 5J2014|2020 
 7 7113 8|15|10 
 
 2626303025 
 
 20 26 10 
 
 1616 
 
 1010303525 
 
 28 22 25 30 20 
 
 515 
 
 15 
 
 IRONSTONE. 
 
 Slag, ground. 
 
 DRY BODIES. 
 
 So named because without glaze are inter- 
 mediate between porcelain and flint wares, par- 
 taking the properties of their biscuits. They are 
 different in qualities and colours, and their value is 
 enhanced by their employment to fabricate articles 
 of taste and luxury rather than of general utility. 
 They include the kinds : CHEMICAL UTENSILS, STONE, 
 JASPER, PEARL, CANE, DRAB, RED, BLACK EGYPTIAN, 
 FAWN, BROWN, SAGE, etc. Several are so compact 
 
BODIES. 459 
 
 and vitreous in biscuit, as neither to appropriate nor 
 need a coating or glaze ; yet their surface presents 
 minute pores,as though gas had thence evolved during 
 the baking. The Jasper* and Pearl have usually 
 much embellishment ; and the elegance of the deco- 
 rations is preserved in the sharp, prominent outlines, 
 which would suffer in the ratio of the thickness of 
 glaze applied. The Red is used for Alcarazas, 
 Buxaros, or Demi-Johns, large porous vessels to 
 hold water, yet admit a wine bottle into the cylin- 
 drical part, the outside usually having additional 
 points of surface exhibited in the fruit and foliage 
 decorations, They were invented and are much 
 used in Spain. They are fabricated of clay, com- 
 pounded of flint 36, and red clay or marie 56, brick 
 clay 8, which are worked together with a weak salt 
 ley ; both of whose components being dissipated by 
 the slight baking, the vessel is porous, and yet the 
 whole has adhesion which sustains without any injury 
 the continued oozing of the water through from the 
 inside. These vessels are saturated with water, and 
 then filled to the brim, and if a full bottle be therein, 
 the temperature of its liquor will soon be brought low; 
 it being a property of all substances to communicate 
 
 * I do not recollect hearing why this name was imposed. The 
 Pearl was in consequence of the peculiar whiteness of the ware 
 when first offered for sale. The Porcelain Jasper of Nature is in 
 colour grey, yellow, or blue ; with vitreo-resinous lustre, opaque, 
 hard, and easily frangible, supposed (by Werner) a slate clay, by 
 natural galvanism converted into a kind of porcelain ; Link men- 
 tions that it melts into a white glass with the blow-pipe ; and 
 Eose gives its components Silica 60'75, alumine 27'25, mag- 
 nesia 3-00, alkali 3'66, oxide of iron 2-50, loss 2-84. 
 
460 CHEMISTRY OF POTTERY. 
 
 their atomic motion to all others in contact, with a 
 facility in accordance with the number of surround- 
 ing points presented by the roughness of the surface ; 
 and the atomic motion of the water being diminished 
 by the action of the surrounding atmosphere, as it 
 evaporates through the pores, whatever water remains 
 therein will soon be almost -as cold as ice.* The 
 practice prevails among those merchants who tra- 
 verse the Arabian deserts. The bottles of water are 
 wrapped in w r et cloths, which are carefully kept wet, 
 and the evaporation resulting keeps the water at a 
 temperature most grateful to the palate. 
 
 * The difference of taste in the usage of wares for domestic pur- 
 poses will readily suggest itself to the reader who compares his 
 own experience with the following facts, extracted from a volume 
 by MBS. MEEE HASSAN, an English lady married to a Mussulman 
 of Lucknow : " In the zeenahnah (lady's apartment), china or 
 glass is comparatively little used ; but the common red earthen 
 katorah (or cup shaped like a vase). China bowis, basins, and 
 dishes are used for serving many of the savoury articles of food 
 in ; but it is as common in the privacy of the palace as in the huts 
 of the peasantry to see many choice things introduced at meals 
 served up in the rude earthen platter, many of the delicacies of 
 Asiatic cookery being esteemed more palatable from the earthen 
 flavour of the new vessel in which it is served. I remember feel- 
 ing some dissatisfaction at the rude appearance of the dishes con- 
 taining choice specimens of Indian cookery which poured in on my 
 arrival. In my ignorance I fancied that the Mussulman people 
 must fear I should contaminate their China dishes ; but I soon 
 found that brown ear then platters were used by the nobility from 
 choice, and the viand would want its greatest relish in China or 
 silver vessels. China tea sets are rarely found in the zeenah- 
 nah, tea being used more as a medicine than as a refreshment. 
 The ladies must have a severe cold to induce them to partake of 
 the beverage even as a remedy, but by no means as a luxury." 
 
BODIES 461 
 
 CHEMICAL UTENSILS. 
 
 THE purposes of the laboratory render indis- 
 pensable vessels of earthenware adapted to sustain, 
 uninjured, the action of different powerful agents. 
 The ware employed bears the .name of the first 
 maker, WEDGWOOD, among the chemists of Europe ; 
 and his grandson, the younger Josiah Wedgwood, 
 has brought to the improvement of the ware adequate 
 practical experience and great chemical knowledge. 
 As most Chemical Utensils, on some occasion or other, 
 are required to bear, without failure, considerable 
 rise of temperature, they should be refractory at any 
 degree usually and easily obtained, and continue 
 uninjured by any sudden alternations thereof, as 
 well as from saline or other compounds, in solution or 
 fusion. We cannot preclude silica from all chemical 
 action of such compounds ; but this according ever 
 with the number of points in the surfaces in contact, 
 opportunity for destructive attack will be in the 
 ratio of the comminute state of the silica. The prin- 
 ciple is to preclude cracking, by apportioning the 
 components, so that any slight excess of refractory or 
 fusible may be provided for, and the whole together 
 shall equally expand and contract by rise and fall of 
 temperature. The clay found to fabricate wares best 
 adapted to answer, is compounded of best flint ware 75 
 (entirely free from calcareous particles, which would 
 render the others fusible), and 25 of baked shards in 
 the state of impalpable powder. In some articles the 
 clay has from 5 to 10 per cent, sulphate of barytes, 
 and proportionately less flint. 
 
462 
 
 CHEMISTEY OF POTTERY, 
 
 FKITTED JASPER BODIES. Frit twenty-four hours, grauen 40, 
 50, 35, 40 ; sulphate of lime 30, 50, 26, 40 ; Gullet 24, 24, 12, 12 ; 
 flint 10, 16, 8, 8. Grind twelve hours for Body, frit 32, 50, 
 32, 40 ; china clay 18, 37, 30, 30 ; blue clay 18, 13, 10, 6 ; sul- 
 phate of barytes 32, 32, 30, 34. 
 
 FRITTED PEARL BODIES. Frit twenty-four hours, cullet 76, 
 62, 80, 70; minium (red lead) 22, 20, 20, 24; borax 2, 4, 0, ; 
 nitre 0, 8, 0, 6 ; flint 0, 6, 0, 0. Grind these severally twenty 
 hours for Bodies frit 12, 16, 12, 30, 16; grauen 50, 46, 60, 
 20, 54 ; blue clay 38, 24, 28, 50, 30. 
 
 FRITTED DRAB BODIES. 1. Calcine manganese, and pick and 
 pulverise it. Frit four hours equal weights of manganese calc 
 and nitre ; when cool, grind and evaporate to the specific gravity 
 of best earthenware slip ; and in 92 or 96 of the slip, mix 8 or 4 
 of the ground frit, blunge well together, and evaporate to the con- 
 sistence proper for the w r orkman. 2. Calcine nickel, also man- 
 ganese, which carefully pick and pulverise ; then mix equal weights 
 of the two calcs with like weights of good ochre, yellow oxide of 
 iron, and American bole. Of this compound 12 to 6 parts mix 
 with 88 to 94 parts of flint ware body, No. 3, in soft water, and 
 when properly evaporated, the fabricated ware baked in the dif- 
 ferent rings will have shades, varied from drab to sage. 
 
 EAW BODIES. 
 
 K&oliii 
 
 n 
 1 
 
 EMICALS 
 
 2;3 4 
 
 STONE 
 
 w 
 
 4 
 
 . 
 1 
 
 FAS 
 2 
 
 I'Kl 
 
 3 
 
 \ ' 
 4 
 
 1 
 
 Ps 
 2 
 
 \m 
 3 
 
 1 
 
 4 
 
 4030.. 
 40 
 
 36 
 24 
 25 
 15 
 
 . .. 
 
 50 
 
 &5 
 25 
 
 40146 
 10J12 
 3024 
 1512 
 
 5i 6 
 
 30 
 
 18 
 
 33 
 
 82 
 
 98 
 
 30 
 
 60 
 
 22 
 14 
 
 54 
 
 m 
 
 4 
 
 40 
 
 12 
 44 
 
 4 
 
 
 China clay 
 
 303020 
 304025 
 L 15 
 
 l(i 
 54 
 
 17 
 30 
 
 Ca 
 
 3o 
 
 1730 
 
 1728 
 6... 
 
 b. Bar\ 
 
 27110 
 
 14 
 
 18 
 12 
 
 tes 
 28 
 
 :32 
 
 14 
 10 
 
 14 
 
 Blue clay 
 Flint 
 
 Cullet . 
 
 
 i 
 i... 
 
 el 4 
 
 1 
 
 KAW BODIES. 1 
 
 IORTA 
 2 3 
 
 R 
 
 4 
 
 1 
 
 Di 
 2 
 
 A 1! 
 
 3 
 
 4 
 
 1 
 
 r>i 
 2 
 
 )\V. 
 
 3 
 
 * 
 4 
 
 1 
 
 FA 
 
 .2 
 
 \VN 
 
 3 
 
 4 
 
 Grauen 48 
 
 33 
 20 
 25 
 
 11 
 11 
 
 40 
 20 
 25 
 
 10 
 
 5 
 
 28 
 54 
 
 io 8 
 
 45 
 6 
 
 27 
 
 40 
 12 
 24 
 
 40 
 20 
 20 
 
 40 
 10 
 
 6 
 
 44 
 8 
 40 
 2 
 
 18 
 
 40 
 10 
 35 
 2 
 
 10 
 
 20 
 12 
 55 
 8 
 
 6 
 
 ib 
 
 20 
 60 
 
 4 
 
 15 
 10 
 30 
 5 
 50 
 
 5 
 
 :V() 
 10 
 55 
 
 10 
 15 
 5 
 
 70 
 
 10 
 
 7 
 8 
 75 
 
 China clay 24 
 
 Ball clay . . .24 
 
 Flint i 2 
 
 Marie (Eed) 1 2 
 
 20 
 
 20 
 4 
 
 1(5 
 4 
 
 40 
 4 
 
 Manganese... 
 
BODIES. 
 
 463 
 
 RAW BODIES. 
 
 Ball clay 
 Marie (Black) 
 
 1 
 
 CA 
 
 2 
 
 N T E 
 
 8 
 
 4 
 
 Ri 
 1 
 
 :D 
 2 
 
 Po 
 3 
 
 K. 
 
 4 
 
 EG 
 1 2 
 
 iTPTIA 
 
 3|4 
 
 N 1 
 
 5 
 
 3L, 
 
 6 
 
 iCK 
 
 7 
 
 8 
 
 1816 
 60,55 
 
 24 
 
 66 
 
 20 
 70 
 
 40 
 25 
 
 40 
 30 
 
 10 
 
 40 
 
 20 
 40 
 
 4653 
 1412 
 
 8 2 
 30i33 
 
 2!.. 
 
 50 
 8 
 3 
 36 
 8 
 
 37 
 10 
 3 
 40 
 10 
 
 40 
 15 
 5 
 
 40 
 
 50 
 14 
 5 
 25 
 6 
 
 48 
 12 
 6 
 24 
 10 
 
 44 
 16 
 6 
 
 30 
 
 4 
 
 Manganese 
 
 Calcined ochre 
 Brick clav... 
 
 4 
 18 
 
 Is 
 
 26 
 
 2 
 8 
 
 
 
 
 
 40 
 
 10 
 
 35 
 
 30 
 
 50 
 
 The more carefully the slips are prepared and 
 lawned, the more will improve the fine grain and 
 general appearance of these several wares ; while a 
 very useful lesson is supplied in the varied behaviour 
 of the silicic acid to the substances with which it is 
 brought into contact by raised temperature. The 
 best mortar and stone will be found dense, compact, 
 vitreous in fracture, durable (but not translucent) as 
 porcelain, w r ith indifference to the action of acid or 
 alkali when baked in the first ring of biscuit-oven. I 
 am of opinion that there is a chemical cause for the 
 absence of glaze from jasper and pearl ; the high 
 temperature of the baking process would render the 
 acid phosphoric, boracic, or arsenic present with 
 some component of the glaze combinative with the 
 heated sulphuric acid which evolves from the sul- 
 phate of barytes, to which no glaze yet formed 
 remains indifferent. The marie for the porous ware 
 cannot be spoiled by weathering ; it is passed through 
 a 14 law^n, and mixed with the others passed through 
 a 16 lawn, and the ware is baked at the top of the 
 gloss-oven. The manganese should be free from cal- 
 careous particles, that the tea-pots may not crack by 
 the sudden change of temperature on using them. 
 There appeared a necessity, not to say utility, for 
 adopting the centessimal proportions, as greater 
 
464 CHEMISTEY OF POTTEKY. 
 
 accuracy is thereby ensured, even in very large quan- 
 tities. Any additions to the stated proportions will 
 alter the results much beyond what might be conjec- 
 tured. Injurious results may ensue from using flint 
 ground with chert having present an extra proportion 
 of carbonate of lime ; the small portion abraded 
 rendering the biscuit more vitrescent, ovens full of 
 such ware have sunk down at the usual temperature 
 ere the cause was discovered. The tint will be more 
 or less vivid, as the dry bodies are baked in the first, 
 second, or third ring of the biscuit-oven. 
 
 EARTHEN WARE. 
 
 FLINT WARE. QUEEN'S WARE. The best kind 
 in biscuit is fine but opaque ; in texture and grain 
 coarser than porcelain, fracture porous like common 
 lump-sugar, not vitreous nor translucent, moderately 
 dense, sonorous when struck, hard, firm, and durable ; 
 and it is covered with a rich glaze, fine, clear, vitreous, 
 free from specks, transparent to show the embellish- 
 ments of the biscuit, and scarcely affected by acids, 
 alkalies, or sudden alternations of temperature.* 
 
 * There will be few of my readers disposed to believe, that when 
 the subjoined eulogy on Staffordshire flint ware was written, of 
 the twenty Manufacturers who supplied the demand mentioned, it 
 was the intention of Faujas de St. Fond to apply solely to Wedg- 
 wood, to whose ware it has been restricted by the partiality of 
 friendship. " Its excellent workmanship, its solidity, the advan- 
 tage it possesses of sustaining the action of fire, its fine glaze im- 
 penetrable to acids, the beauty and convenience of its form, and 
 the cheapness of its price, have given rise to a commerce so active 
 
BODIES. 
 
 465 
 
 QUEEN'S WARE AND CREAM-COLOUR BODIES 
 
 Flint 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 6J7 
 
 8 
 
 9 
 
 10 
 
 11 
 
 12 
 
 
 1(5 
 16 
 24 
 16 
 14 
 6 
 
 20 
 24 
 30 
 12 
 4 
 
 18 
 10 
 30 
 16 
 12 
 8 
 
 17 
 17 
 50 
 
 "8 
 
 24 ! 20 ! 20 
 ..".! 16 
 
 22 
 18 
 30 
 14 
 
 "6 
 
 10 
 
 24 
 14 
 24 
 12 
 12 
 6 
 8 
 
 25 
 
 18 
 20 
 20 
 9 
 
 "8 
 
 20 
 16 
 30 
 16 
 
 8 
 10 
 
 25 
 16 
 28 
 12 
 7 
 
 12 
 
 China clay 
 
 Blue clay 
 
 363025 
 1620110 
 
 4 ! 810 
 10 ( 10 9 
 101210 
 
 Black clay 
 Brown clay 
 
 Cracking clay 
 
 Shavinsrs... 
 
 8 
 
 10 
 
 6 
 
 8 
 
 BLUE AND FANCY PRINTED BODIES: 
 
 Grauen 
 
 1 
 
 15 
 
 15 
 14 
 8 
 20 
 18 
 5 
 
 2 
 
 3 
 
 6 
 20 
 15 
 6 
 
 28 
 15 
 10 
 
 4 
 
 5 
 
 6 
 
 6 
 20 
 14 
 8 
 22 
 16 
 4 
 10 
 
 7 
 
 8 
 25 
 15 
 12 
 28 
 10 
 2 
 
 8 
 
 8 
 20 
 14 
 6 
 33 
 
 ( J 
 10 
 
 9 
 
 6 
 24 
 18 
 8 
 30 
 4 
 5 
 5 
 
 10 
 
 6 
 18 
 20 
 11 
 45 
 
 11 
 
 10 
 20 
 15 
 8 
 40 
 
 12 
 
 12 
 24 
 18 
 10 
 36 
 
 
 10 
 16 
 12 
 10 
 25 
 17 
 
 4 
 24 
 12 
 
 8 
 26 
 10 
 
 8 
 18 
 18 
 10 
 32 
 4 
 10 
 
 Flint 
 
 China clay 
 
 Shavings 
 
 Blue clay 
 
 Black clay . . 
 
 Brown clay 
 
 : 
 
 7 
 
 ... 
 
 Cracking; clay... 
 
 5 
 
 10 
 
 
 16 
 
 and so universal, that in travelling from Paris to Petersburg!!, 
 from Amsterdam to the farthest part of Sweden, and from Dunkirk 
 to the extremity of the south of France, one is served at every 
 inn upon English Ware. Spain, Portugal, and Italy are supplied 
 with it, and vessels are loaded with it for the East Indies, the 
 West Indies, and the continent of America." 
 
 How different is the opinion of Guy ton Morveau : " The flint 
 and pipe-clay (or Queen's Ware) is in biscuit more solid than 
 Delft, as being composed of better clays and earth, of flints calcined 
 and in comminution, and previously baked before applying the 
 glaze (more fusible than that of Delft), a real glass, not enduring 
 equal heat, but subject to crack, easily scratches, and into these 
 oily matters penetrate, spot the biscuit, and when the lead is in 
 excess, as it often is, oils and vegetable acids decompose it, and 
 danger attends its use. Very seldom will this ware completely 
 resist the edge of a knife, and after this, it fails before the test of 
 boiling acetic acid, or the yolk of egg boiled hard." 
 
 2 H 
 
466 
 
 CHEMISTRY OF POTTERY. 
 
 DIPPED & MOCHA. 123456123456 CHALKY. 
 
 i 
 
 Grauen j 446446 
 
 Flint 30 25i30 28 25 28 20 26 32 30 28 34 
 
 China clay 20 18|22 20 18 20 24 20 26 18^24 20 
 
 Blue clay' 24 30126 32 30 40 24 20 16 28;20 30 
 
 Brown clay 610 2 6 17 ... 12J10 ... 10'14 
 
 Black clay 10 71014... 2...I10UO 
 
 Shavings 101010101010 6| 
 
 101010101010 
 
 Seggar Body Grey marl 50, black marl 25, ground seggars 
 '25. Altered & little for the gloss oven. 
 
 FOR EINGS AND STILTS. PEGS. SAUCER MOULDS. 
 
 Bone earth 25 C. clay 12 
 
 Black clay 84 37 92 28 
 
 Grauen 25 
 
 Flint .'. 16 5 8 60 
 
 Plaster 8 
 
 Pass through a 6 lawn. 
 
 FOR FIGURES ON JASPER. 
 
 Bone earth 18 22 
 
 Flint 6 10 
 
 Carbonate of Barytes.. 38 30 
 
 Blue clay 38 38 
 
 The advantage of good water for the purpose of 
 blunging is generally admitted ; yet I have not 
 known any instance of distilled water having been 
 tried. Although there is no probability of an 
 adequate supply, there could be no impropriety in 
 collecting and using what may be obtained from 
 the steam-engines. 
 
 Of the incertitude in mixing the clays, up to a 
 very recent date, I shall exhibit four proofs (omitting, 
 from respect to private worth, the names of the 
 
BODIES. 
 
 467 
 
 Manufacturers) copied from a Book of Recipes, 
 without owner's name, found on Fenton Park Hill, 
 in May, 1832 : 
 
 6 Barrowfuls of Brick clay. 
 4 Ditto Blue. 
 
 2 Ditto Cracking. 
 
 8 of the above in slip. 
 4 Cornwall clay. 
 
 7 Flint. l^r Cornwall stone. 
 
 3 Barrowfuls Black clay. 
 2 Ditto Brown. 
 2 Ditto Blue. 
 40 Ibs. Cornish stone. 
 
 Of this slip 6 or 6| to 1 Flint 
 twice through the lawns. 
 Clay slip 24 oz. to pint. 
 Flint 30 do. 
 
 Cor. Stone 24 do. 
 
 In Slip-tub Ball clay. 
 
 11| inch. Ball clay. 20 Blue. 
 4f do. China clay. 5 Black. 
 3i do. Flint 2| Brown. 
 
 24 Quarts Cornish stone. 
 Or, these two : 
 
 28 inch. Ball clay. 300 gals. Slip. 
 7 Flint. 70 Flint. 
 
 2| China clay. 20 C. clay, 
 i Cor. stone. 30 C. stone. 
 
 And may be used, 
 
 3f inches in slip-tub. 
 1 do. 
 J do. 
 
 54 of Clay slip. 
 
 18 China clay ; or, 
 
 16 Flint. 
 
 16 pailfuls of Blue clay 
 4 do. China clay 
 4 do. Flint 
 
 24 oz. to pint. 
 24 do. 
 
 31 do. 
 
 Now, as the clay slip may be 27, flint 32, and 
 stone 33 ounces per pint, and this may not be 
 known or corrected by the slip maker, needs there 
 be any surprise, that from directions thus indefinite 
 considerable losses have frequently been experienced, 
 although every care in the manipulations has been 
 taken to cause close integration, toughness, and 
 expulsion of air-bubbles, by often wedging and 
 slapping the clay. 
 
468 CHEMISTRY OF POTTERY. 
 
 Because of the great difference of circumstances 
 which influence the peculiar properties of wares, in 
 the present state of knowledge no certain method, 
 independent of synthetical experiment, can be devised 
 for their improvement ; but in scarcely any instance 
 will the labour of trials fail to be amply repaid 
 by the certainty with which they suggest the 
 best methods ; and more especially will this ensue 
 on discovering that all defects in excellence are 
 consequent on those in the adapted proportions of 
 the components. Hence, adding the study of the 
 theory to that of the practice is the most interesting 
 and useful method by which the intelligence of the 
 former can elucidate the experience of the latter. 
 The man intimately acquainted with the manipula- 
 tions of an Art, with more ease and advantage 
 acquires further knowledge, derives additional infor- 
 mation from the suggestions of science, than he who 
 is without either practice or habit in the processes ; 
 to whom, whatever is mentioned, can refer merely 
 to things in the abstract ; the principles stated being 
 applicable to subjects of which he is devoid of ideas, 
 either assume a wrong direction or soon are forgotten. 
 But the other causes all the rays of light supplied 
 to bear on his own experience ; his practice, his own 
 observations confirm and corroborate the information 
 and suggestions received ; while with every depart- 
 ment of theory, his productions in one way or other 
 identify themselves. 
 
469 ] 
 
 CHAPTER IV. 
 
 GLAZES. 
 
 PROBABLY the mere inspection of an article of 
 pottery in the state of biscuit would suggest that it 
 is a porous compound, as would be demonstrated by 
 immersing it in water ; and as such, by recipience 
 and retention of liquids, decomposable, destructive 
 of its cohesive properties, and therefore inconvenient 
 for the useful purposes of domestic life. This (Jefect 
 originates the application of a coating, varnish, or 
 GLAZE ; and the perfection of the Art aims, while 
 aiding the durability of the ware, to improve its 
 general appearance. 
 
 Problem. It is required to form a verifiable compound, as a 
 GLAZE or coating of ware, either opaque or translucent, which 
 when baked shall be transparent for printed, or semi-opaque for 
 enamel, yet neither injure, nor be injured by any colours with 
 which it may be in contact. 
 
 The glaze being formed by raised temperature 
 exciting simultaneously the momenta of the com- 
 binative potencies of the respective components, in 
 the correlative states of agent and recipient, the 
 plus and minus of the excitement, the more fusible 
 
470 CHEMISTRY OF POTTERY. 
 
 components must ever be carefully proportioned to 
 the others, that the chemical combination of the 
 whole may be promoted, while the expansion of the 
 orbital spaces of the minute particles may produce 
 and secure the requisite transparency. 
 
 This vitrification of heterogeneous substances 
 for the Arts is producing a fresh compound, 
 homogeneous, varying as elastic and transparent, 
 and whose fragments exhibit the vitreous fracture. 
 It results from rise of temperature increasing the 
 momenta of the combinative potencies of the com- 
 ponents fusible per se, because of their natural dose 
 of alkali, which yet at that temperature would not 
 alone affect or be affected by other substances present, 
 though all soften together. Whether the method of 
 preparing vitreous colours, or of making glass, did 
 or did not suggest a similar formation of glazes, I 
 cannot assert ; but the practice obtains preference for 
 all best wares. 
 
 Fritting (another term for vitrification) is sub- 
 jecting certain components of a glaze to a slow rise 
 of temperature, affecting whatever acid and alkali 
 may be present, dissipating all their moisture, water 
 of crystallisation, and carbonic acid gas, then con- 
 tinuing the raised temperature till all carbonaceous 
 ingredients are decomposed without any mineral 
 being volatilised, thereby preparing the results for 
 ready suspension in water in the dipping tub, and 
 precluding the liability to intumesce during the 
 process of glaze baking. 
 
 A frit is not necessarily and always a simple 
 agent ; the mixture of which it is formed usually has 
 present different combinations, and the components 
 
GLAZES. 471 
 
 employed do not act immediately, but by the result- 
 ing combinations. The chief component may be 
 one that varies its combinative potency, according 
 to its actual condition, and also the circumstances of 
 the combination, and the reciprocal potencies of the 
 substances in contact. 
 
 When such is the condition of the frit, whether 
 the process be continued, according to the com- 
 ponents present, 6, 12, 20, or 30 hours, and however 
 much reduced may be the bulk of the components, 
 and also the levity of the mass, through the whole, 
 from the surface to the bottom, will be successive 
 strata, each of which has some of the components 
 less intimately mixed than the others, and is of a 
 density intermediate between the stratum above and 
 that below, instead of the whole being uniform. 
 
 The beautiful dense transparence of the frit 
 being in proportion to its duration of the tranquil 
 state while at the raised temperature, it commences, 
 without always completing the chemical union of the 
 silica, alkali, and oxide present ; and an opinion is 
 current, that afterwards, while attaining the tem- 
 perature of the atmosphere, the fluxes fall, the com- 
 ponents assume the order of their specific gravities, 
 and render long grinding indispensable. 
 
 The exorbitant price of the felspars (fifteen 
 guineas for the petuntse, and half that sum for the 
 kaolin), also probably the deficient supply because of 
 a dispute among the members of the mining company, 
 threw the Manufacturers on their own resources ; and 
 the preparation of substitute* for these felspars was 
 the commencement of a grand chemical lesson, the 
 compounding of alkaline glazes. Doubtless some 
 of these were in the proportions stated in the 
 
472 CHEMISTRY OF POTTERY. 
 
 published analysis of felspar ; but, either from some 
 imperfection in these, as they are not in accordance 
 with the multiples of the combinative potencies of 
 the components, or oversight, and of consequent 
 disregard of some important component, there is 
 remarkable difference. The felspars analysed may 
 be those of granite, which have silica, alumine, 
 alkali, lime and iron present, and the alkali being 
 regarded as potash, though now proved to be lithia ; 
 that failures in the attempts to imitate Nature have 
 occurred, needs not be a matter of surprise. 
 
 Whenever the components of alkaline glazes 
 are not in equivalent proportions, they are com- 
 paratively less useful, have less combinative potency, 
 and are more easily affected and deranged by other 
 substances as the series of components increases. 
 
 Alkaline, or Fritted Glazes, whether formed of 
 natural or artificial felspar, are becoming more 
 general, because of these useful and excellent pro- 
 perties : the additional doses of alkali present cause 
 the components to flow together at a temperature 
 lower than would fuse some of them if alone, and 
 than will fuse the raw glazes ; to promote the 
 fusibility of the surface with which they first come 
 into mere contact ; to be better adapted for chemical 
 combination, and flow free, even, and thin on the 
 ware ; by baking formed into a beautiful coating of 
 perfect glass, which will accord so readily with the 
 pyrometric expansibility of the biscuit surface as 
 seldom or never to craze. 
 
 The ratios of the specific gravities of lead and 
 alkaline glazes as 11 to 2. Even was the consistence 
 of both the same, the latter is cheaper, because a less 
 weight will answer the designed purpose. But to 
 
GLAZES. 473 
 
 obtain a like result, the former is required to be 
 twice as thick as the latter. By different dippers 
 the fact has been noticed that like weights of the 
 glazes covered plates in the proportion of 1 to 5 ; 
 therefore, if their excellence were equal, and their 
 expense as 1 to 5, the alkaline is the cheaper, 
 because of its greater quantity, without taking into 
 the account the diminished expense in baking. 
 
 This most regretted defect of the Manufacture, 
 - crazing, the failure of the glaze, by innumerable 
 peculiar crystallisations with cleavages in various 
 directions, whatever be the cause in the censures 
 consequent, implicates all the Manufacturers and 
 injures them nationally, as competing with those 
 of China and Europe, and locally, by inducing a 
 character of excellence in favour of the wares 
 fabricated in other places in Britain. 
 
 The glaze-baking process may not have raised 
 and a sufficient time continued the ware at a suitable 
 temperature ; and before the glaze has been cool it 
 may have been exposed to the sudden action of the 
 atmosphere. When ware thus defective is used for 
 domestic purposes, as bowls for soups, dishes for 
 meat pies, and similar uses, we find the absorbent 
 potency of alumine for oils, animal and vegetable, 
 during raised temperature, almost equal to that for 
 water (page 233), independent of the decomposition 
 of materials, particularly renders obvious the failure 
 of the glaze or crazing. 
 
 That it is consequent on the incompatibility of 
 the compounds the components being unequal in 
 fusibility, or imperfectly combining with those of the 
 body during baking or fresh compounds resulting 
 from the process, we assume from the fact, that it 
 
474 CHEMISTRY OF POTTERY. 
 
 never occurs when the components are properly 
 adapted for the purpose, and to those of the body ; 
 and agreeably to their combinative potencies are 
 mixed by proper manipulations. The particles, 
 solicited in opposite directions, with natural 
 tendency to preserve the respective dimensions of 
 their orbital spaces, and yet by reciprocal combina- 
 tive potencies solicited to remain in contact, only 
 by the simultaneous expansibility of the orbital 
 spaces as far as may be required by the pyrometric 
 expansion of the biscuit, can have their continuity 
 on the surface preserved. Whatever prevents or 
 separates any portion of this, by affecting the equili- 
 brium of this simultaneous expansibility of all the 
 particles, instead of equalising the potencies of the 
 components, destroys the continuity of the whole. 
 The susceptibility of crystalline substances to resume 
 that arrangement of particles on every favourable 
 opportunity, instructs us to supersede this, and 
 consequent crazing, in the compounding of glazes : 
 
 Pulverise a quartz crystal very fine, and mix the powder in a 
 watery solution of borax, into which fluid dip biscuit pot shards,, 
 and any thick portion will resume the crystal figures. 
 
 The glaze components must quickly separate 
 from the water, as this is appropriated by the 
 biscuit, with whose components and pyrometrical 
 expansibility they must have some chemical re- 
 ciprocity, and speedily dry into a thin covering 
 of all the surface, with which they must readily 
 incorporate by fusion during the baking, and form 
 a perfect and durable glass, improving the appear- 
 ance while promoting the durability of the ware, 
 which otherwise would be liable to craze.. 
 
GLAZES. 
 
 475 
 
 HARD PORCELAIN FRITTED GLAZES : Frit 24 
 hours, pick and pulverise, 
 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 11 
 
 12 
 
 13 
 
 14 
 
 15 
 
 (>() 
 10 
 4 
 
 14 
 6 
 
 75 
 12 
 3 
 10 
 
 65 
 
 14 
 8 
 
 10 
 
 3 
 
 56 
 12 
 9 
 
 15 
 8 
 
 60 
 
 10 
 8 
 16 
 
 70 
 7 
 10 
 
 10 
 ft 
 
 60 
 10 
 (5 
 :-5() 
 
 60 
 10 
 6 
 24 
 
 52 
 
 12 
 6 
 
 30 
 
 80 
 
 10 
 4 
 6 
 
 67 
 
 12 
 6 
 
 10 
 5 
 
 58 
 
 10 
 
 8 
 
 29 
 4 
 
 56 
 8 
 6 
 
 20 
 8 
 
 2 
 
 (34 
 14 
 6 
 
 10 
 
 72 
 10 
 5 
 5 
 
 Garb Barytes 
 
 Garb Lime 
 
 Borax 
 Boracic acid 
 Soda 
 
 
 
 Nitre... 
 
 
 
 6l ' 
 
 
 
 
 
 6 
 
 8 
 
 With 100 parts of each grind, respectively for 
 use, 25 carbonate or white lead, for 1 to 5, and 10 to 
 15 ; from 6 to 9, borax instead of lead, for the four 
 fritted bodies.* 
 
 SOFT PORCELAIN FRITTED 
 hours, pick and pulverise, 
 
 GLAZES : Frit 24 
 
 Grauen 
 
 1 
 
 2 
 
 3 
 
 4< 
 17 
 
 70 
 
 5 
 13 
 
 78 
 10 
 
 6|7 
 
 8 
 ~ 
 
 9 
 
 10 
 
 11 
 
 12 
 
 13 
 
 14 
 
 15 
 
 44 
 18 
 ;*o 
 
 31 
 10 
 38 
 
 24 
 6 
 48 
 
 20 
 
 
 
 
 25 
 14 
 
 25 
 25 
 
 28 
 
 20 
 
 25 
 
 20 
 
 Flint 
 
 lol...... 
 
 406970 
 14 
 
 75 
 15 
 
 68 
 20 
 
 7(5 
 14 
 
 Gullet 
 
 Minium 
 
 40 
 
 16 
 4 
 
 2 
 
 40 
 10 
 
 48 
 4 
 
 45 
 6 
 4 
 
 Litharge .. 
 
 
 
 
 
 18 
 
 22 
 
 Borax 
 
 4 
 4 
 
 20 
 1 
 
 20 
 2 
 
 4 
 9 
 
 
 
 Nitre 
 
 4 
 
 6 8 
 
 ! 4 
 
 4 
 
 4 
 
 7 
 3 
 
 2 
 
 4 
 
 6 
 
 4 
 
 Arsenic... 
 
 * " Among the results of the synthetical essays in my labora- 
 tory, at the Imperial Polytechnic School, I obtained a glass 
 perfectly similar to that afforded me by the felspar of Baveno, by 
 urging to fusion, in a platinum crucible, a mixture of 62 silica, 
 16alumine, 10 lime and 12 potash." GUYTON MOBVEAU. This 
 most excellent lesson has been before the public almost 40 years, 
 yet I cannot find any instance of its having been studied. When 
 it was first noticed by myself, I was equally surprised and gratified 
 by its close accordance with the principle for which I was seeking 
 examples as supporters. 
 
476 
 
 CHEMISTRY OF POTTERY. 
 
 With 100 parts of the first 6, grind '20 or 25 of 
 white lead ; with the next 5, grind grauen 10, white 
 lead 15 ; with others, grauen 15, litharge 10. With 
 50 parts each of 3 and 5, also of 8 and 10, and 7 and 
 11, grind for the four fritted bodies grauen 20, borax 
 15, or 25 and 15, 30 and 15, 27 and 18. 
 
 The following are in the precise form communi 
 cated : 
 
 John Eiley. 
 
 Frit Gullet 16 22 
 
 Bed lead... 5 5 
 
 Arsenic... 1 1 
 
 Salt 1 
 
 Nitre 1 1 
 
 Grind with : 
 
 White lead 25 22 
 
 C. Stone... 14 12 
 
 Flint 6 5 
 
 Frit . . 6 9 
 
 Joseph Marsh. 
 
 16 52 
 
 1 14 Litharge. 
 1 3 
 
 24 
 
 14 
 
 6 
 
 8 
 
 6 
 
 93 
 45 
 25 
 19 
 
 Flow with equal weight of salt, soda and potash. 
 
 George Dean. 
 
 Gullet 27 18 
 
 Bed lead 15 7 
 
 Cornwall stone 13 8 
 
 Flint 11 16 
 
 Borax 12 10 
 
 Soda 5 2 
 
 Tin ash 2 1 
 
 B. Gale 1 1 
 
 Frit 75, White lead 25 
 
 Sampson Daniel. 
 
 16 18 
 34 16 
 30 
 
 25 
 
 28 
 
 10 
 
 4 
 
 1 
 
 8 
 38 
 23 
 5 
 4 
 1 
 
 Frit 60, White lead 40. 
 
GLAZES. 
 
 477 
 
 HARD * AND SOFT t PORCELAIN RAW GLAZES : 
 
 Petuntse 
 
 * 
 1 
 
 # 
 2 
 
 3 
 
 4 
 
 * 
 5 
 
 6 
 
 * 
 7 
 
 89 
 
 4. 
 
 10 
 
 ii 
 
 * 
 12 
 
 * 
 13 
 
 t^* 
 1415 
 
 16 
 
 70 
 
 60 
 
 30 
 
 
 fin 
 
 
 fin 
 
 
 
 
 fiO 
 
 35 
 
 fifi 
 
 
 Grauen 
 
 35 
 
 14 
 
 20 
 
 10 
 
 3040 
 
 45 
 
 30 
 
 "8 
 4 
 
 12 
 5 
 
 32 
 
 "2 
 9 
 
 18 
 20 
 
 6 
 3 
 
 95 
 
 28 
 
 *2 
 6 
 10 
 37 
 
 Garb Barytes 
 
 6 
 4 
 
 12 
 4 
 
 Garb Lime ... 
 
 2 
 8 
 
 12 
 31 
 
 2 
 
 10 
 18 
 10 
 
 5 
 
 j 
 
 12 
 
 47 
 
 .? 
 
 91 
 
 3 4 
 812 
 1223 
 36... 
 
 2 
 6 
 10 
 25 
 
 2 
 7 
 
 20 
 25 
 
 Flint 
 
 Gullet 
 
 
 
 Litharge 
 
 
 
 Borax 
 
 20 
 
 22 
 
 9 
 
 Nitre 
 
 
 
 3 
 
 
 1 
 
 3 
 
 
 2 
 
 4 
 10 
 
 3 
 
 7 
 
 18 
 
 4 
 12 
 32 
 
 5 
 
 14 
 
 1 
 
 "5 
 12 
 
 Boracic acid 
 
 
 
 5 
 12 
 
 7 
 18 
 
 3 
 
 10 
 
 4 
 10 
 
 
 31 4 
 
 814 
 
 3 
 
 9 
 
 Soda... 
 
 
 
 CREAM-COLOUR RAW GLAZES : 
 
 Grauen 
 
 Flint 
 
 Gullet 
 
 White lead 
 
 1 
 
 2|3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 1112 
 
 23 
 12 
 17 
 
 48 
 
 2025 
 1510 
 2515 
 4050 
 
 30 
 14 
 
 56 
 
 26 
 8 
 
 16 
 50 
 
 27 
 10 
 15 
 
 48 
 
 32 
 20 
 
 48 
 
 26 
 10 
 12 
 52 
 
 22 
 8 
 
 10 
 60 
 
 36 
 8 
 
 10 
 
 46 
 
 3440 
 1610 
 
 5050 
 
 BLUE PRINTED RAW GLAZES : 
 
 1 
 
 Grauen 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 11 
 
 40 
 6 
 25 
 
 12 
 
 28 
 4 
 16 
 
 
 25 
 3 
 
 10 
 46 
 
 35 
 
 4 
 12 
 
 20 
 3 
 10 
 
 25 
 
 3 
 
 12 
 
 38 
 
 30 
 5 
 15 
 30 
 
 40J45 
 6|4 
 1812 
 91 
 
 30 
 3 
 20 
 
 32 
 3 
 18 
 
 07 
 
 40 
 
 5 
 20 
 
 Garb. Lime 
 
 Flint 
 
 Litharge 
 
 White lead 
 
 
 36 
 
 49 
 
 
 
 14 
 
 
 95 
 
 
 15 
 
 13 
 
 30 
 6 
 16 
 
 Boracic acid 
 
 
 6 
 
 
 fi 
 
 
 fi 
 
 
 Soda 
 Borax . . 
 
 16 
 
 13 
 
 18 
 
 16 
 
 20 
 
 16 
 
 18 
 
 16 
 
 20 
 
 20 
 
 16 
 
478 CHEMISTRY OF POTTERY. 
 
 FRITTED GLAZES. Frit 24 hours, pick and pulverise. If the 
 frit be in seggars, let them be lined with dry flint 33, and Lynn 
 sand 67 parts, by which much loss in picking will be prevented. 
 
 1. Frit, cullet 70, litharge 18, nitre 8,* arsenic 3, zaffre 1. 
 For glaze, grind together ; for printed, frit 12, grauen 26, flint 12, 
 and in glaze mill mix with white lead 50 ; for enamel, frit 6, 
 grauen 24, flint 16, and in glaze mill mix with litharge 54 ; for 
 brown line (chalky), frit 6, grauen 30, flint 8, cullet 4, borax 2, 
 and in glaze mill mix with white lead 50 ; for dipped and mocha, 
 frit 15, grauen 25, flint 10, and in glaze mill mix with litharge 50. 
 
 2. Frit, cullet 70, litharge 22, nitre 4, arsenic 4, zaffre 1. 
 For glaze, grind together; for printed, frit 24, grauen 40, flint 36, 
 and mix equal weights of the ground glaze components and litharge ; 
 for coloured, frit 32, grauen 48, flint 20, and mix equal weights 
 of glaze and white lead ; for dipped and mocha, frit 26, grauen 
 52, flint 22, and mix equal weights of glaze and litharge ; for 
 cream-coloured, frit 36, cullet 48, common glass 16, and mix 
 equal weights of glaze and white lead. 
 
 3. Frit, separate, cullet 80, red lead 12, nitre 4, salt 4 ; also 
 flint 87 and borax 13 ; mix equal quantities of these frits, and 
 grind ; then for glaze, for printed, mix frit 36, grauen 30, white 
 lead 34 ; for enamel, mix frit 28, grauen 34, white lead 38. 
 
 4. Frit, grauen 36, cullet 32, flint 12, borax 12, nitre 8 ; 
 grind together for printed, frit 60, flint 10, white lead 30. The 
 like mixture of flint and lead with 
 
 5. Frit, grauen 18, cullet 10, flint 30, potash 12, bone-earth 
 15, and Lynn sand 15. 
 
 6. Frit, grauen 34, flint 18, borax 25, red lead 18, tin-ash f 5 ; 
 
 * The Nitre is useful by promoting the high heat to readily fuse the whole 
 mass ; for, combined with potass, the nitric acid sustains a higher heat than 
 with any other base ; and, by its generating carbonic acid gas, improves the 
 colour of the glaze. 
 
 f The Oxide of Tin may be prepared for glazes by the following processes : 
 melt block-tin and keep just melted until the whole is converted into a grey 
 powder. (If the heat be too great, the colour will be straw-yellow.) The usual 
 oxide is prepared by (a) dropping into cold water the tin melted in a ladle ; 
 (b) the fine lamina of metal are placed on a flinted dish, between two layers 
 of nitre in powder, and calcined ; the powder is removed, and the remaining 
 metal similarly treated. Or, the oxide purchased often is adulterated with lead, 
 
GLAZES. 479 
 
 grind together frit 75, grauen 10, flint 15 ; and mix glaze 60, 
 white lead 40, for printed ; and glaze 70, litharge 30, for enamel. 
 
 7. Frit, grauen 36, flint 17, borax 20, red lead 24, tin-ash 3 ; 
 grind together frit 16, grauen 46, cullet 18, flint 20 ; mix glaze 
 54, and white lead 46. 
 
 8. Frit, separate, cullet 65, red lead 25, nitre 5, arsenic 4, 
 zaffre 1 ; also flint 50, red lead 20, nitre 6, borax 24. Mix equal 
 weights of these frits ; then grind together frit 44, cullet 56. 
 Grind together for printed glaze, frit 40 parts, grauen 25, white 
 lead 25, flint 7, nitre 3 ; and for enamel, substitute litharge 28, 
 without nitre ; and for flat, glaze 45, white lead 45, borax 10. 
 
 9. Frit, grauen 42, flint 10, red lead 25, borax 22, zaffre 1 ; 
 grind frit 73, grauen 18, flint 9 ; then mix, tor printed, glaze 63, 
 white lead 37 ; or, for enamel, glaze 67, litharge 33 ; or, for mocha, 
 glaze 55, litharge 45. 
 
 10. Frit, cullet 68, red lead 20, arsenic 5, nitre 6, zaffre 1 ; 
 grind, and for printed glaze, frit 80, white lead 20. 
 
 11. For flat, frit flint 50, red lead 16, borax 25, nitre 8, 
 -zaffre 1 ; grind, for printed, mix frit 75, white lead 25. 
 
 12. Frit, separate, cullet 90, white lead 9, zaffre 1 ; also cullet 
 68, red lead 27, arsenic 5. Grind 20 parts of 1 with 80 of 2 ; or 
 25 with 75 for flat. Of mixed frit, grind 30 with grauen 50, flint 
 20 ; then mix glaze 54, lead 46. 
 
 13. 14. Frit, cullet 60, 57, red lead 15, 18, arsenic 10, borax 
 15, 10, nitre 0, 5. Grind together frit 20, 40, cullet 60, 0, stone 
 15, 48, flint 5, 12 ; then mix glaze 75, 50, white lead 25, 50, for 
 printed ; and for mocha, glaze 70, 60, litharge 30, 40. 
 
 hence is improper for glazes, though useful for enamels. The usual tin-ashes 
 are thus formed : Count Chaptal first suggested their use fritted with silica 1, 
 ashes 2. In an open utensil heat to a low red, lead 100, tin 25, or 30, or 
 lead 100, tin 110, and skim quickly till no more be formed, and preserve any 
 residue ; then the skum (or oxide) reheat till no longer inflammable, and the 
 whole is of a grey colour. For oxide of tin may be substituted with advantage 
 the very fine powder of calcined native phosphate of lime (or, in its absence, 
 the earth of bone, carefully picked before being ground, and then calcined), 
 being invitrescible, and very white. 
 
480 
 
 CHEMISTRY OF POTTERY. 
 
 The following are in the precise form communi 
 cated : 
 
 William Moore. 
 
 Fritted. 
 
 Frit CuUet 20 Ib. 
 
 White Lead 2 
 
 Common Salt 1 
 
 Arsenic J 
 
 Blue Calc.., i oz. 
 
 Grind with White Lead 
 
 C. Stone 
 
 Frit 
 
 Flint 
 
 Borax.. 
 
 52 
 28 
 12 
 15 
 6 
 
 Grind together 
 
 White Lead 56 
 
 CornwaU Stone 28 
 
 Flint 14 
 
 CuUet... 12 
 
 Without Frit. 
 
 Add 
 
 B. Calc 1 oz. 
 
 Flow with Potash 8 
 
 or 
 Salt Rock.. 4 
 
 John Barlow. 
 Frit separately 
 
 Gullet 34 
 
 W. Lead.... 4 
 Com. Salt... 2 
 Nitre... 1 
 
 Grind together with 
 Flint.... 30 W. Lead.... 113 Ib. 
 Borax... 6 C. Stone.... 53 
 Soda.. 3 Stain... 5* 
 
 * W. lead 4, nitre 1, salt 2, cullet 60, borax 2, B. calc 20. 
 
 John Clowes. 
 
 Cullet 
 
 Red Lead, 
 
 Nitre 
 
 Salt... 
 
 Frit separately 
 
 (1) (2) 
 
 44 32 
 
 4 4 
 
 1 1 
 
 2 1 
 
 Grind (1) together with 
 
 White Lead 117 
 
 Cornwall Stone 57 
 
 Cullet 25 
 
 Borax 6 
 
 (1) (2) 
 
 4 4 Borax. 
 24 18 Flint. 
 1 Soda. 
 
 1 2 oz. B. Calc. 
 
 (2) 
 156 
 
 72 
 36 
 
 12 
 
GLAZES.' 481 
 
 The preceding are immediately in dates prior to 
 the two following, which are employed more generally 
 than any previously compounded ; and by their intro- 
 duction, the different tints of beautiful colours have 
 become useful, with which no other glaze could be 
 with confidence employed. The employment of lime 
 with boracic acid and soda,, and borax, accomplishes 
 the vast difference. 
 
 (1) (2) Glaze. 
 
 Frit Grauen 100 or 120 100 Ibs. of Frit 1, grind with 
 
 Borax (or 60 80 25 White lead ; and of No. 2, 
 
 Tincal 80) (100) \vith30Whitelead. 
 
 Flint 50 50 
 
 Soda 20 
 
 Whiting* ... 20 25 
 
 * These salts are incompatible with each other, and will combine in only 
 extremely minute proportions in water at the regular temperature ; conse- 
 quently, whenever any of them results from the components of the glaze, there 
 is every reason to fear crazing. 
 
 Salt. Incompatible with 
 
 Muriate of Barytes Carbonated alkalies, earthy carbonates, and sulphates. 
 Sulphate of Lime Alkalies, carbonate of magnesia, and muriate of barytes. 
 
 Nitrate of Lime Carbonated alkalies, carbonate of magnesia, and of 
 
 alumine, sulphates (except of lime). 
 Muriate of Lime Carbonated alkalies, earthy carbonates, and sulphates 
 
 (except of lime). 
 Sulphate of Magnesia Alkalies, muriate of barytes, nitrate and muriate of 
 
 lime. 
 
 Muriate of Magnesia Carbonated and sulphated alkalies. 
 Alum (Potash Sul- Alkalies, muriate of barytes, nitrate and muriate of 
 
 phate of Alumine) lime, carbonate of lime, and of magnesia. 
 Sulphate of Iron Alkalies, muriate of barytes, and earthy carbonates. 
 
 Fixed Sulpd. Alkalies Nitrate and muriate of lime and of magnesia. 
 
 2 i 
 
482 CHEMISTRY OF POTTERY. 
 
 ANALYSIS OF FRIT. 
 
 We assume that the frit has lead, silica, alkali, 
 and colorific oxides present, which we wish to deter- 
 mine, a. Of the frit, whether glaze or colour, in 
 fine powder, take 10 grains, and in aqua regia (2 N A 
 and 1 M A), 50 grains, carefully boil about 80 
 ! minutes ; add ten bulks of boiling pure water, filter, 
 wash with warm water, dry the filter ; and its con- 
 tents with thrice the weight of caustic potass, fuse 
 in a porcelain or silver (not platinum) crucible ; 
 when cool, pulverise and dissolve in muriatic acid, 
 add much pure water, and slowly evaporate dry. 
 The residuum again dissolve in muriatic acid, and 
 add plenty of water ; repose 24 hours, and then filter 
 out, wash well, incandesce, and weigh the silica 
 precipitated. />. The filtered liquid slowly evaporate 
 dry, again add plenty of pure water, mix well, and 
 after 48 hours' repose, filter out and treat, as just 
 directed, the remaining silica. c. The liquid left 
 from the filter alkalinise with ammonia till no more 
 be appropriated ; repose 24 hours, then filter out and 
 wash well the oxides precipitated, and lay aside for 
 process / d. To the liquid from the last filtering 
 add the solution of oxalic acid till aciduline ; allow 
 12 hours for repose, then filter out, incandesce, and 
 weigh the lime obtained, e. Next acidulate the 
 liquid with muriatic acid, and by slow evaporation 
 obtain the muriate of soda. / In muriatic acid boil 
 the precipitate, c, 80 minutes, add plenty of warm 
 water, and by the proper tests determine which 
 oxides are present, and then obtain them by the usual 
 methods. (See pages 115-119.) 
 
GLAZES. 483 
 
 ANALYSIS OF GLAZE. 
 
 WE may suppose that the glaze has present 
 lead, xoda, lime, boracic acid, alumine and silica. 
 ((. In muriatic acid separate the substance, and when 
 all is appropriated by the acid, raise the temperature 
 to 140 Fahrenheit, and continue till all the liquid 
 is evaporated ; next moisten the residuum with con- 
 centrated muriatic acid, add fifteen bulks of distilled 
 water ; allow to repose 24 hours, decant off the liquid, 
 and throw on a filter the silica deposited, which wash 
 well, and treat as directed in page 141. b. To the 
 filtered liquid add test 2 (caustic ammonia), and after 
 12 hours' repose, filter out the precipitated alumine. 
 c. The liquid treat with oxalate of ammonia, raise the 
 temperature, let it repose 12 hours, then filter out the 
 lime. The liquid yet contains lead, boracic acid, 
 soda and sal ammoniac. By processes, 2, c. (p. 126), 
 and 2, b, (p. 130), determine the presence and quan- 
 tity, or proportion of the two former, lead and acid ; 
 and then, to find the soda, d, again completely eva- 
 porate the liquid, and keep at a raised temperature 
 till all the sal ammoniac is dissipated, without fusing 
 the soda. Were magnesia present, washing would 
 dissolve the alkali and leave the earth deposited. 
 
 To separate any potash, or lithia, or both, when 
 present with the soda : To the salt left (d\ 6 parts, 
 add 94 of chloro-platinate of sodium, and the potas- 
 sium, when alone present, will exchange condition 
 with the sodium in the double salt. Add plenty of 
 warm pure water, gently evaporate dry ; by alcohol 
 
 appropriate the chloride of sodium, and the excess of 
 
 2 i 2 
 
484 CHEMISTRY OF POTTERY. 
 
 the chloro-platinate of sodium. The chloro-platinate 
 of potassium wash with alcohol, dry, weigh, and 100 
 of the salt will have present 3073 chloride of potas- 
 sium. The weight must be deducted from that of the 
 saline mixture used, and thereby is determined the 
 quantity of the chloride of sodium. For the lithia, 
 add phosphoric acid, and phosphate of soda in ex- 
 cess ; evaporate dry, add plenty of cold water, eva- 
 porate dry, incandesce and weigh, and 100 of the 
 salt will have present 15 '08 lithia. The weight of 
 the chloride will supply the quantity of the alkalies 
 together, and of each separately. When the tests 
 for potash and lithia are indifferent, the presence 
 of soda is inferred. 
 
 The following are genuine recipes of the parties 
 whose names they bear : 
 
 John Hancock. 
 
 Body. Frit. Glaze. 
 
 C. Stone.... 140 Ibs. 30 Ibs. ... 30 Frit Grind with 
 
 China clay . 120 10 Glass 24 White lead 
 
 Flint 100 4J ... 36 60 Ibs. 
 
 Blue Calc 2 or 3 oz. Blue clay 20 Nitre 4 oz. 
 
 Aaron Hancock. 
 
 Body. Glaze. 
 
 Cornwall Stone 50 60 Frit Cornwall Stone 42, Gullet 49, 
 
 China clay 10 20 White Enamel 7 (Gullet 16, Bed 
 
 Blue ditto 30 30 Lead 5, Borax 1, Arsenic 1, fused 
 
 Black ditto 20 16 together 6 hours), Pearlash 2, Nitre 
 
 Cracking ditto . 20 16 1, Blue Calc 1 J oz. ; and this charge 
 
 Flint 20 30 grind with 56 Ibs. White Lead. 
 
GLAZES. 
 
 485 
 
 William Whieldon. 
 
 Body. 
 
 Cornwall Stone 200 120 
 
 China clay 100 80 
 
 Blue ditto 100 120 
 
 Black ditto 80 50 
 
 Flint 150 80 
 
 Blue Calc .. 4 oz. 2 or 3 oz. 
 
 Blue Frits. 
 
 Cullet 26 
 
 Litharge 7 
 
 Nitre... 3 
 
 Glaze. 
 
 Grind together 
 
 23 Frit 100 
 
 16 Stone. White Lead 75 
 
 15 Flint. or 
 
 Arsenic 1J 15 Borax. 
 
 B. Calc... 6 oz. 8 oz. 
 
 Frit 
 
 120 
 
 White Lead 95 
 
 Flow with 12 oz. Pearlash, and 1 oz. Bay Salt. 
 
 Frit 
 
 Bone .... 
 C. Stone 
 C. Clay. 
 Blue do. 
 
 Charles Penny. 
 
 Body. Glaze. 
 
 Frit 
 
 40 C. Stone.... 40 
 
 160 150 Soda... 10 
 
 80 
 80 
 16 
 
 100 
 80 
 20 
 
 Grind together 
 
 Frit 80 
 
 C. Stone 30 
 
 Flint 40 
 
 W. Lead 65 
 
 Borax... 20 
 
 Stain with Blue Calc. 
 
 William Handley. 
 Body. 
 
 Frit- 
 
 Glaze. 
 
 Grind together 
 
 Bone 
 
 170 220 
 
 C. Stone.... 
 
 50 
 
 30 
 
 Frit 80 
 
 C. Clay.... 
 
 105 60 
 
 Cullet 
 
 60 
 
 30 
 
 W. Lead 20 
 
 Blue ditto. 
 Felspar.... 
 
 30 160 
 95 120 
 
 Eed Lead .. 
 Borax . ... 
 
 20 
 50 
 
 10 
 
 20 
 
 or 
 Frit 40 
 
 Blue Calc. 
 
 4 oz. 6 oz. 
 
 Nitre 
 
 6 
 
 6 
 
 W. Lead 40 
 
 
 
 
 
 
 Cullet..., 20 
 
486 CHEMISTKY OF POTTEKY. 
 
 George Jones. 
 
 Body. 
 
 Cornwall Stone 120 120 
 
 Bone 88 80 
 
 C. Clay 56 25 
 
 Blue ditto 24 50 
 
 Flint 20 16 
 
 Blue Calc 4 oz. 4 oz. 
 
 Glaze. 
 
 Frit Grind together 
 
 Gullet 20 15 Frit 10 30 
 
 Bed Lead 20 10 CuUet 4 20 
 
 Flint 60 20 W. Lead.. 6 30 
 
 Arsenic 1 6 Nitre. Flint 1 
 
 Borax . . 40 10 
 
 The semifluid glaze must have only that con- 
 sistence or specific weight per ale pint, which will be 
 in precise accordance with supplying a coating to the 
 biscuit agreeably to its pyrometrical expansibility and 
 peculiar components. The cream-colour glaze must 
 be opaque, clear, free from specks, much like velvet, 
 and indifferent to the soliciting of acid and alkali, 
 and to alternation of temperature. In raw glazes, or 
 those whose components are mixed without previous 
 preparation, there is considerable care needed to pre- 
 vent, in the dipping-tub, the metallic oxides preci- 
 pitating, because of their specific gravity ; whereby, 
 instead of the useful components remaining suspended, 
 merely an aqueous mixture of earthy components is 
 present, inadequate to supply a suitable proportion of 
 materials to cover the biscuit. Continued agitation 
 does not always avail, and the employment si & flow 
 of common salt may produce a yellow tint prejudicial 
 
GLAZES. 487 
 
 to the ware; and in the fritted glazes, the use of spirit 
 of salt, or muriatic acid, cannot be otherwise than 
 injudicious, and should be superseded (may I ask 
 whether raised temperature would not answer ?); for 
 when the baking process dissipates the acid, its gas 
 carries away with it whatever it had previously 
 solicited to combination. 
 
 Soda, or Barilla-ashes, in the state of carbonate, 
 is the alkali generally used to promote the vitrifica- 
 tion of the earths and metallic oxides as silicates, 
 because, by its greater potency in combining with 
 silica, it forms a thinner glaze, and is cheaper than 
 potash. For other uses, its sophistication by neutral 
 salts and alkaline earths would depreciate its value ; 
 but as these generally promote vitrescence, its utility 
 for potters is scarcely affected. The carbonic acid 
 dissipates in the oven, and all the substances fuse 
 together into a silicious mass, the soda as a pure (not 
 carbonated) alkali combines with the silica, and the 
 glaze. is equally with glass durable when cold.* 
 
 * The following notices were overlaid when page 220 was 
 printed, else they would have appeared there : 
 
 Natron, native sesquicarbonate of soda, is found at the foot of 
 a mountain in the province of Suckena, a subject-state of Tripoli, 
 from which city it is twenty-eight days' journey, and two from 
 Fezzan, in Africa. It has a varied thickness from an inch to a 
 line, and occurs in crystals formed into prisms, fibrous masses, 
 and congeries of crystals. It has translucence, vitreous glistening 
 lustre, grey or yellowish-white colour, mild alkaline savour, is 
 soluble in water, but indifferent to the action of the air. 
 
 Tincal is found in Thibet, China, Ceylon, Tartary, Saxony, 
 Transylvania, and Potosi. That from Thibet is supplied by an 
 extensive lake, fifteen days' journey from Tisoolumbo, the capital 
 of the country. The situation is elevated, and most of the year the 
 
488 CHEMISTRY OF POTTERY. 
 
 But Borax is unrivalled in its property of pro- 
 moting the fusibility of vitrifiable components, 
 causing the compound to flow most freely, without 
 
 springs are frozen, and deposit on the edges and shallows both 
 borate and muriate of soda (tincal and common salt). The deposit 
 leaves holes that are refilled, and again emptied as needed. 
 
 A Nitrate of Soda (with some impurities of nitre, salt, clay, 
 and sand) has recently been introduced into the market from 
 Tarapaca in Chili. Its properties are not yet determined, but its 
 crystallisation and efflorescence indicate some mode of preparation. 
 
 The material named Lynn Sand is of a very fine quartzose 
 nature, supplied from the small port Lynn, on the coast of Norfolk, 
 and a similar kind is supplied from Alum Bay, the .western 
 extremity of the Isle of Wight. Its use commenced and continues 
 (whether calcined to separate all carbonaceous impurities, or 
 merely washed to remove soluble ingredients), because it is an 
 excellent substitute for flint, saving the expenses attached, and 
 the small portion of alkali which remains assists in its vitrification. 
 
 Arsenic is a very powerful fiux in promoting complete vitrifi- 
 cation, and with this advantage, that whatever carbonaceous 
 particles it may be in contact with, it volatilises likewise with 
 them during the fixation of the oxygen. It is very useful in the 
 dipped ware for aiding the manganese. Nitre also dissipates any 
 carbonaceous ingredients with which it has been in contact 
 previous to fusion. 
 
 Lead, even at a low quotation, is dear for glaze, and the only 
 reason for its continued use is the knowledge of its application. 
 It renders the glaze heavy, fusible, soft, and easily injured by acid 
 and alkali when heated. The proportions of the oxides introduced 
 into the frit, as well as mixed with it after grinding, must be so 
 carefully adapted to the whole quantity of components, also to com- 
 plete intermixture with those which are alkaline, that pernicious 
 results may not ensue from their adoption. The red oxide pro- 
 motes the vitrification, at a low temperature, of all the components, 
 and increases the density without impairing the lustre of the glaze. 
 Litharge, however, will answer in smaller proportions than red or 
 white lead, as 86 to 116 and 126. It will per se fuse into a clear 
 transparent dense glass, remarkably soft and velvety to the touch, 
 
GLAZES. 489 
 
 Bubbles or specks, and thus increasing the beauty of 
 the glaze. It has not yet been solved how mnch of 
 the boracic acid is evolved during the glaze-baking, 
 and it needs careful adaptation for colours formed 
 of nitro-muriates. With alumine it slowly forms a 
 permanent glass, opaque with excess of the earth. 
 And as the fineness of tint, from a solution of cobalt, 
 improves by its purity, there seems a proof that in 
 proportion to the excellence of the materials which 
 composed the body will be the beauty of the Blue 
 Printed Ware. The transferring process causes a 
 mechanical, and the glaze-baking a chemical com- 
 bination of the silica, alumine and cobalt. 
 
 As a substitute for borax, some employ equal 
 weights of nitre and flowers of sulphur, incandesced, 
 till all sulphurous acid has evolved, when the sulpho- 
 nitrate of potash is poured upon an iron plate, and 
 when cool, the scum is carefully separated from the 
 chemical compound. 
 
 and fusible at a low red heal When the temperature is very high, 
 unless earths are present, this oxide will permeate and escape 
 through common crucibles almost like liquid through a sieve, and 
 corrode the vessel. In forming a glaze, both red and white lead 
 form litharge, by the high temperature of the baking process dis- 
 sipating the oxygen of the former, and the carbonic acid of the 
 latter, and their value must have the ratio of their respective 
 numbers for them to be equally cheap. 
 
490 CHEMISTRY OF POTTEEY. 
 
 COLOURED GLAZES, DIPS, AND SMEARS. 
 
 THE following are the components of the best in 
 present use : 
 
 COLOURED GLAZES. 
 
 Black. 1. Frit together and grind for use, black oxides of 
 copper, manganese, and iron, and oxide of cobalt, equal parts, with 
 2 parts nitre and 20 cullet. For inside, white lead 80, flint 16, 
 manganese 4. 2, 3. In clean water mix manganese 8, 4, ochre 46, 
 12, blue clay 46, 84 ; pass through the lawn for use. 
 
 Ditto. (Shining.) I. To flinted slip (4) 60 parts, add red 
 lead 40 ; of this liquid 86 parts intermix with 14 manganese. 
 2. White lead 66, manganese 24, flint 10, mix together for use. 
 
 Brown. In slip 3, 33 parts, mix red lead 62 parts and flint 5 
 (and for black, add 2 parts manganese). 2. Glaze 5, 33 parts, 
 and frit glaze 3, 67 parts. 3. For jug necks, use 67 and 33. 
 
 Yellow. 1. In cream-colour glaze 4, 72 parts, mix base 
 yellow 14, and litharge 14 parts. 2. Glaze 1, 80 parts, biscuit 
 yellow 20. 
 
 Green. Frit together and grind for use, white lead 54 parts, 
 flint 27, blue clay 9, oxide of copper 9, cobalt calc 2, or 1, or sul- 
 phate of copper 60, flint 20, cullet 20; grind with litharge 35, 
 flint 27, grauen 16, frit 14. Mix frit 15 parts, glaze 6, 85 parts ; 
 or 40 and 60 for edging. 3. Frit lead 33, copper calc 28, flint 22, 
 cullet 17 ; grind and mix frit 20 parts, printing glaze 4, 80 parts, 
 or for dessert- ware, frit 24, glaze 76; or glaze 4, 80 parts, oxide 
 of copper 20. 
 
 DIPS. 
 
 Brown. 1. Mix best ware shavings into slip 24 oz. to pint, 
 then to slip 80 parts, add ochre 13, manganese 7, and bake in the 
 first ring. 2. Calcine ball clay, brick clay, ochre, and Bradwall 
 red clay, equal parts ; pass through 14 lawn, then to 92 of liquid 
 add 8 of oxide of nickel. 3. (Mingled.) Best shavings slip 75, 
 ground per oxide of iron 25. Bake as above (or 4, brick clay 97, 
 zaffre 3, bake in second ring). 4, 5, 6. (Purple.) Brown dip 1, 
 80, 48, Ironstone 20, 5, Manganese 0, 48. 7. Best ware shavings. 
 
GLAZES,, 491 
 
 slip 34, brown dip 56, ochre 8, manganese 2. 8, the last, with 
 ochre 4, Spanish brown 4, for china jugs. 
 
 Blue. I and 2. Blue clay 28, 23, grauen 50, 27, flint 0, 27, 
 plaster 20, 0, China clay 0, 15, blue calc 2, 8 ; through 14 lawn. 
 
 Grey. Best shavings slip 94, blue calc 6 ; or 75, flint 15, 
 emery 6, manganese 4 ; grind well for use. 
 
 Green. 1. Best slip 96, blue calc 3, copper calc 1. 2. Or, 
 (mingled) calcine well ball clay 75, blue calc 25 ; and to 20 of 
 this add 80 best slip. 3. Stone body slip 94, and zaffre 6 parts. 
 4. Black marie slip 92, blue calc 8. 5. Cane dip 96, blue calc 4. 
 The three last are dark and olive. 
 
 Cane. Equal quantities of best slip and orange dip. 
 
 Orange. Equal quantities of brown dip and black marie. 
 
 Red. Calcine, and grind for use, brick clay 60, Bradwall 
 do. 40. 
 
 SMEARS. 
 
 In hot water mix well salt rock 24, 33, 59, 34, 54, potash 60, 
 45, 9, 48, 42, nitre 18, 22, 32, 18, 14. And to cream-colour 
 glaze 80, add 20 of the smear, for the seggars ; or 86 and 14, 
 90 and 10. 
 
 WASHES. 
 
 For Seggars. In water 2 gallons slake 2 Ibs. of quick-lime ; to 
 lime-water 5 quarts, add common slip without flint 1 quart ; some 
 persons add 10 oz. of salt and 6 of potash. 
 
 For glaze- baking the former ; or, lime 6, slip 1, cream-colour 
 glaze 6 ; lead 4, grauen 1 ; and for bottom, outside, add litharge 5, 
 flint 1. 
 
 To prepare Barytes for using in Glaze. 
 
 Take a seggar of the size adapted to contain the quantity needed ; 
 line this one inch thick with powdered charcoal, put in the sul- 
 phate of barytes, cover well with charcoal, put on a hiller (cover), 
 and lute down well with wad clay ; place the whole at the top or 
 inside of the mouths of the oven as soon as the firing up is com- 
 pleted. At a white heat the sulphuret fuses, and is then to be cast 
 into a strong vessel of boiling- water, which must be drawn off by 
 siphon, and its crystals will be ready for further employment ; 
 and the water itself mav also be used when cleared of charcoal. 
 
492 CHEMISTRY OF POTTERY. 
 
 In GRINDING these mixtures for the different 
 compounds, whether bodies, glazes, or colours, an 
 indispensable condition of the active power is the 
 extension of the arms over the radius of the pan, to 
 constantly rake up or agitate the substance imme- 
 diately after being affected by the runner, that new 
 surfaces may be presented for grinding on each re- 
 volution. That portion of the runner nighest the 
 centre describes a circle with least radius, and each 
 portion enlarges the circle in proportion to distance 
 from the centre ; yet all parts of the runner describe 
 their respective circles in the same period, thus vary- 
 ing the force of abrasion by the slower or quicker 
 motion of the runner over the paver, which arrange- 
 ment is requisite to form impalpable powders. In 
 dry grinding it constantly undermines, breaks, and 
 causes to deposit whatever portion of the substance 
 may have caked up against the sides of the pan ; for 
 when a certain state of comminution is attained, the 
 pressure consolidates the mass and retards abrasion. 
 In semi-fluid grinding the like arrangement to dis- 
 turb the materials that they may not set (or techni- 
 cally suck) is further aided by the introduction of 
 water in which quick-lime is present ; water satu- 
 rated with common salt ; water saturated with equal 
 proportions of sulphates of zinc and iron ; dilute 
 solution of sulphuric or , muriatic acid. For blue 
 and chrome green, a very useful preventive is a 
 crystal of gypsum (or of barytes), in size determined 
 by the quantity of colour under the process. 
 
[ 493 ] 
 
 GLASSES. 
 
 MANY researches of science needing articles of this Manu- 
 facture, attention has been given to improve it every way, so 
 that its fabrications, in beauty and refulgence of substance, 
 and in variety, splendour, and elegance of figure, greatly 
 excel those of the countries whence the Art was originally 
 introduced, to increase the conveniences and comforts of 
 life. As cut forms, of varied sizes and facets, thereby we 
 promote the beautiful prismatic combinations with lustres 
 and chandeliers ; as plates for mirrors we assist beauty 
 to render available all the elegancies of the toilette, and 
 we review near objects ; as vessels, to distinguish, by the 
 transparency, the clear or turbid state of the liquid pre- 
 sented for refreshment: and as sheets, while admitting the 
 solar rays for our enjoyment of the day, yet excluding 
 the pelting storm, the ruthless blast, or the inclement 
 frost. 
 
 GLASS, in the scientific application, signifies all com- 
 pounds hard, brittle, vitrified, and often translucent, which 
 result from continued high temperature acting on two or 
 more earths present together, as alumine, barytes, and lime, 
 or silica, barytes, lime, and fluor spar; certain proportions 
 have chemically combined ; and yet the compound has 
 not hitherto been rendered sufficiently tractile to be 
 fabricated into articles of utility. Hence, in popular 
 language, 
 
 GLASS is the translucent vitrified substance formed by 
 continuing many hours at the temperature of 120 Wedg- 
 wood, 16000 Fahrenheit, certain earths and alkali, and 
 metallic oxides ; the kinds are FLINT-GLASS (the crystal of 
 foreigners), used for the most valuable vessels and ornaments 
 (and coloured by certain metallic oxides to imitate natural 
 gems) ; PLATE-GLASS, for looking-glasses and windows, where 
 appearance and protection are preferred to expense ; CROWN- 
 GLASS, or best sheet window-glass, used in most sash-windows, 
 where a tint in the light admitted would be disagreeable to 
 
494 
 
 CHEMISTRY OF POTTERY. 
 
 the vision : BROAD-GLASS, or coarse greenish window-glass, 
 used for common purposes; and BOTTLE-GLASS, coarse 
 common green glass, whose use is well known to almost 
 every person. 
 
 The essential components of Glass are sand and alkali, 
 with the addition of lime, nitre, borax, and oxides of lead, 
 arsenic, and manganese, in some of the kinds. 
 
 The earths alone, when pure, likewise the alkalies, do not 
 vitrify; but because of greater capacity for appropriating 
 and concentrating heat, the latter becomes solvents, or fluxes, 
 of those refractory substances, by causing the compound to 
 vitrify. Hence, when these readily fusible, and those re- 
 fractory substances, are together raised to a very high 
 temperature long continued, certain proportions chemically 
 combine, the adventitious substances are separated, the 
 melted mass assumes the viscidity of molasses, or bird-lime, 
 and from it the artisan takes whatever portion he may 
 require to form the article needed, and which, passing 
 through the Her in annealing, has its temperature gradually 
 reduced to that of the atmosphere. 
 
 FLINT-GLASS (so named because at first the silicious 
 component was the powder of calcined flint, quartz, or rock- 
 crystal) is that brilliant, beautiful vitreous transparent 
 compound, fabricated into the finest vessels for the table, 
 and the splendid ornaments of the drawing-room. Some 
 practical men are of opinion that on careful and perfect 
 vitrification of the components depends its excellence, more 
 than on their relative proportions. But wherever loss can 
 be superseded, as in both instances, there is advantage in 
 urging attention to the most minute particulars. The 
 Components are: 
 
 
 1 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 White Sand * (purified) 
 
 52 i 52 
 
 54 
 
 56 
 
 55 
 
 56 
 
 Best Pearl Ashes (do.) 
 
 16 ! 16 
 
 39 
 
 39 
 
 39 
 
 30 
 
 Minium 
 
 30 ' 
 
 9 
 
 40 
 
 
 
 Litharge . . ... 
 
 30 
 
 
 
 43 
 
 49 
 
 Nitre 
 
 2 ; 2 
 
 9 
 
 9 
 
 
 9 
 
 
 
 
 
 
 
 *On a farm i-alled Holly-heath, near to the railway, Crewe, Cheshire, 
 is a bed of this fine sand, from which all oxide of iron has been abstracted 
 by an adjoining bed of peat. The trials made with it (1837) are very 
 excellent. 
 
GLASSES. 495 
 
 The sand is purified by careful washing ; the ashe^ by 
 lixiviation and evaporation of the liquid dry. The lead 
 renders the glass more clear, transparent, refractive, dense, 
 susceptible of very high polish, and indifferent to sudden 
 alternations of temperature, while the additional tenacity 
 adapts it for being easily controlled and fabricated by the 
 artisan. The nitre avails for diminution of lead oxide 
 (whose excess renders the glass very soft), and appro- 
 priates any adventitious earths, as well as corrects the tint 
 caused by manganese. 
 
 The components are carefully mixed, put into the pot, 
 and raised to the temperature needed for their chemical 
 combination, which is known by neither bubbles, vapours, 
 nor other impurities on the surface, but the mass appears 
 pure, colourless, translucent, and vitrified. The salts in- 
 different to silica form a white froth, of glass-gall or 
 sandiver, which is constantly skimmed off, else it would 
 injuriously combine with the earths of the pottery ; the 
 temperature next is lowered, till the mass becomes viscid 
 and tenacious, proper for the manipulations. 
 
 COLOURED GLASSES, or PASTES. Artificial Precious 
 Stones. These require to approach, as nigh as possible, 
 those of Nature, in hardness from the components, clearness 
 from speck or bubble, perfect translucence, and lively 
 splendour of colour. To ensure successful results in this 
 branch, most carefully must be regarded constantly the 
 precise degree and continuance of the temperature, the 
 difference by change of alkali, the purity of the compo/ 
 nents, the preparation and precise state of the metallic 
 oxides, solvent or colorific, and the minute quantity 
 which will communicate the required tint to a determined 
 weight of the white glass. 
 
 They are formed by re-melting, after again rendering- 
 friable by suddenly cooling in water while incandescent, 
 one of these frits : 
 
496 
 
 CHEMISTRY OF POTTERY. 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 7 
 
 8 
 
 9 
 
 1011 
 
 12 
 
 13 
 
 Bone 
 Ash 
 
 Onannp 
 
 White Sand (purified) 30 
 Minium 
 
 25 
 
 25 
 
 50 
 
 30 
 
 4S 
 
 35 30 
 5260 
 
 14 
 42 
 
 17 
 50 
 
 26 
 68 
 
 27 
 64 
 
 55 
 9 
 
 52 
 6 
 
 Litharge 48 
 
 Arsenic 4 
 
 
 
 
 
 i 
 
 
 
 
 
 
 7 
 
 7 
 2fl 
 
 Ceruse... .. . 
 
 57 
 
 1-2 
 
 G 
 
 12 
 13 
 
 18 
 52 
 
 C 
 
 26 
 20 
 
 3 5 
 10 
 3 5 
 
 2 
 42 
 
 1 
 32 
 
 4 
 
 7 
 
 3 
 6 
 
 36 
 
 Potash (carb.) ... 
 
 Ditto calcined 
 
 Borax ditto 9 
 
 Nitre ditto... J 9 
 
 The above White Glasses, treated with 1 to 1-5 per cent, of colorific 
 oxide, readily take any required tint of purple and violet by oxide of gold, 
 red by manganese and by iron (which also supplies tints of green, blue, 
 and black), hyacinth by tin, yellow by silver, bismuth, and lead, blue 
 by cobalt, and green by nickel. 
 
 Artificial Garnet. Glass (No. 3) 66, Glass of Antimony 33, Purple 
 of Cassius -5, Oxide of Manganese '5. Or (best prepared in a platinum 
 or plumbago crucible, because of often permeating porcelain), Powder of 
 Rock-crystal 26, Minium 73, Zaffre -2, Oxide of Manganese -8, fritted 
 and re -in el ted. 
 
 Artificial Emerald Glass (No. 2) 98, oxide of copper 1'8, oxide of 
 iron -2. Or, Glass (No. 7) 95, copper 4, iron 1. Or, 92, 7, 1. 
 
 Artificial Amethyst. Glass (No. 5) 96, Nitre 3, Manganese 1, Purple 
 spice. 
 
 Artificial Sapphire. Glass (No. 1) 98, Zaffre 1-8, Manganese '2. Or 
 Silica 35, Soda 18-5, Minium 45, Zaffre 1, Manganese -5, fritted and 
 re-melted. 
 
 Artificial Opal. Glass (Nd. 3) 88-4, Bone Ash 8, Muriate of Silver 
 3, and Magnetic Iron Ore -6. 
 
 Wiegleb recommends for a White Glass, a frit of Silica 31, Alu- 
 mine 31, Magnesia 31, fluate of lime 7, in place of sand, or powder of 
 nints. Mix frit 50, Ceruse 6, borax 19, purified potash 25, or as Glass 
 No. 5. 
 
 Manganese only supplies a red tint to glass, entirely 
 free from impurities and arsenic, and with iron produces 
 a black glass. Its potency in combining with earths cor- 
 rects the colorific effects of impure materials, during 
 complete vitrification, added in proportion to the strength 
 of the tint. When excess has been used, a strong stick is 
 forced through the melted mass, and supplies carbon ; the 
 carbonic acid evolves and produces intumescence, during 
 which the tint disappears, and the glass becomes clear and 
 transparent. The like result ensues on forcing to the 
 bottom and agitating in the mass small lumps of arsenic, 
 
GLASSES. 
 
 497 
 
 which also promote the combination of the components, 
 the due proportion remains inseparable by any usual pro- 
 cesses, and the other volatilises with any carbon present. 
 When a portion remains present, not intimately combined, 
 the glass has a wavy hue, gradually darkens, and decompo- 
 sition progresses, till the articles entirely fail. In fabrica- 
 ting white glass, for the optician's use, great care must 
 be exercised to prevent strata of different densities and 
 refractiveness being formed by the deposit of the oxides 
 in the pot, which also vitrifies the surface in contact. When 
 carbonate of copper, prepared from the sulphate, or the CBS- 
 ustum, is used with Glass No. 1, a fine green is produced; 
 and when the red oxide is used, carmine results. Glass 
 No. 5, 96, Copper 1, and Iron 3, supply a deep red, and 
 this varies with the altered proportions of the oxides. Both 
 chrome and cobalt are indifferent to temperature, and also 
 to the kind of glass ; a green resulting from the former, and 
 the latter alone supplies a rich blue ; with manganese and 
 iron, black ; and with lead and antimony a beautiful green. 
 (See CHAP. IV. COLOURS.) 
 
 PLATE-GLASS is now in request, because more durable 
 and discoloured than the crown or sheet-glass properties 
 of greater value than its increased expense. 'Its components 
 are : 
 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 
 White Sand 
 
 88 
 
 88 
 
 48 
 
 Rfi 
 
 48 
 
 
 Carbonate of Lime. 
 Powder of Quick Lime 
 Soda purified 
 
 5 
 
 17 
 
 5 
 
 18 
 
 ^i 
 26 
 
 3 
 *>4 
 
 4 
 
 27 
 
 
 Gullet (of plates) 
 
 39 
 
 38 
 
 25 
 
 36 
 
 24 
 
 
 Manganese 
 
 1 
 
 1 
 
 
 1 
 
 1 
 
 
 Nitre 
 
 
 
 2 
 
 
 1 
 
 
 Cobalt (a spice)... 
 
 
 
 
 
 
 
 
 
 
 
 The sand is the sharp grained which will pass (with the 
 portion almost impalpable) through a fine wire-cloth sieve ; 
 the agitation mixes these, and supersedes the inconvenient 
 clotting when only the latter is used ; by intimately mixing 
 with the alkali, ready combination by fusion ensues ; and 
 also it separates impurities and the coarse sand, whose 
 fusion would require extra time and fuel. The soda is 
 
 2 K 
 
498 
 
 CHEMISTEY OF POTTERY. 
 
 preferred, because, when moderately pure (prepared by 
 decomposing common 'salt, or lixiviating and evaporating 
 barilla), it increases the fluidity of the melted mass, which 
 readily is spread over a flat surface ; and during the rise 
 of the sandiver, the acids combined are by the high 
 temperature dissipated more readily than when potash is 
 employed.* 
 
 The lime ensures brilliance, clearness, durability and 
 solidity, used in the proportion of not less than 4, nor more 
 than 9 per cent., as chalk or powder; the carbonic acid 
 causes intumescence, which must be carefully noticed to pre- 
 clude losses ; and a larger dose than the above combines with 
 .and injures the interior surface of the pots, diminishing the 
 permeability of heat proportionately with increased vitrifica- 
 tion. When attention is duly paid to this, the quality of the 
 limestone will be of minor importance as of Gibraltar, 
 St. Vincent's near Bristol, Walsall, Dudley, Caldow Low, 
 and Wales. The cullet is prepared by being cast, while 
 incandescent, into cold water. The presence of tint is 
 superseded by the incorporation of the blue of cobalt, the 
 red of manganese, and the light yellow of the soda and 
 silica. 
 
 CROWN-GLASS. This, because without a metallic 
 oxide as a solvent, is harder than flint-glass; and to be 
 fabricated into vessels for like purposes, would require 
 great trouble and patience of the artisan and additional 
 expense of the Manufacturer. The components are : 
 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 7 
 
 8 
 
 
 White Sand 
 
 40 
 
 60 
 
 37 
 
 50 
 
 59 
 
 60 i 58 
 
 64 
 
 
 Carbonate of Lime 
 
 o 
 
 
 
 3 
 
 5 
 
 1 14 
 
 1 
 
 Nitre 
 
 Powder of Quick Lime 
 Carbonate of Soda .. 
 
 18 
 
 3 
 
 4 
 
 17 
 
 
 9 
 
 30 ! 
 
 8 
 27 
 
 1 ^ P ' 
 
 Cullet of sheets .... 
 
 40 
 
 5 
 
 37 
 
 30 
 
 12 
 
 
 
 1 Soda 
 
 n i A. 
 
 Pearl Ashes (*purified) 
 
 
 32* 
 
 22* 
 
 
 24 
 
 | 28* 
 
 
 
 Salt 
 
 About 1 per cent, of charcoal appropriates the sulphuric 
 acid, and precludes not only the loss by intumescence, but 
 
 *Yet I ain disposed to .think that borate of barytes will render 
 equally fluid the silica and potash (as has been asserted of borax), as 
 lime renders the silica and soda. 
 
GLASSES. 499 
 
 also the annoying sulphurous odour. In proportion to the 
 moderate purity of the components will be the absence of 
 tint, and the need of their removal by cobalt and manganese. 
 There often is some iron present with the barilla, or kelp, 
 which causes the deleterious tint. When more cullet is used, 
 the compound is less easily controlled by the artisan, because 
 not sufficiently fluid through diminution of alkali. The 
 temperature is kept at a certain degree, as nigh as possible 
 thirty-five to forty hours. 
 
 BROAD-GLASS, the coarse common kind used for cottage 
 windows, differs from ihe others in components and pro- 
 cesses. The principal component is the soap-boilers' waste, 
 the viscid mass of unappropriated alkali (barilla or kelp), 
 and the lime employed to render caustic what was appropri- 
 ated, with salt and sand, which are well dried, mixed with 
 kelp in these proportions waste 50, kelp 25, sand 25, or 50, 
 20, 30 (dependent on the sand), which, when coarse, requires 
 15 to 20 per cent, more alkali ; by Loysel stated as 50 to 
 100, and 20 to 80 ; then by fritting, prepared for the 
 crucible, into which it is put while incandescent, and 
 during upwards of twelve hours is fused until perfectly 
 vitrified. 
 
 BOTTLE-GLASS. Its composition varies in almost every 
 Manufactory, in which pecularity it much resembles potting. 
 There is constant attention to economy, and consequently it 
 is formed with different quantities of sand, \lime, any cheap 
 alkali, or ashes, marie, and even the slag* of iron-furnaces, 
 which has often much lime present with silica. Need it be 
 
 *In the quarry at Rowley -regis, from which are obtained the 
 materials which repair the highways, is a basaltic earth, which may f>e 
 advantageously used in this branch of the Manufacture ; according to the 
 suggestions of Count Chaptal, M. Ducros, arid the recent experiments of 
 M. Aliot, thus stated : 
 
 " The basaltic earth was decomposed and pulverulent, then put into 
 crucibles, and the heat was that of a potter's oven during 18 hours. 
 
 " No. 1, filled with basaltic earth only, supplied a black opaque glass, 
 moderately vitrified. 
 
 " No. 2, filled with a mixture of equal portions of basalt, quartz, and 
 ashes, supplied a chocolate glass, lustrous and porcelaineous. 
 
 2 K 2 
 
500 CHEMISTKY OF POTTERY. 
 
 stated that hardness will result. Some Manufacturers use 
 25 of sand and lime with 75 of soap-boilers' waste ; others 
 use 30 sand, 10 kelp, and 60 waste. According to Loysel, 
 the components of the French bottles are common sand 
 20 or 22, coarse kelp 8, earth of ashes 30 or 32, wood- 
 ashes 8 or 6, brick-clay 16, and cullet (of bottles) 18 or 
 16, which purifies free from sandiver or glass gall, and 
 during incandescence as frit is transferred to the pot for 
 use. 
 
 Phosphoric Glass (of Bones). Count Chaptal mentions 
 the production of a glass, apparently only another triumph 
 of Art, but not applicable to any useful purpose : Boil well 
 fcound fresh bone; then digest 66 parts in 34 .of sulphuric 
 acid, 63 to 72 hours; evaporate dry, and wash in different 
 portions of pure water, till no discoloration ensues; mix, 
 and evaporate these dry ; the sediment mix in pure water, 
 and filter out the sulphate of lime, which put into a very 
 large crucible, and, when the intumescence subsides, the glass 
 is formed, of a fine milky whiteness.* 
 
 " No. 3, filled with a mixture of equal portions of basalt and sand, 
 supplied a moderately vitrified glass, appearing blue-black, but thin 
 pieces were yellowish-green. 
 
 "No. 4, filled with a mixture of equal portions of sand, refuse soda, 
 and basaltic earth, supplied a good, shining, smooth, greenish-yellow, 
 transparent, and well-vitrified glass, well adapted for bottles. 
 
 " No. 5, filled with only sand, from the river Orb, where much 
 basaltic earth is present, supplied a well-vitrified glass, apparently well 
 adapted for the fabrication of glass bottles." 
 
 When the components of basaltic earth are noticed, silica 48, alumine 
 16, lime 10, oxide of iron 20, and alkali 4, the cause of vitrescence will 
 appear in the solvent nature of three of the components, and the glass 
 produced is indifferent to corrosive liquids, is harder, tougher, and less 
 subject to flee, which properties are estimable in chemical utensils, 
 retorts, phials, etc. 
 
 M. Aliot also formed an excellent bottle-glass, of a yellowish -black 
 tint, interspersed with opaque bluish- white veins, of this mixture : (1) 
 Common sand 62, ashes 32, and soda 6. He also found that (2) Volcanic 
 granite 50, wood-ashes 50, readily vitrified, completely, to a dark lustrous 
 fine glass, well adapted for bottles. 
 
 *The salt, when mixed with charcoal-powder and distilled, produces 
 excellent phosphorus. 
 
GLASSES. 501 
 
 BRITISH SHEET-GLASS. This has the like components 
 and proportions as the best crown-glass ; but this latter has 
 a waviness which frequently much distorts those objects seen 
 through it, from which defect the British sheet-glass is 
 free, as when looked through from the inside the vision is 
 as clear and distinct as when plate is used, although the 
 outer surface seems uneven (cockled}. It is made of 
 different dimensions, from 40 x 30, to 50 x 36 incites 
 surface, as required; and from l-20th to 1-half inch in 
 thickness: but this usually is 1-1 2th, and crown-glass 
 l-16th. The manipulations are like those for broad, 
 common or green-glass. The metal is first formed into 
 cylinders of the proper diameters required ; next these are 
 brought to the mouth of the oven, and the temperature 
 raised, while the end of the iron tube is closed ; the included 
 air rarifies, and expands the cylinder until its weakest part 
 bursts, when instantly the whole surface is opened, 
 carefully smoothed Hat, and removed to be annealed. 
 Messrs. Chance Brothers, Birmingham, are the only 
 Manufacturers of this addition to our trade ; and likewise 
 of the beautiful square, oval and cylindrical SHADES for 
 clocks and choice ornaments, usually obtained from France, 
 at more than double the cost now charged by this enter- 
 prising company. 
 
 Crown-glass is not made in France ; and only of 
 inferior quality, and to a very limited extent in Germany ; 
 yet the German sheet-glass, for windows, is superior to the 
 French and Belgian, both of which excel the British 
 broad-glass. At page 372 I have mentioned the manner 
 in which much sheet-glass is made in Germany for Nurem- 
 berg, where it is polished for exportation. Formerly a 
 considerable traffic in this kind of glass was illicitly carried 
 on from Holland by smugglers, and the best specimens of 
 the engraver's art were protected by Dutch glass. Now, 
 however, instead of being necessitated to obtain sheets from 
 Germany, or surreptitiously from Holland, a superior article 
 for home and foreign consumption is fabricated by our 
 countrymen. 
 
502 CHEMISTRY OF POTTERY. 
 
 One of the Brothers Chance, having business to 
 transact in the French metropolis, indulged in a visit to 
 several of the glass Manufactories in France, Belgium and 
 Germany. Although crown-glass is not made by some of 
 these, and only of inferior quality where it is made, yet in 
 making sheets, the improvements have been progressive in 
 many Manufactories during the last half century. Mr. 
 Chance being very intimately acquainted with the most 
 improved Manipulations of crown-glass making, readily 
 conceived how the improvements of the continental 
 manufacturers might be advantageously employed in the 
 establishment at home; and in 1832 was commenced 
 the fabrication of sheets, surpassing in excellence any 
 previously attempted. Some supercilious party, certainly, 
 may attempt to gainsay any merit for ingenuity or manual 
 dexterity because "it is his trade." Admitted; but we 
 must likewise admit that there have been successfully 
 exerted some mental talent to arrange the suggestions of 
 his inventive powers, some inherent genius to direct the use 
 of his tools in manipulations; and we must claim this 
 as a striking proof of the advantage of possessing as well 
 theoretical knowledge as practical skill, literary information 
 as mechanical ability. Fully aware of the capabilities and 
 intrinsic importance of his Art, and wishful to raise it, and 
 his own character also, the utmost skill and ingenuity of 
 Mr. Chance were exercised to improve the manipulations 
 of his concern, and promote the comforts, and conveniences, 
 and elegancies of life. 
 
 The excellence of glass depends, in addition to the 
 components, on good founding, the quality of the fuel, 
 the management of the furnace, the process of fusion, with 
 general knowledge of the manipulations, acquaintance with 
 chemical science, unremitted attention and skill in directing 
 and controlling the operatives, preserving industry, and 
 studied cleanliness in every department ; and to ensure 
 successful results, the utmost care and skill of a judicious 
 builder, as well as the best and most suitable materials, are 
 indispensable for the furnaces to be erected in a proper and 
 substantial manner. 
 
GLASSES. 503 
 
 Flint-glass, the heaviest, most brilliant, and costly 
 vitreous substance, also much in demand for optical and 
 other philosophical purposes, differs from other kinds, 
 chiefly in a metallic oxide being among its components.* 
 When silica, an alkali, and any metallic oxide are raised 
 to a very high temperature, some time continued, a glass 
 results, but with a tint peculiar to the metal, except only 
 lead and bismuth, with which the mass is bright and 
 colourless ; and even excess of lead causes the metal to be 
 slightly yellowish, and inconveniently soft. The object of 
 greatest importance, and most to be regarded, therefore, is 
 (and the remark applies generally to the subjects of this 
 work), in compounding and founding vitreous substances, 
 to employ and bring together precisely those proportions 
 of the respective components which will exactly appropriate 
 and saturate each other. 
 
 The foreign Crystal, or white glass, is formed of the 
 best white tarso of the Po and carb. potash, in the proportions 
 of 60 and 40. The components are pulverised, then fused, 
 and afterwards raised very high during five hours. This 
 frit is carefully kept. The process of Glass-Making is 
 this : The frit is cast into the pot, and the manganese is 
 added to clarify it entirely ; the fused mass is either laded 
 out into water, thereby to appropriate all the sandiver, or 
 this is carefully and frequently skimmed oft' till the mass is 
 purged. The high temperature is kept up from four to six 
 days, arsenic being occasionally added (for reasons assigned, 
 p. 308), and manganese likewise till the proof shows metal 
 shining and clear. The late Dr. G. Shaw, when mentioning 
 
 * There is recorded in the annals of China that, in A.D. 627, a glass 
 vessel was fabricated at Fokien, and which is still preserved at Pekin, 
 so very large, that to convey it to the Emperor's palace, four cars were 
 used, with upright poles, to which were secured the corners of a large net, 
 into which the vessel was placed ; and that a mule can as readily enter 
 into it as can a fly enter into a pitcher. Yet to the improvement of this 
 art the Chinese government is indifferent, although a Manufactory exists 
 belonging to it, in Pekin, and the porcelain trade receives every degree of 
 patronage. 
 
504 
 
 CHEMISTRY OF POTTERY. 
 
 a crystal similar to No. 2, states that the components were 
 first fused, and then as quickly as possible raised in tempera- 
 ture during half an hour ; the whole was left 24 hours, then 
 the crucible was broken, and at the bottom was a hard glass, 
 capable of cutting common glass, like a diamond. He adds : 
 " This experiment, duly varied, may lead to several useful 
 improvements in making glass enamels and factitious gems, 
 and shows an expeditious method of making glass without 
 any fixed alkali, which has been generally thought an 
 essential ingredient in glass; and perhaps calcined crystal 
 or other substances, added to the borax, in place of sand, 
 might make a glass approaching to the nature of a 
 diamond." 
 
 The article " GLASS" (Ency. Britt., Edit. 1835), gives 
 these proportions of components: Sand 40, Carbonate of 
 Soda 35, Gullet 20, Nitre 2, Lime 2, and Charcoal 1 (or 336, 
 280, 163, 14, 14, 7, in a pot of 814 Ibs.), for an excellent metal 
 for crown-glass, and as it can be blown much thinner, and is 
 finer, it is very economical in materials, fuel, time, wages, 
 and excise duty. 
 
 Sand 
 
 1 
 
 2 
 
 Ci 
 
 8 
 
 vst 
 '4 
 
 al 
 
 5 
 
 >r 
 (3 
 
 ^'lii 
 
 7 
 
 it. 
 8 
 
 9 
 
 10 
 
 Sh( 
 1 
 
 56 
 
 23-5 
 14 
 6-5 
 
 et. 
 2 
 
 66 
 
 22 
 8 
 1-2 
 2-8 
 
 Cro 
 
 1 
 
 57 
 
 28 
 14 
 1 
 
 * 
 
 wn. 
 2 
 
 Coi 
 1 
 
 60 
 
 28 
 
 2 
 
 10 
 
 * 
 
 nn. 
 2 
 
 (t)or 
 Soda 
 
 [ashes. 
 Wood 
 
 59 
 
 34 
 5 
 ,2 
 
 30 
 
 70 
 
 50 
 22 
 18 
 9 
 
 1 
 
 54 
 1(3 
 25 
 5 
 
 (30 
 20 
 17 
 
 8 
 
 (50 
 15 
 10 
 5 
 
 8 
 7 
 
 (50 
 
 35 
 5 
 
 
 
 04 
 2(3 
 
 6 
 
 4 
 
 
 
 59 
 
 25 
 5 
 
 2 
 
 10 
 
 * 
 
 52 
 
 13 
 
 2 
 
 8 
 25 
 
 Minium 
 Potash (carb.) 
 Nitre 
 
 Borax 
 
 Arsenic 
 Salt (table) 
 Manganese 
 
 * 
 
 
 
 
 
 
 
 The following are in addition to those previously given : 
 
 The reference is to Glass No. 1. Balass colour. Fuse 
 crystal frit, adding red oxide of manganese ; the mass will 
 become clear purple ; add the carb. potash gradually to 
 dissipate the manganese. 
 
 Black. Gullets, of different colours, fuse, and add 
 a mixture of zaffre 2 and manganese 1, to supply the 
 colour. 
 
 Or crystal, pulverised, 45, and pulverine 45, lead and 
 tin ashes 8, steel scales 1, and iron ditto 1, raise the 
 temperature very high 12 hours. 
 
GLASSES. 505 
 
 Or crystal frit 92, when fused, gradually add tar- 
 trate of potash 2 and manganese 6 : fuse 4 days, and then 
 use. 
 
 Or crystal 99, zaffre 10 oz., manganese 3 oz., calcined 
 iron scales 3 oz. 
 
 Blue. Crystal 99, zaffre 14, cobalt 16, manganese 2 
 oz. (or 1 copper calc), and spice of zaffre. 
 
 Sapphire. Crystal 99, cobalt 14 oz., manganese 2; or 
 'Cassius' purple 2 oz. or 99, smalts 1J. 
 
 Brown. Crystal 50, No. 2, 49, calcined iron scales 
 1 : the frit well pulverise, and add glass of antimony 2 Ib. 
 
 Crysolite. Crystal 99, calcined iron scales 1. 
 
 Carnelian (red). Crystal 99, glass of antimony 14 
 oz., sulphate of iron calcined red 2 oz., and a spice of 
 .manganese. (White), Crystal 99, bone-ash 14 oz., yellow 
 ochre 2 oz. 
 
 Garnet. Crystal No. 1 and 2, frit 99, manganese 15 
 'Oz., zaffre 1 oz., fuse 24 hours. 
 
 Or crystal 99, glass of antimony 1, spice with equal 
 quantities of purple manganese. 
 
 Or crystal 98, glass of antimony 1, and manganese 1. 
 
 Gold colour. Crystal No. 2, 92, borax 1, crude tartar 
 5, manganese 1, willow charcoal 1. (The carbon produces 
 the tint, says Mr. S. More ; Pott used soot and lamp- 
 black.) 
 
 Or with like proportions of nitrate of soda, crude 
 tartar 6, manganese 1, and prussiate of iron. 
 
 Or equal parts of minium, flint, and glass of antimony ; 
 <or 2, 3, and 2. 
 
 Green Emerald. Crystal 99, nitrate of copper 15 oz., 
 .precipitated iron 1 oz. 
 
 Or crystal comp. (4 times fused and cast into water) 
 30, white crystal powder 2, common glass powder 24, 
 minium 18 ; fuse 3 hours and cast into water to separate 
 whatever lead happens to be reduced ; again fuse the frit 
 24 hours, then add nitrate of copper and a spice of crocus 
 .martis for the requisite tint. 
 
 Sea Green. Fuse best crystal 99, calcined brass 14 
 
506 CHEMISTRY OF POTTERY. 
 
 oz., zaffre 24 oz., add very gradually, and prevent loss by 
 effervescence: fuse 3 hours, and prove for tint; afterwards 
 raise the temperature during 24 hours. 
 
 Purple. Crystal 99, zaffre 14 oz., purple Cassius 2 oz. 
 (or zaffre 14 oz., manganese 2 oz.). 
 
 Red. Fuse glass No. 3, 36, crown-glass (or green) 
 70; gradually add red oxide of copper and cream of tartar 
 till the desired tint is obtained. 
 
 Ruby. By repeated solution and evaporation, obtain 
 a red chloride of gold. Crystal glass fuse, and make 
 friable 5 times ; then fuse, and add the gold till the tint is 
 obtained. 
 
 Or Frit Hint 60, potash 12, nitre 13, borax 15. 
 Again fuse this, and to 66 add of mixed Venetian glass 30, 
 Cassius' purple 4, until the tint is obtained. 
 
 Or Cassius' purple 1, borax 7, arsenic 1, tartar 6, 
 nitre 11, and sand 74. 
 
 Topaz. Crystal 50, gold coloured ditto 50 ; fuse 2 
 hours. 
 
 Or Fuse twice over, crystal 55, lead ashes 45, and 
 cast into water; then fuse, frit 66, gold coloured 34. 
 
 White. Crystal 90, bone-ash 10; or 90 flint glass, 
 arsenic 10; fuse carefully. 
 
 In tilling the glass pots with frit for either flint or 
 crown-glass, the temperature is raised to the highest degree 
 attainable by the furnace. The components for the former 
 gradually diminish in bulk by the fusion, during about 
 fourteen hours required to fill the pot; and for the latter, 
 at intervals of about three hours, till the pot is filled; the 
 very high temperature is continued, according to the nature 
 of the components, forty to forty-eight hours for the 
 former, and twenty-four to thirty hours for the latter; 
 whatever impurities (sandiver or glass gall) arise on the 
 surface are carefully skimmed off; the temperature is 
 then lowered, by closing the doors of the cave, the density 
 of the whole mass is almost homogeneous, and the metal is 
 ready for the workman's manipulations. 
 
 Bottle-glass being a compound of the cheapest alkali 
 
GLASSES. 507 
 
 and only the coarsest sand (permitted by the excise) varies 
 much in tint ; and by addition of crown-glass cullet is 
 brightened for champagne or castor-oil bottles. The soap- 
 makers' waste is calcined about thirty hours, ground, 
 mixed with sand, fritted twelve hours, and while in fusion, 
 at intervals, the pot is filled ; the highest temperature is 
 continued sixteen hours, the impurities are skimmed off, 
 the temperature is reduced, the metal increases in density, 
 and the founding is completed. The excess of earthy 
 components and impurity of the alkali, so long subjected to 
 very high temperature, by diminishing the proportion of 
 saline matter present, must be the true cause why green - 
 glass phials excel those of flint to contain corrosive fluids. 
 The Glass Pot is formed of the best Stourbridge clay, 
 75 parts, with 25 of a fine powder of old glass pots, for 
 reasons assigned (p. 461). The best kind of clay is quar- 
 ried at Amblecote, near Stourbridge, in a stratum thirty 
 inches thick, forty-five feet below the coal, and 150 feet 
 beneath the surface. There is a necessity for the clay 
 employed to be the most refractory that can be obtained, 
 as free as possible from calcareous and ferruginous impuri- 
 ties. In proportion to its fatness, or excess of pure alumine, 
 will be its fitness for appropriating a determinate quantity 
 (among the foreign Manufacturers 40 to 80) per cent, of 
 the powder of old glass pots, or of well-baked portions of 
 the clay itself. The following method of determining the 
 composition of glass-pot clay, and likewise the suitability 
 of the native earth, was first proposed by Mon. Bosc. 
 d' Antic: " In very different proportions mix the crude earth 
 and the powder of the baked portion, etc. ; form these into 
 cakes precisely of the same dimensions, length, width, and 
 depth (4, 4, and 1 inches) ; slowly and carefully dry 
 these, and next bake at an extremely high temperature, 
 until their bulk ceases to experience any change in solidity 
 and contraction. Let the whole be carefully inspected, and 
 that composition will be the best whose bulk has been 
 diminished only one-eighteenth part." A man carefully treads 
 mass into a tenacious paste, that is made into rolls, which 
 
508 CHEMISTRY OF POTTERY. 
 
 in successive layers carefully and closely compacted form 
 the receptacle of the metal : no air-bubble remains to 
 expand by heat and cause a rupture. Now that adequate 
 mechanical power is applicable to the throwing-wheel at 
 Etruria (Wedgwood's), and at Stoke (Copeland and 
 Garrett's), to move the heaviest mass of clay requisite for 
 the glass pot and there are throwers with sufficient skill for 
 the proper execution of the task I think there would be 
 economy in bringing the fabrication of the Glass Pot 
 within the sphere of the Potters' Art. During nine to 
 twelve months the pot is subjected to a temperature of 
 50 x Fahrenheit ; then for one month to 90 x ; next it 
 is gradually raised to that of the furnace, into which it is 
 removed with all possible celerity, to replace any which 
 may have failed. 
 
 GLASS-STAINING AND PAINTING. 
 
 To produce glass perfectly colourless requires much 
 experience and notice of the chemical causes of the change 
 of tints that would early occur, which latter would 
 suggest the method of obtaining any desired tint by 
 introducing the requisite metallic oxide into the mass 
 during fusion, as was the pot-metal of subsequent times. 
 The production of coloured glass, therefore, is reasonably 
 considered as coeval with the Manufacture itself, however 
 early; but of recent date, compared with that, although 
 not determined, is the art of depicting objects by small 
 pieces of stained glass, or by colours painted thereon. 
 During several centuries it gradually improved in excel- 
 lence, in mellow rich tint, and calm imposing grandeur of 
 character ; but it has remained for our day to have 
 historical subjects, specimens of the Art, of distinguished 
 excellence for accurate design and details, suitable breadth 
 of surface, delicacy of tints, and truth of effect ; demon- 
 strating the possibility, by combining the varied excellences 
 of early and recent artists, of producing triumphs surpassing 
 
GLASSES. 509' 
 
 any hitherto achieved, and for which is wanting only 
 adequate public encouragement of artists of inventive 
 genius and practical skill. Without this we cannot 
 reasonably expect them to forego the pleasure, as each 
 stroke of the pencil renders the design more obvious, and 
 the success and patronage which adherence to the palette 
 and canvas secures ; and to pursue that study which 
 supplies the best exhibition of taste, yet has the disad- 
 vantages of expensive materials, tedious and precarious, 
 processes, and anxious fear for the injury of his tints by the 
 high temperature of the kiln. It is a matter of prudence 
 to prepare of each colour a quantity adequate to the com- 
 pletion of the design, that the beauty of the whole may be 
 preserved by superseding the liability to change of tint 
 from several preparations. 
 
 In this Art may every variety of pictorial design be 
 executed. As modern ingenuity combines the requisite 
 tints of the subjects on the same sheet of glass, and 
 incorporates them therewith by raising the temperature till 
 the components fuse together for landscapes are afforded 
 peculiarly powerful contrasts of light and shade, and for 
 flowers all the splendour and delicacy of tints exhibited in 
 Nature. And with the advantage of being indestructible,, 
 except by violence ; all the Colours and Stains used being 
 either metallic oxides or minerals, which during the raised 
 temperature incorporate with, and penetrate the substance 
 of the glass ; the former, semi-transparent, dosed with 
 a flux, promote combination with the surface ; the other 
 permeate the glass, without injuring its transparence. The 
 components of the best crown-glass most readily combining 
 with metallic oxide, our artists usually employ it. I have 
 not been informed of any using British sheet-glass. The 
 Stains are only three : Orange. Fuse together pure 
 silver 66, antimony 34 ; pulverise and grind 14 of frit with 
 Venetian-red 86. Red. Add to the above 99, sulphuric 
 acid 1. Lemon-yellow. From the nitric solution of silver 
 precipitate the metal by test 26 ; of this precipitate add & 
 parts to 82 of pure alumine, and mix well for use in 
 
510 CHEMISTRY OF POTTERY. 
 
 distilled water ; then evaporate to a proper consistence for 
 use (or alter the alumine for change of tint). 
 
 The judicious inspector of these productions will 
 denounce as erroneous, unjust, and absurd the opinion 
 resulting from indiscriminate fondness for the antique, that 
 excellence is confined to the productions of the 14th and 
 15th centuries, in brilliance of tint, and grandeur of 
 character ; for, with the like tints, equally brilliant, rich, 
 varied, and durable, are many others, then not used, 
 probably because not known ; as pink, pale lemon, and 
 several compound colours. The ancient ruby-tint alone 
 remains unequalled.* The artists possess all the resources 
 of their predecessors, and likewise other facilities, for 
 excellence ; they are better acquainted with the principles 
 of the science of drawing, and the fluxes proper to adapt 
 different colours for using on the same sheet, so that every 
 requisite tint can be introduced, and instead of scores of 
 small pieces as formerly, a few sheets only are needful for 
 the design. By patient and attentive study of the isolated 
 magnificent old English, or pointed style, as exhibited in 
 remains, and the invaluable elucidations of able antiquaries 
 and draughtsmen, our artists will be prepared to give all 
 possible effect to their embellishments of noble edifices, 
 without the liability of failure consequent on attempting to 
 enlist the principles of the Greek and Italian schools into 
 
 * Boyle mentions the accidental production of this tint. In a letter 
 on imbuing glass with metallic colours, he details his own experiments to 
 obtain the ruby-tint, and then mentions an artist, who, desirous to effect 
 some purpose with an amalgam of gold and mercury, attempted to form 
 it by keeping the two metals fused together in a glass retort, which after 
 some time burst with a tremendous explosion, and the fragments excelled 
 in fine ruby-tint any Mr. Boyle had ever seen. 
 
 Kunkel, in 1670, made a cup and cover of ruby-coloured glass, still 
 preserved and very highly valued at Berlin. Another, most prized by its 
 maker, is 1 inch thick and 24 Ibs. weight. He states, that frit of best 
 glass 999 and purple 1 will give the full rich ruby colour. Recent 
 experiments prove, however, that to 86 purple must be added 14 of 
 the white oxide of antimony. The better the quRlity of the former, and 
 the purer the latter, the more beautiful will be the resulting tint. 
 
GLASSES. 511 
 
 their service, for figures, groups, foliage, etc. ; and by 
 avoiding the gaudy, vulgar, deep tints when executing the 
 strong varied outlines will the specimens become all that 
 is desirable. 
 
 ENGRAVING ON GLASS. The glass most esteemed 
 throughout Europe, in the 16th century, had the name 
 Venetian* because made at the village of Murano, nigh the 
 city of Venice. The mirrors especially were in great 
 demand, and by their excellence superseded those of metal. 
 The sheets had designs executed on them with the 
 diamond, an acid liquor capable of corroding glass not 
 being then known. Professor Beckman (in his History 
 of Inventions) ascribes this latter method to Henry 
 Schwanhard, a celebrated glass-cutter of Nuremberg, 
 who, in 1670, accidentally corroded and rendered quite 
 soft his spectacles by some aqua regia so called, thereby 
 suggesting a method to readily execute designs or writing 
 on sheets of glass. The learned Professor's opinion is well 
 grounded, that Schwanhard had discovered and used, as 
 did likewise his pupils, for this purpose, the substance now 
 named fluoric acid; for his method was, to correctly 
 draw out the design with a proper varnish, that would 
 preserve all the figures and tracing from the action of the 
 corrosive acid, which affected all the surface contiguous to 
 them, leaving them smooth, clear, and in relief on a dim 
 ground when the glass was cleaned ; whereas the practice 
 
 * The glass-works at Murano now make tubes for beads. The workman 
 takes a portion of each of the coloured glasses from the pots, which after 
 being well twisted or rolled together, is blown into a cylinder ; a second 
 workman then attaches his instrument to the other end, and on a gallery 
 150 feet long, they run in opposite directions and form a tube, whose 
 diameter accords with the quantity of the metal taken up at first. The 
 tubes are sorted accordingly ; then chipped into sizes which are agitated 
 among sand and wood-ashes in a bowl, till the aperture is filled; next in a 
 metal tray, and with more wood -ashes and sand over a charcoal tire they 
 are constantly agitated, till they are spherical ; afterwards they are sepa- 
 rated from the sand and ashes, and thrown into sieves of varied meshes, 
 to determine the sizes. 
 
512 CHEMISTEY OF POTTEKY. 
 
 of our day is to varnish the surface with isinglass-size or 
 oil of turpentine and ceruse. At Beckman's suggestion, 
 some artists verified satisfactorily the process subjoined, 
 conjectured to be that of Schwanhard and his pupils, 
 communicated to Kruntz, and by him published in the- 
 Oekonomische Encyclopddie, 1725. 
 
 "When the spiritus nitri per distillationem has passed into the 
 recipient, ply it with a strong fire, and when well dephlegmated, pour it,, 
 as it corrodes ordinary glass, into a Weldenberg flask, then throw into it 
 a pulverised green Bohemian emerald, otherwise called hesphorus [the 
 green fluor spar, says Beckman], (which, when reduced to powder, and 
 heated, emits in the dark a green light), and place it in warm sand for 24 
 hours. Take a piece of glass well cleaned, and freed from all grease by 
 means of a ley ; put a border of wax round it, about an inch in height, 
 and cover it all over with the above acid. The longer you let it stand, so 
 much the better ; and at the end of some time the glass will be corroded, 
 and the figures which have been traced out with sulphur and varnish 
 will appear as if raised above the pane of glass." 
 
 The Manufacturer will find his account in preserving 
 correct standards of his productions; variation from which, 
 in specific gravity, will prove a change, and likewise the 
 remedy, in the proportions of the components. As glasses 
 with these of only silica and alkali, or silica and minium, at 
 determined temperatures, with the additional quantity of 
 alkali, or of oxide, increase their specific gravity, then, 
 from knowing the varied proportions of components, and 
 difference of specific gravity of two kinds of glass, may be 
 determined, of a third, the specific gravity, by the alkali, or 
 oxide, present, or these by the other respectively. 
 
 / No. 1, of silica 80, alkali 20, has 236 specific gravity 
 
 1 2, - 54, 46, 254 difference 26 & 18 
 
 f- i, _ 27, Minium 73, - 520 - 
 
 I 2, - 11, - - 89, -657- - 16 & 137 
 
 From these data, to determine the proportions of the 
 like components, for glasses No. 3, with specific gravity 
 242 and 579: As the difference between the specific 
 gravities, also the weights of oxide, of the glasses 1 and 2, 
 = 18 and 16, is to that between the weight of oxide, and 
 specific gravity in 1 and 3=6 and 7, so is the difference 
 
GLASSES. , v .i. : 513 
 
 between the weight of alkali and the specific gravity in 
 1 and 2 . = 26 and 137 r to the difference between those of 1 
 and 3 == 9 and 59. Adding each number to thafc of the 
 alkali, and the oxide, in. 1, the glasses 3 must be silica 71, 
 alkali 29, and silica 20, minium 80. 
 
 The presence of lime greatly increases the specific gravity 
 of glass ; whenever, therefore, this property exceeds the 
 standard adopted, excess of either lime or alkali is present, 
 and needs to be appropriated. 
 
 Flint-glass combines silica, minium, and alkali at a 
 temperature lower than those at which the other kinds 
 are founded. The specific gravity of glasses from various* 
 compounds is determined thus : When at the like tem- 
 perature silica 76 and alkali 24, or silica 24 and minium 
 76, chemically combine, the glasses have the specific gravity 
 24 and 54. And the glass from either the raw components,, 
 in these proportions, or equal weights of the two preceding, 
 properly founded, has that specific gravity deduced by 
 calculation (unless a difference be caused by corrosion of 
 the glass pot). Supposing that at a certain temperature 
 the silica appropriates one portion, the minium, and the 
 other, the alkali requisite for perfect vitrification, excess of 
 the latter being dissipated, the specific gravity can be thus 
 determined : In using silica 100, minium 50, potash 40, 
 during the founding, the minium is reduced to 48, which is 
 appropriated by 16 of silica, forming glass 64, with specific 
 gravity 54. The potash 40 likewise is reduced to 28, which 
 is appropriated by the silica 84, forming glass. 112, with 
 specific gravity 24. Were the raw components founded, 
 the loss of minium 2, potash 12, leaves 176 of glass, 
 of the specific gravity determined thus : Multiply together 
 the 54 and 24 of the two glasses = 1296, and this by 
 the weight 176 = 228,086, which divide by the product 
 of multiplying respectively their weights and specific 
 gravities, 7584, and the specific gravity will be 3013, 
 when the founding properly succeeds. The verification 
 this affords of the principle given, p. 48, is to myself very 
 interesting. 
 
 2 L 
 
514 CHEMISTRY' OF POTTERY. 
 
 The facilities for communication have so generally 
 diffused current knowledge, that the artisan in his work- 
 shop, equally with the student in his closet, has thence 
 delightful employment and invigoration of the mental 
 faculties, capacitating for ready appropriation of other 
 stores, or the practice of any suggestions, by which he may 
 become a more skilful workman, also a more useful and 
 better member of society. 
 
 The solution of the problem To make (for optical 
 purposes especially) glass homogeneous, transparent, hard 
 and refractive has excited the ingenuity and attention of 
 many glass-makers. Mere mechanical mixings were as 
 .successful probably as could be expected, but the uncertain 
 composition of some of the materials may render the theory 
 uncertain, and by incongruous appropriations preclude the 
 desirable and indispensable data. We expect these to be 
 clearly ascertained, because much important information 
 has been elicited for future guidance. Invited by the Royal 
 Society, Dr. Faraday brought his great experimental skill 
 to its investigation, with considerable advantage to the art. 
 His rough-glass furnace is an interior iron box, 8J inches 
 deep, 14 wide, and 30 long, lined with refractor}^ fire- 
 bricks ; in the bottom is fixed a grate, 12 by 8 inches; 
 at the front is a common furnace iron door, and in the 
 end is a funnel-pipe to enter a long flue; on the lining 
 rests a perforated iron cover for receiving the crucibles. 
 The fire-chamber is 12 inches square, 5| inches deep, with 
 sides 2 inches thick. The crucibles are 5 inches high, with 
 the bottom diameter 3J inches, and the top 3 inches, of the 
 finest and most refractory porcelain, as thin as will safely 
 sustain extremely high temperature. The covers are 4J inch 
 evaporating basins, slung in platina wirej with a loop for 
 removal by an iron rod. The materials are, nitrate of lead 
 154'14, silicate of lead 24'00, and crystallised boracic acid 
 42'8; the coals are ignited, and all the space around is 
 filled with coke. As the composition condenses by rise of 
 temperature, successive additions are made, and the whole 
 is carefully agitated during two hours to prevent the 
 
GLASSES. 515 
 
 defects named striae, threads, tears, and knots ; * and the 
 highest temperature the crucible will bear is continued 
 some hours, until it ceases to evolve even the most minute 
 bubbles of gas or vapour. The better to promote this a 
 portion of spongy platina and of materials are first well 
 mixed together, and afterwards mingled with those of the 
 mass, prior to filling the pot ; and the infusible metal, as a 
 nucleus, during the rise and agitation of temperature, 
 causes all gas or vapour to evolve, and then completely 
 deposits. The rough glass is either removed with a platina 
 ladle into platina trays, or cast into plenty of distilled 
 water in a very deep flint- ware jar, by which it is much 
 divided ; next it is drained, dried well, and preserved in 
 clean bottles. The finishing furnace is a parallelepiped of 
 brick-work, with a fire-chamber 25 inches by 12f, beneath 
 which is a receptacle for coke, also the flue for the passage 
 of the flame and smoke from the fire-place at one end ; and 
 in the ash-pit, a sheet-iron trough filled with water, 
 constantly prevents clinkers closing up the bars of the 
 grate. In the fire-chamber is properly secured a tray, of 
 suitable size, made of the best platina, carefully rolled, so 
 that 1 inch weighs 17 '5 grains, and without the smallest 
 hole. When spongy platina has not been already used, it 
 is triturated with powder of the rough glass, and mingled 
 with the remainder. The tray is filled with the rough 
 
 * Striae are undulations in the glass from incongruous particles of the 
 components, equal to the other portions in transparence and vitrescence, 
 separating perfect portions, and bending or refracting the rays of light, so 
 as to distort the appearance of objects viewed through them. As these 
 objects are necessarily much magnified by optical instruments, equally so 
 will be the distortion by even very minute defects in the glass, which 
 consequently precludes the accuracy of vision designed to be obtained. 
 Only when very obvious, however, are stria?, detrimental to the glass used 
 for the usual purposes of society. 
 
 Threads are the greenish fibres in glass which by change of tem- 
 perature dilate and contract, caused by particles of clay remaining unap- 
 propriated by the temperature, rendering the mass extremely fragile. 
 
 Tears form the greatest imperfection in glass, caused by portions of 
 clay from the dome of the furnace, or arch, dropping into the pots and 
 
 2 L 2 
 
516 CHEMISTRY OF POTTERY. 
 
 glass and covered, while the temperature is raised during 
 about one hour ; the mass is then carefully agitated, and 
 likewise often during two hours more ; and a very high 
 temperature is attained and continued from 6 to 12 hours 
 after the whole mass has assumed a state of perfect repose. 
 From the quantity mentioned, Dr. F. obtained glass 152 ; 
 of protoxide of lead 112, silica 16, dry boracic acid 24> 
 with specific gravity 5'44, or with borate of lead 6'4. The 
 hardness is a result of minimum of lead, with borate, soft ; 
 biborate, harder; and tri-borate, hardest, equal to flint- 
 glass ; silicated borate, softer than flint glass, which last is 
 equalled by a glass, of minium 30, oxide of silver 28, 
 boracic acid 42, of much excellence in colour, and increased 
 fusibility. Sir J. Herschel's three experiments demonstrate 
 that Dr. F.'s glass, equally with flint-glass, corrects the 
 dispersive powers of crown or plate-glass, in ratio of the 
 specific gravity: 
 
 Bor. Lead. Sil. Bor. Lead. 
 
 Angle of glass prism = 29 6' 30 26' 
 
 Kefractive index for extreme red rays ^ = 2-0430 1-8521 
 
 Ditto maximum yellow = 2-0652 1-8735 
 
 Ditto extreme violet = 2-1223 1-9135 
 
 S/* 
 Dispersive index = /A _i 3-0740 0-0703 
 
 being partially vitrified with the glass, which it renders so brittle that 
 instances have occurred in which it has cracked by unequal expansion 
 from slight change of temperature. 
 
 Knots are caused by aggregation of particles of silica imperfectly 
 vitrified ; or portions of glass-gall left when skimming the pot ; or 
 fragments of the pot or furnace accidentally abraded by the tools or 
 other cause. 
 
 Bubbles are caused by portions of gas which evolve during the found- 
 ing, but have not been dispersed, because the glass has been too tenacious, 
 owing to either deficient temperature or excess of silica. The appearance 
 is their chief defect ; for even when numerous, the sum of their areas united 
 is only a small proportion of the whole surface of the glass ; and each acts 
 as a small convex lens, rapidly turns aside the rays which strike against it,, 
 and slightly diminish the light in proportion to its area. 
 
[ 517 ] 
 
 CHAPTER III. 
 
 COLOUES. 
 
 THE first attempts at artificially combining with 
 subjects, colours not previously present, were anterior 
 to any known record thereof, and originated in the 
 desire to gratify natural fondness for variety and 
 finery. Man, rude or polished, reared in the wild or 
 the palace, feels a sense of pleasure while regarding 
 the splendour of coloured subjects in which lively 
 tints are displayed and contrasted, as in the endless 
 variety of the parterre, and the delicate plumage of 
 the songsters of the grove ; and in the less cultivated 
 state he would attempt to colour apparel or utensils 
 with some production supplied by Nature. The 
 colours thus obtained at some sacrifice of time and 
 trouble would be some permanent, others evanescent, 
 and their application rude and imperfect, yet sug- 
 gesting new ideas by the defects, and fresh efforts 
 by the failures, because of ignorance of principles. 
 Progress in refinement would introduce fresh 
 methods more successful, and with the aid of fresh 
 materials gradually urge onward the Art itself, until 
 it assumed the importance which it still enjoys, as a 
 
518 CHEMISTRY OF POTTERY. 
 
 source of respectability and opulence to some, and of 
 employment to numbers. 
 
 I am not required to determine the priority of 
 application of metallic oxides to colour ornaments 
 or transparent glass. The employment of vitreous 
 colours at a very early date by the Egyptians is de- 
 monstrated by the beads found on many of the 
 bandages of their mummies, and preserved orna- 
 ments, fabrications of the early Greeks, Romans and 
 Saxons, proves its practice by those people. Glass is 
 known also to have been a very early Manufacture ; 
 and almost coeval with its commencement (whether 
 by accident or design is not of moment) was its dif- 
 ferences of colour. There is great probability that 
 it was the result of mere accident ; stated to have 
 been that some sailors having made a large fire with 
 dried marine vegetables on the beach, the alkali and 
 silica combined and fused into clear glass.* That 
 both methods were early pursued both in Egypt and 
 Phoenicia, cannot with propriety be questioned, 
 though we remain unacquainted with the processes, 
 of whose perfection we judge only from its capability 
 of answering deceptive purposes, f These necessarily 
 involve some acquaintance with the chemical pro- 
 perties of metallic oxides for producing the colour 
 desired ; and still their ignorance of the mineral 
 
 * " Fama est, adpulso nave mercatorum nitri, cum sparsi per 
 littusepulaspararent, nee esset cortinis attollendislapidum occasio, 
 glebas nitri e nave subdidisse. Quibus accensis, permixtu arena 
 litoris, translucentes novi liquoris fluxisse rivos ; et hanc fuisse 
 originem vitri." PLINI, Nat. Hist. lib. xxxvi. cap. 65. 
 
 fThus denounced by Pliny " Adulterantar vitro simillime ! 
 sed cote deprehenduntur, sicut aliae gemmae factitise. 
 
COLOURS. 519 
 
 acids in our day best known as the proper and 
 readiest solvents of oxides renders the determination 
 of their means and manipulations a difficult task. 
 
 Klaproth's analysis of 200 grains of antique red, 
 yellow, and blue glasses, gives these components and 
 proportions : 
 
 Bed. Yellow. Blue. 
 
 Silica 142 130 163 
 
 Alumine 5 11 3 
 
 Lime 3 13 0-5 
 
 Oxide of lead 28 15 
 
 -Copper 15 20 1 
 
 Iron 2 7 19 
 
 195 196 186-5 
 
 The green glass has precisely the same components 
 as the red, only varied in proportions, and with per- 
 oxide instead of protoxide of copper. Similar 
 specimens of red and blue enamels often occur in 
 the scoriae of the copper and iron smelting furnaces. 
 But the problem of their production we cannot solve, 
 because not sufficiently acquainted with the circum- 
 stances and conditions, like as of those by Nature 
 adopted that iron may tinge the sapphire, lapis, lazuli, 
 blue clays, etc., in which Klaproth detected it; and 
 Gmelin has proved its utility for tinging glass of a 
 beautiful blue, suspected by Delaval to have been 
 produced by cobalt, though this was first so employed 
 about A.D. 1540, by Christopher Schurer, glassmaker, 
 Flatten. 
 
 To every reflecting mind the fact will be clear, 
 that the application of principles will approximate to 
 perfection the preparation of vitreous colours, without 
 
520 CHEMISTRY OF POTTERY. 
 
 denying that in their absence, and disregard of a 
 correct theory of chemistry, repeated mixing of in- 
 gredients patiently pursued must have credit for the 
 high degree to which the Art has attained. When 
 intelligent artisans direct the processes, and fully 
 detail the results to philosophers, its progress will be 
 rapid, certain and "onward." The observation of 
 any new fact becomes a matter of general concern, 
 and demands philosophic consideration when its in- 
 fluence is likely to extend beyond the single circum- 
 stance to which is owing its discovery. Only when 
 directed by principles can the artisan's skill and 
 attention, in adapting the proportions of the different 
 components, and his labour in the peculiar manipula- 
 tions, for the numerous and diversified colours, be 
 most economically and profitably employed in this 
 extremely important and interesting branch of the 
 Manufacture. 
 
 COLOUR-MAKING. 
 
 IN this the improvements in the supply of the 
 palette will accord strictly with the employment of 
 bright colorific oxides, not changeable by the com- 
 ponents of the glaze. Their reciprocal combinative 
 potencies, and difference of orbital spaces, adapt them 
 for combination respectively with certain momenta, 
 till their progress or deeper penetration into the glaze 
 from the surface ceases, or is interrupted, because all 
 potency is appropriated. 
 
 Metallic oxides are the only substances employed 
 as the bases of vitreous colours ; and among Nature's 
 
COLOURS. 521 
 
 vast supply, many can be rendered useful for the 
 purpose ; as, by proper preparation, they give to any 
 vitreous surface a brilliance of tint, and to glass a 
 rich beauty, almost equalling that of natural gems. 
 Seldom are the oxides used alone, and all oxides, 
 even of the same metal, are not always useful as sub- 
 stantive colours, though as components they are 
 available, because of the change consequent on baking 
 the enamel, as the yellow oxide of gold, the black 
 and green oxides of copper, the puce and red oxides 
 of lead, the oxides of mercury, arsenic, etc. 
 
 ENAMEL strictly signifies a delicate white opaque 
 vitreous compound applied to a metallic recipient, 
 from which its import is extended, in this Manu- 
 facture, to a vitreous compound of metallic oxides 
 and silica, susceptible of the most beautiful and 
 brilliant tints, whether opaque or translucent ; while 
 the porcelain glaze itself is, by its delicate white- 
 ness and beautiful texture, especially adapted as a 
 ground, superior to any other for preserving the 
 delicacy, strong brilliance, and richness of tint, of 
 the finest efforts of the pencil. 
 
 The properties of chrome, cobalt, copper, iron, 
 lead, manganese, gold, tin, etc., have been long known ; 
 and interest has induced acquaintance with the 
 metallurgical processes usually adopted for their 
 treatment ; but chemistry has not yet shed the rays 
 of her lamp sufficiently on them for the transpiring 
 facts to be adequately explained by theory. The 
 preparation of these metals as colours involves many 
 difficulties, because their purity and lustre must be 
 preserved with a fusibility at a temperature which 
 does not destroy the combination of the components 
 
522 CHEMISTRY OF POTTERY. 
 
 of the enamel, yet softens the compound sufficiently 
 to commix with the glaze. Alone metallic oxides 
 do not fuse, though at a very high temperature they 
 are appropriated by the glaze, usually with a very 
 dull tint. To prevent this dullness, the components 
 of the glaze are regarded in the mixture of substances 
 with these oxides as &flux. 
 
 The colours employed on enamel are the earliest, 
 except those of Nature. When used for soft porce- 
 lain and flint ware, they need less flux than for the 
 hard, because the recipient silicate of lead, or of 
 borax, readily softens and appropriates the metallic 
 oxides and alkaline components. The lead and borax 
 fluxes are useful in their respective applications, 
 and facilitate the employment and fixing of the 
 colours. But as borax does not dilute with gum, 
 it is not a component of the flux of those colours 
 which are ground up with gum-water. 
 
 Changes in the beauty of the tints arise from 
 two causes not from their composition, but the 
 nature of the recipient, and the baking. The oxide 
 of lead in the glaze affects several of the colours, as 
 those of iron, in a remarkable manner.* The enamel 
 baking softens the glaze for the colours to easily com- 
 bine ; and whenever they become diluted by such 
 combination, as often occurs, the baking changes into 
 a slight sketch the painting which seemed finished. 
 Hence only are the needful strength and brilliance of 
 tint obtained by frequent re-touchings and bakings, 
 by which the colours are no more distinguishable, 
 
 * Brongniart has the merit of first publishing this fact, which 
 had caused such losses to the Staffordshire Manufacturers. 
 
COLOURS. 523 
 
 than when applied to canvas. Certainly they are 
 always soft, but they never scale off and injure the 
 design. 
 
 The hard porcelain having for its base the very 
 white alumine, called kaolin, mixed with a silicious, 
 calcareous, and alkaline solvent (hence the alumine 
 preserves almost the natural tints which acids always 
 modify), and whose glaze is only the fusible felspar, 
 fused with only borax and barytes (not an atom of 
 lead), requires two kinds of colours, the one many 
 and varied for representing different subjects, of 
 almost like components with those for soft porcelain, 
 and by the additional dose of flux adapted to bake at 
 a temperature many degrees below that required to 
 bake the glaze ; the other a few technically named 
 grounds, applied to the general surface, bake at a 
 temperature only a few degrees below that for the 
 glaze. 
 
 The temperature needful to bake the colours 
 expands the orbital spaces of the components of the 
 glaze, by which portions of the flux and colorific 
 oxides are appropriated, merely with a diminution of 
 their strength by transparence ; the glaze not be- 
 coming semi-fluid, and so appropriating deeply and 
 changing the colours. When great care is employed 
 in adjusting the equivalence of the alkali introduced, 
 seldom does the annoyance ensue of scaling off of 
 the colours required for finishing the design by re- 
 peated touchings and bakings. There being only the 
 proper quantity present for affecting the glaze, no 
 extra volatilisation of alkaline particles occurs to in- 
 jure the tints. The proper mixture of the colour on 
 the palette prior to using, and a due portion of lime 
 
-524 CHEMISTRY OF POTTERY. 
 
 in the glaze, and of flux in the colours, will generally 
 prevent the unpleasantness of faint designs. As only 
 few metallic oxides do not volatilise but remain 
 fixed and unaltered in tint at the high temperature 
 needful to bake the glaze of hard porcelain, only few 
 colours can be employed as grounds for the general 
 surface, yet chemistry will determine their economi- 
 cal employment and kinds. When their solvent is 
 felspar, they incorporate with the glaze, acquire extra 
 brilliance, and never craze. 
 
 Pure water is preferred in grinding, or render- 
 ing sufficiently comminute, the colours, because in it 
 they grind freely and readily, and therefore are more 
 efficiently reduced, and yet separated from any impu- 
 rities that are divided and carried off by evapora- 
 tion. The presence of volatile components, as when 
 litharge is in the water, must be regarded by the 
 grinder, because the noxious effluvium is injurious to 
 the lungs. In proportion to the requisite degree of 
 comminution must be the quantity ground at the 
 same time, because the finer it is required, the 
 smaller must be the quantity brought under the 
 -action of the muller (as fine gold, for instance). 
 When substances are introduced merely to modify 
 the colours, they are mixed in very small quantities 
 till the required tint is obtained. 
 
 Brongniart recommends to take the enamel from 
 the crucible ; * first fracture the lumps small by a 
 
 * Crucibles for the fusion of metals only have black lead (car- 
 buret of iron) intimately mixed with Stourbridge clay, or the 
 white marie of Shelton and Hot-lane. As this is refractory at any 
 temperature, yet without combinative potency with the clay which 
 protects it from the action of the atmosphere, the crucible is 
 
COLOUKS. 525 
 
 hammer, then pulverise in a mortar to a fineness- 
 which will pass through a sand sieve ; then well 
 levigate, and carry over, by stirring the fluid, the 
 fine powder, which must be left to subside ; again 
 pulverise the calc, and repeat the process until a 
 sufficient quantity of fine powder is obtained ; and 
 the remainder will have different degrees of fineness 
 in the respective portions. 
 
 Various compounds are used to promote the 
 fixation of the metallic oxides in the glaze of the 
 ware ; and because of more easy vitrescence, during 
 the baking of the colours, are called hard or soft 
 fluxes. These, when carefully adapted to the com- 
 ponents of the colours, and of the glaze respectively, 
 preclude dissatisfaction and disappointment, as well 
 
 incombustible, less than any other compound affected by the 
 raised temperature, yet without retaining, as do the sides of 
 other crucibles, any portion of the fused substances. But for 
 saline substances other arrangements are made. ^Well-weathered 
 marie, which has been exposed to the action of the atmosphere, 
 worked by manual labour upon a suitable plot of land, several 
 days in succession, and is usually passed between strong iron 
 cylinders. This marie 50 parts, flint ware shards 25, and coke 
 in powder 25, are well mixed together by sifting ; then water ia 
 added as needed, and the mass is beaten with mallets till well 
 solidified. To form the crucible, a lump of this is placed in a 
 well-oiled sheet-iron mould of the required size and shape ; into 
 this a suitable-shaped piece of hard wood of the proper form is- 
 forced by the screw-press, or the squeezing box ; thus readily is 
 obtained at once a crucible, and afterwards each is carefully and 
 slowly dried ; and when properly used, they will repeatedly bear, 
 without failure, a very high temperature. This method will form 
 the best crucibles ; and the size as well as the thickness may 
 thus be readily secured, from 10 inches high and 8 diameter, to 
 2 inches by 1J, tapering gradually to the bottom. 
 
526 
 
 CHEMISTRY OF POTTERY. 
 
 as sacrifice of time, labour, expense and credit with 
 the purchaser. It will be found that scarcely any 
 colour requires so large a dose of flux as 6 to 1, 
 which enveloping the metallic base or oxide, pro- 
 motes its vitrescence at a heat below what would 
 destroy its splendour, fixed and rendered permanent 
 on the porcelain. The varied heat proper to fuse 
 different oxides with fluxes renders requisite care in 
 apportioning the flux, so as to preserve the brilliance 
 in even the finest lines ; and when properly observed, 
 the ware presents the softness of the richest velvet, 
 and the lustre of the most beautiful satin, without 
 the possibility of decomposition. 
 
 COMPONENTS AND PROPORTIONS OF FLUXES : 
 
 K. lead 
 Flint 
 Borax 
 
 Cullet 
 W. lead 
 
 1 
 
 2 
 
 8 
 
 45 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 111213 
 
 14 
 
 1516 
 
 17 
 
 18 
 
 19 ! 20 21 22 23 
 
 Nitre 
 
 Potash 
 L. sand 
 
 18 
 
 4H 
 34 
 
 17 
 50 
 33 
 
 35 
 
 25 
 40 
 
 3650 
 1415 
 5035 
 
 50 
 40 
 10 
 
 46 
 12 
 9 
 33 
 
 18 
 34 
 
 50 
 
 41 
 
 23 
 30 
 
 28 
 
 48J...30 
 15... 40 
 
 53 
 
 50 
 
 50 
 
 42 
 
 r>3 
 
 6250 
 9 
 
 ...L.L; 
 
 611; 9 
 30 39 36 
 14L. 9 
 50 50 46 
 
 17 
 55 
 
 301036 
 770 4 
 ...!20... 
 
 25 
 22 
 
 6 
 
 12 
 32 
 
 32 
 1 
 17 
 
 42 
 2 
 14 
 
 8 
 4 
 25 
 
 J 
 
 Dj... 
 
 4 9 
 
 2832 
 
 The flux is employed to secure to the respective 
 tints, after baking, strength, brilliance, and per- 
 manence, by the enamel being homogeneous with 
 the glaze ; to preserve from further separation the 
 comminute particles of the metallic oxide ; to pro- 
 tect the tints from atmospheric action ; also, to 
 promote combination of the enamel with the glaze 
 at a temperature much lower than was required for 
 its baking ; and, by a precise supply, to preserve the 
 tints from injury. 
 
COLOURS. 527 
 
 COMPONENTS OF THE COLOURS. 
 
 THE best colours now used in the Art have these 
 components : REDS, oxides of gold and iron ; PURPLES, 
 oxides of cobalt, chromium, tin and calcium ; PINKS, 
 oxides of chromium, calcium and tin ; BROWNS, 
 oxides of chromium, iron and manganese ; BLUES, 
 oxides of cobalt and silica ; mat-blue, oxides of cobalt, 
 lime and zinc ; YELLOW and ORANGE, oxides of lead, 
 silver and antimony ; GREENS, yellow or emerald, 
 oxides of chromium and silicon ; blue or celeste, 
 oxides of chromium, cobalt, silicon and zinc ; green- 
 edge, oxides of copper and chromium ; BLACKS, 
 oxides of cobalt, nickel, manganese, chromium and 
 iron. 
 
 REDS, etc., obtained from Gold. 
 
 There is indispensable an accurate detail of the 
 precise proportion of components, also of the several 
 processes for the production of the simple colours, 
 that each may be fine and clear, yet sufficiently 
 fusible to freely bake with the glaze.* 
 
 Gold was named by the alchemists the king of 
 metals ; and after a solvent was discovered, it was dis- 
 tinguished as kings'- water, or Aqua Regia. Several 
 compounds, however, now bear this name, and as 
 their components differ much, even when applied for 
 a specific purpose, they are submitted to the reader. 
 The liquid itself is strictly a medium for the metal to 
 
528 CHEMISTRY OF POTTERY. 
 
 be in that condition in which it will have reciprocal 
 potency for combination with chlorine. Nitrous 
 acid saturated with nitrous gas has been mixed with 
 concentrated muriatic acid ; but because devoid of 
 reciprocal potency, the effect was as feeble as would 
 have been that of the nitrous gas on water, and the 
 mixture was inert on gold and on platinum. 
 
 1. Muriatic acid of the strength 1-162 treat with nitrous acid 
 vapour until saturated. 2. (Henry) Nitric acid of the strength 
 1-42, 66 parts, and 34 of muriatic acid at 1-149. 3. (Proust} 
 Nitric acid at 1-45, 20 parts, and 80 of muriatic acid at 1139. 
 These proportions also are directed by Gray, but the strengths are 
 1-42 and 1-128. 4. Nitric acid at 1-392, 33 parts, and 77 muriatic 
 acid at 1-149 . 5. Nitric acid at 1-145, 66 parts, and 34 muriatic 
 acid at 1-139. 6. (Keir) Sulphuric acid at T80, 50 parts, nitre 
 25, and table-salt 25. 7. Sulphuric acid 67 parts, nitric acid 
 at 1-392, 33, and saturate with table-salt. 8. Nitric acid at 1-15 
 saturate with table-salt. 
 
 The aqua regia must be of the specific gravity 1-062, or higher, 
 for most efficiently and economically dissolving gold, and will be 
 readily ascertained by using a phial that holds exactly four ounces 
 of distilled water, and when filled with acid contains precisely four 
 ounces and a quarter thereof. When below this, carefully must 
 the liquid be evaporated to the requisite strength. The tempera- 
 ture also must be raised 1 and 4 to 80 Fahrenheit ; 2 and 5 to 
 100 ; and 3, 6, 7 to 110. Although the acids may be colourless 
 (seldom in those of commerce), the mixture will be primrose-yellow, 
 and the tint will grow deeper while the temperature is raised, 
 because chlorine evolves ; the darker it is, the more diminished 
 is its combinative potency with the gold; consequently, much 
 attention is needed to the degree and heat, and its continuance. 
 
 Solution of Gold. To the aqua regia add a small portion of 
 grain gold, and when it is dissolved, repeat the dose, until satura- 
 tion is nigh ; then diminish gradually till no more is appropriated 
 by the acid. Ascertain the quantity of gold in the solution, and 
 the specific gravity of the liquid, for a standard in future. 
 
 Solution of Silver (for the Purple). 1. In pure water 50- 
 
COLOUES. 529 
 
 parts, and 50 of nitric acid of the strength 1-145, at the tempera- 
 ture 110, add doses of grain silver as directed for the gold. 
 Keep in the dark this solution. 
 
 2. Aqua Reyince, Queen's Water (and the only bath in which 
 the Queen of Metals can wash herself free from intrusion). To 
 sulphuric acid at 1-80, 88 parts, add 12 parts of nitrate of silver 
 after it has been in solution in pure water, and re-crystallised. 
 Water is not required for silver, but 'must be added, 66 acid to 
 34 water for other metals. The mere heat of our furnaces does 
 not oxidate silver ; and its extreme indifference to the presence 
 of oxygen, even when it has been supplied by acids, is only 
 counteracted by employing an easily verifiable substance, which 
 appropriates the oxide as it is formed, at a temperature incapable 
 of reducing it to the metallic state; 
 
 Solutions of Tin. 1. The aqua regia 5 or 8, at 112 Fahren-, 
 heit, saturate with small and repeated doses of grain tin. 2. 
 Muriatic acid at 1-149, and temperature 112 Fahrenheit, saturate 
 in a similar manner ; but ahoays in daylight, because hydrogen 
 evolves during the process, and the flame of a candle would be 
 liable to cause a dangerous explosion. This solution is excellent,, 
 because it does not coagulate. 3. (Berard's Method, see p. 357). 
 4. To muriatic acid (at 1*149) 60 parts, add nitre 40 parts ; and 
 when fully dissolved, to 67 of the liquid add 33 of grain tin, cover 
 close to exclude the oxygen of the atmosphere, and keep the 
 temperature at 100 3 hours. When the metal is in solution, 
 the unappropriated chlorine will solicit nitre 20 and tin 20 parts 
 additional ; then to 60 parts solution add 40 of water, and keep 
 the temperature at 110 24 hours. 
 
 CARMINE OR ROSE COLOUR. This beautiful 
 colour requires much attention in its preparation to 
 secure all the possible brilliance of tint ; and in its 
 application, to prevent injury from excess of heat in 
 baking, or from the gas of either carbonic or sulphur- 
 ous acid. The colour is prepared by this process : 
 The solution of gold is brought into combination with 
 
 ammonia by any of the usual methods ; the muriate 
 
 2 M 
 
530 CHEMISTRY OF POTTERY. 
 
 of gold is decomposed by ammonia, or an ammonia- 
 al salt ; or it is kept in a dark and damp place 
 where the air is stagnant. Mons says : " I prepare 
 it with most advantage by precipitating, by potash, 
 a diluted solution of muriate of gold and muriate of 
 ammonia." In pure water at 190 Fahrenheit, 95 
 parts, and solution of gold 5, add sal ammoniac 
 until precipitation ceases ; then add a little more, 
 and let the liquid repose 48 hours. By siphon draw 
 off the liquid ; and when the colour is not im- 
 mediately wanted, wash it in great excess of boiling 
 pure water, and again let it repose 48 hours. It is 
 best dried on bibulous paper on a plaster slab, and 
 a feather will brush it off the receptacle.* 
 
 This preparation is fulminative, and will explode 
 most violently and dangerously, because of the 
 presence of the fulminic acid, when the temperature 
 is raised to 420 Fahrenheit, a little lower than that 
 at which tin fuses, and also by moderate friction ; 
 but the presence of a fixed alkali neutralises the 
 acid, and exposure to a heat of 212 some hours 
 will adapt the colour for being applied with safety. 
 No acid or alkali will decompose this salt, the oxide 
 possessing the potency of an acid, and the ammonia 
 that of an oxide. 
 
 Another preparation of gold, more easily and 
 
 * I have noticed what I deem something remarkable, that by 
 precisely pursuing the manipulations mentioned in many pub- 
 lished formulae, the colour-maker will not be able to supply the 
 colours of which they profess to be recipes. They merely mention 
 a part of those which must be performed, and leave them to 
 suggest the remainder, for the person himself to discover if he be 
 .able. 
 
COLOURS. 531 
 
 with safety managed, and for many uses of equal 
 strength, is the brownish-yellow (not fulminative) 
 precipitate, by adding carbonate of potash to the 
 diluted solution of gold when the aqua regia is one 
 of those already mentioned, and free from ammonia. 
 
 COLOUR. Mix precipitate 75, chloride of silver 25 
 parts ; then grind colour 14 with flux (22) 86 parts. 
 (The flux will depend much on the glaze.) At first 
 the colour seems a dirty violet, but baking renders it 
 a beautiful carmine. On all soft porcelains, and with 
 all artists, this and the purple cannot be changing 
 tints ; but it alone changes on hard porcelains, because 
 of baking. The pernicious effects of fire preclude the 
 formation of the basic oxide and the flux or solvent 
 into a frit prior to using. (See the Reds from Iron.) 
 
 PURPLE.* To gold solution 80 parts, tin solution 
 
 * This colour, the most celebrated, and brought to the greatest 
 perfection among the ancients, was accidentally discovered about 
 1,735 years before the Christian era. Poetry has wrapped her 
 embellishments around the facts, which appear to be these : One 
 of the shepherd kings of Phoenicia, whom some name the Tyrian 
 Hercules, was traversing the strand, accompanied by his dog, 
 which was incited by hunger to devour some shell-fish. The 
 mouth became stained of a beautiful colour by the liquid ; and 
 the owner's attention being excited, this led to trials of the effect 
 on woollen fabrics, and the success surpassed all his expectations. 
 His devotedness to the interests of his country, equal to that of a 
 lover to his fair one, caused him to restrict its use, on pain of death, 
 as symbols of power and of office, only to the chief priesthood and 
 royalty ; and he employed every effort to secure the revenue to his 
 own city, and preclude depreciation of the article. I need not 
 more than just hint at the great oversight of persons who give 
 the person and date, Phoanix, second king of Tyre, 500 B.C., when 
 Hiram was king more than 1000 years B.C. The black, yellow, 
 blue and green colours Alexander the Great brought from India. 
 
 2 M 2 
 
532 CHEMISTRY OF POTTERY. 
 
 (2) 20, and silver solution 1 part, add of pure water, 
 at 200 Fahrenheit, 800, 200, and 10 parts respec- 
 tively. First mix well the solutions of gold and 
 silver ; over the liquid with a feather sprinkle a 
 solution of caustic potash, which at intervals repeat 
 cautiously, else peroxide of tin will be formed ; then 
 stir very carefully with a strong feather the liquid 
 while pouring in the solution of tin, and while any 
 precipitate appears continue adding pure boiling 
 water, and let the whole repose forty-eight hours. 
 To brighten the tint, wash the purple in dilute 
 nitric acid, and a portion of the tin will be solicited, 
 and can be filtered out. The precipitate 25 parts 
 with 75 of flux 10 ; or 20 parts with 80 of flux 8 ; 
 or 18 parts with 88 of flux 14 ; or 20 parts with 10 
 white oxide of antimony and 78 of flux 10. 
 
 Another formula is gold solution 47, tin solu- 
 tion 47, silver solution 6 ; and the precipitate 25 
 parts with 75 of flux 4. 
 
 Purple Distance. The gold precipitate 22, 36, 
 very clean oxide of manganese 15, 18, and 63, 46, 
 of flux 10. 
 
 Unnumbered have been the failures in the pre- 
 paration of this beautiful colour, and very probably 
 because of the difference of opinion with reference to 
 its chemical components. One of the first authorities 
 of the age, Dr. Thomson, considers that it is formed 
 " by dropping a solution of gold into a solution con- 
 taining both the oxides of tin. When dropped into a 
 solution of protomuriate of tin, it is a dark brown, 
 without any beauty. We must have both oxides in 
 the solution to ensure the fine purple of Cassius." 
 Now, I beg to remark, that here appears a complete 
 
COLOURS. 533 
 
 oversight of the complete difference between precipi- 
 tating tin by gold and gold by tin. The doctor also 
 says : "It has been supposed that this beautiful colour 
 is owing to the presence of an oxide, between the nib 
 and per oxides, of whose existence no satisfactory evi- 
 dence has been adduced. But the observations of 
 Proust, together with those of Marcadiew (Ann. de 
 Chimie, etc., XXXIV., 147), seem to leave no doubt 
 that the gold in this beautiful powder is in the metallic 
 state." Even if this be the fact, does it remain so in 
 the tints it supplies to glaze and enamel ? And is not 
 this supposition of the combination of metallic gold 
 with the peroxide of tin contrary to every known 
 analogy of the combination of metals with oxides ? 
 There is great probability in the following opinion : 
 One oxide of gold, g. 1 + 1 ox., always forms green 
 or yellow combinations, and has present only one-third 
 the supply of oxygen in the other, g. 1 + 3 ox. , which 
 forms the rose-colour. Now, as opposite tints result 
 from these two states of oxidation, the opinion is in- 
 duced that for the forming of the purple it needs a 
 less degree of oxidation of the gold than the rose- 
 colour ; the deutoxide, because not salifiable, is not 
 discovered, as are the others, and yet it will with the 
 oxide of tin form a compound, solicited by ammonia 
 to solubility, proving it an oxide. The purple needs 
 this deutoxide, and cannot exist without it, and the 
 numerous failures have been from attempting this 
 with the other two oxides. In fact, as Berzelius says : 
 " The oxides g. 1 + ox. and g. 1 + 3 ox. combine with 
 acids, while the oxide g. + 2 ox. does not combine 
 with other bodies, though it has an affinity with other 
 oxides." 
 
534 CHEMISTRY OF POTTERY. 
 
 The tin solution (1) has the metal in the state of 
 per-muriate, from whose employment in forming the 
 purple have resulted numerous disastrous, vexatious, 
 and most expensive failures in the processes, and when 
 the ware was baked. The solution (2) or (3) contains 
 the tin in proto-muriate, regarded as that only proper 
 to be a component of the potter's purple. If Dr. 
 Thomson be correct, then certain proportions of each 
 must be used for the purpose. 
 
 An opinion is current, that by mixing the very 
 dilute solutions mentioned, every two parts of gold 
 will supply eleven of purple. The quantity of solvent 
 it will appropriate proves the colouring power of the 
 purple, compared with flint-glass, as 1000 to 1 ; and 
 as 12 to 1 is that of the oxide used in the carmine 
 to the purple. Other different preparations of gold, 
 without the presence of an atom of tin, will supply a 
 fine purple ; proving the tin not essential or indispen- 
 sable to purple enamel colour, as it has very slight 
 colouring power, therefore does not add to the basis 
 of the colour. Its precise use is its peculiar property 
 of adapting the purple, of which it is an ingredient, to 
 retain its indispensable dose of oxygen, while sustain- 
 ing the duration of a higher temperature of the baking 
 process, requisite to be appropriated by the glaze ; it 
 also renders the gold refractory at a very high tempe- 
 rature, while the solvent preserves the proper state of 
 oxidation. The purple is most advantageously applied 
 to a surface whose vitrification dissolves the oxide as 
 quickly as it is formed, precluding the reduction, and 
 the purple continues firm until dissolved by very high 
 temperature. Upon the perfect manner of perform- 
 ing the processes of enamelling, mainly depends the 
 
COLOURS. 535 
 
 beauty of the manufactured article ; any irregularity 
 causing pain to the experienced eye, and much lia- 
 bility to greater injury attaching to the endeavour to 
 correct it. 
 
 As far as colours and materials are proper, we 
 possess the requisites for ensuring, to productions of 
 the pencil, whatever degree of immortality they de- 
 serve. And had the philosopher Davy only recol- 
 lected this fact, as referring to our best porcelain, he 
 would have qualified the expression used by him 
 when in Italy : "It is unfortunate that the materials 
 for receiving those works which are worthy of passing 
 down to posterity, as eternal monuments of genius, 
 taste and industry, are not imperishable marble or 
 stone." What are these when compared with the 
 hard porcelain ? And even the soft kinds will long 
 remain uninjured by extraneous atmospheric action. 
 
 When the purple powder 16 parts have 84 of 
 flux 18, a very beautiful VIOLET is produced by the 
 peculiar action of the lead present. 
 
 OTHER PURPLES. For flint ware, frit together 
 well-pulverised oxide of manganese 44, 48 parts, 
 zaffres 5, 8, red lead 51, 44; Lilac, manganese 38, 
 smalts 62. 
 
 Another Aqua Regia. When chromic acid and 
 muriatic acid are distilled by a gentle heat, chlorine 
 is produced ; and a chemical mixture of chromic and 
 muriatic acids forms an aqua regia which will dis- 
 solve gold. This potency, not possessed by any other 
 of the metallic acids, is supposed to be consequent 
 on the slight re-action of oxygen on the base. 
 
536 CHEMISTRY OF POTTERY. 
 
 REDS, etc., obtained from Iron. 
 
 The temperature to which oxide of iron is first 
 raised will cause the tint to be Rose-Red, or Brown, 
 of different shades ; yet, when properly prepared, un- 
 changeable on soft or hard porcelain. This rose-red 
 has been long known ; but either because when first 
 the painters on enamel commenced their labours on 
 porcelain they neglected to adapt their methods to 
 the different recipient, or because they feared it would 
 be evanescent like the carmine, it was not used with 
 the advantage of which it is susceptible. Though it 
 may be diminished in brilliance compared with the 
 carmine supplied by the oxide of gold, yet on a good 
 glaze of felspar, natural or artificial, it is changeless, 
 preserving a tint peculiarly fine and rich ; and com- 
 bined with the proper flux, No. 22, substituting 
 minium for flint, it is certain in application, and with 
 it roses have been frequently painted, which only 
 improved in brilliance by the baking. The beauty of 
 tint is supposed to result from imperfect vitrification, 
 which causes or allows the particles of the peroxide 
 to be in an extremely comminute state suspended in 
 the solvent or flux. 
 
 When the glaze has excess of oxide of lead (as 
 soft porcelain), there ensues a volatilisation of the 
 oxide of iron, by which its clearness is affected to a 
 dull disagreeable brick-red, as likewise from minus 
 of flux, or higher temperature. To supersede this 
 liability to change, a saturated solution of sulphate 
 of iron has alumine mixed carefully with it, and 
 afterwards test 3 is added until precipitation ceases. 
 
COLOURS. 537 
 
 I have already noticed (p. 489) the potency, as in 
 this instance, with which alumine solicits oxides. 
 
 1. In nitric acid 66 parts and pure water 34, dissolve clean 
 iron-filings ; dilute the liquid, and add test 4 till precipitation 
 ceases. This place on a sheet of iron, and by a bright fire bring 
 to a fine bright red. Colour, precipitate 30 parts and 70 of flux 9. 
 
 2. The precipitate (1) 34 parts mix with 66 of roasted table-salt, 
 which incandesce ; then mix well in boiling water in great excess, 
 and let it repose forty-eight hours ; by siphon abstract the water, 
 throw the sediment on a filter, and wash well with pure boiling 
 water. For .Rose-colour, precipitate. 25 parts with 75 of flux 9. 
 
 3. In a bright open fire calcine good sulphate of iron till there 
 remains the fine orange, or bright red peroxide of iron (not at a 
 very high temperature, else it will be brown, or cream-white) ; wash 
 well in plenty of boiling pure water to abstract the sulphuric acid, 
 then on bibulous paper dry the powder. For Colour. Enamel 
 Beds, calc 25, 30, with 75, 70 of flux 9. Light, calc 40 and 60 
 of flux 8. Brown, calc 15, 20 parts with 85, 80 of flux 22. 
 Flesh, perchloride of manganese (supplied by saturating muriatic 
 acid at 1-149 with black ozide of manganese, diluting with ten 
 bulks of pure boiling water, filtering, concentrating, and leaving to 
 repose for crystallisation), when dried and ground, use in equal 
 quantities with flux 22. Another is formed by a very dense solu- 
 tion, long evaporated, of clean sulphate of iron 28 oz., and 8 oz. of 
 gum Arabic kept close in a phial. Pink, mix and frit 12 to 18 
 hours oxides of chrome 35, 40, 45, of tin 40, 35, 30 with lime 25. 
 It is a compound of chromic acid 2, peroxide of tin 1, and lime 1 = 
 :25-75. Dark Brown, brown oxide of iron 34 with 66 of flux 22. 
 Light Brown, calc of enamel red 12, calcined umber 9, chrome 
 yellow 9, with 70 of flux 7. A small portion of oxide of iron raised 
 to a very high temperature to fully vitrify it with a large proportion 
 of flux or solvent supplies different shades of green to yellow. A 
 larger dose of oxide supplies a yellow by full vitrification ; and a 
 yet larger dose a brownish-black, that seems a very dense or con- 
 tracted yellow, as this tint results again from it by diluting the 
 previous dark colour with much of the solvent. The mixture of 
 varied proportions of the red and black oxides of iron will supply 
 the different shades of red, brown, chocolate, chestnut, etc. 
 
538 CHEMISTRY OF POTTERY. 
 
 BROWN-REDS and BISTRES are supplied from 
 the mixture of varied proportions of the black oxide 
 of manganese, brown oxide of iron, and oxide of 
 chrome, fritted with the components well determined, 
 and a certain quantity of the flux or solvent, and then 
 properly ground. This mode of preparing the brown- 
 reds prevents any change in the tint by baking, 
 whether used on soft or hard porcelain, the oxide of 
 manganese promoting the fusibility of the iron into 
 its yellow oxide, and counteracting the potency of 
 the lead in the glaze to destroy the tint of the iron, 
 already noticed. (See p. 499, note.) 
 
 Bed-brown. Frit two hours peroxide of manganese 67, 75, 
 brown oxide of iron 13, 15, oxide of chrome 20, 10 ; then colour 
 50 with 50 of frit 8, fuse other two hours. Brown for biscuit. 
 Frit two hours oxide of manganese 56, 60, 65, brown oxide of 
 iron 24, 20, 20, oxide of chrome 20, 20, 15 ; then of colour 35, 
 44, 56, with 65, 56, 44 of flux 7, fuse other two hours. Mulberry, 
 for biscuit. Brown 95, 92, 90, zaffres 5, 8, 10, grind well for use. 
 For Grounds. Brown-red, russet, and tortoise-shell. Mix brown- 
 red colour 30 with 70 of flux 10 ; 36 with 64 of flux 7 ; 35 with 
 65 of flux 20. 
 
 Whenever bitartrate of potass or tartar is introduced as a 
 component of certain colours, considerable care is needful, 
 because the escape of the carbonic acid gas creates a very violent 
 effervescence, which may carry into the fire some of the metallic 
 oxide, the base of the colour, and occasion a proportionate loss of 
 metal, and consequent weakness of tint. Some persons substitute 
 fresh burned and well-dried charcoal, incandesced in a covered 
 crucible, and then added to the frit. A remedy for the efferves- 
 cence seems offered in the practice of the bottle-glass makers : 
 Cast in a little water, this will decompose ; its oxygen will com- 
 bine with the carbon, and as carbonic acid gas it will be dissipated 
 by the intense heat ; the frit will continue sluggish until the 
 whole process is finished. 
 
COLOUES. 539 
 
 BLUES. 
 
 IT is well known that cobalt supplies the best 
 test of the presence of alumine in an assay. We 
 therefore need not be surprised, but might naturally 
 expect, that preparations of oxide of cobalt would 
 supply blue tints to a silicate of alumine, more rich, 
 solid, fine, and fixed, whatever might be the degree of 
 temperature to which the baking is raised ; and the 
 Manufacture of porcelain and flint wares established 
 the supposition. Certainly the components of the 
 wares, body as well as glaze, will affect the tint, how- 
 ever excellent the colorific oxide ; but mostly the 
 varied shades and gradations of excellence are caused 
 by the presence of ingredients introduced from 
 motives of cupidity. Whenever the lines of the 
 design are smeared, instead of being clear and distinct, 
 there is great probability that the presence of arsenic 
 acid has caused the volatilisation of the cobalt at a 
 heat lower than would have been requisite had it 
 been pure oxide. 
 
 In obtaining the oxide, each blue-maker follows 
 his own processes, usually some modification, accord- 
 ing to circumstances, of the following : 
 
 Take cobalt metal 45 parts, carbonate of potash 45, charcoal 6, 
 Lynn sand 4 ; or 40, 40, 6, 14 ; or 50, 40, 5, 5. Mix well, and 
 with it half-fill skittle-shaped crucibles ; place these in a muffle, 
 or a reverberatory furnace, gradually raise the heat five hours, keep 
 the temperature steady three hours longer, and gradually diminish 
 for eight hours. When cool, the upper stratum in each crucible is 
 cobalt oxide with a silicate of potash ; the lower is an alloy of 
 nickel and bismuth. Pulverise the silicate and mix 90 parts 
 with 10 of potash. Of this mixture, into a pint flint-ware 
 
540 CHEMISTRY OF POTTERY. 
 
 biscuit-flanched jar, put 1 pound ; raise the temperature four 
 hours, keep it steady three hours, and lower it gradually six hours 
 more. This process must be repeated until the colour seems very 
 pale. Pulverise the calc ; and to dissipate any arsenic present, 
 which fusion will not, on a layer of dry flint-powder spread the 
 calc, and calcine during six hours, which will also separate the 
 nickel. Some persons next mix cobalt 90, flint 6, and borax 4 ; 
 others mix 85, 9, and 6 of potash. 
 
 Mix equal weights of zaffre and potash, which put into cups 3 
 inches diameter, 1^ high, and -J- thick ; place in the muffle, raise 
 the temperature as last directed. The upper stratum will be blue 
 calc, the lower nickel and scoria. The nickel, when a sufficient 
 quantity is accumulated, is pulverised, and to the metal 80 parts, 
 add plaster 12, potash or borax 8, and in strong cups fuse at a 
 high temperature during 16 hours. 
 
 For the colour, strong, cobalt 40, 35, 30, 25, 20, with 60, 65, 
 70, 75, 80 of flux 7, or 13 ; weak, cobalt 25, 20, 15, with 75, 80, 
 85 of flux 22. For painting, cobalt 25, 20, 30, with 75, 80, 70 of 
 flux 8, or 14. MATT-BLUE, cobalt oxide 60, zinc 15, lime 25, or 
 65, 15, 20 ; for use, mix colour 35 with 65 of flux 22. 
 
 The following has been forwarded by an anonymous corres- 
 pondent, who thinks it entitled to attention, as Westrumb, from 
 whom it is stated to be copied, is of admitted celebrity : By some 
 convenient method carbonise animal oil, to which add soda or 
 potash, and incandesce for 30 minutes ; then mix this, as 25, 30 or 
 35 parts with 8, 12, or 16 of alum, and 67, 58, 49 of sulphate of 
 iron, which frit two hours ; and when cool, take of frit 40 parts 
 and mix with 60 of this solvent (frit), well-dried sulphate of soda 
 50 parts, Lynn sand 35, and 15 of charcoal powder. The state- 
 ment suggests this as an approach to the blue employed by the 
 ancients on their beads, on whose peculiar processes no record is 
 known to remain. Brongniart says : "The pure chromate of lead, 
 on porcelain very highly baked, supplies a very deep and fixed blue 
 of considerable beauty." And, according to Kuhlman, the like 
 result is obtained from calcining sulphate of soda 12 hours in 
 a reverberatory furnace. Another process is : Ultramarine. 
 Carefully mix china clay 25 parts, flowers of sulphur 37, and pure 
 dry sub-carbonate of soda 38 ; in a coated porcelain retort raise 
 the temperature gradually until all vapour ceases to escape ; the 
 spongy result at first reflects a green tint which the action of the 
 
COLOURS. 541 
 
 atmosphere changes into blue ; pulverise, and wash out all the 
 sulphur possible, decant the liquid, dry the powder, calcine to a 
 cherry red, to dissipate the sulphur, and the remainder is a good 
 blue, though not very intense. The mixture of saturated solu- 
 tions of cobalt and alum, precipitated by test 1 or 3, also those 
 of carbonates of zinc and iron saturated with cyanogen gas (from 
 cyanodide of mercury), and precipitated by test 4, will produce 
 fine Blues, but some attention is needful in the baking. 
 
 "A print is the translation of a picture, legible 
 to every eye, and current in every country ; distribu- 
 ting the admirable productions of Art into the hands 
 of thousands, who, but for engraving, must have lived 
 and died in ignorance of their worth, because unac- 
 quainted with their merits." 
 
 The discovery of printing from plates of metal 
 is assigned to a goldsmith of Florence, named THOMAS 
 FINIGUERA, about the middle of the fifteenth century. 
 This ingenious man, having finished some ornamental 
 work in which engraving was employed, and having 
 filled the strokes with a black substance to render 
 them conspicuous, while examining the effect pro- 
 duced accidentally let fall on it some of the melted 
 wax of the taper which lighted him. This quickly 
 hardened on the cold metal, and when chipped off 
 its interior surface was observed to present a correct 
 transcript of that part of the engraving on which it 
 previously had fallen. This suggested to Finiguera 
 the idea of obtaining by some method, impressions 
 of engravings on paper, and he was not long in suc- 
 cessfully realising the object of his research. 
 
42 CHEMISTRY OF POTTERY. 
 
 YELLOWS. 
 
 YELLOWS, as much as any of the other colours, 
 are improved in quality and permanence by the 
 methods of preparation suggested by the improve- 
 ments in chemical processes. When the quantity of 
 oxide of lead present in the colour, and also in the 
 glaze, was so great that seldom could the most care- 
 ful mixture of other ingredients and management of 
 the processes prevent a portion being de-oxidated, 
 and appearing in black specks on the glaze, the tints 
 of the oxides of iron were so affected also by the 
 oxygen evolving, as frequently to present, after bak- 
 ing, merely a faint outline, instead of a well-defined 
 figure. The substitution of chromic acid for carbonic 
 increases both the brilliance and permanence of the 
 tint ; while the introduction of the natural or artificial 
 felspar glaze, because of its alkaline properties, has 
 facilitated its application. None of the ancient 
 yellows was so durable, brilliant, and beautiful as 
 this chrome yellow ; superior to preparations of oxides 
 only, as this insoluble salt, resulting from chemically 
 combining a metallic acid with a metallic oxide. 
 
 Upon glazed flat dishes expose iron filings sprinkled with 
 water, to be oxidated by the action of the atmosphere. After 24 
 hours, constantly, wash off the oxide into a foot-bath well-glazed. 
 The water draw off by siphon, and again use to wash off the oxide. 
 When the oxide is needed, let the repose be 48 hours, then draw 
 off the water, as before, and on bibulous paper dry the precipitate ; 
 then put it into a crucible, cover close up, and incandesce 4 hours 
 for a bright tint, and 6 to 8 for one darker. For use, colour 35, 
 chrome yellow 10, and 55 of flux 12. Chrome yellow. To dilute 
 solution of nitrate of lead, add solution of chromate of potash until 
 
COLOURS. 543 
 
 precipitation ceases ; then leave to repose 48 hours, by siphon 
 decant the water, and dry the precipitate. Or, saturate a pint of 
 pure water by acetate of lead, and add 16 oz. of carbonate of 
 barytes ; boil, and stir in half an ounce of chromate of potash ; 
 after 24 hours' repose decant the water, and dry the colour for use. 
 Frit for 2 hours chromate of iron 70, pearlash 30, or 80, and 
 nitrate of potash 20 ; add water, and keep at 212 till all the frit is 
 in solution ; then add solution of acetate, or nitrate of lead ; repose 
 24 hours, then filter for use. Nasturtium. Iron precipitate 10, 
 chrome yellow 20 parts with 70 of flux 10. Orange, biscuit. 
 Frit 3 hours brown oxide of iron 26, 30, 35, antimony 74, 70, 
 65, and about 4 of tin ash. Colour 40 with 60 of flux 1, 2, or 3. 
 For Enamel, substitute the red for the brown oxide of iron. 
 Base yellow. Frit 3 hours antimony 17, 10, 36, 10, litharge 17, 
 10, 48, 15, tin ash 33, 40, 16, 45, lead ash (or white lead) 33, 40, 
 0, 30. Frit minium 80, sal ammoniac 20. 
 
 The minium or red oxide of lead is mostly em- 
 ployed by the colour-maker, because scarcely can 
 it be adulterated ; and next in genuine quality is 
 litharge, the brown oxide ; whereas the other, the 
 white oxide, is readily mixed with Dutch lead, sul- 
 phate of barytes, the detection of which requires 
 careful analytical processes. Unless the materials be 
 genuine, there will result considerable loss. And 
 even when they are, the most sedulous attention to 
 the rise and duration of temperature, as well as the 
 precise proportions of components, are indispensable. 
 Hence the advantages possessed by a person with ade- 
 quate capital, who, preparing a large quantity of the 
 colour, secures the peculiar tint for his customers. 
 Was the test of difficulty the unsuccessful attempts 
 to excel in this department, we might conclude that 
 the enamel purple, and printing pink, red, brown, 
 and green, are among the most rare productions, 
 which require all the skill and judgment of practice, 
 with the investigations of science. 
 
544 CHEMISTEY OF POTTEEY. 
 
 GREENS. 
 
 THE colours with this tint now generally ac- 
 cepted, are preparations of chrome, which without 
 injury sustains any temperature to which it may be 
 requisite to raise the ware. Their preparation also 
 is less liable to mutability than those from oxide of 
 copper, or from mixture of yellow and blue, which 
 need fritting with their solvent or flux before grind- 
 ing to capacitate them to bear high temperature,, 
 without the tint becoming black. 
 
 Green Oxide of Chrome. Slowly raise to a state of incandes- 
 cence a mixture of chromate of lead and oil, and when metallic 
 globules appear, quickly raise the temperature much higher ; leave 
 the crucible to gradually cool ; the upper stratum will be green 
 oxide, the lower the lead in its reduced state. Colour 40 with 60 
 of flux 23. Another process is mix saturated solutions of chro- 
 mate of potash and nitrate of mercury. The reciprocal potencies 
 of the substances combine to form fresh compounds, chromate of 
 mercury and nitrate of potash. This latter is washed out of the 
 filtered precipitate by boiling pure water; the powder is then 
 brought to a very high temperature of 500 to volatilise the mer- 
 cury, cause part of the oxygen to evolve, and leave the pure green 
 oxide. Colour 35 with 65 of flux 21. Boil a saturated solution 
 of chromate of potash, to which add alcohol 12, and sulphuric 
 acid 13, per cent. ; repose 12 hours, filter out and incandesce 
 the beautiful green hydrate of chromium. The solution of 
 chromate of potash, at 120 Fahrenheit, carefully treat with 
 either test 2, or 7 ; the former let repose 24 hours, and filter out ; 
 the latter evaporate dry, for use. A saturated solution of a 
 muriate, acetate, or arsenite of copper, treat with a solution of car- 
 bonate of potash ; and when the precipitate becomes sluggish, let it 
 fall into a separate vessel. The tint obtained from the latter is 
 olive, dull, and dense ; that from the former is brilliant and clear. 
 The shades vary because of the acid present with the salt. The 
 fluxes are Nos. 3, 4, 5. Emerald. Frit oxide of chrome 50, 
 oxide of nickel 35, nitre 15. Colour, frit 35 with 65 of flux 9. 
 
COLOURS. 545 
 
 Brongniart says, " oxide of nickel 80 and nitre 20 parts supplies 
 the emerald green of the Sevres porcelain, and uninjured will bear 
 any degree of heat. " Olive. Frit oxide of nickel 65, zaffre 35. 
 Or, chromate of lead 80, potash 15, arsenic 5. Colour, equal 
 weights of frit and flux 12. Celeste. Frit 2 hours chromate of 
 lead 35, 42, 49 ; oxide of zinc, 5, 7, 10 ; zaffres 40, 51, 41. Most 
 brilliant on a glaze of artificial felspar, on soft porcelain. Blue. 
 Frit 3 hours brown oxide of copper 65, 72 ; yellow oxide of iron 
 35, 28. Colour, frit 35 with 65 of flux 20. 
 
 Mineral Greens. Dissolve to saturation sulphate 
 of copper in hot water, and while hot add saturated 
 solution of carbonate of potash ; also carbonate of soda, 
 sulphate of magnesia, sulphate of iron or potash, 
 sulphate of alumine, and the two last precipitate with 
 bi-carbonate of potash. The precipitated basic car- 
 bonate of copper filter and wash, then dry. 
 
 In a solution of potash boil white arsenic, and 
 this arseniate of potash, added to a solution of sulphate 
 of copper, produces a green precipitate of arseniate 
 of copper ; filter, wash with pure cold water, and dry. 
 Scheeles Green. Filtering each solution prior to 
 mixture greatly improves the resulting colour. Also 
 adding 15 per cent, of acetic acid, and instantly 
 throwing the liquid on the filter, will supply a diffe- 
 rent yet very beautiful green. 
 
 Vienna Green. In pure vinegar, heated in a 
 copper vessel, dissolve verdigris to saturation ; then 
 add solution of white arsenic an equal quanity ; add 
 vinegar till all the precipitate is re-dissolved ; distil 
 till a fine green crystalline precipitate falls ; filter, 
 wash, and dry for use. When copper remains, add 
 more arsenic ; when arsenic, add more copper, till 
 the mother-liquor is rendered inert. Prior to distil- 
 lation, adding 10 per cent, of potash or of lime, car- 
 bonated, will much alter the resulting colour. 
 
 2N 
 
546 CHEMISTRY OF POTTERY. 
 
 BLACKS. 
 
 BLACKS of the greatest beauty and brilliance are 
 now supplied in lieu of those which had been trouble- 
 some and uncertain. But as no metallic oxide, 
 pet- se, supplies a black sufficiently dense for porce- 
 lain platinum best, manganese next, while that of 
 iron fails, blisters, is dull, opaque, and easily becomes 
 reddish, and as lead glazes caused the enamel 
 blacks to scale off, or lose their brilliance the gene- 
 ral practice is current of chemically combining (not 
 merely mixing) several oxides, as manganese, cobalt, 
 nickel, iron, and chromium, which supply a brilliant 
 colour for alkaline glazes. I have already remarked 
 that the components of the biscuit often much affect 
 the colours. In blacks this is very obvious. 
 
 Frit 2 hours black oxides of manganese 38, of iron 36, zaf- 
 fres 26. Colour 45 with 55 of flux 22. This is the black of the 
 Sevres porcelain. Frit black oxide of manganese 40, 50, 50, 
 oxides of chromium 10, 12, 15, of iron 8, 12, 15, of nickel 10, 6, 2, 
 and zaffre 32, 20, 18 ; the combinative potencies of the manganese 
 and cobalt are remarkably obvious when fritted together; for, as 
 with alumine, complete combination ensues, and the result is a 
 deep black. Colour, equal weights of frit and flux 23. For 
 enamel. Frit 2 hours manganese 32, 30, zaffre 16, 20, brown 
 oxide of iron 24, 20, nickel 2, 4, oxide of chromium 8, 10, 
 copper 12, 14, nitre 4, 0. 
 
 General Black Flux. Ignite nitrate of potash 1, bi-tartrate of 
 
 potash 2. 
 
COLOURS. 547 
 
 PURE WHITE. 
 
 THE preparation requires operose processes to 
 secure a clear tint, with a body sufficiently fusible to 
 readily bake with any glaze. Also the precise pro- 
 portions of the components require to be accurately 
 stated. 
 
 In pure water at 120 dissolve 16 oz. of good table-salt, filter, 
 evaporate partially, and crystallise for the square crystals, or dry 
 and decrepitate the salt. Into a red-hot crucible put a determined 
 weight of grain tin, and when fused, add twice the weight of the 
 salt, or thrice of the crystals ; closely cover, often stir with a red- 
 hot spatula, and when it is of a white heat, keep the temperature 
 up 80 to 90 minutes ; cool, pick, pulverise, and raise the tempera- 
 ture during 3 hours ; cool, pulverise, with great excess of boiling 
 water wash out all the salt, let both repose 24 hours, then by 
 siphon draw off the water, and dry the precipitate for use. An- 
 other. Kunkel, Neri, and some others, direct to frit tin 55 with 
 red lead 45 ; then for 10 hours alloy 58, flint 58, tartrate of 
 potash 4. Again, frit for 3 hours calc 80, with 20 black oxide 
 of manganese ; pulverise, wash well in cold water, and repeat 
 the process of calc and manganese until the residuum becomes 
 fine and perfectly white. 
 
 General White Fluxes. Into a red-hot crucible project : 
 
 1. Nitrate of potash 1, and bi-tartrate of 
 
 potash 1. 
 2. Dried common-salt 4, dry lime 4, fluate 
 
 of lime 2, charcoal 1. 
 
 3. Calcined borax 40, lime 4, charcoal 5. 
 4. Glass powder 4, borax 2, charcoal 1. 
 2 N 2 
 
548 CHEMISTRY OF POTTERY. 
 
 SILVER for Egyptian, or to Burnish. 
 
 BY polished copperplate immersed 24 hours 
 precipitate silver from a dilute nitric solution ; filter, 
 wash well, dry, and to silver 80 add 20 of good 
 ceruse. By clean iron filings precipitate the copper 
 for a rich bronze. Another As silver is affected by 
 yapours, black when sulphur is present, and tarnished 
 ;foy the atmosphere, cannot be used in extreme com- 
 minution, nor traced very fine and thin, Klaproth 
 suggests a substitute in platinum, free from any of 
 these inconveniences. In aqua regia 2 dissolve 
 platinum, add test 34, filter, wash well, evaporate 
 dry, and incandesce, to dissipate the precipitant ; to 
 the powder 35 add 65 of flux 23 ; use with oil of 
 spike, bake and burnish. When platinum 35 with 
 65 of gold are used, the silvery brilliance on a con- 
 vex surface covered thrice, and carefully baked, 
 excels that of a polished steel mirror. 
 
COLOUKS. 549 
 
 GOLD for Burnishing. 
 
 THERE is requisite much care and attention, be- 
 cause great difficulties often occur in not properly 
 managing the gold in these processes, to provide 
 antidotes against its deoxidation by sulphuretted 
 hydrogen, carbonaceous vapours, or extreme rise of 
 temperature ; and yet secure that comminution of its 
 particles that peculiarly adapts it, with a certain pro- 
 portion of solvent or flux, for economical application 
 to the glaze with which it is required to combine. 
 
 Mix solutions of gold 75 and 25 of silver, to which add 900 of 
 pure water at 212. Carefully stir while adding a saturated solu- 
 tion of proto- sulphate of iron, till precipitation ceases ; add a little, 
 and let it repose 24 to 48 hours ; by siphon draw off the water, 
 wash well, dry on bibulous paper, and mix borax at pleasure for 
 use. Or, mix solution of gold 77 with 33 of silicate of potash ; add 
 test 26, till precipitation ceases ; allow repose, filter, wash, dry, and 
 use metal 10, flux 90. Or, the solution of gold evaporate dry, wash 
 well in excess of pure water, raise the temperature to 130, add 
 test 1 till precipitation ceases, and let the orange precipitate repose 
 not less than 24 hours ; by siphon draw off the water, evaporate 
 the precipitate, and add flux as needful. Were the process re- 
 versed, the aciduline potency of the gold would with the alkali 
 form a blackish-brown result. Or, alloy gold 80 with oxides of 
 silver 13 and 7 of bismuth ; or gold 66 with 34 of mercury. Alloy 
 26, 30, to 74, 70 of black flux (33 nitre, 67 bi-tartrate of potash). 
 
550 CHEMISTRY OF POTTERY. 
 
 PRINTERS OIL. 
 
 BOIL during 2 hours linseed-oil, very carefully 
 removing whatever scum may be thrown up ; add 
 red lead, and burn off all greasy particles ; other 
 ingredients add as stated, to preclude coagulation ; 
 simmer 2 hours, and cool for use. The proportions 
 vary with different persons. 
 
 1. Oil 1 quart, red lead \ oz., oil of amber 1 oz., capivi balsam 
 1 oz., oil of turpentine 1 oz., Stockholm tar 1 oz., Barbadoes tar 
 
 1 oz. 2. Substitute Venice turpentine 4 oz., and oil of amber 
 4 oz. for the oil of turpentine. 3. Linseed-oil 1 pint, Stockholm 
 tar \ pint, rosin 2 oz. 4. Oil 1 quart, tar 2 oz., balsam of sulphur 
 
 2 oz., Venice turpentine 1 oz. 6. Oil 1 quart, rape-oil 1 pint, 
 (or }), capivi balsam 2 oz. (or 1), pitch 1 oz., amber oil \ oz., 
 ceruse ^ oz. (or tar \ oz., balsam of sulphur 1 oz.). 6. Linseed- 
 oil 1 quart, flowers of sulphur 4 oz., balsam of sulphur 4 oz., 
 rosin 2 oz. 7. Linseed oil 1 quart, red lead 2 oz., balsam of 
 sulphur and Barbadoes tar, of each 4 oz., and \ an oz. each of 
 capivi balsam, oil of amber, acetate of lead and rosin. 
 
COLOURS. 551 
 
 LUSTRES. 
 
 Gold. In an earthen jug put balsam of sulphur 
 (oil of turpentine 86, flowers of sulphur 14 parts), 
 then raise the temperature to 200, and continue 60 
 to 80 minutes. When cool, add by measure, to 
 every 60 parts, 40 more of oil. Over a slow fire 
 again raise the temperature, and carefully stir therein 
 95 per cent, of the gold solution, and 5 per cent of 
 the tin solution. This gives the purplish tint to the 
 gold lustre. Solid Gold Lustre. On a well-glazed 
 plate with fat oil mix up a certain weight of the gold 
 precipitate (see p. 506 7); raise the temperature 
 till the oil is fluid, then add oil 25 parts, reduce the 
 temperature and add turpentine 75 parts. 
 
 New Lustre. The process is With gold lustre 
 first form the pattern and bake the ware ; next take 
 gold solution, and with a feather cover the pattern ; 
 this last cover with a saturated solution of sulphate 
 of iron, which precipitates the metallic gold on the 
 pattern ; wash well in water, and bake at about 600 
 Fahrenheit the fusing point of lead. 
 
 Silver. This lustre is prepared by a process 
 much different. Dissolve good platinum in aqua 
 regia at a raised temperature ; gradually add to this 
 solution thrice its quantity of spirits of tar, and avoid 
 the gas which evolves while the acids are being dis- 
 sipated. The platinum remains in the fluid ; and, 
 for use, this is evaporated to proper consistence. 
 
 The glaze for silver lustre usually has much 
 oxide of tin present with the other materials, from 
 the combinative potency with the oxide of platinum 
 tending to improve the clear bright metallic tint of 
 the lustre. 
 
552 CHEMISTRY OF POTTERY. 
 
 How Nature should have proceeded in a certain 
 mode of combination for substances and for colours, 
 agreeably to determined laws which human research 
 has developed, and from which she never departs, 
 can be adequately explained solely by the admission 
 of a " GREAT DIRECTING MIND ! " 
 
 Whatever contributes to the beauty of another 
 object to a certain extent partakes of that beauty ; 
 because the relative forms, and the particular con- 
 formity, reciprocate the beauties, although one may 
 be negative, or even uncomely. In the employment 
 of iier colours, Nature is lively by contrast solely, and 
 by the judicious arrangement displayed ; their oppo- 
 sition manifests her operations, and communicates to 
 the results life, fire and the greatest eclat. Most of 
 the tints she uses are composed of many colours and 
 shades, and seldom can we find in flowers, shells, or 
 animals, colours of only two components. Seldom, 
 also, is a fine tint left without being contrasted by one 
 obscure ; and these latter, in most instances, become 
 interesting by this contrast to colours truly rich, and 
 with which those obscure are thus assorted. Yet 
 with what inimitable skill does she accomplish this 
 contrast of her tints, and the proportion of her lights 
 and shades ; and the nearer the approach to these by 
 the imitations of our artists, the greater will be the 
 excellence of their productions ; whether to delineate 
 the different dyes of fruits in our gardens, the varied 
 hues in our plantations, and the diversified shades in 
 our fields ; whether to attempt a resemblance of the 
 velvet white of the lily, the delicious purple of the 
 violet, the rich crimson of the amaranth, or the 
 glowing blushes of the rose. 
 
COLOURS. 553 
 
 Kunckel gives these as the true components of the 
 colours used in the 17th century at the Delft and other 
 Dutch Manufactories, which doubtless have suggested many 
 useful hints to subsequent Manufacturers : 
 
 Black red -lead 50, iron-filings 19, copper-ashes, ces 
 ustum 19, zaffre 12. 
 
 Blue frit thrice, and throw cool into water red-lead 
 or lead-ashes 14 (Lynn) sand or dry flint-powder 30, 
 common salt 28, white calcined tartar 14, cullet 7, zaffre 7 ; 
 the duration of the final fritting determines the fineness 
 of the tint (K. says 2 days). 
 
 Or tartar 65, red-lead 17, dry flint 16, zaffre 2. 
 
 Or tin-ashes 6, lead-ashes 6, tartar 6, cullet 6, zaffre 10, 
 dry flint 33, salt 33. 
 
 Or red-lead 20, zaffre 20, sand 60. 
 
 Violet tartar 35, red-lead 18, dry flint 45, manganese 2. 
 
 Brown frit red-lead 7, dry flint 7, manganese 1. 
 Or red-lead 92, manganese 8. 
 
 Or (for a white ground) twice manganese 50, red- 
 lead 25, cullet 25. 
 
 Flesh-colour lead-ashes 92, cullet 8. 
 
 Gold colour frit litharge 75, sand or dry flint 25, 
 grind fine, dry, with nitrate of silver form a paste ; in a 
 crucible gently raise the temperature and form a green glass ; 
 grind with beer and apply to the well-heated ware ; in the 
 muffle cause the glaze to flow (and, says Heinsius, afflare 
 debes fumum), let them cool amidst the vapour of burning 
 vegetables (Phil. Trans. 465, Sect. 6). 
 
 Or (five times) saffron of Mars 1, red-lead 3, anti- 
 mony 2. 
 
 Or red-lead 40, antimony 40, iron-scales 20. 
 
 Or red-lead 48, flint 36, yellow ochre 6, antimony 
 6, cullet 4. 
 
 Or (transparent) twice red-lead 48, dry flint 48, 
 iron filings 4. 
 
554 CHEMISTRY OF POTTERY. 
 
 Green frit litharge or red- lead 40, cullet 40, brass 
 or copper-filings 20. 
 
 Or litharge 45, tlmt 50, copper-ashes 5. 
 
 Or (fine) Bohemian fluor spar 25, copper-filings 25, 
 red-lead 25, cullet 25. 
 
 Or frit the other components, and grind with half 
 the weights of Bohemian fluor. 
 
 Sea-green frit lead-ashes 48, tin-ashes 10, flint 26, 
 salt 7, tartar 4, copper-dust 5. 
 
 Iron ditto lead or red-lead 44, sand or flint 44, 
 copper calc 12. 
 
 Liver ditto litharge 48, salt 24, flint 24, manganese 4. 
 
 Purple-brown frit lead-ashes 30 (or red-lead), sand 
 or flint 36, manganese 3, cullet 30, zaflre 1. 
 
 Red frit litharge or red-lead 43, antimony 43, iron- 
 rust 14. 
 
 Or red-lead 50, antimony 32, saffron of Mars 18. 
 
 Yellow frit four times red-lead 43, glass of anti- 
 mony 29, tin-ashes 28 (or 33, 33, 34). 
 
 Or lead-ore 45, litharge of silver 10, sand 45. 
 
 Or (fine) red-lead 45, brick-dust 18, sand 9, white- 
 glaze 9, antimony 19. 
 
 Or cullet 44, antimony 11, red-lead 33, iron-scales 
 12. 
 
 Or litharge 65, flint 30, iron-filings 5. 
 
 Or (light) red-lead 56, antimony 16, cullet 16, tin- 
 ashes 12. 
 
 Or (citron, in a glass-furnace, 108 hours), red-lead 
 40, antimony 13, red-brick-dust 47. 
 
 White-glaze frit thrice litharge or lead-ashes 50, 
 sand 29, salt 10, ashes 15. 
 
 Or sand 30, lead-ashes 45, wood-ashes 19, salt 6. 
 
 Or lead 66, tin 34. These frit, lead and tin-ashes 50, 
 flint 25 (or sand or cullet), salt 25, or 34, 33, 33. 
 
 Or (fine) five times red-lead 75, tin-ashes or putty- 
 powder 16, salt 9, or litharge 68, tin-ashes 23, salt 9. 
 
COLOURS. 555 
 
 All simple or compound colours, and all the tints produced by 
 Nature or Art, proper for the different kinds of printing, form an 
 -extensive catalogue, regarded only by certain external characters, 
 or their intensity. However Art, directed by the experience of 
 centuries, prescribes bounds to the consumption of colorific sub- 
 stances, by their limitation to bright, splendid, durable tints. 
 The following NOMENCLATURE OF COLOURS, for the primary and 
 compound tints, has been attempted, with reference first to the 
 'Colours of Minerals least evanescent, and next to those of 
 common well-known plants : 
 
 1. ^Eruginosus ^Eruginous, bluish-green, like verdigris, and some 
 pine-tree leaves. 
 
 2. Albidus Sand stone colour. 
 
 3. Albus White, chalk-white, cretaceus snow-white, niveus milk- 
 white, lacteus. 
 
 4. A Itrovirens Dark green.* 
 
 5. Ater Deepest black, brown-black, piceus. 
 
 6. Atropurpureus Very dark reddish-purple, as in the Scabiosa 
 atropurpurea. 
 
 7. Atrorubeus Dark-red, as in the Amaranthus hypochondriacus.^ 
 
 8. Aurantiacus Orange colour, as the flowers of the Marigold and 
 Nasturtium. 
 
 9. Aureus Golden yellow, as that of Sunflower and Dandelion. 
 
 10. Azareus Azure blue, like ultramarine ; colour brighter than the 
 Cceruleus; like the pure light-blue flowers of the Cynoglossum omphalodes. 
 
 11. Badius Browner than liver colour. 
 
 12. Brunneus A deep dark-brown. J 
 
 13. Cnsius A dull light-blue grey. 
 
 14. Castaneus Chestnut, russet or orange-brown. 
 
 15. Carneus A flesh colour, as the pale blossom of the Thysperis 
 matronalis. 
 
 16. Cinereus Ash colour. 
 
 17. Cinnabarinus Like red lead or cinnabar; and the gay red of 
 the Oriental Poppy, Papaver Orientalis. 
 
 18. Goccinms High crimson, or bright scarlet ; as the flower of the 
 Salvia Goccinea. 
 
 19. Cceruleus Sky-blue, coelestinus, like the flower of Borage, and the 
 
 * Green viridis, blue-green glaucus, light copper-green malachiticus , 
 copper-green ceruginosus, sea-green thalassinus, black-green atroviridis, olive- 
 green olivaceus, pistachio-green pistacinus, dark-green prusinus, s. obscure 
 viridis, yellow-green luteo viridis. 
 
 fRed ruber, blood-red sanguineus, fire-red igneus, scarlet-red coccineus, 
 crimson-red chermesinus, csirininepuniceus, tile-red lateritius, yellow-red fulvus, 
 light yellow-red testaceus, s. dare fulvus, flesh-red carneus, light flesh-red in- 
 carnatus, s. pallide carneus, rose-red roseus. 
 
 Brown brunneus, red-brown rufus, rust-brown ferrugineus, light rust- 
 brown cinnamomeus s. dare ferrigineus, chestnut-brown castaneus, grey-brown 
 fuscus, umber-brown umbrinus. 
 
556 COLOUKS. 
 
 Veronica Chamadrys ; black-blue, atrocceruleus ; a/ure, azureus ; dark-blue r 
 obscure cyaneus, s. ceruleus ; smoke-blue, fumatus ; grey -blue, cwsius. 
 
 20. Croceus Deep yellow.* 
 
 21. Cyaneus Deep blue, like Prussian blue, and the flower of the 
 Gentiana acaulis. 
 
 22. Fla.vovireus Yellowish-green. 
 
 23. Flavus Yellow, as in the early daffodil. 
 
 24. Flavesceus Yellowish, or pale whitish-yellow. 
 
 25. Ferrugineus Yellowish-brown, as the rust of iron. 
 
 26. Fuscus Greyish- brown. 
 
 27. Glaucus Sea-green, bordering on grey. 
 
 28. Griseus Lively grey ; and when hoary, white grey, Canus ; 
 yellow-grey, lividus ; blue-grey, cinereus ; red-grey, murinus ; brown-grey, 
 luridus ; green-grey, lucanus. 
 
 29. Hepaticas Liver coloured. 
 
 30. Hyalinus Transparent, and like glass. 
 
 31. Lacteus Milk-white. 
 
 32. Liliacinus Lilac, as in the Syringa vulgaris. 
 
 33. Lividus Dark greyish-violet, t 
 
 34. Luteus A deep yellow ; as the outside of the petals of saffron, 
 and the flower of the Cysttis helianthemum.'f. 
 
 35. Miriatus Dull red. 
 
 36. Niger Black. 
 
 37. Ochraceus Yellow, striped with brown ; like yellow ochre, or 
 the feathers on the upper parts of the white owl, Strix flammula. 
 
 38. Olivaceus Olive colour. 
 
 39. Phceniceus Crimson, as the flower of the Pceony. 
 
 40. Puniceus Fine bright red ; Carmine, as in Loberia fulgens. 
 
 41. Purpureus Purple. 
 
 42. Prasinus Grass-green, like the colour of the fresh meadows, 
 before there is any mixture of yellow or other colours. 
 
 43. Ruber Eed. 
 
 44. Rufus Carrot colour, or brownish-red orange. 
 
 45. Rosens Rose colour, or red-pink ; pallide roseus, pale pink. 
 
 46. Sanguineus Blood colour. 
 
 47. Smaragdus Pure green. 
 
 48. Sulphureus Bright but pale yellow, without the slightest orange 
 tinge. 
 
 49. Violaceus Violet, or deep-bluish purple, as in viola odorata. 
 
 50. Vitellinus Yellow, verging to orange, as in pale marigold. See- 
 Byrnes' s Work also. 
 
 * Yellow luteus, sulphur-yellow sulphureus, whitish-yellow alboluteus, 
 straw-yellow stramineus, greyish-yellow flavus, egg-yellow vitelllnus, dark- 
 yellow citrinus; s. obscurt luteus, saffron-yellow croceus, ochre-yellow ochraceus. 
 
 f Violet violaceus, dark purple- violet atropurpureus s. obscure purpureus, 
 purple- violet purpureus, lily- violet liliacinus. 
 
 Lion-orange helvolus, Isabella-orange Isabellinus, minium-orange minia- 
 tut, cinnabar-orange cinnutarinus. 
 
COLOURS. 557 
 
 In the fabrication, as well as the application of 
 Colours, one false step may completely render useless 
 the labour previously devoted to the subject ; and, 
 therefore, in adjusting the proportions of the different 
 components, careful attention is a most desirable 
 accompaniment to skill in the successive peculiar 
 processes. Of the peculiar equilibrium of combina- 
 tive potency, which produces the great variety of 
 tints in the fine essays of the Art, current knowledge 
 is very defective. " Whatever may be the physical 
 cause of colours, the colouring particles which it is 
 the object of the Art of the [Enameller] to apply to 
 [Porcelain, etc.] are known to possess chemical 
 properties, distinguishing them from other sub- 
 stances, dependent on the combinative potencies 
 exercised collectively by their particles, as well as on 
 their reciprocal action, and on their composition, 
 which disposes them, more or less, to assume the 
 solid or the liquid state."- BERTHOLLET. 
 
 On the Incompatibility of Colour* under or 
 upon the same Glaze, as Pink and Mat Blue- 
 Pink, Black, and Brown Rose Colour, Blue, and 
 Black Turquoise, Blue, and Black, Celeste, Pink, 
 and Green, etc., the Manufacturer has been left solely 
 to accident and conjecture as likewise concerning 
 the proportion of innocuous or indifferent com- 
 ponents present in the glaze probably because 
 of defective comprehension of all the conditions 
 of the subject, and incertitude that they are the 
 general result of the difference, on comparing the 
 quantity of alkali with that of earths, or of oxide of 
 lead, used in the glaze. Another peculiarity also 
 must be mentioned, that the high temperature of 
 
558 CHEMISTEY OF POTTERY. 
 
 the potter's oven promotes the chemical potency of 
 the lime on the silica present, which thereby is 
 rendered obedient to the solicitings of acids, and 
 of substances prepared by their agency. 
 
 Whatever may be the maximum of perfection 
 in each process beyond which it seems impossible to 
 advance, certainly, compared with those prior, the 
 last will usually be the smallest ; and as the limit of 
 improvement is rarely approached, except in a few 
 extensive branches of the small number of national 
 Manufactures, the advances will be made, in 
 general, when the former are very numerous, and 
 their utility great and important. 
 
 In reviewing the main subjects which form the 
 present volume, I think every person will be con- 
 vinced that between the Manufacture and the 
 Science of Chemistry there is most important and 
 intimate connection, to which special attention must 
 be paid at every step advanced in the career of 
 improvement. " Science has of necessity, peculiar to 
 itself, a vital energy, a progressive power, superior to 
 the obstacles of time, of things, and of man. Human 
 passions, vulgar ambition, and party interests pass 
 away ; but permanent are the labours of science, the 
 sacrifices made for her sake, the victories borne off 
 in her name ; and which contribute to enlarge that 
 splendid and profitable heritage, on which, at the 
 present day, is based her real grandeur." DUPIN. 
 
 For any one of our Manufacturers to profitably 
 conduct the smallest establishment of this combina- 
 tion of mechanical and chemical industry, and skill 
 of the manufacturing population, he requires to be 
 
COLOUES. 
 
 duly supplied with materials, the united product of 
 several of the counties of England. To produce the 
 commonest painted bowl, used by the poorest 
 peasant wife to contain the breakfast of her rustic 
 husband, the clays of Dorset and Devonshires, the 
 Hints of Kent, the granite of Cornwall, the lead of 
 Montgomery, the manganese of Warwickshire, and 
 the soda of Cheshire, must be conveyed from those 
 respective districts, and by ingenious processes, the 
 results of unnumbered experiments, be made to 
 combine with other substances apparently as hetero- 
 geneous, obtained from other nations. 
 
 The accumulation and dissemination of science 
 and knowledge obey laws altogether distinct and 
 different from those obeyed by physical subjects. 
 Unlike the force, by schoolmen named gramty,. 
 which diminishes rapidly at every successive incre- 
 ment of the distance from the point of contact, its 
 ideal origin, or that of combinative potency, which 
 is inert at determined distances, the further the 
 advancement from the origin of our knowledge the 
 greater the ability is, and more adapted to capacitate 
 its possessors to appropriate fresh supplies. Yet this 
 continual and rapid improvement, instead of inciting 
 fears for the exhaustion of the prolific source, at each 
 advance places them in a more elevated position from 
 which they can readily contemplate the several 
 portions they have passed. 
 
 Every well-wisher of the Manufacture, who can 
 imagine the vast portion of patient thought, of 
 continued labour, of repeated experiment, of happy 
 efforts of genius, and the great amount of expenses 
 incurred, and which have originated and promoted 
 
560 CHEMISTRY OF POTTERY.' 
 
 its progress to the present state, will feel anxious, 
 as much as possible, to prevent the recurrence of the 
 disappointment, vexation, and loss, consequent on 
 deficient chemical information in the persons who 
 have been entrusted with the execution of important 
 improvements, which, though very considerable 
 within the course of a few years, it is extremely 
 desirable to extend much further, by appropriating 
 all the advantages supplied by various and valuable 
 successive discoveries. 
 
 A proud, vain, and heartless sovereign, imagin- 
 ing that his patronage would divert from her general 
 course that important supplier of his exchequer, 
 asked " What can I do to promote TRADE ? " and 
 received for answer the following pertinent remark : 
 " Let Trade take its own course." Deity has kindly 
 enabled man to invent means whereby the pro- 
 ductions of Nature can be worked up into articles of 
 comfort and elegance, with the least possible ex- 
 penditure of manual labour. And when the acquired 
 habits and natural capabilities are carefully regarded 
 in the persons most eminent for practical and 
 theoretical skill, and whose combined efforts are 
 engaged in the general object of improvement, there 
 is presented the greatest probability of success ; and 
 that, ultimately, all the talent of each will regard only 
 this sole object the art of producing a good article at 
 the lowest possible cost. 
 
 Each of the varied and unnumbered mineral 
 products may become the basis of some future 
 extensive Manufacture, to multitudes of the human 
 family a source of employment and wealth. But 
 the superabundant products of the mine, the crude 
 
COLOURS. 561 
 
 treasures exposed constantly to our view, the coal; 
 and iron, and clay the primary sources of all the 
 wealth and power of Britain contain within them 
 other and more valuable principles ; and their 
 development cannot possibly be too free. Their 
 non-existence in other nations of Europe prevents 
 the rivalry in manufacturing greatness ; and ages of 
 research and labour probably will not completely 
 exhaust them and their numerous modifications, 
 perhaps destined to furnish, in perpetual succession, 
 new sources of our wealth and of our happiness. 
 
 The idea has prevailed that the processes of 
 Manufacture are too difficult to be comprehended by 
 the person uninitiated ; but the general principles 
 and mutual relations of the whole can be by most 
 persons of moderate acquirements, although pre- 
 vious knowledge and some skill are needful for the 
 Manufacturer to direct those whom he employs. 
 The same principle for cultivating one kind of 
 industry applies to all others equally, whether the 
 manual or the fine Arts ; the dormant labour, and 
 the inert inventive faculty, need only suitable excite 
 ment to produce comfort and wealth. The advance- 
 ment of a Manufacturer is not always consequent on 
 plans profoundly invested ; sparks may kindle the 
 energies of other minds in a suitable condition to 
 pursue the details, and suggestions acquire im- 
 portance by their objects being thereby presented to 
 the attention of a large manufacturing population. 
 
 Bulwer, in his work entitled England and 
 the English, says : " Wedgwood was remarkably 
 successful, and yet accomplished his purposes inde- 
 pendent of any public School of Design, wherein 
 
 2 o 
 
562 CHEMISTEY OF POTTERY. 
 
 could be pursued the requisite studies for high 
 excellence in the Art of inventing patterns for the 
 Manufacture. Necessity excites, or, which is equally 
 proper, admits the exercise of genius. Thomas[Josiah] 
 Wedgwood could apply only a mere few of the most 
 common principles of the Science of Chemistry to 
 improve the proportions of the components of his 
 wares ; yet he accomplished his object by obtaining 
 the most beautiful and convenient antique specimens, 
 which by his workmen were imitated with scrupulous 
 exactness ; and after having gained celebrity for these 
 copies, he had recourse to Flaxman, the greatest genius 
 of the day, for original designs and advice [and Flax- 
 man employed Mr. John Lucock, who on November 
 5, 1836, showed to myself and a friend his account for 
 work done for Flaxman]. The Manufacturers of 1835 
 produce a far more excellent and valuable fabric ; 
 and yet they are less willing than he was to reward 
 excellence, while they complain of defective talent in 
 persons whom they never excited and solicited, and 
 whose services a moderate remuneration would com- 
 mand." 
 
 The cheapness of our Manufacturers, the staple 
 of our commerce, involves our national' welfare and 
 existence ; and the accumulation of skill and talent 
 to promote this, by increasing the facilities for their 
 production, supplies advantages participated by our- 
 selves and our foreign customers. This cheapness 
 involves likewise a suitable course of induction in the 
 people ; industry and ability unequalled, expertness 
 and skill in manipulation unrivalled ; appropriation 
 of native materials peculiar ; the economy of the 
 Manufactory admirably secured and arranged ; and 
 
COLOURS. 563 
 
 the display of ingenuity in the successive changes 
 of shapes of articles, and of elegance of patterns 
 and decorations, without parallel or limit. This 
 cheapness will command foreign custom, and our 
 markets will have visitors natives of every clime 
 and country prompted by self-interest, and the 
 advantages they will derive from supplies of the 
 products of our industry ; and also, through the 
 same all-powerful motive, vendors of those com- 
 modities for which we proffer a price greater 
 than is obtained in other markets. Such was the 
 real inducement which brought the early dealers; 
 in EARTHENWARES to the first marts, Tyre and 
 Sidon, in Phoenicia, and subsequently to Corinth, 
 and to Etruria. And if in the revolutions of time 
 and events a country should be found whose porcelain 
 and earthenware are vended on cheaper terms than 
 those of the potteries of Britain and other nations of 
 Europe then, even were such spot by supposition 
 located in the most remote or obscure nook of our 
 globe, thither will flock all the earthenware dealers ; 
 and neither fleets, nor armies, nor any other human 
 power, would prevent the present flourishing borough 
 of Stoke-upon-Trent sharing the fate of its once 
 proud predecessors in Phoenicia, in Greece, and in 
 Italy. 
 
 The prevalence of liberal principles in the councils 
 of Britain has tended, remarkably, to excite the 
 talent, genius, enterprise, capital, and industry of the 
 nation ; to accelerate the improvement of Manu- 
 facturers in comparison with those of rival states ; to 
 place them on a vantage ground, only subversive 
 
 by moral disorders resulting from injudicious in- 
 
 2 o2 
 
564 CHEMISTRY OF POTTERY. 
 
 str actions. In calculating the possible injury this 
 Manufacture may sustain from foreign competition 
 as items indispensable must be introduced the 
 facilities of operations, transport, mechanical or 
 automatic aid, etc., must be taken into account. 
 The attempt will doubtless be made by America, 
 whose inhabitants possess equal mechanical genius, 
 plenty of the raw materials, and additional demand, 
 because of the prodigious increase in the amount of 
 population. 
 
 Every crate of pottery, every hogshead of 
 porcelain, on quitting the ports of Britain, bears the 
 seeds of intelligence and fruitful thought to the 
 members of some less enlightened community. 
 Every merchant who visits the locale of our Manu- 
 factures returns home the missionary of freedom, 
 peace and good government. And our steam- 
 engines, which now propel our ships to every port 
 of Europe, and transport our merchandise along our 
 miraculous railroads the talk of all nations are 
 advertisements and vouchers for the value of our 
 enlightened institutions. 
 
 In conclusion, I beg to express the hope, and to 
 avow the sincere desire, that in a comparative short 
 time this Manufacture will be placed as the ne plus 
 ultra among the master-pieces of chemical skill and 
 manual dexterity, creditable alike to our age and 
 country. 
 
THE 
 
 CHEMISTRY OF POTTERY. 
 
 TAS&SS OF THE CHARACTERISTICS OF 
 CHEIVIICAL SVBSTANCEB. 
 
 " The striking mixture of simplicity and complexity which here, as in 
 other parts of Nature, offers itself to our notice, depends on the obedience of 
 the primary elements to the numerical laws which govern the composition 
 of derived forms." WHEWELL. 
 
 ACCURATE knowledge of the CHARACTERISTICS of 
 Substances is most advantageous to the votaries of 
 Chemistry. And yet to verify each seriatim would 
 require more talent, time, and indefatigable industry 
 in him who might attempt the task, however deserv- 
 edly eminent, than could be reasonably expected. 
 Those entitled most to general confidence, because 
 results of the researches of different analysts of 
 acknowledged ability, are scattered through many 
 voluminous and expensive works, and reference to 
 them can be made only at a great expense of time 
 and trouble, even where to the works themselves 
 there is facility of access. 
 
566 CHEMISTRY OF POTTEEY. 
 
 Yet to the chemical student such reference is 
 indispensable, until the particulars become familiar 
 by their frequent reiteration ; unless they can be 
 presented to him in some arrangement that will 
 supply him readily with the entire amount of current 
 knowledge concerning them. Such an auxiliary for 
 this important purpose is a series of CHEMICAL 
 TABLES, and the only drawback on its utility is the 
 possible diminution of the advantage of habitual cal- 
 culation. 
 
 When (in 1831-2) directing the Chemical Class 
 of the Pottery Mechanics' Institution, the desire to 
 present a standard for the researches of accuracy, 
 when these were imitative, and of comparison when 
 original could only be gratified by the constant 
 reference to accredited authorities ; at a sacrifice 
 I was induced to make, solely in hope thereby 
 to confer an advantage on minds just beginning 
 to expand with fervent attachment to science. But 
 the benefits were so obvious that I became more 
 intent on the design of availing myself of the earliest 
 opportunity to collect and tabulate the observed 
 properties and relations of substances. And with- 
 out regard to the labour of the task, I have endea- 
 voured to be, in every particular, most attentive to 
 ensure accuracy. 
 
 Frequently during "these sessions had I been led 
 to notice that certain compounds, whose atomic 
 weights differed, had present the same relative yet 
 not the same absolute number of atoms of the same 
 elements ; that others had precisely the same num- 
 bers of the same elements, yet different or opposite 
 properties, or wholly different kinds of substances. 
 
CHARACTERISTICS OF SUBSTANCES. 567 
 
 These peculiarities surpassed my ability to refer to 
 an adequate cause ; and I was highly gratified to find 
 from subsequent researches, that the respective com- 
 binative potencies which produce such results had 
 engaged the attention of philosophical chemists of 
 the highest celebrity, by them named Polymerism^ 
 Isomerism and Metamerism; and likewise another 
 remarkable peculiarity, noticed especially in natural 
 productions, and named Isomorphism the probable 
 similar form of atoms of certain classes of elements, 
 bases, and acids, whence the substitution of an equiva- 
 lent number of atoms of an element or compound 
 (a like-oxidated or electro-positive component) for 
 those of one usually present ; and yet preserving the 
 external characters, and the figure and the angle 
 of the cleavage planes of the crystal. The substi- 
 tuted components being named vicarious, and vary, 
 as less of one and more of the other, agreeably to their 
 different combinative potencies. 
 
 With regard to natural compounds, although 
 chemists have endeavoured by numerous and most 
 carefully-conducted analyses to discover the nature 
 of the connection between chemical composition 
 and mineral character, yet, as there are not only 
 at present no general and generally-recognised 
 chemical laws, susceptible of application to the 
 various classes of mineral substances, neither many 
 clear determinations of the components of particular 
 species, and so few instances of ability to state the 
 kind of substance, from mentioning very fully the 
 components, that there seemed no likelihood of 
 attaining to accuracy in giving insertion to the 
 published formulae. 
 
568 CHEMISTRY OF POTTEKY. 
 
 The Series of Tables may not inaptly be com- 
 pared to a vast granary of a widely-extended domain, 
 containing the different portions of the harvest of 
 Chemical Science already ripe, collected by the 
 perseverance of the laborant and the gleaner, and 
 where to each kind is most carefully assigned its 
 proper situation with regard to all the others, whence 
 it can be either removed or omitted only through 
 inattention or ignorance. The arrangement regards 
 the regular systematic succession from the component 
 most receptive to that most communicative, and pre- 
 senting the proper place for any which may hereafter 
 be recognised and determined. It may be stated, 
 that the irregular and outspread surface of the 
 domain itself presents numerous chief divisions, in 
 each of which may be noticed spots, which defy alike 
 the estimate and direction of the surveyor, and the 
 management of the improver ; in others are indica- 
 tions of the bassetings of rich ore, which needs to be 
 determined by the observations and experiments of 
 persons who especially cultivate the sciences of calcu- 
 lation ; here we find veins scarcely opened, but 
 which will require from those who can devote all their 
 industry and attention, the application of all their 
 ingenuity to determine the precise limits of the veins ; 
 their assiduity to avoid whatever obstacles might 
 retard their progress or cause failure in the design ; 
 and their most improved methods to pursue those 
 appearances of the lode which promise the supply of 
 the hoped-for object ; and there are not wanting 
 others veins where the absence of a common prin- 
 ciple in the working, or the indiscriminate choice of 
 means to treat and determine the products, or de- 
 
CHAKACTERISTICS 0F SUBSTANCES. 569 
 
 fective instructions for the acquisition of the object, 
 will be found to have hitherto precluded success. 
 
 For the chemical student to economise time, 
 labour, and thought, to indicate the components and 
 quantities of the elements in substances, indispen- 
 sable are CHEMICAL FORMULAE, and a clear and brief 
 NOTATION, although to some the requisite numerous 
 symbols may be repulsive. The facility and con- 
 venience of a Collection of Symbols representing 
 the known Combinations of Forms, however multi- 
 farious, can be duly estimated only by persons 
 familiar therewith. In regard to natural substances, 
 notation is indispensable, because frequently their 
 composition is much too complex to be clearly and 
 distinctly expressed by the resources of the language 
 of Modern Chemistry. In the latest improvements 
 of the science there will be merely needful a change 
 of the Initial where a vicarious element is found ; 
 and by employing the sign of the element for the 
 prime or single atom, and affixing an exponent of the 
 multiples, the elements and their ratios in the com- 
 position of a substance will be clearly restricted 
 and indicated. This method of employing symbols 
 for the components and equivalents of the elements of 
 a compound, when so frequently employed as to be 
 properly comprehended, will be as useful in the facile 
 indication of chemical combinative potency, as are 
 the Arabic digits in the science of arithmetic.* The 
 
 *Dr. Turner states, that, in some instances, the equivalents 
 are so nearly simple multiples of that of hydrogen that they 
 may be taken as such without appreciable error ; but in many 
 cases, the numbers given by experiment cannot be reconciled 
 
570 CHEMISTRY* OF POTTERY. 
 
 standard adopted is hydrogen, and its communica- 
 tive or receptive potency with each other element is 
 indicated by the number affixed to each element in 
 the column next to that wherein is the symbol ; thus 
 4 of oxygen combine with '25 of hydrogen ; therefore 
 hydrogen being *25, 4 is the combinative potency of 
 oxygen. This latter is also a standard for those 
 substances which do not appropriate hydrogen, their 
 equivalent being determined by the quantity which 
 combines with the equivalent quantity of another 
 substance that does combine with hydrogen ; silver, 
 for instance, is indifferent to hydrogen ; yet as 27*5 
 of silver combine with 4 of oxygen, and 4 of this 
 combine with *25 of hydrogen, then 27*5 is the equi- 
 valent number of the combinative potency of silver. 
 And so of all other substances.* 
 
 with hypothesis. The following are the numbers which he is 
 disposed to believe very nearly correct : lead 103'6, silver 108, 
 chlorine 35-42, barium 68-7, mercury 202, perhaps slightly 
 higher, but not higher than 2023, nitrogen 14 '2, but not lower 
 than 14, and sulphur nearer to 16'1 than 16. Third Report of 
 British Association for the Advancement of Science, p. 399. 
 
 * The combining quantities of the elements are determinate 
 weights, and the combining quantities of the gases are deter- 
 minate measures. Thus a cubic inch of one gas combines with a 
 cubic inch of another gas, and not with a fractional part of a 
 cubic inch. And it is requisite further to state, that that deter- 
 minate weight of a solid body which combines with a cubic inch 
 of one gas combines also with a cubic inch, or with 2 or 3 or 
 some entire number of cubic inches of another gas, and not with 
 a fractional measure. 
 
 There is, consequently, a certain weight of each solid element 
 which is equivalent in combination to a gaseous volume. 
 
 If every element could be obtained in the state of gas, the 
 
CHARACTERISTICS OF SUBSTANCES. 571 
 
 problem of determining the atomic weights could be at once 
 solved by weighing an equal bulk of each of the gases, since, in 
 reality, the atomic weights would be neither more nor less than 
 the specific gravities of the gases. But unfortunately this method 
 of determining the atomic weights is limited to the few following 
 elements : 
 
 Oxygen. 4 
 
 Chlorine 9 
 
 Hydrogen 0'25 
 
 Nitrogen 3'5 
 
 to which may possibly be added 
 
 Iodine 32 
 
 Mercury 25 
 
 Limited, however, as this method of determining the atomic 
 weights is, it is of the greatest importance, being the only direct 
 way of strictly comparing the elementary atoms which has yet 
 been discovered. From the weights of equal volumes of the 
 gaseous elements, we can form a distinct idea of the comparative 
 weights of their atoms ; but every other method of determining 
 atomic weights affords at best what we must denominate PRESUMP- 
 TIVE evidence, and this, if pretty clear with respect to a number 
 of elements, is often, in regard to others, of the most dubious 
 description. The consequence is, that what are called the atomic 
 weights of a good many elements are merely approximations or 
 guesses. 
 
572 
 
 m 
 W 
 O 
 ^ 
 W 
 P^ 
 
 w 
 fe 
 
 I 
 
 tl 
 <J 
 p^ 
 
 o 
 
 Op 
 
 -' g 
 
 Trivial Name. 
 
 5 
 
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 5 Q > Q a 
 
 5 w o a o 
 
 g jai'BAY 
 
 'i 
 
 
 J -asug 
 
 -(- -r--r- H- 
 
 TPV 
 
 TH O CO CO 
 rH T-H 
 
 -"aSS 
 
 IO 01 
 
 Stnsnji 
 
 
 
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 auinjOA 
 .#ui!)insa'}i 
 
 13 ~* tJ rrj 
 CO CO ,-M 
 
 saraniOA { 
 
 ISIS 
 
 rBuop.iodo.itj 
 
 
 
 ^ ob 
 
 'o09 'jaqx 
 
 08 'taoa^g 
 
 CO CO CO 
 
 .-S 'I = J|V 
 
 rH rH OJ 
 rH rH CM O C- 
 rH rH Ol TH TH 
 rH rH Ol C30 CO 
 rH TH CN rH r-H 
 
 rH Ol 
 rH Ol 
 
 CO t- 
 
 CO TH 
 
 i 
 
 o, J&VBAY 
 
 02 
 
 rH T-H rH 
 
 'saaqtun^ 
 ^uajiBAinbg 35) 
 ^qStaAv cno^v 
 
 Ol CM Ol O t- Ol 
 
 TH TH 00 00 01 6 CO 01 CO 01 O CO O 00 CO 
 iHOlrHCOrHOl THCOO1 TH 
 
 -uen^ aiaq^ 
 ptre 's^uau 
 -odraoo aq^ 
 
 = 
 
 anopo 
 
 | ^^^|^^IUs^ 
 
 UlJOjf 
 
 ^^^^^^S 
 
 333 ^^S^ 
 
 Name of the Element, 
 and its Combinations. 
 
 rH Ol CO TH O 
 
 S5 D 
 
 
 
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 X! p'S 
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 rH Ol rH Ol 
 
 
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 c co O P Q' 
 
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 il 
 
 573 
 
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 w 
 
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 CO *^ CO 
 
 t- CO 
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 G5 *O O 
 
 TH 
 
 CO 
 
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 TH 
 
 TH rH 
 
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 10 
 
 CO 
 
 * 
 
 rH CO O HH TH 
 >O O O TH CO 
 
 TH CO O 1O TH CO 
 
 t- t- CM 
 
 CN CN 1C 
 
 O 
 
 CO 
 
 |S 
 
 t- 
 
 TH rH TH CN CN CN 
 
 TH TH rH 
 
 CO 
 
 
 |H 
 
 IO O X 
 
 CNipiplOlOrH 
 
 cb t-rHibcbccooidicb 
 
 TH iH CN CO Oi 
 
 CNTHCNCNCNIOTH 
 
 O 
 CN 
 
 iO 
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 00 
 
 2 2 S 2 S 
 
 THCNrHCNCOrH THCN rH CN TH CN CO TH rH CN 
 
 iH CN CO 
 
 
 
 
 
 % 
 
 
 
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 g 
 
 
 
 
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 Oxide . 
 
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 j |,a 
 
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 -<! O K 
 
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 'c 
 
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 s^uauoduioo 
 
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 'satpui oiqno 
 
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 ouaqd 
 
 I = 
 
 XO 
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 t- 
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 CM CM <M 
 
 -u-enfr item 
 pu^ 'e^uau 
 
 raaoj 
 
 ment 
 ions. 
 
 SjD 
 
 2 E Js 
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 M M 
 
575 
 
 t- + 
 
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 bb 
 t- to 
 
 s o 
 
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 TH TH 
 
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 ooo 
 
 CO O O5 
 
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 c* 6 1- <b 
 
 TH CO TH O 
 
 gg 
 
 <M <M 
 
 TH TH 
 
 05 CO 
 CO CN 
 
 CM o CM oq 
 
 ?? ? ? 
 
 CO CO 
 
 O O O t- OQ 
 
 TH (M CM 
 
 THr-l CO 
 
 ^B|"8|"8lliiils|||llg 
 
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 1*1 I I 
 
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 SO) 
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 CM CO TH O1 
 
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 ^ r3 s t 
 
 fc-e 
 
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576 
 
 as^g 
 
 ppy 
 
 junjuiadtuaj, 
 
 rjt 
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 saumjOA ui 
 s^uauodraoo 
 
 s^uauodoioo 
 
 *o09 
 
 'saqouj oiqno 
 OOlJO?q*PA4 | 
 
 I=aiy 
 ouaqd 
 
 S 55 
 
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 imi 
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 p 01 01 
 
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 Ol Ol Ol 
 
 
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 nuoj 
 
 me of the E 
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577 
 
 X 
 
 rH 1O 
 
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 b- CN 
 
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 cb D t- t- 
 
 000 
 
 O ~-tr> 
 
 XO O CO 
 
 O Oi 
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 OO O5 00 T-H 
 
 o o ob ob 
 
 O O T* 10 
 
 -* 00 r-H 00 
 
 CN di o o 
 
 CO 00 tr* 
 
 t- "* CO 
 
 0500 
 <M rjl 
 CO CN 
 
 feS 
 
 4 
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578 
 
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 t- CO t- *O 
 
 cb ob 
 
 Ttl CO 
 
 CO T ( O O 'H D^ 00 
 
 iot- TH 
 
 r-l CO T 1 Tl 
 
 'PPV 
 
 co co co 
 
 rH Ttf <N t- CO O O COt-COilTt<COOOO CO 
 
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 THTHcbcocbTH<o4t<^tttbcb<>icboi>-cb OCOCJ^HO O 
 
 C^- CO CO *O CO CO CO t^* t t^* CO *O t" t- t^ CO t^* 00 
 
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 GOT jo ^qgiOAY 
 
 ouaqd 
 
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 HO5'Ho"*Gqt>CO 
 <NOOt-t-iO-*THCO 
 
 -odraoo sqi 
 
 uwo.1 
 
 S 
 
 Name of the Element, 
 and its Combinations. 
 
 
 s 
 
 '' 
 
 
 
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 oS-S iSS J^H o S S 30-5 a SiftS So iS S w'm S W Q o 3 Q 
 
579 
 
 'so * 1C 
 
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 00 CO C~ -* 
 
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 co co Ci 
 
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 00 
 
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 i^ 1,5^^11^ 
 
580 
 
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 GOT j 
 
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 -oduioo aq; 
 
 oooooooooooooooooooooooo 
 
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 the Eleme 
 ombinatio 
 
 Na 
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581 
 
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 fl d 
 
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 t- TH 10 
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 CO 
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 CN CO 
 t~ O CO 
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 CNCNIC<l 
 
 
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 rH CM CO 
 
 s s -s-s 
 
 S P H J 
 
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OBSERVATIONS. 
 
 OXYGEN is without colour, or odour, or action on tincture of 
 litmus, or on lime-water ; it is partially soluble in w 7 ater, and in- 
 creases the energies of animals, and the force of combustion. It is 
 present with most substances, but its aciduline potency involves 
 the presence also of hydrogen. 
 
 SULPHUR. Sulphurous Acid has a remarkable pungent 
 odour, destroys fermentation and vegetable tints, liquefies under 
 the pressure of two atmospheres at 45 R, and in 33 volumes 
 combines with water. Its presence with bases is indicated by 
 a white precipitate of tests 20, 30, 35, not soluble in water, but 
 in acids. With the alkalies and earths it forms salts named 
 Sulphites, those of the former being soluble, of the latter insoluble 
 in water ; these salts appropriate oxygen from nitric and nitrous 
 acids, also sluggishly from the air, forming sulphates by their 
 decomposition, but the sulphurous acid evolves in effervescence, 
 when is present either sulphuric, muriatic, phosphoric, or arsenic 
 acid. Ignition with charcoal forms the greater number into 
 sulphurets, and the action of heat alters them into a sulphate, or 
 an oxide, or a metal. When perfectly dry they resist the action 
 of chlorine ; but when moisture is present, the gas of the acid 
 evolves, and leaves a sulphate and a muriate. Hyposulphurous 
 Acids forms the salts named Hyposulphites, all of which are 
 decomposed by either sulphuric, muriatic, fluoric, phosphoric, or 
 arsenic acid, the sulphurous acid gas evolves, the sulphur preci- 
 pitates, and a fresh salt results. Its presence is indicated by a 
 ivhite precipitate when test 30, 32, or 35 is exhibited. The 
 hyposulphates of the alkalies are very soluble, others less so, in 
 water ; the solution dissolves recently-prepared chloride of silver, 
 and acquires intense sweetness, without metallic savour. Oil of 
 Vitriol of the strongest kind freezes at 15 F., and of 1*78 at 32, 
 and solidifies at 45. The fuming acid of Nordausen is 1-9. 
 On exhibiting test 20, 30, 35, a white insoluble precipitate results, 
 also from nitrate of barytes and nitrate of lead (extremely 
 
OBSEKVATIONS. 585 
 
 corrosive). The salts formed are named Sulphates, which decom- 
 pose at a high temperature with boracic or phosphoric acid 
 present ; those of the alkalies and alkaline earths are indifferent 
 to heat, unless mixed with charcoal, when they change into 
 sulphurets.; the others are by heat decomposed (except that of 
 lead, which also is soluble in plus of nitric acid, muriatic acid, 
 and caustic potash) ; those of barytes, lead, tin, bismuth, mercury, 
 and antimony, are wholly, and those of strontian, lime, yttria, 
 cerium, and silver, are partially indifferent to the action of water, 
 which efficiently solicits the others to combination. Hypo sulphuric 
 Acid is without odour ; and with barytes, strontian, and the oxides 
 of some metals, forms the salts named Hyposiilphates, soluble 
 in water, but some wholly, others sluggishly, indifferent to the 
 action of the atmosphere, or becoming sulphates ; yet boiling 
 changes them into sulphates and sulphites. Ignition causes 
 sulphurous gas to evolve, and transforms them into sulphates. On 
 exhibiting to any of these salts concentrated sulphuric acid, or hot 
 diluted, much sulphurous gas evolves, decomposing the hyposul- 
 phuric acid, which latter evolves unaltered when the diluted acid 
 is cold. Hydrosulphwic Acid. The sulphurets of the alkalies and 
 alkaline earths dissolve in water, and in air the hydrosulphurets 
 decompose; and of these the solutions are decomposed by the 
 acids appropriating the base, while sulphuretted hydrogen evolves, 
 yet the sulphur remains present, only precipitating when plus 
 of nitric or nitrous acid is exhibited. The readiest solvent of 
 sulphurets is dilute muriatic acid. The salts of the alkalies and 
 alkaline earths are indifferent to the soluble hydrosulphurets, 
 which behave to the others in exhibiting white or coloured 
 precipitates. The Chlorides are red by reflected light, but by 
 transmitted yellowish-green. 
 
 NITKOGEN is without colour or savour, and is not easily 
 discriminated ; it destroys combustion and vitality, and does not 
 precipitate the lime present in lime-water. The Protoxide has a 
 weak pleasant odour and sweet savour ; it greatly excites vitality 
 and combustion ; is appropriated by equal volume of water, and 
 is liquid under pressure of 50 atmospheres at 45 F. The 
 Deutoxide, or nitrous gas, is without colour until atmospheric air 
 or oxygen is present, when brilliant red acid vapour (or nitrous 
 acid gas) appears ; it destroys vitality and combustion, does not 
 alter litmus tincture, and about 6 or 8 per cent, is appropriated 
 
586 OBSERVATIONS. 
 
 t>y water. Nitrous acid gas is red, and forms the salts named 
 Nitrites, having one dose (a third) of oxygen less than Nitrates. 
 It is very volatile, extremely corrosive, and when in small 
 quantities added to water, there result deutoxide and nitric acid. 
 All the Hyponitrites already formed are soluble in water, 
 detonate when mixed with charcoal and ignited, by heat decom- 
 pose, and the acid evolves into oxygen and nitrous acid or 
 nitrogen ; and some of them when slightly heated in air appro- 
 priate its oxygen and become nitrates. When sulphuric, nitric, 
 muriatic, phosphoric, fluoric, arsenic, or some other strong acid 
 is exhibited, red vapour evolves, and their acid is converted into 
 nitric acid and nitric oxide. Theory now proves that Aquafortis 
 is a true nitrate, having a dose of hydrogen in place of one of 
 .a metal. Nitric Acid is very corrosive, and, like nitrous acid, 
 powerfully oxidates substances ; boiling will increase this potency 
 till the specific gravity of the acid is 1-42, when continued boiling 
 diminishes it ; it freezes at 50 F. The salts named Nitrates, 
 when mixed with combustibles, charcoal, sulphur, phosphorus, 
 etc., detonate on being ignited; they are soluble in water readily 
 or partially as there is plus or minus of acid present ; they all 
 decompose by high temperature, and by interchange of acid, 
 when there is exhibited sulphuric, phosphoric, fluoric, or arsenic 
 acid ; and muriatic acid resolves with it into chlorine and nitrous 
 acid, forming the Aqua Regia employed to dissolve gold and 
 certain other metals. The Chloride is like oil; it distils at 160, 
 explodes at - 212, and with combustibles is very explosive. The 
 Iodide must be carefully treated, for slight pressure will cause the 
 moist, as drying will the loose, mass to violently detonate. 
 
 CHLOBINE is a yellowish-green gas, which under pressure of 
 more than 4 atmospheres, at 60 F., liquefies into a dark yellow 
 oily substance ; its odour is suffocating, yet the gas supports 
 combustion; with little water present fine yellow crystals form, 
 but with much the liquid is permanent ; it bleaches all vegetable 
 fabrics readily, but sluggishly affects animal productions in cloth. 
 The Protoxide and Peroxide are deep green in colour, and 
 explode violently, the former with the warmth of the hand, the 
 latter at 212 F. ; the former rapidly, the other about 8 volumes, 
 mixes with water ; and both powerfully bleach vegetable fabrics. 
 Chloric Acid is decomposed, and its oxygen appropriated, by 
 several strong acids, muriatic, sulphurous, phosphorous, etc. The 
 
OBSERVATIONS. 587 
 
 salts named Chlorates are all (except that of mercury) soluble in 
 water, and many of them likewise in alcohol ; yet no base will 
 form a precipitate in these solutions. On being ignited, dry 
 chlorates by their oxygen evolving are converted into chlorides, 
 which dissolve in water, and copiously precipitate when test 32 is 
 exhibited. On being carefully warmed with a little dilute muriatic 
 acid, the greenish-yellow protoxide of chlorine evolves ; when a 
 very minute portion of a chlorate is treated with concentrated 
 sulphuric acid, the peroxide of chlorine evolves ; but plus of the 
 salt involves liability to explosion ; and flame will evolve when 5 
 parts of a chlorate are treated with 1 of the fuming sulphuric 
 acid. The chlorate of potash, mixed with any combustible, is 
 extremely explosive, by heat resolving into oxygen and chloride of 
 potassium, and decomposable by sulphurous, sulphuric, or muriatic 
 acid. Perchloric Acid readily detects the presence of potash, 
 because the compound requires 65 parts of water, and is insoluble 
 in alcohol. Muriatic Acid is a real chloride, having a dose of 
 hydrogen instead of one of a metal. Under the pressure of four 
 atmospheres, at the temperature of 50 F., it is liquid ; freezes at 
 60 ; test 32 precipitates white, curd, soluble in ammonia but not 
 in nitric acid. Except the chloride of silver, all chlorides are 
 soluble in water, forming the compounds. named Miiriates ; most 
 of these with plus of base are insoluble in water, those of the 
 earths and alkalies are indifferent to the action of hydrogen, which 
 efficiently solicits the others ; potash, also soda, decomposes all 
 muriates of other bases ; and the water present in the pores of 
 charcoal aids its potency over them. Many of the chlorides are 
 by heat volatilised ; but only those of some of the noble metals 
 (gold, platinum, etc.) are decomposed ; this results also when to 
 many of them sulphuric acid is exhibited, as chlorine evolves 
 when they are treated with nitric acid. The Carburet is 
 volatile, and is called Chloric Ether. Chloral is oily and trans- 
 parent, but with water, agitation forms a white solid hydrate. 
 BROMINE is a very volatile orange-red vapour, which pecu- 
 liarly affects the temples and eyes (as chlorine does the throat, 
 and iodine the nose) ; but the chloric, bromic, or iodic acid is not 
 supplied by Nature ; with little water it crystallises of a beautiful 
 hyacinth red, but with much water the liquid is permanent. It 
 bleaches vegetable tints, displaces iodine, is displaced by chlorine, 
 appropriated by water, alcohol and ether, and forms the salts 
 
58S OBSERVATIONS. 
 
 named Bromides, many of which, in nitric acid, lose a portion of 
 their element, and a solvent of gold is formed. Bromic Acid, 
 with characters much like chloric acid, is decomposed by 
 sulphurous acid ; as its salts, named Bromates, are by concen- 
 trated sulphuric acid, while bromine gas and oxygen evolve. 
 This latter effect also ensues on ignition, when Bromides result. 
 The bromates are all sluggish or indifferent to the action of water ; 
 and, like chlorates, the mixture with a combustible is explosive. 
 Hydrobromic Acid is colourless, but has a pungent odour, and 
 is quickly appropriated by water. When the bromides, soluble 
 in water, have their resulting hydrobromates treated with sul- 
 phuric acid, the exhibition of chlorine causes to evolve the 
 bromine, which renders sulphuric ether golden yellow, in which 
 starch causes an orange precipitate. The Carburet is volatile, 
 has an aromatic odour, sweet savour, sinks in water, and solidifies 
 at 21 to 23 F. 
 
 IODINE is black, crystalline, with a weak odour (already 
 noticed), sharp acrid savour, slight bleaching power on vegetables, 
 volatilises in a beautiful violet vapour, discolours the skin ; soluble 
 in alcohol, indifferent to the action of water (except 1-7000 part), 
 with a cold solution of starch an intense blue tint ensues, which 
 hot water destroys ; chlorine and bromine separate it from its 
 compounds. lodic Acid by fusion is decomposed, also by 
 sulphuric acid ; it is indifferent to alcohol, but soluble in water, 
 and with many of the vegetable alkalies forms compounds 
 indifferent to water. Some of the Iodides, and most of the 
 Iodates, are sluggish, others indifferent to water, even those of 
 metals which decompose it. Hot muriatic acid and sulphurous 
 acid, very readily, but sulphuric acid sluggishly, decomposes the 
 iodates ; as does a dull red heat, when oxygen only, or this with 
 iodine, evolving, an iodide results. Like chlorates and bromates, 
 when mixed with combustibles, iodates detonate, but less violently, 
 on being heated. Hydriodic Acid has a pungent odour, and is 
 appropriated by water, and the Chloriodic Acid, with orange tint, 
 forming two compounds, a chloride soluble in ether, alcohol and 
 water ; and perchloride resolvable into muriatic and iodic acids. 
 The Carburet sinks in sulphuric acid, and has an aromatic odour 
 and sweet savour. The Hydriodates acquire an orange tint by 
 appropriating iodine. Chlorine appropriates the hydrogen of 
 these, which are decomposed also by sulphuric or nitric acid, and 
 
OBSERVATIONS. 589 
 
 the liberated iodine is detected by the blue tinge given to a 
 solution of starch. Hydriodates, in solution, supply to test 20 a 
 precipitate, russet coloured, concentrated, primrose, when diluted ; 
 and scarlet to chloride of mercury. 
 
 FLUORINE is not isolated, but when liberated from one element 
 combines with another. The Hydrofluoric Acid is a real fluoride 
 having a dose of hydrogen instead of one of a metal. At 32 it 
 is fluid, yet extremely volatile, rapidly appropriated by water, 
 powerfully acts on silicates and animal fibre. The Fluorides of 
 potash, soda, ammonia, and silver are soluble in water, the other 
 in plus of acid. Those of the alkalies with excess of acid form, 
 with some metallic oxides, salts sluggishly soluble. Dry fluorides 
 are indifferent to the action of heat ; but moistened, some of them 
 are decomposed, because from the water the hydrogen evolves, 
 changing the fluorine into hydrofluoric acid, which evolves as white 
 acrid vapour that corrodes glass. Hydrated sulphuric, phosphoric, 
 and arsenic acid, will decompose the fluorides, the water also 
 decomposing, and its hydrogen acting as just stated, while the 
 resulting hydrofluoric acid evolves as already mentioned. 
 Fluosilicic Acid most potently solicits water to 3*65 its volume, and 
 much silica is deposited. 
 
 PHOSPHORUS is extremely inflammable, and so rapidly appro- 
 priates the oxygen of the atmosphere, as to enter into combustion 
 on a slight rise of temperature ; the ordinary rise of this, on a 
 summer's day, has been known to cause this with phosphorus 
 laid on coarse blotting-paper. Hypophosphorus and Phosphorus 
 Acids have intense deoxidating potency, and the latter appro- 
 priates the oxygen of the atmosphere. The Phosphites are, many 
 wholly, others partially, indifferent to water ; but by the presence 
 of chlorine, concentrated nitric acid, the peroxide of mercury, 
 and the oxides of several other metals, become phosphates. At 
 the temperature 60 F. they are indifferent to oxygen ; but when 
 excluded from the air, and the temperature is raised, phospho- 
 retted hydrogen evolves, a little phosphorus is eliminated, and a 
 subphosphate remains. Phosphoric Acid is very deliquescent ; 
 the Protochloride, as also the Per chloride, is separated into 
 muriatic and phosphoric acids when water is present ; at a low 
 temperature the Iodide is formed, which, when water is present, 
 resolves into hydriodic and phosphoric acids. The Phosphates 
 of the alkalies and acids are soluble in water, and those of the 
 
590 OBSEEVATIONS. 
 
 earths, etc., are so in nitric acid ; they are sluggish towards 
 sulphuric acid, but caustic and carbonated alkalies precipitate 
 them slightly altered in aciduline solutions, and a yellow preci- 
 pitate obeys the cautious exhibition of test 32 ; they are, alone, 
 indifferent to the action of heat ; but mixed with charcoal, 
 either phosphorus evolves, or they become phosphorets. 
 
 BORON is a dark-olive powder, without odour or savour 
 which, when heated in a close vessel, shrivels without volati- 
 lising ; but in air, inflames and forms dry Boracic Acid, soluble 
 in alcohol, and tinging flame green. The salts are named Boratcs, 
 and all are almost indifferent to water, those of the alkalies being 
 least so; at a high temperature most of them melt, and then 
 solicit and become tinged by most metallic oxides ; those of the 
 alkalies and earths, never, but those of the other bases partially, 
 are decomposed when ignited with charcoal, sulphur, etc. ; also 
 by sulphuric acid, etc. Trie Chloride, when water is present, which 
 it powerfully solicits, resolves into muriatic and oracic acids. 
 Fluoboric Acid solicits water to '700 times its volume, and acts 
 powerfully on animal matter. 
 
 CARBON (except as diamond) is dull, black, opaque, and 
 inflammable ; it powerfully solicits oxygen in forming Carbonic 
 Acid, also hydrogen, forming the gas now used to illuminate our 
 towns ; it is insoluble in water, infusible by heat, and incapable 
 of being volatilised ; as charcoal, it destroys fetid odours ; and 
 also many tints of colour fade when boiled in water with char- 
 coal present, and with many bases it forms Carburets. Carbonic 
 Oxide burns with a blue flame, and when equal volumes of it and 
 protoxide of nitrogen have the electric spark passed through 
 them, the additional oxygen obtained forms equal volumes of 
 Carbonic Acid and nitrogen. This acid liquefies under the 
 pressure of two atmospheres at 45 F. evolves during fermentation, 
 and is absorbed by water, which lime renders milky ; it destroys 
 vitality and combustion, and with a few bases forms the salts 
 named Carbonates, of which only those of the alkalies solicit 
 water to combination, though many by excess of acid become 
 Bicarbonates, which excess again evolves during boiling ; and 
 when mixed with charcoal, sulphur, silica, etc., they are decom- 
 posed by heat, to which latter the carbonates of potash, soda, 
 lithia, and barytes are indifferent ; that of ammonia is volatile; 
 the acid evolves during effervescence when acids are present. 
 
OBSERVATIONS. 591 
 
 The Hydrite powerfully solicits water, and when one volume 
 of gas and four volumes of chlorine over water are exposed to 
 light, carbonic and muriatic acids result. The destructive fires 
 of coal-mines originate in the ignition of this gas in the proportion 
 of one or more volumes to fourteen of air. The Chlorocarbonic 
 Acid, called also Phosgene gas, combines with four volumes of 
 ammoniacal gas ; and when water is present, it resolves into 
 carbonic and muriatic acids. The Sulphite is colourless, extremely 
 refractive, inflammable, volatile and offensive. The Bichloride, 
 soft and fibrous, fuses easily, is soluble in alcohol, and crystallises, 
 and likewise the Perchloride, which has an aromatic odour, and 
 may be distilled ; and much similar in odour and savour is the 
 per-iodide. Naphthaline has an aromatic odour, and combines 
 with sulphuric acid ; and the Sulpho-naphthalic acid is readily 
 dissolved by alcohol and water, and with bases forms salts. 
 Cyanogen burns with a crimson flame, liquefies by the pressure 
 of - 4 atmospheres, at 45 F. water appropriates 45, and alcohol 
 23 volumes. The Sulphur et compound (C 2 ZH S 2 ) 3 and 
 water 1, form red crystals. The Bromide is colourless, volatile, 
 and by caustic potash forms hydro-cyanate and hydro-bromate of 
 potash. The Iodide is volatile, caustic, sinks in sulphuric acid, 
 and is indifferent to a temperature of 212 F. Cyanic Acid with 
 ammonia forms Urea, with water present resolves into ammonia 
 and carbonic acid ; and with a solution, oxide of lead, or of silver, 
 forms an insoluble precipitate. Hydrocyanic Acid is a very 
 powerful poison, and at 0*999 spec. grav. is employed for medical 
 purposes, which chlorine decomposes ; the acid is volatile, and 
 the odour is rather fragrant like peach blossoms ; at zero it freezes. 
 The Sulphocyanic Acid with protoxide of copper forms a white 
 salt, but a blood-red one with peroxide of iron. The Chlorocyanic 
 Acid is a gas at 60 F., fluid between 5 and 10'5, and solid at 
 zero. The Ferrocyanic Acid with potash and iron forms the 
 valuable compounds Prussian blue and prussiate of potash. 
 Cyanuric Acid, in transparent crystals, remains indifferent to 
 boiling sulphuric or nitric acid. Oxalic Acid crystallises with 
 three proportions of water, two of which escape as steam by 
 boiling ; boiling- water appropriates a quantity at present (1836) 
 not determined, it appropriates the most minute portions of lime 
 present in a neutral solution ; by heat the Oxalates decompose 
 into a metal, oxide, or carbonate ; and pouring sulphuric acid on 
 
592 OBSERVATIONS. 
 
 binoxalate of potash causes carbonic acid gas and carbonic oxide 
 to evolve, and when these are passed through lime-water, the 
 former is appropriated, and the latter can be collected. The 
 Formic Acid of the stated specific gravity has pungent odour 
 like acetic acid, forms barytes, lime, magnesia, etc., in crystal salts ; 
 by sulphuric acid is resolved into water and carbonic oxide, or 
 carbonic acid and water by heating with peroxide of mercury. 
 Acetic Acid of A 1. x W 1. is volatile, pungent, refreshing, 
 appropriates essential oils and resins ; forms the salts named 
 ascetates, which by sulphuric acid are decomposed, the acetic 
 acid evolving. The Pyro-acetic spirit is inflammable, volatile, 
 with a peculiar odour, and miscible with alcohol, ether, or water. 
 Tartaric Acid forms the salts named Tartrates, and many of 
 these are insoluble in water, yet soluble in excess of the acid ; 
 with salts of potash the precipitate is bitartrate of potash ; and 
 when the acid is in excess, it precipitates by muriate of platinum 
 from a solution neutralised by carbonate of soda, and boils black. 
 The Lactic Acid salts are soluble in alcohol, but do not crystallise. 
 Most of the Citrates are soluble in water, and lime-water deter- 
 mines the presence of the acid. The Malate of lime, as that of 
 lead, is appropriated by hot water. Benzoic Acid is readily by 
 alcohol, but by water partially appropriated, and is separated 
 from Benzoates by" the strong acids ; these salts (as the Succinates) 
 precipitate red-brown the persalts of iron ; in carefully neutralised 
 solutions they do not precipitate salts of manganese. Gallic Acid 
 precipitates black persalts of iron, is indifferent to gelatine, and 
 by heat pyrogallic acid sublimes. Camphor is volatile, the 
 odour aromatic, and is indifferent to water, but appropriated by 
 alcohol ; and very similar in these latter properties are the Mar- 
 gar ic Acid and the Oleic. By saponifying vegetable oil with 
 potash, and treating the soap with alcohol, at '821, these two 
 acids and stearine are obtained ; the oleate of potash is appro- 
 priated, and the margarate remains insoluble, and both are 
 decomposed by the strong acids. The margaric has 3-4, the 
 oleic 3 '8 per cent, water present. Glycerine is a non-fermentative 
 syrupy, very sweet fluid, appropriated by water or alcohol. 
 Cholesterine, the basis of urinary calculi, does not saponify with 
 alkalies, is indifferent to water, but appropriated by alcohol. 
 Urea is readily appropriated by alcohol and water ; its com- 
 pounds with oxalic and nitric acids are sluggishly appropriated 
 
OBSEKVATIONS. 593 
 
 by water ; when an alkali or alkaline earth is exhibited, de- 
 composition ensues, and carbonate of ammonia results. Uric 
 Acid is without savour, indifferent to water or alcohol, appro- 
 priated by alkalies, which acids precipitate again ; also appropriated 
 by diluted nitric acid, and a crimson stain follows careful evapo- 
 ration. Sugar, CHO (7*25), is white, sweet, brittle, inodourous, 
 appropriated by water or alcohol ; and when treated with nitric 
 acid, the hydrogen is separated and oxalic acid is formed. Gum 
 is indifferent to alcohol ; and ether, yet is appropriated by water ; 
 and boiling nitric acid, at 1-34, converts it into Muric Acid. 
 Starch is white, tasteless, brittle, inodourous, formed by boiling- 
 water into a bulky jelly, which by heat is converted into gunv 
 and boiled long in water, with 8 per cent, of diluted sulphuric acid, 
 forms sugar ; it is precipitated by sub-acetate of lead, is by iodine 
 detected in its minutest portions, and is indifferent to alcohol, 
 ether, or cold water. Gluten is tenacious, without odour, hard 
 and brittle when dry, putrefactive when moist and warm, indifferent 
 to water or ether, but appropriated by hot alcohol. Tannin is 
 without colour or odour, but has astringent savour, is appro- 
 priated by ether, hot alcohol, and partially by water ; with acid 
 it forms compounds ; it is precipitated by gelatine, and black by 
 persalts of iron. Wax forms with alkalies, soaps, with oils, 
 cerates, is indifferent to water, but appropriated by ether or hot 
 alcohol, that when cold allows it to deposit ; and Spermaceti 
 much resembles it. Resins are brittle, indifferent to water, but 
 appropriated by alcohol, ether, volatile oils, and alkalies in forming 
 soaps, precipitated by acids, and with wax and oils form ointments 
 and plasters. Fibrin is without odour or savour, indifferent to 
 water ; acetic acid forms it into a bulky jelly, soluble in hot water ; 
 and alcohol at 0*81 converts it to adipocire, soluble in ether and 
 alcohol ; exhibiting nitric acid at 1-2 forms an acid as nitrogen 
 evolves. Albumen has alkaline potency, and coagulates by heat, 
 alcohol, acids, and voltaic circuit : solutions in which it is present 
 obey the exhibiting of prussiate of potash with a little acetic acid 
 corrosive sublimate, tannin, and hypophosphoric acid, but is 
 indifferent to phosphoric or acetic acid. Volatile or Essential 
 Oils dissolve resins, sulphur, and camphor, are inflammable, 
 very aromatic, volatile, and when dropped on paper and warmed 
 the oil disappears. Fixed or Animal and Vegetable Oils 
 have Elain and Stearine as their oily fluid, and white solid com- 
 
 2 Q 
 
-594 OBSERVATIONS. 
 
 ponents, both ofj which are appropriated by hot alcohol, the latter 
 separating when cold, and the former evolving by heating ; with 
 alkalies oils form soaps ; with ammonia, liniments ; and w r ith 
 protoxide of lead, litharge, diachylon ; when dropped on paper 
 and warmed leaves a permanent stain. 
 
 HYDROGEN GAS is colourless, inflammable, supplies a pale 
 iblue flame, intensely hot, but with very little light, the product 
 being only water. Water Vapour, at 212 F., expands 1698 
 'times its volume at its greatest density 39-4; it freezes at 32, 
 'boils at 212, but this diminishes 1 for each 530 feet ascension in 
 ^he atmosphere ; it is '815 times heavier than atmospheric air, and 
 1 cubic inch weighs 252458 grains. Deutoxide of Hydrogen is 
 a very powerful bleaching agent, which decomposes at 59, and 
 explodes when suddenly exposed to a temperature of 212. 
 Olefiant Gas, C 2 H 2 , is appropriated by water to 1-8 its 
 volume, when 2 cl. + 1 oe. gas are exhibited to each other, the 
 result is the oily fluid Hydrocarb. Clorine (see this). The gas 
 C 4 H 4 at 54 liquefies with spec. grav. '627, and vapourises at 
 30. The Bicarburet solidifies at 32, liquefies with spec. grav. 
 -850 at 54, and boils at 186. The Sulphur et is colourless, 
 noisome like rotten eggs, under a pressure of 17 atmospheres 
 liquefies at 50. Water appropriates equal volume, and the 
 action is like acid, and it precipitates metals, as sulphates, from 
 their solutions. The Bisulphuret has a yellow colour, acts as 
 an acid, forming salts. The Protophosphate has an odour like 
 garlic, and water appropriates 1-8 its volume. The Perphosphate 
 has like odour, but when oxygen or atmospheric air is present, 
 spontaneous combustion ensues. 
 
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 OBSERVATIONS. 
 
 AMMONIACAL gas liquefies by a pressure equal to almost 7 at- 
 mospheres ; water solicits 780 volumes, the liquid is colourless, 
 most pungent, destroys vitality, is strongly alkaline, combines and 
 solidifies with muriatic acid gas, and alkalies and alkaline earths 
 solicit it from substances where it is present. The strong liquid 
 ammonia has a specific gravity 9'36, and boils at 130 ; when salts 
 of ammonia, alone or with caustic alkalies, or carbonated ditto, 
 are heated in a glass tube, ammonia evolves, and is recognised 
 by its peculiar odour ; or when very diffuse, by white vapour, 
 caused by the presence of a glass cane moistened with muriatic 
 acid. AMMONIA is indifferent to tartaric acid ; but to chloride of 
 platinum supplies a precipitate yellow, crystalline, ' Most of its 
 salts are appropriated by water, and form crystals ; and some of 
 them without decomposition are by heat rendered volatile. 
 
 THORIUM. When sulphate of potash is present in solution 
 with Thorium, double salts result, which are indifferent to a cold 
 saturated solution of sulphate of potash ; but when this is in 
 excess, and the temperature is raised to 100 F., Thorina is 
 precipitated ; yet it is so extremely rare as to occur very seldom 
 in chemical analysis. Treated with caustic potash and caustic 
 ammonia, its solutions supply a white gelatinous precipitate ; 
 white, flocculent, with phosphate of soda, indifferent to phosphoric 
 acid ; white also with ferrocyanate of potash, hydrosulphuret of 
 ammonia, oxalic acid, and carbonated alkalies (excess of which 
 appropriates the precipitate) ; Thorium is only subject to the 
 concentrated sulphuric acid. Thorina, the oxide, is indifferent 
 to excess of oxalic acid. Sulphate of Thorina is partially appro- 
 priated by concentrated acids, and cold (not hot) water. The 
 blow-pipe flame reduces thorina and borax to a colourless bead, 
 which resists opacity by the flame. 
 
 ZIRCONIUM. Concentrated sulphuric acid appropriates more 
 of this element than any other acid. The neutral solution of 
 zirconium, when boiled with a saturated solution of sulphate of 
 potash, supplies a disalt of zirconia, white ; also by succinated 
 alkalies, by phosphate of soda, by ferrocyanate of potash, hydro- 
 sulphuret of ammonia, oxalic acid (the precipitate appropriated 
 by great excess of muriatic acid), by potash, soda and ammonia ; 
 
OBSERVATIONS. 631 
 
 also by carbonated alkalies (imperfectly precipitated, and slug- 
 gishly appropriated by excess of test). The blow-pipe analysis 
 only with difficulty detects the salts. 
 
 ALUMINUM. The hydrate is precipitated, white, by caustic 
 potash or soda (and excess again appropriates it), caustic ammonia, 
 carbonated alkalies, and hydrosulphuret of ammonia. When 
 needed in quantitative analysis, it is most carefully washed, and 
 all water is evaporated by long incandescense. The hydrate 
 also is by infusion of galls very sluggishly precipitated from 
 solutions in the weaker acids ; and, while indifferent to the 
 succinate and binoxalate of potash, is readily precipitated by the 
 bicarbonate of soda ; it is soluble in caustic potash, from which as 
 a white precipitate it is thrown down by muriate of ammonia 
 and boiling, and likewise by hydrosulphuret of ammonia from 
 neutral solutions, while sulphuretted hydrogen evolves. Alum, 
 in octahedral crystals, is the result of combining sulphates of 
 alumine and potash. The blow-pipe analysis detects alumine, 
 pure or in compounds, by roasting on a charcoal support a small 
 portion of the substance, next adding solution of nitrate of cobalt, 
 and again heating the assay ; the colour appears dirty violet by 
 reflected or candle light, but when cold, is a beautiful blue. 
 
 YTTBIUM forms a double salt with sulphate of potash, by 
 concentrated cold solutions again appropriated, but very slug- 
 gishly, afterwards precipitated, white, also by oxalic acid (indiffe- 
 rent to excess), and to succinated alkalies, potash, soda, phosphate 
 of soda, ammonia, hydrosulphuret of ammonia, and carbonated 
 alkalies (soluble in excess), and greyish white by ferrocyanate of 
 potash, and dirty tvhite by nutgall infusion : also white carbonate, 
 by boiling the solution of yttria and carbonate of ammonia. 
 When the solutions in carbonated alkalies are precipitated, many 
 of the salts are amethystine in colour, and sweetish in savour. 
 The Blow-pipe analysis requires like treatment with alumine for 
 yttria and glucina, and a dark grey or black tint results with the 
 latter, but the former is not easily recognised. 
 
 GLUCINUM. The precipitated hydrate is yelloiv, by treating 
 solutions of the weaker acids with infusion of nutgalls. It does 
 not form a double salt with potash and sulphuric acid. . It is 
 precipitated, white, by potash and carbonated alkalies (soluble in 
 excess of these) ; soda, phosphate of soda, hydrosulphuret of 
 ammonia, also by the succinate, but not the binoxalate of potash; 
 
632 OBSERVATIONS. 
 
 and boiling the solution of carbonate of ammonia precipitates 
 carbonate of glucina ; the salts have a pleasant savour. 
 
 MAGNESIUM in solutions is indifferent to oxalates, and slug- 
 gishly to sulphuric acid ; but supplies a tvhite precipitate to 
 caustic potash, caustic ammonia (when the muriate is absent), and 
 to carbonated alkalies ; the first usually disappears on the exhibi- 
 tion of muriate of ammonia, as likewise always does each of the 
 others, but re-appears when raised to 212 F. ; concentrated 
 solution supplies a while precipitate to carbonated ammonia, and 
 sluggishly to carbonated soda, but not to the bicarbonate ; the 
 precipitated carbonate is readily appropriated by carbonic acid ; 
 the precipitate by phosphate of ammonia is usually, that by 
 binoxalate of potash always, white, crystalline ; also white when 
 plus of alkali is present, to hydrosulphuret of ammonia ; water 
 appropriates the sulphate, and alcohol the nitrate and muriate, 
 which two are deliquescent. The assay heated on a charcoal 
 support, then moistened with solution of nitrate of cobalt, and 
 again highly heated, becomes dull red (or garnet). 
 
 CALCIUM. Solution of lime is indifferent to bicarbonate of 
 soda, and to hydrofluosilicic acid ; but neutral solution supplies a 
 white precipitate to oxalates, crystalline (as gypsuni), in concen- 
 trated, to sulphuric acid and sulphates ; in dilute, to binoxalate 
 of potash, indifferent to water, also to oxalic acid ; but appropriated 
 by plus of nitric or muriatic acid ; the precipitated carbonate is 
 appropriated by plus of carbonic acid. Concentrated solutions 
 supply needles of nitrate or deliquescent chloride, which like the 
 other soluble salts of this base (and those of strontia), when present 
 in inflamed alcohol, cause the flame to be red (or carmine) ; and 
 when the assay w r ith either present is heated at the point of the 
 blow-pipe inner flame, a beautiful faint red (or strong carmine) 
 tint appears until it is fused. 
 
 STRONTIUM, in solution, is indifferent to hydrofluosilicic acid, 
 but supplies a white precipitate to sulphuric acid and sulphates, 
 partially solicited by acids, but not by water, which solicits 
 those supplied to oxalates ; neutral and dilute solutions are slug- 
 gishly troubled by oxalic acid and binoxalate of potash ; the 
 nitrate is indifferent to alcohol, which solicits the muriate. The 
 assay of the chloride by the blow-pipe inner flame has a carmine 
 tint while fusing, evanescent when fused (as in that of calcium). 
 
 BARIUM, in solution, on the exhibition of sulphuric acid or 
 
OBSERVATIONS. 633 
 
 sulphates soluble in water, supplies a precipitate, white, indifferent 
 to water, nitric, or muriatic acid, likewise to binoxalate of potash, 
 phosphates, oxalates, and carbonates, quickly when ammonia is 
 present, and the last class solicited by plus of carbonic acid ; 
 pale lemon yellow to chromates ; a yellow, crystalline, to ferro- 
 cyanate of potash ; and sluggishly, a crystalline to hydrofluosilicic 
 acid. The nitrate and the muriate are indifferent to alcohol. 
 The presence of barytes is with difficulty detected by the blow- 
 pipe. 
 
 LITHIUM supplies salts, which are readily sDlicited by water 
 (except the carbonate and phosphate sluggishly) ; to carbonate of 
 ammonia they give a white precipitate, very minute to tartaric 
 acid ; and yellow, crystalline, to chloride of platinum, the chloride 
 is very deliquescent, and is readily solicited by alcohol. Lithia 
 renders the blow-pipe outer flame carmine red, not affected by 
 potash, but yellow when soda is present, and it solicits and 
 renders yellow the part of the platinum foil on which it is fused. 
 
 SODIUM decomposes water without inflammation, forming 
 soda, which in solutions is indifferent to every re-agent that is a 
 base, but supplies a slight copious opalescent precipitate to 
 hydrofluosilicic acid. The soda salts readily are solicited by 
 water ; the sulphate has prism crystals, grooved, bevelled hexa- 
 gonal ; the nitrate has rhomboids deliquescent ; the chloride has 
 pyramids quadrangular, indifferent to atmospheric action, and 
 solicited by alcohol ; the carbonate has rhomboidal laminae, or 
 decahedrons of two quadrangular pyramids ; like the sulphate, 
 efflorescent. The yellow flame, when the minutest portion is 
 present, renders soda useful as a very delicate test. 
 
 POTASSIUM potently solicits oxygen, and when appropriating 
 that of water, the heat evolved inflames the hydrogen ; concen- 
 trated solutions often sluggishly supply to chloride of platinum a 
 yellow crystalline precipitate, very bright ditto to alcoholic solu- 
 tion of carbazotic acid, and to tartaric acid, ivhite, crystalline 
 (bitartrate of potash). Many of its salts are indifferent to atmos- 
 pheric action. The sulphate has crystals, hexahedral prisms with 
 hexagonal pyramids ; the nitrate has six-sided flattened prisms, 
 with dihedral summits ; the chloride has cubes or rectangular 
 parallel opipedons. The assay fused on platinum wire, and then 
 again heated at the point of the inner flame, renders the outer 
 purple or violet; and the tint is blue when borax and nickel are 
 used. 
 
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OBSERVATIONS. 
 
 SELENIUM has a metallic lustre, and in powder a deep red 
 colour, but neither odour nor savour ; yet when fusing, emits an 
 odour similar to horse-radish in every instance. The Selenious 
 Acid supplies a precipitate, red, to, sulphuric acid, sulphurous 
 acid and zinc (when the temperature is raised) ; white to acetate 
 of lead (sluggishly appropriated by nitric acid), to muriate of 
 barytes (appropriated by muriatic acid), to protonitrate of mercury 
 (appropriated by nitric acid, but indifferent to water), to nitrates 
 of silver and of lime (appropriated by nitric acid) ; and yellow to 
 sulphuretted hydrogen. The Selenites are either completely 
 indifferent to water, or only sluggishly appropriated by it ; but 
 raised temperature decomposes them. On a charcoal support the 
 blow-pipe flame changes them into seleniurets ; or the element 
 evolves, and the peculiar horse-radish odour is perceptible. 
 Selenic Acid is appropriated by water to 512, and above 536 
 is decomposed, and supplies a precipitate of the element to 
 sulphurous acid ; as likewise do the Seleniates after boiling in 
 muriatic acid, which decomposes them, and the selenious acid 
 'evolves. The Hydroselenic Acid, also the Hydroseleniurets of 
 the alkalies and of magnesia (solicited also by nitric acid), are 
 appropriated by water, and appropriating its oxygen and that of 
 the atmosphere, the element precipitates as a red powder ; but the 
 solution supplies one, black, to nitrate of silver, and acetate and 
 protonitrate of lead. 
 
 ARSENIC. The salts of Arseniom Acid supply a precipitate, 
 white, to salts of lead, chlorides of calcium and barium, and lime- 
 water ; green to sulphate of copper ; yellow to nitrate of silver, 
 hydrosulphuret of ammonia, and sulphuretted hydrogen (these two 
 very sluggish in neutral solutions, but remarkably active when 
 acidulated with muriatic acid, and temperature raised) ; and 
 (acidulated) metallic to zinc. The Arsenites fused on a charcoal 
 support by the blow-pipe supply the odour of garlic common to 
 
ti88 OBSERVATIONS. 
 
 metallic arsenic. Klaproth states that 1000 parts of water at 
 the temperature of (60 F.) 12 E. appropriates only 3 parts of 
 Arsenious Acid; but at (212 F.) 80 K. appropriates 73*5, of 
 which 30 remain present after the solution is at (60 F. 12 E. 
 
 CHROMIUM. The protoxide salts are some green, others 
 amethystine ; and the double salts amethystine or blue ; and in 
 either flame of the blow-pipe render the flux emerald green. In 
 solution, ferrocyanate of potash, and also boiling, only renders the 
 tint darker, without causing a precipitate ; they supply a pre- 
 cipitate, green, to alkalies,, caustic and carbonate (those of potash 
 and soda readily, of ammonia sluggishly, in excess re-appropriating 
 the precipitate), indifferent to iron and zinc. After incandescence 
 the protoxide is sluggishly appropriated by acids. Chromic Acid 
 possesses bleaching properties. The salts supply a precipitate, 
 yellow, to salts of lead, lemon yellow to salts of barytes, red brown 
 to salts of silver, and orange to protosalts of mercury (by heat 
 converted into protoxide of chromium). 
 
 VANADIUM. The oxide, by rise of temperature, combines 
 with bases, and is appropriated by acids, the solutions usually 
 being in colour fine azure, the crystals fine blue ; very sluggishly 
 colour water green ; they supply a precipitate, grey white, to 
 potash, soda, and carbonates (which air renders brown) ; brown 
 to ammonia (indifferent to excess, but appropriated by distilled 
 water) ; red brown to carbonate of ammonia ; blue to bicarbonates ; 
 yellow to ferrocyanate of potash (by air rendered green) ; and 
 black to infusion of galls and hydrosulphuret of ammonia. 
 Vanadic Acid fuses at a red heat, orange ; is resolved into oxide 
 by sugar and alcohol ; is readily at raised temperature appropriated 
 by muriatic acid (orange coloured) ; and sluggishly by water, 
 sulphurous, nitrous, and vegetable acid. When mixed with borax, 
 or microcosmic salt, and on charcoal fused by the blow-pipe, the 
 bead in the interior flame appears brown, and the exterior yellow, 
 but fine green when cold, unless by the presence of tin rendered 
 blue. 
 
 MOLYBDENUM. The oxide salts in solution are red brown, 
 and become blue by raised temperature and appropriating the 
 oxygen of the air ; they supply a precipitate, rust brown or 
 chocolate, to alkalies, caustic and carbonate, brown to hydrosul- 
 phuret of ammonia and sulphuretted hydrogen, very dark to 
 ferrocyanate of potash, and grey to infusion of galls. Molybdic 
 
OBSERVATIONS. 689 
 
 Acid can be by any of the strong acids separated from the alkalies 
 with which it is combined. 
 
 TUNGSTEN. Tungsiic Acid is separated, likewise, by either 
 nitric or muriatic acid, and is yellow when dry ; it is readily 
 appropriated by alkalies, but sluggishly by acids, and the portion 
 too minute to form salts ; tin appropriates a portion of the oxygen, 
 and the blue residuum is supposed to be a mixture of the oxide 
 and tungstic acid. 
 
 ANTIMONY. The oxide is indifferent to nitric acid, is appro- 
 priated readily by nitro muriatic acid, sluggishly by muriatic acid, 
 which to water supplies a white precipitate, appropriated by dilute 
 acid. The oxide salts (except the double) supply a precipitate, 
 white, to water, the strong acids, the alkalies, caustic and 
 carbonate, and solution (not crystal) of ferrocyanate of potash ; 
 orange to hydrosulphuret of ammonia, soluble in excess, and 
 sulphuretted hydrogen. Most of the hydrated precipitates are 
 indifferent to water, but appropriated by tartaric acid. On a 
 charcoal support, with soda fused, the blow-pipe flame reduces the 
 salt to a button of metallic antimony, when cold coated with white 
 crystals of protoxide. 
 
 TELLURIUM, in solution, of nitric acid is indifferent to the 
 addition of pure water ; but of muriatic acid, supplies a precipitate, 
 ivhite, to alkalies, caustic and carbonate (by excess re -appropriated, 
 element and salts) : and metallic, to zinc, tin, copper, iron, sul- 
 phurous acid, and sulphite of ammonia. The oxide is appropriated 
 by nitric and muriatic acids ; forms salts with acids and alkalies, 
 with hydrogen forms a colourless gas, by water appropriated, 
 claret colour, and sulphuretted hydrogen odour ; at a red heat 
 effervescing, fusing, and afterwards sublimed. 
 
 TANTALUM. The protoxide (with difficulty determined by 
 the blow-pipe) when incandesced is indifferent to acids, which, 
 while raw, affect it sluggishly ; the hydrate is readily appropriated 
 by fluoric and oxalic acids ; the latter to ferrocyanate of potash 
 supplies a yellow precipitate. The (peroxide) Tantalic Acid, 
 combined with alkalies, supplies a precipitate, ivhite, to the strong 
 acids and tin ; likewise, flocculent, to alkalies, caustic and 
 carbonate, orange to infusion of galls, and many of them to 
 water. 
 
 TITANIUM. The oxide (not readily detected by the blow- 
 pipe in solution acid) supplies a precipitate, dark olive-green, to 
 
 2 Y 
 
690 OBSERVATIONS. 
 
 ferrocyanate of potash. Boiling the chloride precipitates the 
 oxide in so comminute a state that it easily permeates the filter ; 
 the solution, prior to boiling, when treated with zinc, is first 
 violet, next blue, and then supplies a slate blue precipitate ; and 
 with tin is amethystine, and then follows a brown red precipitate. 
 Boiling the muriatic solution of Titanic Acid supplies a copious 
 precipitate, indifferent to hydrosulphuret of ammonia ; but the 
 acid, prior to boiling, supplies one, white, to alkalies, caustic and 
 carbonate, dark green to hydrosulphuret of ammonia, copper 
 coloured to ferrocyanate of potash, orange to infusion of galls, 
 and purple to zinc bar. 
 
 SILICIUM. The oxide (Silica or Silicic Acid) is indifferent 
 "to every acid and to water, except the hydrofluoric, with which it 
 forms silicated fluoric acid gas ; yet they sluggishly appropriate 
 part of the hydrate, and (even when dilute) readily all the fresh 
 precipitated jelly of silica obtained from the solutions by alkalies 
 and carbonate of ammonia ; decomposed by ammonia, also by 
 boiling dry an acid solution, and to the dry mass adding muriatic 
 acid ; and by incandescence rendered indifferent to water and 
 acids, except the phosphoric and boracic. With soda on a 
 charcoal support it (and it only) will form a bead perfectly clear, 
 and indifferent to mic. salt, in which it floats about. 
 
 OSMIUM. By boiling, the oxide volatilises as the salts de- 
 compose ; water readily appropriates it, and applied to the skin, 
 stains it indelible to washing ; by sulphuric acid is decomposed, 
 the liquid being in colour successively yellow, brown, green, and 
 blue ; yellow by ammonia, primrose by carbonate of soda, purple 
 to beautiful blue by infusion of galls ; the solution supplies a 
 precipitate, black ; flocculent to alcohol and ether ; and black to 
 hydrosulphuret of ammonia and sulphuretted hydrogen ; the 
 peroxide is volatile, and easily sublimes. 
 
 GOLD is very malleable, green by transmitted light, not 
 oxidated by heat, appropriated by chlorine ; mixed with soda 
 on charcoal support easily reduced by blow-pipe flame, and 
 purified by cupellation and quartation. The solution supplies 
 a precipitate, a mixture of calomel and metallic gold, to 
 protonitrate of mercury ; red purple, followed by Cassius' 
 powder, a dark red powder, to protomuriate of tin ; emerald 
 green to ferrocyanate of potash ; yellow, sluggishly and partially, 
 to alkalies, caustic and carbonate, brown to hydrosulphuret of 
 
OBSERVATIONS. 691 
 
 ammonia; but readily, in a metallic state, to zinc, iron, tin, 
 several other metals, oxalates, protosulphate of iron, sulphuretted 
 hydrogen, phosphorus, sulphurous, and oxalic acids. 
 
 IRIDIUM, when platinum is present, is sluggishly appropriated 
 by nitro-muriatic acid ; and alone, extremely sluggishly, in com- 
 parison sixteen times more so than platinum, and three hundred 
 times more so than gold; the liquid is iridescent, with a brown 
 or tjreen tinge, or red, with water ; but is rendered colourless by 
 sulphuretted hydrogen and alkalies ; is indifferent to infusion of 
 galls, ferrocyanate of potash, and carbonate of soda ; but supplies 
 a precipitate, red brown, to muriates of potash and ammonia, 
 and carbonate of ammonia, crystalline, to caustic alkalies, and 
 dark brown to sulphuretted hydrogen and hydrosulphuret of 
 ammonia, and metallic by the oxidable metals, but not by gold 
 and platinum. 
 
 KHODIUM. The Oxide is appropriated by most strong acids, 
 and the solution supplies a precipitate, yellow, to caustic alkalies 
 (re-appropriated by excess), and brown to hydrosulphuret of 
 ammonia and sulphuretted hydrogen, and one, metallic, to the 
 oxidable metals indifferent to gold and platinum. The soda 
 chloride is indifferent to alcohol, but readily appropriated by 
 water. 
 
 PLATINUM is appropriated only by nitro-muriatic acid ; and 
 the solution supplies a double chloride to potash and ammonia, 
 and ferrocyanate of potash ; and a precipitate, brown, to iodide of 
 potassium, hydrosulphuret of ammonia, and sulphuretted hydrogen 
 (appropriated by excess) ; yellow red to protonitrate of mercury, 
 yellow to prussiate of potash, and crystalline to the alkalies, 
 caustic (appropriated by excess) and carbonate ; metallic to 
 the readily oxidated metals, but indifferent to gold and silver, 
 cyanuret of mercury, and protosulphate of iron, is coloured deep 
 red brown by protomuriate of tin ; the double salts with potash 
 and ammonia is sluggishly appropriated by water, yet indifferent 
 to alcohol, while both readily appropriate that with soda ; and that 
 with ammonia, when at a high temperature, supplies the metal in 
 a very tine spongy state, employed to ignite hydrogen gas. With 
 the usual fluxes, the blow-pipe flame forms a button of metal, 
 without discolouring the solvents. 
 
 PALLADIUM. The oxide is appropriated by nitric acid, the 
 solution being a beautiful red ; and water appropriates most of 
 
 2 Y 2 
 
69'2 OBSERVATIONS. 
 
 the salts, likewise a beautiful red, and supplies a precipitate, 
 black or olive green, to protomuriate of tin, yellow brown to 
 ferrocyanate of potash, yellow ivhite to cyanuret of mercury, 
 brown to hydrosulphuret of ammonia and sulphuretted hydrogen, 
 orange (when dry, black) to alkalies, caustic and carbonate, 
 metallic to protosulphate of iron, and all the oxidable metals 
 except silver, gold, and platinum. The double chlorides with the 
 alkalies are indifferent to alcohol. 
 
 MERCURY.- The protoxide solution supplies a precipitate, 
 white, to the alkalies, caustic (and carbonate, when muriate of 
 ammonia is present, otherwise it is black), phosphate of soda, 
 ferrocyanate of potash, binoxalate of potash, scarlet red to 
 chromate of potash, greenish yellow to iodide of potassium (or 
 excess black, and by great excess re-appropriated), yellow to 
 hydriodates, black to sulphuretted hydrogen and caustic alkalies, 
 white to muriatic acid (indifferent to nitric acid, black by presence 
 of ammonia), white to black, to carbonate of ammonia, and 
 yellowish white to grey to carbonate of potash or soda, and 
 metallic (of the peroxide likewise) to zinc, iron, copper, sul- 
 phurous, and phosphorous acids ; by the galvanic circuit, also the 
 protomuriate of tin, to a grey powder, by heat formed into a 
 globule of metal. Both oxides often being present in the nitric 
 solution, the precipitates are mixed, the alkaline usually plus of 
 peroxide, and the colours varied with plus of either. The oxide 
 (Mr 4 O) supplies a precipitate, dirty yellow, to infusion of galls, 
 to the peroxide, orange yellow ; white (both) to ferrocyanate of 
 potash and caustic ammonia, grey (white) to carbonate of 
 .ammonia (the precipitate by ammonia being re-appropriated as 
 formed) ; dirty green (lemon yellow) to caustic potash and soda, 
 pale yellow or greenish to carbonate potash, and soda (red brown), 
 and black (both) to hydrosulphuret of ammonia and sulphuretted 
 hydrogen ; and when muriate of ammonia is present, yellowish 
 red (in concentrated solutions) to chromate of potash, indifferent to 
 muriatic acid, cinnabar red to iodide of potassium (re-appropriated 
 by excess), white to potash and phosphate of soda, black to 
 hydrosulphuret of ammonia carefully added and sulphuretted 
 hydrogen, by agitation ivhite, by excess very black. The salts of 
 all the oxides are by heat volatile ; and when mixed with either 
 black flux or dry soda, and in a test tube exhibited to the blow- 
 pipe flame, the mercury sublimes as a grey powder, which by 
 trituration supplies globules of the metal. 
 
OBSERVATIONS. 693 
 
 SILVER is not oxidated by heat or air, nor absorbed by the 
 bone-earth cupel used to separate other metals (except gold and 
 platinum, which require quartation) ; but the .blow-pipe flame 
 applied to a mixture of the oxide and soda on a charcoal support 
 supplies the metal as a bright button. The solution of the oxide 
 supplies a precipitate, white, ftocculent to muriatic acid, violet in 
 air, indifferent to nitric acid, but readily appropriated by ammonia ; 
 yet neither solicit the yellow white to iodide of potassium, and 
 both appropriate the egg-yellow to phosphate of soda, dark 
 chocolate to chromate of potash, yellow brown to infusion of galls 
 and caustic alkalies, ivhite to carbonate alkalies and ferrocyanate 
 of potash, black to hydrosulphuret of ammonia and sulphuretted 
 hydrogen, and metallic to iron, zinc, copper, and (as an amalgam) 
 to mercury. 
 
 COPPEK. The protoxide is solicited by only few acids, and 
 the almost colourless solutions formed readily appropriate the 
 oxygen of the air, and supply a precipitate, blue to alkalies, 
 caustic and carbonate, appropriated by excess, red to ferrocyanate 
 of potash, yellow grey to red ferrocyanate, black to hydrosulphuret 
 of ammonia and sulphuretted hydrogen ; but used prior to 
 exposure to the air, yellow to caustic alkalies, and primrose to the 
 carbonated (appropriated by excess, and the solutions colourless), 
 dark brown to hydrosulphuret of ammonia and sulphuretted 
 hydrogen, and metallic to iron, zinc, tin, indifferent to sulphuric 
 or muriatic acid. Nitric acid readily appropriates it, forming a 
 deutoxide, by iron and zinj reduced to the metallic state. Boiling 
 the hydrated deutoxide with caustic potash supplies a black 
 deutoxide, which (in neutral solutions, and those of the weaker 
 acids) supplies a precipitate, blue to caustic potash and soda, 
 greenish blue to ammonia and carbonated alkalies, brown to 
 infusion of galls, red brown to ferrocyanate of potash, dark brown 
 to hydrosulphuret of ammonia and sulphuretted hydrogen, and 
 metallic to zinc and iron. The salts mixed with soda on a 
 charcoal support by the blow-pipe flame readily form a button of 
 metal ; but with borax, or mic. salt, a glass bead, in the interior 
 flame red brown, and in the exterior dark green. 
 
 URANIUM. The protoxide is dark green, and becomes black 
 on procelain, while the orange peroxide preserves its tint thereon. 
 The protoxide salts in solution are pale green, and when imme- 
 diately used supply a precipitate, green to alkalies, caustic and 
 
694 OBSERVATIONS. 
 
 carbonate, the latter appropriated by excess, and indifferent to 
 carbonate of soda ; but when exposed to light and air, or treated 
 Avith nitric acid, changed into the peroxide, yellow, indifferent to 
 iron, zinc, or tin ; but which supplies a precipitate, orange to 
 alkalies, caustic and carbonate, red to ferrocyanate of potash; and 
 black to hydrosulphuret of ammonia. 
 
 BISMUTH. The oxide, yellow, is indifferent to sulphuric 
 acid ; the neutral salts are appropriated by water to a determined 
 degree, and then plus of water causes a precipitate ; the chloride 
 solutions deposit a small portion of dichloride ; the precipitate 
 supplied is white to alkalies, caustic and carbonate, also car- 
 bonates of lime and magnesia, cold or boiling ; yellow to infusion 
 of gallSj chromate, and ferrocyanate of potash, brown to iodide 
 of potassium, dark brown to red ferrocyanate of potash, hydrosul- 
 phuret of ammonia, and sulphuretted hydrogen, and metallic to 
 zinc or copper bar. By the interior blow-pipe flame, a brittle, 
 easily broken metal button is formed of the salts mixed with 
 soda, on a charcoal support, which appropriates a yellow powder 
 coating. 
 
 TIN, though indifferent to the strongest nitric acid, is very 
 powerfully solicited thereby on adding a little water. The 
 protoxide salts in solution supply a precipitate, white, to muriatic 
 and oxalic acids, to both ferrocyanates of potash, to phosphate of 
 soda, to the alkalies, caustic and carbonate (that to ammonia by 
 excess appropriated), brown to hydrosulphuret of ammonia, and 
 sulphuretted hydrogen, yellow, to these two, of peroxide salts, 
 but the colours of the others are alike to both oxides, metallic to 
 zinc bar, and solution of silver, platinum, and gold (the Cassius' 
 purple}, and appropriates oxygen from solution of iron, copper, 
 or mercury, which oxide is solicited by zinc. The incandesced 
 peroxide of tin is indifferent to all acids, except muriatic ; the solu- 
 tion is indifferent to the solution of gold, and supplies a precipitate, 
 metallic to zinc bar, yellow stiff jelly to ferrocyanate of potash, 
 indifferent to muriatic acid ; and those to this last and the caustic 
 alkalies, by excess most sluggishly re-appropriated. The salts 
 with soda, on a charcoal support, by the interior blow-pipe flame 
 are formed into a malleable button, by the exterior flame easily 
 oxidated. 
 
 LEAD. The protoxide supplies a precipitate, yellow, to 
 alkalies, caustic and carbonate, and at 212 to carbonate of 
 
OBSERVATIONS. 695 
 
 lime, to chromates and hydriodates ; white to sulphuric acid 
 and soluble sulphates (sluggishly appropriated by nitric acid), to 
 alkalies, caustic and carbonate, crystalline to muriatic acid, 
 appropriated by much water, and dilute nitric acid, curdy to 
 muriates, appropriated by boiling water, and crystallising when 
 cooling, black to hydrosulphuret of ammonia, and sulphuretted 
 hydrogen, and metallic to zinc. The vegetable acid salts in 
 solution mostly are indifferent to ammonia, or else this appro- 
 priates the lead as the solution is decomposed. The salts mixed 
 with soda, or borax, on a charcoal support, by the blow-pipe flame 
 is easily reduced to a button of malleable lead. 
 
 CEKIUM. The protoxide salts are sluggishly appropriated by 
 water ; the solutions supply a precipitate, white, to alkalies, 
 caustic and carbonate (appropriated by excess), phosphate of soda, 
 oxalates, ferrocyanate of potash, infusion of galls, and (in neutral 
 solutions) hydrosulphuret of ammonia, oxalates, oxalic acid 
 'indifferent to excess) ; crystalline to sulphate of potash, indifferent 
 to excess ; and the common peroxide is fawn colour, while that 
 by the blow-pipe exterior flame, from the salts with borax, or mic. 
 salt, is red brown, but colourless in the interior, and likewise 
 when cold. 
 
 COBALT. The protoxide salts are red, and acid solution 
 supplies a precipitate green to ferrocyanate, red-brown to red ferro- 
 cyanate, and pale rose to binoxalate, of potash (sluggishly in air, 
 re- appropriated by ammonia, caustic and carbonate), blue to ash 
 to caustic alkalies and oxalates (appropriated by ammonia), 
 indifferent to oxalic acid, pink to carbonated alkalies, black to 
 hydrosulphuret of ammonia ; but (likewise nickel salts) indifferent 
 to carbonate of lime or magnesia, and bar of zinc or iron. Chlorine 
 gas readily converts the protoxide in solution in water to peroxide ; 
 the chloride solution is rose-red concentrated blue and very 
 dry, rose-red. The blow-pipe flame forms the salts and borax or 
 mic. salt into a rich strong blue bead. 
 
 NICKEL salts are beautiful green, except the evaporated dry 
 chloride orange. The oxide, in ammonia, supplies a precipitate to 
 caustic potash, this differing from cobalt ; is likewise readily by 
 chlorine gas converted into peroxide, much appropriated by the gene- 
 rated muriatic acid ; the acid solution is indifferent to ammonia, 
 but supplies a precipitate, black, to hydrosulphuret of ammonia, 
 whitish to infusion of galls, light green to grey to ferrocyanate, 
 
696 OBSERVATIONS. 
 
 and yellow to red ferrocyahate of potash, apple green to alkalies, 
 caustic and carbonate (excess appropriating the ammoniates, the 
 caustic liquid violet, the carbonate green], to oxalates, and 
 binoxalate of potash, indifferent to oxalic acid, but appropriated 
 by ammonia, caustic and carbonate ; and neutral solutions (cobalt 
 also, most sluggishly), black to sulphuretted hydrogen. The 
 blow-pipe flame forms the potash salts, with borax, into a blue 
 bead, the others, red while hot, which fades, or entirely disappears, 
 when cold. 
 
 IRON. The salts appropriate oxygen rapidly from any me- 
 dium ; those of the protoxide are green, appropriated by carbonic 
 acid (magnetic), and soliciting the oxygen of solution of gold 
 leaves the metal to precipitate ; at 60 F. indifferent to benzoates, 
 ^uccinates, also carbonate of lime or magnesia, each of which, at 
 any temperature, solicits the peroxide, whose salts are red brown, 
 as likewise are the precipitates they supply to alkalies, caustic and 
 carbonate. The protoxide supplies a precipitate, white, to alkalies, 
 caustic and carbonate, which rapidly becomes dark brown by 
 appropriating the oxygen of the air, blue to ferrocyanate of 
 potash (prussian blue), pale to the peroxide, in proportion to the 
 oxygen, purple to bhie, sluggishly to infusion of galls, black to 
 hydrosulphuret of ammonia (likewise peroxide), and (neutral) 
 sluggishly to sulphuretted hydrogen (the sulphur falling to 
 peroxide), also of the other oxides, when much of the test is used ; 
 the second oxide supplies a precipitate to the alkalies, caustic 
 and carbonate, green, varying in tint with the proportion of 
 peroxide ; this last supplying a precipitate, dark blue (ink colour) 
 or blue black to infusion of galls, and blood red, not magnetic, to 
 sulphocyanic and meconic acids. The salts with borax, or mic. 
 salt, on charcoal support, by blow-pipe exterior flame forms a bead 
 deep red, green in interior, yet only pale when cold, even with 
 plus of iron. 
 
 CADMIUM, at a raised temperature, is almost equally as 
 soluble as mercury ; the oxide, after incandescence, is orange 
 brown, and when obtained in platinum vessel, can be well washed 
 on the sides, to which it adheres. The oxide solution supplies a 
 precipitate, white to alkalies, caustic and carbonate, and ferrocya- 
 nate, and binoxalate of potash, yellow to red ferrocyanate and 
 infusion of galls, orange to hydrosulphuret of ammonia and 
 sulphuretted hydrogen, distinguished from orpiment by fusing 
 
OBSEEVATIONS. 697 
 
 into metal, and metallic to zinc. The salts mixed with soda, by 
 the blow-pipe flame fused on charcoal, stains it and covers it with 
 a brown-red powder. 
 
 ZINC, in oxide, heated is yellow, cold white ; and in solution 
 supplies a precipitate, ivhitc, to alkalies, caustic and carbonate 
 (appropriated by excess), to binoxalates (indifferent to oxalic acid), 
 to ferrocyanate of potash, infusion of galls, hydrosulphuret of 
 ammonia, and (when neutral) to sulphuretted hydrogen. The 
 salts mixed with soda, or nitrate of cobalt, by blow-pipe flame is 
 fine green, on charcoal, coated ivhite in exterior, and spread over 
 the surface in the interior flame. 
 
 MANGANESE, in protoxide pale rose-red, peroxide red (formed 
 by chlorine gas applied to the former) not appropriated by car- 
 bonic acid. The protoxide supplies a precipitate, white, to alka- 
 lies, caustic and carbonate (broivn by peroxide), and air quickly 
 rendering the former brown, while those of the bicarbonate re- 
 main white, indifferent to carbonate of lime and magnesia, but 
 appropriated by carbonic acid and ammonia ; brown to chloride 
 of lime, and of sulphur to sulphuretted hydrogen. Fusion with 
 carbonate of potash, or nitrate of potash, forms the mineral 
 chamelion ; and with borax, or mic. salt, on charcoal, the 
 exterior flame of blow-pipe forms a bead amethystine, invisible 
 in the interior, but when cold re-appearing. 
 
r>98 
 
 ISOMORPHISM, ISOMERISM, ETC. 
 
 There are numerous proofs to warrant the conclusion of the 
 most experienced chemists of our day, that the primary figure 
 is the same of the atom of certain classes of acids, bases, and 
 elements, which consequently may replace, or be substituted 
 for, each other, without altering the figure of the crystal of the 
 resulting compound. These classes originate the following 
 Groups, arranged to shew already determined connecting links ; 
 in which every member of each, whether binary or other com- 
 pound, which replaces another, has identity of the number of 
 atoms in the whole, and of the respective component elements ; 
 equal numbers of which replace each other, yet the crystalline 
 figure remains the same by combinative potency. 
 
 (The Groups are from PROFESSORS MILLER and JOHNSON ; 
 and the arrangement of substances and notation are altered to 
 agree with the previous Tables. For these and the additions (*),. 
 I must bear the liability of error.) 
 1. 
 
 Chlorine f 
 
 Bromine 
 
 Iodine ... 
 
 Fluorine t ... 
 
 Manganese 
 
 (t Cl 2 and F 2 , Berzelius) 
 
 2. 
 
 Chloric Acid 
 Bromic Acid 
 lodic Acid 
 
 Hyperchloric Acid 
 Hypermanganic Acid 
 
 4. 
 
 Sulphur 
 Selenium .. 
 Chromium 
 Vanadium?.. 
 Manganese 
 
 
 5. 
 
 
 Cl 
 
 Peroxide of Lead , ... 
 
 Pb 4 O 3 
 
 ... Bm 
 
 -r 
 
 Fe 4 O :i 
 
 .Lron . . . 
 
 I 
 
 Manganese 
 
 Mn 4 0- 
 
 ... F 
 
 C* 1 H- 
 
 Co 4 3 
 
 OOUcllu 
 
 Mn 
 
 - Nickel 
 
 Ni 4 O 3 
 
 
 Zinc 
 
 Zn 4 O 3 
 
 
 Conner 
 
 Cu 4 :i 
 
 
 
 Magnesia ... .'... 
 
 Mg 4 0"? 
 
 HC1O 3 
 
 Lime 
 
 Ca 4 3 ? 
 
 
 6. 
 
 
 HIO 3 
 
 Sulphuric Acid ... 
 
 HSO 2 
 
 
 Selenic Acid 
 
 HSeO 2 
 
 HC1O 
 
 Chromic Acid 
 
 HCrO 2 
 
 HMnO 
 
 Vanadic Acid 
 
 HVO 2 
 
 
 Manganic Acid ... 
 
 HMnO 2 
 
 
 7. 
 
 
 S 
 
 Green Oxide of Chromium 
 
 Cr 4 3 
 
 ... Se 
 
 Red Oxide of Iron 
 
 Fe 4 O 3 
 
 Cr 
 
 Brown Oxide of Manganese 
 
 Mn 4 O 3 
 
 ... V 
 
 Alumine 
 
 A1 4 O S ? 
 
 Mn 
 
 Titaniate of Protox. of Iron 
 
 Fe n TiO 3 
 
ISOMOBPHOUS GROUPS. 
 
 699 
 
 8. 
 
 
 14. 
 
 
 Platinum 
 
 Pt 
 
 Potash ... 
 
 K 2 3 
 
 Copper 
 
 ... Cu 
 
 Ammonia t ... 
 
 AmZO 3 
 
 Bismuth 
 
 Bi 
 
 (t Am 2 + Aq 2 Berzelius) 
 
 
 Lead 
 
 ... Pb 
 
 15. 
 
 
 Cobalt ... 
 
 ... Co 
 
 
 
 Nickel 
 
 ... Ni 
 
 Ammonia 
 
 H*Z 2 ? 
 
 Zinc 
 
 Zn 
 
 Arseniuretted Hydrogen 
 
 H 3 As 2 
 
 Iron 
 
 ... Fe 
 
 Phosphoretted Hydrogen 
 
 ppps 
 
 Manganesium 
 
 Mn 
 
 
 
 
 
 ^nrlfl 
 
 
 Aluminum ... ... 
 
 .:. AI 
 
 ootia ... ... ... 
 
 
 Magnesium 
 
 ... ' Mg 
 
 Oxide of Silver 
 
 Ag 2 
 
 Calcium 
 
 ... Ca 
 
 16. 
 
 
 9. 
 
 
 Sodium 
 
 N 
 
 Barium... 
 
 Ba 
 
 Silver 
 
 ... Ag 
 
 
 
 Gold 
 
 An 
 
 Strontium 
 
 ... Sr 
 
 
 
 Calcium 
 
 Ca 
 
 And probably all other electro-posi- 
 
 Lead 
 
 ... Pb 
 
 tive Metals whose crystals have 
 
 
 
 regular form. 
 
 
 10. 
 
 
 17. 
 
 
 Lime 
 
 Ca 2 
 
 Molybdic Acid ... 
 
 Mo 2 O 3 
 
 Barytes 
 
 Ba-0 
 
 Tungstic Acid 
 
 W 2 O 3 
 
 Strontian 
 
 Sr 2 O 
 
 
 
 Yellow Oxide of Lead 
 
 Pb 2 O 
 
 18. 
 
 
 
 
 Protoxide of Iron 
 
 Fe 2 
 
 11. 
 
 
 Green ditto Manganesium 
 
 Mn 2 O 
 
 Phosphorus 
 
 P 
 
 Brown ditto Chromium ... 
 
 Cr 2 
 
 Arsenic 
 
 ... As 
 
 Alumine 
 
 A1 2 O 
 
 Antimony 
 
 ... ,. Sb 
 
 Glucine 
 
 Be >2 
 
 Tellurium ... 
 
 ... Te 
 
 * Magnesia ... 
 
 Mg^ 
 
 
 
 *Yttria 
 
 Y 2 
 
 12. 
 
 
 
 
 
 
 * Zirconia ... 
 
 Zr 2 O 
 
 (*) Phosphorus Acid 
 
 P 4 O :i 
 
 *Thoria 
 
 Th' 2 O 
 
 Arsenious Acid 
 
 As 4 O 3 
 
 
 
 Antimonious Acid 
 
 ... Sb 4 3 
 
 19. 
 
 
 
 
 Platinum 
 
 Pt 
 
 Phosphoric Acid . . . 
 
 ... P 4 5 ? 
 
 Palladium ... 
 
 ... Pd 
 
 Arsenic Acid 
 
 As 4 O 5 ? 
 
 Iridium 
 
 Ir 
 
 Antimonic Acid 
 
 ... Sb 4 5 ? 
 
 Osmium 
 
 ... Os 
 
 
 
 Iron 
 
 Fe 
 
 13. 
 
 
 Copper 
 
 ... Cu 
 
 Oxide of Tin 
 
 *;. : Sn 2 O 
 
 Bismuth 
 
 Bi 
 
 Titanic Acid 
 
 Ti 2 O 
 
 Lead 
 
 ... Pb 
 
700 
 
 ISOMORPHOUS GROUPS. 
 
 20. 
 
 Proto Sulphate of Copper CuSO 2 
 
 Sulphate of Magnesia t 
 
 and Nickel, 
 MgSO- | CuNiSO 2 
 
 Zinc 
 
 ZnSO' 
 
 ! AT 
 
 Magnesia, 
 
 Seleniate of Zinc 
 
 ... ZnSO* 
 
 CuMgSO 2 
 
 Sulphate of Nickel ... 
 
 NiSO- 
 
 I7inp 
 
 (t MgHS0 10 , Beudant) 
 
 
 CuZnSO 2 
 
 21. 
 
 . 
 
 rj\^ J 11;!- 
 
 Ziinc and M.agnesia, 
 
 Sulphate of Soda 
 
 ... NSO- 
 
 ZnMgSO 2 
 
 Seleniate of Soda 
 
 NSeO- 
 
 
 
 Sulphate of Silver 
 
 ... AgSO 5 
 
 ganese MgMnSO 2 
 
 Seleniate of Silver 
 
 AgSeO- 
 
 Seleniate of ditto ... NSeO 2 
 
 22. 
 
 
 Chromate of ditto ... NCrO 2 
 
 Sulphate of Lime 
 
 ... CaSP' 
 
 28 
 
 Seleniate of Lime 
 
 CaSeO 2 
 
 ^lO. 
 
 
 
 Double Sulphates. 
 
 23. 
 
 
 Potash Sul. of Magnesia KMgSO 2 
 
 Sulphate of Ammonia 
 
 ... AmSO- 
 
 Ammonia ditto ... AmMgSO 2 
 
 -Potash .... 
 
 KSO- 
 
 Potash ditto Manganese KMnSO 2 
 
 Seleniate of ditto 
 
 ... KSeO 2 
 
 Ammonia ditto ... AmMnSO 2 
 
 Chromate of ditto 
 
 KCrO- 
 
 Potash Sulphate of Iron KFeSO 2 
 
 Manganate of ditto 
 
 .. KMnO 5 
 
 Ammonia ditto ... AmFeSO 2 
 
 *Hyponitrite of ditto 
 
 KZO> 
 
 Potash Sul. of Nickel ... KNiSO 2 
 
 * Oxalite of ditto 
 
 KCO 2 
 
 Ammonia ditto ... ArnNiSO 2 
 
 24. 
 
 
 Potash Sulphate of Zinc KZnSO 2 
 
 Hyperchlorate of Potash . . . KC1O 
 Hypermanganate of ditto KMnO 
 Hyperchlorate of Ammonia AmCIO 
 Hypermanganate of ditto AmMnO 
 
 Ammonia ditto ... AmZnSO 2 
 Potash Sul. of Cobalt . . . KCoSO 2 
 Ammonia ditto ... AmCoSO 2 
 Potash Sul. of Uranium ... KUSO 2 
 Ammonia ditto ... AmUSO 2 
 
 25. 
 
 
 Potash Sul. of Copper ... KCuSO 2 
 
 Sul. of Silver & Am 
 
 AmAgSO' 2 
 
 Ammonia ditto ... AmCuSO 2 
 
 Seleniate of do. do. ... 
 
 SeAgSO' 2 
 
 * Potash Sul. of Silver ... KAgSO 2 
 
 Chromate of do. do. 
 
 ..CrAgSO 2 
 
 * Ammonia ditto . . . AmAgSO 2 
 
 
 
 * Potash Sul. of Platinum KPtSO 2 
 
 26. 
 
 
 * Ammonia ditto ... AmPtSO 2 
 
 Sulphate of Nickel . 
 
 .. NiSO 2 
 
 *Soda ditto ... NPtSO 2 
 
 Seleniate of do. 
 
 NiSeO- 
 
 
 Zinc ... 
 
 .. ZnSeO-' 
 
 29. 
 
 
 
 * Potash Sul. of Manganese KMnSO 
 
 27. 
 
 
 Ammonia ditto ... AmMnSO 
 
 Protosulphate of Iron 
 
 .. FeSO' 2 
 
 Potash do. Zinc ... ... KZnSO 
 
 A*v*rvr\niQ /liffrk A wv *7 v\ G C\ 
 
ISOMORPHOUS GROUPS. 
 
 701 
 
 Potash ditto Cadmium 
 
 . KCdSO Ammonia Chloride of Lead AmPbCl 
 
 AiYnnoni&i clitto 
 
 VmCdSO n/vrrt. 
 
 AmCufl 
 
 Potash ditto Iron . . 
 
 . KFeSO 
 
 
 AmAgCl 
 
 OllVcI: 
 
 A ' A'4-4- 
 
 Am"FVSO i TM"*v-/Tiit 
 
 ArnMrfll 
 
 Ammonia QITJIJO 
 Ammonia ditto 
 
 Aim? fcJovy I 
 
 AmNiSO 
 
 O-mium 
 
 -AUllYlIOl 
 
 AmlrC! 
 
 Iridium 
 
 
 Potash ditto Cobalt 
 
 . KCoSO 
 
 T^nllifHi 
 
 im, 
 
 
 Ammonia ditto 
 
 AmCoSO 
 
 AmPdCl 
 
 Potash ditto Cerium 
 
 . KCoSO 
 
 JrlL til Hill 
 
 
 
 Ammonia ditto Tin ... 
 
 AmCaSO ; 
 
 AmPtCl 
 
 Potash ditto Silver 
 
 . KAgSO 
 
 
 Ammonia ditto 
 
 Am \gSO Potash do. Osmium 
 
 KOs 2 Cl 3 
 
 
 Iridium 
 
 . KIr 2 Cl 3 
 
 30. 
 
 Palladium 
 
 KPd 2 Cl 3 
 
 Anhydrite 
 
 . CaSO 2 
 
 Platinum 
 
 KPt 2 CP 
 
 Heavy Spar ... 
 
 BaSO'- 
 
 _; 
 
 
 Celestine 
 
 .. SrSO 2 
 
 Soda Chloride of Gold . 
 
 .. NAnCl 
 
 Sulphate of Lead 
 
 PbSO 2 
 
 R<hodium 
 
 NRC1 
 
 '* Lithia 
 
 LSO 2 
 
 
 "KTT-M/^ll 
 
 Glucina 
 
 BeSO 2 
 
 Iridium 
 
 JNlrul 
 
 "NTT)4-r^1 
 
 * Zirconia 
 
 ZrSO 2 
 
 Platinum 
 
 JNr'tUl 
 
 
 
 34. 
 
 
 31. 
 
 
 Native Antimony ' , 
 
 Sb 
 
 
 
 
 
 A. mill s. 
 
 
 Arsenic 
 
 ... As 
 
 Potash Sul. of Alumine . 
 
 .. KA1SO 
 
 Tellurium 
 
 Te 
 
 Ammonia ditto 
 
 AmAlSO 
 
 
 
 Soda ditto 
 
 .. NA1SO 
 
 35. 
 
 
 Potash Sulphate of Iron 
 
 KFeSO Dark Euby Silver 
 
 
 Ammonia ditto 
 
 AmFeSO Light do> do 
 
 
 Ditto Manganese 
 
 AmMnSO 
 
 
 
 Potash Sul. of Chromium 
 
 KCrSO 36. 
 
 
 Ammonia ditto 
 
 AmCrSO Arseniate of Lead 
 
 .. PbAsO 
 
 Potash Silicate of Alumine KAlSiO 
 
 Phosphate ditto 
 
 PbPO 
 
 32. 
 
 Apatite ... 
 
 .. CaPO 
 
 Rock Salt 
 
 V: : NCI 
 
 
 
 
 
 37. 
 
 
 Chloride of Silver 
 
 AgCl 
 
 
 
 Fluoride of Sodium 
 
 NF 
 
 Arseniate of Potash 
 
 .. KAsO 
 
 
 
 Phosphate ditto 
 
 KPO 
 
 33. 
 
 
 Arseniate of Ammonia 
 
 .. AmAsO 
 
 Double Chlorides. 
 
 Phosphate ditto 
 
 AmPO 
 
 Ammonia Chloride of Antimony, 
 
 
 AmSbCl 38. 
 
 
 Nickel 
 
 AmNiCl i Arseniate of Soda 
 
 NAsO 
 
 Cobalt 
 
 AmCoCl ; Phosnhate of ditto 
 
 NPO 
 
702 
 
 ISOMORPHOUS GROUPS. 
 
 39. 
 
 Biphospbate of Soda 
 Biarseniate of ditto ... 
 
 40. 
 Biphosphate of Ammonia 
 
 Biarseniate 
 
 ditto ... 
 
 41. 
 
 Biphosphate of Soda 
 Biarseniate ditto 
 
 NA 2 O 
 
 NAs 2 
 
 AmPO 
 AmAs 2 O 
 
 N 2 P 2 O 
 
 N 2 As 2 O 
 
 42. 
 
 Vivianite 
 Cobalt Bloom 
 
 43. 
 
 Molybdate of Lead 
 Tungstate ditto 
 
 Lime 
 
 44. 
 Spinelle ... ... MA1 2 4 
 
 Pleonaste ... ... MFeAl 2 O 5 
 
 Gahnite... ... ZnMFeAPO 6 
 
 Chromite of Iron . . . MFe 3 Cr 2 O 8 
 Franklinite ZnFe 3 Mn 2 8 
 
 Magnetic Iron Oxide Fe 3 4 
 
 Titanic Iron Oxide ... Fe 3 TiO 6 
 
 Abich (grandson of Klaproth) 
 states that these are octahedral, and 
 can be artificially formed by the 
 moist way. 
 
 45. 
 
 Garnets. 
 
 Grossular A 2 Si 2 Ca 3 O lrt 
 
 Almandine ... ... A 2 Si 2 Pe 3 10 
 
 Melanite ... Fe 2 Si 2 Ca :! O 10 
 
 Magnesian Garnet ... A 2 Si 2 Mn 3 10 
 
 46. 
 
 Specular Iron Oxide ... Fe 2 O <-! 
 
 Titanic Iron Oxide ... FeTiO 3 
 
 Corundum ... ... A 2 O 3 
 
 Peroxide of Manganese . . . Mn 2 3 
 
 Oxide of Tin 
 Rutile 
 
 47. 
 
 48. 
 
 SnO'< 
 TiO 2 
 
 Calc Spar ... ... CuCO 3 
 
 Bitter Spar ... ... CaC-MO 6 
 
 Carbonate of Magnesia and Iron, 
 
 MFeCO 4 
 
 Iron ... FeCO 3 
 
 Manganese Spar ... MriCO 3 
 
 Zinc ditto... ... ZnCO 3 
 
 Magnesia ditto ... MCO 3 
 
 49. 
 
 Arragonite 
 Witherite ... 
 Strontianite 
 Carbonate of Lead 
 
 50. 
 Acetate of Lead ... 
 
 Barytes ... 
 
 Olivine.., 
 Hyalosiderite 
 Crystals in Slags 
 
 51. 
 
 Pyroxene 
 
 Bisilicate of Manganese 
 
 CaCO 3 
 BaCO 3 
 SrCO 3 
 PbCO 3 
 
 ... P1HC0 3 
 
 BaHCO 3 
 
 ... M-'SiO 4 
 
 M 3 Fe :! SiO 5 
 
 . Fe :! SiO 4 
 
 52. 
 
 Tremolite 
 Anthophyllite 
 
 Mn 3 Si' 2 O 4 
 
 CaM'SrO* 
 FeM'SPO 8 
 
 DIMORPHOUS (Two Forms). 
 
 1. Elementary 
 Sulphur 
 Carbon 
 
 2. Two Elements 
 Bisulphuret of Iron 
 
 3. Three Elements 
 Carbonate of Lime 
 
 -Lead 
 Biphosphate of Soda 
 
4. Four Elements 
 Garnet, or 
 Idocrase 
 
 ISOMERIC SUBSTANCES. 703 
 
 5. 
 
 Sulphate of Nickel 
 
 Magnesia 
 Zinc 
 
 Seleniate ditto 
 
 The Groups numbered 19, 31, 32, 33, 44, 45, supply 
 octahedral crystals; 25, 26, 37, 43, 47, 49, square prismatic; 
 34, 35, 36, 46, 48, Rhombohedral ; 20, 21, 23, 24, 30, 38, 
 prismatic; 22, 27, 28, 29, 39, 40, 41, 42, 50, 51, 52, oblique 
 prismatic; and some varieties are doubly oblique prismatic. 
 The Isomorphism of the several groups of Elements, except; 
 the four which commence group 1, is assumed from that of their 
 'Compounds with the like number of atoms of oxygen. And the 
 links which reciprocally connect groups, 1, 4, 8, 9, render very 
 probable the isomorphism of these and all other Elements. 
 
 ISOMERIC SUBSTANCES. 
 
 These have the same Component Elements with like propor- 
 tions, and the same atomic weight : 
 
 1. The Phosphoric and Paraphosphoric Acids and their salts. 
 
 2. The Tartaric and Paratartaric (Racemic) Acids. 
 
 3. The Peroxide of Tin in the two states. 
 
 4. Silicic Acid and Silicates, native and incandesced. 
 
 5. Antimonites and Antimoniates, also after incandescence. 
 
 6. Tungstic Acid and Oxide in their two states. 
 
 7. Telluric Acid and Oxide in their two states. 
 
 8. Cyanuric Acids, soluble HCO [*CZHO a ], and insoluble HCO [*CZ0 2 ]. 
 
 9. The Cyanic and Fulminic Acids, HCO [* CZO] and HCO [* ZCHO]. 
 
 10. Oil of Wine and Faraday's light liquid Carbo-hydrogen, H 4 C 4 . 
 
 11. The Pyrotartaric and Pyroparatartic acids. 
 
 12. The Phosphate of Copper in both states. 
 
 13. The Bisulphuret of Mercury in both states. 
 
 14. The Phosphoretted Hydrogen in both states that which inflames 
 spontaneously in air, and that entirely indifferent to it. 
 
 15. The Iodide of Mercury in the two states. 
 
 16. The Chloride of Lithium in the two states. 
 
 17. The Mellate of Ammonia in the two states. 
 
704 METAMERIC AND POLYMERIC SUBSTANCES. 
 
 METAMERIC SUBSTANCES. 
 
 These have the same elements in precisely like proportions , 
 yet they compose substances completely different in their qualities. 
 
 .. f Cy anuric Acid .................. HCO ) Two atoms of the former 
 
 ' \Hydrous Cyanic Acid ......... HC / = three of the latter. 
 
 2 f Naphthaline ...... H 2 C 5 at 4-528 density of vapour I .-. 3 vols. of naphth. 
 
 " I Paranaphthaline H 2 C 5 at 6-741 ditto j = 2 do. paranaphth. 
 
 . fAsparagm ........... H 12 Z 3 C t5 O 4 
 
 ' \Aspartate of Ammonia. 
 5 fUrea .................................... - ..................... 
 
 '' (Cyanate of Ammonia with one atom of water../ H 4 Z 2 C 2 O 2 
 
 POLYMERIC SUBSTANCES. 
 
 These have the component elements in the like ratio, but not 
 the precisely same number. 
 
 1. Paraffin H 2 C 2 Olefiant gas H 2 C 2 Trito-carbo-hydrogen (?) H ri C" 
 Oil of Wine H 4 C 4 Faraday's Carbo-hydrogen H 4 C 4 . 
 
 2. Oils of Lemon and of Turpentine, and Camphogene H^C 10 Dumas. 
 
 3. Cyanogen, and the black residium from incandesced Cyanide of Mercury.. 
 
 4. Arabine and Cerasine H 5 C 6 5 Guerin. 
 
 5. Phosphoric and Paraphosphoric and Metaphosphoric Acids. 
 
 6. Cane Sugar, Diabetes sugar, Lignin. 
 
 7. Sugar of Milk, Manna, Gum Arabic. 
 
 Dumas entertains the opinion, that those Metals w T hich have 
 like atomic weights, similarity of forms, localities, chemical 
 properties, or other simple relation to each other, are in fact 
 isomeric or polymeric modifications of the same elements ; thus 
 
 Atoms. Atoms. Atoms. 
 
 Cobalt 368-99 I Platinum 1233-36 
 
 Nickel... ....369-67 Iridium 1233-36 
 
 Molybdenum 598-5 
 
 ^ Tungsten 596'5 
 
 Doubtless many others will present themselves to the in- 
 quirer ; and their comparison and close investigation may at 
 length suggest trains of research, productive of interesting and 
 
 i mYwrf.a rf, v<*onlt.c 
 
 important results. 
 
INDEX. 
 
 A. 
 
 Accum, 272 
 
 Acetate of Barytes, 109 
 
 Lead, 19, 109 
 
 Silver, 79 
 
 Achard's Pyrometer, 175 
 
 Acidity, 196 
 
 Acids, 53, 108, 120, 124, 130, 134, 
 
 195, 197, 201 
 Acid, Acetic, 66 
 
 Arsenic, 108, 120 
 
 Arsenious, 75, 108 
 
 -Boracic, 19,66, 104, 108, 120, 
 
 123, 202 
 Bromic, 108, 121 
 
 Carbazotic, 109 
 
 Carbonic, 108, 420, 124 
 
 Chloric, 108 
 
 Chromic, 108, 144 
 Citric, 19 
 
 Fluoric, 104 
 
 lodic, 108 
 
 Muriatic, 18, 67, 104, 109, 207 
 
 -Nitric, 18, 68, 104, 108, 109, 
 121, 209 
 
 - Nitrous, 53, 108 
 
 - Oxalic, 19, 68, 109 
 
 - Phosphoric, 103, 108, 1212 
 
 3 
 
 Silicic, 108, 109 
 
 Sulphuric, 18, 70, 10389, 
 
 120, 211 
 
 Sulphurous, 108 
 Tartaric, 19, 70, 109 
 
 Aciduline Bases, 199 
 
 Adams, 412, 417 
 
 Adepts 
 
 Affinity, 36, 43 
 
 Air, for fuel, and furnaces, 168, 178 
 
 Albertus Magnus, 359 
 
 Alcarazas, 459 % ' 
 
 Alchemists, 4, 5, 6, 40, 2835 
 
 Alcohol, 18, 52; 109 
 
 Alkalies, properties, 19589,201, 
 219, 426 
 - to detect, 146 
 
 Alkalinity, 197 
 
 Alkaline Bases, 199 
 Glazes, 4712 
 
 Alumine, 19, 489, 83, 96, 108, 118, 
 1237, 1413, 232 
 
 Aluminium, 17, 232 
 
 American Vases, 372 6 
 
 Ammonia, 27, 19, 56, 70, 94, 108, 
 119, 198 
 
 Benzoate, 72 
 
 Carbonate, 72, 109 
 
 Ferrocyanate, 73 
 
 Hydrosulphuret, 109 
 
 Muriate, 73, 109 
 
 Oxalate, 19, 74 
 : Phosphate, 164 
 
 Succinate, 109 
 
 Ammoniacal Sulphate of Copper. 74 
 Amulets, 397 
 
 Analysis, 8, 9, 17, 21, 48, 63, 107 
 Differences of, 55 
 - Frit, 482 
 General, 113 
 
706 
 
 INDEX. 
 
 Analysis, Glaze, 483 
 
 Particular, 141 
 
 Antimony, 27, 49, 108, 117. 124, 
 
 126, 180, 305 
 Antique Glass, 519 
 Apparatus, 17 
 Aqua Fortis, 210 
 
 - Regia, 335, 533 
 Arfwerdson, 268 
 
 Arsenic, 27, 102, 108, 124, 308 : 488 
 Assaying, 86, 104 
 Astbury, 247, 416 7 
 Atmosphere, 164 
 Atoms, 28, 30, 36 
 Attraction, 36, 43, 159 
 Attilianus, 385 
 Azote, 27 
 
 B. 
 
 Baddeley, 456 
 Baking, 171 
 Balance, 107 
 Barilla, 221 
 Barium, 19, 27, 202 
 Barytes, 489, 95, 108, 3 39, 123 
 58,142, 262,417, 491 
 
 Acetate, 19, 76, 109 
 
 Borate,,49, 204 
 
 Carbonate, 2685 
 
 Muriate, 76, 109 
 
 Nitrate, 19, 1G9 
 
 - Sulphate, 264 
 
 Water, 76 
 
 Basaltes, 417 
 
 Bases, 85, 108, 318 f. 12256, 
 132 
 
 Alkaline, 199 
 
 Yellow, 543 
 
 Baudissero Clay, 257 
 Beads, Pyrometrica). 170 3 
 
 Sivewright's, 173 
 
 Beccher, 3, 9 
 BecquereVs Analysis, 288 
 
 Belzoni, 376 
 Berard, 357 
 Berchiai's, 202 
 Bergman, 9, 15, 16, 37, 343 
 Berlin Porcelain, 4078 
 Berthollet, 9, 367 
 Berzelius, 9, 515, 138, 150 
 Billingsley, 429 
 Binoxalate of Potash, 109 
 Bird Daniel, 416 
 Bismuth, 27, 53, 99, 1085 
 Bistre, 538 
 Black, Dr., 325 
 
 410, 527, 546 
 
 Egyptian, 416 
 
 Flux, 74, 546 
 
 Wad, 344 
 
 Blende, 533 
 
 Blow-pipe, 18, 66, 859, 91 
 
 Blue, 527, 539 
 
 Cobalt, 379 ' 
 
 - Iron, 379 
 
 Green, 545 
 
 Matt, 540 
 BODIES, 10, 256, 48 
 
 Earthenware, 444, 4645 
 
 Black, 412, 463 
 
 - Blue printed, 465 
 
 Cane, 458, 463 
 
 Chemical Utensils, 462 
 
 Drab, 458, 462 
 
 Dry, 458 
 
 Egyptian, 412 
 
 Figures, Jasper, 466 
 
 Fawn, 462 
 
 Ironstone, 458 
 
 Jasper, 4589, 466 
 
 Mocha, 466 
 
 Moulds, Saucer, 466 
 
 Mortar, 462 
 
 Non-metallic, 109 
 
 Pearl, 4589, 462 
 Stone, 446, 458, 462 
 
INDEX. 
 
 707 
 
 BODIES, Porcelain, fritted, 4516 
 
 - Berlin, 4078, 446 
 
 - Bone, 417, 430 
 
 - Bow, 417 
 
 Champion's, 422 
 Dresden, 447 
 
 Nankin, 448 
 
 Nungarrow, 429 
 
 Raw, 4528 
 
 Red, 463 
 
 Sevres, 443 
 
 Bone Earth, 256, 455 
 Booth, 4147 
 
 Boracic Acid, see Acid, Boracic 
 Berates, 124 
 Borate of Alumine, 204 
 Barytes, 49, 204 
 
 Lime, 204 
 
 Magnesia, 204 
 
 Potash, 204 
 
 Silica, 204 
 
 Soda, 19, 80, 93, 2024 
 
 calcined, 80, 205 
 
 Glass, 80, 205 
 
 Boron, 27, 202 
 
 Boyle, 15, 342 
 
 Bradwell Ware, 410 
 
 Brande, 49, 364 
 
 Bricks, 371 
 
 Bromic Acid, see Acid, Bromic 
 
 Bromine, 27, 1049, 138 
 
 Bronze, 548 
 
 Brookes, 86, 417 
 
 Brown, 31, 338, 527, 537 
 
 - Red, 5378 
 Bwholz, 259, 321 
 Burslem, 396 
 Butter Pot, 414 
 Buxaros, 459 
 
 c. 
 
 Cadmium, 27, 98, 108, 117, 127 
 Cadmus, 359 
 
 Calcination, 23 
 Calcium, 27 
 Calcs, 23 
 Cane Ware, 463 
 Capacity for Heat, 159 
 Carbon, 27, 32, 162 
 Carbonate of Ammonia, 19 
 
 - Barytes, 19 
 " Magnesia, 19, 197 
 
 : Potash, 19, 109, 217 
 
 Soda, 19, 221 
 
 Cardan, 387 
 
 Carmine, 509 
 
 Cassius' Purple, 27 
 
 Castella Monte, 259 
 
 Castel Franco, 397 
 
 Castello Nuovo, 295 
 
 Cavendish, 15 
 
 Celeste, 545 
 
 Celsius' Thermometer, 177 
 
 Cementation, 23 
 
 Centigrade Thermometer, 177 
 
 Cerium, 27, 108, 128 
 
 Ceruse, 338 
 
 Chalk, 53 
 
 Body, 416 
 Champion, 422, 43 
 Chaptal, 37, 204 
 Characteristics of Metals, 290 
 Charcoal, 92, 162 
 Charpoy, 377 
 Chatter ley, 416 
 Chelsea Porcelain, 436 
 Chemical Separations, 227 
 Chert, 277 
 Chesterton, 388 
 Chesnut, 601 
 China Stone, 270 
 
 - Ware, 372, 436 
 Chlorides, 19, 109, 121, 142 
 Chlorine, 27, 1049, 138 
 Chromate of Potash, 19, 109 
 Chocolate, 537 
 
 z 2 
 
708 
 
 INDEX. 
 
 Chrome, 48, 83, 143, 312 
 
 Green, 108, 144, 311, 544 
 
 Yellow, 542 
 
 Chromium, 27, 1028, 309 
 Clarke, 86 
 
 Clay, 2345, 259, 273, 417, 441 
 Clement, 178 
 Clowes, 431 
 Coal, 179 to 192 
 
 Cobalt, 27, 76, 97, 108, 118, 122, 128, 
 142, 314 
 
 Arseniate, 321 
 
 - Blue, 379 
 
 - Hydrate, 319 
 
 Nitrate, 76, 109 
 Sulphate, 317 
 
 Coke, 164, 189 
 
 Colcothar, 335 
 
 Colours, 10, 51720, 527 
 
 Combinative Potency, 9, 21, 358, 
 
 406, 5247, 1616, 292 
 Composition, 51 
 Compounds, 21, 36, 114 
 
 Soluble, 115, 122, 124, 
 
 132 
 
 - Insoluble, 125, 137 
 Contraction, 1725 
 Cookworthy, 414 7 
 Copper, 19, 27, 66, 747, 83, 99. 
 
 1089, 115, 127, 142, 324 
 Crazing, 4723 
 Cream Colour, 444 
 Crouch Ware, 67 
 Crucibles, 524 
 
 D. 
 
 Dalt&n, Dr., 3, 8, 9, 16, 37, 51, 364 
 
 Daniel, 417 
 
 Daniell's Pyrometer, 174 
 
 Davenport, 196 
 
 Davy, 3, 5, 8, 9, 156, 337, 67, 
 
 148, 196, 202, 230 
 De Botcher, 5, 401 
 
 Decomposition, 21, 161 
 
 De Entrccolles, 399 
 
 Definite Proportions, 37 
 
 Delaval, 379 
 
 Delft Ware, 373, 393, 444 
 
 Delisle's Thermometer, 177 
 
 Delia Eobia, 397 
 
 Demaratus, 386 
 
 Demi-Johns, 459 
 
 Density, 28 
 
 Derby Porcelain, 436 
 
 Dilwyn's do. 261 
 
 Dipped Ware, 346, 416 
 
 Dips, 490 
 
 Dipper's Cholic, 443 
 
 Dobereiner, 30 
 
 Drab Ware, 462 
 
 Dresden Porcelain, 5, 40257, 
 
 446 
 
 Dumas, 16, 51 
 Dutch Lead, 543 
 
 B. 
 
 Earths, 33, 201, 229 
 
 Earthen Boats, 377 
 
 Chariot, 389 
 
 - Horse, 389 
 
 - Wares, 4647 
 Edwards, 417 
 Egyptian Black, 463 
 Ehrman, 426 
 
 Electricity, 26, 28, 31, 159, 166 
 Elements, 3, 21, 25 67 
 Elers, 409, 417 
 Emerald Green, 527, 544 
 Enamel Colours, 379, 417, 521, 537 
 Equivalence, 22, 30 
 Etruria, 385, 563 
 
 F. 
 
 Fahrenheit's Thermometer, 177 
 Pawn Body, 462 
 Faraday, Dr., 8, 90, 364 
 
INDEX. 
 
 709 
 
 Fayance, 386, 397 
 Felspar, 236, 2667, 437 
 Ferrocyanate of Ammonia, 73 
 
 Potash, 19, 78, 109 
 
 Figures for Jasper, 409 
 Filtration, 22, 224 
 Finiguera, 541 
 Flame, 32 
 Flaxman, 562 
 Flint, 236, 245, 417 
 
 - Ware, 416, 444 
 Flowers, 24 
 
 of Antimony, 306 
 
 Zinc, 361 
 
 Fluidity, 245, 445 
 Fluoric Acid, 104 
 Fluorine, 27, 1049, 1204 
 Flux, 93, 522, 525, 549 
 Forchammer, 346 
 Fossil Alkali, 219 
 Fourcroy, 9, 37 
 Fox, Robert, Ware, 281 
 Frederic II. 
 Fritting, 470, 482 
 Fulminating Gold, 322 
 Furnace, 110, 260 
 Fusion, 21 
 
 G. 
 
 Gahn, 77, 254, 343 
 
 Galena, 265, 339, 417 
 
 Galvanism, 6, 281 
 
 Gardner, 417 
 
 Gay Lussac, 9, 41, 200 
 
 German Porcelain , 450 
 
 Geysers, Iceland, 237 
 
 Gilding, 417 
 
 Gioannetti, 259 
 
 Glass, 493516 
 
 Glaze, Alkaline, 4712 
 
 Glazes, 10, 221, 441, 469, 478, 4818 
 
 Coloured, 490 
 Nankin, 448 
 
 Glazes, Porcelain, 475 
 
 Salt, 412 
 
 Sevres, 449 
 
 Glucinum, 27 
 Glucina, 96, 108, 118, 142 
 Goettling, 354 
 Gmelin, 51, 519 
 
 Gold, 27, 77, 108, 116, 126, 320, 328, 
 3308 
 
 Burnishing, 549 
 
 Lustres, 551 
 Granite, 207, 417 
 Granulation, 4, 23 
 Gravy-Dish, 414 
 Greens, 3416, 5445, 527 
 Grounds, 523, 538 
 Guillot, 254 
 Gurney, 86, 105 
 Guyton, 259, 441, 4769 
 Gypsum, 259, 417 
 
 H. 
 
 Hancock, 417, 484 
 Handley, 485 
 Haussman, 390 
 Heat, 32, 157, 1678 
 Henry, 49, 315, 364 
 Hermstadt, 321 
 Hennys, 417 
 Herschel, 8 
 Higgins, 37 
 
 Hodson's Patent Soda, 222 
 Hydriodate of Zinc, 81 
 Hydrogen, 27, 32, 81, 109 
 
 I. 
 
 Incompatible Colours, 557 
 Compounds, 48 
 
 Iodide of Potassium, 109 
 
 Iodine, 27, 1049, 138 
 
 Iridium, 27, 100 
 
 Iron, 19, 27, 56, 66, 68, 77, 83, 98, 
 1089, 110, 1178, 1227, 
 141_3_4_5 ) 3345, 379 
 
710 
 
 INDEX. 
 
 Isomeric Substances, 703 
 Isomerism, 698 
 Isomorphism, 698 
 Isomorphous Groups, 698 702 
 
 J. 
 
 Jars, secure, 18, 20 
 Jasper Body, 435, 462 
 Jones's G. Glaze, 486 
 
 K. 
 
 Kaolin, 399, 4057, 417, 437 
 Kelp, 412 
 Kirwan, 37 
 Klaproth, 279, 519 
 Kuhlman, 540 
 
 L. 
 
 Labels, 20 
 
 Laboratory, 9, 17, 20 
 
 Lakin, 430 
 
 Lamp, 18,. 88, 110 
 
 Laquier, 323 
 
 Lavoisier, 15 
 
 Lead, 27, 49, 77, 98, 108, 117, 122 
 
 45, 336, 340, 417 
 Leaf Silver, 77 
 Leeds, 265 
 Leibnitz, 401 
 Light, 32, 167 
 Light, Red, 537 
 Lime, 489, 56, 77, 83, 95, 108, 
 
 12358, 142, 25346, 
 
 479 
 
 Limoges, 405 
 Litharge, 399, 417 ' 
 Lithia, 489, 94, 108, 119, 198, 226 
 Litmus, 19 
 Littler, 417, 436 
 Lowitz, 110, 147, 269 
 Lucock, 562 
 Lustre, 417, 551 
 Lynn Sand, 221 
 
 M. 
 
 Machin, 417 
 
 Magnesium, 27, 344 
 
 Magnesia, 489, 83, 95, 108, 123 
 
 8, 14123, 258 
 Majolica, 397 
 Manganese, 27, 48, 83, 97, 118, 122 
 
 _8, 143 -45, 417 
 Manipulations, 7, 11, 63, 110 
 Marie, 417 
 Massicot, 337 
 Matt Blue, 297 
 Metameric Substances, 704 
 Mercury, 27, 58, 778, 100, 1089, 
 
 116, 1247 
 Metals, 6, 21, 231, 278 
 
 Combinative Potencies, 292 
 
 Microsmic Salts, 94 
 Mineral Alkali, 219 
 
 Green, 545 
 Minium, 338 
 Mitchell, John, 170 
 Mocha Ware, 346, 410 
 Modelling, 381 
 Molybdenum, 102 
 Montgolfier, 178 
 Mortar Body, 84, 462 
 Morveau, 36 
 Motion, 36 
 Moulds, 256 
 Mulberry Ware, 538 
 Muncke, 31 
 Muriate of Platinum, 109 
 
 Ammonia, 73, 109 
 Muriatic Acid, see Acid, Muriatic 
 
 N. 
 
 Nankin Porcelain, 259, 4468 
 Napoleon, 5 
 Nasturtium, 543 
 Natron, 487 
 
 Newcastle-under-Lyme, 388 
 New Hall (Shelton) Porcelain, 43 
 
INDEX. 
 
 711 
 
 Nickel, 27, 66, 83, 98, 108, 118, 122 
 
 8, 1423 
 Nitrate of Mercury, 109 
 
 Potash, 19, 52 
 
 Silver, 19, 109 
 
 Nitrogen, 56 
 
 Nitron, or Nitrum, 219 
 
 Nitrous Acid, see Acid, Nitrous 
 
 Nola, 385 
 
 Nuneaton Manganese, 345 
 
 Nungarrow, 429 
 
 o. 
 
 Ochre, 417 
 Oerschal, 332 
 Oil of Vitriol, 211 
 Olive Green, 545 
 Orange Colour, 527, 543 
 Ores of Metals, 281 
 Origin of Pottery, 362, 415 
 Orpiment, 308 
 Osmium, 27, 100 
 Over-flinting, 434 
 Oxalate of Ammonia, 19, 74 
 Oxalic Acid, see Acid, Oxalic 
 Oxides of Metals, 23, 53 
 Oxygen, 27, 32, 56 
 
 P. 
 
 Painting, 417 
 
 Palladium, 27 
 
 Pallas, 334 
 
 Palmer, 412, 417 
 
 Palissy, 398 
 
 Paris White, 254 
 
 Parkes, 395 
 
 Patent Iron-stone China, 446 
 
 Pearl Body, 462 
 
 Petalite, 268 
 
 Petuntse, 417, 437, 399, 4057 
 
 Phoenicians, 381 
 
 Pink, 527, 537 
 
 Plaster of Paris, 256 
 
 Platinum, 27, 78, 92, 1008, 348 
 
 Phillips, Sir R., 33 
 Phosphorus, 27 
 
 Phosphate of Soda, 19,49, 80, 109, 223 
 Polymerism, 704 
 Polymeric Substances, 704 
 Poisson, 28 
 
 Porcelain, 6, 12, 259, 399, 429, 430 
 8, 441, 450 
 
 Hard Fritted, 445, 451 
 
 Soft ditto, 446, 455 
 
 Hard Raw, 452 
 
 Soft ditto, 458, 403 
 
 De Botcher's, 403 
 Chelsea, 436 
 
 Reaumur's, 177, 406 
 
 Sevres, 446 
 
 Spanish, 260 
 Vienna, 446, 450 
 
 Swansea, 260 
 
 Glazes, 475 
 
 Potash, 18, 24, 489, 556, 1089, 
 
 119, 215 
 Pottery, Roman, 390 
 
 - 6, 9, 12, 367, 417, 441 
 Potter's Wheel, 380 
 Potts, 417 
 
 Precipitant, General, 82 
 Preparation of Tests, 19, 20 
 Priestley, 38, 9 
 Printing, 194, 417, 541 
 Printer's Oil, 550 
 
 Stoves, 194 
 
 Proust, 260, 284 
 
 Psalmanazar, 407 
 
 Pure White, 547 
 
 Purple, 333, 357, 5273132 
 
 Pyrites, 230 
 
 Pyrometer, 1609, 17345 
 
 Q. 
 
 Quantities, Relative, 150 
 Quartz, 237 
 Queen's Ware, 416 
 
712 
 
 INDEX. 
 
 a 
 
 Rats-stone, 125 
 Raymond Lully, 332 
 Re-agents, 8, 20, 656, 1079 
 Realgar, 308 
 Reaumur, 177, 405 
 Recipes, 12, 399 
 Red Colours, 459, 527, 536 
 Lead, 338 
 
 Porcelain, 463 
 
 Rhodium, 27, 100 
 Richter, 37 
 Rifting, 434 
 Riley's Glaze, 416 
 Rivers, 431 
 Roasting, 92 
 Robison, 17 
 Rock Crystal, 237 
 Rose, 55 
 
 Rose Colour, 529, 537 
 Ryan, 417, 437 
 
 S. 
 
 Saffron of Mars, 335 
 Salts, 21, 417 
 
 Glaze, 447 
 
 Sans, 417 
 Saussure, 426 
 Scheele, 9, 254, 343 
 
 Green, 545 
 
 Schroder, 147 
 
 Schurer, 519 .^ 
 
 Selenium, 27, 103 
 
 Sevres Porcelain, 408, 449 ' > 
 
 Shaw, Ralph, 169, 417 
 
 Sherrard, 407 
 
 Sidon, 381, 563 
 
 Silver, 27, 79, 80, 99, 108, 116, 122 
 
 for Burnishing, 548 
 Silicium, 27, 239 
 
 Silica, 489, 67, 96, 109, 1413 
 678, 23679 
 
 Sivewright's Beads, 173 
 Smears, 491 
 Smith, 417 
 Sodium, 27, 217, 220 
 Soda, 19, 48, 49, 55, 817, 94, 108, 
 119, 188, 219, 223, 417 
 
 Hodson's Patent, 222 
 
 Solids, 24 
 
 Solution, 21, 42, 109 
 
 Spetre, 359 
 
 Spode, 422 
 
 Stahl, 5, 9 
 
 Statues, 383 
 
 Steatite, 260 
 
 St. Cloud, 395, 405 
 
 Steam Heat, 193 
 
 Steel, 68 
 
 St. Fond, 464 
 
 Stoke-upon-Trent, 395 
 
 Stone- Ware, 416, 4414, 462 
 
 Stromeyer, 206 
 
 Strontia, 27, 94, 108, 119, 1235 
 
 8, 142, 262 
 
 Sulphur, 27, 109, 124 
 Sulphuric Acid, see Acid, Sulphuric 
 Sun Pan, 442 
 Sureda, 260 
 Symbols, 26 
 Synthesis, 9, 21, 48, 64, 339 
 
 T. 
 
 Tables, 572 
 
 .Jantalum, 27, 103, 143 
 Taps, 86 
 
 Tellurium, 27, 102 
 Temperature, 51, 157 
 Terra Gotta, 397 
 'Tests, 18, 19, 20, 66 
 Thenard, 202 
 Thermometer, 177 
 Thomson, 9, 37, 51, 148 
 Thorina, 27, 96, 108 
 Tilley, 86 
 
INDEX. 
 
 713 
 
 Tin, 27, 66, 100, 108, 117, 1246 
 Ashes, 357 
 
 Chloride, 109, 357 
 - Oxide, 3578, 478 
 
 Solutions, 529 
 Tincal, 80, 204, 487 
 Titanium, 27, 100, 143 
 Toft, 86, 417 
 Tortoiseshell Ware, 538 
 Transmutation, 5, 289 
 Tungsten, 27, 101 
 Turner, 51, 343, 422 
 Turpentine, 24 
 Twyford, 4167 
 Tyre, 380, 563 
 
 u. 
 
 Ultramarine, 540 
 Uranium, 27, 103 
 
 V. 
 
 Valentine, 5, 305 
 Vanadium, 27 
 Vasa murrhina, 386 
 Vases, 371 
 
 Vauquelin, 55, 260, 428 
 Venetians, 381, 411 
 Vienna Gresn, 521 
 
 Vineuf, 259 
 Vitrification, 286 
 
 w. 
 
 Warburton, 417 
 
 Washes, 491 
 
 Water, 24, 27, 39, 40, 65 
 
 - Pipes, 387 
 Wedgwood, 84, 170, 416 
 Wensscll, 37 
 Westnimb, 540 
 White Lead, 338, 417 
 
 - Ware, 416 
 Witherite, 265 
 Wollaston, 37, 350 
 Wood, 406 
 Worcester Porcelain, 436 
 
 Y. 
 
 Yates, 436 
 
 Yellow, 3357, 527, 5412 
 
 Yttrium, 27 
 
 Yttria, 96, 103 
 
 z. 
 
 Zinc, 27, 667, 81, 97, 1089, 118, 
 
 123, 142, 359 
 Zirconia, 27, 96, 108 
 
 FIMS. 
 
A CATALOGUE 
 
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3 
 
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 ANIMAL FATS AND OILS : Their Practical Production, Puri- 
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 VEGETABLE FATS AND OILS : Their Practical Preparation, 
 Purification and Employment for Various Purposes, their Properties, 
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 LUBRICATING OILS, FATS AND GREASES : Their Origin, 
 Preparation, Properties, Uses and Analyses. A Handbook for Oil 
 Manufacturers, Refiners and Merchants, and the Oil and Fat Industry 
 in General. By GEORGE H. HURST, F.C.S. Price 10s. 6d. ; Germany, 
 12 mkp. : France and Belgium, 13 frs. ; Colonies, 12s., post free. 
 
Contents. 
 
 Chapters I., Introductory. Oils and Fats, Fatty Oils and Fats, Hydrocarbon Oils, Uses 
 of Oils. II., Hydrocarbon Oils. Distillation, Simple Distillation, Destructive Distillation, 
 Products of Distillation, Hydrocarbons, Paraffins, Olefins, Naphthenes. III., Scotch Shale 
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6 
 
 THE MANUFACTURE OF VARNISHES, OIL REFINING 
 AND BOILING, AND KINDRED INDUSTRIES. Describing 
 the Manufacture of Spirit Varnishes and Oil Varnishes ; Raw Materials : 
 Resins, Solvents and Colouring Principles ; Drying Oils : their Pro- 
 perties, Applications and Preparation by both Hot and Cold Processes; 
 Manufacture, Employment and Testing of Different Varnishes. Trans- 
 lated from the French of ACH. LIVACHE. Greatly Extended and 
 Adapted to English Practice, with numerous Original Recipes. By 
 J. G. MclNTOSH, Lecturer on Oils, Colours and Varnishes. Price 
 12s. 6d. France and Belgium, 16 frs. ; Colonies, 14s., post free. 
 
 Contents. 
 
 I. Resins : Gum Resins, Oleo Resins and Balsams, Commercial Varieties, Source, Collection, 
 Characteristics, Chemical Properties, Physical Properties, Hardness, Adulterations, Appro- 
 priate Solvents, Special Treatment, Special Use. II. Solvents: Natural, Artificial, Manufac- 
 ture, Storage, Special Use. III. Colouring : Principles, (i) Vegetable, (2) Coal Tar, (3) Coloured 
 Resinates, (4) Coloured Oleates and Linoleates. Gum Running : Furnaces, Bridges, Flues, 
 Chimney Shafts, Melting Pots, Condensers, Boiling or Mixing Pans, Copper Vessels, Iron 
 Vessels "(Cast), Iron Vessels (Wrought), Iron Vessels (Silvered), Iron Vessels (Enamelled), 
 Steam Superheated Plant, Hot-air Plant. Spirit Varnish Manufacture : Cold Solution Plant, 
 Mechanical Agitators, Hot Solution Plant, Jacketted Pans, Mechanical Agitators, Clarification 
 and Filtration, Bleaching Plant, Storage Plant. Manufacture, Characteristics and Uses of the 
 Spirit Varnishes yielded by : Amber, Copal, Dammar, Shellac, Mastic, Sandarac, Rosin, Asphalt, 
 India Rubber, Gutta Percha, Collodion, Celluloid, Resinates, Oleates. Manufacture of Varnish 
 Stains. Manufacture of Lacquers. Manufacture of Spirit Enamels. Analysis of Spirit Var- 
 nishes. Physical and Chemical Constants of Resins. Table of Solubility of Resins in different 
 Menstrua. Systematic qualitative Analysis of Resins Hirschop's tables. Drying Oils : Oil Crush- 
 ing Plant, Oil Extraction Plant, Individual Oils, Special Treatment of Linseed Oil, Poppyseed 
 Oil. Walnut Oil, Hempseed Oil, Llamantia Oil, Japanese Wood Oil, Gurjun Balsam, Climatic 
 Influence on Seed and Oil. Oil Refining: Processes, Thenard's, Liebig's, Filtration, Storage, 
 Old Tanked Oil. Oil Boiling: Fire Boiling Plant, Steam Boiling Plant, Hot-air Plant, Air 
 Pumps, Mechanical Agitators, Vincent's Process, Hadfield's Patent, Storer's Patent, Walton's 
 Processes, Continental Processes, Pale Boiled Oil, Double Boiled Oil, Hartley and Blenkinsop's 
 Process. Driers: Manufacture, Special Individual Use of (i) Litharge, (2) Sugar of Lead, (3) 
 Red Lead, (4) Lead Borate, (5) Lead Linoleate, (6) Lead Resinate, (7) Black Oxide of Man- 
 ganese, (8) Manganese Acetate, (9) Manganese Borate, (10) Manganese Resinate, (n) Manganese 
 Linoleate, Mixed Resinates and Linoleates, Manganese and Lead, Zinc Sulphate, Terebine, 
 Liquid Driers. Solidified Boiled Oil. Manufacture of Linoleum. Manufacture of India 
 Rubber Substitutes. Printing Ink Manufacture. Lithographic Ink Manufacture. Manufacture 
 of Oil Varnishes. Running and Special Treatment of Amber, Copal, Kauri, Manilla. Addition 
 of Oil to Resin. Addition of Resin to Oil. Mixed Processes. Solution in Cold of previously 
 fused Resin. Dissolving Resins in Oil, etc., under pressure. Filtration. Clarification. 
 Storage. Ageing. Coachmakers' Varnishes and Japans. Oak Varnishes. Japanners' Stoving 
 Varnishes. Japanners' Gold Size. Brunswick Black. Various Oil Varnishes. Oil-Varnish 
 Stains. Varnishes for "Enamels". India Rubber Varnishes. Varnishes Analysis: Pro- 
 cesses, Matching. Faults in Varnishes : Cause, Prevention. Experiments and Exercises. 
 
 Press Opinions. 
 
 " There is no question that this is a useful book." Chemist and Druggist. 
 
 ' The different formulae which are quoted appear to be far more ' practical ' than such as are 
 usually to be found in text-books; and assuming that the original was published two or three 
 years ago, and was only slightly behindhand in its information, the present volume gives a fair 
 insight into the position of the varnish industry." The Ironmonger. 
 
 THE TESTING AND VALUATION OF RAW MATERIALS 
 USED IN PAINT AND COLOUR MANUFACTURE. By M. W. 
 
 JONES, F.C.S. A book for the laboratories of colour works. Price 5s. ; 
 Colonies and Continent, 6s., strictly net, post free. 
 
 Contents. 
 
 Aluminium Compounds. China Clay. Iron Compounds. Potassium Compounds. Sodium 
 Compounds. Ammonium Hydrate. Acids. Chromium Compounds. Tin Compounds. Copper 
 Compounds. Lead Compounds. Zinc Compounds. Manganese Compounds. Arsenic Com- 
 pounds. Antimony Compounds. Calcium Compounds. Barium Compounds. Cadmium 
 Compounds. Mercury Compounds. Ultramarine. Cobalt and Carbon Compounds. Oils. 
 Index. 
 
 Press Opinion. 
 
 " Though this excellent little work can appeal only to a limited class, the chemists in colour 
 works, yet it will appeal to them very strongly indeed, for it will put them on the track of short, 
 rapid, and yet approximately, accurate methods of testing the comparative value of competing 
 samples of raw material used in paint and colour manufacture." North British Daily Mail. 
 
THE CHEMISTRY OF ESSENTIAL OILS AND ARTIFI = 
 CIAL PERFUMES. By ERNEST J. PARRY, B.Sc. (Lond.), F.I.C., 
 F.C.S. Illustrated with 20 Engravings. 400 pp. Price 12s. 6d. ; 
 Abroad, 14s., strictly net, post free. 
 
 Contents. 
 
 Chapters I.. The General Properties of Essential Oils.- -II., Compounds occurring 
 in Essential Oils. Ill . The Preparation of Essential Oils. IV., The Analysis of 
 Essential Oils. V.. Systematic Study of the Essential Oils. VI., Terpeneless Oils. 
 VII . The Chemistry of Artificial Perfumes. Appendix : Table of Constants. 
 
 Press Opinions. 
 
 "At various times monographs have been printed by individual workers, but it may safely 
 be said that Mr. Parry is the first in these latter days to deal with the subject in an adequate 
 manner. His book is well conceived and well written. . . . He is known to have sound practical 
 experience in analytical methods, and he has apparently taken pains to make himself an fait 
 with the commercial aspects of the subject." Chemist and Druggist. 
 
 " We can heartily recommend this volume to all interested in the subject of essential oils 
 from the scientific or the commercial standpoint " British ami Colonial Druggist. 
 
 " There can be no doubt that the publication will take a high place in the list of scientific 
 text-books." London Argus. 
 
 " A most useful appendix is inserted, giving a table of constants for the more important 
 essential oils. . . . This, in itself, is of sufficient importance and use to warrant the publication 
 of the book, and. added to the very complete classification and consideration of the essential 
 oils which precedes it, the volume becomes of great value to all interested." Glasgow Herald. 
 " Mr. Parry has done good service in carefully collecting and marshalling the results of the 
 numerous researches published in various parts of the world." Pharmaceutical Journal. 
 
 COLOUR: A HANDBOOK OF THE THEORY OF COLOUR. 
 
 By GEORGE H. HURST, F.C.S. With 10 coloured Plates and 72 Illus- 
 trations. Price 7s. 6d. ; Abroad, 9s., post free. 
 
 Contents. 
 
 Chapters I.. Colour and its Production. II., Cause of Colour in Coloured Bodies. 
 III., Colour Phenomena and Theories. IV., The Physiology of Light. V., Contrast. 
 VI., Colour in Decoration and Design. VII., Measurement of Colour. 
 
 Press Opinions. 
 
 " This is a workmanlike technical manual, which explains the scientific theory of colour in 
 terms intelligible to everybody. ... It cannot but prove both interesting and instructive to all 
 classes of workers in colour." Scotsman. 
 
 " Mr. Hurst's Handbook on the Theory of Colour will be found extremely useful, not only to 
 the art student, but also to the craftsman, whose business it is to manipulate pigments and 
 dyes." Nottingham Daily Guardian. 
 
 " It is thoroughly practical, and gives in simple language the why and wherefore of the many 
 colour phenomena which perplex the dyer and the colourist." Dyer and Calico Printer. 
 
 " We have found the book very interesting, and can recommend it to all who wish to master 
 the different aspects of colour theory, with a view to a practical application of the knowledge so 
 gained." Chemist and Druggist. 
 
 " It will be found to be of direct service to the majority of dyers, calico printers and colour 
 mixers, to whom we confidently recommend it." Chemical Trade Journal. 
 
 " This useful little book possesses considerable merit, and will be of great utility to those for 
 whom it is primarily intended." Birmingham J'ost. 
 
 IRON = CORROSION, ANTI = FOULING AND ANTI = 
 CORROSIVE PAINTS. By Louis EDGAR ANDES. 275 pp., 
 sixty-two Illustrations. Translated from the German. Price 10s. (Sd. ; 
 Abroad, 12s., strictly net, post free. 
 
 Contents. 
 
 Ironrust and its Formation Protection from Rusting by Paint Grounding the Iron with 
 Linseed Oil, etc. Testing Paints Use of Tar for Painting on Iron Anti-corrosive Paints 
 Linseed Varnish Chinese Wood Oil Lead Pigments Iron Pigments Artificial Iron Oxides 
 Carbon Preparation of Anti-corrosive Paints Results of Examination of Several Anti- 
 corrosive Paints Paints for Ship's Bottoms Anti-fouling Compositions Various Anti-cor- 
 rosive and Ship's Paints Official Standard Specifications for Ironwork Paints Index. 
 
 Press Opinion. 
 
 " The book before us deals with the subject in a manner at once practical and scientific, and 
 is well worthy of the attention of all builders, architects and engineers." The Builder. 
 
THE LEATHER WORKER'S MANUAL. Being a Com- 
 pendium of Practical Recipes and Working Formula; for Curriers, 
 Bootmakers, Leather Dressers, Blacking Manufacturers, Saddlers, 
 Fancy Leather Workers, and all Persons engaged in the Manipulation 
 of Leather. By H. C. STANDAGE. Price 7s. 6d. ; Abroad, 9s., strictly 
 net, post free. 
 
 Contents. 
 
 Chapters I., Blackings, Polishes, Glosses, Dressings, Renovators, etc., for Boot and Shoe 
 Leather. II., Harness Blackings, Dressings, Greases, Compositions, Soaps, and Boot-top 
 Powders and Liquids, etc., etc. III., Leather Grinders' Sundries. IV., Currier's Seasonings, 
 Blacking Compounds, Dressings, Finishes, Glosses, etc. V., Dyes and Stains for Leather. 
 VI., Miscellaneous Information. VII., Chrome Tannage. Index. 
 
 Press Opinions. 
 
 "The book being absolutely unique, is likely to be of exceptional value to all whom it con- 
 cerns, as it meets a long-felt want." Birmingham Gazette. 
 
 " This is a valuable collection of practical receipts and working formulae for the use of those 
 engaged in the manipulation of leather. We have no hesitation in recommending it as one of 
 the best books of its kind, an opinion which will be endorsed by those to whom it appeals." 
 Liverpool Mercury. 
 
 GLUE AND GLUE TESTING. By SAMUEL RIDEAL, D.Sc. 
 Lond., F.I.C. Fourteen Engravings. Price 10s. 6d., strictly net ; United 
 States. 3 dols. ; Germany, 12 mks. ; France and Belgium, 13 frs., post free. 
 
 Contents. 
 
 Chapters I., Constitution and Properties: Definitions, Sources, Gelatine, Chondrin and 
 Allied Bodies, Physical and Chemical Properties, Classification, Grades and Commercial 
 Varieties. II., Raw Materials and Manufacture: Glue Stock, Lining, Extraction, 
 Washing and Clarifying, Filter Presses, Water Supply, Use of Alkalies, Action of Bacteria and 
 of Antiseptics, Various Processes, Cleansing, Forming, Drying, Crushing, etc., Secondary 
 Products. III., Uses of Glue: Selection and Preparation for Use, Carpentry, Veneering, 
 Paper Making, Book-binding, Printing Rollers, Hectographs, Match Manufacture, Sandpaper, 
 etc., Substitutes for other Materials, Artificial Leather and Caoutchouc. IV., Gelatine : 
 General Characters, Liquid Gelatine, Photographic Uses, Size, Tanno- Chrome, and Formo- 
 Gelatine, Artificial Silk, Cements, Pneumatic Tyres, Culinary, Meat Extracts, Isinglass, 
 Medicinal and other Uses, Bacteriology. V., Glue Testing; : Review of Processes, Chemical 
 Examination, Adulteration, Physical Tests, Valuation of Raw Materials. VII., Commercial 
 Aspects. 
 
 Press Opinion. 
 
 " This work is of the highest technical character, and gives not only a full and practical 
 account of the raw materials ani manufacture of glues, gelatines and similar substances, but 
 gives many hints and information on the use of such substances in veneering, carpentry and 
 many other purposes. Many tests are given for glue in different stages of the progress of its 
 manufacture, and the commercial value of a commodity so much in general use is exemplified 
 by statistics and figures. It is certainly a valuable treatise upon an article for which very little 
 literature in any form has previously been obtainable." Carpenter and Builder. 
 
 PURE AIR, OZONE AND WATER. A Practical Treatise 
 of their Utilisation and Value in Oil, Grease, Soap, Paint, Glue and 
 other Industries. By W. B. COWELL. Twelve Illustrations. Price 
 5s. ; Abroad, 6s., strictly net, post free. 
 Contents. 
 
 Chapters I., Atmospheric Air; Lifting of Liquids; Suction Process; Preparing Blown Oils; 
 Preparing Siccative Drying Oils. II., Compressed Air; Whitewash. III., Liquid Air; Retro- 
 cession. IV., Purification of Water; Water Hardness. V., Fleshings and Bones. VI., Ozon- 
 ised Air in the Bleaching and Deodorising of Fats, Glues, etc.; Bleaching Textile Fibres. 
 Appendix: Air and Gases; Pressure of Air at Various Temperatures; Fuel; Table of Com- 
 bustibles ; Saving of Fuel by Heating Feed Water ; Table of Solubilities of Scale Making 
 Minerals ; British Thermal ; Units Tables ; Volume of the Flow of Steam into the Atmosphere ; 
 Temperature of Steam. Index. 
 
 Books on Pottery, Glass, etc. 
 
 THE MANUAL OF PRACTICAL POTTING. Price 17s. 6d. ; 
 
 Colonies and Continent, 18s., post frj. . 
 
 Contents. 
 
 Introduction. The Rise and Progress of the Potter's Art. Chapters I., Bodies. China 
 and Porcelain Bodies, Parian Bodies, Semi-porcelain and Vitreous Bodies, Morter Bodies, 
 Earthenwares Granite and C.C, Bodies, Miscellaneous Bodies, Sagger and Crucible Clays, 
 
Coloured Bodies, Jasper Bodies, Coloured Bodies for Mosaic Painting, Encaustic Tile Bodies, 
 Body Stains, Coloured Dips. II., Glazes. China Glazes, Ironstone Glazes, Earthenware 
 Glazes Glazes without Lead, Miscellaneous Glazes, Coloured Glazes, Majolica Colours. III., 
 Gold and Cold Colours. Gold, Purple of Cassius, Marone and Ruby, Enamel Colour Bases, 
 Enamel Colour Fluxes, Enamel Colours, Mixed Enamel Colours, Antique and Vellum Enamel 
 Colours, Underglaze Colours, Underglaze Colour Fluxes, Mixed Underglaze Colours, Flow 
 Powders Oils and Varnishes. IV., Means and Methods. Reclamation of Waste Gold, The 
 Use of Cobalt, Notes on Enamel Colours, Liquid or Bright Gold. V., Classification and 
 Analysis. Classification of Clay Ware, Lord Playfair's Analysis of Clays, The Markets of the 
 World, Time and Scale of Firing, Weights of Potter's Material, Decorated Goods Count.- 
 VI., Comparative Loss of Weight of Clays. VII., Ground Felspar Calculations. VIII., The 
 Conversion of Slop Body Recipes into Dry Weight. IX., The Cost of Prepared Earthenware 
 Clay. X., Forms and Tables. Articles "of Apprenticeship. Manufacturer's Guide to Stock- 
 taking, Table of Relative Values of Potter's Materials, Hourly Wages Table, Workman's 
 Settling Table, Comparative Guide for Earthenware and China Manufacturers in the Use of 
 Slop Flint and Slop Stone, Foreign Terms applied to Earthenware and China Goods, Table 
 for the Conversion of Metrical Weights and Measures on the Continent of South America. 
 
 CERAMIC TECHNOLOGY : Being some Aspects of Technical 
 Science as Applied to Pottery Manufacture. Edited by CHARLES F. 
 BINNS. Price 12s. 6d. ; Colonies and Continent, 14s., post free. 
 Contents. 
 
 Preface. Introduction. Chapters I., The Chemistry of Pottery II., Analysis and Syn- 
 thesis. III., Clays and their Components. IV.. The Biscuit Oven. V., Pyrometry. VI., 
 Glazes and their Composition. VII., Colours and Colour-making Index. 
 
 COLOURING AND DECORATION OF CERAMIC WARE. 
 
 By ALEX. BRONGNIART. With Notes and Additions by ALPHONSE 
 SALVETAT. Translated from the French. 200 pages. Price 7s. ed., 
 strictly net, post free. 
 
 HOW TO ANALYSE CLAY. Practical Methods for Practical 
 Men. By HOLDEN M. ASHBY, Professor of Organic Chemistry. Price 
 2s. 6d., strictly net, post free. 
 
 THE ART OF RIVETING GLA55, CHINA AND EARTHEN- 
 WARE. ByJ. HONVARTH. Second Edition. Price Is. ; by post. Is. 2d. 
 
 PAINTING ON GLASS AND PORCELAIN AND ENAMEL 
 PAINTING. A Complete Introduction to the Preparation of all the 
 Colours and Fluxes used for Painting on Porcelain, Enamel, Faience 
 and Stoneware, the Coloured Pastes and Coloured Glasses, together 
 with a Minute Description of the Firing of Colours and Enamels. On 
 the Basis of Personal Practical Experience of the Condition of the Art 
 up to Date. By FELIX HERMANN, Technical Chemist. With 18 Illus 
 trations. Second, greatly Enlarged, Edition. Price 10s. fid. : Ger- 
 many, 12 mks. ; France and Belgium. 13 frs., post free. 
 
 Contents. 
 
 History of Glass Painting. Chapters I., The Articles to be Painted: Glass, Porcelain, 
 Enamel, Stoneware, Faience. II., Pigments : i, Metallic Pigments: Antimony Oxide, Naples 
 Yellow, Barium Chromate, Lead Chromate, Silver Chloride, Chromic Oxide. III., Fluxes: 
 Fluxes, Felspar, Quartz, Purifying Quartz, Sedimentation, Quenching, Borax, Boracic Acid, 
 Potassium and Sodium Carbonates, Rocaille Flux. IV., Preparation of the Colours for Glass 
 Painting. V 7 ., The Colour Pastes. VI., The Coloured Glasses. VII., Composition of the 
 Porcelain Colours. VIII., The Enamel Colours: Enamels for Artistic Work. IX., Metallic 
 Ornamentation: Porcelain Gilding, Glass Gilding. X., Firing the Colours: i, Remarks on 
 Firing: Firing Colours on Glass, Firing Colours on Porcelain; 2, The Muffle XL, Accidents 
 occasionally Supervening during the Process of Firing. XII., Remarks on the Different 
 Methods of Painting on Glass, Porcelain, etc. Appendix : Cleaning Old Glass Paintings. 
 
 Press Opinions. 
 
 " A reliable treatise on the preparation of the colours and fluxes, with exhaustive quantitative 
 recipes, and minute descriptions of the firing of colours and enamels, is of no small technical 
 importance, and emanating from so distinguished an authority as Felix Hermann, Brongniart's 
 successor in the direction of the Sevres manufactory, merits the earnest study of all engaged in 
 the porcelain and kindred industries in England. ... In every district of England where art 
 porcelain and glass is manufactured this treatise should be widely circulated, and its contents 
 made familiar to all engaged, in whatever capacity, in the trade." Leeds Mercury. . 
 
 " The whole cannot fail to be both of interest and service to glass workers and to potters 
 'generally, especially those employed upon high-class work." Staffordshire Sentinel. 
 
10 
 
 A Reissue of THE HISTORY OF THE STAFFORDSHIRE 
 POTTERIES; AND THE RISE AND PROGRESS OF THE 
 MANUFACTURE OF POTTERY AND PORCELAIN. With 
 References to Genuine Specimens, and Notices of Eminent Potters. 
 By SIMEON SHA\V. (Originally Published in 1829.) Price 7s. 6d., 
 strictly net. post free ; Abroad, 9s. 
 
 Contents. 
 
 Introductory Chapter showing the position of the Pottery Trade at the present time 
 (1899). Chapters I.. Preliminary Remarks. II.. The PotteVies. comprising Tunstall. 
 Brownhills, Greenfield and New Field, Golden Hill, Latebrook, Green Lane, Burslem. 
 Longport and Dale Hall, Hot Lane and Cobridge, Hanley and She'ton, Etruria, Stoke, Penk- 
 hull, Fenton, Lane Delph, Foley, Lane End. III., On the Origin of the Art, and its 
 Practice among the early Nations. IV., Manufacture of Pottery, prior to 1700.%".. The 
 Introduction of Red Porcelain by Messrs. Elers, of Bradwell, 1690. VI., Progress of 
 the Manufacture from 1700 to Mr. Wedgewood's commencement in 1760. VII.. lntroduc = 
 tion of Fluid Glaze. Extension of the Manufacture of Cream Colour. Mr. Wedgwood's 
 Queen's Ware. Jasper, and Appointment of Potter to her Majesty. Black Printing. VIII.. 
 Introduction of Porcelain. Mr. W. Littler's Porcelain. Mr, Cookworthy's Discovery of 
 Kaolin and Petuntse, and Patent. Sold to Mr. Champion resold to the New Hall Com. 
 Extension of Term. IX., Blue Printed Pottery Mr. Turner, Mr. Spode (i), Mr. Baddeley, 
 Mr. Spode (2), Messrs. Turner, Mr. Wood, Mr. Wilson, Mr. Minton. Great Change in 
 Patterns of Blue Printed. X., Introduction of Lustre Pottery. Improvements in Pottery 
 and Porcelain subsequent to 1800. 
 
 Press Opinions. 
 
 " This work is all the more valuable because it gives one an idea of the condition of affairs 
 existing in the north of Staffordshire before the great increase in work and population due to 
 modern developments." ]\'fstcrn .Morning News. 
 
 " The book will be especially welcomed at a time when interest in the art of pottery manu- 
 facture commands a more widespread and general interest than at any previous time." ir<>/;'< r- 
 hamptcn Chronicle. 
 
 " Copies of the original work are now of considerable value, and the facsimile reprint now issued 
 cannot but prove of considerable interest to all interested in the great industry." Derby Mercury . 
 " There is much curious and useful information in the work, and the publishers have rendered 
 the public a service in reissuing it." Burton Mail. 
 
 A Reissue of THE CHEMISTRY OF THE SEVERAL 
 NATURAL AND ARTIFICIAL HETEROGENEOUS COM- 
 POUNDS USED IN MANUFACTURING PORCELAIN, 
 GLASS, AND POTTERY. By SIMEON SHAW. (Originally 
 Published in 1837.) Price 17s. 6d. ; Colonies and Continent, 18s:, 
 strictly net, post free. 
 
 Contents. 
 
 PART I., ANALYSIS AND MATERIALS Chapters I , Introduction: Laboratory and 
 Apparatus; Elements: Combinative Potencies, Manipulative Processes for Analysis and 
 Reagents, Pulverisation, Blow-pipe Analysis, Humid Analysis. Preparatory Manipulations, 
 General Analytic Processes, Compounds Soluble in Water, Compounds Soluble only in 
 Acids, Compounds (Mixed) Soluble in Water, Compounds (Mixed) Soluble in Acids, Compounds 
 (Mixed) Insoluble, Particular Analytic Processes II., Temperature : Coal, Steam Heat for 
 Printers' Stoves III., Acids and Alkalies: Boracic Acid, Muriatic Acid, Nitric Acid, Sul- 
 phuric Acid, Potash, Soda. Lithia, Calculation of Chemical Separations IV., The Earths : 
 Alumine, Clays, Silica, Flint. Lime, Plaster of Paris, Magnesia, Barytes, Felspar, Grauen (or 
 China Stone) China Clay, Chert V., Metals : Reciprocal Combinative Potencies of the Metals. 
 Antimony, Arsenic, Chromium, Green Oxide, Cobalt, Chromic Acid, Humid Separation of 
 Nickel from Cobalt, Arsenite of Cobalt, Copper, Gold, Iron, Lead, Manganese, Platinum, Silver. 
 Tin, Zinc. 
 
 PART II., SYNTHESIS AND COMPOUNDS. Chapters I., Sketch of the Origin and 
 Progress of the Art II., Science of Mixing: Scientific Principles of the Manufacture, Com- 
 binative Potencies of the Earths. III., Bodies: Porcelain Hard, Porcelain- Fritted Bodies, 
 Porcelain Raw Bodies. Porcelain Soft, Fritted Bodies, Raw Bodies, Stone Bodies, Ironstone, 
 Dry Bodies, Chemical Utensils, Fritted Jasper, Fritted Pearl, Fritted Drab. Raw Chemical 
 Utensils, Raw Stone, Raw Jasper, Raw Pearl, Raw Mortar, Raw Drab, Raw Brown Raw Fawn, 
 Raw Cane, Raw Red Porous, Raw Egyptian, Earthenware, Queen's Ware, Cream Colour, Blue 
 and Fancy Printed, Dipped and Mocha, Chalky, Rings, Stilts, etc. IV., Glazes: Porcelain- 
 Hard Fritted, Porcelain Soft Fritted, Porcelain Soft Raw, Cream Colour Porcelain, Blue 
 Printed Porcelain, Fritted Glazes, Analysis of Fritt, Analysis of Glaze, Coloured Gla/ces, Dips, 
 Smears, and Washes; Glasses: Flint Glass, Coloured Glasses, Artificial Garnet, Artificial 
 Emerald, Artificial Amethyst, Artificial Sapphire, Artificial Opal, Plate Glass, Crown Glass, 
 Broad Glass, Bottle Glass/Phosphoric Glass, British Steel Glass, Glass-Staining and Painting, 
 Engraving on Glass, Dr. Faraday's Experiments. V., Colours: Colour Making, Fluxes or 
 Solvents, Components of the Colours; Reds, etc., from Gold, Carmine or Rose Colour, 
 Purple, Reds, etc., from Iron, Blues, Yellows, Greens, Blacks, White, Silver for Burnishing. 
 Gold for Burnishing, Printer's Oil, Lustres. 
 
11 
 
 PART III., TABLES OF THE CHARACTERISTICS OF CHEMICAL SUB- 
 STANCES. Preliminary Remarks, Oxygen (Tables), Sulphur and its Compounds, Nitrogen 
 ditto, Chlorine ditto, Bromine ditto, Iodine ditt?. Fluorine ditto, Phosphorus ditto, Boron ditto, 
 Carbon ditto. Hydrogen ditto, Observations, Ammonium and its Compounds (Tables), Thorium 
 ditto, Zirconium ditto, Aluminium ditto, Yttrium ditto, Glucinum ditto, Magnesium ditto, 
 Calcium ditto, Strontium ditto, Barium ditto. Lithium ditto, Scdium and its Compounds, 
 Potassium ditto, Observations, Selenium and its Compounds (Tables), Arstnic ditto, Chromium 
 ditto, Vanadium ditto, Molybdenum ditto, Tungsten ditto, Antimony ditto, Tellurium ditto, 
 Tantalum ditto, Titanium ditto, Silicium ditto, Osmium ditto, Go'd ditto, Iridium ditto, Rhodium 
 ditto, Platinum ditto. Palladium ditto, Mercury ditto, Silver ditto, Copper ditto, Uranium ditto, 
 Bismuth aud its Compounds, Tin ditto. Lead ditto, Cerium ditto, Cobalt ditto, Nickel ditto, 
 Iron ditto, Cadmium ditto, Zinc ditto, Manganese ditto, Obse rations, Isomorphous Groups, 
 Isomeric ditto, Metameric ditto, Polymeric ditto, Index. 
 
 ENAMELS AND ENAMELLING. An Introduction to the 
 Preparation and Application of all Kinds of Enamels for Technical 
 and Artistic Purposes. For Enamel Makers, Workers in Gold and 
 Silver, and Manufacturers of Objects of Art. By PAUL RANDAU. 
 Translated from the German. With 16 Illustrations. Price 10s. 6d. ; 
 Abroad, 12s., strictly net, post free. 
 
 Contents. 
 
 I., Introduction. II., Composition and Properties of Glass. III., Raw Materials for the 
 Manufacture of Enamels. IV., Substances Added to Produce Opacity. V., Fluxes. VI., Pig- 
 ments. VII., Decolorising Agents. VIII., Testing the Raw Materials with the Blow-pipe 
 Flame. IX., Subsidiary Materials. X., Preparing the Materials for Enamel Making. XL, 
 Mixing the Materials. XII., The Preparation of Technical Enamels: The Enamel Mass. 
 XIII., Appliances for Smelting the Enamel Mass. XIV., Smelting the Charge. XV., Com- 
 position of Enamel Masses. XVI., Composition of Masses for Ground Enamels. XVII., 
 Composition of Cover Enamels. XVIII., Preparing the Articles for Enamelling. XIX., 
 Applying the Enamel. XX., Firing the Ground Enamel. XXI., Applying and Firing the 
 Cover Enamel or Glaze. XXII., Repairing Defects in Enamelled Ware. XXIII.. Enamelling 
 Articles of Sheet Metal. XXIV., Decorating Enamelled Ware. XXV., Specialities in 
 Enamelling. XXVI., Dial-plate Enamelling XXVII., Enamels for Artistic Purposes: Re- 
 cipes for Enamels of Various Colours. Index. 
 
 Books on Textile Subjects. 
 
 THE TECHNICAL TESTING OF YARNS AND TEXTILE 
 FABRICS, with Reference to Official Specifications. Translated 
 from the German of Dr. J. HERZFELD. With 69 Illustrations. Price 
 10s. 6d. ; France and Belgium, 13 frs. ; Colonies, 12s., post free. 
 
 Contents. 
 
 Yarn Testing. III., Determining: the Yarn Number. IV., Testing the Length 
 of Yarns. V., Examination of the fcxternal Appearance of Yarn. VI.. Determining 
 the Twist of Yarn and Twist. VII., Determination of Tensile Strength and 
 Elasticity. VI 1 1., Estimating the Percentage of Fat in Yarn. IX., Determination 
 of Moisture (Conditioning). Appendix. 
 
 Press Opinions. 
 
 " The author has endeavoured to collect and arrange in systematic form for the first timt all 
 the data relating to both physical and chemical tests as used throughout the whole of the 
 textile industry, so that not only the commercial and textile chemist who has frequently to 
 reply to questions on these matters, but also the practical manufacturer of textiles and his 
 subordinates, whether in spinning, weaving, dyeing, and finishing, are catered for. . . . The 
 book is profusely illustrated, and the subjects of these illustrations are clearly described." 
 Textile Manufacturer. 
 
 " This is probably the most exhaustive book published in English on the subject dealt with. 
 
 . We have great confidence in recommending the purchase of this book by all manufacturers 
 of textile goods of whatever kind, and are convinced that the concise and direct way in which it 
 is written, which has been admirably conserved by the translator, renders it peculiarly adapted 
 for the- use of English readers." Textile Recorder. 
 
 " A careful study of this book enables one to say with certainty that it is a standard work on 
 the subject. Its importance is enhanced greatly by the probability that we have here, for the 
 first time in our own language, in one volume, a full, accurate, and detailed account, by a prac- 
 tical expert, of the best technical methods for the testing of textile materials, whether in the 
 raw state or in the more or less finished product." Glasgow Herald. 
 
 " It would be well if our English manufacturers would avail themselves of this important 
 addition to the extensive list of German publications which, by the spread of technical infor- 
 mation, contribute in no small degree to the success, and sometimes to the supremacy, of 
 Germany in almost every branch of textile manufacture. " Manchester Courier. 
 
12 
 DECORATIVE AND FANCY TEXTILE FABRICS. With 
 
 Designs and Illustrations. By R. T. LORD. A Valuable Book for 
 Manufacturers and Designers of Carpets, Damask, Dress and all 
 Textile Fabrics. Price 7s. (3d. ; Other Countries, 9s., post free. 
 
 Contents. 
 
 Chapters I., A few Hints on Designing Ornamental Textile Fabrics. II., A few Hints on 
 Designing Ornamental Textile Fabrics (continued). III., A few Hints on Designing Orna- 
 mental Textile Fabrics (continued). IV., A few Hints on Designing Ornamental Textile 
 Fabrics (continued). V., Hints for Ruled-paper Draughtsmen. VI., The Jacquard Machine. 
 VII., Brussels and Wilton Carpets. VIII., Tapestry Carpets. IX., Ingrain Carpets. X. 
 Axminster Carpets. XI., Damask and Tapestry Fabrics. XII., Scarf Silks and Ribbons 
 XIII., Silk Handkerchiefs. XIV., Dress Fabrics. XV.. Mantle Cloths. XVI., Figured Plush 
 XVII., Bed Quilts. XVIII. Calico Printing. 
 
 Press Opinions. 
 
 "The book is to be commanded as a model manual, appearing at an opportune time, since 
 every day is making known a growing desire for development in British industrial art." 
 Dundee Advertiser. 
 
 " Those engaged in the designing of dress, mantle tapestry, carpet and other ornamental 
 textiles will find this volume a useful work of re'erence." Lceits Mercury. 
 
 " The writer's avocation is that of a designer for the trade, and he therefore knows what he 
 is writing about. . . . The work is well printed and abundantly illustrated, and for the author's 
 share of the work we have nothing but commendation. It is a work which the student designer 
 -will find thoroughly useful." Textile Mercury. 
 
 " Designers especially, who desire to make progress in their calling, will do well to take the 
 hints thrown out in the first four chapters on 'Designing Ornamental Textile Fabrics 1 .' 
 Nottingham Daily Guardian. 
 
 " The book can be strongly recommended to students and practical men." Textile CoLmst. 
 
 POWER-LOOM WEAVING AND YARN NUMBERING, 
 
 according to various Systems, with Conversion Tables. An Auxiliary 
 and Text-book for Pupils of Weaving Schools, as well as for self- 
 instruction and for general use, by those engaged in the Weaving 
 Industry. Translated from the German of ANTHON GRUNER. With 
 Coloured Diagrams. Price 7s. 6d. ; Abroad, 9s., strictly net, post 
 
 free. 
 
 Contents. 
 
 I., Power- Loom Weaving in General. Various Systems of Looms. II , Mounting 
 and Starting the Power=Loom. English Looms. Tappet or Treadle Looms. Dobbies. 
 III., General Remarks on the Numbering, Reeling and Packing of Yarn. Appendix. 
 Useful Hints. Calculating Warps. We.t Calculations. Calculations of Cost Price in Hanks. 
 
 Press Opinions. 
 
 " This work brings before weavers who are actually engaged in the various branches of 
 fabrics, as well as the technical student, the different parts of the general run of power-looms in 
 such a manner that the parts of the loom and their bearing to each other can be readily under- 
 stood. . . . The work should prove of much value, as it is in every sense practical, and is put 
 before the reader in such a clear manner that it can be easily understood." Textile Industrie*. 
 
 " The work has been clearly translated from the German and published with suitable 
 illustrations. . . . The author has dealt very practically with the subject." HradforJ Daily 
 Telegraph. 
 
 " The book, which contains a number of useful coloured diagrams, should prove invaluable 
 to the student, and its handy form will enable it to become a companion more than some cum- 
 brous work." Cotton 1-actory Times. 
 
 " The book has been prepared with great care, and is most usefully illustrated. It is a capital 
 text-book for use in the weaving schools or for self-instruction, while all engaged in the weaving 
 industry will find its suggestions helpful." Xottheni Daily Telegraph. 
 
 THE COLOUR PRINTING OF CARPET YARNS. A Useful 
 
 Manual for Colour-Chemists and Textile Printers, by DAVID PATKRSON, 
 F.C.S. 132pp. Illustrated. Price 7s. 6d. ; Abroad, 9s.. strictly net, 
 p >st free. 
 
13 
 
 Contents. 
 
 Chapters I., Structure and Constitution of Wool Fibre. II., Yarn Scouring. III., Scouring 
 Materials. IV., Water for Scouring. V., Bleaching Carpet Yarns. VI., Colour Making for 
 Yarn Printing. VII., Colour Printing Pastes. VIII., Cplour Recipes for Yarn Printing. 
 IX., Science of Colour Mixing. X., Matching of Colours. XL, "Hank" Printing. XII., 
 Printing Tapestry Carpet Yarns. XIII., Yarn Printing. XIV., Steaming Printed Yarns. 
 XV., Washing of Steamed Yarns. XVI., Aniline Colours suitable for Yarn Printing. 
 XVII., Glossary of Dyes and Dye-wares used in Wood Yarn Printing. Appendix. 
 Press Opinions. 
 
 " The subject is very exhaustively treated in all its branches. . . . The work, which is very 
 well illustrated with designs, machines, and wool fibres, will be a useful addition to our textile 
 literature." Northern Whig. 
 
 " The book is worthy the attention of the trade." Worcester Herald. 
 
 " An eminent expert himself, the author has evidently strained every effort in order to make 
 his work the standard guide of its class" Leicester Post. 
 
 " It gives an account of its subject which is both valuable and instructive in itself, and likely 
 to be all the more welcome because books dealing with textile fabrics usually have little or 
 nothing to say about this way of decorating them." Scotsman. 
 
 " The work shows a thorough grasp of the leading characteristics as well as the minutiae of 
 the industry, and gives a lucid description of its chief departments. ... As a text-book in 
 technical schools where this branch of industrial education is taught the book is valuable, 
 or it may be perused with pleasure as well as profit by any one having an interest in textile 
 industries." Dundee Courier. 
 
 " The treatise is arranged with great care, and follows the processes described in a manner 
 at once clear and convincing." Glasgow Record. 
 
 " The book bears every mark of an extensive practical knowledge of the subject in all its 
 bearings, and supplies a real want in technical literature. Chapters IX. and X., on the science 
 of colour mixing and colour matching respectively, are especially good, and we do not remember 
 to have seen the bearing of various kinds of light, and of the changes from one kind of light to 
 another on the work of the colourist, so well treated elsewhere." Dyer and Calico Printer. 
 
 " It is thoroughly practical, and contains much information which has not hitherto appeared 
 in book form. It is pleasing to note that the practical part is not crowded out with purely 
 ' practical recipes '. A few typical examples are given, and the rest is left to the common sense 
 and judgment of the printer or works' chemist. Another pleasing feature is the accounts given 
 here and there of the author's own researches on the subject. The work will be of interest to 
 printers of wool generally, and to those engaged in the dyeing of this fibre. "Journal of the 
 Society of Dyers and Cokntrists. 
 
 THE SCIENCE OF COLOUR MIXING. A Manual in- 
 tended for the use of Dyers, Calico Printers and Colour Chemists. 
 By DAVID PATERSON, F.C.S. Forty-one Illustrations, five Coloured 
 Plates, and four Plates showing eleven Dyed Specimens of Fabrics. 
 Price 7s. fid. ; Abroad, 9s., strictly net, post free. 
 
 Contents. 
 
 Chapters I., Colour a Sensation; Colours of Illuminated Bodies; Colours of Opaque and 
 Transparent Bodies; Surface Colour. II., Analysis of Light; Spectrum; Homogeneous 
 Colours; Ready Method of Obtaining a Spectrum. III., Examination of Solar Spectrum : 
 The Spectroscope and its Construction; Colourists' Use of the Spectroscope. IV., Colour by 
 Absorption; Solutions and Dyed Fabrics; Dichroic Coloured Fabrics in Gaslight. V., Colour 
 Primaries of the Scientist versus the Dyer and Artist ; Colour Mixing by Rotation and Lye 
 Dyeing; Hue, Purity, Brightness; Tints; Shades, Scales, Tones, Sad and Sombre Colours. 
 VI., Colour Mixing; Pure and Impure Greens, Orange and Violets; Large Variety of Shades 
 from Few Colours; Consideration of the Practical Primaries: Red, Yellow and Blue. VII., 
 Secondary Colours ; Nomenclature of Violet and Purple Group: Tints and Shades of Violet ; 
 Changes in Artificial Light. VIII., Tertiary Shades; Broken Hues; Absorption Spectra of 
 Tertiary Shades. Appendix : Four Plates with Dyed Specimens illustrating Text. Index. 
 
 Books on Plumbing. 
 
 EXTERNAL PLUMBING WORK. A Treatise on Lead Work 
 for Roofs. By JOHN W. HART, R.P.C. Price 7s. 6d., post free; Other 
 Countries, 8s. 
 
 List of Chapters. 
 
 Chapters I., Cast Sheet Lead. II., Milled Sheet Lead. III., Roof Cesspools. IV., Socket 
 Pipes. V., Drips. VI., Gutters. VII., Gutters (continued). VIII., Breaks. IX., Circular 
 Breaks. X., Flats. XL, Flats (continued). Xll., Rolls on Flats. XIII., Roll Ends. XIV., 
 Roll Intersections. XV., Seam Rolls. XVI., Seam Rolls (continued). XVIL, Tack Fixings. 
 XVIII. , Step Flashings. XIX., Step Flashings (continued). XX., Secret Gutters. XXI... 
 
14 
 
 Soakers. XXII.. Hip and Valley Soakers. XXIII., Dormer Windows. XXIV.. Dormer 
 Windows (continued). XXV., Dormer Tops. XXVI., Internal Dormers. XXVII., Skylights. 
 -XXVIII., Hips and Ridging.-XXIX., Hips and Ridging (continued).-XXX.. Fixings for 
 Hips and Ridging. XXXI. .Ornamental Ridging. XXXI 1., Ornamental Curb Rolls. XXXIII., 
 Curb Rolls. XXXIV., Cornices. XXXV., Towers and Finials. XXXVI., Towers and Finials 
 (continued). XXXVII., Towers and Finials (continued). XXXVIII.. Domes. XXXIX. .Domes 
 (continued). XL., Ornamental Lead Work. XLL, Rain Water Heads. XLII., Rain Water 
 Heads (continued). XLIII., Rain Water Heads (continued) 
 
 Press Opinions. 
 
 "The publication of this book will do much to stimulate attention and study to external 
 plumbing work, for it is a book which we can heartily recommend to every plumber, both old 
 and young, who desires to make himself proficient in the several branches of his trade. We 
 can heartily recommend the book to plumbers and architects." Sanitary Record. 
 
 " This is an eminently practical and well-illustrated volume on the management of external 
 lead work." Birmingham Daily Post. 
 
 " It is thoroughly practical, containing many valuable hints, and cannot fail to be of great 
 benefit to those who have not had large experience." Sanitary Journal. 
 
 " With Mr. Hart's treatise in his hands the young plumber need not be afraid of tackling 
 outside work. He would do well to study its pages at leisure, so that he may be ready for it 
 when called upon." Ironmongery. 
 
 " Works on sanitary plumbing are by no means rare, but treatises dealing with external 
 plumbing work are sufficiently scarce to ensure for Mr. Hart's new publication a hearty recep- 
 tion." Tilt Ironmonger. 
 
 HINTS TO PLUMBERS ON JOINT WIPING, PIPE 
 BENDING AND LEAD BURNING. Second Edition, Revised 
 and Corrected. By JOHN W. HART, R.P.C. Over 300 pages, Illus- 
 trated. Price 7s. 6d. ; Other Countries, 8s., post free. 
 
 List of Chapters. 
 
 x., Introduction. Chapters I., Pipe Bending. II., Pipe Bending (continued). III., Pipe 
 Bending (continued). IV., Square Pipe Bendings. V., Half-circular Elbows. VI., Curved 
 Bends on Square Pipe. VII., Bossed Bends. VIII., Curved Plinth Bends. IX., Rain-water 
 Shoes on Square Pipe. X., Curved and Angle Bends. XL, Square Pipe Fixings. XII., Joint- 
 wiping. XIII., Substitutes for Wiped Joints. XIV., Preparing Wiped Joints. XV., Joint 
 Fixings. XVI., Plumbing Irons. XVII., Joint Fixings. XVIII. , Use of " Touch" in Solder- 
 ing. XIX., Underhand Joints. XX., Blown and Copper Bit Joints. XXL, Branch Joints. 
 XXIL, Branch Joints (continued). XXIII. , Block Joints. XXIV., Block Joints (continued). 
 XXV.. Block Fixings. XXVI. , Astragal Joints Pipe Fixings. XXVII. , Large Branch 
 Joints. XXVIIL, Large Underhand Joints. XXIX., Solders. XXX., Autogenous Soldering 
 or Lead Burning. 
 
 Press Opinions. 
 
 " Rich in useful diagrams as well as in hints." Liverpool Mcrcitiy. 
 
 " A *vell got-up and well-done practical book. It is freely illustrated and is a reliable help in 
 respect of some of the most awkward work the young plumber has to perform." The Ironmonger. 
 
 " The papers are eminently practical, and go much further into the mysteries they describe 
 than the title ' Hints' properly suggests." Scotsman. 
 
 "The articles are apparently written by a thoroughly practical man. As a practical guide 
 the book will doubtless be of much service." Glasgow Herald. 
 
 " So far as the practical hints in this work are concerned, it will bi useful to apprentices and 
 students in technical schools, as it deals mainly with the most important or difficult branches of 
 the plumber's craft, viz., joint wiping, pipe bending and lead burning. . . . ' Hints ' are the 
 most useful things to an apprentice, and there are many in this work which are not to be found 
 in some of the text-books." English Mechanic. 
 
 " It is a book for the intelligent operative first of all, not a mere manual of instruction 
 for the beginner, nor yet a scientific treatise on the whole art of sanitary plumbing. The 
 special subject with which it deals is joint-making, the most important branch of the operative's 
 work, and into this topic the author goes with a thoroughness that is full of suggestion to even 
 the most experienced workman. There is no one who has to do with plumbing but could read 
 the book with profit." Ironmongery. 
 
15 
 WORKS IN PREPARATION 
 
 A HISTORY OF DECORATIVE ART. For Designers, 
 
 Decorators and Workmen. [Nearly Ready. 
 
 HOUSE PAINTING AND DECORATING. A Handbook for 
 Painters and Decorators. [Nearly Ready. 
 
 THE PRINCIPLES AND PRACTICE OF DIPPING, BUR- 
 NISHING AND BRONZING BRASS WORK. [Nearly Ready. 
 
 WAXES. 
 
 AGRICULTURAL CHEMISTRY. 
 
 THE MANUFACTURE OF BRUSHES OF EVERY DES- 
 CRIPTION. 
 
 THE ART AND PRACTICE OF BLEACHING. 
 
 [In the Press. 
 
 THE MANUFACTURE OF LEATHER. Translated from the 
 French of M. VILLON. [In the Press. 
 
 A TREATISE ON THE CERAMIC INDUSTRY. By 
 
 EMILLE BOURRY. 
 
 MINING SAFETY APPLIANCES. 
 
 THE MANUFACTURE OF LAKE PIGMENTS. By T. H. 
 
 JENNISON, F.C.S., etc. [In the Press. 
 
 THE RISKS AND DANGERS OF VARIOUS OCCUPA- 
 TIONS AND THEIR PREVENTIONS. By Dr. L. A. PARRY. 
 
 COLOUR MATCHING ON TEXTILES. A Manual intended 
 for the use of Students of Colour Chemistry, Dyeing and Textile 
 Printing. By DAVID PATERSON, F.C.S. 
 
 TERRA-COTTA, BRICKS AND POTTERY FOR BUILDING 
 PURPOSES. 
 
16 
 TECHNOLOGY OF PETROLEUM. By NHLBLHGHK and 
 
 NOALHAT. 
 
 HOT WATER SUPPLY. ;/ the Press. 
 
 THE CULTURE OF HOPS. [/ the Press. 
 
 THE RONTJEN RAYS IN MEDICAL PRACTICE. 
 CONTINENTAL PATENTS FOR GAS APPARATUS. 
 
 SULPHATES OF IRON AND ALUMINIUM AND ALUM 
 INDUSTRY. By L. GESCHWIND. 
 
 RESINS AND BALSAMS. 
 
 SCOTT, GREENWOOD & CO. 
 
 are Publishers of the following old-established and well-known 
 Trade Journals : 
 
 THE OIL AND COLOURMAN'S JOURNAL. The Organ 
 of the Oil, Paint, Drysaltery and Chemical Trades. Home Subscrip- 
 tion, 7s. 6d. per year; United States, $2; Other Countries. 10s. pet- 
 year. 
 
 THE POTTERY GAZETTE. For the China and Glass Trades. 
 Home Subscription, 7s. fid. per year: United States, #2; Other Coun- 
 tries, 10s. per year. 
 
 THE HATTERS' GAZETTE. Home Subscription, 6s. 6d. per 
 
 year: United States. .$2; Other Countries, 9s. per year. 
 
 THE DECORATORS' GAZETTE AND PLUMBERS* 
 
 REVIEW. Home Subscription, 6s. fid. per year: United States. *'2 
 Other Countric 
 
 19 Lucigate Hill, London, E.G. 
 
 1900. 
 
THIS BOOK IS DUE ON THE LAST DATE 
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 THIS BOOK ON THE DATE DUE. THE PENALTY 
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